营养性肥胖对青春期雄性大鼠睾丸生精细胞凋亡的影响

Diet-induced obesity increases the apoptosis of testicular spermatogenic cells in pubertal male rats

目的:探讨营养性肥胖对青春期雄性大鼠睾丸生精细胞凋亡的影响。方法:健康雄性W istar大鼠40只,随机分为两组,每组20只,对照组给予普通饲料喂养,高脂组用高脂、高热量饲料喂养建立营养性肥胖大鼠模型,10周末处死大鼠摘取睾丸。全自动生化分析仪(ACA)检测外周血总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C);光镜观察睾丸组织病理学改变;TUNEL检测睾丸组织凋亡细胞;免疫组化法检测Bc l-2和Bax蛋白的分布和表达;RT-PCR法检测睾丸组织Bc l-2 mRNA和Bax mRNA的表达。结果:高脂组TC、TG、HDL-C和LDL-C(5.17±0.17、1.18±0.09、1.76±0.11、5.08±0.18)较对照组(1.38±0.12、0.39±0.05、0.97±0.07、0.75±0.06)显著升高(P<0.05);高脂组生精细胞凋亡指数(37.17±2.74)较对照组(5.16±0.81)显著升高(P<0.01),凋亡细胞以精原细胞和精母细胞为主;高脂组Bax蛋白和Bax mRNA(153.26±8.74、1.08±0.12)表达较对照组(101.81±6.14、0.37±0.04)明显升高(P<0.01);高脂组Bc l-2蛋白和Bc l-2 mRNA(139.26±7.21、0.46±0.05)表达较对照组(159.37±8.96、1.05±0.11)明显降低(P<0.01)。结论:营养性肥胖诱导大鼠睾丸生精细胞凋亡增多,其机制可能与Bc l-2表达降低和Bax表达升高相关。

Objective： To investigate the effect of diet-induced obesity on the apoptosis of testicular spermatogenic cells in pubertal male rats. Methods ： Forty healthy male rats were equally and randomly divided into a control and a high-fat group, the former fed on normal diet, while the latter high-fat and high-calorie diet. The testes of the rats were harvested at the end of 10 weeks for detec- tion of total cholesterol （TC）, triglyceride （TG）, high-density lipoprotein cholesterol （HDL-C） and low-density lipoprotein cholesterol （LDL-C） in the peripheral blood with the automatic biochemical analyzer. Pathological changes of the testis were observed under the light microscope, the apoptosis of the testicular cells detected by TUNEL, the expressions of Bcl-2 and Bax proteins determined by immunohistochemistry, and those of Bcl-2 mRNA and Bax mRNA measured by RT-PCR. Results ： The levels of TC, TG, LDL-C and HDL-C were significantly higher in the high-fat group （5.17±0.17, 1.18±0.09, 1.76 ±0.11 and 5.08 ±0.18） than in the control （ 1.38 ±0. 12, 0.39 ± 0.05, 0.97 ± 0.07 and 0.75 ± 0.06） （ P 〈 0.05 ）, so was the apoptotic index of spermatogenic cells （ 37.17 ± 2.74 versus 5.16 ±0.81, P 〈 0. 01 ）, and the apoptotic spermatogenic ceils were mainly spermatogonia and spermatocytes. The expressions of Bax protein and Bax mRNA were markedly higher in the high-fat group （ 153.26 ± 8.74 and 1.08 ± 0.12 ） than in the control （101.81 ± 6.14 and 0.37 ± 0.04） （P 〈 0.01 ）, while those of Bel-2 protein and Bcl-2 mRNA remarkably lower in the former （139.26 ±7.21 and 0.46 ±0.05） than in the latter （159.37 ±8.96 and 1.05±0.11） （P〈0.01）. Conclusion： Diet-induced obesity can increase the apoptosis of spermatogenic cells in the rat testis, which may be associated with the reduced expression of Bcl-2 and elevated expression of Bax.