[Change in dopamine and serotonin receptor sensitivity following chronic chlorpromazine administration].

Stereotypy elicited by apomorphine, or hyperactivity syndrome (head twitches) induced by 1-tryptophane plus phenelzine was studied in rats during 20 days following chlorpromazine administration for 10 days (10 mg/kg daily). Significant intensification of behavioural effect of apomorphine and especially of 1-tryptophane was observed in neuroleptically pretreated rats. These results point to the development of hypersensitivity of dopamine and serotonin receptors to agonists following chlorpromazine pretreatment. It is suggested that increase in the sensitivity of dopamine and serotonin receptors is of importance for the development of hyperkinetic syndrome during neuroleptic treatment.