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Reversal by serotonergic agents of reserpine-induced hyperalgesia in rats
European Journal of Pharmacology, 83 (1982) 325-328
325
Elsevier Biomedical Press
Short communication REVERSAL BY S E R O T O N E R G I C A G E N T S OF R E S E R P I N E - I N D U C E D HYPERALGESIA
IN RATS SHRINIVAS K. KULKARNI and REJIT K. ROBERT
Pharmacology Division, Department of Pharmaceutical Sciences, Panjab University, Chandigarh, India Received 26 July 1982, acccepted 9 August 1982
S.K. KULKARNI and R.K. ROBERT, Reversal by serotonergic agents o/ reserpine-induced hyperalgesia in rats, European J. Pharmacol. 83 (1982) 325-328 Reserpine (4 mg/kg) induced a time-dependent reduction in pain threshold (hyperalgesia) as observed by the tail-flick technique in rats. Serotonin, its precursor 5-hydroxytryptophan or the receptor agonist, quipazine reversed the reserpine-induced hyperalgesia. On the other hand, piribedil, amantadine, imipramine or desipramine treatment failed to reverse the reserpine-induced hyperalgesia. Similarly, intracerebroventricular administration of dopamine or noradrenaline also had no effect on reserpine-induced hyperalgesia. These observations not only suggested a role of serotonin in hyperalgesia but also that reserpine hyperalgesia is suitable for selective study of serotonin-mediated responses in rats. 5-Hydroxytryptophan
Hyperalgesia
Reserpine
Quipazine
1. Introduction
While studying the role of catecholamines in stress analgesia we have found that reserpine produced hyperalgesia in animals (Kulkarni, 1980). Since reserpine depletes brain catecholamines and serotonin, and since brain monoamines are implicated in the regulation of pain perception and stress analgesia (Brodie et al., 1966; Carlsson et al., 1957; Medakovic and Banic, 1964; GarciaSevilla et al., 1978; Kulkarni, 1980), an attempt was made to investigate the mechanism of reserpine-induced hyperalgesia in rats.
2. Materials and methods
2.1. Animals and technique Wistar rats (150-200g) of either sex were used in the present study. The pain threshold to radiant heat was measured using an analgesiometer. Baseline latencies to tail-flick withdrawal from the radiant heat source ( 4 - 6 s ) were established. A 0014-2999/82/0000-0000/$02.75 © 1982 Elsevier Biomedical Press
Serotonin
minimum of 5 (2 min interval) trials were recorded for each animal before the test. Animals were tested at different intervals (l, 2, 4, 8 and 24h) after reserpine. Another group of rats were chronically implanted with polythelene cannulae into the right ventricle for intraventricular (i.c.v.) administration of biogenic amines (Noble et al., 1967). Each group consisted of a minimum of five animals. Statistical analysis was done using Student's t-test. 2.2. Drugs Reserpine (CIBA-Geigy) was administered in a dose of 4 m g / k g intraperitoneally (i.p.). Quipazine (10 mg/kg, Miles Laboratories), imipramine, desipramine (10 mg/kg), amantadine (20 mg/kg, Aldrich Chemicals) or piribedil (20 mg/kg) were administered i.p., 3.5 h after reserpine. 5-Hydroxytryptophan (5-HTP, 75 mg/kg, Sigma) and tranylcypromine (5 mg/kg, SKF, given 15 min before 5-HTP) were also administered 3.5 h after reserpine. The reaction time to radiant heat was also determined in these animals at 4, 8 and 24 h
326
! ....
Control
Re.,°t,,in~ O"~/k~) i
I
I 4
I
I e
Time
I z4
(~hours~after reserpine
Fig. I. Effect of reserpine (4 m g / k g ) on reaction time (s±S.E.M.) of rats to radiant heat as determined by tail-flick technique. Maximum reduction in the pain threshold (hyperalgesia) was observed at 4 h after reserpine. Each group consisted of a minimum of five rats.
ii f
[ ] Control ~/J Reserpine
,~. t= ~,.
