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目的 探讨γ-aminobutyric acid(GABA)及其受体拮抗剂对正常及脑缺血大鼠海马CA3区神经元突触传递功能的影响。方法在体记录正常大鼠海马CA3区诱发的群峰电(population spike,PS);结扎大鼠双侧颈总动脉,造成急性不完全性全脑缺血,观察PS幅度变化;采用局部微量给药,观察药物对PS幅度的影响。结果①GABA 100,200 mmol·L-1局部注入后,PS的幅度显著降低.bicuculline 1 mmol·L-1能明显拮抗GABA200 mmol·L-1对PS幅度降低的作用。②Glu 10 mmol·L-1注入后,PS的幅度较注药前显著增加。而Glu 50 mmol·L-1注入后,PS的幅度则较注药前显著降低。③GABA 200 mmol·L-1能显著降低Glu10 mmol·L-1所导致的PS幅度增加,并能减弱Glu 50 mmol·L-1对PS幅度的降低作用。④急性不完全性全脑缺血(结扎双侧颈总动脉)后,PS的幅度显著降低。GABA 200 mmol·L-1能减轻脑缺血所致的PS幅度的降低。结论 GABA对正常大鼠海马神经元突触传递的兴奋性具有一定抑制作用。并能明显改善较大剂量谷氨酸和急性脑缺血对海马CA3区神经元突触传递的影响。
Objective To investigate the effect of γ-aminobutyric acid (GABA) and its receptor antagonist on synaptic transmission in hippocampal CA3 neurons in normal and ischemic rats. Methods The population spike (PS) induced by hippocampal CA3 region of normal rats was recorded in vivo. The bilateral common carotid arteries were ligated and the acute incomplete global cerebral ischemia was induced. The changes of PS amplitude were observed. Medicine, observe the impact of drugs on PS amplitude. Results ① The amplitude of PS decreased significantly after 100,200 mmol·L-1 GABA injection.bicuculline 1 mmol·L-1 could significantly antagonize the effect of GABA200 mmol·L-1 on PS amplitude decrease. ②Glu 10 mmol·L-1 injection, the amplitude of PS than before injection significantly increased. After Glu 50 mmol·L-1 injection, the amplitude of PS decreased significantly compared with that before injection. ③ GABA 200 mmol·L-1 could significantly reduce the increase of PS amplitude induced by Glu10 mmol·L-1 and decrease the amplitude of PS decreased by Glu 50 mmol·L-1. ④ Acute incomplete global cerebral ischemia (bilateral carotid artery ligation), PS amplitude was significantly reduced. GABA 200 mmol·L-1 can reduce the decrease of PS amplitude induced by cerebral ischemia. Conclusion GABA can inhibit the excitability of synaptic transmission in normal rat hippocampal neurons. And can significantly improve the effect of higher doses of glutamate and acute cerebral ischemia on synaptic transmission in neurons of hippocampal CA3 region.