Changes in expression of 11β-hydroxysteroid dehydrogenase type-1, type-2 and glucocorticoid receptor mRNAs in porcine corpus luteum during the estrous cycle

The objective of the present study was to determine whether glucocorticoid (GC) and its receptor (GC-R) are expressed in the porcine corpus luteum (CL), and whether GC influences porcine luteal hormone production. The gene expressions of 11β-hydroxysteroid dehydrogenase type 1 (11-HSD1), type 2 (11-HSD2), GC-R, and the concentrations of GC were determined in the CL of Chinese Meishan pigs during the estrous cycle. Moreover, the effects of GC on progesterone (P₄), estradiol-17β (E₂), and prostaglandin (PG) F2α secretion by cultured luteal cells were investigated. Messenger RNAs of the H-HSD1, 11-HSD2, and GC-R were clearly expressed in the CL throughout the estrous cycle. The 11-HSD1 mRNA level in the CL was higher at the regressed stage than at the other stages (P < 0.05), whereas 11-HSD2 mRNA was lower at the regressed stage than at the other stages (P < 0.05). GC-R mRNA level was higher at the regressed stages than at the other stages (P < 0.01). Concentrations of GC were lower in the regressed CL than in the other stages (P < 0.01). When the cultured luteal cells obtained from mid-stage CL (Days 8-11) were exposed to GC (50-5,000 ng/ml), P₄ and PGF2α secretion by the cells were reduced (P < 0.05), whereas GC had no effect on E₂ secretion by the cells. The overall results suggest that GC is regulated locally by 11-HSD1 and 11-HSD2 in the porcine CL. GC inhibits P₄ and PGF2α production from luteal cells via their specific receptors, implying GC plays some roles in regulating porcine CL function throughout the estrous cycle.