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Peony glycosides reverse the effects of corticosterone on behavior and brain BDNF expression in rats
Behavioural Brain Research 227 (2012) 305–309
Contents lists available at SciVerse ScienceDirect
Behavioural Brain Research journal homepage: www.elsevier.com/locate/bbr
Short communication
Peony glycosides reverse the effects of corticosterone on behavior and brain BDNF expression in rats Qing-Qiu Mao a , Zhen Huang b , Siu-Po Ip a,∗ , Yan-Fang Xian a , Chun-Tao Che c a b c
School of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong College of Pharmacy, Zhejiang Chinese Medicine University, Hangzhou, 310053 Zhejiang, China Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, IL 60612, USA
a r t i c l e
i n f o
Article history: Received 9 October 2011 Received in revised form 8 November 2011 Accepted 12 November 2011 Available online 19 November 2011 Keywords: Antidepressant Brain-derived neurotrophic factor Corticosterone Peony glycosides Rat
a b s t r a c t Repeated injections of corticosterone (CORT) induce the dysregulation of the hypothalamic-pituitaryadrenal (HPA) axis, resulting in depressive-like behavior. This study aimed to examine the antidepressantlike effect and the possible mechanisms of total glycosides of peony (TGP) in the CORT-induced depression model in rats. The results showed that the 3-week CORT injections induced the significant increase in serum CORT levels in rats. Repeated CORT injections also caused depression-like behavior in rats, as indicated by the significant decrease in sucrose consumption and increase in immobility time in the forced swim test. Moreover, it was found that brain-derived neurotrophic factor (BDNF) protein levels in the hippocampus and frontal cortex were significantly decreased in CORT-treated rats. Treatment of the rats with TGP significantly suppressed the depression-like behavior and increased brain BDNF levels in CORT-treated rats. The results suggest that TGP produces an antidepressant-like effect in CORT-treated rats, which is possibly mediated by increasing BDNF expression in the hippocampus and frontal cortex. © 2011 Elsevier B.V. All rights reserved.
Depression is a commonly occurring, debilitating, and lifethreatening psychiatric disorder. Based on latest available data from the World Health Organization, depression is expected to become the second leading cause of disease-related disability by the year 2020. Although the monoamine theory of depression has been extensively investigated, it is unable to fully explain the pathophysiology of depression [33]. In recent years, a substantial amount of experimental and clinical data has supported the notion that dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is involved in the pathogenesis of depression [33]. The HPA axis is activated in response to stress, which results in increased concentrations of glucocorticoids in the circulating blood. Under normal conditions, blood glucocorticoid level is tightly regulated by a negative feedback mechanism. However, high concentrations of blood glucocorticoids are reportedly maintained in patients with depression due to a dysfunction in the feedback mechanism [17,33]. More importantly, high levels of glucocorticoids have been demonstrated to induce depressive-like behavior in rodents, as indicated by the significant decrease in sucrose consumption, and increase in immobility time in forced swim tests and tail suspension tests; these changes, however, are significantly reversed by antidepressants and acupuncture treatment [4,6,18]. Treatment with high levels of glucocorticoids have
∗ Corresponding author. Tel.: +852 3163 4457; fax: +852 3163 4459. E-mail address: [email protected] (S.-P. Ip). 0166-4328/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.bbr.2011.11.016
also been found to produce changes in neurochemistry and brain anatomy, all of which may be related to depression [7,17,25]. These findings suggest that a glucocorticoid-induced depression model in rodents is valid for evaluating the efficacy of potential antidepressants and explore the mechanism of action of antidepressants [10,11,15,40]. The root part of Paeonia lactiflora Pall. (Ranunculaceae), commonly known as peony, is a commonly used medicinal herbs in China, Korea and Japan. A recent study in our laboratory has demonstrated the antidepressant effect of peony in the mouse model of behavioral despair [20]. Glycosides, including paeoniflorin and albiflorin, are known to be the biologically active ingredients of peony, and the total glycosides fraction of peony has been shown to possess anti-inflammatory, antioxidant, anti-hepatic fibrosis, antidiabetic and renoprotective properties [32,35,36,39,41]. Studies from our laboratory also showed that the intragastric administration of total glycosides of peony (TGP) caused a significant reduction of immobility time in both forced swim and tail suspension tests in mice [21]. The antidepressive effect of TGP was also observed in mice and rats exposed to chronic unpredictable stress, which were related to the modulation of the hypothalamicpituitary-adrenal axis function, the inhibition of oxidative stress, and the up-regulation of neurotrophins expression [22–24]. However, there is no information about the antidepressant-like effect of TGP in the glucocorticoid-induced depression model. Therefore, in this study, the antidepressant-like effect of TGP treatment was further evaluated in a rat model of depression induced by
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corticosterone (CORT), a principal glucocorticoid. Given that BDNF is involved in the molecular pathophysiology of depression and upregulation of its expression may contribute to the action of antidepressants [13,14,19,31,37], we also investigated whether the antidepressant-like effect of TGP in CORT-treated rats was related to the upregulation of BDNF expression by measuring BDNF protein levels in brain tissues. Male Sprague-Dawley rats weighing 200–220 g were obtained from the Laboratory Animal Services Center, The Chinese University of Hong Kong, Hong Kong. The animals were maintained on a 12-h light/dark cycle under controlled temperature conditions (22 ± 2 ◦ C) and given standard food and water ad libitum. The rats were allowed to acclimatize for 3 days before the experiments. The animal experiments have been approved by the Animal Experimentation Ethics Committee of the Chinese University of Hong Kong, and they conform to the guidelines of the “Principles of Laboratory Animal Care” (NIH publication No.80-23, revised 1996). Efforts were made to minimize the number and suffering of the animals. TGP (light yellow brown powder) was supplied by Ningbo Liwah Pharmaceutical Co., Ltd. (Zhejiang, China). TGP has been characterized by high-performance liquid chromatography in our previous studies [21–24] which mainly contains paeoniflorin and albiflorin. A voucher sample (TGP071024) was deposited in the School of Chinese Medicine for future reference. CORT and fluoxetine (a selective serotonin reuptake inhibitor, used as positive control) were purchased from Sigma–Aldrich (St Louis, MO, USA). The rats were divided into four groups of seven animals in each: vehicle control group, CORT plus vehicle group, CORT plus TGP (160 mg/kg) group and CORT plus fluoxetine (20 mg/kg) group. CORT (40 mg/kg, dissolved in saline containing 0.1% dimethyl sulfoxide and 0.1% Tween-80) was administrated subcutaneously (s.c.) in a volume of 5 ml/kg once daily for 21 days. TGP and fluoxetine were administered intragastrically (p.o.) in a volume of 10 ml/kg 30 min prior to the CORT injection for 21 days. The doses of TGP [24] and fluoxetine [8,30] were chosen based on our previous study and previously published reports. The sucrose preference test was carried out 24 h after the last drug treatment. The test was performed as described previously [24], with minor modifications. Before the test, the rats were trained to adapt to sucrose solution (1%, w/v) by placing two bottles of sucrose solution in each cage for 24 h; then one of the bottles was replaced with water for 24 h. After the adaptation procedure, the rats were deprived of water and food for 24 h. The sucrose preference test was conducted at 9:00 a.m. The rats were housed in individual cages and given free access to the two bottles containing 100 ml of sucrose solution (1%, w/v) and 100 ml of water, respectively. After 3 h, the volumes of consumed sucrose solution and water were recorded and the sucrose preference was calculated by the following formula: sucrose consumption Sucrose preference = water consumption+sucrose × consumption 100. The forced swim test was carried out 48 h after the sucrose preference test. The test was performed according to the method by Porsolt et al. [26] with minor modifications. As a pre-test, the rats were individually forced to swim for 15 min in a vertical plastic cylinder (diameter 21 cm, height 50 cm) containing 25 cm of water, maintained at 25 ± 1 ◦ C. The rats were then removed and dried before being returned to cages. After 24 h, the rats were again placed in the cylinders in the same system depicted above. The total duration of immobility (s) was quantified during a test period of 5 min by two observers who were blind to the treatment given to each rat. A rat was considered immobile whenever it remained floating passively in a slightly hunched but upright position with its head just above the surface.
