Influence of circulating prolactin increased by a psychotropic drug on gonadotrophin and progesterone secretion

The purpose of the present communication is to report on the effects of high levels of circulating prolactin on gonadotropin and progesterone secretion during the luteal phase of the menstrual cycle. Purified human prolactin not being available, endogenous prolactin was increased in six normal cycling women by daily oral administration of 150 mg sulpiride starting at midcycle. Blood samples were collected daily during a control cycle and during the cycle under treatment. Serum luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin were measured by radioimmunoassay methods. Prolactin results were expressed in terms of a laboratory standard: 1.0 unit (U) is the amount of immunoreactive prolactin contained in 1.0 ml of a pool of sera rich in prolactin. Serum progesterone was measured by competitive protein binding. All control cycles were ovulatory. The length of the luteal phase ranged from 14 to 15 days. In all cycles under treatment, there was a significant rise (p < 0.001) in serum prolactin starting the day of sulpiride administration and sustained during the entire luteal phase: the mean serum prolactin was 790 mU/ml as compared to 120 mU/ml during the luteal phase of the control cycles. Two cases showed no LH surge and no rise in progesterone secretion. In three out of the other four cases, the LH peaks occurred under treatment; they were lower than in the corresponding control cycles. In the four ovulatory cycles, the length of the luteal phase ranged from 11 to 14 days and was shortened by 1 to 4 days. During the luteal phase, the mean levels of serum LH (2.5 mIU/ml), FSH (5.0 mIU/ml) and progesterone (0.009 μg/ml) were significantly lower (p < 0.001) than those of the control cycles (LH = 7.4 mIU/ml; FSH = 10.0 mIU/ml; progesterone = 0.012 μg/ml).SCOPUS: NotDefined.j