Objective: To observe the effect of acupuncture on the protein kinase R-like endoplasmic reticulum kinase (PERK)/eukaryotic translation initiation factor 2α (eIF2α) signaling pathway in the hippocampus of rats with post-traumatic stress disorder (PTSD), so as to explore the underlying mechanism of acupuncture in treating PTSD.
Methods: Twenty-eight SD rats were randomly divided into normal, model, acupuncture and sertraline groups, with 7 rats in each group. The PTSD model was established by single prolonged stress method. The next day after modeling, acupuncture was applied to "Baihui" (GV20) and "Dazhui" (GV14) of rats in the acupuncture group for 10 min, once a day for 7 days. Sertraline (10 mg/kg) was given by gavage to rats of the sertraline group daily for 7 days. The behavioral changes of rats were detected by elevated cross maze experiment and new object recognition experiment. The expression levels of PERK,phosphorylated(p)-PERK, eIF2α, p-eIF2α and activating transcription factor 4 (ATF4) proteins in hippocampus were detected by Western blot. The ultrastructure of hippocampal neurons was observed by transmission electron microscopy.
Results: Compared with the normal group, the percentage of times and retention time of entering the open arm of the elevated cross maze experiment, and new object recognition index were significantly decreased (P<0.01); the expression levels of p-PERK, p-eIF2α and ATF4 proteins in hippocampus were significantly increased (P<0.05) of rats in the model group. Compared with the model group, the percentage of times and retention time of entering the open arm, and new object recognition index were significantly increased (P<0.05，P<0.01), the expression levels of p-PERK, p-eIF2α and ATF4 proteins in hippocampus were significantly decreased (P<0.05, P<0.01) of rats in the acupuncture and sertraline groups; the expression level of eIF2α protein was significantly decreased (P<0.05) in the sertraline group. Hippocampal neurons in the model group were damaged, the rough endoplasmic reticulum showed severe dilation, the mitochondrial cristae showed reduction or mild cavitation; compared with the model group, hippocampal neurons structural damage and the rough endoplasmic reticulum dilation were alleviated， and only some of the mitochondrial cristae decreased in the acupuncture and sertraline groups.
Conclusion: Acupuncture can alleviate the anxiety behavior as well as the recognition and memory ability of PTSD rats, and its mechanism may be related to the inhibition of hippocampus PERK/eIF2α signaling pathway and the reduction of hippocampal neuron damage caused by endoplasmic reticulum stress.
目的：观察针刺对创伤后应激障碍(PTSD)大鼠海马蛋白激酶R样内质网激酶(PERK)/真核细胞起始因子2α(eIF2α)信号通路的影响，探讨针刺治疗PTSD的可能机制。方法：SD大鼠随机分为正常组、模型组、针刺组、舍曲林组，每组7只。采用单次延长应激法制备PTSD大鼠模型。针刺组针刺“百会”“大椎”，每次10 min，每日1次，连续7 d；舍曲林组给予盐酸舍曲林溶液(10 mg/kg)灌胃，连续7 d。采用高架十字迷宫实验、新物体识别实验检测大鼠行为学变化；Western blot法检测大鼠海马PERK、磷酸化(p)-PERK、eIF2α、p-eIF2α、转录激活因子4(ATF4)蛋白表达；透射电镜观察大鼠海马神经元超微结构。结果：与正常组比较，模型组大鼠高架十字迷宫实验开臂次数百分比和开臂时间百分比、新物体识别指数显著降低(P<0.01)；海马p-PERK、p-eIF2α、ATF4蛋白表达显著升高(P<0.05)。与模型组比较，针刺组、舍曲林组大鼠高架十字迷宫实验开臂次数百分比和开臂时间百分比、新物体识别指数显著升高(P<0.05，P<0.01)，海马p-PERK、p-eIF2α、ATF4蛋白表达显著降低(P<0.05，P<0.01)，舍曲林组eIF2α蛋白表达显著降低(P<0.05)。与正常组比较，模型组海马神经元损伤，粗面内质网重度扩张，线粒体多呈嵴减少或少量空泡化；与模型组比较，针刺组、舍曲林组海马神经元结构损伤减轻，粗面内质网未见明显扩张，部分线粒体呈嵴减少。结论：针刺可以缓解PTSD大鼠焦虑行为和提高识别记忆能力，其机制可能与抑制海马PERK/eIF2α信号通路，改善内质网应激造成的海马神经元损伤有关。.
Keywords: Acupuncture; Endoplasmic reticulum stress; Post-traumatic stress disorder; Protein kinase R-like endoplasmic reticulum kinase/eukaryotic translation initiation factor 2α.