【摘要】 研究发现二氢杨梅素(Dihydromyricetin,DHM)对中枢神经系统损伤有明显的改善作用。因此,本实验拟观察DHM是否可改善T2DM大鼠认知功能障碍,及其机制是否通过抑制JNK信号从而下调ERS实现。本文采用4w高糖高脂饮食联合STZ一次性腹腔注射的方法构建T2DM模型。接着进行以下检测:尾静脉采血测定空腹血糖,水迷宫(Morris watermaze,MWM)和Y迷宫检测大鼠认知功能,随后断颈处死大鼠,取海马进行苏木精-伊红(Hematoxylin-eosin, HE)染色,观察海马神经细胞损伤情况、WB检测海马组织凋亡蛋白Bax和抗凋亡蛋白Bcl-2的表达水平、Elisa检测海马p-tau,Aβ表达水平。随后分别用或不用DHM处理(250 mg/kg/d,灌胃)12周后,进行上述相关指标的检测,观察DHM对大鼠认知功能、海马损伤的影响。各组剩余大鼠进行侧脑室置管给药(TUDCA,衣霉素,SP600125,茴香霉素)后,在进行上述相关指标的检测的基础上使用WB检测海马组织JNK、p-JNK以及内质网特异性蛋白Bip、p PERK的表达水平。结果发现:高糖高脂饮食4周联合低剂量STZ一次性腹腔注射SD大鼠成功复制T2DM大鼠模型。与Control组相比,T2DM组大鼠出现认知功能障碍,海马神经细胞凋亡、p-tau和Aβ水平增加。DHM能逆转T2DM大鼠上述指标改变,但DHM对Control组大鼠上述指标无显著改变;TUDCA以及SP600125能改善T2DM大鼠认知功能障碍、减少T2DM大鼠海马神经细胞凋亡、p-tau和Aβ蛋白水平。使用ERS激活剂(TUN)以及JNK激活剂(AMY)后SD大鼠的认知功能明显下降,海马神经细胞凋亡、p-tau和Aβ蛋白水平显著增加。综上,我们得出结论:DHM可改善T2DM大鼠认知功能障碍,其机制可能与其抑制JNK缓解ERS,抑制海马神经细胞凋亡、p-tau和Aβ水平有关。更多还原

【Abstract】 Recent studies have demonstrated that dihydromyricetin(DHM) exerts a protective effect against central nervous system injury. Building on these findings, the present study aimed to investigate whether DHM could ameliorate cognitive deficits in a type 2 diabetes mellitus(T2DM) rat model, and to explore whether this effect involved inhibition of the JNK signaling pathway and suppression of endoplasmic reticulum stress(ERS). To establish the T2DM model, Sprague Dawley(SD) rats were fed a high-fat, high-sugar diet in combination with a single intraperitoneal injection of streptozotocin(STZ). Fasting blood glucose levels were measured from tail vein samples, and cognitive performance was evaluated using the Morris water maze(MWM) and Y-maze tests. Following behavioral assessments, the animals were sacrificed by cervical dislocation, and hippocampal tissues were collected for further analysis. Histological examination using hematoxylin-eosin(H&E) staining was performed to assess hippocampal neuronal damage. Western blotting(WB) analysis was employed to quantify the expression of pro-apoptotic protein Bax and anti-apoptotic protein Bcl-2, while ELISA was conducted to measure levels of phosphorylated tau(p-tau) and amyloid-β(Aβ) in the hippocampus. After 12 weeks of oral administration of DHM(250 mg/kg/d), relevant biomarkers were re-evaluated to determine the compound’s impact on cognitive function and hippocampal integrity. Additionally, rats from each group received intracerebroventricular injections of various pharmacological agents, namely, TUDCA(an ERS inhibitor), STZ, SP600125(a JNK inhibitor), and anisomycin(AMY, a JNK activator). WB analysis was further conducted to assess the expression of JNK, phosphorylated JNK(p-JNK), and ERS-associated proteins Bip and p-PERK in hippocampal tissue. The results confirmed that combining a high-fat, high-sugar diet with low-dose STZ injection for 4 weeks effectively established a T2DM model. Compared with the control group, T2DM rats exhibited significant cognitive deficits, increased neuronal apoptosis in the hippocampus, and elevated hippocampal levels of p-tau and Aβ. Notably, DHM treatment markedly reversed these pathological changes in T2DM rats, whereas it had no significant effects on control animals. Moreover, administration of TUDCA and SP600125 similarly mitigated cognitive impairment, neuronal apoptosis, and the accumulation of p-tau and Aβ in diabetic rats. Conversely, activation of ERS and JNK signaling using tunicamycin(TUN) and AMY, respectively, resulted in exacerbated cognitive decline, increased neuronal apoptosis, and higher levels of p-tau and Aβ. In conclusion, these findings suggested that DHM effectively alleviated cognitive dysfunction in T2DM rats, potentially through the inhibition of JNK signaling and subsequent attenuation of ERS, thereby reducing neuronal apoptosis and the pathological accumulation of p-tau and Aβ in the hippocampus.更多还原