摘要
目的:应用清醒大鼠脑微透析技术,观察N-甲基-D-天冬氨酸受体激动剂和阻断剂对大鼠海马兴奋性氨基酸释放的影响,探讨N-甲基-D-天冬氨酸受体对大鼠海马兴奋性氨基酸释放的自身调节作用。方法:实验于2003-12在锦州医学院药理教研室完成。45只雄性SD大鼠,横跨海马背部植入一自制的透析探头,待大鼠清醒后24h用人造脑脊液,N-甲基-D-天冬氨酸250,500μmol/L,N-甲基-D-天冬氨酸500μmol/L+MK-801100μmol/L,MK-801100μmol/L,甘氨酸500μmol/L,7-氯犬尿烯酸200μmol/L灌流,灌流速度为5μL/min,每20min收集一次透析液,采用邻苯二甲醛-β-巯基乙醇衍生化反相梯度洗脱荧光检测透析液中谷氨酸和天冬氨酸的水平。结果:45只大鼠均进入结果分析。海马内局部灌流N-甲基-D-天冬氨酸250,500μmol/L可明显增加细胞外基础状态下谷氨酸和天冬氨酸的水平。非竞争性N-甲基-D-天冬氨酸受体拮抗剂MK-801(100μmol/L)可拮抗N-甲基-D-天冬氨酸(500μmol/L)引起的谷氨酸释放增加作用。单独应用MK-801(100μmol/L)对基础状态下谷氨酸的水平没有影响。局部灌流N-甲基-D-天冬氨酸受体协同激动剂甘氨酸500μmol/L也可明显增加细胞外基础状态下谷氨酸的水平。局部灌流N-甲基-D-天冬氨酸上甘氨酸部位的选择性阻断剂7-氯犬尿烯酸200μmol/L可以拮抗甘氨酸引起的谷氨酸释放增加作用。结论:兴奋性氨基酸受体N-甲基-D-天冬氨酸受体的激活增加海马内兴奋性神经递质的释放,这种N-甲基-D-天冬氨酸受体可能存在于突触前膜(兴奋性神经末梢膜上),即自身调节受体正反馈调节兴奋性氨基酸的释放。
AIM： To investigate the autoregulative effect of N-methyl-D-aspartate （NMDA） receptor on the release of excitatory amino acids from the rat hippocampus, by observing the effect of N-methyl-D-aspartate （NMDA） receptor agonists and antagonists on the release of excitatory amino acids from the rat hippocampus using microdialysis technique in wakened rat brain. METHODS： The experiment was conducted in the Department of Pharmacology, Jinzhou Medical College in December 2003. Forty-five male Sprague-Drawly （SD） rats were anesthetized. A microdialysis probe was transversely implanted in the dorsal hippocampus. At 24 hours after recovery, the rats were perfused with artificial cerebral spinal fluid, NMDA 250 μmol/L and 500 μmol/L, NMDA at 500 μmol/L plus MK-801 100 μmol/L, MK-801 100 μmol/L, glycine 500 μmol/L, 7-Cl-kynurenic acid （7-CI-KA） 200 μmol/L at 5 mL per minute, and the dialysate was collected every 20 minutes. The levels of glusate and aspartate in the dialysate were determined by using a HPLC connected with a fluorometric detector. RESULTS： All the 45 rats were analyzed in the result. Local infusion of NMDA 250, 500 mmol/L in hippocampus resulted in a striking increase in extracellular levels of glusate and aspartate in basal levels. The NMDA- induced increase in extracellular concentration of glusate and aspartate was significantly reduced by prior perfusion with dizocolpine （Mk-801） 100 μmol/L, a non-competitive NMDA receptor antagonist. However, MK-801 100 μmol/L had no apparent influence on the basal level of glusate and aspartate. Local infusion with glycine 500 μmol/L, a coordinate agonist at the glycine site associated to the NMDA receptor, significantly increased basal level of glusate. Such glycine-induced effects were significantly reduced by 7-CI-KA, a selective blocker of the glycine site located in the NMDA receptor. CONCLUSION： It is proposed that activation of NMDA receptors by endogenous glusate increases the subsequent release of excitatory in the hippocam
出处
《中国临床康复》
CSCD
北大核心
2005年第28期141-143,共3页
Chinese Journal of Clinical Rehabilitation
基金
辽宁省教育委员会基金资助课题(202173362)~~
