Potentiation of licking in rats by stimulation of both D-1 and D-2 dopamine receptors

Abstract

Apomorphine-induced licking in rats was assessed by recording the total number of licks by direct observation. Apomorphine induced licking dose dependently. The maximum response was obtained by 0.5 mg/kg of the drug and 30 min after drug administration. Pre-treatment with dopamine antagonists, sulpiride and SCH 23390 decreased the apomorphine effect. Pre-treatment of animals with reserpine+α-methyl-p-tyrosine (AMPT) increased apomorphine-induced licking. In normal rats the D-2 agonist quinpirole and the D-1 agonist SKF 38393 also induced significant licking. The effect of quinpirole or SKF 38393 was decreased by reserpine+AMPT pre-treatment. Combined treatment with SKF 38393 and quinpirole induced more intense licking in both reserpinized and non-reserpinized animals. It is therefore concluded that the apomorphine-induced licking is mediated through both D-1 and D-2 receptors, and that pre-treatment with reserpine hypersensitizes these receptors to the drug effect. However, for either SKF 38393- or quinpirole-induced licking, the presence of endogenous dopamine seems essential.

Keywords

D-1 and D-2 receptors apomorphine quinpirole SKF 38393 reserpine licking rats

References

Anden N.E. , Rubensson A. , Fuxe K. , Hokfelt T. (1967) Evidence of dopamine receptor stimulation by apomorphine . J Pharm Pharmacol 19: 627-629

Arnt J. , Hyttel J. , Perregaard J. (1987) Dopamine D-1 receptor agonists combined with the selective D-2 agonist quinpirole facilitate the expression of oral stereotyped behaviour in rats. Eur J Pharmacol 133: 137-145

Barone P. , Davis T.A. , Braun A.R. , Chase TN (1986) Dopaminergic mechanisms and motor function: Characterization of D-1 and D-2 dopamine receptor interactions. Eur J Pharmacol 123: 109-114

Braun A. , Chase T.N. (1986) Obligatory D-1/D-2 receptor interaction in the generation of dopamine agonist related behaviours. Eur J Pharmacol 131: 301-306

Di Chiara G. , Porceddu M.L. , Vargiu L. , Argiolas A. , Gessa G.L. (1976) Evidence for dopamine receptors in the mouse brain mediating sedation. Nature 264: 564-567

Ernst AM (1967) Mode of action of dopamine and dexamphetamine in gnawing compulsion in rats. Psychopharmacology 10: 316-323

Gershanik O. , Heikkila R E W , Duvoisin R.C. (1983) Behavioural correlates of dopamine receptor activation . Neurology 33: 1489-1492

Havemann U. , Magnus B. , Moller H.G. , Kuschinsky K. (1986) Individual and morphological differences in the behavioural response to apomorphine in rats. Psychopharmacology 90: 40-80

Hess E.J. , Alberts L.J. , Le H. , Creese I. (1986) Effects of chronic SCH 23390 treatment on the biochemical and behavioural properties of D-1 and D-2 dopamine receptors: Potentiated behavioural responses to a D-2 dopamine agonist after selective D-1 dopamine receptor upregulation. J Pharmacol Exp Ther 238: 846-854

10.

Hyttel J. (1983) SCH 23390 the first selective dopamine antagonist . Eur J Pharmacol 91: 153-154

11.

Hyttel J. (1984) Functional evidence for selective dopamine D-1 receptor blockade by SCH 23390. Neuropharmacology 23: 1395-1401

12.

Kebabian J.W. , Calne D.B. (1979) Multiple receptors for dopamine. Nature 277: 93-96

13.

Kelly P.H. , Seviour P.W. , Iversen S.D. (1975) Amphetamine and apomorphine responses in the rat following 6-OHDA lesions of the nucleus accumbens, septi and corpus striatum . Brain Res 94: 507-522

14.

Seeman P. (1980) Brain dopamine receptors. Pharmacol Rev 32: 229-313

15.

Setler P. , Sarau H.M. , Zirkle C.L. , Saunders H.L. (1978) The central effect of a novel dopamine agonist . Eur J Pharmacol 50: 419-430

16.

Stoof J.C. , Kebabian J.W. (1984) Two dopamine receptors: biochemistry, physiology and pharmacology. Life Sci 35: 2281-2296

17.

Ungerstedt U. (1979) Central dopamine mechanisms and unconditioned behaviour . In: Horn A S , Westernik B H D (eds), The neurobiology of dopamine. Academic Press, London/New York /San Francisco, pp. 577-596

18.

Van Ree J.M. , Wolternik G. (1981) Injection of low doses of apomorphine into the nucleus accumbens of rats reduces locomotor activity. Eur J Pharmacol 72: 107-111

19.

Waddington J.L. , O'Boyle K M. (1989) Drugs acting on brain dopamine receptors: a conceptual re-evaluation five years after the first selective D-1 antagonist. Pharmacol Ther 43: 1-52