膜电位的不同波动对小鼠大脑皮质GABA能神经元内在特性的影响

Effect of different fluctuations of membrane potential on the intrinsic characteristics of GABA neurons in mouse cerebral cortex

目的:探讨膜电位的不同波动对小鼠大脑皮质γ-氨基丁酸(GABA)能神经元内在特性影响及对神经编码的调控。方法:取出生15~20 d FVB-Tg(Gad GFP)45704 Swn/J小鼠进行麻醉,断头取脑制作切片,将脑片置于充分氧合的人工脑脊液中继续孵育2 h。采用全细胞记录方法进一步探讨快速后超极化(fAHP)、慢速后超极化(sAHP)、动作电位不同复极和快速后去极化(fADP)对神经元内在特性的影响及对神经编码的调控。结果:fAHP和sAHP相比,fAHP影响下的动作电位的绝对不应期(ARP 2)较短(P<0.01),阈值(Vts-Vr 3)较高(P<0.01);与fAHP相比,动作电位未完全复极时,ARP 2较短,当为阈强度0.25倍时,ARP 2最短(P<0.05);与fAHP比较,fADP程度越低,ARP 2越短,当在静息电位水平时,ARP 2最短(P<0.05)。结论:大脑皮层GABA能神经元在整合突触输入后,当膜电位波动时其内在特性发生可塑性变化,不同输入模式通过影响大脑皮层GABA能神经元动作电位的内在特性,从而调控GABA能神经元对输入信号的编程能力。

Objective:To explore the effects of different fluctuations of membrane potential on the intrinsic characteristics and regulation of neural coding of GABA-ergic neurons in mouse cerebral cortex.Methods:The brain slices were prepared from FVB-Tg(Gad GFP)4570Swn/J mice(postnatal day 15-20),and incubated in artificial cerebrospinal fluid with sufficient oxygenation for 2 h.The effects of fast post-polarization(fAHP),slow post-hyperpolarization(sAHP),different repolarization of action potential and fast post-polarization(fADP)on the intrinsic characteristics of neurons and regulation of neural coding were further studied by whole-cell recording.Results:Compared with sAHP,the absolute refractory period(ARP 2)and threshold(vts-Vr 3)of the action potential under the influence of fAHP were shorter and higher,respectively(P<0.01).Compared with fAHP,the ARP 2 was shorter when the action potential was not fully repolarized,and the ARP 2 was the shortest when the threshold intensity was 0.25 times(P<0.05).Compared with fAHP,the lower the fADP level was,the shorter the ARP 2 was,and the ARP 2 was the shortest at the resting potential level(P<0.05).Conclusions:After the integrating synaptic input,the plasticity of intrinsic characteristics of cerebral cortex GABA-ergic neurons changes when the membrane potential fluctuates.Different input modes affect the intrinsic characteristics of action potential of cerebral cortex GABA-ergic neurons,thereby regulating the programming ability of GABA-ergic neurons to input signals.