Ila A. Maslar

Prolactin production by human endometrium during the normal menstrual cycle.

Prolactin (PRL) synthesis by human decidua from term pregnancies has been reported. The present study examined the tissue content and in vitro production of prolactin by decidualized and nondecidualized endometrium unassociated with pregnancy. Tissue obtained throughout the menstrual cycle was dated histologically. When proliferative endometrium (N = 16) or secretory endometrium prior to day 22 (N = 6) was examined, no PRL was detected in the tissue or medium after a 24-hour incubation at 37 degrees C in Geys buffer. Total PRL in tissue and medium measured by radioimmunoassay increased significantly from 1.2 +/- 0.3 ng/100 mg of tissue at cycle days 22 to 24 (N = 4) to 5.3 +/- 2.4 ng/100 mg of tissue at cycle days 25 to 26 (N = 7). The addition of 100 micrograms/ml of cycloheximide to the medium prevented the net increase in PRL content during incubation. It is concluded that PRL is synthesized by endometrium during the normal menstrual cycle and that the appearance and degree of synthesis and decidualization of the stroma correspond.

Denovo synthesis of prolactin by human decidua

Abstract Relatively large amounts of immunoreactive prolactin were measured in homogenates of human decidual tissue obtained immediately after delivery of normal term pregnancies. In order to study the release and possible synthesis of prolactin by this tissue, explants of decidua were incubated for 24 hours at 37°C in oxygenated Geys buffer containing 20% fetal calf serum. When cycloheximide was added to the medium in concentrations sufficient to prevent in vitro protein synthesis, 85–90% of the prolactin present in the tissue was released into the medium during the first 3 hours of incubation. No additional prolactin accumulated in either the medium or the tissue during the remainder of the incubation period. In the absence of cycloheximide, the prolactin concentration in the medium increased progressively during incubation, so that after 24 hours the total amount of hormone present in the tissue and medium was significantly greater than that in the tissue and medium prior to incubation (37.6 ± 9.6 ng/ml at 0 time vs 82.2 ± 7.7 ng/ml at 24 hours). When 3H-1-leucine (100 u Ci) was supplied during incubation, radioactive proteins were detected in the medium at 24 hr, 14–20% of which were specifically precipitated by antiserum to human pituitary prolactin. When aliquots of this medium were chromatographed on Sephadex G-100, 80–95% of the 3H-proteins precipitated by antiserum to pituitary prolactin eluted in the same position as did purified, iodinated pituitary prolactin. These data indicate that a species of prolactin which is identical to pituitary prolactin by the criteria of immunoprecipitation and gel chromatography is synthesized by human decidual tissue in vitro .

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 Ps 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 Dulbeccos 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.

Decidual production of prolactin in late gestation: Further evidence for a decidual source of amniotic fluid prolactin

The capacity of human decidual tissue to synthesize prolactin de novo throughout late gestation was investigated and correlated with the levels of prolactin (PRL) in amniotic fluid. Maximal concentrations of PRL in both amniotic fluid and samples of decidua were found prior to the thirtieth week of gestation and declined simultaneously until term. A high correlation (r = 0.90, p < 0.00005) was found when the levels of PRL in amniotic fluid and the initial (preincubation) content of PRL in decidua from the same patient were compared. A very high correlation (r = 0.96, p < 0.00005) was seen between the ability of the decidua to produce prolactin in vitro and the corresponding levels of prolactin in amniotic fluid. No significant difference in any parameter tested was noted with respect to either the sex of the fetus or the mode of delivery (p > 0.05). These data are interpreted as indicating (1) that decidual tissue varies throughout late gestation, in both its initial content of prolactin and its ability to synthesize prolactin de novo, in a manner which correlates to a high degree with variations in amniotic fluid prolactin levels and (2) that the decidual tissue is the major source of amniotic fluid prolactin.