Table 1 Serum CORT levels in different groups. Treatment
CORT level (ng/ml)
Control CORT + vehicle CORT + TGP CORT + fluoxetine
49.0 120.5 69.7 88.3
± ± ± ±
3.5 10.7# 9.7** 7.5*
Values given are the mean ± SEMs (n = 6). # p < 0.01 compared with the control group. * p < 0.05 compared with the CORT group. ** p < 0.01 compared with the CORT group.
Twenty-four hours after the forced swim test, the rats were sacrificed by decapitation and the blood samples were collected in tubes. Serum was separated by centrifugation at 4000 × g for 10 min and stored at −80 ◦ C until assay. Whole brains were rapidly removed from rats and chilled in an ice-cold saline solution. Various brain areas, including the hippocampus and frontal cortex, were dissected on a cold plate, and immediately frozen in liquid nitrogen. The tissue samples were stored at −80 ◦ C until assay. Serum corticosterone level was measured using a commercially available enzyme-linked immunosorbent assay (ELISA) kit (Assay Designs, Inc., Michigan) according to the manufacturer’s protocol. Briefly, samples, corticosterone standard, corticosterone EIA conjugate and corticosterone EIA antibody were applied into a 96-well plate precoated with donkey anti-Sheep IgG and incubated on a shaker for 2 h at room temperature. Then pNpp substrate solution was added and incubated at room temperature for 1 h after three washes. The reaction was stopped with trisodium phosphate and absorbance was recorded at 405 nm immediately. The detection limit of the assay is ∼27 pg/ml. The BDNF content in the hippocampus and frontal cortex was measured using a commercially available enzyme-linked immunosorbent assay kit (Chemicon International, Temecula, CA) according to the manufacturer’s instructions. Briefly, entire hippocampus and frontal cortex samples were weighed and homogenized in a 10-fold volume of lysis buffer. The homogenate was centrifugated at 14,000 × g for 30 min at 4 ◦ C, and the supernates were collected and stored at −80 ◦ C until assay. All samples and standards were applied in duplicate into 96-well immunoplates precoated with rabbit anti-human BDNF antibodies, which were incubated overnight on a shaker at 4 ◦ C. After washing four times, biotinylated mouse anti-BDNF antibodies were added and the immunoplates were incubated for 3 h at room temperature. After washing, streptavidin–HRP conjugate solution was added and the immunoplates were incubated at room temperature for 1 h. TMB/E substrate was added and the immunoplates were incubated at room temperature for 15 min. The plates were immediately read using a microplate reader at 450 nm. The detection limit of the assay was ∼7.8 pg/ml. Data were expressed as mean ± SEMs. Multiple group comparisons were performed using one-way analysis of variance (ANOVA) followed by Dunnett’s test in order to detect inter-group differences. A difference was considered statistically significant when p value was less than 0.05. The serum CORT levels in different groups are given in Table 1. One-way ANOVA showed a significant different on the serum CORT levels among groups (F (3, 20) = 13.29, p < 0.01). The CORT injections resulted in a significant increase in the level of serum CORT in the animals (p < 0.01) compared with the controls. Treatment with TGP and fluoxetine significantly decreased serum CORT levels in the CORT-treated rats (p < 0.01 and p < 0.05, respectively) compared with the CORT-treated rats. The effect of TGP on the percentage of sucrose consumption in CORT-treated rats is given in Fig. 1. One-way ANOVA showed a significant different on the percentage of sucrose consumption among
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Fig. 1. Effect of TGP on the percentage of sucrose consumption in CORT-treated rats. The rats were administered with CORT (40 mg/kg, s.c.) once daily for 21 days, and TGP (160 mg/kg, p.o.) and fluoxetine (20 mg/kg, p.o.) were given to the animals 30 min prior to the CORT injection. Sucrose consumption is the relative volume of sucrose intake when compare with the total liquid intake. Values are given as mean ± SEM (n = 7). # p < 0.01 compared with the control group; ** p < 0.01 compared with the CORT group.
groups (F (3, 24) = 8.41, p < 0.01). The CORT injections resulted in a significant reduction in the percentage of sucrose consumption in the animals (p < 0.01) compared with the controls. Treatment with TGP and fluoxetine significantly increased the percentage of sucrose consumption in the CORT-treated rats (p < 0.01 and p < 0.01, respectively) compared with the CORT-treated rats. The effect of TGP on the immobility time of CORT-treated rats in the forced swim test is given in Fig. 2. One-way ANOVA showed a significant different on the immobility time among groups (F (3, 24) = 7.35, p < 0.01). The CORT injections resulted in a significant reduction in the percentage of sucrose consumption in the animals (p < 0.01) compared with the controls. Treatment with TGP and fluoxetine significantly increased the percentage of sucrose consumption in the CORT-treated rats (p < 0.01 and p < 0.01, respectively) compared with the CORT-treated rats. The effect of TGP on BDNF protein levels in the hippocampus and frontal cortex of CORT-treated rats are given in Fig. 3. One-way ANOVA showed a significant different on BDNF protein levels in both the hippocampus and frontal cortex among groups (F (3, 20) = 8.39, p < 0.01, and F (3, 20) = 4.94, p < 0.05, respectively). Exposure to CORT significantly decreased BDNF protein levels in the hippocampus (p < 0.01) and frontal cortex of rats (p < 0.01) compared with the controls. Treatment with TGP and fluoxetine significantly increased BDNF protein levels in both the hippocampus (p < 0.01 and p < 0.01, respectively) and the frontal cortex (p < 0.05 and p < 0.05, respectively) of CORT-treated rats compared with the CORT-treated rats.
