Tumor Necrosis Factor (alpha)in the Bovine Oviduct During the Estrous Cycle: Messenger RNA Expression and Effect on Secretion of Prostaglandins, Endothelin-1, and Angiotensin II

Tumor necrosis factor (TNF) (alpha) an important physiological mediator of cell-to-cell communication. Recent observations suggest that TNF(alpha) is involved in the control of reproductive functions. The present study examined the role of TNF(alpha) in the secretion of factors involved in regulating smooth muscle contraction, such as prostaglandin E2 (PGE2), prostaglandin F2(alpha) (PGF2(alpha)), endothelin-1 (ET-1), and angiotensin II (Ang II), as it was in the original by the cow oviduct at different stages of the estrous cycle using an in vitro microdialysis system. Expression of mRNA for TNF(alpha) and its receptors (TNF(alpha)-R) was also evaluated. For microdialysis, the lumen of a portion (length, 10 cm) of the each oviductal segment was implanted with a dialysis capillary membrane, and TNF(alpha) (100 ng/ml) was infused for 4–8 h during a 16-h incubation period. The microdialysis system maintains cell-to-cell integrity and cell-to-cell communication, and it enables real-time observation of physiological changes in the luminal release of different substances. Concentrations of PG, ET-1, and Ang II in 4-h fractions were measured using second-antibody enzyme immunoassays. Infusion of TNF(alpha) stimulated oviductal secretion of PG, ET-1, and Ang II during the follicular and postovulatory stages, but not during the luteal stage. Expression of TNF(alpha), TNF(alpha)-R type I, and TNF(alpha)-R type II mRNA was detected in the bovine oviduct by reverse transcription-polymerase chain reaction. High expression of both TNF(alpha)R types and ligands was detected during the follicular and postovulatory stages, whereas low expression was detected during the luteal stage. The results of the present study provide, to our knowledge, the first direct evidence that TNF(alpha) stimulates PG, ET-1, and Ang II secretion and that up-regulation of the TNF(alpha) system occurs in the cow oviduct during the periovulatory period. In conclusion, the TNF(alpha) system may optimize the release of contraction-related substances and modulate local contraction to regulate the oviductal transport of the gametes and embryo.