Prolactin production by luteal phase defect endometrium

The production of prolactin (PRL) by explants of late secretory endometrium obtained during normal cycles (n = 61) and that by similar explants obtained during luteal phase deficient (n = 17) cycles was compared. The amount of prolactin produced in vitro correlated with the degree of histologic decidualization in both normal and luteal phase defect endometria. However, samples of luteal phase defect endometrium produced significantly less prolactin (p less than 0.01) than did control tissues of the same ideal menstrual dates. These data indicate that the amount of prolactin produced by late secretory endometrium in explant culture can be used as an additional criterion for the diagnosis of luteal phase defects and may also provide a method for evaluating the response of the endometrium to progesterone.

Term decidua response to estradiol and progesterone.

Immunoreactive prolactin (PRL) is produced from decidualized endometrium from the late luteal phase until the time of delivery. The induction of decidualization and the initiation of PRL production in the proliferative endometrium is dependent on progesterone (P) in vitro. This induction process is slowed by estradiol (E2). To determine whether this hormone dependency extends to term, decidua from labor and nonlabor term pregnancies was cultured in explant for response to P (100 ng/ml) and E2 (10 ng/ml) as evidenced by PRL production. On the first (n = 7) and eighth to ninth (n = 9) days of explant culture in nonlabor patients, P exposure resulted in significantly (p less than 0.01) more PRL production than in nonhormonal controls, and this increase was not inhibited by E2 at either time interval. In labor-exposed decidua, no significant response was noted to either P or E2 over 24 hours of culture. In all groups, tissue variability in PRL production was extensive. In nonlabor decidua, a significant interaction between basal PRL production and response to progesterone was noted (p less than 0.01). The role of P as an initiator and stimulator of PRL production extends to term; however, no clear effect of E2 is demonstrated. In labor-exposed decidua, this P response is eliminated. Whether this is a result of, or occurs prior to, labor is undetermined.

Stimulatory activity of serum on prolactin production by human decidua

Fetal calf serum (FCS) enhances the synthesis and secretion of prolactin (PRL) by explants of human decidua incubated in Geys balanced salt solution. In order to further characterize the factors involved in the prolactin-stimulating activity (PSA) of serum, decidua was incubated in Geys buffer alone and in buffer containing either FCS, bovine serum albumin (BSA), or human serum (HS). When buffer was supplemented with varying concentrations of FCS, ad dose-related PSA was apparent between 0.1% and 10%. The PSA of FCS was not altered by eithr heating (85degrees C for 30 minutes), boiling, or dialysis. The protein fraction of FCS, precipitated with trichloroacetic acid, redissolved in dilute NaOH, and dialyzed against Dulbeccos phosphate buffer, demonstrated PSA comparable to that of whole serum. A similar concentration of BSA added to Geys buffer did not stimulate the production of PRL by decidua. The PSA of human serum obtained from euprolactinemic men and women was not different from that of FCS. These data indicate that FCS and HS contain a substance(s) (1) which stimulates the secretion of PRL by human decidua, (2) which is very stable, being resistant to dialysis, boiling, and denaturation by trichloroacetic acid, (3) and which is most likely a large polypeptide with a molecular weight greater than 12,000 or a smaller moiety tightly bound to a protein.

The significance of lymphocytic-leukocytic infiltrates in interpreting late luteal phase endometrial biopsies

The effectiveness of the endometrial biopsy in diagnosing luteal phase defects as a cause of infertility depends upon the accurate determination of a histologic date based on the morphologic features of tissue. The criteria--edema, predecidual reaction, stromal mitosis, and lymphocytic-leukocytic infiltrate--used to interpret such biopsies were based on changes occurring in the normal ideal menstrual cycle. The present study examines the criteria used for dating endometrium as applied to endometrial biopsies for luteal phase deficiency. It was determined that one of these criteria, lymphocytic and leukocytic infiltration, correlated with subsequent onset of menses and not with the other indications of histologic maturity during the late secretory phase.