Cataleptogenic potency of the antipsychotic drugs is inversely correlated with neuronal activity in the amygdaloid complex of the rat

At doses known to elicit catalepsy in rats, haloperidol (1.0 and 2.0 mg/kg) and pimozide (4.0 mg/kg), injected intraperitoneally, failed to alter the spontaneous activity of neurons in the amygdaloid complex of locally anesthetized, immobilized rats. In contrast, clozapine and thioridazine, which are devoid of cataleptic effects even at high doses (10.0 and 20.0 mg/kg), caused a dramatic and prolonged increase in firing rate, whereas chlorpromazine, which produces relatively mild catalepsy at doses of 5.0 and 10.0 mg/kg, produced an intermediate response. These results, which were obtained throughout the amygdaloid complex, indicate that the cataleptogenic potency of the antipsychotic drugs is inversely correlated with their ability to accelerate neuronal activity. This finding is discussed in relation to the known mechanisms of action of these drugs on various neurotransmitter systems in the amygdaloid complex.