THE SYNTHESIS OF IMMUNOREACTIVE PROLACTIN BY DECIDUA‐CHORION

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Abstract
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.