脊髓运动神经元突触传递长时程增强的受体动力学分析  

Receptor kinetics analyses of long-term potentiation of synaptic transmission in spinal cord motoneurons in vitro

作　　者：罗浩[1] 秦雯[1] 张艳[1] 王邦安 汪萌芽[1] 

机构地区：[1]皖南医学院细胞电生理研究室,芜湖241002

出　　处：《生理学报》2014年第2期129-134,共6页Acta Physiologica Sinica

基　　金：supported by the National Natural Science Foundation of China(No.31271155)

摘　　要：本文旨在观察下行通路激活在脊髓运动神经元(motoneuron,MN)诱发兴奋性突触后电位(excitatory postsynaptic potential,EPSP)的长时程增强现象(long-term potentiation,LTP)之受体动力学性质。应用8～14日龄新生大鼠离体脊髓MN细胞内记录技术,观察同侧腹外侧索(ipsilateral ventrolateral funiculus,iVLF)电刺激诱发的iVLF-EPSP的变化,进行EPSP受体动力学分析。结果显示,EPSP的幅度、曲线下面积和最大上升斜率与刺激强度呈正相关(P<0.05或P<0.01);而EPSP表观受体动力学分析的参数中表观解离速率常数K2和表观平衡解离常数KT与刺激强度呈负相关(P<0.01或P<0.05)。给予iVLF强直刺激(100 Hz,50脉冲/串,波宽0.4～1.0 ms,共6串,串间隔10 s,10～100 V),在11个记录的MNs中有5个MNs的EPSP幅度增大到基础值的120%以上,且至少维持30 min,可以被判为iVLF-LTP,同时EPSP的曲线下面积和最大上升斜率也增大到基础值的120%以上。选择iVLF-LTP过程中的EPSP进行表观受体动力学分析,结果显示有3个MNs的K2和KT在强直刺激后10 min内减小到基础值的80%以下,后逐渐有所恢复。以上受体动力学分析结果提示,部分MNs的iVLF-LTP早期可能涉及突触后受体亲和力增强的机制。The aim of the present study is to observe the receptor kinetics property of long-term potentiation （LTP） of excitatory post- synaptic potential （EPSP） in spinal cord motoneurons （MNs） by descending activation. The intracellular recording techniques were conducted in spinal cord MNs of neonatal rats aged 8-14 days. The changes of EPSP induced by ipsilateral ventrolateral fimiculus 0VLF） stimulation （iVLF-EPSPs） were observed, and receptor kinetics of iVLF-EPSPs were analyzed. The results showed that, the amplitude, area under curve and maximum left slope of EPSP were positively correlated with stimulus intensity （P 〈 0.05 or P 〈 0.01）, while the apparent receptor kinetic parameters apparent dissociation rate constant （K2）, apparent equilibrium dissociation constant （KT） of EPSP were negatively correlated with stimulus intensity （P 〈 0.01 or P 〈 0.05）. The iVLF-EPSPs were persistently increased after tetanic stimulation （100 Hz, 50 pulses/train, duration 0.4-1.0 ms, 6 trains, main interval 10 s, 10-100 V） in 5 of 11 tested MNs. The amplitude of iVLF-EPSPs was potentiated to more than 120% of baseline and lasted at least 30 min, which could be referred to as iVLF-LTP. Meanwhile, the area under curve and maximum left slope of EPSPs were also increased to more than 120% of baseline. During iVLF-LTP, apparent receptor kinetics analyses of iVLF-EPSPs indicated that K2 and Kr were decreased significantly to less than 80% of the baseline within 10 min and gradually and partially recovered in 3 MNs. These results of receptor kinetics analyses of iVLF-EPSPs suggest a possible enhancement in affinity ofpostsynaptic receptors in the early stage of iVLF-LTP in some MNs.

关 键 词：脊髓 运动神经元 下行激活 长时程增强 受体动力学 

分 类 号：R338.1[医药卫生—人体生理学]