- Email: [email protected]
Methanolic extract of Morinda citrifolia Linn. unripe fruit attenuates methamphetamine-induced conditioned place preferences in mice
Biomedicine & Pharmacotherapy 107 (2018) 368–373
Contents lists available at ScienceDirect
Biomedicine & Pharmacotherapy journal homepage: www.elsevier.com/locate/biopha
Methanolic extract of Morinda citrifolia Linn. unripe fruit attenuates methamphetamine-induced conditioned place preferences in mice
T
⁎
Vijayapandi Pandya,b, , Yew Chang Waia, Nurul Fatin Amira Roslana, Arif Sajata, Abdulla Hamid Abdulla Jallba, Kamini Vijeepallama a b
Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia Department of Pharmacology, Chalapathi Institute of Pharmaceutical Sciences, Chalapathi Nagar, Lam, Guntur, 522034, Andhra Pradesh, India
A R T I C LE I N FO
A B S T R A C T
Keywords: Bupropion Conditioned place preference Methamphetamine dependence Mice Noni fruit
The first objective of the present study was to determine the appropriate dose of methamphetamine (Meth) to induce a successful conditioned place preference (CPP) in mice. The next objective was to examine the effect of a methanolic extract of M. citrifolia unripe fruit (MMC) against Meth-induced CPP in mice. In answering to the first objective, following the preconditioning test, an intraperitoneal injection of a fixed dose of Meth (0.5 or 1 or 2 mg/kg, i.p.) or saline (10 ml/kg, i.p.) was given on alternate days during the 10 days conditioning period followed by a postconditioning test conducted in Meth-free state. The first experiment revealed that 0.5 mg/kg of Meth could be an appropriate fixed low dose to induce CPP in mice. Meanwhile, in other experiments, the effect of MMC and bupropion (BUPR) against the expression, extinction, and reinstatement of Meth (0.5 mg/kg)-induced CPP in mice, respectively, was investigated. In a separate set of studies on each phase, an oral administration of MMC (1, 3 and 5 g/kg, p.o.) or BUPR (20 mg/kg, p.o.) was given 60 min prior to CPP postconditioning testing or extinction testing or reinstatement testing in mice. Extinction trials were conducted in Meth-free state to weaken CPP over the next 5 days. Reinstatement test was conducted by a single low dose priming injection of Meth (0.1 mg/kg, i.p.). The present study, however, failed to establish a successful extinction and reinstatement of Meth-CPP in mice. Further studies using other doses of Meth are warranted for a successful establishment of all phases of Meth CPP in mice. This study also demonstrates that MMC (3 and 5 g/ kg, p.o.) and BUPR (20 mg/kg, p.o.) could attenuate the expression of Meth-induced CPP in mice.
1. Introduction Compulsive drug use of methamphetamine (Meth), a psychostimulant with high dependence liability resembling those of heroin and nicotine, currently poses a significant detrimental health issue, globally [1]. Meth is widely abused in many countries, including Malaysia, causing major medical, psychiatric and legal consequences [2]. The effects of Meth abuse on an individual are quite serious and grave. Initially, Meth increases alertness, physical activity, and respiration and reduces fatigue and body weight. However, in long term abuse, it can cause psychosis, violent behaviour, mood disturbance, memory loss and brain dysfunctions [3]. Chronic use of Meth is neurotoxic to dopaminergic and serotonergic neurons in the central nervous system. There are chemical and molecular changes in the brain associated with changes in the activity of dopaminergic system involved in reduced motor skills and impaired learning [3], and increased likelihood
development of Parkinson’s disease [4]. Despite the dangerous documentation of Meth use, there is a report which revealed that the hospital emergency room visits associated with Meth use increased from about 68,000 in 2007 to 103,000 in 2011 in United States [5]. Other than that, a report from National Anti-Drug Agency (AADK) revealed a drastic increase in the use of Meth from 4026 in 2011 to 8133 in 2015 in Malaysia [6]. Nevertheless, currently there is no medication approved by the Food and Drug Administration (FDA) for treating Meth dependence. Globally, many research attempts have been made on pharmacotherapy to alleviate craving to Meth and the probability of relapse [7]. Relapse, or return to drug use following a period of drug cessation by months or years, was preceded by drug craving associated with an intense urge or desire to use the drug, commonly caused by drug re-exposure and/or the environmental cue stimuli that has been formerly brought with the recent drug use [8]. Morinda citrifolia Linn, commonly known as Noni, is a small tree or
⁎ Corresponding author at: Department of Pharmacology, Chalapathi Institute of Pharmaceutical Sciences, Chalapathi Nagar, Lam, Guntur, 522034, Andhra Pradesh, India. E-mail address: [email protected] (V. Pandy).
https://doi.org/10.1016/j.biopha.2018.08.008 Received 22 March 2018; Received in revised form 20 July 2018; Accepted 3 August 2018 0753-3322/ © 2018 Elsevier Masson SAS. All rights reserved.
Biomedicine & Pharmacotherapy 107 (2018) 368–373
V. Pandy et al.
2.4. CPP apparatus
bush, with the height of 2–6 m tall with numerous wide elliptical leaves [9]. It has gained a wide attention globally due to its multifaceted therapeutic benefits. The different parts of Noni such as roots, stems, leaves, barks, flowers and fruits are used to treat cancer, cardiovascular illness (heart disease, hypertension and atherosclerosis), mental illness (depression, anxiety and psychosis), muscle aches, diabetes, sprains, gastric ulcers, poor digestion, menstrual difficulties, sprains and drug addiction [10]. In recent years, the consumption of Noni fruit juice has gradually increased globally, especially, in the South Pacific Island to treat a wide range of diseases [11]. In a recent report, MMC has been shown to attenuate ethanol CPP in mice [12] and heroin CPP in rats [13] and suggested of its therapeutic potential against alcohol and heroin dependence. In continuation to these recent reports, the present study has made a first attempt in investigating the mitigating effect of MMC against Meth dependence using a mouse model of CPP. Several drugs such as BUPR are known as appealing medication for the treatment of methamphetamine dependence. In various clinical and preclinical studies, BUPR has been reported for its therapeutic effect against methamphetamine dependence [14–16]. BUPR is used in this study as a reference drug to compare the efficacy of the candidature drug. CPP paradigm is considered as a well-established and reliable animal model to study the rewarding effect of different drugs of abuse, including Meth [17]. CPP protocol primarily consists of three phases (i) acquisition/expression (ii) extinction and (iii) reinstatement. These three phases of CPP mimic the clinical situation of craving, abstinence, and relapse, respectively [18]. The aim of the present study was to determine the appropriate dose of Meth to induce conditioned place preference (CPP) in mice in our laboratory and to examine the effect of MMC and BUPR against the expression, extinction and reinstatement of Meth-induced CPP in mice.
CPP apparatus used for this study was a plexiglass box with the following specifications: 45(L) × 15(W) × 15(H) cm. With an insertion of two detachable plexiglass partitions, a small middle gray compartment measuring 5 × 15 × 15 cm is used to separate the CPP apparatus into two equal sized outer compartments (20 × 15 × 15 cm). The equal sized compartments were black and white compartment with different visual and tactile cues. The white compartment had white walls with black vertical stripes with a white wire mesh base while the black compartment had black walls with white horizontal stripes with a black smooth plexiglass base. To close off both white and black compartments, matched detachable plexiglass partitions were used. The plexiglass lid was designed to be transparent to monitor the animals’ behaviour on a computer linked to a Logitech HD webcam set over the CPP box. The animals’ behaviour was then displayed on the computer and later scored by an observer who was blind to the treatment protocol. The CPP methodology was separated into three different phases: acquisition/expression, extinction and reinstatement. The experiments were performed in a quiet experimental room and carried out during the same session of each day (0800–1600) for the purpose of increasing accuracy of experimental results.
2.5. Determination of an appropriate dose of Meth to induce CPP in mice 2.5.1. Habituation, and preconditioning The mice were subjected to 3 days of habituation and 1 day of preconditioning in the CPP test box. During the habituation period, each mouse was confined in the centre gray compartment for 5 min, both detachable partitions were then removed to allow the mice to freely access both compartments for 15 min. On the preconditioning day, animals were subjected in the same manner similar to habituation, with the time being spent in each compartment noted. The conditioning score was calculated by subtracting time spent by the animals in the white compartment from time spent by the animals in the black compartment and this served as a preconditioning baseline as described previously [13]. In this study, the white compartment was paired with Meth, while the black compartment was paired with saline.
2. Material and methods 2.1. Preparation and phytochemical characterization of MMC MMC was prepared by cold extraction with sonication techniques, as referred to our previous report [19]. The phytochemical profiling details of MMC were reported in our recent article [20]. 2.2. Drugs and chemicals
2.5.2. Conditioning After preconditioning, the mice were subjected to 10 days of conditioning with Meth or saline in the CPP box. During each day of conditioning, Meth group (n = 7–8 per group) received an intraperitoneal injection of Meth (0.5 or 1.0 or 2.0 mg/kg bw, i.p.) and saline (10 ml/kg bw, i.p.) on alternate days (Meth on odd days and saline on even days) in white and black compartment, respectively, and confined for 30 min in the respective compartment whereas the saline control group received saline in both compartments on both days. After 30 min of conditioning, the mice were sent to their home cages.
Methamphetamine hydrochloride (Sigma-Aldrich, St.Louis, MO, USA) was dissolved in sterile normal saline and it was administered intraperitoneally in the fixed volume of 10 ml/kg body weight of mice. MMC and bupropion (LKT Laboratories, St. Paul MN) were suspended in 1%w/v of sodium carboxymethyl cellulose (CMC) solution and were administered orally (p.o). CMC per se treated group served as a vehicle control. 2.3. Animals Male ICR mice of 7–8 weeks age, weighing 25–30 g, obtained from University Kebangsaan Malaysia (UKM) were housed in polycarbonate cages (4–5 animals per cage) enriched by introducing shredded paper at controlled temperature of 20–22 °C and humidity of 45–60%. The animals were obtained two weeks before use and were maintained at 12-h light: 12-h dark cycle (lights on at 7 AM). During the period of experimentation, animals were given unrestricted access to food pellets and purified drinking water. All animals were properly handled with at least one week before the experiment started. Proper animal care was given to reduce stress on the animals. The experimental protocols were assessed and validated by the Institutional Animal Care and Use Committee, Faculty of Medicine, University of Malaya, Kuala Lumpur (Approval No. 2016-190908/PHAR/R/VP).
