NEUROLEPTIC AND MUSCARINIC

Transcription

1 Br. J. Pharma. (1975), 54, THE INTERACTION OF NEUROLEPTIC AND MUSCARINIC AGENTS WITH CENTRAL DOPAMINERGIC SYSTEMS P.H. KELLY Department of Experimental Psyhology, Downing Street, Cambridge R.J. MILLER M.R.C. Neurohemial Pharmaology Unit, Department of Pharmaology, Medial Shool, Hills Road, Cambridge CB2 2QD 1 The effet of musarini and neurolepti agents on the turning behaviour indued by methamphetamine and apomorphine in rats with unilateral lesions of the substantia nigra indued by 6-hydroxydopamine has been examined. 2 Turning towards the side of the lesion indued by (+)-methamphetamine (5 mg/kg) was inhibited by a-flupenthixol (1 mg/kg) and a-lopenthixol (8 mg/kg) but not by high doses of their,6-isomers. 3 Turning was inhibited by hlorpromazine (4 mg/kg) and pimozide (0.2 mg/kg). Thioridazine and lozapine (16 mg/kg) were ineffetive. Turning in the same diretion produed by sopolamine ( mg/kg) was also inhibited by a-flupenthixol (1 mg/kg) and pimozide (0.25 mg/kg). 4 Tuming produed by methamphetamine (5 mg/kg) was inhibited by oxotremorine (0.75 mg/kg) even in the presene of methylatropine (5 mg/kg). 5 Tuming away from the side of the lesion indued by apomorphine (0.1 mg/kg) was inhibited by oxotremorine (0.75 mg/kg) but not by thioridazine or lozapine (16 mg/kg). 6 These results are disussed with regard to the mode of ation of neurolepti drugs in produing anti-psyhoti effets and drug-indued Parkinsonism. Introdution Apart from their therapeuti antipsyhoti ation neurolepti drugs may produe unwanted sideeffets. One ommonly observed side-effet is the ourrene of drug-indued parkinsonian symptoms (Klawans, 1973). Both the antipsyhoti ation and the extrapyramidal parkinsonian side-effets of the neurolepti drugs generally orrelate well with their poteny in bloking dopamine reeptors as revealed by in vitro (Clement-Cormier, Kebabian, Petzold & Greengard, 1974; Horn, Cuello & Miller, 1974; Miller, Horn & Iversen, 1974) and in vivo (Anden, Buther, Corrodi, Fuxe & Ungerstedt, 1970) models. However, it has been reported that some neuroleptis, notably thioridazine and lozapine, produe only minimal parkinsonian symptoms (Cole & Clyde, 1961; Burki, Ruh, Asper, Baggiolini & Stille, 1973) although they are potent blokers of dopamine effets in vitro (Miller et al., 1974). Sine drug-indued extrapyramidal effets an be alleviated by antimusarini drugs (Shintami & Yamamura, 1973) it is possible that the reently demonstrated antimusarini ation of lozapine and thioridazine (Miller & Hiley, 1974; Snyder, Greenberg & Yamamura, 1974) might aount for their prodution of only minimal parkinsonian side-effets. Parkinsonism is related to defiient striatal dopaminergi funtion (Hornykiewiz, 1973) and drug-indued Parkinsonism may therefore result from blokade of striatal dopamine reeptors. A possible basis for the alleviation of parkinsonian symptoms by antimusarini agents is the observed antagonisti effets of musarini agents and drugs ating on dopamine reeptors in the striatum (Costall, Naylor & Olley, 1972). In the present investigation we have used the rotation of rats with unilateral degeneration of the nigrostriatal pathway (Ungerstedt & Arbuthnott, 1970; Ungerstedt, 1971) as a quantitative in vivo

