次黄苷对大鼠糖尿病认知障碍的治疗作用及其机制

Therapeutic effect of inosine on diabetic cognitive impairment in rats and its mechanism

目的 观察次黄苷对大鼠糖尿病认知障碍(DCI)的治疗作用,并探讨其机制。方法 将SD雄性大鼠随机分为对照组、模型组、实验组,模型组和实验组采用高脂饲料联合腹腔注射链脲佐菌素构建并经Morris水迷宫实验筛选得到DCI模型,对照组不制作模型;实验组造模成功后给予100 mg/kg次黄苷腹腔注射,对照组和模型组给予等量生理盐水腹腔注射,每天1次,连续4周。采用Morris水迷宫实验检测大鼠认知能力;HE染色观察海马神经元细胞形态;ELISA法检测海马组织中的肿瘤坏死因子(TNF)-α、白细胞介素(IL)-1β、IL-6、丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px);分别采用RT-PCR法和Western blotting法检测海马组织中的磷酸肌醇-3-激酶(PI3K)/蛋白激酶B(AKT)/哺乳动物雷帕霉素靶蛋白(mTOR)信号通路分子的mRNA和蛋白。结果 与对照组相比,模型组逃避潜伏期增加,穿越平台次数减少(P均<0.05);与模型组相比,实验组逃避潜伏期减少,穿越平台次数增加(P均<0.05)。模型组海马神经细胞排列松散,细胞形态不规则,细胞数量明显减少;实验组海马神经细胞排列相对整齐,形态较规则,细胞数量增加。与对照组相比,模型组海马组织TNF-α、IL-1β、IL-6、MDA水平升高,SOD、GSH-Px水平降低(P均<0.05);与模型组相比,实验组TNF-α、IL-1β、IL-6、MDA水平降低,SOD、GSH-Px水平升高(P均<0.05)。模型组PI3K、AKT、mTOR mRNA及PI3K、p-AKT、p-mTOR蛋白表达低于对照组(P均<0.05);实验组PI3K、AKT、mTOR mRNA及PI3K、p-AKT、p-mTOR蛋白表达高于模型组(P均<0.05)。结论 次黄苷能够改善DCI大鼠的认知和学习记忆能力,减轻认知障碍,其机制可能与激活PI3K/AKT/mTOR信号通路、减轻炎症反应和氧化应激有关。

Objective To observe the therapeutic effect of inosine on diabetic cognitive impairment(DCI)in rats and to explore its mechanism.Methods SD male rats were randomly divided into the control group,model group,and experimental group,respectively.Rats in the model group and experimental group were treated with high-fat diet com-bined with the intraperitoneal injection of streptozotocin and were screened out by Morris water maze experiment to obtain the DCI models,except rats in the control group.After successful modeling,rats in the experimental group were intraperi-toneally injected with 100 mg/kg inosine,and rats in the control group and the model group were intraperitoneally injected with the same volume of normal saline,once a day,for 4 weeks.Morris water maze test was used to detect the cognitive ability of rats.HE staining was used to observe the morphology of hippocampal neurons.ELISA was used to detect the lev-els of tumor necrosis factor-α(TNF-α),interleukin(IL)-1β,IL-6,malondialdehyde(MDA),superoxide dismutase(SOD),and glutathione peroxidase(GSH-Px)in hippocampus.RT-PCR and Western blotting were used to detect the mRNA and protein expression levels of phosphatidylinositol-3-kinase(PI3K)/protein kinaseB(AKT)/mammalian target of rapamycin(mTOR)signaling pathway.Results Compared with the control group,the escape latency increased,and the number of crossing the platform decreased in the model group(both P<0.05).Compared with the model group,the es-cape latency decreased,and the number of crossing the platform increased in the experimental group(both P<0.05).In the model group,the hippocampal neurons were loosely arranged and irregularly shaped,and the number was significantly reduced.The hippocampal neurons of the experimental group were relatively neatly arranged and the morphology was regu-lar,and the number increased.Compared with the control group,the levels of TNF-α,IL-1β,IL-6,and MDA in the hip-pocampus of the model group increased,and the levels of SOD and GSH-Px decreased(all P<0.05).Compared with the model group,the levels of TNF-α,IL-1β,IL-6,and MDA in the hippocampus of the experimental group decreased,and the levels of SOD and GSH-Px increased(all P<0.05).The mRNA expression levels of PI3K,AKT,and mTOR and the protein expression levels of PI3K,p-AKT,and p-mTOR were lower in the model group than in the control group(all P<0.05).The mRNA expression levels of PI3K,AKT,and mTOR and the protein expression levels of PI3K,p-AKT,and p-mTOR in the experimental group were higher than those in the model group(all P<0.05).Conclusions Inosine can im-prove the cognition and learning memory in DCI rats,thus alleviating cognitive impairment.The mechanism may be relat-ed to activating PI3K/AKT/mTOR signaling pathway and reducing inflammatory response and oxidative stress.