Gonadotropin and prolactin pulsations in hyperprolactinemic women before and during bromocriptine therapy.J Clin Endocrinol Metab. 1984 Jun; 58(6):1141-7.JC
Pulsatile gonadotropin secretion and its relationship to PRL and estradiol (E2) secretion were investigated in 20 hyperprolactinemic amenorrheic women by obtaining serial blood samples for 6- to 24-h periods. Thirteen patients were restudied in the early follicular phase of the menstrual cycle (days 3-5) after ovulatory periods were established during bromocriptine therapy. In the hyperprolactinemic women, the number of LH peaks ranged from 0-12/24 h, and LH peak amplitude ranged from 0-1.7 mIU/ml. Serum E2 correlated with mean LH concentrations (P less than 0.001) and LH pulse frequency (P less than 0.05), but not with LH pulse amplitude. FSH pulsations were identified in 3 of the 20 women. There was no correlation between mean FSH concentrations and either serum E2 or PRL. There was a significant correlation between LH and FSH concentrations (P less than 0.001). During bromocriptine therapy, with comparable E2 concentrations, 5 of the 6 patients studied with blood sampling every 20 min for 24 h had a significant decrease (P less than 0.01) in the number of LH peaks per 24 h, with no change in LH peak amplitude. Mean FSH concentrations were unchanged in bromocriptine-treated patients; however, there was a significant (P less than 0.02) decrease in FSH levels during sleep. Serum PRL was normal in all bromocriptine-treated patients, but normal PRL secretory patterns were not reestablished, and there was no correlation between LH pulsations and serum PRL concentrations. We conclude that 1) hyperprolactinemic women have a heterogeneous pattern of pulsatile gonadotropin secretion; 2) serum E2 correlates with LH pulse frequency but not pulse amplitude; 3) LH pulsations and PRL pulsations are asynchronous in hyperprolactinemic women before and during bromocriptine therapy; and 4) normal PRL secretory patterns are not required for ovulatory function in hyperprolactinemic women treated with bromocriptine.