2 116 P.H. KELLY & R.J. MILLER model of striatal dopaminergi ativity to study the ation of holinomimeti agents and neuroleptis on striatal dopaminergi mehanisnms. Methods Male albino Sprague-Dawley rats ( g at the time of surgery) were given food and water ad libitum during the period of use. Lesions Animals were anaesthetized with Equithesin (Jensen-Salsbery Labs.), 2.5 ml/kg. They were then positioned in a stereotaxi apparatus and injeted unilaterally with 6-hydroxydopamine through a 30 gauge stainless steel annula aimed at the substantia nigra. The o-ordinates of the annula tips were 2.8, 2.0, 8.0 aording to the atlas of Pellegrino & Cushman (1967). 6-1lydroxydopamine hydrobromide was freshly dissolved (2 mg of base per ml) in old 0.9% w/v NaCl solution (saline) ontaining 1 mg/ml of asorbi aid; 4 pl of this solution was injeted through the annula at a rate of I,l/minute. Turning behaviour Drugs were made up in saline. The doses were alulated as the forms given below. Pimozide was first dissolved in a drop of glaial aeti aid and then diluted. Clozapine was dissolved with an equal weight of tartari aid. Injetion of vehile solutions of these drugs into rats did not affet turning behaviour. All drugs were given intraperitoneally, exept for apomorphine whih was given subutaneously. Fourteen days after the injetion of 6-hydroxydopamine, the animals were sreened for ability to tum with apornorphine (0.5 mg/kg) and (+)-methamphetamine (5 mg/kg). Only animals whih responded with at least ten turns per minute were retained. Animals used in experiments with methamphetamine-indued turning were sreened at least days after operation, and those on apomorphine turning after at least three weeks. After initial seletion, the animals were separated into groups of 4 or 5 animals and used in experiments withi various drugs, at intervals of at least one week. The ontrol responses of the various groups to methamphetamine and apomorphine during the period of the experiments did not hange signifiantly. The experimental proedure was as follows. Animals were injeted with the test drugs or vehiles 3 h before the experiments with the exeption of oxotremorine whih was given 5 min after the amphetamine or apomorphine. At the C4~ E' ) I I I Time (min) Figure 1 Effet of different isomers of thioxanthene neuroleptis on turning behaviour indued by methamphetamine (5 mg/kg). (a) Turning after mg/kg,-flupenthixol (-). (b) Turning after 0.2 mg/kg (m) or 1.0 mg/kg (A) al-flupenthixol and saline ontrol (o). () Turning after 8 mg/kg a- (A) or 3-lopenthixol (o) and saline ontrol (o). Results are means from four rats. Vertial bars show s.e. mean. time of the experiment animals were injeted with amphetamine or apomorphine and then plaed in individual ages. All animals in a group reeived the same drug treatments. At 30 min,intervals animals were plaed in rotometer bowls for 5 minutes. The number of turns per min was measured on the fifth min by diret observation. The rotometers onsisted of white perspex transluent bowls supported on metal rings. The bowls measured 30 m in diameter and 26 m in height. Drugs The following drugs were used: (+)-methamphetamine hydrohloride, 6-hydroxydopamine

3 INTERACTION OF NEUROLEPTIC AND MUSCARINIC DRUGS 117.'E L/..d Eb o Time(min) Figure 2 Effet of pimozide and hlorpromazine on methamphetamine- (5 mg/kg) indued turning behaviour. (a) Turning after 0.25 mg/kg pimozide (s) or saline (-). (b) Turning after 4 mg/kg hlorpromazine (A) or saline (-). Results are means from four rats. Vertial bars show s.e. mean. hydrobromide, (Sigma); thioridazine hydrohloride (Sandoz); lozapine (base) (Sandoz/ Wander); sopolamine hydrohloride (BDH); apomorphine hydrohloride (MaFarlane Smith); oxotremorine sesquifumarate (Aldrih); pimozide (base) (Janssen); a- and,b-flupenthixol and a- and,b-lopenthixol dihydrohloride (Lundbek). Results Blokade of methamphetamine-indued