The Decline Of Pregnancy Rate And Abnormal Responsiveness Of Steroid Hormones In Aging Mice

Aging is characterized by a progressive decline in multiple physiological functions with increasing age.Aging is also a threat to reproductive health in humans.In recent years,the age at which a woman has first pregnancy has been postponed with the development and progress of the society,and infertility increases in older women.Reproductive capacity in animals and women declines with increasing age.Although a key aspect of reproductive aging is the decrease in ovary function,the rate of implantation failure is also high after blastocysts from young donors are transferred to older women.Therefore,uterus may be the cause of implantation failure.What happens during uterine aging remains unclear.Therefore,it is important to re veal the mechanism underlying uterine aging.In order to reveal the association between aging and female reproduction,2 and 12 months old female CD1 mice were housed in a SPF facility and were mated naturally with fertile males(3-to 5-months old)to induce pregnancy(one male for one female),respectively.Uteri were collected on days 5 and 8 to record the numbers of implantation sites.The results show that the pregnancy rate and implantation number significantly declined in 12 months old mice.On day 4 of pregnancy,Muc1 and PR level in 12 months old mice was significantly higher than that in 2 months old mice,Hand2 was significantly lower.Additionally,the steroid hormone-responsiveness in ovariectomized mouse uteri was compared between 2 and 12 months old mice.When ovariectomized mice are treated with progesterone,there are more genes showing down-regulation pattern,including PR,Ltf,Ihh,Lif,Hand2 in 12 months old mice.In conclusion,our data showed that implantation rate and number of implantation sites decline in 12 months old mice.In ovariectomized mice,there is an abnormal responsiveness of progesterone(P4)and progesterone(E2)for some implantation-related genes.The abnormal responsiveness of steroid hormones in 12 months old mice may be the cause of low pregnancy.The results could help us understand the effects of aging on female reproductive,and provide the mechanism underlying for the female reproductive aging.