[ ] Re,Lerpine+Drug
~
1~o
Control Tranyl cypromine
Ouipozine Amantodine~
pmmine Imiprom nePiribedil
+ 5-HTP Fig. 2. Histograms (s-S.E.M.) showing the reversal of reserpine ([])-induced hypcralgesia by various drug (B) treatments. 5-I-lydroxytr3,ptophan (5-HTP, 75 mg/kg)+ tranylcyprornine (5 mg/kg), quipazine (10 mg/kg), amantadine (20 mg/kg), imipramine (10 mg/kg), desipramine (10 mg/kg) and piril~lil (20 mg/kg) were administered i.p. 3.5 h after reserpine (4 mg/kg). Each group consisted of a minimum of five anima|s. * P<0.001 as compared to reserpine treatment.
327
after reserpine. The observations after 4 h of reserpine were used for statistical analysis as hyperalgesia was maximal at this time interval. Noradrenaline (10 /~g, Sigma), dopamine (60 /~g, Orient Pharma) and 5-hydroxytryptamine (20 p.g, Sigma) were administered i.c.v, in 20/~l saline with the help of a Hamilton microsyringe 3.5 h after reserpine. These doses were selected on the basis of earlier work in this laboratory.
3. Results
Reserpine produced a time-dependent reduction in pain threshold to radiant heat i.e. the reaction time was reduced. The maximum hyperalgesic effect was observed 4 h after reserpine and the animals recovered within 24 h following reserpine (fig. 1). Sedation, ptosis and diarrhoea were also seen in animals treated with reserpine. Quipazine did not show any effect of its own on the pain reaction in control animals but it significantly reversed the reserpine-induced hyperalgesia. On the other hand, 5-HTP and tranylcypromine given together showed an analgesic effect and also reversed the response reserpine. The animals were hyperactive and exhibited body tremors following this treatment. The effect lasted upto 24h and mortality (2/5) was observed in this group (fig. 2). Intraventricular administration of noradrenaline (t -~ 1.3) and dopamine (t = 0.2) did not have any effect while 5-hydroxytryptamine significantly (t = 3.7, P < 0.001) reversed the reserpine hyperalgesia. In contrast to serotonergic agents, dopamine agonists like piribedil or amantadine failed to reverse the reserpine-induced hyperalgesia. Similarly, tricylic antidepressants like imipramine or desipramine failed to reverse the response to reserpine though these agents antagonized the reserpine-induced sedation in rats (fig. 2).
cursors of catecholamine and serotonin reverse not only the behavioural effects but also the biochemical changes caused by reserpine (Carlsson et al., 1957). Certain antidepressant drugs are also reported to reverse both behavioural and cardiovascular effects of reserpine (Domenjoz and Theobold, 1959; Costa et al., 1960). Recently it has been reported that reserpine induced hyperalgesia in animals subjected to physiological stress (Kulkarni, 1980). Earlier work indicated that reserpine modified the analgesic actions of morphine (Medakovic and Banic, 1964). Though the exact mechanism of hyperalgesia is not known, the narcotic antagonist naloxone is reported to enhance nociceptive reactions in rats and mice (Jacob et al., 1974). Since the action of reserpine is mediated through its biogenic amine depleting property, one may correlate the hyperalgesic action to either catecholamine or serotonin depletion. In the present study dopaminergic substances (piribedil or amantadine) or antidepressants acting through a noradrenergic mechanism failed to reverse reserpine-induced hyperalgesia. On the other hand serotonin, its precursor, 5-HTP (Green and Grahame-Smith, 1976) or its agonist, quipazine (Rodriguez et al., 1973) significantly reversed the hyperalgesic action, thereby suggesting a role for serotonin in reserpine hyperalgesia. Recently, Garcia-Sevilla and coworkers (1978) have reported that opiate receptors and their endogenous ligands are involved in the regulation of dopamine and serotonin synthesis in rat brain. It is quite probable that alterations in the levels of these biogenic amines by drugs may also affect the sensitivity of opiate receptors. Reserpine-induced hyperalgesia may serve as a useful model for the selective study of serotonin mediated responses in rats. Acknowledgement
The present study was supported by the Indian National Science Academy, New Delhi. 4. Discussion
Reserpine-induced behavioural effects are considered to be due to the biogenic amine depleting property of the drug (Brodie et al., 1966). Pre-
References
Brodie, B.B., M.S. Comer, E. Costa and A. Dlabac, 1966, The role of brain serotonin in the mechanismof a central action
328 of reserpine, J. Pharmacol. Exp. Ther. 152, 340. Carlsson, A., M. Lindquist and T. Magnusson, 1957, 3,4-Dihydroxyphenylalanine and 5-hydroxytryptophan as reserpine antagonists, Nature 180. 1200. Costa, E., S. Garattini and L. Valzelli, 1960, Interactions between reserpine and chlorpromazine and imipramine, Experientia 16, 461. Domenjoz, R. and W. Tbeobold, 1959, Zur Pharmacologic des Tofranil, Arch. Int. Pharmacodyn. 120, 450. Garcia-Sevilla, J.A., L. Ahtee, T. Magnusson and A. Carlsson, 1978, Opiate receptor mediated changes in monoamine synthesis in rat brain, J. Pharm., Pharmacol. 30, 613. Green, A.R. and D.G. Graharne-Smith, 1976, ( - ) Propranolol inhibits the behavioural responses of rats to increased 5-hydroxytryptamine in the central nervous system, Nature 262, 594.
