Amphetamine stereotypy in cats and neurotransmitter interactions in the caudate nucleus. I. Effects of intracaudate injections of haloperidol, GABA and bicuculline.

Intracaudate (into the rostrodorsal part of the caudate nucleus) injection of haloperidol in free moving cats did not modify spontaneous or d-amphetamine-induced stereotyped behavior, while administered intraperitoneally, haloperidol blocked the stereotypy. These results, in accordance with some views, suggest that in this region of the caudate nucleus, the dopamine inhibitory receptors prevail over the excitatory ones. The effects of intracaudate bicuculline (decrease in the number of all stereotyped movements, increase in the number of ipsilateral amphetamine-induced or spontaneous head movements over the contralateral ones) were more pronounced than those of intracaudate GABA (increase only in the number of nonfocused lickings). The present results support the view that interactions between dopamine and GABA occur in the caudate nucleus in cats during amphetamine stereotypy.