内质网应激在高脂血症大鼠睾丸生殖细胞凋亡中的作用

Endoplasmic reticulum stress promotes the apoptosis of testicular germ cells in hyperlipidemic rats

目的:探讨内质网应激途径在高脂血症大鼠睾丸生殖细胞损伤中的作用。方法:42只雄性Wistar大鼠于鼠龄4周末随机化分为两组:对照组(12只)和高脂组(30只),分别给予普通饲料和高脂高热量饲料喂养建立高脂血症大鼠模型。第10周末(即鼠龄14周)全自动生化分析仪检测外周血甘油三酯(TG)和总胆固醇(TC)含量,TUNEL法检测睾丸组织中凋亡生殖细胞,免疫组化法检测睾丸组织中葡萄糖调节蛋白78(GRP78)及caspase-12蛋白表达,RT-PCR法检测睾丸组织GRP78及caspase-12 mRNA的表达。结果:高脂组大鼠血清TG、TC[(3.00±0.92)mmol/L、(3.04±0.39)mmol/L]较对照组[(1.43±0.41)mmol/L、(1.55±0.23)mmol/L]显著升高(P<0.01),睾丸生殖细胞凋亡指数[(37.17±2.74)%]较对照组[(5.16±0.81)%]显著升高(P<0.01);以精原细胞和精母细胞凋亡为主。高脂组睾丸组织中GRP78蛋白(0.32±0.03)及caspase-12蛋白(0.34±0.02)表达较对照组(0.19±0.01、0.12±0.01)明显升高(P<0.01),GRP78 mRNA及caspase-12 mRNA(0.86±0.05、0.87±0.01)较对照组(0.37±0.03、0.34±0.03)明显增加(P<0.01)。结论:高脂血症大鼠睾丸生殖细胞凋亡增多;内质网应激可能是高脂血症大鼠睾丸生殖细胞凋亡的主要途径之一。

Objective：To investigate the role of endoplasmic reticulum stress in the apoptosis of testicular germ cells in hyperlipidemic rats.Methods：We randomly assigned 42 four-week-old male Wistar rats into a normal control group（ n = 12） and a highfat group（ n = 30） to be fed on a normal diet and a high-fat diet,respectively,for 10 weeks.Then we measured the concentrations of triglyceride（ TG） and total cholesterol（ TC） in the serum using an automatic biochemistry analyzer,detected the apoptosis of testicular germ cells by TUNEL staining,and determined the protein and mRNA expressions of GRP78 and caspase-12 in the testis tissue by immunohistochemistry and RT-PCR,respectively.Results：The concentrations of TG and TC were significantly increased in the animals of the high-fat group（ [3.00 ± 0.92] and [3.04 ± 0.39] mmol / L） as compared with the control rats（[1.43 ± 0.41] and [1.55 ±0.23] mmol / L）（ P 〈0.01）,and so was the apoptosis index of the testicular germ cells（[37.17 ± 2.74]% vs [5.16 ± 0.81]%,P 〈0.01）.The high-fat group,in comparison with the control,also showed remarkably upregulated protein and mRNA expressions of GRP78（0.32 ± 0.03 and 0.86 ± 0.05 vs 0.19 ± 0.01 and 0.37 ± 0.03,P 〈0.01） and caspase-12（0.34 ± 0.02 and 0.87 ± 0.01 vs0.12 ± 0.01 and 0.34 ± 0.03,P 〈0.01） in the testis tissue.Conclusion：The apoptosis of testicular germ cells is increased in hyperlipidemic rats,which may be attributed to endoplasmic reticulum stress.