茶多酚对新生大鼠卵巢发育的影响

Effect of Tea Polyphenols on Ovarian Development in Neonatal Rats

目的:探讨茶多酚对新生大鼠卵泡发育和卵母细胞凋亡的影响及相关调控机制。方法:受孕11.5dSD大鼠灌胃茶多酚(100mg/kg,qd)直至分娩,分别用多聚甲醛固定出生后1d、2d、4d、8d龄雌仔鼠卵巢(A组),同时将正常出生后1d的雌幼SD大鼠腹腔注射茶多酚(50mg/kg×1-8d),分别固定出生后2d、4d、8d龄卵巢(B组);所有卵巢经HE染色,观察不同发育阶段的卵泡比例,TUNEL(TdT-mediated dUTP Nick-End Labeling)荧光染色检测卵巢内卵母细胞凋亡变化,免疫组化方法观察叉头转录因子(FOXO3a)、促凋亡因子(Bim)和抗凋亡因子(MnSOD2)在卵巢组织中的表达水平,并以母、幼均未处理的正常同龄大鼠卵巢为对照(C组)。结果:在茶多酚干预组(包括A组和B组)卵巢内,1d、2d龄未装配卵泡比例及4d、8d龄原始卵泡比例均高于C组;A组、B组中卵母细胞TUNEL阳性率显著低于C组;FOXO3a、MnSOD2在A组的1d、2d、4d龄卵巢中的表达高于C组,但二组间的Bim表达水平相一致。结论:茶多酚能延缓新生大鼠卵母细胞巢破裂,抑制原始卵泡的发育启动,减少卵泡的消耗,可能有益于延长卵巢的生殖寿命;茶多酚可能通过上调FOXO3a的活性从而抑制原始卵泡的发育启动,同时通过激活其下游靶分子MnSOD2抑制卵母细胞的凋亡,促进卵母细胞的存活。

Objective： To explore the effect and mechanism of tea polyphenols on ovarian follicle development in neonatal rats. Methods： Pregnant rats were treated with tea polyphenols （100 mg/kg, qd ） by intragastric administration from 11.5 d after the detection of vaginal plug till delivery and neonatal rat ovaries were collected on d 1, 2, 4 and 8 （group A）. Nornal female neonatal rats were also treated with tea polyphenols （50 mg/kg×1-8 d, group B） by intraperitoneal injection from d 1 to d 8 after birth and ovaries were collected on d 2, 4 and 8. Another normal female neonatal rats were not treated as the control （group C）. H.E. staining was performed to investigate the follicle assembly and development. The terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling （TUNEL） was used to detect oocyte apoptosis. The immunohistochemical staining were performed to detect protein expressions of the forkhead transcriptive factor FOXO3a, pro-apoptotic factor Bim and anti-apoptotic factor MnSOD2. Results： The percentage ofunassembled follicles in 1 d-and, 2 d-old rat ovaries and the percentage of primordial follicles in 4 d-and 8 d-old rat ovaries of grouop A and B were higher than those in groupC. The ratio of TUNEL-positive oocytes was decreased in grouop A and B compared with that of group C. The percentage of FOXO3a-and MnSOD2-positive oocytes in group A was higher than that in group C. But the percentage of Bim positive oocytes in two groups was similar. Conclusion： Tea polyphenols may postpone oocytes nest breakdown, inhibit the transition of primordial to developing follicles, and decrease follicle loss in neonatal rats. Tea polyphenols may inhibit the transition of primordial to developing follicles and decrease follicle loss through up-regulation of the expression of FOXO3a and MnSOD2 in oocytes. These results suggest that tea may benefit to prolong the reproductive life of ovary.