turning by is- and trans-thioxan thene isomers In aordane with previous reports (Ungerstedt & Arbuthnott, 1970) intraperitoneal injetion of methamphetamine in lesioned animals produed turning towards the side of the lesion in a dose-dependent fashion. The thioxanthene neuroleptis flupenthixol and lopenthixol exhibit geometri isomerism, existing as is (ai) or trans (f3) isomers. Previously we have shown that only the ai-isomers are effetive antagonists of the dopamine-stimulated adenylate ylase in homogenates of rat striatum. Figure 1 shows the effets of the different isomers on turning produed by 5 mg/kg of methamphetamine. For both neuroleptis the,3-isomers were ineffetive whereas the a-isomers were effetive in bloking suh turning. ax-flupenthixol was more potent than a-lopenthixol. This again parallels the ativity of the drugs on the dopamine-sensitive adenylate ylase. Effets of other neuroleptis Pimozide (Figure 2) ompletely abolished tuming behaviour at low doses. At 4 mg/kg hlorpromazine partially inhibited turning (Figure 2). This result is similar to that reported by Crow & Gillbe (1973). These authors also showed that

4 118 P.H. KELLY & R.J. MILLER U) H- 301 a Effet of musarini agents When 0.75 mg/kg oxotremorine was 201 administered just after methamphetamine (5 mg/kg) the resulting turning behaviour was onsiderably 1 redued. In order to see whether this blokade of turning was due to entral or peripheral effets of oxotremorine, some animals were also given mg/kg of methylatropine, to blok peripheral musarini reeptors. In these animals oxob tremorine (0.75 mg/kg) 301 still produed a onsiderable derease in methamphetamine-indued turning behaviour (Figure 3). In onfirmation of 201 previous reports (Ungerstedt, Avemo, Avemo, Ljungberg & Ranje, 1973), the antimusarini drug sopolamine ( mg/kg) produed turning behaviour in the same diretion as methamphetamine. However, sopolamine was onsiderably less effetive than methamphetamine Sopolamine-indued turning ould be inhibited Time (min) by a-flupenthixol and pimozide (Figure 4). Figure 3 Effet of oxotremorine on turning behaviour indued by methamphetamine (5 mg/kg). (a) Turning after 0.75 mg/kg oxotremorine (U) given 5 min after the amphetamine and saline ontrol (.). (b) Effet of 0.75 mg/kg oxotremorine and 5 mg/kg methylatropine (A) given 5 min after the amphetamine. Results are means from four rats. Vertial bars show s.e. mean. higher doses of hlorpromazine ompletely bloked turning. In ontrast the two neuroleptis lozapine and thioridazine had no effet on turning behaviour even at very high doses (16 mg/kg). Similar observations with thioridazine at lower doses have been reported previously (Crow & Gillbe, 1973). Effet of drugs on apomorphine-indued turning When animals were given apomorphine, a diretly ating dopamine reeptor agonist, the animals turned away from the side of the lesion in a dose-dependent fashion. This phenomenon has been attributed to the ation of apomorphine on supersensitive reeptors on the lesioned side (Ungerstedt, 1971). Turning ould be eliited by very low doses of apomorphine, down to 0.01 mg/kg. With doses of 0.05 mg/kg or higher the maximal number of turns per minute did not inrease but the duration of tuming did. It was found that oxotremorine (0.75 mg/kg) redued apomorphine-indued turning (Figure 5). It was Time (min) I i --i Figure 4 Turning towards the side of the lesion produed by sopolamine ( mg/kg) (-). The turning was bloked by pimozide (0.25 mg/kg) (a) or t-flupenthixol (1.0 mg/kg) (a). Results are means from four rats. Vertial bars show s.e. mean.

