Inhibition of Apomorphine‐Induced Climbing in Mice by Cholinergic Drugs and Neuroleptics

Abstract

Apomorphine (ap) was administered s.c. to mice kept in individual cages. Ap elicited an abnormal vertical climbing behavior. The muscarinomimetics physostigmine and oxotremorine and the neuroleptics clozapine and haloperidol inhibited the climbing produced by ap 1 mg/kg. A small inactive dose of physostigmine potentiated the effect of clozapine but not that of haloperidol. The anticholinergic atropine antagonized the effect of physostigmine, oxotremozine, clozapine and haloperidol. The climbing behavior produced by ap may be due to stimulation of dopamine receptors and the effect can be antagonized either by dopamine receptor blockade or by muscarinic receptor activation. The ap-inhibitory effect of clozapine may be partly due to a muscarinomimetic effect.