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中老龄雄性大鼠雄激素减低与代谢关系及发病机制的研究
Elationship between Metabolism and Decreasing Serum Testosterone Levels in Aging Male Rats
【作者】 关迪；
【导师】 谷翊群；
【作者基本信息】 北京协和医学院 ， 外科学， 2011， 硕士
【摘要】 目的：研究中老龄雄性大鼠雄激素减低与代谢的关系,雄激素减低发生的机制,尤其是睾丸间质细胞数量、形态及分泌功能的变化。方法：分别取9月龄(青年)和12、15、18、21月龄(中老年)雄性SD大鼠每月龄组6只,静脉血检测大鼠代谢指标的变化,包括高密度脂蛋白(high density lipoprotein, HDL)、低密度脂蛋白(low density lipoprotein, LDL)、甘油三酯(triglyceride, TG)、总胆固醇(total cholesterol, TC)、血糖(glucose, Glu)、胰岛素(insulin, INS)、胰高血糖素(immunoreactive glucagon, IRG)、瘦素(Leptin,LP)含量；检测大鼠血清激素的改变,包括总睾酮(total Testosterone, tT)、黄体生成素(luteinizing hormone, LH)、卵泡刺激素(follicle-stimulating hormone,FSH)；通过组织切片观察大鼠睾丸间质细胞形态学变化；使用人绒毛膜促性腺激素(human chorionic gonadotrophin, hCG)、毛喉素(Forskolin)刺激体外培养的大鼠睾丸间质细胞,比较培养基中睾酮浓度；采用脱氧核苷酸转移酶介导的dUTP缺口末端标记(deoxynucleotidyl transferase mediated dUTP nick end labeling assay, TUNEL)检测方法检测大鼠睾丸间质细胞凋亡率；分离称重内脏脂肪,计算内脏脂肪/体重比及Lee’s指数。结果：中老龄大鼠的血清tT[(1.26±0.65)ng/ml]比青年大鼠[(3.24±0.38) ng/ml]显著降低(P<0.01)；中老龄大鼠睾酮分泌指数(testosterone secretion index, TSI) [(0.07±0.05) ng/mIU]比青年大鼠[(0.21±0.01)ng/mIU]显著降低(P<0.01)；不同年龄大鼠睾丸间质细胞形态有较显著差异；体外培养的中老龄大鼠睾丸间质细胞分泌量显著降低(P<0.05)；中老龄大鼠睾丸间质细胞TUNEL阳性率(17.36%±1.31%)比青年大鼠(7.02%±1.05%)显著升高(P<0.01)；中老龄组和青年组大鼠IRG、HDL、LDL、TG、TC及内脏脂肪含量有显著性差异(P<0.05)。结论：中老龄大鼠血清tT浓度显著低于青年大鼠,代谢指标随血清tT降低发生规律改变；中老龄大鼠雄激素减低可能与睾丸间质细胞分泌功能衰退、间质细胞数量减少及垂体功能衰退有关。
【Abstract】 Objective:To investigate the mechanism and relationship between metabolism and decreasing serum testosterone levels in aging male rats, especially the changes of Leydig cells in morphology, quantity and capacity of secreting testosterone.Methods:The levels of serum total testosterone (tT) LH, FSH, HDL, LDL, TG, TC, Glu, INS, IRG, LP of both young (9 m) and aging rats (12 m,15 m,18 m and 21m) were examined. The morphological changes of Leydig cells in microscopic characteristics between young and aging rats were observed under microscope. The testosterone levels secreted by cultured Leydig cells stimulated by hCG and Forskolin for both groups were detected. Leydig cells DNA fragmentation of both groups were measured with TUNEL, Separated visceral fat was weighted and Lee’s index was calculated.Results:With the increase of age in rats, the levels of serum LH, FSH did not change significantly (P> 0.05), while the levels of serum tT and TSI of aging rat group decreased significantly (P< 0.01) compared with young rat group. Leydig cells of aging rats were found to be smaller in volume and more marked staining than young ones. The secretion capacity of Leydig cells in aging rats was found to be lower than that of young rat with or without hCG and Forskolin stimulation (P< 0.05). Positive rate of TUNEL in the aging rat group was significantly higher than that in the young rat group (P< 0.01). Statistically significant differences were found between the two different age groups in all the biochemical parameters including IRG, HDL, LDL, TG, TC and visceral fat content (P< 0.05), except for the levels of serum Glu, INS, LP (P> 0.05).Conclusion:The serum T levels and secreting capacity of Leydig cells in vitro in aging rats are lower than that of young rats. The metabolic parameters changed with aging rats in a gradient manner. The mechanism of testosterone decreasing in aging rats are mainly caused by dysfunction of Leydig cells, increasing positive rate of TUNEL, and decline of pituitary function.