Ovine chorionic somatomammotrophin (oCS) production by isolated cotyledon cells from sheep in early and mid gestation: auto-regulation by recombinantoCS

We report the ability of sheep placental cotyledonary cells, isolated at di fferent periods of pregnancy (40 to 90 days) to produce ovine chorionic som atomammotrophin (oCS) in in vitro culture conditions. This oCS production i ncreased gradually with stage of pregnancy. Endogenous oCS net production b y isolated placental cells was increased, in a dose-dependent manner, by ad dition of recombinant oCS (roCS). This effect was not observed after additi on of recombinant ovine growth hormone. The roCS effect was more potent on cells collected during early pregnancy. Specific immunoprecipitation of oCS revealed that roCS treatment was associated with an increased dose-depende nt incorporation of [S-35]methionine- [S-35] cysteine. These findings provi de evidence that oCS may act in a paracrine/autocrine manner to up-regulate its own production during early gestation. We suggest that this autoregula tion may be associated with morphological and functional differentiation of the trophoblast during the growth of the placenta.