蝙蝠葛酚性碱对脑缺血大鼠海马CA3区诱发电位的影响

Effects of Phenolic Alkaloids of Menispermum dauricum on Evoked Potentials in Hippocampus CA3 Region in Ischemic Rats

目的探讨蝙蝠葛酚性碱(PAMd)对脑缺血大鼠海马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区诱发的群峰电位(PS);结扎大鼠双侧颈总动脉,造成急性不完全性脑缺血,观察PS幅度的变化;缺血前给予PAMd(5、10、20mg/kg),观察其对缺血后PS幅度的影响;并观察不同剂量谷氨酸(Glu)对诱发电位的影响。结果①急性不完全性脑缺血后,PS的幅度显著降低。②5、10、20mmol/LGlu注入后,PS的幅度均升高;当给予50mmol/LGlu时PS幅度则显著降低。③20mg/kgPAMd能部分改善脑缺血引起的PS幅度降低,并能减弱50mmol/LGlu降低PS幅度的作用。结论预先给予20mg/kgPAMd对高浓度Glu和急性脑缺血所致CA3区突触传递功能减弱有明显的改善作用。

Objective To observe the effects of phenolic alkaloids of Menispermum dauricum (PAMd) on synaptic transmission in hippocampus CA3 region in ischemic rats.Methods The evoked population spike (PS) was recorded in hippocampus CA3 region of normal rats in vivo. Transient incomplete global brain ischemia was caused by occluding both carotid arteries, and the change of PS amplitudes were observed. PAMd were injected intraperitoneally at 5, 10, 20 mg/kg respectively before ischemia and their effects on PS amplitudes were observed in ischemic rats. Different doses of glutamic acid(Glu) were injected locally in microdose and their effects on PS amplitudes were observed.Results After both carotid arteries had been occluded to cause incomplete global brain ischemia, the amplitudes of PS were decreased significantly. After the animals were subjected to a Glu intrahippocampal infusion of 5, 10, and 20 mmol/L, respectively, there was an increase of the amplitude of PS at all measured time points (5, 10, 20, 30, 40, 50, 60 min), but Glu 50 mmol/L significantly decreased the amplitudes of PS. Administration of PAMd (20 mg/kg) before ischemia could significantly increase the PS amplitudes after ischemia and PAMd significantly ameliorated the depressive effects of 50 mmol/L Glu on synaptic transmission in hippocampus CA3 region too.Conclusion Administration of PAMd (20 mg/kg) before ischemia significantly improved the weakened synaptic transmission in hippocampus CA3 region induced by brain ischemia, and significantly ameliorate the depressive effects of higher dose Glu.