MULTIUNIT ACTIVITY FROM THE A9 AND A10 AREAS IN RATS FOLLOWING CHRONIC TREATMENT WITH DIFFERENT NEUROLEPTIC DRUGS

Effects of repeated twice daily i.p. administration of haloperidol (0. 5 mg/kg), clozapine (3.0 mg/kg) and prothipendyl (1.0 mg/kg) on sponta neous A9 and A10 cell activity were studied using extracellular multiu nit recording in rats, which offers relatively rapid access to neural activity in a large number of cells. Two cell types were identified, w hich probably represent the putative dopaminergic and non-dopaminergic neurons. Repeated neuroleptic treatment reduced the number of spontan eously active type 1 A10 cells per track. The effect of haloperidol wa s more pronounced than that of clozapine or prothipendyl. A9 cells wer e affected by haloperidol only. The frequency and amplitude of A9 and A10 active cells remained quite stable, except for a clozapine-induced increase of their values for type 1 A10 cells. Stability of spontaneo usly active type 1 A10 cells was significantly reduced by the chronic neuroleptic treatment. Collectively the activity of type 2 cells was n ot altered. Prothipendyl was classified as an atypical neuroleptic dru g with potency comparable to clozapine.