离体脊髓运动神经元突触反应的表观受体动力学分析

Analysis of the apparent receptor kinetics from synaptic responses in spinal cord motoneurons in vitro

目的:探讨离体脊髓运动神经元(MN)对下行激活的突触反应的表观受体动力学分析方法。方法:应用新生大鼠(8～14 d)脊髓切片MN细胞内记录技术,在腹外侧索(iVLF)电刺激在MN诱发的兴奋性突触后电位(iVLF-EP-SP)中,选择动力学过程不同的3种类型iVLF-EPSPs,应用受体的动力学分析中结合动力学曲线和解离动力学曲线的直线化公式,分别对iVLF-EPSP的上升相和下降相进行直线化和回归分析,求出表观结合速率常数K1、表观解离速率常数K2、表观平衡解离常数KT和表观最大反应Vmax值。结果:在15个记录到iVLF-EPSPs的MNs中,对6个MNs的iVLF-EPSPs参数分析表明幅度和曲线下面积与电刺激强度呈正相关(P<0.01和P<0.05)。选阈强度(T)电刺激诱发的上升相和下降相动力学不同的3种类型iVLF-EPSPs进行分析,其结合动力学曲线的直线化回归的相关系数(r)为0.9397～0.9621(均P<0.01),而解离动力学曲线的相应值为-0.8836～-0.9690(均P<0.01),并求得K1,K2,KT和Vmax值分别为0.364～2.330 T-1.ms-1,0.055～0.189ms-1,0.025～0.284 T,1.968～4.367 mV。结论:突触反应的递质与受体作用动力学过程可以用表观受体动力学方法进行分析,可能是突触可塑性等研究中进行受体动力学监测的一个简单可行方法。

Objective ：To explore an analysis method for apparent recep- tor kinetics from synaptie response in motoneurons （MNs） in spinal cord slices in vitro. Methods：The intracellular recordings were performed in MNs of spinal cord slices isolated from neonatal rats （8 - 14 days old）, and excitatory postsynaptie potentials （EPSPs） were evoked by ipsilateral ventrolateral funiculus （ iVLF ） electrical stimulation （ iVLF-EPSP ）. Three types of iVLF-EPSPs with different kinetic process evoked by threshold stimulus intensity （T） were selected for analysis of the apparent receptor kinetics. The linearized formulas of receptor kinetics of association and dissociation kinetic curves were applied to estimate the apparent association rate constant（ K1 ）, dissociation rate constant （K2 ）, equilibri- um dissociation constant （ KT ） and maximum response （ Vmax ） by linear regression analysis of the rising phase and declining phase of iVLF-EP- SPs. Results ： Among 15 MNs with iVLF-EPSPs, parametric analysis of iV~ LF-EPSPs in 6 MNs indicated that amplitude and area under curve were both positively correlated with the intensity of stimulation （ P 〈 0.01 and P 〈 0.05 ）. Linear regression analyses of separate 3 types of iVLF-EPSPs in rising phase and declining phase evoked by threshold stimulation led to values of correlation coefficient （r） of 0.9397 -0.9621 （all P 〈 0.01） and - 0. 8836 - - 0. 9690 （ all P 〈 0.01 ） for linearization of association and dissociation kinetic curves, and the values of （0. 364 - 2. 330 ） T - 1 · ms-1,（0.055-0.189） ms-1,（0.025-0.284） Tand （1.968- 4. 367） mV for K1 , K2 , KT and Vmax, respectively. Conclusion ： Apparent receptor kinetics analysis may be applied to examination Of the transmitter-receptor binding kinetics in synaptic response and tends to be a simple and feasible approach to estimate the receptor kinetics property in synaptie plasticity research.