Study On The Role Of Hypoxia Inducible Factor-1αin Ovary Aging With New Physiological Ovary Aging Mouse Model

Background and ObjectivesIt has been paid more attention on the essence of aging and how to resist aging with coming into aging society. As the perimenopausal symptoms and age-related diseases caused by the decline of ovary endocrine function have affected women's healthy and life quality seriously, study on the mechanism and target to resist ovary aging comes first. Ovary aging is a long progress with complicated regulation and involved both of the quantity and quality of follicle declining. We combined repeated superovulation with ozone inhalation to establish a mouse model to accelerate the progress of ovary aging and used some age-related and reproductive endocrinology parameter to evaluate the model. Then we investigated the expression of hypoxia inducible factor-1αin different developmental stages of the follicles, the antral follicle with increasing age and different treatment group in our mouse model and analyzed the significance.MethodsSequentially administrating pregnant mare serum gonadotropin, human chorionic gonadotropin, and prostaglandin F2a and exposing to ozone were used to induce primordial follicle pool decline and oxidative damage. Realtime-PCR and immunohistochemistry were used to test the expression pattern of target gene. Electron microscopy was used to observe the morphology of follicle. Enzyme linked immunosorbent assay was used to test the serum hormone level. Fertility test was used to reflect the reproductive ability. Results(1)10 times repeated superovulation decreased the expression of AMH and ratio of primordial follicle. The concentrations of estrogen and progesterone decreased with lipid drop in GC declining. The total numbers decreased and labor interval was prolonged.(2) Ozone inhalation increased the expression of SOD2, CAT and the mounts of oxidative products. The mitochondrion of GC was damaged seriously. The total numbers decreased and labor interval was prolonged.(3) The pathologic effects were summation by combing repeated superovulation with ozone inhalation.(4) HIF-la proteins staining were seen in the oocyte and granulosa cells of all different developmental stages. The expression of HIF-la increased with the follicle development especially in antral follicle.(5) The expression of HIF-1α,VEGF protein in antral follicle show characteristic increased changes with aging.(6) The expression of HIF-1α,VEGF protein in antral follicle of each treatment group increased compared with control group.(7) Egr-1, Gadd45a proteins were expressed in the oocyte and granulosa cells of all different developmental stages. The expression of Egr-1, Gadd45a increased with the follicle development.Conclusions(1) 10 times repeated superovulation decreased the size of primordial follicle pool with the ovarian reproductive endocrinology functions declining.(2) Ozone inhalation increased oxidative stress in ovary and decreased fertility.(3) Combing repeated superovulation with ozone inhalation established a mouse model to accelerate the progress of ovary aging。(4) HIF-1αaffected the development of follicle by regulated follicle vasculogenesis. (5)The hypoxia status in antral follicle was more and more seirous with aging.(6)Repeated superovulation and oxidative stress increased the expression of HIF-la.(7) The expression of Egr-1, Gadd45a protein especially at the late stage of the follicledevelopment, suggests that the two factors may play important roles in the developmentand atresia of the follicle.