The different influence of predominantly antiadrenergic and antidopaminergic neuroleptics on the estrous cycle in rats.

In experiments performed on rats, single subcutaneous doses of predominantly antidopaminergic neuroleptics (fluspirilene, pimozide, and thioproperazine in large doses) elicited persistent diestrus, i.e. pseudopregnancy. Neuroleptics with predominantly antiadrenergic action (levomepromazine, thioridazine, chlorpromazine) as well as phenoxybenzamine injected intraventricularly induced mainly prolonged estrus, i.e. blocking of ovulation. Since pseudopregnancy implies a rise of prolactin secretion, our results indirectly indicate that PIF secretion is stimulated by dopamine. The antiovulatory effect of the antiadrenergic agents, which involves an inhibition of the proestral LH surge, suggests that the discharge of LRF is mediated by an adrenergic mechanism.