Production of prostaglandin f(2alpha) by cultured bovine endometrial cells in response to tumor necrosis factor alpha: cell type specificity and intracellular mechanisms

Tumor necrosis factor alpha (TNFalpha) has been shown to be a potent stimulator of prostaglandin (PG) F(2alpha) secretion in the bovine endometrium. The aims of the present study were to determine the cell types in the endometrium (epithelial or stromal cells) responsible for the secretion of PGF(2alpha) in response to TNFalpha, and the intracellular mechanisms of TNFalpha action. Cultured bovine epithelial and stromal cells were exposed to TNFalpha (0.006-6 nM) or oxytocin (100 nM) for 4 h. TNFalpha resulted in a dose-dependent increase of PGF(2alpha) production in the stromal cells (P < 0.001) but not in the epithelial cells. On the other hand, oxytocin stimulated PGF(2alpha) output in the epithelial cells but not in the stromal cells. When the stromal cells were incubated for 24 h with TNFalpha and inhibitors of phospholipase (PL) C or PLA(2), only PLA(2) inhibitor completely stopped the actions of TNFalpha (P < 0.001). When the stromal cells were exposed to TNFalpha and arachidonic acid, the action of TNFalpha was augmented (P < 0.001). When the stromal cells were incubated for 24 h with a nitric oxide (NO) donor (S-NAP), S-NAP stimulated the PGF(2alpha) production dose-dependently. Although an NO synthase (NOS) inhibitor (L-NAME) reduced TNFalpha-stimulated PGF(2alpha) production, an inhibitor of phosphodiesterase augmented the actions of TNFalpha and S-NAP (P < 0. 05). The overall results indicate that the target of TNFalpha for stimulation of PGF(2alpha) production in cattle is the endometrial stromal cells, and that the actions of TNFalpha are mediated via the activation of PLA(2) and arachidonic acid conversion. Moreover, TNFalpha may exert a stimulatory effect on PGF(2alpha) production via the induction of NOS and the subsequent NO-cGMP formation.