四次甲基二砜四胺中毒所致顽固性癫痫对大鼠大脑皮质NMDA受体亚单位表达的影响

Effects of tetramine induced-refractory epilepsy on the expression of NMDAR subunits in rat cortex

目的观察剧毒杀鼠剂四次甲基二砜四胺(tetramine,TET)所致顽固性癫痫(refractory epilepsy,RE)大鼠大脑皮质NMDA受体亚单位在染毒后不同时间的表达变化,研究NMDA受体亚单位表达与TET诱发癫痫及由此引发脑损伤的相关性。方法建立TET(0.4 mg/kg,ig)所致大鼠RE及脑损伤模型,采用实时荧光定量PCR及Western印迹技术,测定RE动物大脑皮质NMDA受体不同亚型在染毒后不同时间mRNA及蛋白水平的表达变化。结果大鼠TET染毒10～25 min后即出现RE,染毒后24 h,其大脑皮质出现明显病理学改变。NR2A的mRNA及蛋白表达水平在皮质出现病理学改变前即显著降低(P<0.01),至染毒后72 h,尚未恢复正常水平(P<0.01);NR2B蛋白水平的表达在病理学改变出现前未见显著性改变,至染毒后72 h,表达显著降低(P<0.01);但其mRNA水平在整个观测时间点未见显著性改变。结论 TET所致RE可诱发NMDA亚单位NR2A及NR2B表达下调,NR2A表达下调可能与RE发生及由此引发脑损伤的关系更为直接。

ObjectiveTo examine the expression of N-methyl-D-aspartate（NMDA） receptor subunits at different time points during refractory epilepsy（RE） development induced by high-toxic rodenticide tetramine（TET） and to investigate the relation between the RE development,the corresponding brain damage and the expression of NMDA receptor subunits.MethodsAfter the establishment of the TET（0.4 mg/kg,ig） induced RE and neuropathology model,the levels of mRNA and protein of NR2A and NR2B in rat cortex at different time points since RE onset were tested by real-time quantitative polymerase chain reaction（RT-PCR） and Western blotting.ResultsThe RE and neuropathological changes in rat cortex were shown at 10-25 min and 24 h,respectively,since TET poisoning.The level of mRNA and protein of NR2A decreased significantly before neuropathological changes and kept down-regulating until 72 h while the level of mRNA and protein of NR2B remained unchanged before 24 h.However,by 72 h,the level of protein decreased obviously but the level of mRNA remained unchanged throughout RE development.ConclusionThe down regulation of NR2A and NR2B is found in the course of TET induced RE and neuropathology.The changes in NR2A might be closely related to the RE development and the brain damage induced by TET.