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

The objective of the present study was to determine whether corticotropin-releasing hormone (CRH) influences porcine corpus luteum function. The gene expressions of CRH receptors (CRH-R) were determined in the CLs of Chinese Meishan pigs during the estrous cycle. The effects of CRH on progesterone (P), estradiol-17β (E) and prostaglandin (PG) F₂_α secretion by cultured luteal cells were also investigated. Messenger RNAs of the <i>CRH-R</i> were clearly expressed in the CL throughout the estrous cycle, and the mRNA level was higher at the regressed stage than at the other stages (P<0.05). When the cultured luteal cells obtained from the mid-luteal stage CL (days 8-11) were exposed to CRH (50-5000 <i>n</i>g/m<i>l</i>), P secretion by the cells was significantly reduced at the highest dose (P<0.05), whereas CRH had no effect on E and PGF₂_α secretion by the cells. The overall results suggest that CRH inhibits local P production from luteal cells via its specific CRH-R, implying that CRH plays some roles in regulating porcine CL function during the estrous cycle, especially in the period of luteolysis.<br>