Expression And Hormonal Regulation Of Prostaglandin F_2a Receptor Gene And Cyclooxygenase In The Ovary And Uterus Of Mouse And Rat

Prostaglandins(PGs) are a group of derivatives of C20 carboxylic acid and exist in various tissues as intracellular signaling molecules. PGs act through their corresponding receptors which are all trans-membrane protein coupled with G- protein. Cyelooxygenase(COX) is the key enzyme for PG synthesis. PGs and their receptors act as important and versatile mediators in mammalian reproduction, such as ovulation. luteolysis, implantation and parturation. The goal of this experiment was to study the expression mode of FP gene and COX in murine female reproductive system, the effects of PG on the expression of FP gene and the relationship between uterus-derived PG and luteolysis. In this experiment the expression and hormonal regulation of PGF receptor gene in the ovary of mouse and rat were studied using in situ hybridization. The expression and hormonal regulation of cyclooxygenase in the rat uterus were also studied by immunohistochemisliy. FP mRNA was expressed in the luteal cells of mouse and rat ovary during estrus cycle and pregnancy. In the mouse at prepuberty stage, FP receptor gene was expressed in luteal cells after ovulation induced by hCG. The expression of FP mRNA reached its peak 5 days after hCG injection. PGF2a has an effect of positive feedback on the expression of its own receptor gene. PGF~ analog cloprostenal stimulated the expression of FP receptor gene in the mouse luteal cells. The inhibitors of PG biosynthesis, such as diclofenac and indomethacin, down-regulated the expression of FP mRNA in the mouse luteal cells. COX-l and COX-2 were expressed in a time- and cell-specific manner in the rat endometrium during early pregnancy. COX-l was expressed in the luminal epithelium during days 4--S of pregnancy. COX-2 protein was highly expressed in the subepithelial region of primary decidualization zone just after the onset of implantation. COX-l was expressed constituctively in the rat endometriwn after ovariectomy. Its expression was stimulated by progesterone, but was inhibited by estrogen in the luminal epithelium, Estrogen could stimulate the expression of COX- I in the progesterone-primed luminal epithelium. The expression of COX-2 was not detected in the uterus of ovariectomized rat. A single injection of estrogen or progesterone had no effect on the expression of COX-2, but estrogen stimulated the expression of COX-2 in the progesterone primed luniinal epithelium. In conclusion, the expression of COX in rat uterus was highly synchronic with implantation in a temporal and spatial manner. This phenomenon may imply that the function of COX in uterus was to regulate implantation. POSTGRADUATE: Fan Heng-Yu MAJOR: Animal Histology and Embryology SUPERVISOR: Professor Yang Zeng-Ming...