Jacob, J.J., E.C. Trembly and M.C. Colombel, 1974. Enhancement of nociceptive reactions by naloxone in mice and rats, Psychopharmacologia 37, 217. Kulkarrti, S.K., 1980, Heat and other physiological stress-induced analgesia: catecholamine mediated and naloxone reversible response, Life Sci. 27, 185. Medakovic, M. and B. Banic, 1964, The actions of reserpine and alpha-methyl-m-tyrosine on the analgesic effect of morphine in rats and mice, J. Pharm. Pharmacol. 16, 198. Noble, E., R.T. Wurtman and J. Axelrod, 1967, A simple and rapid method for injection of 3H-norepinephrine into the lateral ventricle of the rat brain, Life Sci. 6, 281. Rodriguez, R., J.A. Rojas-Ramirez and R.R. Drucker-Colin, 1973, Serotonin-like actions of quipazine on the central nervous system, European J. Pharmacol. 24, 164.
325
Elsevier Biomedical Press
Short communication REVERSAL BY S E R O T O N E R G I C A G E N T S OF R E S E R P I N E - I N D U C E D HYPERALGESIA
IN RATS SHRINIVAS K. KULKARNI and REJIT K. ROBERT
Pharmacology Division, Department of Pharmaceutical Sciences, Panjab University, Chandigarh, India Received 26 July 1982, acccepted 9 August 1982
S.K. KULKARNI and R.K. ROBERT, Reversal by serotonergic agents o/ reserpine-induced hyperalgesia in rats, European J. Pharmacol. 83 (1982) 325-328 Reserpine (4 mg/kg) induced a time-dependent reduction in pain threshold (hyperalgesia) as observed by the tail-flick technique in rats. Serotonin, its precursor 5-hydroxytryptophan or the receptor agonist, quipazine reversed the reserpine-induced hyperalgesia. On the other hand, piribedil, amantadine, imipramine or desipramine treatment failed to reverse the reserpine-induced hyperalgesia. Similarly, intracerebroventricular administration of dopamine or noradrenaline also had no effect on reserpine-induced hyperalgesia. These observations not only suggested a role of serotonin in hyperalgesia but also that reserpine hyperalgesia is suitable for selective study of serotonin-mediated responses in rats. 5-Hydroxytryptophan
Hyperalgesia
Reserpine
Quipazine
1. Introduction
While studying the role of catecholamines in stress analgesia we have found that reserpine produced hyperalgesia in animals (Kulkarni, 1980). Since reserpine depletes brain catecholamines and serotonin, and since brain monoamines are implicated in the regulation of pain perception and stress analgesia (Brodie et al., 1966; Carlsson et al., 1957; Medakovic and Banic, 1964; GarciaSevilla et al., 1978; Kulkarni, 1980), an attempt was made to investigate the mechanism of reserpine-induced hyperalgesia in rats.