Fig. 2. Effect of TGP on the immobility time of CORT-treated rats in the forced swim test. The rats were administered with CORT (40 mg/kg, s.c.) once daily for 21 days, and TGP (160 mg/kg, p.o.) and fluoxetine (20 mg/kg, p.o.) were given to the animals 30 min prior to the CORT injection. Values are given as mean ± SEM (n = 7). # p < 0.01 compared with the control group; ** p < 0.01 compared with the CORT group.
Fig. 3. Effect of TGP on brain-derived neurotrophic factor (BDNF) protein levels in the hippocampus (A) and frontal cortex (B) of CORT-treated rats. The rats were administered with CORT (40 mg/kg, s.c.) once daily for 21 days, and TGP (160 mg/kg, p.o.) and fluoxetine (20 mg/kg, p.o.) were given to the animals 30 min prior to the CORT injection. Values are given as mean ± SEM (n = 6). # p < 0.01 compared with the control group; * p < 0.05, ** p < 0.01 compared with the CORT group.
In the present study, we investigated, for the first time to our knowledge, the antidepressant-effects of TGP on rats exposed to CORT, using the sucrose preference and forced swim tests to assess their behavior, and measuring BDNF protein levels in the hippocampus and frontal cortex. The results demonstrated that TGP treatment not only had a potent antidepressant-like effect on the CORT-induced depression model in rats but also attenuated the decrease of BDNF protein levels in the hippocampus and frontal cortex of CORT-exposed rats. The sucrose preference test is an indicator of anhedonia-like behavioral change. Anhedonia, a core symptom of major depression among humans, is modeled by inducing a decrease in responsiveness to rewards, as reflected by the reduced consumption of and/or preference for sweetened solutions [34]. In the present study, our data are in line with other findings showing that Repeated CORT injections results in significant decreased in the percentage of sucrose consumption of rats [9,12]. Furthermore, our previous studies have shown that treatment with TGP at doses of 80–160 mg/kg significantly increased the percentage of sucrose consumption in chronic stress-induced depression models in mice and rats [23,24]. The present results consistently show that treatment with TGP at 160 mg/kg significantly suppressed the percentage of CORT injection-induced decrease in sucrose consumption by the rats. The forced swim test has been widely used for assessing the effectiveness of candidate antidepressants. Consistent with previous findings [15,18], in this study, the 3-week CORT injections dramatically increased the immobility time of the rats in the forced swim test, indicating behavioral despair in these animals. Treatment with TGP significantly reversed the CORT-induced increase in the immobility time in rats. Taken together, the results obtained from the behavioral studies indicate that TGP treatment produced an antidepressant-like action in the CORT-treated rats. BDNF is one of the most prevalent neurotrophic factors in the central nervous system. The role of BDNF in the pathogenesis of
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depression and in the mechanism of action of antidepressants is well appreciated. Postmortem analyses have revealed lower levels of BDNF in patients with major depression [5], whereas BDNF infusion into the brain has been found to produce antidepressantlike action [29]. Clinical studies have found decreased BDNF levels in the blood of depressive patients [1,2], whereas antidepressant treatment seems able to normalize the BDNF levels [3]. In the rodent depression model, BDNF expression has been shown to be decreased in the brains of animals, which could be reversed by long-term antidepressant treatment [14,19,31,37]. IbarguenVargas et al. [13] also demonstrated that BDNF deficits can dampen the effects of antidepressants in mice exposed to chronic unpredictable mild stress. Furthermore, BDNF might play an important role in CORTinduced depression [7]. Several studies have reported that treatment with exogenous corticosterone causes a significant decrease in BDNF expression in the hippocampus and frontal cortex [7,16,27,28], which are the brain regions critically involved in the regulation of emotion, motivation, learning, and memory. In vitro studies also showed that CORT treatment significantly decreased BDNF expression in the primary culture of hippocampal neurons [19,38]. Consistent with these findings, in the present study, the 3week CORT injections significantly decreased BDNF protein levels in the hippocampus and frontal cortex of the rats, whereas TGP treatment reversed the CORT-induced changes in BDNF expression. Moreover, our previous studies [23,24] have demonstrated that treatment with TGP significantly increased BDNF protein and mRAN levels in the hippocampus and frontal cortex of both chronic stress-treated and non-stressed rodents, further indicating that BDNF may be involved in the antidepressant-like effect of TGP. In conclusion, the current study demonstrates TGP produces an antidepressant-like effect in CORT-treated rats, which is possibly mediated by increasing BDNF expression in the hippocampus and frontal cortex.
Acknowledgment This study was supported by a Direct Grant for Research from the Chinese University of Hong Kong.
References [1] Aydemir C, Yalcin ES, Aksaray S, Kisa C, Yildirim SG, Uzbay T, et al. Brain-derived neurotrophic factor (BDNF) changes in the serum of depressed women. Prog Neuropsychopharmacol Biol Psychiatry 2006;30:1256–60. [2] Aydemir O, Deveci A, Taskin OE, Taneli F, Esen-Danaci A. Serum brainderived neurotrophic factor level in dysthymia: a comparative study with major depressive disorder. Prog Neuropsychopharmacol Biol Psychiatry 2007;31:1023–6. [3] Bas¸terzi AD, Yazici K, Aslan E, Delialio˘glu N, Tas¸delen B, Acar ST, et al. Effects of fluoxetine and venlafaxine on serum brain derived neurotrophic factor levels in depressed patients. Prog Neuropsychopharmacol Biol Psychiatry 2009;33:281–5. [4] Casarotto PC, Andreatini R. Repeated paroxetine treatment reverses anhedonia induced in rats by chronic mild stress or dexamethasone. Eur Neuropsychopharmacol 2007;17:735–42. [5] Castrén E, Võikar V, Rantamäki T. Role of neurotrophic factors in depression. Curr Opin Pharmacol 2007;7:18–21. [6] Crupi R, Mazzon E, Marino A, La Spada G, Bramanti P, Cuzzocrea S, et al. Melatonin treatment mimics the antidepressant action in chronic corticosterone-treated mice. J Pineal Res 2010;49:123–9. [7] Dwivedi Y, Rizavi HS, Pandey GN. Antidepressants reverse corticosteronemediated decrease in brain-derived neurotrophic factor expression: differential regulation of specific exons by antidepressants and corticosterone. Neuroscience 2006;139:1017–29. [8] Farley S, Apazoglou K, Witkin JM, Giros B, Tzavara ET. Antidepressant-like effects of an AMPA receptor potentiator under a chronic mild stress paradigm. Int J Neuropsychopharmacol 2010;13:1207–18. [9] Gourley SL, Wu FJ, Taylor JR. Corticosterone regulates pERK1/2 map kinase in a chronic depression model. Ann N Y Acad Sci 2008;1148:509–14.
