Humanin在老年性痴呆发病过程中抗衰老作用的研究

The appearance of amyloid senile plaques( SP ), neurofibrillary tangles ( NFT ) and the progressive neuronal defects in the cerebral cortex and hippocampus is the main characteristic pathological change of Alzheimer's disease ( AD ).The aggregation, fibrosis, deposition of Aβin the brain are the important pathological basis leading to AD. Humanin is currently considered as the unique short peptide which can inhibit both Aβ nerve poison and a variety of FAD gene mutation and APP antibodies induced neurotoxic effects . Central direct injection of Humanin can induce the damage of nerve tissue.While Humanin cannot pass through the blood-brain barrier by intravenous injection, which bringing the high cost of chemical synthesis.Using chimeric gene technique，this study design and construct a fusion peptide gene NT4-Humanin-AntcDNA which can pass through the blood-brain barrier, and the fusion peptide cDNA expression cassette is inserted into the adeno-associated virus ( AAV ) vectors, thus construct recombinant AAV vectors which then transfected into the nasal mucosa of APP transgenic AD mice model, whose cells continuous secret and express Humanin-Ant fusion peptide carrying penetrating peptide, thereby entering the brain by the nose-brain pathway. Then through the behavioral evaluation and immunopathological methods ,we aim to observe the anti-aging effect of Humanin-Ant-AAV in the pathogenesis of Alzheimer's disease.

老年性痴呆（AD）的病理改变以大脑皮层、海马等出现淀粉样老年斑块（SP）、神经元纤维缠结（NFT）、神经元进行性缺失为主要特征。Aβ在脑内聚集、纤维化、沉积等是导致AD的重要病理学基础。Humanin目前认为是唯一既能抑制Aβ神经毒性又能抑制各种FAD基因突变和APP抗体诱发的神经毒性作用的短肽。中枢直接注射Humanin会引起神经组织损伤；而静脉注射难以通过血脑屏障，且化学合成成本高。本研究利用基因嵌合技术设计并构建能通过血脑屏障的融合肽目的基因NT4-Humanin-AntcDNA，并将融合肽的cDNA表达盒插入腺相关病毒（AAV）载体中，构建重组腺相关病毒载体，然后转染APP转基因AD模型小鼠的鼻粘膜，使其持续分泌表达携带穿膜肽的Humanin-Ant融合肽，从而使之通过鼻脑通路入脑，继而用行为学评定、免疫病理等方法观察Humanin-Ant-AAV在老年性痴呆发病过程中抗衰老作用。

阿尔茨海默病（Alzheimer's disease, AD），是以进行性记忆减退、认知障碍、人格改变为主要临床表现的一种神经系统变性疾病，是临床最常见的老年痴呆类型。如何有效地防止和（或）减少 Aβ在脑内的聚集和老年斑形成以及拮抗 Aβ神经毒性作用，是从根本上防治 AD 的重要策略之一。采用基因治疗的手段对AD进行防治目前在国内外尚处于起步阶段。本研究首先通过体外合成Humanin-Ant融合肽，观察Humanin-Ant融合肽对Aβ所造成PC12细胞毒性的保护作用；之后利用基因嵌合技术设计构建携带NT4-Humanin重组腺相关病毒载体，并转染AD模型大鼠的鼻黏膜，使之通过鼻脑通路入脑，继而用行为学方法评定NT4-Humanin-Ant-AAV对AD模型大鼠学习记忆行为的影响。已得到的结果表明：Humanin-Ant融合肽对Aβ所造成PC12细胞毒性具有保护作用，包括降低细胞乳酸脱氢酶释放率和早期凋亡发生率；NT4-Humanin-Ant-AAV可通过鼻黏膜通路入脑，可提高AD大鼠的学习能力，并在一定程度上增强AD大鼠的记忆能力。本研究为 AD 等神经退行性疾病的预防和治疗提供潜在的方法和思路。