Objectives: To observe the effects of electroacupuncture (EA) on the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/cAMP response element binding protein (CREB) signaling pathway-related proteins and hippocampal neuron apoptosis in diabetic cognitive impairment (DCI) rats, and to explore the mechanisms of EA in treating DCI.
Methods: Adult male SD rats were randomly divided into normal, model, and EA groups, with 12 rats in each group. The animal model of DCI was replicated using a high-fat, high-sugar diet combined with low-dose streptozotocin. The EA group received EA stimulation at "Yishu" (EX-B6), "Zusanli" (ST36), "Baihui" (GV20), and "Dazhui" (GV14). Blood glucose contents of the rats in each group were measured. The Morris water maze test was used to assess the learning and memory abilities of rats. Transmission electron microscopy was used to observe the ultrastructure of hippocampal CA1 neurons. Nissl staining was used to observe the pathological changes in hippocampal CA1 neurons. TUNEL staining was used to detect the apoptosis in hippocampal CA1 neurons. Western blot was used to detect the protein expression levels of p-PI3K/PI3K and p-Akt/Akt, as well as CREB, p-CREB, cysteine aspartate pro-tease (Caspase)-3, B-cell lymphoma-2 (Bcl-2), and Bcl-2 related X protein (Bax) in the hippocampal tissue of rats.
Results: Compared with the normal group, the rats' random blood glucose contents were significantly increased (P<0.01), the escape latency prolonged (P<0.01), and the original platform crossing counts reduced (P<0.01) in the model group. Significant damage to hippocampal CA1 neurons, a significantly increased neuronal apoptosis index (P<0.01), decreased ratio of p-PI3K/PI3K and p-Akt/Akt and expression of CREB, p-CREB and Bcl-2 proteins, increased expression of Caspase-3 and Bax proteins (P<0.01) were observed in the hippocampal tissue of rats in the model group. Compared with the model group, the rats in the EA group showed decreased random blood glucose content (P<0.01), shortened escape latency (P<0.01), increased original platform crossing counts (P<0.01), improved quantity and pathological morphology and ultrastructure of hippocampal CA1 neurons, reduced neuronal apoptosis index (P<0.01), increased ratio of p-PI3K/PI3K and p-Akt/Akt, and expression of CREB, p-CREB and Bcl-2 proteins (P<0.05, P<0.01) in the hippocampal tissue, and decreased expression of Caspase-3 and Bax proteins (P<0.01).
Conclusions: EA can improve the learning and memory abilities of rats with DCI, and the mechanism may be related to the regulation of the expression of PI3K/Akt/CREB signaling pathway-related proteins, which attenuates the neuronal apoptosis in the hippocampus of rats, and improves the neural function.
目的: 观察电针对糖尿病认知功能障碍（DCI）大鼠海马组织中磷脂酰肌醇-3-激酶（PI3K）/蛋白激酶B（Akt）/ cAMP 反应元件结合蛋白（CREB）信号通路相关蛋白及海马神经元凋亡的影响，探讨电针治疗DCI的部分机制。方法: SD大鼠随机分为正常组、模型组、电针组，每组12只。使用高脂高糖饮食联合小剂量链脲佐菌素复制DCI模型。电针组电针“胰俞”“足三里”“百会”“大椎”，20 min/次，1次/d，每周休息1 d，共治疗4周。检测各组大鼠随机血糖；Morris水迷宫实验评估大鼠学习记忆能力；透射电镜观察大鼠海马CA1区神经元超微结构；尼氏染色法观察大鼠海马CA1区神经元病理形态的改变；TUNEL染色法检测大鼠海马CA1区神经元凋亡情况；Western blot法检测大鼠海马组织中磷酸化（p）-PI3K/PI3K、p-Akt/Akt、CREB、p-CREB、半胱天冬氨酸蛋白酶（Caspase）-3、B细胞淋巴瘤2（Bcl-2）及Bcl-2相关X蛋白（Bax）蛋白表达水平。结果: 与正常组大鼠比较，模型组大鼠随机血糖升高（P<0.01），逃避潜伏期延长（P<0.01），穿越原平台次数减少（P<0.01），海马CA1区神经元损伤明显，神经元细胞凋亡指数显著升高（P<0.01），海马组织中p-PI3K/PI3K、p-Akt/Akt比值，CREB、p-CREB、Bcl-2蛋白表达量降低（P<0.01），Caspase-3、Bax蛋白表达量升高（P<0.01）。与模型组比较，电针组大鼠随机血糖降低（P<0.01），逃避潜伏期缩短（P<0.01），穿越原平台次数增多（P<0.01），海马CA1区神经元的数量、病理形态和超微结构均有所改善，海马神经元细胞凋亡指数降低（P<0.01），海马组织中p-PI3K/PI3K、p-Akt/Akt比值，CREB、p-CREB、Bcl-2蛋白表达量升高（P<0.05，P<0.01），Caspase-3、Bax蛋白表达量降低（P<0.01）。结论: 电针可以改善DCI大鼠学习记忆能力，其机制可能与调控PI3K/Akt/CREB信号通路相关蛋白表达，减轻大鼠海马神经元细胞凋亡，从而改善神经功能有关。.
Keywords: Apoptosis; Diabetic cognitive impairment; Electroacupuncture; PI3K/Akt/CREB signaling pathway.