The myometrium of postmenopausal women produces prolactin in response to human chorionic gonadotropin and α-subunit in vitro

Abstract

To examine the effect of equimolar concentrations of hCG and dissociated alpha-subunit on PRL production by leiomyoma and myometrial tissue obtained from different hormonal states and to examine changes in PRL messenger RNA levels as PRL protein levels increased. Explant cultures of leiomyomas and myometrium were established and cultured for 96 hours. Tissue was studied from normal cycling women, postmenopausal women, pregnant women, and women undergoing GnRH agonist (GnRH-a) therapy. Cultured medium was collected at 24, 48, and 96 hours and assayed for PRL. In selected experiments, tissue was processed at 0 and 96 hours to analyze messenger RNA (mRNA) levels. Human chorionic gonadotropin and alpha-subunit stimulated PRL secretion in [1] explant cultures of leiomyoma and myometrium from premenopausal women, [2] cultures of tissue treated in vivo with leuprolide acetate for both leiomyoma and myometrium, and [3] myometrium obtained from postmenopausal women. Postmenopausal myometrium was significantly more responsive to stimulation. Prolactin mRNA levels were documented to increase after hormone treatment in postmenopausal myometrium. Myometrium from postmenopausal women is very responsive to hCG and alpha-subunit. There is a difference in response between tissue obtained from menopausal women and that from women undergoing GnRH-a therapy to achieve a "medical menopause" and reproductive age women. The level of endogenous gonadotropins as well as the steroid milieu may modulate myometrial PRL secretion.