Dopamine might not be involved in the pathogenesis of polycystic ovary syndrome

The possible alteration in dopamine (DA) metabolism as an etiological factor was investigated in 31 normoprolactinemic patients with typical polycystic ovary syndrome (PCOS) in comparison with 14 normal women (early follicular phase). Subjects were submitted to intravenous infusion of 4 micrograms/kg DA per minute over a period of 3 hours and blood samples were collected every 30 minutes over a period of 5 hours. Two days later subjects were submitted to intravenous infusion of 10 mg metoclopramide (MCP) as a bolus and blood samples were collected every 15 minutes over a period of 2 hours. Dopamine infusion caused a similar maximum decrease (MD) in LH levels in both the PCOS and control groups (50.9% and 47.5%, respectively). No changes in plasma LH levels were observed in either group after MCP infusion. Dopamine caused a 50.2% and 60.4% MD in prolactin (PRL) in the PCOS and control groups, respectively, the difference being statistically non-significant. Metoclopramide increased PRL levels by 1261.0% and 1832.0% in the PCOS and control groups, respectively (not significant). In a double-blind study, the PCOS patients were treated with 5 mg/day bromocriptine (n = 16) or placebo (n = 15) over a period of 3 months and evaluated in clinical and laboratory terms during and after treatment. Seven patients in each group had monthly menstrual periods, but only 1 in each group had an ovulatory cycle (progesterone greater than 5 ng/ml). During treatment, median plasma PRL levels were significantly decreased only in bromocriptine-treated patients (10.8 vs 7.3 ng/ml). The present results lead us to question whether dopamine is indeed involved in the pathogenesis of normoprolactinemic PCOS and whether bromocriptine treatment is of benefit in this type of patients.