Catalepsy and circling behaviour after intracerebral injections of neuroleptic, cholinergic and anticholinergic agents into the caudate-putamen, globus pallidus and substantia nigra of rat brain

Abstract

Haloperidol, arecoline and atropine were injected in various combinations into the caudate-putamen, globus pallidus and substantia nigra. Unilateral injections of haloperidol or arecoline into the caudate-putamen, globus pallidus or substantia nigra induced an ipsilateral circling behaviour, the globus pallidus being the most sensitive and the substantia nigra the least sensitive to this effect. Atropine induced a contralateral circling behaviour after injection into the caudate-putamen or globus pallidus and in each case potentiated the ipsilateral circling of haloperidol and arecoline when injected into the opposite nucleus. The injection of atropine into the same caudate-putamen as haloperidol or arecoline inhibited the ipsilateral circling induced by the latter drugs. Catalepsy was observed after haloperidol injections into the caudate-putamen and globus pallidus, the latter nucleus being the most sensitive. Catalepsy was not observed after arecoline injection into any of the nuclei considered. The bilateral injection of atropine into the caudate-putamen and globus pallidus did not modify the catalepsy induced by peripheral administration of haloperidol or arecoline but intranigral atropine markedly potentiated the cataleptic effects of these drugs. Results are discussed in terms of cholinergic and dopaminergic mechanisms within the extrapyramidal system.