四君子汤对糖尿病引起记忆损伤小鼠的神经保护作用

on diabetes mellitus-associated cognitive impairment in mice

目的 探究四君子汤对1型糖尿病引起认知损伤小鼠的神经保护作用。方法 ICR小鼠腹腔注射STZ,4周后通过Morris水迷宫实验筛选记忆损伤小鼠。记忆损伤小鼠随机分为模型组、雷帕霉素组和四君子汤低、中、高剂量组(1.56、3.12、6.24 g/kg),检测血糖和体质量,给药6周后检测糖耐量,ELISA法检测血清胰岛素水平,Morris水迷宫实验检测学习记忆能力,条件恐惧实验检测恐惧记忆消退能力,HE染色和尼氏染色观察脑组织病理变化,试剂盒检测海马组织SOD活性和MDA水平,Western blot法检测海马组织p-AMPK、p-mTOR、NR^(2)A、NR^(2)B、NR1、Shank 3、PSD 95蛋白表达。结果 腹腔注射STZ能诱导小鼠出现认知功能障碍。与模型组比较,四君子汤能降低糖尿病小鼠血糖,改善认知功能障碍,减轻海马组织神经元细胞损伤,抑制氧化应激反应,上调海马组织中p-AMPK、Shank 3、PSD 95、NR^(2)A、NR^(2)B、NR1蛋白表达,下调p-mTOR蛋白表达。结论 四君子汤能提高糖尿病小鼠胰岛素敏感性,改善糖尿病引起的认知功能障碍,减轻神经元细胞损伤,其机制可能与通过AMPK/mTOR信号通路调控突触蛋白表达、保护海马突触稳态、改善突触功能有关。

AIM To investigate the neuroprotective effects of Sijunzi Decoction on type 1 diabetes mellitus(DM)-associated cognitive impairment in mice.METHODS Four weeks after the intraperitoneal injection of STZ,the ICR mice with memory impairment confirmed by Morris water maze experiment were selected and randomly divided into the model group,the rapamycin group and the low-dose,medium-dose,and high-dose Sijunzi Decoction groups(1.56,3.12,and 6.24 g/kg).The mice had their levels of blood glucose and body mass detected;their glucose tolerance detected followed by 6 weeks corresponding administration,their serum insulin levels detected by ELISA;their learning and memory abilities assessed by Morris water maze experiment;their extinction of fear memory assessed by conditioned fear experiment;their histopathological changes in brain observed by HE staining and Nissl staining;their hippocampal SOD activity and MDA level detected by kits;and their hippocampal protein expressions of p-AMPK,p-mTOR,NR^(2)A,NR^(2)B,NR1,Shank 3 and PSD 95 detected by Western blot.RESULTS Intraperitoneal injection of STZ induced cognitive dysfunction in mice.Compared with the model group,the Sijunzi Decoction groups displayed reduced blood glucose,ameliorated cognitive dysfunction,attenuated hippocampal neuronal cell damage,inhibited hippocampal oxidative stress,upregulated p-AMPK,Shank 3,PSD 95,NR^(2)A,NR^(2)B,NR1 protein expressions,and downregulated p-mTOR protein expression.CONCLUSION Sijunzi Decoction can improve the insulin sensitivity,the neuronal cell damage,and thus the cognitive dysfunction in DM mice.And the mechanism may be related to the improvement of their synaptic protein expression,hippocampal synaptic homeostasis,and synaptic function through the AMPK/mTOR signaling pathway.