Kawamata Masaki, Yoshida Masahide, Sugimoto Yukihiko, Kimura Tadashi, Tonomura Yutaka, Takayanagi Yuki, Yanagisawa Teruyuki, Nishimori Katsuhiko
Department of Molecular Biology, Graduate School of Agriculture, Tohoku University, Sendai, Miyagi 981-8555, Japan.
Mol Cell Endocrinol. 2008 Feb 13;283(1-2):32-7. doi: 10.1016/j.mce.2007.10.012. Epub 2007 Nov 4.
The dramatic increase of oxytocin (OT) receptor (OTR) in the myometrium as well as circulating progesterone withdrawal has been thought to be the most important factor in the induction and accomplishment of parturition since delivery fails in prostaglandin F2alpha receptor (FP) knockout (FP KO) mice. The expression levels of OTR mRNA/protein were not dramatically increased in the near-term uteri of FP KO mice. However, OT-induced myometrial contractions and the concentration-response curves in FP KO in vitro were almost similar to those in wild-type (WT) mice. OT-infusion (0.3 U/day) enabled FP KO mice to experience successful delivery, and furthermore the duration until the onset was hastened by a higher dose of OT (3 U/day). The plasma progesterone levels of FP KO females were maintained at high levels, but decreased during labor by OT-infusion (3 U/day). These results suggest that OT has potentials to induce strong myometrial contractions in uterus with low expression levels of OTR and luteolysis in ovary, which enabled FP KO females to undergo successful delivery.
自从前列腺素F2α受体（FP）基因敲除（FP KO）小鼠分娩失败以来，子宫肌层中催产素（OT）受体（OTR）的急剧增加以及循环孕酮的撤退被认为是诱导和完成分娩的最重要因素。在FP KO小鼠的近足月子宫中，OTR mRNA/蛋白的表达水平并未显著增加。然而，OT诱导的子宫肌层收缩以及FP KO体外的浓度-反应曲线与野生型（WT）小鼠几乎相似。OT输注（0.3 U/天）使FP KO小鼠能够成功分娩，此外，更高剂量的OT（3 U/天）可加快分娩开始的持续时间。FP KO雌性小鼠的血浆孕酮水平维持在高水平，但在分娩期间通过OT输注（3 U/天）而降低。这些结果表明，OT有潜力在OTR表达水平低的子宫中诱导强烈的子宫肌层收缩，并在卵巢中诱导黄体溶解，从而使FP KO雌性小鼠能够成功分娩。
