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 spontaneous A9 and A10 cell activity were studied using extracellular multiunit recording in rats, which offers relatively rapid access to neural activity in a large number of cells. Two cell types were identified, which probably represent the putative dopaminergic and non-dopaminergic neurons. Repeated neuroleptic treatment reduced the number of spontaneously active type 1 A10 cells per track. The effect of haloperidol was more pronounced than that of clozapine or prothipendyl. A9 cells were 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 spontaneously active type 1 A10 cells was significantly reduced by the chronic neuroleptic treatment. Collectively the activity of type 2 cells was not altered. Prothipendyl was classified as an atypical neuroleptic drug with potency comparable to clozapine.