Abstract
Cortisol (Cr), the most important glucocorticoid (GC), is well known to suppress uterine prostaglandin F2α (PGF) production. However, the details of the regulatory mechanisms controlling the cyclic changes in endometrial PGF production remain unclear. Here we investigated the expression of the GC receptor (GC-Rα), the actions of cortisol throughout the estrous cycle and the regulatory mechanism of GC-Rα in the bovine endometrium. The levels of GC-Rα protein were greater at the mid-luteal stage (Days 8-12) than at the other stages. Cr more strongly suppressed PGF production at the mid-luteal stage than at the follicular stage. GC-Rα expression was increased by progesterone (P4) but decreased by estradiol-17β (E2) in cultured endometrial stromal cells. The overall results suggest that ovarian steroid hormones control the cyclic changes in endometrial PGF production by regulating GC-Rα expression in bovine endometrial stromal cells.