The elevation of endogenous prolactin secretion using thyrotopin releasing hormone was associated with significant increases in mammary milk production in postpartum women. More-over, a specific effect was seen on the percent fat composition which has been shown to rise as much as 228% over pretest conditions. As in the bovine, administration of high doses of estrogen is associated with mammary breast development and the sudden removal of this stimulus if accompanied by nipple stimulation is associated with non-puerperal lactation. The inhibitory effects of estrogen on the mammary cellular response to circulating prolactin has been deduced from studies in pregnant and parturient women by measuing the TRH-induced prolactin response. These studies support a relationship between prolactin and sex steroids on the initiation and maintenance of human lactation.
To gain further insight into the mechanisms of postpartum infertility, plasma gonadotropins, prolactin, estradiol, and progesterone were measured following either iv LHRH or im menopausal gonadotropins (Pergonal) to postpartum women. Plasma estradiol and progesterone rose significantly between 24-72 hours following hMG injection. The response was similar in both nursing and non-nursing women throughout the intermediate and late postpartum study interval. No gonadotropin response was observed following LHRH injection in the early puerperium. Beyond five postpartum weeks, a significantly greater response following LHRH was observed in nursing compared with non-nursing women. A subsequent and significant rise in estradiol correlated with the magnitude of the LHRH-induced increment. Basal prolactin levels in nursing women were significantly greater than in non-nursing women but were unchanged after either hMG or LHRH. We conclude that the postpartum ovary is not refractory to either direct exogenous gonadotropin stimulation or to endogenously released gonadotropins, at least as far as estrogen production is concerned. Furthermore, the difference in the pituitary response to LHRH in nursing and non-nursing women may reflect a difference in the hypothalamic-pituitary axis. Elevated prolactin secretion in response to nursing may be involved in postpartum infertility, but the specific role remaine unclear.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.