5 INTERACTION OF NEUROLEPTIC AND MUSCARINIC DRUGS 119 a 20r o H. Time (min) b 20r I ~~~~~ I Figure 5 Effet of oxotremorine 0.75 mg/kg (a) or saline (e) given 5 min after apomorphine on turning behaviour produed by 0.1 mg/kg apomorphine. Results are means from four rats. Vertial bars show s.e. mean. also found that lozapine and thioridazine (16 mg/kg) were ineffetive in inhibiting apomorphine-indued turning (Figure 6). Disussion In the present investigation we have onfirmed that some neurolepti drugs are able to blok the methamphetamine-indued rotation of rats with unilateral degeneration of the nigrostriatal pathway. The poteny of hlorpromazine and the a- and 3-isomers of flupenthixol and lopenthixol as amphetamine antagonists in this test orrelated well with the dopamine bloking potenies of these drugs previously measured in an in vitro biohemial system (Miller et al., 1974). However, the neuroleptis thioridazine and lozapine did not blok the turning provoked by methamphetamine or apomorphine even in high doses. On the basis of their original observation that thioridazine did not blok methamphetamine-indued turning Crow & Gillbe (1973) suggested that thioridazine does not blok dopamine reeptors. However, both lozapine and thioridazine are potent blokers of the stimulation by dopamine of adenylate ylase in homogenates of the rat striatum (Miller et al, 1974), an in vitro system whih has proved a useful model of the dopamine reeptor. An alternative explanation of the failure of thioridazine and also of lozapine to blok methamphetamine-indued rotation is that their antimusarini ation (Miller & Hiley, 1974; Snyder et al., 1974) may alleviate the anti- a'! Time(min) Figure 6 Effet of lozapine and thioridazine on turning indued by apomorphine (0.1 mg/kg). (a) Effet of thioridazine (16 mg/kg) (s) and saline ontrol (-). (b) Effet of lozapine (16 mg/kg) (A). Results are means from four rats. Vertial bars show s.e. mean. dopaminergi effets of this drug in the striatum. We have demonstrated that entral holinergi stimulation produed by oxotremorine an blok methamphetamine-indued turning and onversely that the antimusarini agent sopolamine produes turning in the same diretion as methamphetamine. The neuroanatomial basis of these holinergidopaminergi interations ould involve both the substantia nigra and the striatum. Loal appliation of holinomimeti agents to the substantia nigra dereases the turnover of dopamine in nigrostriatal dopaminergi neurones, while antimusarini drugs have the opposite effet (Javoy, Agid, Bouvet & Glowinski, 1974), suggesting that holinergi synapses are involved in an inhibitory effet on nigrostriatal neurones. The turning produed by the anti-aetylholine agent,

6 120 P.H. KELLY & R.J. MILLER sopolamine, may involve ativity in the intat nigrostriatal dopaminergi neurones, siiie this turning ould be bloked by dopamine reeptor bloking drugs suh as pimozide and y-flupenthixol. A further site of holinergi-dopaininergi interation is probably the striatum itselt. In the present investigation we have observed that the turning produed by the dopamine agonist apomorphine is inhibited by the holinomimeti agent oxotremorine. Sine apomorphine-indued turning is thought to result from the diret stimulation of the supersensitive denervated striatal dopamine reeptors (Ungerstedt, 1971), the effet of oxotremorine on apomorphineindued turning does not depend on an ation on nigrostriatal dopaminergi neurones. One mehanism whih may be important in the effet of oxotremorine on apomorphine-indued turning is an inrease of striatal holinergi ativity. This would tend to antagonize dopaminergi ativity sine there is evidene that dopamine inhibits holinergi interneurones in the striatum. For example, blokade of dopaminergi transmission by neuroleptis