[10] Gregus A, Wintink AJ, Davis AC, Kalynchuk LE. Effect of repeated corticosterone injections and restraint stress on anxiety and depression-like behavior in male rats. Behav Brain Res 2005;156:105–14. [11] Hill MN, Brotto LA, Lee TT, Gorzalka BB. Corticosterone attenuates the antidepressant-like effects elicited by melatonin in the forced swim test in both male and female rats. Prog Neuropsychopharmacol Biol Psychiatry 2003;27:905–11. [12] Huang Z, Zhong XM, Li ZY, Feng CR, Pan AJ, Mao QQ. Curcumin reverses corticosterone-induced depressive-like behavior and decrease in brain BDNF levels in rats. Neurosci Lett 2011;493:145–8. [13] Huston JP, Schulz D, Topic B. Toward an animal model of extinctioninduced despair: focus on aging and physiological indices. J Neural Transm 2009;116:1029–36. [14] Ibarguen-Vargas Y, Surget A, Vourc’h P, Leman S, Andres CR, Gardier AM, et al. Deficit in BDNF does not increase vulnerability to stress but dampens antidepressant-like effects in the unpredictable chronic mild stress. Behav Brain Res 2009;202:245–51. [15] Iijima M, Ito A, Kurosu S, Chaki S. Pharmacological characterization of repeated corticosterone injection-induced depression model in rats. Brain Res 2010;1359:75–80. [16] Jacobsen JP, Mørk A. Chronic corticosterone decreases brain-derived neurotrophic factor (BDNF) mRNA and protein in the hippocampus, but not in the frontal cortex of the rat. Brain Res 2006;1110:221–5. [17] Johnson SA, Fournier NM, Kalynchuk LE. Effect of different doses of corticosterone on depression-like behavior and HPA axis responses to a novel stressor. Behav Brain Res 2006;2:280–8. [18] Lee B, Shim I, Lee HJ, Yang Y, Hahm.H. Effects of acupuncture on chronic corticosterone-induced depression-like behavior and expression of neuropeptide Y in the rats. Neurosci Lett 2009;453:151–6. [19] Li S, Wang C, Wang M, Li W, Matsumoto K, Tang Y. Antidepressant like effects of piperine in chronic mild stress treated mice and its possible mechanisms. Life Sci 2007;15:1373–81. [20] Mao QQ, Huang Z, Ip SP, Che CT. Antidepressant-like effect of ethanol extract from Paeonia lactiflora in mice. Phytother Res 2008;22:1496–9. [21] Mao QQ, Tsai SH, Ip SP, Che CT. Antidepressant-like effects of peony glycosides in mice. J Ethnopharmacol 2008;119:272–5. [22] Mao QQ, Ip SP, Ko KM, Tsai SH, Xian YF, Che CT. Effects of peony glycosides on mice exposed to chronic unpredictable stress: further evidence for antidepressant-like activity. J Ethnopharmacol 2009;124:316–20. [23] Mao QQ, Ip SP, Ko KM, Tsai SH, Che CT. Peony glycosides produce antidepressant-like action in mice exposed to chronic unpredictable mild stress: effects on hypothalamic-pituitary-adrenal function and brainderived neurotrophic factor. Prog Neuropsychopharmacol Biol Psychiatry 2009;33:1211–6. [24] Mao QQ, Xian YF, Ip SP, Tsai SH, Che CT. Long-term treatment with peony glycosides reverses chronic unpredictable mild stress-induced depressive-like behavior via increasing expression of neurotrophins in rat brain. Behav Brain Res 2010;210:171–7. [25] Murray F, Smith DW, Hutson PH. Chronic low dose corticosterone exposure decreased hippocampal cell proliferation, volume and induced anxiety and depression like behaviours in mice. Eur J Pharmacol 2008;583: 115–27. [26] Porsolt RD, Pichon MLE, Jalfre M. Behavioral despair in mice: a primary screening test for antidepressant. Arch Int Pharmacodyn Ther 1997;229:327–36. [27] Schaaf MJ, Hoetelmans RWM, de Kloet ER, Vreugdenhil E. Corticosterone regulates expression of BDNF and trkB but not NT-3 and trkC mRNA in the rat hippocampus. J Neurosci Res 1997;48:334–41. [28] Schaaf MJ, de Jong J, de Kloet ER, Vreugdenhil E. Downregulation of BDNF mRNA and protein in the rat hippocampus by corticosterone. Brain Res 1998;813:112–20. [29] Siuciak JA, Lewis DR, Wiegand SJ, Lindsay RM. Antidepressant-like effect of brain-derived neurotrophic factor (BDNF). Pharmacol Biochem Behav 1997;56:131–7. [30] Surget A, Tanti A, Leonardo ED, Laugeray A, Rainer Q, Touma C, et al. Antidepressants recruit new neurons to improve stress response regulation. Mol Psychiatry 2011, in press, doi:10.1038/mp.2011.48. [31] Topic B, Huston JP, Namestkova K, Zhu SW, Mohammed AH, Schulz D, et al. despair in aged and adult rats: links to neurotrophins in frontal cortex and hippocampus. Neurobiol Learn Mem 2008;90:519–26. [32] Wang H, Wei W, Wang NP, Wu CY, Yan SX, Yue L, et al. Effects of total glucosides of peony on immunological hepatic fibrosis in rats. World J Gastroenterol 2005;14:2124–9. [33] Watson S, Mackin P. HPA axis function in mood disorders. Psychiatry 2007;5:166–70. [34] Willner P. Chronic mild stress (CMS) revisited: consistency and behaviouralneurobiological concordance in the effects of CMS. Neuropsychobiology 2005;52:90–110. [35] Wu Y, Ren K, Liang C, Yuan L, Qi X, Dong J, et al. Renoprotective effect of total glucosides of paeony (TGP) and its mechanism in experimental diabetes. J Pharmacol Sci 2009;109:78–87. [36] Xu HM, Wei W, Jia XY, Chang Y, Zhang L. Effects and mechanisms of total glucosides of peony on adjuvant arthritis in rats. J Ethnopharmacol 2007;109: 442–8. [37] Xu Y, Ku B, Tie L, Yao H, Jiang W, Ma X, et al. Curcumin reverses the effects of chronic stress on behavior, the HPA axis, BDNF expression and phosphorylation of CREB. Brain Res 2006;1122:56–64.
Q.-Q. Mao et al. / Behavioural Brain Research 227 (2012) 305–309 [38] Yu IT, Lee SH, Lee YS, Son H. Differential effects of corticosterone and dexamethasone on hippocampal neurogenesis in vitro. Biochem Biophys Res Commun 2004;317:484–90. [39] Zhang P, Zhang JJ, Su J, Qi XM, Wu YG, Shen JJ. Effect of total glucosides of paeony on the expression of nephrin in the kidneys from diabetic rats. Am J Chin Med 2009;37:295–307.
309
[40] Zhao Y, Ma R, Shen J, Su H, Xing D, Du L. A mouse model of depression induced by repeated corticosterone injections. Eur J Pharmacol 2008;581: 113–20. [41] Zheng YQ, Wei W. Total glucosides of paeony suppresses adjuvant arthritis in rats and intervenes cytokine-signaling between different types of synoviocytes. Int Immunopharmacol 2005;5:1560–73.