2.5.3. Postconditioning One day after the last conditioning (Day 15), the mice were allowed to rest (no experiment was performed). On day 16 (48 h after the last conditioning session), postconditioning test was performed as described for preconditioning test. On this day, the mice were given neither saline nor Meth so they were in drug free state. Each mouse in the Meth-free state was placed in the centre gray compartment for 5 min and allowed freely to access between both compartments for 15 min. The time spent in each compartment was recorded and conditioning score was determined and denoted as postconditioning score.
369
Biomedicine & Pharmacotherapy 107 (2018) 368–373
V. Pandy et al.
2.6. Evaluation of the effect of MMC and bupropion on expression, extinction, and reinstatement of Meth (0.5 mg/kg)-induced CPP, respectively, in mice 2.6.1. Habituation, preconditioning, conditioning and postconditioning The experimental protocol was followed as described in the previous experiment for the appropriate dose determination. 2.6.2. Effect of MMC and BUPR on expression of 0.5 mg/kg Meth-induced CPP To study the effect of vehicle (CMC), BUPR and MMC on the rewarding properties of Meth, a different set of mice (n = 7–8 per group) were administered orally with 20 mg/kg of BUPR or 1, 3, and 5 g/kg of MMC or 10 ml/kg of 1% w/v CMC on post conditioning day (Day 16) respectively, 60 min prior to the CPP testing.
Fig. 1. Effect of Meth (0.5, 1.0 and 2.0 mg/kg, i.p.) on the conditioning score of CPP test in mice. Data are indicated as the mean difference ( ± SEM) between the time spent in the Meth-paired compartment and the time spent in the compartment paired with saline (n = 7–8/group). There was a significant difference (***p < 0.001) when compared between preconditioning and postconditioning scores. When not indicated, the difference was not statistically significant.
2.6.3. Extinction of Meth-induced CPP Extinction tests were carried out for 5 days (day 17–day 21) from next day of postconditioning which consisted of daily 15 min CPP testing as described for postconditioning test and the conditioning scores were determined. Neither Meth nor the saline intraperitoneal injection (i.p.) was given during this extinction session.
2.8. Statistical analysis All data are presented as mean ± SEM. Statistical analysis was done by GraphPad Prism 5 statistical software using a mixed two-factor (Group × Session) repeated measures two-way ANOVA for CPP studies followed by post hoc Bonferroni test (preconditioning versus postconditioning) and one-way ANOVA for locomotor activity followed by a post hoc Dunnett’s multiple comparisons test. The values of p < 0.05 were set as statistically significant.
2.6.4. Effect of MMC and BUPR on extinction of 0.5 mg/kg Meth-induced CPP To study the effect of vehicle (CMC), MMC and BUPR on the extinction of Meth-induced CPP, the animals were distinguished into two groups (saline-treated and Meth-treated) which were subjected to preconditioning, conditioning and postconditioning phase as mentioned above. The CPP-induced Meth animals were further divided into vehicle, BUPR and MMC -treated groups (n = 6–7 per group) which received orally with 20 mg/kg BUPR or 1, 3, and 5 g/kg of MMC or 10 ml/ kg of 1% w/v CMC, respectively, 60 min prior to the CPP testing for 15 min during extinction 1 to extinction 5 (Day 17- Day 21).
3. Results 3.1. Determination of an appropriate dose of Meth to induce CPP in mice The different doses of Meth (0.5, 1 and 2 mg/kg, i.p.) were employed in CPP testing to find an appropriate dose of Meth to induce CPP in mice. The pre- and postconditioning results are presented in Fig. 1. A repeated measures two-way ANOVA results revealed a significant effect of Group [F (3, 26) = 3.593; P = 0.0269], Trial [F (1, 26) = 44.37; P < 0.0001] and Group × Trial interactions [F (3, 26) = 9.214; P = 0.0003]. A post hoc Bonferroni test (compared preconditioning versus postconditioning) revealed that Meth (0.5 and 1 mg/kg, i.p.) significantly (P < 0.001) increased the postconditioning scores when compared with its corresponding preconditioning scores which implies the induction of CPP with the effective doses of Meth (0.5 and 1 mg/kg, i.p.) in mice (Fig. 1). Interestingly, Meth at relatively higher dose 2 mg/ kg did not significantly alter the postconditioning score.
2.6.5. Reinstatement of Meth-induced CPP On day 22, a day after the last extinction trial, the test animals were allowed to rest (no experiment was conducted). On day 23 (48 h after the last extinction session), reinstatement test was performed. 2.6.6. Effect of MMC and BUPR on a low dose Meth-priming reinstatement of CPP To study the effect of MMC, BUPR and vehicle (CMC) on the reinstatement of Meth-induced CPP, the animals were divided into salinetreated and Meth-treated and were subjected to postconditioning and extinction trials for 5 days. Following one-day rest of the last extinction trial (Day 22), the treatment groups (n = 7–8 per group) received an oral gavage of 20 mg/kg BUPR or 1, 3, and 5 g/kg of MMC or 10 ml/kg of 1% w/v CMC respectively, 45 min prior to a priming injection of a low dose of Meth (0.1 mg/kg, i.p.). After 15 min of a priming Meth injection, animals were subjected to 15 min CPP testing as described for postconditioning test and the conditioning score was determined.
3.2. Effect of MMC and BUPR on expression of Meth-induced CPP in mice The effect of MMC and BUPR on expression of Meth-induced CPP in mice is presented in Fig. 2. A repeated measures two-way ANOVA results revealed a significant effect of Trial [F (1, 41) = 22.16; P < 0.0001] whereas Group [F (5, 41) = 1.11; P = 0.3699] and Group × Trial interaction [F (5, 41) = 2.04; P = 0.0928] were found to be insignificant. A post hoc Bonferroni test (compared preconditioning versus postconditioning) revealed that Meth (0.5 mg/kg, i.p.) significantly (p < 0.01) increased the postconditioning score when compared with its corresponding preconditioning score which implies the induction of CPP with a minimum effective dose of Meth (0.5 mg/ kg, i.p.) in mice. Similarly, MMC (1 g/kg)-treated group also showed a significant difference (p < 0.05) between its pre- and postconditioning scores which implies the inability of MMC at 1 g/kg to reduce the postconditioning score. Interestingly, MMC at 3 and 5 g/kg attenuated Meth-induced CPP in mice which is evident from non-significant difference between pre- and postconditioning scores. The reference drug,
2.7. Effect of MMC per se on spontaneous locomotor activity in mice The spontaneous locomotor activity was assessed using actimeter (Model: ACT-01, Orchid’s Scientific, Nasik, India) fabricated with clear square Plexiglas arena (50 cm × 50 cm), equipped with 32-infrared sensors. The mice were divided into four groups (N = 10) and administered with 1% CMC (10 ml/kg, p.o.) and MMC at different doses of 1, 3 and 5 g/kg, p.o., respectively, 60 min prior to the test. The spontaneous locomotor activity was assessed for 10 min in actimeter by placing the mouse in the centre arena. The data are expressed as the total light beam interruptions (locomotor counts) per 10 min. The floor of the apparatus was cleaned with 20% v/v ethanol between tests. 370
Biomedicine & Pharmacotherapy 107 (2018) 368–373
V. Pandy et al.
Fig. 2. Effect of MMC (1, 3 and 5 g/kg, p.o.) and BUPR (20 mg/kg, p.o.) on the expression of Meth-induced CPP in mice. Data are indicated as the mean difference ( ± SEM) between the time spent in the Meth-paired compartment and the time spent in the compartment paired with saline (n = 7–8/group). There was a significant difference (*P < 0.05; **P < 0.01) when compared between preconditioning and postconditioning scores. When not indicated, the difference was not statistically significant.
Fig. 4. Effect of MMC (1, 3 and 5 g/kg, p.o.) and BUPR (20 mg/kg, p.o.) on a low dose Meth (0.1 mg/kg, i.p.)-priming reinstatement of CPP in mice. Data are expressed as the mean difference ( ± SEM) between the time spent in Methcompartment and the time spent in the compartment paired with saline (n = 7–8/group).
BUPR (20 mg/kg) also attenuated Meth-induced CPP in mice (no significant difference between its pre- and postconditioning scores). 3.3. Effect of MMC and BUPR on the extinction of Meth-induced CPP in mice The effect of MMC and BUPR on the extinction of Meth-induced CPP is presented in Fig. 3. A repeated measures two-way ANOVA results revealed a non-significant effect of Group [F (5, 35) = 1.645; P = 0.1740], Trial [F (4, 140) = 0.4614; P = 0.7640], and Group × Trial interaction [F (20, 140) = 0.2513; P = 0.9996]. Meth-control group failed to demonstrate any noticeable preference for the Methpaired compartment during entire extinction trials (EXT 1 to EXT 5). Therefore, an expedite effect of treatment groups (MMC and BUPR) on the extinction of Meth-induced CPP in mice could not be determined.
Fig. 5. Effect of MMC (1, 3 and 5 g/kg, p.o.) per se on the spontaneous locomotor activity in mice. Data are presented as Mean ± SEM (n = 10/group). Statistical differences between vehicle (1%w/v CMC)-treated group with MMCtreated groups were analysed by one-way ANOVA followed by post hoc Dunnett’s test.
