Prolactin production during in vitro decidualization of proliferative endometrium

Decidua obtained in the late luteal phase of the human menstrual cycle has been shown to produce immunoreactive prolactin (PRL). The amount of PRL produced is a function of the extent of decidual differentiation. Further, the maintenance of decidualization and PRL production in specimens of late luteal phase in explant culture is dependent on the presence of progesterone (P). To further examine P's effect on decidualization, PRL production was monitored during P-induced decidualization of proliferative endometrium in vitro. Samples of proliferative endometrium obtained from six hysterectomy specimens were cultured in Dulbecco's modified Eagle medium in the presence of no hormones, 200 pg/ml estradiol (E2) 20 ng/ml P, and 20 ng/ml P with 200 pg/ml E2. It was found that P alone or with E2 caused PRL production and histologic decidualization. However, E2 slowed the histologic progression of P-induced decidualization on days 2 and 4 and decreased the rate of PRL production (p less than 0.01) on days 6, 8, and 10 of culture. These data indicate that P alone is capable of inducing decidualization and initiating PRL production. Further, E2 can modify the rate and/or extent of this P-mediated phenomenon.