Differential effects of some predominantly antiadrenergic and antidopaminergic neuroleptics on the preovulatory surge of FSH, LH and prolactin in rat.

In experiments performed on rats, single subcutaneous doses of predominantly antiadrenergic neuroleptics (thioridazine, propericiazine) significantly depressed the preovulatory serum LH surge. On the contrary, predominantly antidopaminergic drugs (pimozide and in lesser extent thiethylperazine) elevated the circulating LH levels, and reduced pituitary LH content. FSH titers were not altered significantly (excepting by thioridazine). All the neuroleptics increased serum prolactin. The present results, in conjunction with our previous data obtained on the estrous cycle, suggest a stimulatory role of norepinephrine/epinephrine in LH-RH secretion and an inhibitory action of dopamine on the same process. In our experiments only the predominantly antidopaminergic drugs had a pseudopregnancy-inducing effect, which not only elevated PRL levels, but also allowed (rather increased) preovulatory LH surge, and the subsequent development of new corpora lutea. The lack of pseudopregnancy after predominantly antiadrenergic neuroleptics may be attributed mainly to their antiovulatory action preventing the development of fresh corpora lutea.