3.4. Effect of MMC and BUPR on a low dose Meth priming reinstatement of CPP The effect of MMC and BUPR on a low dose Meth priming-induced CPP is shown in Fig. 4. A repeated measures two-way ANOVA results revealed a non-significant effect of Group [F (5, 37) = 1.342; P = 0.2683], Trial [F (1, 37) = 0.03610; P = 0.8503] and Group × Trial Interaction [F (5, 37) = 2.233; P = 0.0715]. Meth-control group failed to show any significant noticeable preference for the Meth-paired compartment on post-reinstatement when compared with its pre-reinstatement. Therefore, the attenuating effect of treatment groups
(MMC and BUPR) on reinstatement of Meth-induced CPP could not be demonstrated in the present study. 3.5. Effect of MMC per se on spontaneous locomotor activity in mice As shown in Fig.5, MMC at all tested doses (1, 3 and 5 g/kg, p.o.) did not significantly affect the spontaneous locomotor activity in mice [F (3, 36) = 1.806; P = 0.1635]. 4. Discussion The effectiveness of MMC and BUPR on the rewarding properties of Meth was systematically evaluated using a mouse model of CPP test in this study. CPP is a standard and reliable behavioural model to study the rewarding effect of various drugs of abuse, including Meth, that is usually associated with the classical Pavlovian conditioning [13]. It has been well documented that the principles of CPP involve the association of learning and memory. Glutamatergic system has been found as a critical neurochemical determinant in various learning and memory animal models including CPP test [17]. The first experiment investigated the appropriate minimum dose of Meth to induce conditioned place preference in mice. The result of the first experiment demonstrated that Meth at doses (0.5 and 1 mg/kg, i.p.) significantly (P < 0.001) induced CPP in mice (Fig. 1). This result corroborates with an earlier published report in which CPP was
Fig. 3. Effect of MMC (1, 3 and 5 g/kg, p.o.) and BUPR (20 mg/kg, p.o.) on the extinction of Meth CPP in mice. Data are expressed as the mean difference ( ± SEM) between the times spent in the Meth-paired compartment and time spent in compartment paired with saline (n = 6–7/group). 371
Biomedicine & Pharmacotherapy 107 (2018) 368–373
V. Pandy et al.
in the market to treat drug dependence (e.g., alcohol, heroin, and nicotine) are reported for their ability to weaken the expression of druginduced CPPs in mice and rats [13,27,28]. Recently, our research group demonstrated that MMC mitigated the expression of heroin-induced CPP and ethanol-induced CPP in rats and mice respectively [13,12]. In the present study, MMC was found to attenuate the expression of Methinduced CPP in mice. These reports revealed the therapeutic potential of MMC against drug dependence and it could be utilized for novel drug discovery in the treatment of drug dependence. Some drugs may show positive results in CPP test, not by acting on the reward pathway, but by simply impairing the learning and memory. For instance, NMDA receptor antagonists were found to exhibit a false positive result in the CPP test [29]. Interestingly, it has been revealed a nootropic effect of M. citrifolia fruit extract in scopolamine-induced memory impairment in mice [30]. Similarly, the ethyl acetate extract of noni fruit reversed the memory impairment induced by beta amyloid in mice [31]. Therefore, the mitigating effect of MMC against Meth-induced CPP could not be mediated through memory impairment mechanism. Other than that, drugs that impair the movement of animals can affect CPP outcome. Nevertheless, there was no alteration in motor activity of mice when the mice were treated with MMC (1, 3 and 5 g/kg, p.o.) per se as shown in Fig. 5 and this result was corroborated with an earlier report on locomotor activity in which noni fruit extract when treated for 21 days did not alter the spontaneous locomotor activity [30] which implies the effect of MMC on Meth-induced CPP was not mediated through motor alterations in mice. Furthermore, an acute oral toxicity study of MMC revealed that no toxic effects of MMC were discovered up to a dose of 20 g/kg in mice [19]. According to OECD guidelines, the extracts which do not exhibit toxic effects up to 2 g/kg, p.o., should be considered safe. The neuronal or neurochemical mechanism underlying the mitigating effect of MMC on expression of Meth-induced CPP in mice were not focused in this study. However, our research group had established the antidopaminergic effect of MMC using in vivo [19] and ex vivo studies [20]. Therefore, we hypothesize that the mitigating effect of MMC against Meth-induced expression of CPP in mice could originate from its antidopaminergic activity. Generally, noni fruit has been suggested to have multiple therapeutic benefits due to its multiple phytoconstituents, such as scopoletin and rutin that are responsible for its antidopaminergic activity [32,33]. Our research group also had performed the phytochemical analysis of MMC and it has been reported that the main phytoconstituents of MMC were characterized and liberated as scopoletin (18.95 μg/mg) and rutin (1.66 μg/mg) [20]. In addition, a previous study postulated that scopoletin and rutin are important in antidopaminergic activity of noni [34]. Moreover, scopoletin and rutin were reported for its interaction with dopamine D2 and D3 receptors in in silico molecular docking studies [35]. It has been postulated that a selective dopamine D3 receptor antagonist could be used to alleviate drug-induced motivation and reward [35]. Although the present work could not confirm the involvement of the bioactive principles of noni, scopoletin and rutin for its mitigating effect against Meth-induced CPP, it has been postulated that these phytoconstituents could be responsible for the mitigating effect of MMC. However, further preclinical studies using scopoletin and rutin per se are warranted in the novel drug discovery for the treatment of Meth dependence. Currently, no FDA-approved drug is available for treating Meth dependence, however, this study utilized BUPR as a reference drug to attenuate Meth-induced CPP in mice. BUPR is an antidepressant and also an approved FDA drug to treat nicotine dependence. Successful offlabel use of this drug to treat Meth-addicts prompted investigators for further studies. BUPR was reported to attenuate Meth self-administration in rats [16]. BUPR is a monoamine uptake inhibitor and inhibits reuptake of dopamine and norepinephrine [36]. Chronic Meth use destroys dopaminergic neurons and results in low dopaminergic tone. The BUPR blocks presynaptic dopamine transporter (DAT) and therefore
significantly induced at a lower dose of 0.5 mg/kg Meth in mice [21]. Interestingly, Meth at a relatively higher dose (2.0 mg/kg, i.p.) failed to demonstrate CPP in mice (Fig. 1). This indicates that the expression of Meth CPP can be achieved only at doses lower than 2 mg/kg. In line with the present findings, an earlier study report demonstrated an inverted U-shaped dose response curve in Meth-induced CPP in mice and suggested the ineffectiveness of Meth at higher doses to induce CPP [22]. The expression of Meth-induced CPP involves association of the rewarding properties of the drug and the environmental cues correlated with it. In this study, the rewarding properties of Meth associated with the environmental cues (white compartment) and tactile cues (mesh floor) lead to preference of the animals to be in the white compartment during postconditioning session. Though Meth significantly induced CPP at 0.5 and 1.0 mg/kg doses, the minimum effective dose of Meth (i.e., 0.5 mg/kg, i.p.) was chosen for the present study. The second experiment was aimed to investigate the effect of MMC against 0.5 mg/kg Meth-induced CPP at different phases of place conditioning such as expression, extinction and reinstatement, mimicking the actual clinical situation of craving, abstinence and relapse, respectively [12]. The results of the second experiment revealed that intraperitoneal administration of Meth (0.5 mg/kg) significantly (p < 0.01) induced CPP in mice (Fig. 2). Interestingly, MMC (3 and 5 g/kg) and BUPR (20 mg/kg) attenuated the expression of Meth (0.5 mg/kg)-induced CPP in mice which was evident from non-significant differences between respective pre- and post-conditioning scores (Fig. 2). However, the present study failed to achieve a significant gradual weakening of CPP by repeated exposure of animals in Meth-free state in the place conditioning environment (Fig. 3). This study also failed to achieve a significant reinstatement by administration of a priming, low dose of Meth (0.1 mg/kg) in Meth-extinct mice (Fig. 4). Due to the unsuccessful establishment of extinction and reinstatement of Meth-induced CPP in the present study, the effect of MMC and BUPR on these phases of CPP could not be determined. Based on the present study results, it has been postulated that Meth (1 mg/kg, i.p.) could be used to induce a significant Meth-CPP in mice and 1/5th of the conditioning dose (i.e., 0.2 mg/kg, i.p.) could be used for establishing reinstatement in Meth-extinct mice. Further studies in this direction are warranted for successful establishment of all phases (expression, extinction and reinstatement) of Meth-induced CPP in mice. Addiction is characterized as compulsive drug seeking behaviour and often related to the chronic consumption of drugs of abuse such as alcohol, cocaine and Meth [13]. Meth passes through the nerve cell membrane directly and enters the nerve terminals [23]. It binds to the vesicular monoamine transporter (VMAT) of the dopamine vesicles and forces the dopamine out of the vesicle to the cytoplasm. Meth also reverses the direction flow of dopamine transporter, leads to release of the dopamine neurotransmitter from the cytoplasm to the synapse, and causes increased in the binding of dopamine to post-synaptic receptors. Moreover, the reuptake of dopamine neurotransmitter is inhibited by Meth, giving rise to an abundance of dopamine remaining in the synapse for a prolonged period and activating the dopamine receptors [23]. Meth works directly on the brain’s reward mechanism and therefore it is highly addictive. The release of dopamine from ventral tegmental area into the nucleus accumbens promotes a positive reinforcement that stimulates the person to repeat the pleasant experience and lead to Meth dependence [24]. Previously, reports of singlephoton emission computed tomography (SPECT) and positron emission tomography (PET) in Meth-addicted users revealed a decline in the number of D2 receptors within the ventral striatum area that remained after a lengthened period of detoxification [25]. In addition, there has been a previous report regarding the administration of D₂ receptor antagonists able to reduce drug self-administration in rat [26]. Thus, it can be hypothesized that the neuromodulatory effect of drugs on dopaminergic system, possibly benefit in the drug addiction therapy. The drugs (e.g., acamprosate, methadone, and bupropion) available 372
Biomedicine & Pharmacotherapy 107 (2018) 368–373
V. Pandy et al.
prevents Meth from acting with DAT and antagonize the effect of Meth. BUPR is able to elevate the concentration of dopamine in the synaptic cleft and maintains the homeostasis of dopamine concentration [37]. BUPR has also been shown to reduce the dopamine reuptake and neurotoxic effects of Meth in rats [16]. Furthermore, a double-blind and placebo-controlled clinical trial evaluating the efficacy between placebo and BUPR (300 mg/d) showed that BUPR is effective in attenuating the Meth withdrawal syndrome in patients and therefore it reduced the use of Meth [38].
