Transportation of the cow and other procedures associated with harvesting the tissues caused a great deal of disturbance and stress for the parturient cows. Both conditions are known to interrupt the process of parturition in various species and references therein), and inhibit the release of OT. Because of its short half-life, COX-2 mRNA was probably no longer detectable when the samples from the cows in labor were collected. We were not aware of how critical this aspect was at the time experiment 1 was conducted. In the present study, a pharmacologic dose of OT was intentionally used to assure detection of the putative effect on COX-2 expression; amounts released in response to physiological stimuli are generally considerably smaller, even at parturition. buy birth control online
Epithelial cells of cervical mucosa express both the OTR gene and COX-2 mRNA. We have recently shown that OT induces PGE2 release from the cervical mucosa in estrous cows in vivo. The concentrations of OTR in cervical mucosa are very low during pregnancy, but they increase at term and reach twice the levels in estrous cows during parturition. According to the results of the present study, cervical COX-2 mRNA levels were significantly increased at parturition. The results obtained in cervical tissue in vitro and in estrous cows in vivo support the assumption that the increase may be induced by endogenous OT resulting in release of PGE2 from the parturient cervix. Macrophages that invade the cervix in other species around the time of parturition may also be present in the bovine cervix; when activated, macrophages secrete cytokines that induce COX-2 gene expression. Moreover, cooperation between multiple ligands that activate COX-2 transcription may possibly be required for optimal functioning, as suggested by Darnell.