Abstract: Objective To investigate the expression and distribution of lysophosphatidic acid receptor 3 (LPA3) during the period of mouse embryo implantation and the effect of estrogen and progesterone and RU486 on murine endometrial LPA3 expression. Methods Immunohistochemistry was employed to observe and analyze the expression and distribution of LPA3 protein in the uterine endometrium during the 1~6th pregnancy day (d1~6). Ovariectomized mice were randomly divided into control and treatment groups,estrogen, progesterone and RU486 was given to ovariectomized mice.The expression of LPA3 mRNA and protein were detected by RT-PCR and Western blotting. Results LPA3 protein was expressed in the endometrium of 1~6th pregnancy day . The LPA3 protein level in the uteri increased on d3 , peaking around d4., then returned to the basal levels on d5 and d6 . LPA3 mRNA and protein expression remained at a low level in ovariectomized mice. Progesterone up-regulated LPA3 mRNA and protein. Estrogen counteracted the effect of progesterone. RU486 inhibited the effect of progestin. Conclusions LPA3 may participate in the period of mouse embryo implantation. Progesterone and estrogen cooperatively regulate LPA3 expression, thereby contributing to the receptivity of uteri during early pregnancy.

Key words: Estrogen, Progesterone, Endometrium, LPA3, Murine