牛磺酸对慢性应激大鼠海马神经再生的作用及机理研究

Chronic psychological and physiological stess which was induced by the quick pace of mordern life could induce mental disease such as hypomnesia and depression by damaging hippocampal neurogenesis.Taurine was known to be necessary in the neurodevelopment of young animals and could promote the proliferation of various kinds of stem cells from young animals. Our previous research found that taurine could improve learning ability and memory of adult rats by improving the structure of neuron and synapses and regulating neurotransmitters.Further research proved that taurine could counteract the suppressive effects of lipopolysaccharide on neurogenesis in the hippocampus of rats by increasing the proliferation of neuronal precursor cells in the Dentate Gyrus of hippocampus. Whereas the effects and mechanisms of taurine on chronic stress animals is still unknown. The present research was conducted to clarify the effects and its mechanisms of taurine on neurogenesis in the hippocampus by examining the learning ability, memory and anxiety behavior of rats under chronic stress conditons. Neurotransmitters and hormons participated in the process of neurogenesis in blood and hippocampus were analyzed by way of High Performance Liquid Chromatography and ELISA. Expression levels of protein markers in different stages of neurogenesis were detected by immunohistochemistry, gene and protein expression of growth factors, neurotrophic factors and signal pathway related to neurogenesis were detected by Real-Time PCR and Western-blot respectively.The present study aimed to provide valubale fundations for the prevention and cure of diseases induced by the reduction of neurogenesis, and develop the new functions of taurine in nervous system.

现代快节奏的工作生活压力等慢性应激导致的海马神经再生障碍已被证明是引起记忆减退、抑郁等精神疾病的主要原因之一。牛磺酸是幼龄动物神经发育的必需物质，并可促进多种干细胞增殖。课题组研究发现，牛磺酸可改善成年大鼠海马神经元结构和功能；并初步证明可抑制脂多糖导致的大鼠海马神经再生障碍，促进神经干细胞增殖，但其对慢性应激海马神经再生的确切作用及机制尚不明确。本项目拟制备慢性应激大鼠模型结合海马神经干细胞培养，观测大鼠学习记忆及焦虑行为，应用免疫组化技术检测神经再生各阶段标记物的表达，评价牛磺酸对慢性应激导致神经再生障碍的保护作用；采用高效液相电化学和ELISA法检测神经递质及激素水平，Real-Time PCR、Western-blot技术检测海马神经生长和营养因子及相关信号通路各因子的基因、蛋白表达水平，阐明牛磺酸对慢性应激大鼠海马神经再生的调控机制，为神经再生障碍相关疾病的防治提供参考。

随着生活节奏的加快，社会竞争日益激烈，工作、生活的压力带给人们严重的慢性应激，造成机体神经内分泌系统紊乱，损伤大脑海马神经元，抑制神经再生，导致学习记忆能力减退，诱发抑郁症等神经退行性疾病，危害人们的健康。牛磺酸是中枢神经系统含量最丰富的游离氨基酸之一，具有神经保护作用。本项目开展牛磺酸对慢性应激大鼠海马神经元的保护作用及其机制的研究，旨在为应用牛磺酸防治慢性应激导致的相关神经疾病提供有价值的参考。. 给予成年雄性Wistar大鼠28天慢性不可预见应激，并结合孤笼饲养制备慢性应激模型，同时每日腹腔注射200及500 mg/kg 牛磺酸，每周测量体重及糖水消耗率，造模结束进行水迷宫及旷场试验，检测牛磺酸对慢性应激大鼠学习记忆能力、焦虑恐惧行为的影响；采集血液及海马，ELISA法测定5-羟色胺(5-HT)、去甲肾上腺素(NE)、多巴胺(DA)、皮质醇(CORT)、谷氨酸(Glu)、白细胞介素-1β (IL-1β)、肿瘤坏死因子(TNF-α)的含量；免疫组织化学染色法检测海马齿状回神经再生标记物Ki67的表达；提取海马RNA与总蛋白，采用RT-PCR和Western Blotting法检测海马成纤维生长因子-2(FGF-2)、血管内皮生长因子(VEGF)、脑源性神经营养因子(BDNF)、Notch信号通路相关因子的mRNA和蛋白表达水平。同时体外分离培养原代海马神经干细胞，检测牛磺酸对神经干细胞增殖的影响。. 结果表明：牛磺酸可改善慢性应激导致的大鼠学习记忆能力下降，缓解焦虑恐惧情绪；显著增加慢性应激大鼠海马的Ki67表达；减少慢性应激大鼠血液及海马CORT、Glu、TNF-α、IL-1β的含量，升高NE、DA及5-HT水平；上调慢性应激大鼠海马BDNF、FGF-2、VEGF及Notch信号通路各因子的基因及蛋白表达；并增加体外培养的海马神经干细胞的增殖。说明牛磺酸可通过调节HPA轴，维持神经内分泌系统的正常功能，减少炎性因子的释放，减轻慢性应激对大鼠海马神经元的损伤；同时牛磺酸可通过上调神经营养因子的表达，激活Notch信号通路，促进海马神经再生，进而减轻慢性应激导致的大鼠行为学障碍。

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