绵羊妊娠识别、建立和维持的信号系统

Signal System for Recognition and Establishment of Pregnancy in Sheep

妊娠的建立和维持归因于胚体的信号和黄体对孕酮的产生,在反刍动物,胚体滋养层分泌的激素抑制子宫内膜产生前列腺素PGF2α。在发情周期的绵羊,孕酮下调子宫内膜腔上皮和子宫腺上皮孕酮受体基因的表达,并伴随着上皮雌激素受体和催产素受体的增加。在催产素的作用下,子宫开始分泌溶黄体作用的前列腺素F2α。在妊娠绵羊,孕体滋养层产生的干扰素可作用于子宫内膜而直接抑制雌激素受体基因和催产素受体基因的转录。孕酮、干扰素、胎盘催乳素和生殖激素共同组成了一个"作用网络"来调节子宫的功能分化和子宫腺的形态发生,从而维持绵羊妊娠。本文综述了绵羊妊娠识别、建立和维持的信号系统。

Establishment and maintenance of pregnancy results from signaling by the conceptus and progesterone produced by the corpus luteum. In ruminants, hormones from the trophoblast are antiluteo- lyric in that they act on the endometrium to prevent uterine release of luteolytic prostaglandin F2 alpha. In cyclic sheep, progesterone autoregulate negatively the expression of the progesterone receptor gene in the endometrial luminal and superficial glandular epithelium. And loss of the PR is closely followed by increa- ses in epithelial estrogen receptors and then oxytocin receptors , allowing oxytocin to induce uterine release of luteolytic PGF. In pregnant sheep, the conceptus trophoblast produces interferon tau that acts on the endometrium to inhibit transcription of the ER alpha gene directly and the OTR gene indirectly to cancel development of the endometrial luteolytie mechanism. Progesterone, IFN tau, placental lactogen and growth hormone comprise a hormonal regulation system that regulates endometrial gland morphogenesis and terminal differentiated function to maintain pregnancy in sheep. This review summarizes current infor- mation of conceptus signals for establishment and maintenance of pregnancy in sheep.