Contents lists available at SciVerse ScienceDirect
Behavioural Brain Research journal homepage: www.elsevier.com/locate/bbr
Short communication
Peony glycosides reverse the effects of corticosterone on behavior and brain BDNF expression in rats Qing-Qiu Mao a , Zhen Huang b , Siu-Po Ip a,∗ , Yan-Fang Xian a , Chun-Tao Che c a b c
School of Chinese Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong College of Pharmacy, Zhejiang Chinese Medicine University, Hangzhou, 310053 Zhejiang, China Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, IL 60612, USA
a r t i c l e
i n f o
Article history: Received 9 October 2011 Received in revised form 8 November 2011 Accepted 12 November 2011 Available online 19 November 2011 Keywords: Antidepressant Brain-derived neurotrophic factor Corticosterone Peony glycosides Rat
a b s t r a c t Repeated injections of corticosterone (CORT) induce the dysregulation of the hypothalamic-pituitaryadrenal (HPA) axis, resulting in depressive-like behavior. This study aimed to examine the antidepressantlike effect and the possible mechanisms of total glycosides of peony (TGP) in the CORT-induced depression model in rats. The results showed that the 3-week CORT injections induced the significant increase in serum CORT levels in rats. Repeated CORT injections also caused depression-like behavior in rats, as indicated by the significant decrease in sucrose consumption and increase in immobility time in the forced swim test. Moreover, it was found that brain-derived neurotrophic factor (BDNF) protein levels in the hippocampus and frontal cortex were significantly decreased in CORT-treated rats. Treatment of the rats with TGP significantly suppressed the depression-like behavior and increased brain BDNF levels in CORT-treated rats. The results suggest that TGP produces an antidepressant-like effect in CORT-treated rats, which is possibly mediated by increasing BDNF expression in the hippocampus and frontal cortex. © 2011 Elsevier B.V. All rights reserved.
Depression is a commonly occurring, debilitating, and lifethreatening psychiatric disorder. Based on latest available data from the World Health Organization, depression is expected to become the second leading cause of disease-related disability by the year 2020. Although the monoamine theory of depression has been extensively investigated, it is unable to fully explain the pathophysiology of depression [33]. In recent years, a substantial amount of experimental and clinical data has supported the notion that dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is involved in the pathogenesis of depression [33]. The HPA axis is activated in response to stress, which results in increased concentrations of glucocorticoids in the circulating blood. Under normal conditions, blood glucocorticoid level is tightly regulated by a negative feedback mechanism. However, high concentrations of blood glucocorticoids are reportedly maintained in patients with depression due to a dysfunction in the feedback mechanism [17,33]. More importantly, high levels of glucocorticoids have been demonstrated to induce depressive-like behavior in rodents, as indicated by the significant decrease in sucrose consumption, and increase in immobility time in forced swim tests and tail suspension tests; these changes, however, are significantly reversed by antidepressants and acupuncture treatment [4,6,18]. Treatment with high levels of glucocorticoids have
∗ Corresponding author. Tel.: +852 3163 4457; fax: +852 3163 4459. E-mail address: [email protected] (S.-P. Ip). 0166-4328/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.bbr.2011.11.016
also been found to produce changes in neurochemistry and brain anatomy, all of which may be related to depression [7,17,25]. These findings suggest that a glucocorticoid-induced depression model in rodents is valid for evaluating the efficacy of potential antidepressants and explore the mechanism of action of antidepressants [10,11,15,40]. The root part of Paeonia lactiflora Pall. (Ranunculaceae), commonly known as peony, is a commonly used medicinal herbs in China, Korea and Japan. A recent study in our laboratory has demonstrated the antidepressant effect of peony in the mouse model of behavioral despair [20]. Glycosides, including paeoniflorin and albiflorin, are known to be the biologically active ingredients of peony, and the total glycosides fraction of peony has been shown to possess anti-inflammatory, antioxidant, anti-hepatic fibrosis, antidiabetic and renoprotective properties [32,35,36,39,41]. Studies from our laboratory also showed that the intragastric administration of total glycosides of peony (TGP) caused a significant reduction of immobility time in both forced swim and tail suspension tests in mice [21]. The antidepressive effect of TGP was also observed in mice and rats exposed to chronic unpredictable stress, which were related to the modulation of the hypothalamicpituitary-adrenal axis function, the inhibition of oxidative stress, and the up-regulation of neurotrophins expression [22–24]. However, there is no information about the antidepressant-like effect of TGP in the glucocorticoid-induced depression model. Therefore, in this study, the antidepressant-like effect of TGP treatment was further evaluated in a rat model of depression induced by
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corticosterone (CORT), a principal glucocorticoid. Given that BDNF is involved in the molecular pathophysiology of depression and upregulation of its expression may contribute to the action of antidepressants [13,14,19,31,37], we also investigated whether the antidepressant-like effect of TGP in CORT-treated rats was related to the upregulation of BDNF expression by measuring BDNF protein levels in brain tissues. Male Sprague-Dawley rats weighing 200–220 g were obtained from the Laboratory Animal Services Center, The Chinese University of Hong Kong, Hong Kong. The animals were maintained on a 12-h light/dark cycle under controlled temperature conditions (22 ± 2 ◦ C) and given standard food and water ad libitum. The rats were allowed to acclimatize for 3 days before the experiments. The animal experiments have been approved by the Animal Experimentation Ethics Committee of the Chinese University of Hong Kong, and they conform to the guidelines of the “Principles of Laboratory Animal Care” (NIH publication No.80-23, revised 1996). Efforts were made to minimize the number and suffering of the animals. TGP (light yellow brown powder) was supplied by Ningbo Liwah Pharmaceutical Co., Ltd. (Zhejiang, China). TGP has been characterized by high-performance liquid chromatography in our previous studies [21–24] which mainly contains paeoniflorin and albiflorin. A voucher sample (TGP071024) was deposited in the School of Chinese Medicine for future reference. CORT and fluoxetine (a selective serotonin reuptake inhibitor, used as positive control) were purchased from Sigma–Aldrich (St Louis, MO, USA). The rats were divided into four groups of seven animals in each: vehicle control group, CORT plus vehicle group, CORT plus TGP (160 mg/kg) group and CORT plus fluoxetine (20 mg/kg) group. CORT (40 mg/kg, dissolved in saline containing 0.1% dimethyl sulfoxide and 0.1% Tween-80) was administrated subcutaneously (s.c.) in a volume of 5 ml/kg once daily for 21 days. TGP and fluoxetine were administered intragastrically (p.o.) in a volume of 10 ml/kg 30 min prior to the CORT injection for 21 days. The doses of TGP [24] and fluoxetine [8,30] were chosen based on our previous study and previously published reports. The sucrose preference test was carried out 24 h after the last drug treatment. The test was performed as described previously [24], with minor modifications. Before the test, the rats were trained to adapt to sucrose solution (1%, w/v) by placing two bottles of sucrose solution in each cage for 24 h; then one of the bottles was replaced with water for 24 h. After the adaptation procedure, the rats were deprived of water and food for 24 h. The sucrose preference test was conducted at 9:00 a.m. The rats were housed in individual cages and given free access to the two bottles containing 100 ml of sucrose solution (1%, w/v) and 100 ml of water, respectively. After 3 h, the volumes of consumed sucrose solution and water were recorded and the sucrose preference was calculated by the following formula: sucrose consumption Sucrose preference = water consumption+sucrose × consumption 100. The forced swim test was carried out 48 h after the sucrose preference test. The test was performed according to the method by Porsolt et al. [26] with minor modifications. As a pre-test, the rats were individually forced to swim for 15 min in a vertical plastic cylinder (diameter 21 cm, height 50 cm) containing 25 cm of water, maintained at 25 ± 1 ◦ C. The rats were then removed and dried before being returned to cages. After 24 h, the rats were again placed in the cylinders in the same system depicted above. The total duration of immobility (s) was quantified during a test period of 5 min by two observers who were blind to the treatment given to each rat. A rat was considered immobile whenever it remained floating passively in a slightly hunched but upright position with its head just above the surface.
