Differential expression of the @entity172 receptors alpha and beta in the XXXX corpus luteum of pregnancy: regulation by prolactin and placental lactogens.

@entity172 @entity49618 @entity1184 @entity7605 @entity70608 @entity53 @entity12209 @entity51232 @entity35
@entity53 , together with PRL and placental lactogens, regulates steroidogenesis and cell @entity1184 in the @entity35 corpus luteum of pregnancy. Although binding experiments have demonstrated the presence of @entity172 -binding sites, no evidence exists as to whether the @entity35 corpus luteum of pregnancy expresses the @entity172 receptor (ER) genes. In this investigation, we have analyzed the expression of the two ER genes ( @entity7605 and @entity12209 ) (by RT-PCR and in situ hybridization) in the @entity35 corpus luteum, studied their developmental changes throughout pregnancy, and investigated the regulation of @entity7605 and @entity12209 messenger RNA (mRNA) expression by PRL and placental lactogens. The RT-PCR studies showed that both ER mRNA species ( @entity7605 and @entity12209 ) are coexpressed in the @entity35 corpus luteum during pregnancy. Whereas @entity7605 mRNA increased from early pregnancy, reached a maximum at midpregnancy, and had a remarkable decline before parturition; @entity12209 mRNA remained constant throughout pregnancy, with a significant decline at parturition. Examination of @entity7605 and @entity12209 mRNA expression at the cellular level, by in situ hybridization, showed @entity7605 expressed in both follicles and corpus luteum, with maximal expression at midpregnancy. In parallel with the RT-PCR studies, @entity12209 mRNA was similarly expressed throughout pregnancy in the corpus luteum, but it was less abundant when compared with small and growing follicles. Western blot analysis revealed two ER immunoreactive proteins in the nuclear fraction obtained from pregnant @entity35 corpus luteum: a 67-kDa moiety, highly expressed at midpregnancy but barely detectable in early and late gestation; and a 61-kDa form that remained developmentally unchanged. Hypophysectomy, performed early in pregnancy, induced a sharp decline in @entity7605 mRNA expression but a less-marked reduction in @entity12209 mRNA levels. PRL treatment reverted the inhibition induced by hypophysectomy in both receptor subtypes. When primary luteinized cells were used to test the effect of PRL, @entity35 @entity70608 , and @entity35 @entity51232 on the expression of @entity7605 and @entity12209 mRNA, all these lactogenic hormones stimulated both ER mRNA species in a dose-dependent manner. The regulation of ER mRNA expression was further evaluated in a luteal cell line, termed GG-CL, which apparently expresses only the @entity12209 mRNA species. Culture of the GG-CL cells, in the presence of PRL, resulted in a dose-related up-regulation of @entity12209 mRNA expression. In addition, PRL treatment enhanced the binding activity of GG-CL cell nuclear proteins to a classical @entity172 response element. Furthermore, in these cells, @entity53 treatment induced a dose-dependent up-regulation of the mRNA encoding @entity49618 isoform, a well-known @entity172 target gene in the corpus luteum of the pregnant @entity35 .
