营养性肥胖大鼠循环瘦素水平和性发育相关指标的变化

目的　观察营养性肥胖大鼠血清中瘦素 (leptin)、雌二醇 (E2 )水平和卵巢发育情况。方法　 2 8天雌性SD大鼠 ,按体重排序 ,选取 6 1～ 10 0百分位点大鼠建立营养性肥胖动物模型 ,4 1～ 6 0百分位点为对照组 ,观察其不同发育时期血清中Leptin和E2水平的变化、卵巢的发育情况及下丘脑促性腺激素释放激素(GnRH)的表达。结果　 15周实验结束时 ,肥胖组大鼠体重较正常对照组超重 2 1 4 % ;实验 6周时改喂普通饲料减肥后 ,体重逐渐接近对照组 ;血中E2水平随鼠龄增加而增加 ,且同期肥胖组雌激素水平高于对照组(尚无统计学意义 ) ;肥胖组大鼠血清中leptin水平明显高于对照组和普食减肥组 (P =0 0 0 0 ) ,并与体重和E2有很好的正相关 (r分别为 0 95 8和 0 896 ,P值分别为 0 0 10和 0 0 39)。肥胖组大鼠较对照组和普食组有更多的成熟卵泡和黄体形成 ,但成熟卵泡的形态明显劣于对照组和普食组。肥胖组下丘脑GnRH表达高于对照组和普食减肥组。结论　雌性肥胖大鼠性发育有提前倾向 ;leptin对肥胖和雌性肥胖大鼠性成熟的提前可能有重要相关作用 ,支持leptin通过促进GnRH分泌而促使其性发育提前的假说

Changes of the circulating leptin levels and sexual development associated index in dietetic obese rats

Objective To observe the serum levels of leptin and estradiol, ovary development. Methods Dietetic obese model were established in female SD rats. Three groups were used: control group, obesity group (fat-enriched diet) and reducing group (fat-enriched diet for 6 weeks, then replaced by a normal diet), and were sacrificed at 0,3,6,9,12 and 15 weeks after the start of the experiment. We measured the serum levels of leptin and estradiol (E2) and observed ovary development by microscope. Results Mean body weight of obese rats was over 21.4% than that of normal rats in the end of experiment. The serum E2 levels increased with age and they were higher in obese group than that in control group at same time point (but P>0.05). The serum leptin levels in obese group were obviously higher than that in control and reducing group(P=0.000), and they showed a positive correlation with body weight and serum E2 levels(r=0.958 and 0.896,P=0.010 and 0.039). There were more mature ovarian follicle and luteum in obese group, but development of them were bad than that of control and reducing group groups. Conclusion There were a tendency of ahead sexual maturation in female obese rats. Leptin probably play an important role in obesity and sexual maturation. This support that Leptin causes a female-specific facilitatory effect on GnRH pulse amplitude.