Objectives: 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.
Design: 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.
Results: 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.
Conclusion: 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.