Pharmacol. 7 (2016) 352. [13] M. Narasingam, V. Pandy, Z. Mohamed, Noni (Morinda citrifolia L.) fruit extract attenuates the rewarding effect of heroin in conditioned place preference but not withdrawal in rodents, Exp. Anim. 65 (2) (2016) 157–164. [14] T.F. Newton, J.D. Roache, R. De La Garza 2nd, T. Fong, C.L. Wallace, S.H. Li, A. Elkashef, N. Chiang, R. Kahn, Bupropion reduces methamphetamine-induced subjective effects and cue-induced craving, Neuropsychopharmacology 31 (7) (2006) 1537–1544. [15] C.M. Reichel, J.D. Linkugel, R.A. Bevins, Bupropion differentially impacts acquisition of methamphetamine self-administration and sucrose-maintained behavior, Pharmacol. Biochem. Behav. 89 (3) (2008) 463–472. [16] C.M. Reichel, J.E. Murray, K.M. Grant, R.A. Bevins, Bupropion attenuates methamphetamine self-administration in adult male rats, Drug Alcohol Depend. 100 (1-2) (2009) 54–62. [17] Z. He, Y. Chen, H. Dong, R. Su, Z. Gong, L. Yan, Inhibition of vesicular glutamate transporters contributes to attenuate methamphetamine-induced conditioned place preference in rats, Behav. Brain Res. 267 (2014) 1–5. [18] S.T. Pittenger, Examination of Methamphetamine Reinstatement in Female and Male Rats: A Pre-Clinical Model of Relapse, Pro Quest Dissertations & Theses Global, Retrieved from (2016) http://ezproxy.um.edu.my:2048/login?url=https:// search.proquest.com/docview/182325692?accountid=28930. [19] V. Pandy, M. Narasingam, Z. Mohamed, Antipsychotic-like activity of noni (Morinda citrifolia Linn.) in mice, BMC Complement. Altern. Med. 12 (2012) 186. [20] V. Pandy, M. Narasingam, T. Kunasegaran, D.D. Murugan, Z. Mohamed, Effect of noni (Morinda citrifolia Linn.) fruit and its bioactive principles scopoletin and rutin on rat vas deferens contractility: an ex vivo study, Sci. World J. 2014 (2014) 909586. [21] N. Kitanaka, J. Kitanaka, F.S. Hall, G.R. Uhl, K. Watabe, H. Kubo, H. Takahashi, M. Takemura, Attenuation of methamphetamine-induced conditioned place preference in mice after a drug-free period and facilitation of this effect by exposure to a running wheel, J. Exp. Neurosci. 6 (2012) 11–19. [22] C. Achat-Mendes, S.F. Ali, Y. Itzhak, Differential effects of amphetamines-induced neurotoxicity on appetitive and aversive pavlovian conditioning in mice, Neuropsychopharmacology 30 (6) (2005) 1128–1137. [23] R.B. Rothman, M.H. Baumann, C.M. Dersch, D.V. Romero, K.C. Rice, F.I. Carroll, J.S. Partilla, Amphetamine-type central nervous system stimulants release norepinephrine more potently than they release dopamine and serotonin, Synapse 39 (1) (2001) 32–41. [24] G.F. Koob, F.E. Bloom, Cellular and molecular mechanisms of drug dependence, Science 242 (4879) (1988) 715–724. [25] N.D. Volkow, L. Chang, G.J. Wang, J.S. Fowler, Y.S. Ding, M. Sedler, J. Logan, D. Franceschi, J. Gatley, R. Hitzemann, A. Gifford, C. Wong, N. Pappas, Low level of brain dopamine D2 receptors in methamphetamine abusers: association with metabolism in the orbitofrontal cortex, Am. J. Psychiatry 158 (12) (2001) 2015–2021. [26] W.J. Eiler, H.L. June, Blockade of GABA(A)A receptors within the extended amygdala attenuates D 2 regulation of alcohol-motivated behaviors in the ventral tegmental area of alcohol-preferring (P) rats, Neuropharmacology 52 (8) (2007) 1570–1579. [27] M.I. Damaj, S.D. Grabus, H.A. Navarro, R.E. Vann, J.A. Warner, L.S. King, J.L. Wiley, B.E. Blough, R.J. Lukas, F.I. Carroll, Effects of hydroxymetabolites of bupropion on nicotine dependence behavior in mice, J. Pharmacol. Exp. Ther. 334 (3) (2010) 1087–1095. [28] A.J. Mcgeehan, M.F. Olive, The anti‐relapse compound acamprosate inhibits the development of a conditioned place preference to ethanol and cocaine but not morphine, Br. J. Pharmacol. 138 (1) (2003) 9–12. [29] M.A. Aguilar, C. Manzanedo, B.R. Do Couto, M. Rodríguez-Arias, J. Miñarro, Memantine blocks sensitization to the rewarding effects of morphine, Brain Res. 1288 (2009) 95–104. [30] S.D. Pachauri, P.R. Verma, A.K. Dwivedi, S. Tota, K. Khandelwal, J.K. Saxena, C. Nath, Ameliorative effect of noni fruit extract on streptozotocin-induced memory impairment in mice, Behav. Pharmacol. 24 (4) (2013) 307–319. [31] P. Muralidharan, V.R. Kumar, G. Balamurugan, Protective effect of Morinda citrifolia fruits on β‐amyloid (25–35) induced cognitive dysfunction in mice: an experimental and biochemical study, Phytother. Res. 24 (2) (2010) 252–258. [32] V. Pandy, K. Vijeepallam, Antipsychotic-like activity of scopoletin and rutin against the positive symptoms of schizophrenia in mouse models, Exp. Anim. 66 (4) (2017) 417–423. [33] Y. Chan-Blanco, F. Vaillant, A.M. Perez, M. Reynes, J.-M. Brillouet, P. Brat, The noni fruit (Morinda citrifolia L.): a review of agricultural research, nutritional and therapeutic properties, J. Food Compost. Anal. 19 (6) (2006) 645–654. [34] S. Deng, B. West, A. Palu, B. Zhou, C. Jensen, Noni as an anxiolytic and sedative: a mechanism involving its gamma-aminobutyric acidergic effects, Phytomedicine 14 (7) (2007) 517–522. [35] S. Jeyabalan, K. Subramanian, U.M.R. Cheekala, C. Krishnan, GC–MS analysis and in-silico antipsychotic activity of Morinda citrifolia (Indian noni), J. Appl. Pharm. Sci. 7 (4) (2017) 89–95. [36] L. Karila, A. Weinstein, H.J. Aubin, A. Benyamina, M. Reynaud, S.L. Batki, Pharmacological approaches to methamphetamine dependence: a focused review, Br. J. Clin. Pharmacol. 69 (6) (2010) 578–592. [37] L.D. Simmler, R. Wandeler, M.E. Liechti, Bupropion, methylphenidate, and 3, 4methylenedioxypyrovalerone antagonize methamphetamine-induced efflux of dopamine according to their potencies as dopamine uptake inhibitors: implications for the treatment of methamphetamine dependence, BMC Res. Notes 6 (1) (2013) 220. [38] I.D. Montoya, F. Vocci, Novel medications to treat addictive disorders, Curr. Psychiatry Rep. 10 (5) (2008) 392–398.
5. Conclusion Meth exhibits the expression of CPP at a minimum effective dose of 0.5 mg/kg (i.p.), however, it fails to demonstrate a significant extinction and reinstatement of Meth-induced CPP in mice. This study also demonstrates that MMC (3 and 5 g/kg, p.o.) and BUPR (20 mg/kg, p.o.) mitigated the expression of Meth-induced CPP in mice. This implies that MMC attenuated the rewarding properties of Meth which could be utilized to treat Meth dependence. The results of this study could pave the way for other researchers to discover an effective pharmacotherapy for the treatment of Meth dependence. Further clinical studies using MMC are required to assist these preclinical findings and to treat Meth dependence. Funding This study was supported by the University of Malaya Research grants (BKS051-2017; PG232-2015B and PG023-2014B). The funding sources granted for this work were not involved in study design, in the collection, analysis and interpretation of data, in the writing of the report, and in the decision to submit the article for publication. Conflict of interests The authors declare that they have no competing interests. Acknowledgement The authors thank Prof Nor Azizan Abdullah for proofread of this manuscript. References [1] J.J. Nocon, Substance use disorders, in: D.R. Mattison (Ed.), Clinical Pharmacology During Pregnancy, Academic Press, London, 2013, pp. 217–256. [2] Q.T. Chie, C.L. Tam, G. Bonn, C.P. Wong, H.M. Dang, R. Khairuddin, Drug abuse, relapse, and prevention education in Malaysia: perspective of university students through a mixed methods approach, Front. Psychiatry 6 (2015) 65. [3] S. Yu, L. Zhu, Q. Shen, X. Bai, X. Di, Recent advances in methamphetamine neurotoxicity mechanisms and its molecular pathophysiology, Behav. Neurol. 2015 (2015) 103969. [4] B.M. Kuehn, Meth use linked to risk of parkinson disease, JAMA 306 (8) (2011) 814. [5] M.E. Mattson, Emergency Department Visits Involving Methamphetamine: 2007 to 2011, The CBHSQ Report, Substance Abuse and Mental Health Services Administration (US), Rockville (MD), 2013, pp. 1–7. [6] AADK, MAKLUMAT DADAH 2015., Agensi Antidadah Kebangsaan Kementerian Dalam Negeri (2015). [7] A.T. McLellan, D.C. Lewis, C.P. O’Brien, H.D. Kleber, Drug dependence, a chronic medical illness: implications for treatment, insurance, and outcomes evaluation, JAMA 284 (13) (2000) 1689–1695. [8] P.R. Kufahl, M.F. Olive, Investigating methamphetamine craving using the extinction-reinstatement model in the rat, J. Addict. Res. Ther. 1 (3) (2011) 003. [9] W. McClatchey, From polynesian healers to health food stores: changing perspectives of Morinda citrifolia (Rubiaceae), Integr. Cancer Ther. 1 (2) (2002) 110–120. [10] V. Samoylenko, J. Zhao, D.C. Dunbar, I.A. Khan, J.W. Rushing, I. Muhammad, New constituents from noni (Morinda citrifolia) fruit juice, J. Agric. Food Chem. 54 (17) (2006) 6398–6402. [11] B.J. West, C.J. Jensen, J. Westendorf, L.D. White, A safety review of noni fruit juice, J. Food Sci. 71 (8) (2006) R100–R106. [12] Y. Khan, V. Pandy, Methanolic extract of Morinda citrifolia L. (noni) unripe fruit attenuates ethanol-induced conditioned Place preferences in mice, Front.
