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

Abstract

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 11beta-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 (P(4)), estradiol-17beta (E(2)), and prostaglandin (PG) F2alpha secretion by cultured luteal cells were investigated. Messenger RNAs of the 11-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), P(4) and PGF2alpha secretion by the cells were reduced (P < 0.05), whereas GC had no effect on E(2) 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 P(4) and PGF2alpha production from luteal cells via their specific receptors, implying GC plays some roles in regulating porcine CL function throughout the estrous cycle.

Possible Actions of Corticotropin-Releasing Hormone in Regulating Porcine Corpus Luteum Function

“…Since the inflammatory response involves the actions of cytokines, which are produced by immune cells, and since many cytokines stimulate production of PGs by the cells of target organs [2], it is possible that the CL during luteolysis is subject to inflammatory-like conditions. Our previous study demonstrated that GC inhibits P and PGF 2 secretion by cultured porcine luteal cells [21]. Therefore, this suggests that CRH directly inhibits P production in the CL and that CRH-induced GC also plays a role in suppressing the inflammatory-like process in the regressed CL in pigs.…”

“…Each pig was euthanized by electric shock as is usually done in local abattoirs. The luteal stage was classified as early (days 3-5 after ovulation), mid (days 8-11), late (days [14][15][16] or regressed (days [19][20][21] by macroscopic observation of the ovaries [1] and confirmed by measuring P concentrations in CLs (n=4/each stage). For gene expression studies, the CLs were immediately separated from the ovaries, frozen rapidly in liquid nitrogen and stored at -80C until use.…”

“…It has been shown to inhibit expression of cytokines, adhesion molecules and enzymes involved in the inflammatory process [4]. Our recent study demonstrated the presence of GC and its converting enzymes in the porcine corpus luteum (CL) and that GC inhibits steroid production from cultured luteal cells [21], suggesting that GC may regulate CL function locally in pigs.Recent studies indicate that a CRH/CRH-R system also exists outside the central nervous system. CRH and CRH-R have been identified in the human placenta [8,17], endometrium [11,12] and ovaries [3,14].…”

“…It has been shown to inhibit expression of cytokines, adhesion molecules and enzymes involved in the inflammatory process [4]. Our recent study demonstrated the presence of GC and its converting enzymes in the porcine corpus luteum (CL) and that GC inhibits steroid production from cultured luteal cells [21], suggesting that GC may regulate CL function locally in pigs.…”