Table 1 Serum CORT levels in different groups. Treatment
CORT level (ng/ml)
Control CORT + vehicle CORT + TGP CORT + fluoxetine
49.0 120.5 69.7 88.3
± ± ± ±
3.5 10.7# 9.7** 7.5*
Values given are the mean ± SEMs (n = 6). # p < 0.01 compared with the control group. * p < 0.05 compared with the CORT group. ** p < 0.01 compared with the CORT group.
Twenty-four hours after the forced swim test, the rats were sacrificed by decapitation and the blood samples were collected in tubes. Serum was separated by centrifugation at 4000 × g for 10 min and stored at −80 ◦ C until assay. Whole brains were rapidly removed from rats and chilled in an ice-cold saline solution. Various brain areas, including the hippocampus and frontal cortex, were dissected on a cold plate, and immediately frozen in liquid nitrogen. The tissue samples were stored at −80 ◦ C until assay. Serum corticosterone level was measured using a commercially available enzyme-linked immunosorbent assay (ELISA) kit (Assay Designs, Inc., Michigan) according to the manufacturer’s protocol. Briefly, samples, corticosterone standard, corticosterone EIA conjugate and corticosterone EIA antibody were applied into a 96-well plate precoated with donkey anti-Sheep IgG and incubated on a shaker for 2 h at room temperature. Then pNpp substrate solution was added and incubated at room temperature for 1 h after three washes. The reaction was stopped with trisodium phosphate and absorbance was recorded at 405 nm immediately. The detection limit of the assay is ∼27 pg/ml. The BDNF content in the hippocampus and frontal cortex was measured using a commercially available enzyme-linked immunosorbent assay kit (Chemicon International, Temecula, CA) according to the manufacturer’s instructions. Briefly, entire hippocampus and frontal cortex samples were weighed and homogenized in a 10-fold volume of lysis buffer. The homogenate was centrifugated at 14,000 × g for 30 min at 4 ◦ C, and the supernates were collected and stored at −80 ◦ C until assay. All samples and standards were applied in duplicate into 96-well immunoplates precoated with rabbit anti-human BDNF antibodies, which were incubated overnight on a shaker at 4 ◦ C. After washing four times, biotinylated mouse anti-BDNF antibodies were added and the immunoplates were incubated for 3 h at room temperature. After washing, streptavidin–HRP conjugate solution was added and the immunoplates were incubated at room temperature for 1 h. TMB/E substrate was added and the immunoplates were incubated at room temperature for 15 min. The plates were immediately read using a microplate reader at 450 nm. The detection limit of the assay was ∼7.8 pg/ml. Data were expressed as mean ± SEMs. Multiple group comparisons were performed using one-way analysis of variance (ANOVA) followed by Dunnett’s test in order to detect inter-group differences. A difference was considered statistically significant when p value was less than 0.05. The serum CORT levels in different groups are given in Table 1. One-way ANOVA showed a significant different on the serum CORT levels among groups (F (3, 20) = 13.29, p < 0.01). The CORT injections resulted in a significant increase in the level of serum CORT in the animals (p < 0.01) compared with the controls. Treatment with TGP and fluoxetine significantly decreased serum CORT levels in the CORT-treated rats (p < 0.01 and p < 0.05, respectively) compared with the CORT-treated rats. The effect of TGP on the percentage of sucrose consumption in CORT-treated rats is given in Fig. 1. One-way ANOVA showed a significant different on the percentage of sucrose consumption among
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Fig. 1. Effect of TGP on the percentage of sucrose consumption in CORT-treated rats. The rats were administered with CORT (40 mg/kg, s.c.) once daily for 21 days, and TGP (160 mg/kg, p.o.) and fluoxetine (20 mg/kg, p.o.) were given to the animals 30 min prior to the CORT injection. Sucrose consumption is the relative volume of sucrose intake when compare with the total liquid intake. Values are given as mean ± SEM (n = 7). # p < 0.01 compared with the control group; ** p < 0.01 compared with the CORT group.
groups (F (3, 24) = 8.41, p < 0.01). The CORT injections resulted in a significant reduction in the percentage of sucrose consumption in the animals (p < 0.01) compared with the controls. Treatment with TGP and fluoxetine significantly increased the percentage of sucrose consumption in the CORT-treated rats (p < 0.01 and p < 0.01, respectively) compared with the CORT-treated rats. The effect of TGP on the immobility time of CORT-treated rats in the forced swim test is given in Fig. 2. One-way ANOVA showed a significant different on the immobility time among groups (F (3, 24) = 7.35, p < 0.01). The CORT injections resulted in a significant reduction in the percentage of sucrose consumption in the animals (p < 0.01) compared with the controls. Treatment with TGP and fluoxetine significantly increased the percentage of sucrose consumption in the CORT-treated rats (p < 0.01 and p < 0.01, respectively) compared with the CORT-treated rats. The effect of TGP on BDNF protein levels in the hippocampus and frontal cortex of CORT-treated rats are given in Fig. 3. One-way ANOVA showed a significant different on BDNF protein levels in both the hippocampus and frontal cortex among groups (F (3, 20) = 8.39, p < 0.01, and F (3, 20) = 4.94, p < 0.05, respectively). Exposure to CORT significantly decreased BDNF protein levels in the hippocampus (p < 0.01) and frontal cortex of rats (p < 0.01) compared with the controls. Treatment with TGP and fluoxetine significantly increased BDNF protein levels in both the hippocampus (p < 0.01 and p < 0.01, respectively) and the frontal cortex (p < 0.05 and p < 0.05, respectively) of CORT-treated rats compared with the CORT-treated rats.
