During bovine pregnancy, secretion of estrogen and progesterone increases markedly, potentially leading to induction of COX-2 mRNA expression and PG release. Indeed, from Day 50 onward, OT elicits release of PGF2a in pregnant cows in increasing amounts as gestational age advances. PGF2a is luteolytic in cows; therefore increased production of PGF2a could be detrimental for the maintenance of pregnancy. The purpose of this study was to explore this apparent paradox and determine COX-2 gene expression in various bovine uterine tissues during the second half of gestation and parturition. buy birth control online
We have reported previously that a characteristic feature of OT-induced release of PGF2a in pregnant cows is the long duration of the response, which continues beyond the time during which any OT remains in the circulation or occupies endometrial oxytocin receptors (OTR). The cOx enzyme self-destructs during activity; therefore the long duration of OT-induced PGF2a release suggests continuous synthesis of the COX enzyme under the influence of OT. Another purpose was therefore to test the hypothesis that OT-induced PG synthesis is associated with transcription of COX-2 gene.