373
Contents lists available at ScienceDirect
Biomedicine & Pharmacotherapy journal homepage: www.elsevier.com/locate/biopha
Methanolic extract of Morinda citrifolia Linn. unripe fruit attenuates methamphetamine-induced conditioned place preferences in mice
T
⁎
Vijayapandi Pandya,b, , Yew Chang Waia, Nurul Fatin Amira Roslana, Arif Sajata, Abdulla Hamid Abdulla Jallba, Kamini Vijeepallama a b
Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia Department of Pharmacology, Chalapathi Institute of Pharmaceutical Sciences, Chalapathi Nagar, Lam, Guntur, 522034, Andhra Pradesh, India
A R T I C LE I N FO
A B S T R A C T
Keywords: Bupropion Conditioned place preference Methamphetamine dependence Mice Noni fruit
The first objective of the present study was to determine the appropriate dose of methamphetamine (Meth) to induce a successful conditioned place preference (CPP) in mice. The next objective was to examine the effect of a methanolic extract of M. citrifolia unripe fruit (MMC) against Meth-induced CPP in mice. In answering to the first objective, following the preconditioning test, an intraperitoneal injection of a fixed dose of Meth (0.5 or 1 or 2 mg/kg, i.p.) or saline (10 ml/kg, i.p.) was given on alternate days during the 10 days conditioning period followed by a postconditioning test conducted in Meth-free state. The first experiment revealed that 0.5 mg/kg of Meth could be an appropriate fixed low dose to induce CPP in mice. Meanwhile, in other experiments, the effect of MMC and bupropion (BUPR) against the expression, extinction, and reinstatement of Meth (0.5 mg/kg)-induced CPP in mice, respectively, was investigated. In a separate set of studies on each phase, an oral administration of MMC (1, 3 and 5 g/kg, p.o.) or BUPR (20 mg/kg, p.o.) was given 60 min prior to CPP postconditioning testing or extinction testing or reinstatement testing in mice. Extinction trials were conducted in Meth-free state to weaken CPP over the next 5 days. Reinstatement test was conducted by a single low dose priming injection of Meth (0.1 mg/kg, i.p.). The present study, however, failed to establish a successful extinction and reinstatement of Meth-CPP in mice. Further studies using other doses of Meth are warranted for a successful establishment of all phases of Meth CPP in mice. This study also demonstrates that MMC (3 and 5 g/ kg, p.o.) and BUPR (20 mg/kg, p.o.) could attenuate the expression of Meth-induced CPP in mice.
1. Introduction Compulsive drug use of methamphetamine (Meth), a psychostimulant with high dependence liability resembling those of heroin and nicotine, currently poses a significant detrimental health issue, globally [1]. Meth is widely abused in many countries, including Malaysia, causing major medical, psychiatric and legal consequences [2]. The effects of Meth abuse on an individual are quite serious and grave. Initially, Meth increases alertness, physical activity, and respiration and reduces fatigue and body weight. However, in long term abuse, it can cause psychosis, violent behaviour, mood disturbance, memory loss and brain dysfunctions [3]. Chronic use of Meth is neurotoxic to dopaminergic and serotonergic neurons in the central nervous system. There are chemical and molecular changes in the brain associated with changes in the activity of dopaminergic system involved in reduced motor skills and impaired learning [3], and increased likelihood
development of Parkinson’s disease [4]. Despite the dangerous documentation of Meth use, there is a report which revealed that the hospital emergency room visits associated with Meth use increased from about 68,000 in 2007 to 103,000 in 2011 in United States [5]. Other than that, a report from National Anti-Drug Agency (AADK) revealed a drastic increase in the use of Meth from 4026 in 2011 to 8133 in 2015 in Malaysia [6]. Nevertheless, currently there is no medication approved by the Food and Drug Administration (FDA) for treating Meth dependence. Globally, many research attempts have been made on pharmacotherapy to alleviate craving to Meth and the probability of relapse [7]. Relapse, or return to drug use following a period of drug cessation by months or years, was preceded by drug craving associated with an intense urge or desire to use the drug, commonly caused by drug re-exposure and/or the environmental cue stimuli that has been formerly brought with the recent drug use [8]. Morinda citrifolia Linn, commonly known as Noni, is a small tree or
⁎ Corresponding author at: Department of Pharmacology, Chalapathi Institute of Pharmaceutical Sciences, Chalapathi Nagar, Lam, Guntur, 522034, Andhra Pradesh, India. E-mail address: [email protected] (V. Pandy).
https://doi.org/10.1016/j.biopha.2018.08.008 Received 22 March 2018; Received in revised form 20 July 2018; Accepted 3 August 2018 0753-3322/ © 2018 Elsevier Masson SAS. All rights reserved.
Biomedicine & Pharmacotherapy 107 (2018) 368–373
V. Pandy et al.
2.4. CPP apparatus
bush, with the height of 2–6 m tall with numerous wide elliptical leaves [9]. It has gained a wide attention globally due to its multifaceted therapeutic benefits. The different parts of Noni such as roots, stems, leaves, barks, flowers and fruits are used to treat cancer, cardiovascular illness (heart disease, hypertension and atherosclerosis), mental illness (depression, anxiety and psychosis), muscle aches, diabetes, sprains, gastric ulcers, poor digestion, menstrual difficulties, sprains and drug addiction [10]. In recent years, the consumption of Noni fruit juice has gradually increased globally, especially, in the South Pacific Island to treat a wide range of diseases [11]. In a recent report, MMC has been shown to attenuate ethanol CPP in mice [12] and heroin CPP in rats [13] and suggested of its therapeutic potential against alcohol and heroin dependence. In continuation to these recent reports, the present study has made a first attempt in investigating the mitigating effect of MMC against Meth dependence using a mouse model of CPP. Several drugs such as BUPR are known as appealing medication for the treatment of methamphetamine dependence. In various clinical and preclinical studies, BUPR has been reported for its therapeutic effect against methamphetamine dependence [14–16]. BUPR is used in this study as a reference drug to compare the efficacy of the candidature drug. CPP paradigm is considered as a well-established and reliable animal model to study the rewarding effect of different drugs of abuse, including Meth [17]. CPP protocol primarily consists of three phases (i) acquisition/expression (ii) extinction and (iii) reinstatement. These three phases of CPP mimic the clinical situation of craving, abstinence, and relapse, respectively [18]. The aim of the present study was to determine the appropriate dose of Meth to induce conditioned place preference (CPP) in mice in our laboratory and to examine the effect of MMC and BUPR against the expression, extinction and reinstatement of Meth-induced CPP in mice.
CPP apparatus used for this study was a plexiglass box with the following specifications: 45(L) × 15(W) × 15(H) cm. With an insertion of two detachable plexiglass partitions, a small middle gray compartment measuring 5 × 15 × 15 cm is used to separate the CPP apparatus into two equal sized outer compartments (20 × 15 × 15 cm). The equal sized compartments were black and white compartment with different visual and tactile cues. The white compartment had white walls with black vertical stripes with a white wire mesh base while the black compartment had black walls with white horizontal stripes with a black smooth plexiglass base. To close off both white and black compartments, matched detachable plexiglass partitions were used. The plexiglass lid was designed to be transparent to monitor the animals’ behaviour on a computer linked to a Logitech HD webcam set over the CPP box. The animals’ behaviour was then displayed on the computer and later scored by an observer who was blind to the treatment protocol. The CPP methodology was separated into three different phases: acquisition/expression, extinction and reinstatement. The experiments were performed in a quiet experimental room and carried out during the same session of each day (0800–1600) for the purpose of increasing accuracy of experimental results.
2.5. Determination of an appropriate dose of Meth to induce CPP in mice 2.5.1. Habituation, and preconditioning The mice were subjected to 3 days of habituation and 1 day of preconditioning in the CPP test box. During the habituation period, each mouse was confined in the centre gray compartment for 5 min, both detachable partitions were then removed to allow the mice to freely access both compartments for 15 min. On the preconditioning day, animals were subjected in the same manner similar to habituation, with the time being spent in each compartment noted. The conditioning score was calculated by subtracting time spent by the animals in the white compartment from time spent by the animals in the black compartment and this served as a preconditioning baseline as described previously [13]. In this study, the white compartment was paired with Meth, while the black compartment was paired with saline.
2. Material and methods 2.1. Preparation and phytochemical characterization of MMC MMC was prepared by cold extraction with sonication techniques, as referred to our previous report [19]. The phytochemical profiling details of MMC were reported in our recent article [20]. 2.2. Drugs and chemicals
2.5.2. Conditioning After preconditioning, the mice were subjected to 10 days of conditioning with Meth or saline in the CPP box. During each day of conditioning, Meth group (n = 7–8 per group) received an intraperitoneal injection of Meth (0.5 or 1.0 or 2.0 mg/kg bw, i.p.) and saline (10 ml/kg bw, i.p.) on alternate days (Meth on odd days and saline on even days) in white and black compartment, respectively, and confined for 30 min in the respective compartment whereas the saline control group received saline in both compartments on both days. After 30 min of conditioning, the mice were sent to their home cages.
Methamphetamine hydrochloride (Sigma-Aldrich, St.Louis, MO, USA) was dissolved in sterile normal saline and it was administered intraperitoneally in the fixed volume of 10 ml/kg body weight of mice. MMC and bupropion (LKT Laboratories, St. Paul MN) were suspended in 1%w/v of sodium carboxymethyl cellulose (CMC) solution and were administered orally (p.o). CMC per se treated group served as a vehicle control. 2.3. Animals Male ICR mice of 7–8 weeks age, weighing 25–30 g, obtained from University Kebangsaan Malaysia (UKM) were housed in polycarbonate cages (4–5 animals per cage) enriched by introducing shredded paper at controlled temperature of 20–22 °C and humidity of 45–60%. The animals were obtained two weeks before use and were maintained at 12-h light: 12-h dark cycle (lights on at 7 AM). During the period of experimentation, animals were given unrestricted access to food pellets and purified drinking water. All animals were properly handled with at least one week before the experiment started. Proper animal care was given to reduce stress on the animals. The experimental protocols were assessed and validated by the Institutional Animal Care and Use Committee, Faculty of Medicine, University of Malaya, Kuala Lumpur (Approval No. 2016-190908/PHAR/R/VP).