2. Materials and methods
2.1. Animals and technique Wistar rats (150-200g) of either sex were used in the present study. The pain threshold to radiant heat was measured using an analgesiometer. Baseline latencies to tail-flick withdrawal from the radiant heat source ( 4 - 6 s ) were established. A 0014-2999/82/0000-0000/$02.75 © 1982 Elsevier Biomedical Press
Serotonin
minimum of 5 (2 min interval) trials were recorded for each animal before the test. Animals were tested at different intervals (l, 2, 4, 8 and 24h) after reserpine. Another group of rats were chronically implanted with polythelene cannulae into the right ventricle for intraventricular (i.c.v.) administration of biogenic amines (Noble et al., 1967). Each group consisted of a minimum of five animals. Statistical analysis was done using Student's t-test. 2.2. Drugs Reserpine (CIBA-Geigy) was administered in a dose of 4 m g / k g intraperitoneally (i.p.). Quipazine (10 mg/kg, Miles Laboratories), imipramine, desipramine (10 mg/kg), amantadine (20 mg/kg, Aldrich Chemicals) or piribedil (20 mg/kg) were administered i.p., 3.5 h after reserpine. 5-Hydroxytryptophan (5-HTP, 75 mg/kg, Sigma) and tranylcypromine (5 mg/kg, SKF, given 15 min before 5-HTP) were also administered 3.5 h after reserpine. The reaction time to radiant heat was also determined in these animals at 4, 8 and 24 h
326
! ....
Control
Re.,°t,,in~ O"~/k~) i
I
I 4
I
I e
Time
I z4
(~hours~after reserpine
Fig. I. Effect of reserpine (4 m g / k g ) on reaction time (s±S.E.M.) of rats to radiant heat as determined by tail-flick technique. Maximum reduction in the pain threshold (hyperalgesia) was observed at 4 h after reserpine. Each group consisted of a minimum of five rats.
ii f
[ ] Control ~/J Reserpine
,~. t= ~,.
[ ] Re,Lerpine+Drug
~
1~o
Control Tranyl cypromine
Ouipozine Amantodine~
pmmine Imiprom nePiribedil
+ 5-HTP Fig. 2. Histograms (s-S.E.M.) showing the reversal of reserpine ([])-induced hypcralgesia by various drug (B) treatments. 5-I-lydroxytr3,ptophan (5-HTP, 75 mg/kg)+ tranylcyprornine (5 mg/kg), quipazine (10 mg/kg), amantadine (20 mg/kg), imipramine (10 mg/kg), desipramine (10 mg/kg) and piril~lil (20 mg/kg) were administered i.p. 3.5 h after reserpine (4 mg/kg). Each group consisted of a minimum of five anima|s. * P<0.001 as compared to reserpine treatment.
327
after reserpine. The observations after 4 h of reserpine were used for statistical analysis as hyperalgesia was maximal at this time interval. Noradrenaline (10 /~g, Sigma), dopamine (60 /~g, Orient Pharma) and 5-hydroxytryptamine (20 p.g, Sigma) were administered i.c.v, in 20/~l saline with the help of a Hamilton microsyringe 3.5 h after reserpine. These doses were selected on the basis of earlier work in this laboratory.
3. Results
Reserpine produced a time-dependent reduction in pain threshold to radiant heat i.e. the reaction time was reduced. The maximum hyperalgesic effect was observed 4 h after reserpine and the animals recovered within 24 h following reserpine (fig. 1). Sedation, ptosis and diarrhoea were also seen in animals treated with reserpine. Quipazine did not show any effect of its own on the pain reaction in control animals but it significantly reversed the reserpine-induced hyperalgesia. On the other hand, 5-HTP and tranylcypromine given together showed an analgesic effect and also reversed the response reserpine. The animals were hyperactive and exhibited body tremors following this treatment. The effect lasted upto 24h and mortality (2/5) was observed in this group (fig. 2). Intraventricular administration of noradrenaline (t -~ 1.3) and dopamine (t = 0.2) did not have any effect while 5-hydroxytryptamine significantly (t = 3.7, P < 0.001) reversed the reserpine hyperalgesia. In contrast to serotonergic agents, dopamine agonists like piribedil or amantadine failed to reverse the reserpine-induced hyperalgesia. Similarly, tricylic antidepressants like imipramine or desipramine failed to reverse the response to reserpine though these agents antagonized the reserpine-induced sedation in rats (fig. 2).
