中国临床康复2005，Vol.9Issue(36)：136-139,4.
电磁脉冲对大鼠脑海马N-甲基-D-天冬氨酸受体活性的影响
Effects of electromagnetic pulse on N-methyl-D-aspartate receptor activity in rat hippocampus
摘要
Abstract
BACKGROUND: Electromagnetic pulse (EMP) is high-energy non-ionizing radiation covering a wide spectrum with strong capability of destruction of electronic devices and inducing injuries in biological organisms. In previous studies we found EMP could cause obvious reduction in the learning and memory ability of rats and affect the formation of long-term potentiation of rat hippocampus.OBJECTIVE: To observe the effect of EMP on the content of amino acid neurotransmitters and N-methyl-D-aspartate (NMDA) receptor activity in rat hippocampus.DESIGN: Randomized controlled experiment and analysis of variance.SETTING: Institute of Radiation Medicine, Academy of Military Medical SciencesMATERIALS: The experiment was conducted in the Institute of Radiation Medicine, Academy of Military Medical Sciences from January to March 2004. Totally 32 male Wistar rats were used and randomized into EMP group (n=26) and control group (n=6).METHODS: Rats in the EMP group were decapitated and the hippocampi were removed immediately 3, 6, 24 and 48 hours after EMP radiation (6×104 V/m, with pulse rise time of 20 ns, pulse width of 30 μs, frequency of 2.5 pulses/minute for 2 minutes). Glutamate contents were detected with high-performance liquid chromatograpy (HPLC). Radioactive ligand-receptor binding test was performed with glutamate as the ligand with 3H labeling. The rats in the control group were not given any treatment before put to death under anesthesia.MAIN OUTCOME MEASURES: ① Changes in excitatory and inhibitory amino acid contents in the hippocampus of the rats. ② Rat hippocampal Bmax of NMDA receptor and changes in equilibrium dissociation constant (Kd).RESULTS: All the 32 rats entered the result analysis. NMDA content was significantly increased in the EMP group with a peak level of (17.25±1.63)μmol/L immediately, 3 and 6 hours after EMP radiation in comparison with that in the control group [(10.56±1.5)μmol/L, P ＜ 0.05]. Glutamate content was also increased at the 3 time points with the peak level of (13.67±0.95) μmol/L, which was significantly higher than that in the control group [(6.94±1.1) μmol/L, P ＜ 0.05]. NMDA and glutamate contents was both decreased 24 hours after EMP exposure and resumed the normal level after 48 hours. The contents of glycine, taurine and gamma-aminobutyric acid also rose after EMP exposure and recovered 48 hours after the radiation. The ratio of glycine/gamma-aminobutyric increased markedly immediately after EMP exposure (P ＜ 0.05), but decreased obviously 24hours after the exposure and was restored to the level of the control group.The Kd of NMDA receptor began to decrease immediately after EMP exposure, which was the most obvious at 3 hours (P ＜ 0.05), followed then by gradual increase at 6 hours and reaching the normal level at 48 hours. The Bmax of NMDA receptor in rat hippocampus was decreased significantly 3and 6 hours after irradiation (P ＜ 0.05), and increased gradually since 24hours to a level significantly higher than the normal at 48 hours (P ＜ 0.05).CONCLUSION: EMP exposure induces increases in excitatory amino acid contents and the Glu/γ-aminobutyric acid (GABA) ratio in rat hippocampus, increases the affinity and decrease the density of NMDA receptors, suggesting that excessive release of excitatory amino acids and changes in NMDA receptor activity may contribute to cognitive impairment in rats.关键词
海马/电磁学/兴奋性氨基酸类/色谱法,高压液相/受体,N-甲基-D-天冬氨酸/放射配体测定分类
医药卫生引用本文复制引用
李玉红,李锦,苏瑞斌,吴宁,李子建,王水明,彭瑞云,王德文..电磁脉冲对大鼠脑海马N-甲基-D-天冬氨酸受体活性的影响[J].中国临床康复,2005,9(36):136-139,4.基金项目
全军医药卫生指令性课题(01L023) Supported by: Military Program of Medicine and Hygiene, No. 01L023 （01L023）
