趋化因子MCP-1对大鼠海马区NMDA受体介导的兴奋性突触后电流的影响

Effects of chemokine MCP-1 on NMDA-mediated exciatory postsynaptic current in hippocampal slice of rats

目的研究趋化因子MCP-1对大鼠海马CA1区NMDA受体介导的兴奋性突触后电流的影响。方法采用全细胞膜片钳技术,记录2.3 nmol·L^(-1)MCP-1对大鼠海马脑片CA1区NMDA受体尤其是其重要受体亚型NR2BR介导的兴奋性突触后电流的影响,观察MCP-1是否对海马CA1区神经元有易化兴奋性作用;应用微管相关蛋白-2(MAP-2)抗体染色的方法,观察海马CA1区神经元轴突结构的完整性,研究在NMDAR、AMPAR、CCR2受体拮抗剂分别存在的情况下,MCP-1引发海马脑片神经元结构损害的差异,观察上述各种拮抗剂是否对MCP-1导致的神经细胞结构损害有保护作用。结果灌流液内加入MCP-1能明显增加EPSCs、EPSCAMPAR、EPSCNMDAR电流幅度(P<0.05),MCP-1能增加EPSCNR2BR的电流幅度,冲洗掉MCP-1后上述电流可恢复到接近给药前基础值,说明MCP-1对EPSCNR2BR的易化和促进作用是可逆的。在海马脑片上所做的MAP-2免疫组化染色的实验结果显示MCP-1对神经元轴突结构有损害作用,该作用可被NMDA和AMPA受体拮抗剂或CCR2受体拮抗剂逆转。结论 MCP-1对大脑海马CA1区NMDA受体,尤其是NR2B受体介导的突触后神经元的兴奋性有明显易化作用,神经元过度兴奋引发兴奋性神经毒性而导致神经损伤。NMDA和AMPA受体拮抗剂或CCR2受体拮抗剂对MCP-1诱导的神经元轴突结构损伤起到明显保护作用,这些拮抗剂的神经保护效应可为寻找神经退行性疾病的潜在治疗方法提供非常有价值的线索。

Aim To explore how MCP-1 induces neu-rodisorder by determing the effects of MCP-1 on excita-tory postsynaptic current（EPSCs） in the CA1 region of rat hippocampal brain slices .Methods EPSCs, the AMPA receptor-mediated EPSC （EPSCAMPAR ）, NMDA receptor mediated EPSCs（EPSCNMDAR） and NR2BR re-ceptor-mediated EPSC （ EPSCNR2BR ） were recorded u-sing whole-cell patch recording techniques to observe the effects of 2.3 nmol· L-1 MCP-1 on pyramidal neu-rons in hippocampal CA1 region.Microtubule-associat-ed protein-2 （ MAP-2 ） staining was used to study whether MCP-1 induced dendritic injuries in hippocam-pal CA1 region and whether NMDAR , AMPAR or CCR2 receptor antagonists had protective effects a-gainst dendritic damage caused by MCP-1.Results ① Bath application of MCP-1 produced a significant enhancement of the amplitudes of EPSCs , EPSCAMPAR and EPSCNMDAR .②Further studies revealed that MCP-1 potentiated EPSC NR2BR; ③ The MCP-1-associated dendritic injuries were blocked by NMDAR , AMPAR and CCR2R antagonists respectively .Conclusions Our results suggest a potential role of MCP-1 which may play in neuroexcitotoxicity and neural injury via NMDA receptor（especially NMDAR subtype NR2BR） and CCR2 receptor .The antagonists of these receptors may have potential therapeutic effect for neurodegener-ation.