cursors of catecholamine and serotonin reverse not only the behavioural effects but also the biochemical changes caused by reserpine (Carlsson et al., 1957). Certain antidepressant drugs are also reported to reverse both behavioural and cardiovascular effects of reserpine (Domenjoz and Theobold, 1959; Costa et al., 1960). Recently it has been reported that reserpine induced hyperalgesia in animals subjected to physiological stress (Kulkarni, 1980). Earlier work indicated that reserpine modified the analgesic actions of morphine (Medakovic and Banic, 1964). Though the exact mechanism of hyperalgesia is not known, the narcotic antagonist naloxone is reported to enhance nociceptive reactions in rats and mice (Jacob et al., 1974). Since the action of reserpine is mediated through its biogenic amine depleting property, one may correlate the hyperalgesic action to either catecholamine or serotonin depletion. In the present study dopaminergic substances (piribedil or amantadine) or antidepressants acting through a noradrenergic mechanism failed to reverse reserpine-induced hyperalgesia. On the other hand serotonin, its precursor, 5-HTP (Green and Grahame-Smith, 1976) or its agonist, quipazine (Rodriguez et al., 1973) significantly reversed the hyperalgesic action, thereby suggesting a role for serotonin in reserpine hyperalgesia. Recently, Garcia-Sevilla and coworkers (1978) have reported that opiate receptors and their endogenous ligands are involved in the regulation of dopamine and serotonin synthesis in rat brain. It is quite probable that alterations in the levels of these biogenic amines by drugs may also affect the sensitivity of opiate receptors. Reserpine-induced hyperalgesia may serve as a useful model for the selective study of serotonin mediated responses in rats. Acknowledgement
The present study was supported by the Indian National Science Academy, New Delhi. 4. Discussion
Reserpine-induced behavioural effects are considered to be due to the biogenic amine depleting property of the drug (Brodie et al., 1966). Pre-
References
Brodie, B.B., M.S. Comer, E. Costa and A. Dlabac, 1966, The role of brain serotonin in the mechanismof a central action
328 of reserpine, J. Pharmacol. Exp. Ther. 152, 340. Carlsson, A., M. Lindquist and T. Magnusson, 1957, 3,4-Dihydroxyphenylalanine and 5-hydroxytryptophan as reserpine antagonists, Nature 180. 1200. Costa, E., S. Garattini and L. Valzelli, 1960, Interactions between reserpine and chlorpromazine and imipramine, Experientia 16, 461. Domenjoz, R. and W. Tbeobold, 1959, Zur Pharmacologic des Tofranil, Arch. Int. Pharmacodyn. 120, 450. Garcia-Sevilla, J.A., L. Ahtee, T. Magnusson and A. Carlsson, 1978, Opiate receptor mediated changes in monoamine synthesis in rat brain, J. Pharm., Pharmacol. 30, 613. Green, A.R. and D.G. Graharne-Smith, 1976, ( - ) Propranolol inhibits the behavioural responses of rats to increased 5-hydroxytryptamine in the central nervous system, Nature 262, 594.
Jacob, J.J., E.C. Trembly and M.C. Colombel, 1974. Enhancement of nociceptive reactions by naloxone in mice and rats, Psychopharmacologia 37, 217. Kulkarrti, S.K., 1980, Heat and other physiological stress-induced analgesia: catecholamine mediated and naloxone reversible response, Life Sci. 27, 185. Medakovic, M. and B. Banic, 1964, The actions of reserpine and alpha-methyl-m-tyrosine on the analgesic effect of morphine in rats and mice, J. Pharm. Pharmacol. 16, 198. Noble, E., R.T. Wurtman and J. Axelrod, 1967, A simple and rapid method for injection of 3H-norepinephrine into the lateral ventricle of the rat brain, Life Sci. 6, 281. Rodriguez, R., J.A. Rojas-Ramirez and R.R. Drucker-Colin, 1973, Serotonin-like actions of quipazine on the central nervous system, European J. Pharmacol. 24, 164.