BDNF与NMDAR的相互调控在不同条件微波辐射致学习记忆障碍中的作用研究

Research on health effects of microwave radiation has grown exponentially and numerous in vivo and in vitro studies have been found that microwave might induce the impairment of learning and memory ability. In our previous studies, we found that it was discrepant in the change of NMDAR expression after different microwave exposure which resulted in the impaiment of learning and memory ability. But it was not calrified that the different radiation resulted in the different biological effects by the role of NMDAR. We also found that microwave radiation resulted in the abnormalities of the NMDARs-PSD95-CaMKII pathway which might contribute to the inhibition of synaptic transmission by influencing synaptic structure, synapsin I expression and phosphorylation, and neurotransmitter release, but the mechanism was still unclear. So in the study, long-term exposure of low radiation dose and single exposure of high radiation dose were used to establish the animal model of learning and memory ability impaiment and neuron model of synaptic transmission injury. The role of different microwave exposure on BDNF and NMDAR was studied by the detection of expression and phosphorylation of BDNF, TrkB, NMDAR and the associated signal pathway moleculars.Then exogenous BDNF or TrkB inhibitor or kinase inhibitors were used to detect the effect on the expression and phosphorylation of NMDAR and the synaptic transmission. Finally, NMDAR agonist or antagonist and intervetions of other links used, we observed the transcription and translation of BDNF, the release of presynaptic vesicles after microwave exposure. Above all, the role of cross-regulation of BDNF and NMDAR in the impairment of learning and memory induced by microwave exposure could be clarified.

微波辐射可致学习记忆能力下降，机制尚不明确。BDNF通过调节NMDAR磷酸化，增加其表达和活性，进而调节突触可塑性；NMDAR活化通过促进BDNF转录、表达和释放，促进神经递质的释放以及突触发育，但微波辐射后相关机制均未阐明。因此本项目拟以BDNF和NMDAR为靶分子，探讨BDNF和NMDAR 相互调控在不同条件微波辐射致学习记忆障碍中的作用。首先采用低剂量长期辐射和大剂量单次辐射两种条件，建立微波辐射学习记忆下降/突触传递障碍的动物和细胞模型，探讨不同条件微波辐射对BDNF和NMDAR的影响；其次给予BDNF或TrkB抑制剂，BDNF相关信号通路激酶抑制剂，研究BDNF及相关通路对NMDAR表达和磷酸化以及突触后信息传递的影响；并给予NMDAR激动剂或拮抗剂，探讨NMDAR对BDNF转录和翻译及突触前囊泡释放的影响；这可补充和完善微波辐射致学习记忆障碍的分子机制，并为其防治提供重要靶点。

研究背景：一定剂量微波辐射可引起学习记忆损伤，突触传递异常是微波辐射致学习记忆损伤的重要表现。BDNF和NMDAR是突触传递的信号分子，彼此相互调控，在LTP的产生和学习记忆的形成中发挥重要作用。因此，本研究以BDNF和NMDAR的相互调控为切入点，探讨微波辐射致海马神经元突触传递异常的机制，为微波辐射致学习记忆损伤的防护提供依据。.主要研究内容：（1）微波辐射致学习记忆障碍/突触传递障碍的动物/细胞模型的建立；（2）微波辐射对BDNF、NMDAR及其信号通路相关分子的影响；（3）BDNF及其信号通路对NMDAR的调控在微波辐射致突触传递障碍中的作用；（4）NMDAR对BDNF的调控在微波辐射致突触传递障碍中的作用。 .重要结果：（1）成功建立了不同条件微波辐射致突触传递异常的动物和细胞模型，筛选出了NMDAR、BDNF及其相关分子表达差异的辐射参数：20-30mW/cm2微波多次辐射可致海马神经元活性降低，树突棘密度增加，NMDAR和突触后相关蛋白、BDNF及其受体活化；50mW/cm2微波多次辐射可致海马神经元活性降低，树突棘密度降低，NMDAR和突触后相关蛋白、BDNF及其受体抑制。（2）阐明了不同平均功率密度微波多次辐射后BDNF与NMDAR的相互调控在突触后信息传递异常中的作用：30mW/cm2微波多次辐射后，NMDAR表达上调，促进BDNF的转录和表达，引起GABA释放障碍且激活PKC信号途径，进而上调NMDAR亚基及相关分子的表达，促进突触传递损伤的恢复。50mW/cm2微波多次辐射后，NMDAR表达下调，抑制BDNF的转录和表达，下调synaptobrevin致Glu释放减少，进而通过抑制PKC信号途径，下调NMDAR亚基以及相关分子的表达，导致突触传递异常。.科学意义：本研究揭示了30mW/cm2微波辐射后BDNF、NMDAR及其相关信号通路被激活，促进突触传递损伤的恢复；而50mW/cm2微波辐射后BDNF、NMDAR及其相关信号通路被抑制，导致突触传递的损伤；且BDNF与NMDAR相互影响彼此的转录和表达；提示BDNF的改变趋势可作为评价微波辐射致神经认知损伤程度的重要依据，但各种信号通路以及各类神经递质之间存在交互作用，因此不同条件微波辐射后什么因素引起BDNF、NMDAR及其相关信号通路的改变，仍需进一步深入研究。