2.5.3. Postconditioning One day after the last conditioning (Day 15), the mice were allowed to rest (no experiment was performed). On day 16 (48 h after the last conditioning session), postconditioning test was performed as described for preconditioning test. On this day, the mice were given neither saline nor Meth so they were in drug free state. Each mouse in the Meth-free state was placed in the centre gray compartment for 5 min and allowed freely to access between both compartments for 15 min. The time spent in each compartment was recorded and conditioning score was determined and denoted as postconditioning score.
369
Biomedicine & Pharmacotherapy 107 (2018) 368–373
V. Pandy et al.
2.6. Evaluation of the effect of MMC and bupropion on expression, extinction, and reinstatement of Meth (0.5 mg/kg)-induced CPP, respectively, in mice 2.6.1. Habituation, preconditioning, conditioning and postconditioning The experimental protocol was followed as described in the previous experiment for the appropriate dose determination. 2.6.2. Effect of MMC and BUPR on expression of 0.5 mg/kg Meth-induced CPP To study the effect of vehicle (CMC), BUPR and MMC on the rewarding properties of Meth, a different set of mice (n = 7–8 per group) were administered orally with 20 mg/kg of BUPR or 1, 3, and 5 g/kg of MMC or 10 ml/kg of 1% w/v CMC on post conditioning day (Day 16) respectively, 60 min prior to the CPP testing.
Fig. 1. Effect of Meth (0.5, 1.0 and 2.0 mg/kg, i.p.) on the conditioning score of CPP test in mice. Data are indicated as the mean difference ( ± SEM) between the time spent in the Meth-paired compartment and the time spent in the compartment paired with saline (n = 7–8/group). There was a significant difference (***p < 0.001) when compared between preconditioning and postconditioning scores. When not indicated, the difference was not statistically significant.
2.6.3. Extinction of Meth-induced CPP Extinction tests were carried out for 5 days (day 17–day 21) from next day of postconditioning which consisted of daily 15 min CPP testing as described for postconditioning test and the conditioning scores were determined. Neither Meth nor the saline intraperitoneal injection (i.p.) was given during this extinction session.
2.8. Statistical analysis All data are presented as mean ± SEM. Statistical analysis was done by GraphPad Prism 5 statistical software using a mixed two-factor (Group × Session) repeated measures two-way ANOVA for CPP studies followed by post hoc Bonferroni test (preconditioning versus postconditioning) and one-way ANOVA for locomotor activity followed by a post hoc Dunnett’s multiple comparisons test. The values of p < 0.05 were set as statistically significant.
2.6.4. Effect of MMC and BUPR on extinction of 0.5 mg/kg Meth-induced CPP To study the effect of vehicle (CMC), MMC and BUPR on the extinction of Meth-induced CPP, the animals were distinguished into two groups (saline-treated and Meth-treated) which were subjected to preconditioning, conditioning and postconditioning phase as mentioned above. The CPP-induced Meth animals were further divided into vehicle, BUPR and MMC -treated groups (n = 6–7 per group) which received orally with 20 mg/kg BUPR or 1, 3, and 5 g/kg of MMC or 10 ml/ kg of 1% w/v CMC, respectively, 60 min prior to the CPP testing for 15 min during extinction 1 to extinction 5 (Day 17- Day 21).
3. Results 3.1. Determination of an appropriate dose of Meth to induce CPP in mice The different doses of Meth (0.5, 1 and 2 mg/kg, i.p.) were employed in CPP testing to find an appropriate dose of Meth to induce CPP in mice. The pre- and postconditioning results are presented in Fig. 1. A repeated measures two-way ANOVA results revealed a significant effect of Group [F (3, 26) = 3.593; P = 0.0269], Trial [F (1, 26) = 44.37; P < 0.0001] and Group × Trial interactions [F (3, 26) = 9.214; P = 0.0003]. A post hoc Bonferroni test (compared preconditioning versus postconditioning) revealed that Meth (0.5 and 1 mg/kg, i.p.) significantly (P < 0.001) increased the postconditioning scores when compared with its corresponding preconditioning scores which implies the induction of CPP with the effective doses of Meth (0.5 and 1 mg/kg, i.p.) in mice (Fig. 1). Interestingly, Meth at relatively higher dose 2 mg/ kg did not significantly alter the postconditioning score.
2.6.5. Reinstatement of Meth-induced CPP On day 22, a day after the last extinction trial, the test animals were allowed to rest (no experiment was conducted). On day 23 (48 h after the last extinction session), reinstatement test was performed. 2.6.6. Effect of MMC and BUPR on a low dose Meth-priming reinstatement of CPP To study the effect of MMC, BUPR and vehicle (CMC) on the reinstatement of Meth-induced CPP, the animals were divided into salinetreated and Meth-treated and were subjected to postconditioning and extinction trials for 5 days. Following one-day rest of the last extinction trial (Day 22), the treatment groups (n = 7–8 per group) received an oral gavage of 20 mg/kg BUPR or 1, 3, and 5 g/kg of MMC or 10 ml/kg of 1% w/v CMC respectively, 45 min prior to a priming injection of a low dose of Meth (0.1 mg/kg, i.p.). After 15 min of a priming Meth injection, animals were subjected to 15 min CPP testing as described for postconditioning test and the conditioning score was determined.
3.2. Effect of MMC and BUPR on expression of Meth-induced CPP in mice The effect of MMC and BUPR on expression of Meth-induced CPP in mice is presented in Fig. 2. A repeated measures two-way ANOVA results revealed a significant effect of Trial [F (1, 41) = 22.16; P < 0.0001] whereas Group [F (5, 41) = 1.11; P = 0.3699] and Group × Trial interaction [F (5, 41) = 2.04; P = 0.0928] were found to be insignificant. A post hoc Bonferroni test (compared preconditioning versus postconditioning) revealed that Meth (0.5 mg/kg, i.p.) significantly (p < 0.01) increased the postconditioning score when compared with its corresponding preconditioning score which implies the induction of CPP with a minimum effective dose of Meth (0.5 mg/ kg, i.p.) in mice. Similarly, MMC (1 g/kg)-treated group also showed a significant difference (p < 0.05) between its pre- and postconditioning scores which implies the inability of MMC at 1 g/kg to reduce the postconditioning score. Interestingly, MMC at 3 and 5 g/kg attenuated Meth-induced CPP in mice which is evident from non-significant difference between pre- and postconditioning scores. The reference drug,
2.7. Effect of MMC per se on spontaneous locomotor activity in mice The spontaneous locomotor activity was assessed using actimeter (Model: ACT-01, Orchid’s Scientific, Nasik, India) fabricated with clear square Plexiglas arena (50 cm × 50 cm), equipped with 32-infrared sensors. The mice were divided into four groups (N = 10) and administered with 1% CMC (10 ml/kg, p.o.) and MMC at different doses of 1, 3 and 5 g/kg, p.o., respectively, 60 min prior to the test. The spontaneous locomotor activity was assessed for 10 min in actimeter by placing the mouse in the centre arena. The data are expressed as the total light beam interruptions (locomotor counts) per 10 min. The floor of the apparatus was cleaned with 20% v/v ethanol between tests. 370
Biomedicine & Pharmacotherapy 107 (2018) 368–373
V. Pandy et al.
Fig. 2. Effect of MMC (1, 3 and 5 g/kg, p.o.) and BUPR (20 mg/kg, p.o.) on the expression of Meth-induced CPP in mice. Data are indicated as the mean difference ( ± SEM) between the time spent in the Meth-paired compartment and the time spent in the compartment paired with saline (n = 7–8/group). There was a significant difference (*P < 0.05; **P < 0.01) when compared between preconditioning and postconditioning scores. When not indicated, the difference was not statistically significant.
Fig. 4. Effect of MMC (1, 3 and 5 g/kg, p.o.) and BUPR (20 mg/kg, p.o.) on a low dose Meth (0.1 mg/kg, i.p.)-priming reinstatement of CPP in mice. Data are expressed as the mean difference ( ± SEM) between the time spent in Methcompartment and the time spent in the compartment paired with saline (n = 7–8/group).
BUPR (20 mg/kg) also attenuated Meth-induced CPP in mice (no significant difference between its pre- and postconditioning scores). 3.3. Effect of MMC and BUPR on the extinction of Meth-induced CPP in mice The effect of MMC and BUPR on the extinction of Meth-induced CPP is presented in Fig. 3. A repeated measures two-way ANOVA results revealed a non-significant effect of Group [F (5, 35) = 1.645; P = 0.1740], Trial [F (4, 140) = 0.4614; P = 0.7640], and Group × Trial interaction [F (20, 140) = 0.2513; P = 0.9996]. Meth-control group failed to demonstrate any noticeable preference for the Methpaired compartment during entire extinction trials (EXT 1 to EXT 5). Therefore, an expedite effect of treatment groups (MMC and BUPR) on the extinction of Meth-induced CPP in mice could not be determined.
Fig. 5. Effect of MMC (1, 3 and 5 g/kg, p.o.) per se on the spontaneous locomotor activity in mice. Data are presented as Mean ± SEM (n = 10/group). Statistical differences between vehicle (1%w/v CMC)-treated group with MMCtreated groups were analysed by one-way ANOVA followed by post hoc Dunnett’s test.
