[Synthesis of prolactin by human decidua in vitro (author's transl)]

Human decidua, chorion, amnion and placenta from 1st., 2nd. and 3rd. trimesters of gestation were investigated for synthesis and secretion of prolactin by in vitro incubation of these tissue fragments in medium 199. Prolactin content in decidua was found to be significantly higher than those in chorion, amnion or placenta at any stages of gestation. During 6 hours of incubation, decidua secreted significantly more prolactin into medium than did chorion, amnion or placenta. Amount of prolactin secreted by decidua was significantly higher than prolactin content in tissue before incubation. Decidua were also incubated in medium 199 with or without actinomycin-D (20-200 microgram/ml), puromycin (200 microgram/ml) or cycloheximide (100-200 microgram/ml) for 12 hours. Both total prolactin secretion into medium and prolactin content in tissue after incubation were significantly lower as compared to control without inhibitor. Decidua of 2nd. trimester of gestation was noted to secrete more prolactin into medium than decidua of 1st. or 3rd. trimester of gestation. In further studies, radioleucine (200 uCi) was incubated for 12 hours with decidua (10 grams) from 2nd. trimester of gestation, the incorporated radioprotein in medium or tissue was extracted, fractionated by Sephadex G-100 chromatography and by 10% SDS-polyacrylamide gel electrophoresis. Peaks of radioactivity and immunoreactive prolactin in gel slices were coincident with the peak of human pituitary prolactin (NIAMDD, hPRL, Friesen No. 1) at Kf = 0.62 (gel slice No. 31). In addition, mRNA was extracted from decidual tissue by oligo-d (T)-cellulose chromatography, which was then used for cell-free system translation study. The translation product of decidual mRNA and rabbit reticulocyte lysate was shown to be identical to human pituitary prolactin by analysis of gel electrophoresis. These results demonstrate that prolactin synthesized and secreted by human decidua is identical to human pituitary prolactin. The synthetic activity is most prominent in the decidua of 2nd. trimester of gestation.