Fig. 2. Effect of TGP on the immobility time of CORT-treated rats in the forced swim test. The rats were administered with CORT (40 mg/kg, s.c.) once daily for 21 days, and TGP (160 mg/kg, p.o.) and fluoxetine (20 mg/kg, p.o.) were given to the animals 30 min prior to the CORT injection. Values are given as mean ± SEM (n = 7). # p < 0.01 compared with the control group; ** p < 0.01 compared with the CORT group.
Fig. 3. Effect of TGP on brain-derived neurotrophic factor (BDNF) protein levels in the hippocampus (A) and frontal cortex (B) of CORT-treated rats. The rats were administered with CORT (40 mg/kg, s.c.) once daily for 21 days, and TGP (160 mg/kg, p.o.) and fluoxetine (20 mg/kg, p.o.) were given to the animals 30 min prior to the CORT injection. Values are given as mean ± SEM (n = 6). # p < 0.01 compared with the control group; * p < 0.05, ** p < 0.01 compared with the CORT group.
In the present study, we investigated, for the first time to our knowledge, the antidepressant-effects of TGP on rats exposed to CORT, using the sucrose preference and forced swim tests to assess their behavior, and measuring BDNF protein levels in the hippocampus and frontal cortex. The results demonstrated that TGP treatment not only had a potent antidepressant-like effect on the CORT-induced depression model in rats but also attenuated the decrease of BDNF protein levels in the hippocampus and frontal cortex of CORT-exposed rats. The sucrose preference test is an indicator of anhedonia-like behavioral change. Anhedonia, a core symptom of major depression among humans, is modeled by inducing a decrease in responsiveness to rewards, as reflected by the reduced consumption of and/or preference for sweetened solutions [34]. In the present study, our data are in line with other findings showing that Repeated CORT injections results in significant decreased in the percentage of sucrose consumption of rats [9,12]. Furthermore, our previous studies have shown that treatment with TGP at doses of 80–160 mg/kg significantly increased the percentage of sucrose consumption in chronic stress-induced depression models in mice and rats [23,24]. The present results consistently show that treatment with TGP at 160 mg/kg significantly suppressed the percentage of CORT injection-induced decrease in sucrose consumption by the rats. The forced swim test has been widely used for assessing the effectiveness of candidate antidepressants. Consistent with previous findings [15,18], in this study, the 3-week CORT injections dramatically increased the immobility time of the rats in the forced swim test, indicating behavioral despair in these animals. Treatment with TGP significantly reversed the CORT-induced increase in the immobility time in rats. Taken together, the results obtained from the behavioral studies indicate that TGP treatment produced an antidepressant-like action in the CORT-treated rats. BDNF is one of the most prevalent neurotrophic factors in the central nervous system. The role of BDNF in the pathogenesis of
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depression and in the mechanism of action of antidepressants is well appreciated. Postmortem analyses have revealed lower levels of BDNF in patients with major depression [5], whereas BDNF infusion into the brain has been found to produce antidepressantlike action [29]. Clinical studies have found decreased BDNF levels in the blood of depressive patients [1,2], whereas antidepressant treatment seems able to normalize the BDNF levels [3]. In the rodent depression model, BDNF expression has been shown to be decreased in the brains of animals, which could be reversed by long-term antidepressant treatment [14,19,31,37]. IbarguenVargas et al. [13] also demonstrated that BDNF deficits can dampen the effects of antidepressants in mice exposed to chronic unpredictable mild stress. Furthermore, BDNF might play an important role in CORTinduced depression [7]. Several studies have reported that treatment with exogenous corticosterone causes a significant decrease in BDNF expression in the hippocampus and frontal cortex [7,16,27,28], which are the brain regions critically involved in the regulation of emotion, motivation, learning, and memory. In vitro studies also showed that CORT treatment significantly decreased BDNF expression in the primary culture of hippocampal neurons [19,38]. Consistent with these findings, in the present study, the 3week CORT injections significantly decreased BDNF protein levels in the hippocampus and frontal cortex of the rats, whereas TGP treatment reversed the CORT-induced changes in BDNF expression. Moreover, our previous studies [23,24] have demonstrated that treatment with TGP significantly increased BDNF protein and mRAN levels in the hippocampus and frontal cortex of both chronic stress-treated and non-stressed rodents, further indicating that BDNF may be involved in the antidepressant-like effect of TGP. In conclusion, the current study demonstrates TGP produces an antidepressant-like effect in CORT-treated rats, which is possibly mediated by increasing BDNF expression in the hippocampus and frontal cortex.
Acknowledgment This study was supported by a Direct Grant for Research from the Chinese University of Hong Kong.
References [1] Aydemir C, Yalcin ES, Aksaray S, Kisa C, Yildirim SG, Uzbay T, et al. Brain-derived neurotrophic factor (BDNF) changes in the serum of depressed women. Prog Neuropsychopharmacol Biol Psychiatry 2006;30:1256–60. [2] Aydemir O, Deveci A, Taskin OE, Taneli F, Esen-Danaci A. Serum brainderived neurotrophic factor level in dysthymia: a comparative study with major depressive disorder. Prog Neuropsychopharmacol Biol Psychiatry 2007;31:1023–6. [3] Bas¸terzi AD, Yazici K, Aslan E, Delialio˘glu N, Tas¸delen B, Acar ST, et al. Effects of fluoxetine and venlafaxine on serum brain derived neurotrophic factor levels in depressed patients. Prog Neuropsychopharmacol Biol Psychiatry 2009;33:281–5. [4] Casarotto PC, Andreatini R. Repeated paroxetine treatment reverses anhedonia induced in rats by chronic mild stress or dexamethasone. Eur Neuropsychopharmacol 2007;17:735–42. [5] Castrén E, Võikar V, Rantamäki T. Role of neurotrophic factors in depression. Curr Opin Pharmacol 2007;7:18–21. [6] Crupi R, Mazzon E, Marino A, La Spada G, Bramanti P, Cuzzocrea S, et al. Melatonin treatment mimics the antidepressant action in chronic corticosterone-treated mice. J Pineal Res 2010;49:123–9. [7] Dwivedi Y, Rizavi HS, Pandey GN. Antidepressants reverse corticosteronemediated decrease in brain-derived neurotrophic factor expression: differential regulation of specific exons by antidepressants and corticosterone. Neuroscience 2006;139:1017–29. [8] Farley S, Apazoglou K, Witkin JM, Giros B, Tzavara ET. Antidepressant-like effects of an AMPA receptor potentiator under a chronic mild stress paradigm. Int J Neuropsychopharmacol 2010;13:1207–18. [9] Gourley SL, Wu FJ, Taylor JR. Corticosterone regulates pERK1/2 map kinase in a chronic depression model. Ann N Y Acad Sci 2008;1148:509–14.