3.4. Effect of MMC and BUPR on a low dose Meth priming reinstatement of CPP The effect of MMC and BUPR on a low dose Meth priming-induced CPP is shown in Fig. 4. A repeated measures two-way ANOVA results revealed a non-significant effect of Group [F (5, 37) = 1.342; P = 0.2683], Trial [F (1, 37) = 0.03610; P = 0.8503] and Group × Trial Interaction [F (5, 37) = 2.233; P = 0.0715]. Meth-control group failed to show any significant noticeable preference for the Meth-paired compartment on post-reinstatement when compared with its pre-reinstatement. Therefore, the attenuating effect of treatment groups
(MMC and BUPR) on reinstatement of Meth-induced CPP could not be demonstrated in the present study. 3.5. Effect of MMC per se on spontaneous locomotor activity in mice As shown in Fig.5, MMC at all tested doses (1, 3 and 5 g/kg, p.o.) did not significantly affect the spontaneous locomotor activity in mice [F (3, 36) = 1.806; P = 0.1635]. 4. Discussion The effectiveness of MMC and BUPR on the rewarding properties of Meth was systematically evaluated using a mouse model of CPP test in this study. CPP is a standard and reliable behavioural model to study the rewarding effect of various drugs of abuse, including Meth, that is usually associated with the classical Pavlovian conditioning [13]. It has been well documented that the principles of CPP involve the association of learning and memory. Glutamatergic system has been found as a critical neurochemical determinant in various learning and memory animal models including CPP test [17]. The first experiment investigated the appropriate minimum dose of Meth to induce conditioned place preference in mice. The result of the first experiment demonstrated that Meth at doses (0.5 and 1 mg/kg, i.p.) significantly (P < 0.001) induced CPP in mice (Fig. 1). This result corroborates with an earlier published report in which CPP was
Fig. 3. Effect of MMC (1, 3 and 5 g/kg, p.o.) and BUPR (20 mg/kg, p.o.) on the extinction of Meth CPP in mice. Data are expressed as the mean difference ( ± SEM) between the times spent in the Meth-paired compartment and time spent in compartment paired with saline (n = 6–7/group). 371
Biomedicine & Pharmacotherapy 107 (2018) 368–373
V. Pandy et al.
in the market to treat drug dependence (e.g., alcohol, heroin, and nicotine) are reported for their ability to weaken the expression of druginduced CPPs in mice and rats [13,27,28]. Recently, our research group demonstrated that MMC mitigated the expression of heroin-induced CPP and ethanol-induced CPP in rats and mice respectively [13,12]. In the present study, MMC was found to attenuate the expression of Methinduced CPP in mice. These reports revealed the therapeutic potential of MMC against drug dependence and it could be utilized for novel drug discovery in the treatment of drug dependence. Some drugs may show positive results in CPP test, not by acting on the reward pathway, but by simply impairing the learning and memory. For instance, NMDA receptor antagonists were found to exhibit a false positive result in the CPP test [29]. Interestingly, it has been revealed a nootropic effect of M. citrifolia fruit extract in scopolamine-induced memory impairment in mice [30]. Similarly, the ethyl acetate extract of noni fruit reversed the memory impairment induced by beta amyloid in mice [31]. Therefore, the mitigating effect of MMC against Meth-induced CPP could not be mediated through memory impairment mechanism. Other than that, drugs that impair the movement of animals can affect CPP outcome. Nevertheless, there was no alteration in motor activity of mice when the mice were treated with MMC (1, 3 and 5 g/kg, p.o.) per se as shown in Fig. 5 and this result was corroborated with an earlier report on locomotor activity in which noni fruit extract when treated for 21 days did not alter the spontaneous locomotor activity [30] which implies the effect of MMC on Meth-induced CPP was not mediated through motor alterations in mice. Furthermore, an acute oral toxicity study of MMC revealed that no toxic effects of MMC were discovered up to a dose of 20 g/kg in mice [19]. According to OECD guidelines, the extracts which do not exhibit toxic effects up to 2 g/kg, p.o., should be considered safe. The neuronal or neurochemical mechanism underlying the mitigating effect of MMC on expression of Meth-induced CPP in mice were not focused in this study. However, our research group had established the antidopaminergic effect of MMC using in vivo [19] and ex vivo studies [20]. Therefore, we hypothesize that the mitigating effect of MMC against Meth-induced expression of CPP in mice could originate from its antidopaminergic activity. Generally, noni fruit has been suggested to have multiple therapeutic benefits due to its multiple phytoconstituents, such as scopoletin and rutin that are responsible for its antidopaminergic activity [32,33]. Our research group also had performed the phytochemical analysis of MMC and it has been reported that the main phytoconstituents of MMC were characterized and liberated as scopoletin (18.95 μg/mg) and rutin (1.66 μg/mg) [20]. In addition, a previous study postulated that scopoletin and rutin are important in antidopaminergic activity of noni [34]. Moreover, scopoletin and rutin were reported for its interaction with dopamine D2 and D3 receptors in in silico molecular docking studies [35]. It has been postulated that a selective dopamine D3 receptor antagonist could be used to alleviate drug-induced motivation and reward [35]. Although the present work could not confirm the involvement of the bioactive principles of noni, scopoletin and rutin for its mitigating effect against Meth-induced CPP, it has been postulated that these phytoconstituents could be responsible for the mitigating effect of MMC. However, further preclinical studies using scopoletin and rutin per se are warranted in the novel drug discovery for the treatment of Meth dependence. Currently, no FDA-approved drug is available for treating Meth dependence, however, this study utilized BUPR as a reference drug to attenuate Meth-induced CPP in mice. BUPR is an antidepressant and also an approved FDA drug to treat nicotine dependence. Successful offlabel use of this drug to treat Meth-addicts prompted investigators for further studies. BUPR was reported to attenuate Meth self-administration in rats [16]. BUPR is a monoamine uptake inhibitor and inhibits reuptake of dopamine and norepinephrine [36]. Chronic Meth use destroys dopaminergic neurons and results in low dopaminergic tone. The BUPR blocks presynaptic dopamine transporter (DAT) and therefore
significantly induced at a lower dose of 0.5 mg/kg Meth in mice [21]. Interestingly, Meth at a relatively higher dose (2.0 mg/kg, i.p.) failed to demonstrate CPP in mice (Fig. 1). This indicates that the expression of Meth CPP can be achieved only at doses lower than 2 mg/kg. In line with the present findings, an earlier study report demonstrated an inverted U-shaped dose response curve in Meth-induced CPP in mice and suggested the ineffectiveness of Meth at higher doses to induce CPP [22]. The expression of Meth-induced CPP involves association of the rewarding properties of the drug and the environmental cues correlated with it. In this study, the rewarding properties of Meth associated with the environmental cues (white compartment) and tactile cues (mesh floor) lead to preference of the animals to be in the white compartment during postconditioning session. Though Meth significantly induced CPP at 0.5 and 1.0 mg/kg doses, the minimum effective dose of Meth (i.e., 0.5 mg/kg, i.p.) was chosen for the present study. The second experiment was aimed to investigate the effect of MMC against 0.5 mg/kg Meth-induced CPP at different phases of place conditioning such as expression, extinction and reinstatement, mimicking the actual clinical situation of craving, abstinence and relapse, respectively [12]. The results of the second experiment revealed that intraperitoneal administration of Meth (0.5 mg/kg) significantly (p < 0.01) induced CPP in mice (Fig. 2). Interestingly, MMC (3 and 5 g/kg) and BUPR (20 mg/kg) attenuated the expression of Meth (0.5 mg/kg)-induced CPP in mice which was evident from non-significant differences between respective pre- and post-conditioning scores (Fig. 2). However, the present study failed to achieve a significant gradual weakening of CPP by repeated exposure of animals in Meth-free state in the place conditioning environment (Fig. 3). This study also failed to achieve a significant reinstatement by administration of a priming, low dose of Meth (0.1 mg/kg) in Meth-extinct mice (Fig. 4). Due to the unsuccessful establishment of extinction and reinstatement of Meth-induced CPP in the present study, the effect of MMC and BUPR on these phases of CPP could not be determined. Based on the present study results, it has been postulated that Meth (1 mg/kg, i.p.) could be used to induce a significant Meth-CPP in mice and 1/5th of the conditioning dose (i.e., 0.2 mg/kg, i.p.) could be used for establishing reinstatement in Meth-extinct mice. Further studies in this direction are warranted for successful establishment of all phases (expression, extinction and reinstatement) of Meth-induced CPP in mice. Addiction is characterized as compulsive drug seeking behaviour and often related to the chronic consumption of drugs of abuse such as alcohol, cocaine and Meth [13]. Meth passes through the nerve cell membrane directly and enters the nerve terminals [23]. It binds to the vesicular monoamine transporter (VMAT) of the dopamine vesicles and forces the dopamine out of the vesicle to the cytoplasm. Meth also reverses the direction flow of dopamine transporter, leads to release of the dopamine neurotransmitter from the cytoplasm to the synapse, and causes increased in the binding of dopamine to post-synaptic receptors. Moreover, the reuptake of dopamine neurotransmitter is inhibited by Meth, giving rise to an abundance of dopamine remaining in the synapse for a prolonged period and activating the dopamine receptors [23]. Meth works directly on the brain’s reward mechanism and therefore it is highly addictive. The release of dopamine from ventral tegmental area into the nucleus accumbens promotes a positive reinforcement that stimulates the person to repeat the pleasant experience and lead to Meth dependence [24]. Previously, reports of singlephoton emission computed tomography (SPECT) and positron emission tomography (PET) in Meth-addicted users revealed a decline in the number of D2 receptors within the ventral striatum area that remained after a lengthened period of detoxification [25]. In addition, there has been a previous report regarding the administration of D₂ receptor antagonists able to reduce drug self-administration in rat [26]. Thus, it can be hypothesized that the neuromodulatory effect of drugs on dopaminergic system, possibly benefit in the drug addiction therapy. The drugs (e.g., acamprosate, methadone, and bupropion) available 372
Biomedicine & Pharmacotherapy 107 (2018) 368–373
V. Pandy et al.
prevents Meth from acting with DAT and antagonize the effect of Meth. BUPR is able to elevate the concentration of dopamine in the synaptic cleft and maintains the homeostasis of dopamine concentration [37]. BUPR has also been shown to reduce the dopamine reuptake and neurotoxic effects of Meth in rats [16]. Furthermore, a double-blind and placebo-controlled clinical trial evaluating the efficacy between placebo and BUPR (300 mg/d) showed that BUPR is effective in attenuating the Meth withdrawal syndrome in patients and therefore it reduced the use of Meth [38].
