叶酸联合维生素B_(12)对糖尿病大鼠记忆能力及Tau蛋白过度磷酸化影响

Supplementation of folic acid and vitamin B_(12) prevents the performance in Morris water maze and Alzheimer-like hyperphosphorylation of tau in diabetes mellitus rats

目的:研究糖尿病大鼠脑内各磷酸化位点的变化,探讨叶酸联合维生素B12对糖尿病模型大鼠学习记忆能力及脑内tau蛋白过度磷酸化的影响。方法:糖尿病大鼠用链脲佐菌素腹腔注射制备,实验组予以叶酸联合维生素B12干预。采用Morris水迷宫检测各组大鼠空间记忆及学习能力;用蛋白免疫印迹法观察各组大鼠额叶皮层脑组织总tau、tau部分位点磷酸化变化。结果:(1)Morris水迷宫结果:1型、2型糖尿病组大鼠逃避潜伏期较对照组及单纯药物干预组明显延长(P<0.05),使用叶酸联合维生素B12干预相应模型组后均能显著改善(P<0.05)。(2)叶酸联合维生素B12对糖尿病大鼠脑内tau蛋白过度磷酸化影响:各组大鼠额叶皮层脑组织总tau蛋白含量比较差异无统计学意义(P>0.05);1型、2型糖尿病组大鼠额叶皮层脑组织tau蛋白在丝氨酸396/404位点、苏氨酸205位点、苏氨酸212位点的磷酸化水平较对照组及单纯药物干预组明显增高,差异有统计学意义(P<0.05),使用叶酸联合维生素B12干预后,以上位点磷酸化水平均有明显下降(P<0.05)。结论:糖尿病大鼠脑组织内tau蛋白出现阿尔茨海默病样过度磷酸化;叶酸联合维生素B12干预后可逆转病变,发挥保护脑组织作用。

Object ive：To investigate the changes of hyperphosphorylation of tau in the brain of diabetes mellitus model rats and to determine whether the supplementation of folic acid and vitamin B12 prevents the AD-like hyperphospho_rylation of tau in the diabetes rat brain and leaning and memory deficits, which may provide a theory reference for the clin_ical application. Methods：Diabetes mellitus rats were induced by intraperitoneal injection Streptozocin, and the treatment groups were treated with folic acid/vitamineB12. The spatial memory and learning ability was tested by the Morris water maze. Western blot was used to detect the level of some proteins such as total tau and phosphorylation of tau at some sites. Results：（1）Results of Morris water maze：both type I diabetes mellitus（T1DM） and type II diabetes mellitus（T2DM） rats had much longer escape latency （P〈0.05）, and the time of escape latency was significantly shortened in the diabetes rats which received the supplementation of folic acid and vitamin B12（P〈0.05）.（2）Effect of supplementation of folic acid and vitamin B12 on the abnormal hyperphosphorylation of tau in diabetes mellitus rats： the level of tau in the frontal cortex of brain had no difference （P〉0.05）;the levels of phosphorylated tau at serine 396/404, threonine 205 and threonine 212 were increased in both T1DM group and T2DM group（P〈0.05）, suggesting the hypeprhosphorylation of tau in diabetes rat brain. Supplementa_tion of folic acid and vitamin B12 attenuated hyperphosphorylation significantly at the above sites （P〈0.05）. Conclusion： It was showed in the test that the spatial memory and learning ability of T1DM group and T2DM rats was impaired signifi_cantly, and Tau in the brain of DM model rats was hyperphosphorylated. Both of them were improved by supplementation of folic acid and vitamin B12.