Expressions of estrogen receptors in the bovine corpus luteum: Cyclic changes and effects of prostaglandin F2alpha and cytokines

• Published in: The Journal of reproduction and development 2007-10, Vol.53 (5), p.1059-1068
• Main Authors: Shibaya, M.(Okayama Univ. (Japan)), Matsuda, A, Hojo, T, Acosta, T.J, Okuda, K
• Format: Article
• Language: English
• Subjects: Animals; Cattle; CICLO ESTRAL; CITOQUINAS; CORPS JAUNE; CORPUS LUTEUM; Corpus Luteum - drug effects; Corpus Luteum - metabolism; COWS; CUERPO LUTEO; CYCLE OESTRAL; CYTOKINE; CYTOKINES; Cytokines - metabolism; Cytokines - pharmacology; Dinoprost - metabolism; Dinoprost - pharmacology; Estrogen Receptor alpha - genetics; Estrogen Receptor alpha - metabolism; Estrogen Receptor beta - genetics; Estrogen Receptor beta - metabolism; ESTROGENOS; Female; HORMONE RECEPTORS; Interferon-gamma - pharmacology; Luteal Phase - drug effects; Luteal Phase - metabolism; OESTROGENE; OESTROGENS; OESTROUS CYCLE; PCR; PROSTAGLANDINAS; PROSTAGLANDINE; PROSTAGLANDINS; RECEPTEUR D'HORMONE; RECEPTORES DE HORMONAS; RNA, Messenger - metabolism; Tumor Necrosis Factor-alpha - pharmacology; VACA; VACHE
• ISSN: 0916-8818; 1348-4400
• DOI: 10.1262/jrd.19065

Estrogen (E) exerts its function by binding to two intracellular estrogen receptors, ERalph and ERbeta. Although ERs have been reported to be expressed in the bovine corpus luteum (CL), the mechanisms that control ER expression in the bovine CL are not fully understood. To determine the possible regulatory mechanisms of ERalph and ERbeta that meditate distinct E functions, we examined 1) the changes in the protein expressions of ERs in the CL throughout the luteal phase and 2) the effects of prostaglandin (PG) F2alpha, tumor necrosis factor-alpha (TNFalpha) and interferon-gamma (IFNgamma) on the expressions of ERs in cultured bovine luteal cells. Western blot analyses revealed that ERalph and ERbeta proteins were expressed throughout the luteal phase. The ERalpha protein level was high at the early luteal (Days 2-3 after ovulation) and mid-1uteal stages (Days 8-12) and was extremely low at the regressed luteal stage (Days 19-21). The ERbeta protein level increased from the early to developing luteal stage, remained at the same level at the mid-luteal stage and decreased thereafter. The ratio of ERbeta to ERalph was higher in the regressed stage than in the other stages. Luteal cells obtained from mid-stage CLs (Days 8-12) were incubated with PGF2alpha (0.01-1 microM), TNFalpha (0.0145-1.45 nM) or IFNgamma (0.0125-1.25 nM) for 24 h. PGF2alpha and TNFalpha inhibited ERalpha and ERbeta mRNA expressions. IFNgamma suppressed ERbeta mRNA expression but did not affect the expression of ERalpha mRNA. However, the ERalpha and ERbeta protein levels were not affected by any of the above treatments. These data indicate that PGF2alpha, TNFalpha and IFNgamma regulate ERalpha and ERbeta mRNA expressions in bovine luteal cells. Moreover, the changes in the ERbeta/ERalpha ratio throughout the luteal phase suggest that ERalph is associated with luteal maintenance. Therefore, a dramatic decrease in ERalph at the regressed luteal stage could result in progression of structural luteolysis in the bovine CL.