Production of prostaglandin F-2 alpha by cultured bovine endometrial cellsin response to tumor necrosis factor alpha: Cell type specificity and intracellular mechanisms

Tumor necrosis factor alpha (TNF alpha) has been shown to be a potent stimu lator of prostaglandin (PG) F-2 alpha secretion in the bovine endometrium. The aims of the present study were to determine the cell types in the endom etrium (epithelial or stromal cells) responsible for the secretion of PGF(2 alpha) in response to TNF alpha, and the intracellular mechanisms of TNFa action. Cultured bovine epithelial and stromal cells were exposed to TNF al pha (0.006-6 nM) or oxytocin (100 nM) for 4 h. TNF alpha resulted in a dose -dependent increase of PGF(2 alpha) production in the stromal cells (P < 0. 001) but not in the epithelial cells. On the other hand, oxytocin stimulate d PGF(2 alpha) output in the epithelial cells but not in the stromal cells. When the stromal cells were incubated for 24 h with TNF alpha and inhibito rs of phospholipase (PL) C or PLA(2) only PLA(2) inhibitor completely stopp ed the actions of TNF alpha (P < 0.001). When the stromal cells were expose d to TNF alpha and arachidonic acid, the action of TNF alpha was augmented (P < 0.001). When the stromal cells were incubated for 24 h with a nitric o xide (NO) donor (S-NAP), S-NAP stimulated the PGF(2 alpha) production dose- dependently. Although an NO synthase (NOS) inhibitor (L-NAME) reduced TNF a lpha-stimulated PGF(2 alpha) production, an inhibitor of phosphodiesterase augmented the actions of TNF alpha and S-NAP (P < 0.05). The overall result s indicate that the target of TNF alpha for stimulation of PGF(2 alpha) pro duction in cattle is the endometrial stromal cells, and that the actions of TNF alpha are mediated via the activation of PLA, and arachidonic acid con version. Moreover, TNF alpha may exert a stimulatory effect on PGF(2 alpha) production via the induction of NOS and the subsequent NO-cGMP formation.