Acute effects of L-dopa and bromocriptine on serum PRL, LH and FSH levels in patients with hyperprolactinemic and normoprolactinemic polycystic ovary syndrome.

We have investigated the importance of the dopaminergic control of gonadotropin secretion by studying LH, FSH and PRL responses to L-dopa and bromocriptine in patients with polycystic ovary syndrome (PCOS). Both L-dopa and bromocriptine administration were followed by a statistically significant decrease in LH in the hyperprolactinemic PCO patients (compared to the normoprolactinemic subgroup - p less than 0.01 and control group - p less than 0.05); the decline was proportional to the basal level of LH. A significant positive correlation between basal LH levels and maximum net decrease of LH was observed after administration of both agents (p less than 0.01). Although both subgroups of PCO patients showed a similar decrease in PRL levels it was statistically significant only in the normoprolactinemic patients (p less than 0.01). Prolactin sensitivity to the inhibitory effect of bromocriptine and L-dopa showed a significant correlation with the basal PRL level (p less than 0.01). The response of serum FSH was variable and not significant. These results suggest that a reduction of an inhibitory influence of hypothalamic dopamine might be a cause of inappropriately elevated LH and PRL levels found in patients with polycystic ovary syndrome and hyperprolactinemia.