糖尿病脑病机理的再探讨及APP17肽的作用

RE\|EXAMINATION OF PATHOGENESIS OF DIABETIC ENCEPHALOPATHY AND THE EFFECTS OF APP17\|MER PEPTIDE

目的 检测糖尿病小鼠脑内Tau蛋白不同位点的磷酸化状态及 β淀粉样肽表达的改变 ,进一步探讨糖尿病脑病的机理并观察APP17肽的作用。 方法 用链脲佐菌素诱发小鼠糖尿病模型 ,并皮下注射APP17肽进行保护。 4周后 ,取小鼠脑组织做BT 2、Rllle免疫组织化学染色。另一部分小鼠断头取脑 ,分离海马 ,做Tau 1、AT 8、Aβ1 16和管蛋白 (tubulin)抗体蛋白免疫印迹。 结果 糖尿病小鼠脑海马神经元内正常Tau蛋白含量减少 ,Tau蛋白 192 2 0 2位点及 194 198位点过度磷酸化 ,而Thr2 31和Thr181位点未被磷酸化 ;管蛋白的表达明显减少 ,而APP的表达则增多。用APP17肽对糖尿病小鼠进行保护后 ,Tau蛋白的磷酸化程度降低 ,APP和Tubulin的表达恢复到接近正常水平。 结论 糖尿病小鼠脑内Tau蛋白过度磷酸化、tubulin表达减少 ,微管结构受损 ,同时APP表达增加造成Aβ含量增多 ,引起神经元损害。对糖尿病小鼠应用APP17肽使Tau保持磷酸化程度、APP及tubulin表达接近正常 ,因此 。

Objective To investigate the phosphorylated state of Tau and the changes of Aβ in the brain of diabetic mice, so as to explore the possible pathogenesis of diabetic encephalopathy and observe the effects of APP17\|mer peptide. APP17\|mer peptide is the 319\|335 peptide sequence of β amyloid precursor protein(APP),and can enhance neuronal survival and growth of axonal processes. Methods Mouse diabetic model was produced with streptozotocin,and APP17\|mer peptide was injected subcutaneously as a protective.Four weeks later,cryostat sections of mice brain were prepared and immunohistochemically stained for BT\|2, Rllle.Meanwhile,the brains of some mice were taken and the hippocampus was insolated to determine protein concentration by Western blot.The protein sample was immunoblotted with antibodies to Tau\|1,AT\|8,Aβ1\|16 and tubulin respectively. Results The expression of APP was increased. The content of normal Tau was reduced and Tau protein was hyperphosphorylated at 199/202 and 194/198 sites.But Thr231 and Thr181 sites of Tau protein was not hyperphosphorylated.The use of APP17\|mer peptide normalized the expression of APP and tubulin and lowered the phosphorylated state of Tau. Conclusion Tau protein is hyperphosphorylated in the brains of diabetic mice.The hyperphosphorylation of Tau protein causes it to lose its activity to promote microtubule assembly which is also damaged by the reduced expression of tubulin.The increased expression of APP may enhance the amount of Aβ,which damages neurons very seriously. App17\|mer peptide can improve the expression of tubulin, normalize APP expression, and lows the phosphorylated state of Tau protein in diabetic mice. [