The anti-oestrogen tamoxifen does not interfere with the dopaminergic control of prolactin and TSH release in normogonadotrophic oligozoospermic man.

This study was designed to investigate the role of endogenous oestrogens in the dopaminergic regulation of prolactin and TSH release in 16 normogonadotrophic oligozoospermic men. Three months' administration of the oestrogen-receptor antagonist tamoxifen (10 mg twice daily), blocking oestrogen-receptors both in the CNS and peripherally, did not affect basal prolactin and TSH levels. Neither was the prolactin or TSH response to stimulation with the anti-dopaminergic agents metoclopramide (10 mg i.v.) (acting both in the CNS and peripherally) and domperidone (10 mg i.v.) (acting peripherally) affected by tamoxifen administration. The response of prolactin and TSH to metoclopramide proved to be no greater than to domperidone. It is concluded that: Endogenous oestrogens, in as far as receptor-mediated, do not affect basal or anti-dopaminergic stimulated release of both prolactin and TSH in normogonadotrophic oligozoospermic men. The anti-dopaminergic activity of metoclopramide in the release of prolactin and TSH is likely for the greater part peripheral.