内质网应激在糖尿病大鼠海马神经元凋亡中的作用及机制

The effect and mechanism of endoplasmic reticulum stress on hippocampal neuron apoptosis of diabetic rats

目的观察内质网应激在1型糖尿病大鼠海马神经元凋亡及认知功能障碍中的作用并探讨其作用机制。方法 30只Wistar大鼠随机抽取10只为正常对照组(Con组),余20只一次性腹腔注射链脲佐菌素制备1型糖尿病模型,将造模成功大鼠随机均分为糖尿病组(DM组)和糖尿病+Salubrinal组(DM+Sal组)。DM+Sal组大鼠侧脑室注射Salubrinal(75μmol/L,1μL),Con组和DM组给予等量生理盐水。采用Morris水迷宫实验检测大鼠认知功能,TUNEL、流式细胞术检测海马神经元凋亡情况,Western blot及Real-time PCR技术检测内质网应激标志分子GRP78、CHOP、Caspase12蛋白及GRP78、CHOP mRNA表达。结果与Con组比较,DM组大鼠认知功能明显降低,海马神经元凋亡率增加,内质网应激标志分子GRP78、CHOP、Caspase12蛋白表达明显增加(P<0.05),GRP78和CHOP mRNA表达增加(P<0.05);加入Salubrinal后,与DM组比较,DM+Sal组大鼠认知功能有所改善,海马神经元凋亡率降低,同时,GRP78、CHOP、Caspase12蛋白表达降低(P<0.05),GRP78和CHOP mRNA表达也降低(P<0.05)。结论糖尿病大鼠认知功能障碍,海马神经元凋亡率增加,内质网应激可能在其中发挥了重要作用。

Objective To study the effect and mechanism of endoplasmic reticulum stress on hippocampal neuronapoptosis and cognitive impairment in type1diabetic rats.Methods Ten rats were randomly selected as normal controlgroup(Con group)from thirty Wistar rats,and the remaining twenty rats were intraperitoneally injected with streptozotocin toprepared for type1diabetic rat model.The successful model rats were randomly divided into diabetic group(DM group)anddiabetic+Salubrinal group(DM+Sal group).Rats of DM+Sal group were injected by lateral ventricle with Salubrinal(75μmol/L,1μL).Rats of Con group and DM group were given the equal volume of normal saline.The rat cognitive functionwas assayed by Morris water maze test.The hippocampal neuron apoptosis was detected by TUNEL and flow cytometrymethods.The protein levels of endoplasmic reticulum stress markers,GRP78,CHOP and Caspase12,and the mRNA levelsof GRP78and CHOP,were examined by Western blot assay and Real-time PCR,respectively.Results Compared with theCon group,the cognitive function was significantly decreased in DM group,and the apoptotic rate of hippocampal neuronswas increased.The protein levels of endoplasmic reticulum stress markers GRP78,CHOP and Caspase12were significantlyincreased(P<0.05),and the mRNA levels of GRP78and CHOP were also higher in DM group(P<0.05).After the injectionwith Salubrinal,the cognitive function was improved and hippocampal neuron apoptotic rate was decreased in DM+Sal groupcompared with those of DM group.Moreover,the protein levels of GRP78,CHOP and Caspase12were significantlydecreased(P<0.05)and the mRNA levels of GRP78and CHOP were also lowered in DM+Sal group(P<0.05).Conclusion The cognitive impairment and the higher apoptotic rate appear in the diabetic rats,and endoplasmic reticulumstress may play an important role in it.