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大鼠坐骨神经挤压损伤导致脊髓单突触反射回返性抑制的长时程减弱

舒良, 董幼镕, 严为宏, 翟宇, 王云, 李威^*

上海交通大学医学院附属第九人民医院，上海 200011；复旦大学脑科学研究院，医学神经生物学国家重点实验室，上海 200032

摘要

坐骨神经损伤是临床常见的周围神经疾病。神经损伤后再生肌肉和运动神经元会出现各种功能障碍，虽然其中一部分因素已被阐明，但多局限于受损神经局部，而对于再生后脊髓运动神经元的回返性抑制(recurrent inhibition, RI)通路的功能变化却很少被报道。本文研究大鼠短暂坐骨神经损伤后，恢复神经再支配(reinnervation)情况下，脊髓RI通路的功能变化。在正常或坐骨神经挤压(crush)受损后的成年大鼠上，通过刺激离断的脊髓背根(L5)，在外侧腓肠肌-比目鱼肌(lateral gastrocnemius-soleus, LG-S)神经或内侧腓肠肌(medial gastrocnemius, MG)神经记录单突触反射(monosynaptic reflex, MSR)，并同时在另一神经给予条件性刺激，以检测LG-S和MG运动神经元间RI的变化。结果显示：(1)脊髓运动神经元的RI在坐骨神经挤压受损后即基本丢失(<5周)，至损伤6周后部分恢复至正常的50%，并至少维持至损伤14周后；(2)一侧的坐骨神经损伤对对侧的RI没有影响；(3)外周神经损伤后，免疫组织化学方法显示脊髓运动神经元数目本身并不发生减少。以上结果表明，外周神经损伤即使在神经再支配后仍会引起脊髓运动神经元RI的长时程减弱，RI的减弱使运动神经元通过增强其功能来补偿损伤后外周肌肉力量上的减弱，提示外周神经损伤会导致中枢脊髓运动环路的可塑性变化。

关键词： 坐骨神经; 神经挤压; 脊髓; 回返性抑制

分类号：Q42

[Long term depression of the recurrent inhibition of monosynaptic spinal reflexes after sciatic nerve crush in adult rats.] [Article in Chinese]

SHU Liang, DONG You-Rong, YAN Wei-Hong, ZHAI Yu, WANG Yun, LI Wei^*

Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China； Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200032, China

Abstract

Sciatic nerve injury is a common disease of peripheral nerve in clinic. After nerve injury, there are many dysfunctions in motoneurons and muscles following regeneration. Previous studies mostly investigated the aspects related to the injured nerve, and the effect on the recurrent inhibition (RI) pathway of spine following regeneration was not fully understood. Following reinnervation after temporary sciatic nerve crush, the functional alteration of RI was studied. In adult rats, RI between lateral gastrocnemius-soleus (LG-S) and medial gastrocnemius (MG) motor pools was assessed by conditioning monosynaptic reflexes (MSRs) elicited from the cut dorsal roots and recorded from either the LG-S or MG nerves by antidromic stimulation of the synergist muscle nerve. The following results were obtained. (1) The RI of MSRs in rats was almost lost (<5 weeks) after sciatic nerve crush. Although the RI partially recovered following reinnervation (6 weeks), it remained permanently depressed (up to 14 weeks). (2) Sciatic nerve crush on one side did not affect the contralateral RI. (3) Sciatic nerve crush did not induce any motoneuron loss revealed by immunohistochemistry. Peripheral nerve temporary disconnection causes long term alterations in RI pathway which make up motoneuron’s function enhance for the alteration of muscle power and suggests that peripheral nerve injury induces long term plastic changes in the spinal motoneuron circuitry.

Key words: Sciatic nerve; nerve crush; spine; recurrent inhibition

收稿日期：2011-04-25　　录用日期：2011-05-03

通讯作者：李威　　E-mail: prof_wei_li@yahoo.com.cn

引用本文：

舒良, 董幼镕, 严为宏, 翟宇, 王云, 李威. 大鼠坐骨神经挤压损伤导致脊髓单突触反射回返性抑制的长时程减弱[J]. 生理学报 2011; 63 (4): 291-299.

SHU Liang, DONG You-Rong, YAN Wei-Hong, ZHAI Yu, WANG Yun, LI Wei. [Long term depression of the recurrent inhibition of monosynaptic spinal reflexes after sciatic nerve crush in adult rats.] [Article in Chinese]. Acta Physiol Sin 2011; 63 (4): 291-299 (in Chinese with English abstract).