营养性肥胖大鼠弓状核促性腺激素释放激素的表达变化以及对精子发生的影响

Expression of GnRH in the hypothalamic arcuate nucleus in rats with diet-induced obesity and its influence on spermatogenesis

目的：探讨营养性肥胖大鼠弓状核神经肽Y（NPY）、瘦素受体（ob-R）及与生殖相关的促性腺激素释放激素（GnRH）表达变化以及对精子发生的影响。方法：免疫组织化学观察NPY、ob-R及GnRH在肥胖模型组下丘脑弓状核的表达情况以及睾丸支持细胞雄激素结合蛋白（ABP）表达变化；流式细胞分析检测睾丸生精细胞周期的改变。并测定血清中瘦素、睾酮、卵泡刺激素（FSH）和黄体生成素（LH）的水平。结果：肥胖大鼠血清中瘦素水平较对照组明显升高，睾酮、FSH、LH水平较对照组明显降低；下丘脑弓状核NPY表达较对照组增强，ob-R及GnRH表达较对照组减弱，ABP表达较对照组减弱；肥胖大鼠S期细胞显著下降，G2／M期细胞的百分数明显增多。结论：营养性肥胖大鼠由于神经内分泌代谢失调而引起GnRH水平降低，导致下丘脑-垂体-睾丸轴功能失调引起睾丸间质细胞及支持细胞功能降低，致使精子发生障碍，可能导致不育。

Objective： To investigate the expressions of neuropeptide Y （NPY）, obesity receptor （ob-R） and gonadotropin-re- leasing hormone （GnRH） in the hypothalamic arcuate nucleus in rats with diet-induced obesity and its influence on spermato- genesis. Methods： Weanling SD male rats were fed with high-energy feed. After 14 weeks, obesity models were selected ac- cording to I.ee＇s Index. The rats in the control group were established by feeding them with normal feed. We observed the ex- pressions of NPY, ob-R and GnRH in the hypothalamic arcuate nucleus and the expression of androgen binding protein （ABP） in the testis and the changes of spermatogenic cells cycle with obesity. We also detected the level of leptin, follicule-stimula- ting hormone （FSH）, luteinizing hormone （LH） in serum and the concentration of testosterone in venous blood of testicle. Results： The level of leptin was higher in the obesity group than in the control group. The levels of testosterone, FSH and LH were lower than that in the control group. The expression of NPY increased, and the expressions of ob-R and GnRH de- creased, as compared with the control group. The expression of ABP in testicles in obesity models was attenuated. The sper- matogenic cells in S phase in obesity model decreased, while the cells in G2/M phase significantly increased. Conclusion： The low level of GnRH induced by neuroendocrine metabolic disorder lead to dysfunction of hypothalamic-pituitary-testicular axis, resulting in impediment of spermatogenesis, which might result in infertility.