inreases the release of- aetylholine from the audate nuleus (Stadler, Lloyd, Gadea-Ciria & Bartholini, 1973) and redues striatal levels of aetylholine (Sethy & Van Woert, 1974; Agid, Guyenet, Javoy, Beaujouian & Glowinski, 1974). Treatment with dopamine agonists suh as apomorphine and L-DOPA inreases striatal levels of aetylholine (Sethy & Van Woert, 1974). In onlusion, using the rotation model we have demonstrated an inhibitory interation between holinergi ativity and dopaminergi ativity in the extrapyramidal system. Evidene has been disussed that this interation an our both in the substantia nigra and in the striatum itself. These interations may explain why neurolepti drugs suh as thioridazine and lozapine whih possess both antidopaminergi and antimusarini ations do not blok the turning behaviour produed by dopamine release (methamphetamine) or by diret stimulation of dopamine reeptors (apomorphine). The antimusarini ations of these drugs may also be responsible at least in part, for their lak of prodution of extrapyramidal symptoms when used linially. Their therapeuti antipsyhoti ativity may therefore result from blokade of dopamine reeptors other than those in the striatum. R.M. is an M.R.C. Sholar. P.H.K. aknowledges the support of an ICI Fellowship. We are indebted to Lundbek Ltd. for supplies of thioxanthene isomers, to Sandoz/Wander for lozapine and thioridazine and to Janssen Pharmaeutia for pimozide. We also aknowledge help and advie from Drs L.L. and S.D. Iversen during the ourse of this study. Referenes AGID, Y., GUYENET, P., JAVOY, F., BEAUJOUIAN, J.C. & GLOWINSKI, J. (1974). Speifi aspets of antagonists and agonists of DA reeptors on Ah turnover in the rat neostriatum. J. de Pharmrraologie, 5, Suppl. 1, 59. ANDEN, N-E., BUTCHER, S.G., CORRODI, H., FUXE, K. & UNGERSTEDT, U. (1970). Reeptor ativity and turnover of dopamine and noradrenaline after neuroleptis. Eur. J. Pharma., 11, BURKI, H.R., RUCH, W., ASPER, H., BAGGIOLINI, M. & STILLE, G. (1973). Pharmakologishe und neurohemishe Wirkungen von Clozapin. Neue Gesihtspunkte in der medikamentosen Behandlung der Shizophrenie. Shweiz. Med. Wohenshr., 3, CLEMENT-CORMIER, Y.C., KEBABI AN J.W.. PETZOLD, G.L. & GREENGARD, P. (1974). Dopamine sensitive adenylate ylase in mammalian brain: a possible site of ation of antipsyhoti drugs. Pro. Nat. aad. Si. U.S.A., 71, COLE, J.O. & CLYDE, D.J. (1961). Extrapyramidal side effets and linial response to the phenolhiazines. Revue Canadienne de Biologie, 20, COSTALL, B., NAYLOR, R.J. & OLLEY, J.E. (1972). Catalepsy and turning behaviour after intraierebral injetions of neurolepti, holinergi and antiholinergi agents into the audate-putamen, globus pallidus and substantia nigra of rat brain. Neuropharmaology, 11, CROW, T.J. & GILLBE, D. (1973). Dopamine antagonism and antishizophreni poteny of neurolepti drugs. Nature New Biol., 245, HORN, A.S., CUELLO, A.C. & MILLER, R.J. (1974). Dopamine in the mesolimbi system of the rat brain: endogenous levels and the effet of drugs on the uptake mehanism and stimulation of adenylate ylase ativity. J. Neurohem., 22, HORNYKIEWICZ, 0. (1973). Dopamine in the basal ganglia: its role and therapeuti impliations (inluding the linial use of L-DOPA). Brit. Med. Bull., 29, JAVOY, F., AGID, Y., BOUVET, D. & GLOWINSKI, J. (1974). Changes in neostriatal dopamine metabolism after arbahol or atropine miroinjetions into the substantia nigra. Brain Researh, 68, KLAWANS, H.L. (1973). The Pharmaology of Extrapyramidal Movement Disorders. Basel: S. Karger. MILLER, R.J. & HILEY, C.R. (1974). Antimusarini properties of neurolepti drugs and drug indued parkinsonism. Nature, Lond., 248, MILLER, R.J., HORN, A.S. & IVERSEN, L.L. (1974). The ation of neurolepti drugs on dopamine

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