THE SYNTHESIS OF IMMUNOREACTIVE PROLACTIN BY DECIDUA-CHORION

Summary

Normal term human decidua-chorion, amnion and placenta were examined for possible synthesis of prolactin (PRL) by organ culture of tissue fragments in medium M199. Before incubation, higher PRL concentrations were found in decidua-chorion (27.7±5.7 ng/mg protein; mean±SE) and amnion (19.7±6.9 ng/mg protein) than in placenta (3.1±0.5 ng/mg protein; p <0.005). Incubated deciduachorion released significantly more PRL into culture medium than did amnion or placenta. After 72 hours culture, the PRL concentration of decidua-chorion remained high (17.9±6.4 ng/mg protein); that in amnion (2.3±1.9 ng/mg protein) fell to approach that of placenta (1.4±1.0 ng/mg protein). In further studies, fragments of decidua-chorion were incubated in medium RPMI 1640 without or with puromycin (0.04 mM) or cycloheximide (0.1 mM). A decrease in medium PRL concentration was observed within four hours of adding these inhibitors of protein synthesis. At four hours, the PRL content of decidua-chorion cultured in puromycin (12.4±3 8 ng/mg protein) or cycloheximide (11.9±2.9 ng/mg protein) was lower than tissue incubated in medium alone (25.5±4.1 ng/mg protein; p <0.05). Comparable differences in tissue content and medium concentration were also seen at 24 and 72 hours. We conclude that human decidua-chorion synthesizes a protein immunologically simjlar to PRL and that this tissue may represent the principal source of amniotic fluid PRL.