Effects of general anesthetics in hippocampus of SAM mice and establishment of the safety for Anesthesia in senile dementia

为了探讨痴呆是否改变了中枢神经系统的麻醉作用，我们利用痴呆模型小鼠研究了全麻药对海马区突触传递的影响。采用顺向刺激Schaffer侧支连合纤维(测试脉冲)的方法，在体外诱发大鼠海马CA1区锥体神经元的群峰电位。将第二个刺激电极置于海马区(预脉冲)可增强对CA1的反复抑制。预脉冲作为序列刺激，激活抑制性中间神经元突触前终末的γ-氨基丁酸的释放和消耗。七氟醚和硫喷妥钠对痴呆模型小鼠突触传递的抑制作用比对照小鼠更大。脉冲前训练方案显示，麻醉剂诱导的GABA放电在痴呆症小鼠比对照小鼠更强。痴呆增强了全身麻醉药的作用，这是由于突触前终末释放的GABA增加。

In order to investigate whether dementia modifies the anesthetic actions in the central nervous systems, we have studied effects of general anesthetics on the hippocampal synaptic transmission using the dementia model mice. Field population spikes of hippocampal CA1 pyramidal neurons were elicited in vitro using orthodromic stimulation of Schaffer collateral commissural fibers(test pulse). The recurrent inhibition was enhanced with the second stimulating electrode placed in alveus hippocampi(prepulse) to activate recurrent inhibition of CA1. The prepulses were applied as train stimuli to activate release and then depleteγ-amino-butyric acid(GABA) at presynaptic terminals of inhibitory interneurons. Sevoflurane and thiopental had greater actions on inhibitory synaptic transmission in dementia model mice than in control mice. The pre-pulse train protocol revealed that the anesthetic-induced GABA discharge was more enhanced in dementia mice than in control mice. Dementia enhances the actions of general anesthetics due to the increase in GABA release from presynaptic terminals.