mTOR信号通路在痛相关海马突触可塑性中的作用

Recent studies indicate that mTOR, as an important regulating gene, controls cellular growth and proliferation and formation of synaptic plasticity by regulating synthesis of many kinds of proteins. Therefore, the study of revealing the key roles of mTOR in the generation of central and peripheral sensitization of pain becomes a hot spot.Our previous work proved that peripheral persistent nociception has great impact upon the higher brain structures，which not only temporal, but also lead to spatial plasticity of synaptic interconnections and functions in the hippocampal formation by multi-electrode array recording system. Moreover, two kinds of group I metabotropic glutamate receptor (mGluR1 and 5) take part in this process was demonstrated . Based on the previous work in our lab, we make further exploration in the mechanisms of mTOR signaling pathway in the persistent pain-associated spatial and temporal changes in entorhinal-hippocampal synaptic plasticity. The experiment of this study design as follows:(1) Distribution of mTOR and phospho-mTOR in rat hippocampal formation will be observed by immunofluorescence double labeling of mTOR in the DG and CA1 area.(2) Activation of mTOR signaling pathway in rat hippocampus tissues induced by peripheral persistent pain will be detected by western blotting.(3) We will use multi-electrode array recording system(MED-64) to demonstrate whether mTOR play an important role in the temporal and spatial synaptic plasticity including connection and function in entorhinal area-hippocampus induced by peripheral persistent pain. (4) By using PSN, PWMT, PWTL, morris water maze and open field test to explore the alterations of memory , emotion and pain-related behaviors of the rats under the persistant inflammatory pain condition. This research expects to provide a new clinical treatment strategy for the chronic pain patients who are sufferring from the cognition and mental disorders.

哺乳动物雷帕霉素靶蛋白(mTOR)是一种重要的调节蛋白，可调控翻译元件的生物合成。mTOR依赖的局部蛋白合成在慢性痛所致外周伤害性感受器的敏化及脊髓背角神经元可塑性中起关键作用,但在痛相关海马突触可塑性中的作用尚待阐明。前期工作证实，外周持续性伤害可诱导海马结构发生突触效能和空间联系的可塑性改变。我们推测，mTOR 信号通路可被持续性痛激活,通过局部蛋白质翻译机制调控大鼠海马突触可塑性。本课题采用分子生物学、电生理以及行为学方法进行以下研究：(1)明确mTOR信号通路在海马结构中的分布特点；(2)揭示持续性痛刺激条件下mTOR 信号通路mRNA和蛋白表达的变化规律；(3)在神经元网络水平上，明确mTOR信号通路是否介导持续性痛所致海马突触可塑性改变；(4)进一步验证海马mTOR信号通路介导大鼠痛相关行为的改变。为临床上治疗慢性痛患者所伴发的认知和精神障碍提供新的靶点。

哺乳动物雷帕霉素靶蛋白(mTOR)是一种重要的调节蛋白，可调控翻译元件的生物合成。mTOR依赖的局部蛋白合成在慢性痛所致外周伤害性感受器的敏化及脊髓背角神经元可塑性中起关键作用,但在痛相关海马突触可塑性中的作用尚待阐明。本课题主要研究内容：mTOR信号通路在正常大鼠海马结构中的表达和分布；海马mTOR信号通路相关分子蛋白在大鼠持续性痛产生和维持过程中的表达变化；mTOR信号通路介导持续性痛致海马结构突触可塑性的时空改变；海马mTOR信号通路介导大鼠痛相关行为学改变。重要结果：1. mTOR 及磷酸化mTOR主要分布于海马结构齿状回（DG）区的颗粒细胞中以及CA1 区椎体细胞中。2. 在外周持续性痛刺激条件下海马组织中mTOR 信号通路被激活并具有时程性，并且该通路的激活与外周伤害性信息的传入密切相关。3. mTOR 信号通路的激活在外周持续性痛导致内嗅区－海马结构突触联系和功能发生时间和空间的可塑性改变中起重要作用。4. mTOR信号通路参与外周持续性痛刺激诱发的大鼠痛行为的改变。关键数据：1. mTOR及磷酸化mTOR主要分布于海马结构齿状回（DG）区的颗粒细胞中以及CA1 区椎体细胞中。2. 经过致炎处理后海马组织中的磷酸化mTOR 的相对表达量在蜜蜂毒致炎处理2 h、4 h、8 h 后明显增高；磷酸化S6K 的相对表达量在蜜蜂毒致炎处理2 h、4 h、8 h 后明显增高。3. RAPA+BV 组和DMSO+BV对照组相比标准化的fEPSP 幅度显著降低。并且RAPA+BV 组DG 区LTP 的幅度从TBS 后80 min 显著降低，一直持续至2 h；CA1 区LTP 的幅度从TBS 后90 min 显著降低，一直持续至2 h。从幅度和斜率的Input-Output 曲线看，RAPA+BV 组与DMSO+BV 对照组相比,在DG 区及CA1 区都有明显的右移。4. DMSO+BV处理组大鼠在中央区域和四边区域的比值低于正常组和RAPA+BV 处理组大鼠，而在四角区域的比值明显高于正常组和RAPA+BV 处理组大鼠。科学意义:1.本课题揭示持续性痛刺激mTOR信号通路介导大鼠海马突触可塑性的改变，为临床治疗慢性痛患者的负性情绪提供新思路。2.揭示了mTOR信号通路在痛相关海马突触可塑性的作用，为慢性疼痛的基因治疗提供新靶点，具有潜在的临床应用前景。