Uterine Expression of Prostaglandin H2 Synthase in Late Pregnancy and during Parturition in Prostaglandin F Receptor-Deficient Mice

K Tsuboi, Y Sugimoto, A Iwane, K Yamamoto… - …, 2000 - academic.oup.com
K Tsuboi, Y Sugimoto, A Iwane, K Yamamoto, S Yamamoto, A Ichikawa
Endocrinology, 2000academic.oup.com
PG production in uterine tissues is important for many physiological processes in late
pregnancy, including parturition. We examined the expression of the PGH2 synthases,
cyclooxygenase-1 (COX-1) and COX-2, in uterine tissues during late pregnancy, using PGF
receptor-deficient (FP−/−) mice. Female FP−/− mice are unable to deliver normal fetuses at
term, as they do not undergo luteolysis necessary for parturition. In wild-type mice, COX-1
messenger RNA (mRNA) was expressed in the endometrial epithelium, myometrium, and …
Abstract
PG production in uterine tissues is important for many physiological processes in late pregnancy, including parturition. We examined the expression of the PGH2 synthases, cyclooxygenase-1 (COX-1) and COX-2, in uterine tissues during late pregnancy, using PGF receptor-deficient (FP−/−) mice. Female FP−/− mice are unable to deliver normal fetuses at term, as they do not undergo luteolysis necessary for parturition. In wild-type mice, COX-1 messenger RNA (mRNA) was expressed in the endometrial epithelium, myometrium, and decidua throughout late pregnancy. The expression of COX-1 mRNA in the endometrial epithelium and myometrium decreased both in wild-type mice undergoing natural parturition and in FP−/− mice undergoing ovariectomy-induced parturition, but expression of COX-1 mRNA was enhanced in FP−/− mice at the expected term. In wild-type mice, COX-2 mRNA was not expressed in the myometrium before parturition, but was markedly induced during parturition. This induction of COX-2 was absent in FP−/− mice at the expected term, but was found during ovariectomy-induced parturition in these mice. Expression of COX-2 proteins was confirmed by immunohistochemical analysis. Thus, in uterine tissues, myometrial expression of COX-2 is closely associated with the occurrence of parturition, but uterine expression of COX-1 is induced much earlier and kept at a high level until parturition occurs. These results suggest that COX-1-derived PGs are responsible for the induction of luteolysis, and that COX-2-derived PGs play a role in the final pathway of parturition.
Oxford University Press