Effect Of Plant Polyphenols On Rat Ovary Senescence

Objective: To investigate the effects of curcumin on ovarian follicular development and oocyte apoptosis in neonatal rats.Materials and Methods: 24 Female SD rats were divided into 3 groups: Intragastric administration group (pregnant rats were treated with curcumin (100 mg﹒kg^-1﹒d^-1) from day 11.5 of their pregnancy to delivery, and neonatal rat ovaries from postnatal day 1 (PD 1), PD 2 and 4 rats were collected respectively); Intraperitoneal injection group (normal PD 1 rats were treated with curcumin (100 mg﹒kg^-1﹒d^-1) consecutively for 4 days, and PD 2 and 4 ovaries were collected); Control group (ovaries from normal PD 1, 2 and 4 rats without any treatments were collected). Ovarian tissue sections were prepared and hematoxylin and eosin (HE) staining was performed to examine the ratio of ovarian follicles at different developmental stages and TUNEL staining to analyze the ratio of apoptotic oocytes among groups.Results: In PD 1 ovaries, the ratio of unassembled follicles from intragastric administration group was significantly slower than that of control group. In PD 2 ovaries, intraperitoneal injection group exhibited significantly lower ratio of unassembled follicles but higher ratio of primordial follicles than control group. In PD 4 ovaries, compared with control group, the ratio of primordial follicles from intraperitoneal injection group decreased remarkably while both the ratio of early primary follicles and that of developing follicles increased remarkably. In PD 1 and 2 ovaries, both intragastric administration and intraperitoneal injection group demonstrated significantly less apoptotic oocytes than control group.Conclusion: Curcumin may promote oocyte nest breakdown and speed up primordial follicle development in neonatal rats, as well as inhibit oocyte apoptosis. Objective: To investigate whether the four kinds of plant polyphenols can increase ovarian follicular reserve and prolong reproductive lifespan of rat.Materials and Methods: 54 11-month-old rats were accepted intragastric administration with tea polyphenols (100 mg﹒kg^-1﹒d^-1), quercetin (meletin) (50 mg﹒kg^-1﹒d^-1), genistein (160 mg﹒kg^-1﹒d^-1) and resveratrol (25 mg﹒kg^-1﹒d^-1) respectively once a day for 4 months (from age of 12 to 15 months). Vaginal swears were performed to examine the estrous cycle phase. Rats were weighed once a week to detect the effect of drugs on body weight. At the end of the study, ovaries from each rat were isolated and sectioned for HE staining, and follicular and oocyte survival were assessed by histological morphometry. The total number of follicles of 5 representative ovarian sections and the percentage of follicles at different developmental stages were calculated and presented as the Mean±SEM. Differences between groups were analyzed for statistical significance by using One - Way ANOVA test and Chi - Square test (SPSS 13.0).Result: Tea polyphenol - treated (27.8±3.2) rats had a comparable total number of healthy follicles to those of controls (26.9±3.8), while signigicantly less atretic follicles was observed (43.4±5.9 vs 79.7±7.5) (P < 0.001). Both total number of healthy follicles (36.5±4.1) and of atretic follicles (68.8±6.7) of quercetin-treated rats were comparable to those of controls. Remarkably, both genistein- and resveratrol-treated rats had remarkably more healthy follicles (42.8±3.9, 51.9±6.4) (P < 0.05, P < 0.001) and less atretic follicles (58.4±8.0, 51.0±6.2) (P < 0.05, P < 0.01) than those of controls.Conclusion: Tea polyphenols have no significant effects on promoting follicular survival and on slowing down follicular development, but can protect follicles from atresia. Quercetin have no remarkably positive or negative effects on follicular survival or development at all. However, both genistein and resveratrol can increase ovarian follicular reserve and prolong ovarian lifespan in rats, and their positive effects may be due to not only their intervention in the transition from primordial to primary follicle but also the inhibiting effect on follicular atresia.