Abstract: In order to explore the protective effect of different doses of Gynostemmapentaphyllum polysaccharides （GPP） on oxidative damage of ovary in mice caused by heat stress, enzyme-linked immunosorbent assay （ELISA）, immunohistochemical techniques and other research methods were used to observe and analyze the body weight and ovarian index, the number of follicles at all levels, the maximum diameter and the thickness of ovarian cortex, various reproductive hormones in ovary, the level of estrogen receptor β expression, antioxidant capacity in blood serum and the apoptosis rate of ovarian granulosa cells. The results showed that compared with group HS, the weight of mice in different doses of GPP was significantly higher （P<0.05）;the number of primordial follicles in group GPP-H was significantly higher （P<0.05）; the number of atretic follicles in groups GPP-L and GPP-H was significantly lower （P<0.05）;the thickness of ovarian cortex, the maximum diameters of primordial follicle, primary follicle and corpus luteum in different doses of GPP were significantly larger （P<0.05）; the secretion of GnRH, E₂ and P₄ in different doses of GPP was significantly higher, the secretion of FSH in group GPP-H was significantly higher （P<0.05）; GSH-Px activity indifferent doses of GPP was significantly higher （P<0.05）, T-SOD activity in group GPP-M was significantly higher （P<0.05）, the content of MDA in different doses of GPP was significantly lower （P<0.05）. In conclusion, GPP could improve the endocrine function of pituitary and ovary, restore and protect the ovarian reserve capacity, enhance the activity of enzyme antioxidant system, and alleviate the oxidative damage of ovary caused by heat stress by exerting the steroid-like effect of ER agonist, in which GPP-H worked most efficiently.

Key words: ovary, oxidative damage, heat stress, Gynostemma pentaphyllum polysaccharides, mice