糖尿病大鼠认知功能与海马组织β-淀粉样蛋白、肿瘤坏死因子α表达相关性的研究

A study on correlation of cognitive function and expression with beta-amyloid, tumor necrosis factor alpha in hippocampus of diabetic rats

目的 分析糖尿病大鼠认知功能与海马组织β-淀粉样蛋白（Aβ）、肿瘤坏死因子α（TNF-α）表达的相关性,探讨炎症反应在糖尿病脑病（diabetic encephalopathy,DE）发病机制中的作用.方法 雄性8w龄SD大鼠30只随机分为对照组和糖尿病组,糖尿病组高脂饮食喂养4m后按30 mg/kg腹腔注射链脲佐菌素建立2型糖尿病大鼠模型,观察不同阶段动物的体重、空腹血糖（fasting blood glucose,FBG）、空腹血清胰岛素（fasing serum insulin,FSI）,并计算胰岛素敏感指数（insulin sensitivity index,ISI）.实验末行水迷宫测试评估两组大鼠认知功能;酶联免疫吸附测定法、蛋白质印迹法和免疫组织化学法检测观察大鼠海马组织Aβ、TNF-α的表达,并与水迷宫测试结果进行相关性分析.结果 糖尿病组大鼠在目标象限的探索时间较对照组缩短（P＜0.01）,原平台穿越次数较对照组减少（P＜0.01）,糖尿病组Aβ和TNF-α表达较对照组升高（均P＜0.01）,免疫组织化学染色观察糖尿病组海马组织Aβ、TNF-α阳性表达明显增加.相关性分析显示Aβ、TNF-α与目标象限探索时间及原平台穿越次数均呈负相关.结论 糖尿病大鼠认知功能受损,可能与Aβ、TNF-α的表达增加相关,这些因素可能参与DE的发病过程.

Objective To analyze the correlation of cognitive function and expression with beta-amyloid （Aβ）, tumor necrosis factor alpha （ TNF-α ） in hippocampus of diabetic rats, and to assess the role of inflammation in the possible pathogenesis of diabetic encephalopathy （DE）. Methods 30 male SD rats （8 weeks old） were randomly divided into control group and diabetes mellitus group. After 4 weeks of high fat diet feeding, diabetes mellitus group were injected intraperiton- eally with streptozotocin at a dose of 30 mg/kg to establish the type 2 diabetic rat model. Body weight, fasting blood glucose （FBG）, fasting serum insulin （FSI） were detected at various time intervals, and insulin sensitive index （ISI） was calculated. At the end of the experiment, cognition of all the rats were evaluated according to a water maze test. The expression of Aβ and TNF-α in hippocampus were detected and observed by enzyme linked immunosorbent assay （ ELISA ）, Western blotting and immunohistochemistry, and a correlation analysis was conducted with the water maze test. Results Time spent in the target quadrant in diabetes mellitus group was shorter than control group （P〈0.01）, more over, the frequency of crossing the original platform site was less （P〈0.01）. Compared with control group, the expression of A~ and TNF-α were higher in diabetes mellitus group （ BothP〈0.01 ）. The positive expression of Aβ and TNF-α were observed obviously increased in diabetes mellitus group by immunohistochemistry. The correlation analysis showed that the expression of Aβ and TNF-α were both negatively correlated with the time spent in the target quadrant and the frequency of crossing the original platform site. Conclusion The cognitive impairment in diabetic rats is possibly related to the increased expression of Aβ and TNF-α, which may be involved in the pathomechanism of DE.