内质网应激分子在糖尿病大鼠坐骨神经损伤中的变化

Change of endoplasmic reticulum stress-related molecules in the course of sciatic nerve injury of diabetic rats

目的 观察内质网应激（ERS）相关分子在糖尿病大鼠坐骨神经中的变化,探讨ERS在糖尿病周围神经病变中的作用.方法 采用高脂喂养联合腹腔注射链脲佐菌素复制糖尿病大鼠模型.实验按体质量层次随机分为正常对照组及糖尿病组,各组分别在糖尿病造模成功后第4周、8周、12周取材.应用透射电镜观察坐骨神经形态,葡萄糖调节蛋白78（GRP78）、C/EBP同源蛋白 （CHOP）、半胱氨酸蛋白水解酶（Caspase-12）等表达采用qRT-PCR及Western blot方法检测.结果 随着病程进展,糖尿病组大鼠坐骨神经逐渐出现轴索变性等病理改变.糖尿病组大鼠坐骨神经GRP78 mRNA在造模成功后4周以后明显高于正常对照组,其蛋白表达水平在8周及12周明显高于正常对照组（P ＜0.05或P＜0.01）;CHOP mRNA及蛋白表达在造模成功后8周及12周明显高于正常对照组（P＜0.05）;Caspase-12 mRNA及蛋白表达在造模成功后8周及12周明显高于正常对照组（P ＜0.05或P＜0.01）.结论 糖尿病病变过程中ERS相关分子GRP78及CHOP、Caspase-12等参与了坐骨神经损伤.

Objective To investigate the dynamic changes of endoplasmic reticulum stress-related molecules including glucose regulated protein （GRP78）, C/EBP homologous protein （CHOP）, and caspase-12 in sciatic nerve of diabetic rats and explore its mechanisms.Methods Rats were randomly divided into normal control group （NC） and diabetes mellitus group （DM） that were induced by intraperitoneal injection of Streptozocin after 4 weeks of high-fat chow feeding.Sciatic nerves were isolated for three times at 4 weeks, 8 weeks and 12 weeks after induction of diabetes.The expressions of GRP78, CHOP,and caspase-12 were detected with quantitative real-time polymerase chain reaction （qRT-PCR） and Western blot analyses.The morphology of sciatic nerve was investigated with electron microscope.Results With the extension of the course, demyelinating and axonal injury appeared in sciatic nerve of diabetic rats.The expressions of GRP78 mRNA and protein in DM group were significantly higher than NC group at 4 weeks and 8 weeks after induction of diabetes（P 〈0.05, P 〈0.01）.The expressions of CHOP mRNA and protein in DM group were significantly higher than NC group at 8 weeks and 12 weeks after induction of diabetes （P 〈 0.05）.The expressions of caspase-12 mRNA and protein in DM group were significantly higher than NC group at 8 weeks after induction of diabetes（P 〈 0.05, P 〈 0.01）.Conclusions Endoplasmic reticulum stress-related molecules （GRP78, CHOP, and caspase-12） contributed to the peripheral nerve injury of diabetic rats, and displayed dynamic changes.