Circulating nitric oxide changes throughout the menstrual cycle in healthy women and women affected by pathological hyperprolactinemia on dopamine agonist therapy.

The aim of the study was to evaluate circulating nitric oxide (NO) levels throughout ovulatory cycles in healthy women and women under long-term treatment with dopamine agonists. Fifty women (aged 32.5 +/- 1.2 years) affected by pathological hyperprolactinemia (prolactin (PRL)-secreting microadenoma, 63%; idiopathic, 19%; 'empty sella', 12%; and PRL-secreting macroadenoma, 6%) and on dopamine-agonist therapy (range 1-10 years) were studied; 37 healthy women (aged 30.4 +/- 1.4 years) served as a control group. Blood samples were collected on days 7, 14 and 21 of the menstrual cycle in order to assay NO, PRL, 17 beta-estradiol and progesterone. In all subjects, ovulatory cycles were recorded. PRL levels were comparable between the two groups and significantly rose during the luteal phase. NO levels recorded throughout the menstrual cycles of healthy controls were significantly higher than those recorded in subjects treated with dopamine-agonist; NO levels in the latter were no different from those recorded in non-treated, non-ovulatory hyperprolactinemic women. However, in both healthy controls and dopamine-agonist-treated women, NO was negatively correlated with progesterone concentration and significantly reduced on day 21. In dopamine-treated patients, NO levels did not correlate with the dose or the duration of dopamine-agonist therapy. We conclude that, in our hyperprolactinemic women on therapy, physiological NO secretion is not fully restored, despite restoration of ovulatory cycles by dopamine-agonist therapy.