Tumor necrosis factor α 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 is an important physiological mediator of cell-to-cell communication. Recent observations suggest that TNFalpha is involved in the control of reproductive functions. The present study examined the role of TNFalpha in the secretion of factors involved in regulating smooth muscle contraction, such as prostaglandin E-2 (PGE(2)), prostaglandin F-2alpha (PGF(2alpha)), endothelin-1 (ET-1), and angiotensin 11 (Ang 11), 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 TNFalpha and its receptors (TNFalpha-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 TNFalpha (100 ng/ml) was infused for 48 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 PC, ET-1, and Ang 11 in 4-h fractions were measured using second-antibody enzyme immunoassays. Infusion of TNFalpha stimulated oviductal secretion of PC, ET-1, and Ang 11 during the follicular and postovulatory stages, but not during the luteal stage. Expression of TNFalpha, TNFalpha-R type 1, and TNFalpha-R type 11 mRNA was detected in the bovine oviduct by reverse transcription-polymerase chain reaction. High expression of both TNFalphaR 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 TNFalpha stimulates PC, ET-1, and Ang 11 secretion and that up-regulation of the TNFalpha system occurs in the cow oviduct during the periovulatory period. In conclusion, the TNFalpha system may optimize the release of contraction-related substances and modulate local contraction to regulate the oviductal transport of the gametes and embryo.