少突胶质细胞与神经元之间能量代谢偶合的调控机制研究

The oligodendrocytes have the function of transporting energy substances to the neuron axons, and it is correlated with energy metabolism coupling between oligodendrocyte and neuron. The mechanism of energy metabolism coupling between oligodendrocyte and neuron are because the oligodendrocytes produce high concentration of lactate through the glycolysis, then transmit them to the axons enwrapped by themselves. According to this basement, we hypothesize that glutamate releasing from neurons activate the NMDA receptor in oligodendrocyte myelin, and then regulate the expression and activity of monocarboxylate transporter 1 (MCT1). The expression of MCT1 should be stimulated by the tumor-inhibiting factor p53 and other related factors, and then they should be regulated by cAMP signal pathway and the synergistic action of chaperones from CD147 family, this process will improve the function of MCT1 and transport more energy substance to neurons. In order to elucidate these questions, we will carry out this item. By using molecular biological, morphological electrophysiological and praxiological techniques, at first, we will observe the expression of MCT1 and their regulation mechanism. Then, we will study the signal pathway which regulate the function of MCT1; we will also identify the possible chaperone(s) which co-operate with MCT1, and co-localized of MCT1 and the possible chaperone(s) and their possible regulation molecules during the normal development and aging; at the same time, we will also pay attention to the neuron signals of glutamate through NMDA receptor in oligodendrocyte. At last, we will observe the effects on the neuron and axon structures and the whole function after changing the functional status of MCT1. These results will conduce to interpret the regulation mechanism of energy metabolism coupling between oligodendrocyte and neuron, and provide a new thinking and strategy to prevent and cure the energy dysmetabolism related neurodegeneration diseases.

少突胶质细胞(OL)具有向神经元轴突提供能量物质的功能，这与OL-神经元两类细胞之间的能量代谢偶合密切相关，其机制是OL产生乳酸盐并由特异性转运体MCT1传递给轴突。我们在此基础上提出假说：神经元的功能活动通过谷氨酸递质作用于OL髓鞘上的NMDA受体，调节OL内的肿瘤抑制因子p53等促进MCT1基因表达，进一步通过OL内cAMP信号途径的调节和伴侣分子CD147家族蛋白的协同作用，增加MCT1上膜和功能活性，保障神经元的能量供应。为了证实这一假说，拟采用分子生物学、形态学、电生理学和行为学等技术，明确OL自身调控MCT1的基因表达和功能活性的分子，并确定神经元对OL中MCT1基因表达和功能活性的调节途径，进而证实OL中MCT1功能异常对神经网络和整体功能的影响。研究结果将从能量代谢耦合调控机制的角度阐明OL与神经元两类细胞之间的相互作用，为能量代谢障碍相关的神经退行性疾病提供新的防治思路。

证据表明，少突胶质细胞（OL）由特异性单羧酸转运体-1（MCT1）将乳酸盐传递给神经元轴突。毫无疑问，这一能量供应途径障碍会导致神经元结构与功能异常，甚至引发神经退行性病变，因此，深入研究OL向神经元轴突供应能量具有重要意义。.本项目采用了免疫荧光多重标记、Western blot、体外细胞培养、行为学等多种技术手段，研究了MCT1、MCT2和MCT4在不同发育阶段、在学习记忆相关脑区、不同种类细胞内的表达和功能特点，并比较了在正常和阿尔兹海默症（AD）的差异；另外，研究了甲状腺激素（TH）和一氧化氮（NO）对OL和髓鞘的作用特点和可能机制。.研究结果显示：①正常出生后MCT1表达水平逐渐升高，第5周达高峰，随后一直到第12月均逐渐下降。MCT1主要定位于OL及其形成的髓鞘，MCT2主要定位于神经元，MCT4主要定位于星形胶质细胞。MCT1水平的变化趋势与神经元数量、OL数量的变化趋势完全一致，具有明显的相关性。表明OL对乳酸盐的转运障碍可能是神经退行性疾病的始动因素之一。②与野生型相比，AD模型小鼠大脑皮层和海马CA1区MCT1、2、4的含量均明显减少，乳酸脱氢酶A和B（LDHA/LDHB）的比率明显上升，但星形胶质细胞数量是增加的。表明AD破坏了神经元和胶质细胞的能量运输平衡，神经元可能自身具有一定的代偿能力，有利于神经元结构与功能的维持。③Aβ1-42脑内注射可明显降低小鼠体重、抑制平衡运动能力和破坏胼胝体区域的髓鞘，还可抑制体外培养的少突胶质细胞前体细胞（OPCs）的生长。表明Aβ显著影响髓鞘形成和功能。④TH和NO参与了内源性OPCs的调节和髓鞘形成的作用。表明TH和NO可能在神经退行性疾病的防治方面具有应用前景。.综上，本项目系统研究OL向神经元运输乳酸盐的功能及其调控机制，为OL与神经元两类细胞之间的相互作用提供新的实验证据，有可能为能量代谢障碍相关的神经退行性疾病防治提供新的思路和策略，从而具有广阔的应用前景。