Effects of a dopamine antagonist (metoclopramide) on the release of the adenohypophyseal hormones in amenorrhoeic patients with and without hyperprolactinaemia

To obtain insight into the role of endogenous dopamine (DA) on the adenohypophyseal hormones release in amenorrhoeic women, responses of the adenohypophyseal hormones to a DA antagonist, metoclopramide (MCP), were evaluated in 4 normal women, in 9 normoprolactinaemic-amenorrhoeic patients, and in 7 hyperprolactinaemic-amenorrhoeic patients. The hyperprolactinaemic-amenorrhoeic patients were, in the majority, without a demonstrable microadenoma. Maximal net increase of prolactin (Prl) after MCP administration were lower (P less than 0.01) in hyperprolactinaemic patients compared with those seen in normal women or in normoprolactinaemic-amenorrhoeic patients. Administration of MCP resulted in significant elevation in serum FSH, LH and TSH in hyperprolactinaemic patients, but neither in normal women nor in normoprolactinaemic-amenorrhoeic patients. These findings suggest an increased dopaminergic inhibition of the release of TSH as well as FSH and LH in hyperprolactinaemic-amenorrhoeic patients.