Effects of tumor necrosis factor-alpha on secretion of prostaglandins E-2 and F-2 alpha in bovine endometrium throughout the estrous cycle

To determine the physiological significance of tumor necrosis factor-alpha (TNF alpha) in the regulation of endometrial prostaglandin (PG) release in cattle, we investigated the effects of TNF alpha on the secretion of PGE(2) and PGF(2 alpha) by bovine endometrium during the estrous cycle. Bovine ut eri were classified into six stages (estrus: Day 0, early luteal I: Days 2 to 3, early luteal II: Days 5 to 6, mid-luteal: Days 8 to 12, late luteal: Days 15 to 17 and follicular: Days 19 to 21). After 1 h of pre-incubation, endometrial tissues (20 to 30 mg) were exposed to 0 or 0.6 nM TNF alpha for 4 h. The PGE(2) concentrations in the medium were higher in the luteal sta ges than in the follicular stage and in estrus. In contrast, PGF(2 alpha) c oncentrations were higher in the follicular stage and in estrus than in the luteal stages. The ratio of the basal concentrations of PGE(2) and PGF(2 a lpha), (PGE(2)/PGF(2 alpha) ratio) was higher in the luteal stages than in the follicular stage and in estrus. Although TNF alpha stimulated both PGE( 2) and PGF(2 alpha) secretion during the entire period of the estrous cycle , the level of stimulation of TNF alpha on PGE(2) output by the bovine endo metrium does not Show the same cyclical changes as that shown on PGF(2 alph a) output. The stimulation of TNFa resulted in a decrease in the PGE(2)/PGF (2 alpha) ratio only in the late luteal stage. Furthermore, TNF alpha stimu lated PGE(2) secretion in stromal, but not epithelial cells. The overall results suggest that TNF alpha is a potent regulator of endomet rial PGE(2) secretion as well as PGF(2 alpha) secretion during the entire p eriod of estrous cycle, and that TNFa plays different roles in the regulati on of secretory function of bovine endometrium at different phases of the e strous cycle. (C) 2001 by Elsevier Science Inc.