[10] Gregus A, Wintink AJ, Davis AC, Kalynchuk LE. Effect of repeated corticosterone injections and restraint stress on anxiety and depression-like behavior in male rats. Behav Brain Res 2005;156:105–14. [11] Hill MN, Brotto LA, Lee TT, Gorzalka BB. Corticosterone attenuates the antidepressant-like effects elicited by melatonin in the forced swim test in both male and female rats. Prog Neuropsychopharmacol Biol Psychiatry 2003;27:905–11. [12] Huang Z, Zhong XM, Li ZY, Feng CR, Pan AJ, Mao QQ. Curcumin reverses corticosterone-induced depressive-like behavior and decrease in brain BDNF levels in rats. Neurosci Lett 2011;493:145–8. [13] Huston JP, Schulz D, Topic B. Toward an animal model of extinctioninduced despair: focus on aging and physiological indices. J Neural Transm 2009;116:1029–36. [14] Ibarguen-Vargas Y, Surget A, Vourc’h P, Leman S, Andres CR, Gardier AM, et al. Deficit in BDNF does not increase vulnerability to stress but dampens antidepressant-like effects in the unpredictable chronic mild stress. Behav Brain Res 2009;202:245–51. [15] Iijima M, Ito A, Kurosu S, Chaki S. Pharmacological characterization of repeated corticosterone injection-induced depression model in rats. Brain Res 2010;1359:75–80. [16] Jacobsen JP, Mørk A. Chronic corticosterone decreases brain-derived neurotrophic factor (BDNF) mRNA and protein in the hippocampus, but not in the frontal cortex of the rat. Brain Res 2006;1110:221–5. [17] Johnson SA, Fournier NM, Kalynchuk LE. Effect of different doses of corticosterone on depression-like behavior and HPA axis responses to a novel stressor. Behav Brain Res 2006;2:280–8. [18] Lee B, Shim I, Lee HJ, Yang Y, Hahm.H. Effects of acupuncture on chronic corticosterone-induced depression-like behavior and expression of neuropeptide Y in the rats. Neurosci Lett 2009;453:151–6. [19] Li S, Wang C, Wang M, Li W, Matsumoto K, Tang Y. Antidepressant like effects of piperine in chronic mild stress treated mice and its possible mechanisms. Life Sci 2007;15:1373–81. [20] Mao QQ, Huang Z, Ip SP, Che CT. Antidepressant-like effect of ethanol extract from Paeonia lactiflora in mice. Phytother Res 2008;22:1496–9. [21] Mao QQ, Tsai SH, Ip SP, Che CT. Antidepressant-like effects of peony glycosides in mice. J Ethnopharmacol 2008;119:272–5. [22] Mao QQ, Ip SP, Ko KM, Tsai SH, Xian YF, Che CT. Effects of peony glycosides on mice exposed to chronic unpredictable stress: further evidence for antidepressant-like activity. J Ethnopharmacol 2009;124:316–20. [23] Mao QQ, Ip SP, Ko KM, Tsai SH, Che CT. Peony glycosides produce antidepressant-like action in mice exposed to chronic unpredictable mild stress: effects on hypothalamic-pituitary-adrenal function and brainderived neurotrophic factor. Prog Neuropsychopharmacol Biol Psychiatry 2009;33:1211–6. [24] Mao QQ, Xian YF, Ip SP, Tsai SH, Che CT. Long-term treatment with peony glycosides reverses chronic unpredictable mild stress-induced depressive-like behavior via increasing expression of neurotrophins in rat brain. Behav Brain Res 2010;210:171–7. [25] Murray F, Smith DW, Hutson PH. Chronic low dose corticosterone exposure decreased hippocampal cell proliferation, volume and induced anxiety and depression like behaviours in mice. Eur J Pharmacol 2008;583: 115–27. [26] Porsolt RD, Pichon MLE, Jalfre M. Behavioral despair in mice: a primary screening test for antidepressant. Arch Int Pharmacodyn Ther 1997;229:327–36. [27] Schaaf MJ, Hoetelmans RWM, de Kloet ER, Vreugdenhil E. Corticosterone regulates expression of BDNF and trkB but not NT-3 and trkC mRNA in the rat hippocampus. J Neurosci Res 1997;48:334–41. [28] Schaaf MJ, de Jong J, de Kloet ER, Vreugdenhil E. Downregulation of BDNF mRNA and protein in the rat hippocampus by corticosterone. Brain Res 1998;813:112–20. [29] Siuciak JA, Lewis DR, Wiegand SJ, Lindsay RM. Antidepressant-like effect of brain-derived neurotrophic factor (BDNF). Pharmacol Biochem Behav 1997;56:131–7. [30] Surget A, Tanti A, Leonardo ED, Laugeray A, Rainer Q, Touma C, et al. Antidepressants recruit new neurons to improve stress response regulation. Mol Psychiatry 2011, in press, doi:10.1038/mp.2011.48. [31] Topic B, Huston JP, Namestkova K, Zhu SW, Mohammed AH, Schulz D, et al. despair in aged and adult rats: links to neurotrophins in frontal cortex and hippocampus. Neurobiol Learn Mem 2008;90:519–26. [32] Wang H, Wei W, Wang NP, Wu CY, Yan SX, Yue L, et al. Effects of total glucosides of peony on immunological hepatic fibrosis in rats. World J Gastroenterol 2005;14:2124–9. [33] Watson S, Mackin P. HPA axis function in mood disorders. Psychiatry 2007;5:166–70. [34] Willner P. Chronic mild stress (CMS) revisited: consistency and behaviouralneurobiological concordance in the effects of CMS. Neuropsychobiology 2005;52:90–110. [35] Wu Y, Ren K, Liang C, Yuan L, Qi X, Dong J, et al. Renoprotective effect of total glucosides of paeony (TGP) and its mechanism in experimental diabetes. J Pharmacol Sci 2009;109:78–87. [36] Xu HM, Wei W, Jia XY, Chang Y, Zhang L. Effects and mechanisms of total glucosides of peony on adjuvant arthritis in rats. J Ethnopharmacol 2007;109: 442–8. [37] Xu Y, Ku B, Tie L, Yao H, Jiang W, Ma X, et al. Curcumin reverses the effects of chronic stress on behavior, the HPA axis, BDNF expression and phosphorylation of CREB. Brain Res 2006;1122:56–64.
Q.-Q. Mao et al. / Behavioural Brain Research 227 (2012) 305–309 [38] Yu IT, Lee SH, Lee YS, Son H. Differential effects of corticosterone and dexamethasone on hippocampal neurogenesis in vitro. Biochem Biophys Res Commun 2004;317:484–90. [39] Zhang P, Zhang JJ, Su J, Qi XM, Wu YG, Shen JJ. Effect of total glucosides of paeony on the expression of nephrin in the kidneys from diabetic rats. Am J Chin Med 2009;37:295–307.
309
[40] Zhao Y, Ma R, Shen J, Su H, Xing D, Du L. A mouse model of depression induced by repeated corticosterone injections. Eur J Pharmacol 2008;581: 113–20. [41] Zheng YQ, Wei W. Total glucosides of paeony suppresses adjuvant arthritis in rats and intervenes cytokine-signaling between different types of synoviocytes. Int Immunopharmacol 2005;5:1560–73.