新型tacrine双联体对培养大鼠海马神经元NMDA受体作用位点的研究

Effect of Bis(7)-tacrine to NMDA Receptor Modulatory Site in Cultured Rat Hippocampal Neurons

目的:研究新型tacrine双联体bis(7)-tacrine对NMDA受体的作用位点.方法:大鼠海马神经元原代培养,全细胞膜片钳记录培养大鼠海马神经元上NMDA激活电流变化.结果:细胞外液pH值从8.1改变到6.7,在细胞外液中加入二硫苏糖醇(2 mmol/L)、精胺(10 mol/L)、镁离子(50～500 mol/L)或锌离子(5～20 mol/L)均不引起bis(7)-tacrine对NMDA电流抑制率的改变.电极内液中加入5 mol/L bis(7)-tacrine也未观察到外加的0.5 mol/L bis(7)-tacrine对30 mol/L NMDA激活电流抑制率的改变.0.5 mol/L bis(7)-tacrine及1 mol/L dizocilpine(MK-801)分别对30 mol/L NMDA激活电流抑制了36%和22%,而在两种药物都存在的条件下,30 mol/L NMDA电流仅被抑制了37%.结论:bis(7)-tacrine虽然不大可能作用于MK-801位点,但MK-801和bis(7)-tacrine之间可能存在着相互的负性调节作用.

Objective：To study the modulatory site of bis（7）-tacrine on NMDA receptors.Methods：The effect of bis（7）-tacrine on NMDA-activated currents was investigated using whole-cell patch-clamp recording in cultured rat hippocampal neurons in the absence and presence of different NMDA receptor modulaters.Results：The inhibitory rates NMDA-activated currents by bis（7）-tacrine were neither altered by changing extracellular pH（pH 8.1～6.7）,nor by adding dithiothreitol（2 mmol/L）,spermine（10 mol/L）,Mg2＋（50～500 mol/L）,or Zn2＋（5～20 mol/L） to the external solution.5 mol/L bis-tacrine in the recording pipette solution did not alter the inhibition rate of 30 mol/L NMDA-activated current by 0.5 mol/L bis（7）-tacrine applied externally.0.5 mol/L bis（7）-tacrine and 1 mol/L dizocilpine（MK-801） inhibited NMDA-activated currents by 36 % and 22 %,respectively;co-application of these two drugs only inhibited NMDA-activated current by 37 %.Conclusion：Although bis（7）-tacrine is very unlikely acting at the MK-801 site,MK-801 and bis（7）-tacrine may negatively modulate the inhibition of NMDA receptor function with each other.