Bromocriptine effects on plasma luteinizing hormone and its responses to gonadotropin-releasing hormone in normal men

Secretory changes in plasma pituitary luteinizing hormone (LH) after administration of a dopaminergic drug were studied in five normal men. Each subject received orally 5 mg of bromocriptine (Brc) daily for 8 weeks. Each received gonadotropin-releasing hormone (GnRH) stimulation tests at the beginning (control), and at 2, 4, 6, and 8 weeks after initiation of Brc treatment. We referred the basal plasma LH and a ratio of maximally GnRH-responded plasma LH to its basal level (R-Max) as indicators of secretory alterations of the LH. Mean basal levels of plasma LH in the five subjects at the beginning and those of R-Max were 3.4 +/- 2.3 (SD) mIU/mL and 8.5 +/- 2.9 units, respectively. Statistically, both the mean values of plasma LH and R-Max during the control period did not differ significantly from those obtained after Brc treatment, although mean basal levels of plasma prolactin during the control period (15.6 +/- 4.6 ng/mL) decreased significantly (p < 0.05) after initiation of treatment. A low dose of Brc administered to normal men for 8 weeks does not significantly influence pituitary secretion of LH.