丙泊酚和依托咪酯对小鼠海马锥体神经元电生理特性影响的比较

Comparing effects of propofol and etomidate on electrophysiology properties of hippocampal pyramidal neurons of mice

目的:比较全身静脉麻醉药丙泊酚和依托咪酯对小鼠海马锥体神经元膜特性和微小突触后电流反应(m EPSCs)的影响。方法:运用全细胞膜片钳技术对C57小鼠海马细胞记录并比较分别在丙泊酚和依托咪酯作用前后动作电位反应和m EPSCs。结果:丙泊酚和依托咪酯均使神经元动作电位发放个数由8个降低至2个左右,使第一发放延时均显著延长,并使第一动作电位和第二动作电位峰值间隔显著增加,而动作电位峰值均无差异,另外丙泊酚组峰值间隔比依托咪酯组小。记录m EPSCs并分析发现丙泊酚组可降低m EPSCs发放频率,而对电流幅度和半峰宽无影响。依托咪酯组使m EPSCs发放频率降低,且使突触后电流幅度降低,半峰宽增加。结论:丙泊酚和依托咪酯均可抑制海马锥体细胞动作电位发放,且对动作电位发放延时和反应灵敏性均有抑制作用。丙泊酚通过抑制突触前囊泡释放来降低突触兴奋性传递,而对突触后无影响。依托咪酯同时抑制突触前囊泡释放和突触后通道灵敏性,从而抑制神经元m EPSCs反应。

Objective To compare the effects of systemic intravenous anesthetics, propofol, and etomidate on membrane characteristics and miniature excitatory postsynaptic currents （mEPSCs） of hippocarnpal pyramidal neurons of mice. Methods The whole cell patch clamp technique was applied to record the hippocampal pyramidal neurons of C57 mouse. And the responses of action potential and mEPSCs before and after the application of propofol and etomidate were compared. Results Propofol and etomidate significantly decreased the number of action potential from 8 to 2, obviously increased the first spike latency and interspike interval between the first action potential and the second action potential. No significant differences were found in the peak value of action potential, and the interspike interval in propofol group was smaller than that in etomidate group. The mEPSCs were recorded. And the analyzed results showed that propofol decreased the discharge frequency of mEPSCs, but had no influence on current amplitude and half peak width, and that etomidate reduced the discharge frequency of mEPSCs, decreased the postsynaptic current amplitude and increased the half peak width. Conclusion Both propofol and etomidate inhibit the hippocampal pyramidal cell action potential spike and the spike latency of action potential and response sensitivity. Propofol reduces the excitatory synaptic transmission by inhibiting presynaptic vesicle release, without affecting postsynaptic, while etomidate inhibits mEPSCs of neuron by inhibiting the presynaptic vesicle release and postsynaptic channel sensitivity.