[Effects of repeated immobilization stress on hypothalamic-pituitary- ovarian axis in female rats]

Objective: To explore the effects of repeated immobilization stress on hypothalamic-pituitary-ovarian axis in female rats. Methods: Forty female SD rats were randomly divided into two groups: control group (n=20) and experimental group (n=20). One group was fed normally, the other group was subjected to incremental load restraint stress. Brake stress once a day in the retainer (starting at 9: 00 a.m.), braking for 2 hours on the first day, increasing load by 0.5 hours a day for two weeks. Body weight, estrous cycle, sex hormone, organ coefficient, pathology and expression of related genes were detected to explore the harm of hypothalamic-pituitary-ovarian axis. Results: Repeated immobilization stress caused weight loss, prolonged estrous cycle, and changed the organ coefficient and morphology of ovaries and uterus. QPCR technique was used to detect the related genes. It was found that the expressions of gonadotropin releasing hormone, pituitary gonadotropin releasing hormone receptor, follicle stimulating hormone and luteinizing hormone mRNA were decreased significantly, while the expressions of ovarian follicle stimulating hormone and luteinizing hormone receptor mRNA were increased significantly. The expression of estrogen receptor mRNA in ovary and uterus was decreased significantly. Conclusion: Repeated immobilization stress may disrupt the estrous cycle by interfering with the endocrine regulation of the hypothalamic-pituitary-ovarian axis, thus damaging the gonadal and reproductive endocrine function of female animals.