Pharmacol. 7 (2016) 352. [13] M. Narasingam, V. Pandy, Z. Mohamed, Noni (Morinda citrifolia L.) fruit extract attenuates the rewarding effect of heroin in conditioned place preference but not withdrawal in rodents, Exp. Anim. 65 (2) (2016) 157–164. [14] T.F. Newton, J.D. Roache, R. De La Garza 2nd, T. Fong, C.L. Wallace, S.H. Li, A. Elkashef, N. Chiang, R. Kahn, Bupropion reduces methamphetamine-induced subjective effects and cue-induced craving, Neuropsychopharmacology 31 (7) (2006) 1537–1544. [15] C.M. Reichel, J.D. Linkugel, R.A. Bevins, Bupropion differentially impacts acquisition of methamphetamine self-administration and sucrose-maintained behavior, Pharmacol. Biochem. Behav. 89 (3) (2008) 463–472. [16] C.M. Reichel, J.E. Murray, K.M. Grant, R.A. Bevins, Bupropion attenuates methamphetamine self-administration in adult male rats, Drug Alcohol Depend. 100 (1-2) (2009) 54–62. [17] Z. He, Y. Chen, H. Dong, R. Su, Z. Gong, L. Yan, Inhibition of vesicular glutamate transporters contributes to attenuate methamphetamine-induced conditioned place preference in rats, Behav. Brain Res. 267 (2014) 1–5. [18] S.T. Pittenger, Examination of Methamphetamine Reinstatement in Female and Male Rats: A Pre-Clinical Model of Relapse, Pro Quest Dissertations & Theses Global, Retrieved from (2016) http://ezproxy.um.edu.my:2048/login?url=https:// search.proquest.com/docview/182325692?accountid=28930. [19] V. Pandy, M. Narasingam, Z. Mohamed, Antipsychotic-like activity of noni (Morinda citrifolia Linn.) in mice, BMC Complement. Altern. Med. 12 (2012) 186. [20] V. Pandy, M. Narasingam, T. Kunasegaran, D.D. Murugan, Z. Mohamed, Effect of noni (Morinda citrifolia Linn.) fruit and its bioactive principles scopoletin and rutin on rat vas deferens contractility: an ex vivo study, Sci. World J. 2014 (2014) 909586. [21] N. Kitanaka, J. Kitanaka, F.S. Hall, G.R. Uhl, K. Watabe, H. Kubo, H. Takahashi, M. Takemura, Attenuation of methamphetamine-induced conditioned place preference in mice after a drug-free period and facilitation of this effect by exposure to a running wheel, J. Exp. Neurosci. 6 (2012) 11–19. [22] C. Achat-Mendes, S.F. Ali, Y. Itzhak, Differential effects of amphetamines-induced neurotoxicity on appetitive and aversive pavlovian conditioning in mice, Neuropsychopharmacology 30 (6) (2005) 1128–1137. [23] R.B. Rothman, M.H. Baumann, C.M. Dersch, D.V. Romero, K.C. Rice, F.I. Carroll, J.S. Partilla, Amphetamine-type central nervous system stimulants release norepinephrine more potently than they release dopamine and serotonin, Synapse 39 (1) (2001) 32–41. [24] G.F. Koob, F.E. Bloom, Cellular and molecular mechanisms of drug dependence, Science 242 (4879) (1988) 715–724. [25] N.D. Volkow, L. Chang, G.J. Wang, J.S. Fowler, Y.S. Ding, M. Sedler, J. Logan, D. Franceschi, J. Gatley, R. Hitzemann, A. Gifford, C. Wong, N. Pappas, Low level of brain dopamine D2 receptors in methamphetamine abusers: association with metabolism in the orbitofrontal cortex, Am. J. Psychiatry 158 (12) (2001) 2015–2021. [26] W.J. Eiler, H.L. June, Blockade of GABA(A)A receptors within the extended amygdala attenuates D 2 regulation of alcohol-motivated behaviors in the ventral tegmental area of alcohol-preferring (P) rats, Neuropharmacology 52 (8) (2007) 1570–1579. [27] M.I. Damaj, S.D. Grabus, H.A. Navarro, R.E. Vann, J.A. Warner, L.S. King, J.L. Wiley, B.E. Blough, R.J. Lukas, F.I. Carroll, Effects of hydroxymetabolites of bupropion on nicotine dependence behavior in mice, J. Pharmacol. Exp. Ther. 334 (3) (2010) 1087–1095. [28] A.J. Mcgeehan, M.F. Olive, The anti‐relapse compound acamprosate inhibits the development of a conditioned place preference to ethanol and cocaine but not morphine, Br. J. Pharmacol. 138 (1) (2003) 9–12. [29] M.A. Aguilar, C. Manzanedo, B.R. Do Couto, M. Rodríguez-Arias, J. Miñarro, Memantine blocks sensitization to the rewarding effects of morphine, Brain Res. 1288 (2009) 95–104. [30] S.D. Pachauri, P.R. Verma, A.K. Dwivedi, S. Tota, K. Khandelwal, J.K. Saxena, C. Nath, Ameliorative effect of noni fruit extract on streptozotocin-induced memory impairment in mice, Behav. Pharmacol. 24 (4) (2013) 307–319. [31] P. Muralidharan, V.R. Kumar, G. Balamurugan, Protective effect of Morinda citrifolia fruits on β‐amyloid (25–35) induced cognitive dysfunction in mice: an experimental and biochemical study, Phytother. Res. 24 (2) (2010) 252–258. [32] V. Pandy, K. Vijeepallam, Antipsychotic-like activity of scopoletin and rutin against the positive symptoms of schizophrenia in mouse models, Exp. Anim. 66 (4) (2017) 417–423. [33] Y. Chan-Blanco, F. Vaillant, A.M. Perez, M. Reynes, J.-M. Brillouet, P. Brat, The noni fruit (Morinda citrifolia L.): a review of agricultural research, nutritional and therapeutic properties, J. Food Compost. Anal. 19 (6) (2006) 645–654. [34] S. Deng, B. West, A. Palu, B. Zhou, C. Jensen, Noni as an anxiolytic and sedative: a mechanism involving its gamma-aminobutyric acidergic effects, Phytomedicine 14 (7) (2007) 517–522. [35] S. Jeyabalan, K. Subramanian, U.M.R. Cheekala, C. Krishnan, GC–MS analysis and in-silico antipsychotic activity of Morinda citrifolia (Indian noni), J. Appl. Pharm. Sci. 7 (4) (2017) 89–95. [36] L. Karila, A. Weinstein, H.J. Aubin, A. Benyamina, M. Reynaud, S.L. Batki, Pharmacological approaches to methamphetamine dependence: a focused review, Br. J. Clin. Pharmacol. 69 (6) (2010) 578–592. [37] L.D. Simmler, R. Wandeler, M.E. Liechti, Bupropion, methylphenidate, and 3, 4methylenedioxypyrovalerone antagonize methamphetamine-induced efflux of dopamine according to their potencies as dopamine uptake inhibitors: implications for the treatment of methamphetamine dependence, BMC Res. Notes 6 (1) (2013) 220. [38] I.D. Montoya, F. Vocci, Novel medications to treat addictive disorders, Curr. Psychiatry Rep. 10 (5) (2008) 392–398.
5. Conclusion Meth exhibits the expression of CPP at a minimum effective dose of 0.5 mg/kg (i.p.), however, it fails to demonstrate a significant extinction and reinstatement of Meth-induced CPP in mice. This study also demonstrates that MMC (3 and 5 g/kg, p.o.) and BUPR (20 mg/kg, p.o.) mitigated the expression of Meth-induced CPP in mice. This implies that MMC attenuated the rewarding properties of Meth which could be utilized to treat Meth dependence. The results of this study could pave the way for other researchers to discover an effective pharmacotherapy for the treatment of Meth dependence. Further clinical studies using MMC are required to assist these preclinical findings and to treat Meth dependence. Funding This study was supported by the University of Malaya Research grants (BKS051-2017; PG232-2015B and PG023-2014B). The funding sources granted for this work were not involved in study design, in the collection, analysis and interpretation of data, in the writing of the report, and in the decision to submit the article for publication. Conflict of interests The authors declare that they have no competing interests. Acknowledgement The authors thank Prof Nor Azizan Abdullah for proofread of this manuscript. References [1] J.J. Nocon, Substance use disorders, in: D.R. Mattison (Ed.), Clinical Pharmacology During Pregnancy, Academic Press, London, 2013, pp. 217–256. [2] Q.T. Chie, C.L. Tam, G. Bonn, C.P. Wong, H.M. Dang, R. Khairuddin, Drug abuse, relapse, and prevention education in Malaysia: perspective of university students through a mixed methods approach, Front. Psychiatry 6 (2015) 65. [3] S. Yu, L. Zhu, Q. Shen, X. Bai, X. Di, Recent advances in methamphetamine neurotoxicity mechanisms and its molecular pathophysiology, Behav. Neurol. 2015 (2015) 103969. [4] B.M. Kuehn, Meth use linked to risk of parkinson disease, JAMA 306 (8) (2011) 814. [5] M.E. Mattson, Emergency Department Visits Involving Methamphetamine: 2007 to 2011, The CBHSQ Report, Substance Abuse and Mental Health Services Administration (US), Rockville (MD), 2013, pp. 1–7. [6] AADK, MAKLUMAT DADAH 2015., Agensi Antidadah Kebangsaan Kementerian Dalam Negeri (2015). [7] A.T. McLellan, D.C. Lewis, C.P. O’Brien, H.D. Kleber, Drug dependence, a chronic medical illness: implications for treatment, insurance, and outcomes evaluation, JAMA 284 (13) (2000) 1689–1695. [8] P.R. Kufahl, M.F. Olive, Investigating methamphetamine craving using the extinction-reinstatement model in the rat, J. Addict. Res. Ther. 1 (3) (2011) 003. [9] W. McClatchey, From polynesian healers to health food stores: changing perspectives of Morinda citrifolia (Rubiaceae), Integr. Cancer Ther. 1 (2) (2002) 110–120. [10] V. Samoylenko, J. Zhao, D.C. Dunbar, I.A. Khan, J.W. Rushing, I. Muhammad, New constituents from noni (Morinda citrifolia) fruit juice, J. Agric. Food Chem. 54 (17) (2006) 6398–6402. [11] B.J. West, C.J. Jensen, J. Westendorf, L.D. White, A safety review of noni fruit juice, J. Food Sci. 71 (8) (2006) R100–R106. [12] Y. Khan, V. Pandy, Methanolic extract of Morinda citrifolia L. (noni) unripe fruit attenuates ethanol-induced conditioned Place preferences in mice, Front.
373