Tau蛋白过度磷酸化对2型糖尿病所致神经纤维化的影响

Effect of Tau protein hyperphosphorylation on nerve fibrosis induced by type 2 diabetes mellitus

目的观察胰岛素抵抗、高血糖和罗格列酮对大鼠认知功能、海马β样淀粉蛋白(Aβ)、Tau蛋白总量及其磷酸化的影响,探讨2型糖尿病患者神经纤维化的机制。方法将48只Sprague-Dawley(SD)大鼠随机分为6组(每组8只):普食+马来酸罗格列酮组、普食+无治疗组、高脂高糖高蛋白(HFD)+马来酸罗格列酮组、HFD+无治疗组、HFD+链脲佐菌素(STZ)+马来酸罗格列酮组、HFD+STZ+无治疗组。通过Morris水迷宫测试大鼠的认知功能。采用高效液相色谱法测定大鼠海马组织中谷氨酸(Glu)水平,ELISA法测定总Tau蛋白(Tau5)和p-PHF1^(Ser396/404)、p-AT8^(Ser199/202)、p-12E8^(Ser262)水平。结果普食+马来酸罗格列酮组和普食+无治疗组的Morris水迷宫逃避潜伏期(EL)均显著短于HFD+STZ+马来酸罗格列酮组(P值均<0.05),空间探索时间(SET)均显著长于HFD+STZ+马来酸罗格列酮组(P值均<0.05);普食+马来酸罗格列酮组的EL显著短于HFD+马来酸罗格列酮组(P<0.05),SET显著长于HFD+马来酸罗格列酮组(P<0.05);HFD+无治疗组的EL显著长于HFD+马来酸罗格列酮组(P<0.05),SET显著短于HFD+马来酸罗格列酮组(P<0.05);HFD+STZ+无治疗组和HFD+无治疗组的EL均显著长于普食+无治疗组(P值均<0.05),SET均显著短于普食+无治疗组(P值均<0.05)。HFD+STZ+马来酸罗格列酮组的Glu水平显著高于普食+无治疗组和普食+马来酸罗格列酮组(P值均<0.05);HFD+马来酸罗格列酮组的Glu水平显著低于HFD+无治疗组(P<0.05),显著高于普食+马来酸罗格列酮组(P<0.05);普食+无治疗组的Glu水平显著低于HFD+STZ+无治疗组和HFD+无治疗组(P值均<0.05)。HFD+STZ+马来酸罗格列酮组的总Tau蛋白、p-PHF1^(Ser396/404)、p-AT8^(Ser199/202)和p-12E8^(Ser262)水平均显著高于普食+无治疗组和普食+马来酸罗格列酮组(P值均/<0.05);HFD+马来酸罗格列酮组的总Tau蛋白、p-PHF1^(Ser396/404)、p-AT8^(Ser199/202)和p-12E8^(Ser262)水平均显著低于HFD+无治疗组(P值均<0.05),均显著高于普食+马来酸罗格列酮组(P值均<0.05);普食+无治疗组的总Tau蛋白、p-PHF1^(Ser396/404)、p-AT8^(Ser199/202)和p-12E8^(Ser262)水平均显著低于HFD+STZ+无治疗组和HFD+无治疗组(P值均<0.05)。结论胰岛素抵抗和血糖水平升高可能是2型糖尿病时海马Tau蛋白过度磷酸化的原因,罗格列酮可缓解这一过程。

Objective To observe the effect of insulin resistance, high blood sugar and rosiglitazone on the cognitive ability of rats, the content of A β and the phosphorylation of Tau protein in the hippocampus, so as to investigate the mechanism of neural fibrosis of patients with type 2 diabetes. Methods Forty-eight Sprague- Dawley （SD） rats were divided into 6 groups（n = 8）. Group A was given ordinary food and maleic acid rosiglitazone. Group B was given ordinary food but no drugs. Group C was given high fat and sugar diet （HFD） and maleic acid rosiglitazone. Group D was given the HFD but no drugs. Group E was given the HFD, streptozoucin （STZ） and maleic acid rosiglitazone. Group F was given the HFD and STZ but no drugs. The cognitive ability of rats was detected by Morris water maze test. The concentration of glutamic acid （Glu） was determined by high performance liquid chromatography （HPLC）. The expression of Tau protein （Tau 5）, p-PHF1^Ser396/404、p-AT8^Ser199/202 and p-12E8^Ser262 were determined by enzyme linked immunosorbent assay （ELISA）. Results The escape latency （EL） values of groups A and B were significantly lower than that of group E （both P〈0.05）, but the space exploration time （SET） values of groups A and B were significantly higher than that of group E （both P〈 0.05）. The EL value of group A was significantly lower than that of group C （P〈0.05）, but the SET value of group A was significantly higher than that of group C （P〈0.05）. The EL value of group D was significantly higher than that of group C （P〈0.05）, but the SET value of group D was significantly lower than that of group C （ P〈 0.05）. The EL values of groups F and D were significantly higher than that of group B （both P〈0.05）, but the SET values of groups F and D were significantly lower than that of group B （both P〈0.05）. The Glu level of group E was significantly higher than that of groups A and B （both P〈0.05）. The Glu level of group C was significantly lower than that of group D （P〈0.05）, but significantly higher than that of group A （P〈0.05）. The Glu level of group B was significantly lower than that of groups F and D （both P〈0. 05）. The levels of total Tau, p-PHF1^Ser396/404、p-AT8^Ser199/202 and p-12E8^Ser262 of group E were significantly higher than those of groups A and B （all P〈0. 05）. The levels of total Tau protein,p-PHF1^Ser396/404、p-AT8^Ser199/202 and p-12E8^Ser262 of group C were significantly lower than those of group D （all P〈0.05）, but significantly higher than those of group A （all P〈 0.05）. The levels of total Tau protein, p-p-PHF1^Ser396/404、p-AT8^Ser199/202 and p-12E8^Ser262 of group B were significantly lower than those of groups F and D （all P〈0.05）. Conclusion Insulin resistance and increased serum glucose concentration may cause hyperphosphorylation of Tau protein in the hippocampus as type 2 diabetes occurs. Rosiglitazone can reduce the expression of Tau protein phosphorylation in hippocampus.