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脊髓运动神经元突触传递长时程增强的受体动力学分析

罗浩, 秦雯, 张艳, 王邦安, 汪萌芽^*

皖南医学院细胞电生理研究室，芜湖 241002

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。

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

[Receptor kinetics analyses of long-term potentiation of synaptic transmission in spinal cord motoneurons in vitro.] [Article in Chinese]

LUO Hao, QIN Wen, ZHANG Yan, WANG Bang-An, WANG Meng-Ya^*

Cell Electrophysiology Laboratory, Wannan Medical College, Wuhu 241002, China

Abstract

The aim of the present study is to observe the receptor kinetics property of long-term potentiation (LTP) of excitatory postsynaptic 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 funiculus (iVLF) 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 (K_T) 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 K_T 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 of postsynaptic receptors in the early stage of iVLF-LTP in some MNs.

Key words: Spinal cord; motoneurons; descending activation; long-term potentiation; receptor kinetics

收稿日期：2013-08-19　　录用日期：2013-12-13

通讯作者：汪萌芽　　E-mail: wangmy@wnmc.edu.cn

引用本文：

罗浩, 秦雯, 张艳, 王邦安, 汪萌芽. 脊髓运动神经元突触传递长时程增强的受体动力学分析[J]. 生理学报 2014; 66 (2): 129-134.

LUO Hao, QIN Wen, ZHANG Yan, WANG Bang-An, WANG Meng-Ya. [Receptor kinetics analyses of long-term potentiation of synaptic transmission in spinal cord motoneurons in vitro.] [Article in Chinese]. Acta Physiol Sin 2014; 66 (2): 129-134 (in Chinese with English abstract).