雌激素受体GPER通过抑制内质网应激减轻脑缺血再灌注损伤

G protein-coupled estrogen receptor alleviates cerebral ischemia-reperfusion injury through inhibiting endoplasmic reticulum stress

本文旨在研究G蛋白耦联雌激素受体(G protein-coupled estrogen receptor, GPER)是否通过作用于内质网应激(endoplasmic reticulum stress, ERS)减轻脑缺血再灌注损伤(cerebral ischemia-reperfusion injury, CIRI)中的海马神经元损伤。采用大脑中动脉栓塞法(middle cerebral artery occlusion, MCAO)制备CIRI动物模型。选取雌性去卵巢(ovariectomized, OVX) Sprague-Dawley(SD)大鼠,随机分为4组:对照(Control)组、缺血再灌注损伤(MCAO)组、溶媒(MCAO+DMSO)组、GPER特异性激动剂G1(MCAO+G1)组。用Longa评分法对大鼠进行神经行为学评分,用尼氏染色法观察神经元形态学改变,用TTC染色法检测脑梗死情况,用TUNEL染色法检测海马CA1区神经元凋亡情况,用免疫荧光染色技术观察海马CA1区GRP78 (78 kDa glucoseregulatedprotein78)的分布和表达,用Westernblot检测GRP78、Caspase-12、CHOP和Caspase-3蛋白表达水平,用real-time PCR检测GRP78、Caspase-12、CHOPmRNA水平。结果显示,与对照组相比,MCAO组大鼠神经行为学评分、脑梗死体积、细胞凋亡指数、GRP78、Caspase-12和CHOP蛋白和mRNA表达水平均显著升高。而G1可逆转MCAO组大鼠的上述变化。以上结果提示,激活GPER可减少神经元凋亡,减轻大鼠CIRI,其机制可能涉及GPER对ERS的抑制。

The aim of this study was to investigate whether G protein-coupled estrogen receptor(GPER)could alleviate hippocampal neuron injury under cerebral ischemia-reperfusion injury(CIRI)by acting on endoplasmic reticulum stress(ERS).The CIRI animal model was established by middle cerebral artery occlusion(MCAO).Female ovariectomized(OVX)Sprague-Dawley(SD)female rats were randomly divided into 4 groups:control,ischemia-reperfusion injury(MCAO),vehicle(MCAO+DMSO),and GPER-specific agonist G1(MCAO+G1)groups.The neurobehavioral score was assessed by the Longa score method,the morphological changes of the neurons were observed by the Nissl staining,the cerebral infarction was detected by the TTC staining,and the neural apoptosis in the hippocampal CA1 region was detected by TUNEL staining.The distribution and expression of GRP78(78 kDa glucose-regulated protein 78)in the hippocampal CA1 region were observed by immunofluorescent staining.The protein expression levels of GRP78,Caspase-12,CHOP and Caspase-3 were detected by Western blot,and the mRNA expression levels of GRP78,Caspase-12,and CHOP were detected by the real-time PCR.The results showed that the neurobehavioral score,cerebral infarct volume,cellular apoptosis index,as well as GRP78,Caspase-12 and CHOP protein and mRNA expression levels in the MCAO group were significantly higher than those of control group.And G1 reversed the above-mentioned changes in the MCAO+G1 group.These results suggest that the activation of GPER can decrease the apoptosis of hippocampal neurons and relieve CIRI,and its mechanism may involve the inhibition of ERS.