Wang Xiao-Chuan, Zhang Jing, Yu Xian, Han Liu, Zhou Zhen-Tao, Zhang Yao, Wang Jian-Zhi
Department of Pathophysiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Sheng Li Xue Bao. 2005 Feb 25;57(1):7-12.
Hyperphosphorylated microtubule-associated protein tau is the major protein component of neurofibrillary tangles in the brain of patients with Alzheimer's disease (AD). Until now, there is no effective cure to arrest this hyperphosphorylation. The present study was designed to explore the in vivo preventive effect of melatonin on Alzheimer-like tau hyperphosphorylation. Isoproterenol, a beta-receptor agonist, was used to induce tau hyperphosphorylation, and for preventive effect of melatonin, the rats were injected intraperitoneally with melatonin for 5 d before hippocampi infusion of isoproterenol. The level of tau phosphorylation was detected by Western blot and immunohistochemistry using sites specific antibodies (PHF-1 and Tau-1), and it was normalized by non-phosphorylation dependent total tau antibody (111e). The results by Western blot showed that the immunoreaction of tau at PHF-1 epitope was enhanced, and the reaction at Tau-1 epitope was weakened significantly at 48 h after injection of isoproterenol, suggesting hyperphosphorylation of tau at Ser 396/Ser 404 (PHF-1) and Ser199/Ser 202 (Tau-1) sites. Similar results were observed by immunohistochemistry staining, in which hyperphosphorylated tau was mainly detected in mossy fibers of hippocampal CA3 region. Pre-injection of rats with melatonin intraperitoneally arrested effectively the isoproterenol-induced tau hyperphosphorylation at both Tau-1 and PHF-1 sites, implying the preventive effect of melatonin in Alzheimer-like tau hyperphosphorylation.
过度磷酸化的微管相关蛋白tau是阿尔茨海默病（AD）患者大脑中神经原纤维缠结的主要蛋白质成分。到目前为止，尚无有效的疗法来阻止这种过度磷酸化。本研究旨在探讨褪黑素对阿尔茨海默病样tau过度磷酸化的体内预防作用。使用β受体激动剂异丙肾上腺素诱导tau过度磷酸化，为研究褪黑素的预防作用，在向海马体注射异丙肾上腺素前5天，给大鼠腹腔注射褪黑素。使用位点特异性抗体（PHF-1和Tau-1）通过蛋白质免疫印迹法和免疫组织化学法检测tau磷酸化水平，并用非磷酸化依赖性总tau抗体（111e）进行标准化。蛋白质免疫印迹法结果显示，注射异丙肾上腺素后48小时，tau在PHF-1表位的免疫反应增强，而在Tau-1表位的反应显著减弱，表明tau在Ser 396/Ser 404（PHF-1）和Ser199/Ser 202（Tau-1）位点发生了过度磷酸化。免疫组织化学染色也观察到类似结果，其中过度磷酸化的tau主要在海马CA3区的苔藓纤维中检测到。预先给大鼠腹腔注射褪黑素可有效阻止异丙肾上腺素诱导的tau在Tau-1和PHF-1位点的过度磷酸化，这意味着褪黑素对阿尔茨海默病样tau过度磷酸化具有预防作用。
