离体脊髓运动神经元介导下行激活和外周传入的受体机制  

Receptor mechanisms underlying synaptic responses of motoneurons to the descending activation and afferent input in neonatal rat spinal cord in vitro

作　　者：汪丽娜[1] 汪萌芽[1] 

机构地区：[1]皖南医学院细胞电生理研究室,安徽芜湖241001

出　　处：《皖南医学院学报》2007年第1期3-6,10,共5页Journal of Wannan Medical College

基　　金：国家自然科学研究基金(30270366);安徽省人事厅人才专项基金(2003);安徽省自然科学基金(050430401)

摘　　要：目的：比较离体脊髓运动神经元（MN）介导下行激活和外周传入突触传递的受体机制。方法：应用新生大鼠（8～14d）脊髓切片MN细胞内记录技术，记录电刺激腹外侧索（VLF）和背根（DR）诱发的兴奋性突触后电位（EPSP）。结果：同侧VLF和DR刺激可对应诱发VLF-EPSP和DR-EPSP，与DR—EPSP相比，VLF—EPSP呈现潜伏期短、幅度高和上升快的特点，而且这一特征在用毕扣扣灵（30〉mol／L）或印防己毒素（30μmol／L）和士的宁（1．0μmol／L）消除抑制性突触后电位的影响后（即纯的EPSP成分）持续存在。非NMDA受体阻断剂DNQX（1．0μmol／L）对纯的DR—EPSP和VLF-EPSP均有抑制作用，对两者快成分的抑制都较明显，而NMDA受体阻断剂AP5（30μmol／L）在抑制VLF—EP—SP和DR—EPSP时，对DR—EPSP的慢成分抑制更为显著。在5个MNs上可同时记录到同侧电刺激诱发的VLF—EP—SP、DR—EPsP及外源性谷氨酸反应。结论：在脊髓介导VLF的下行激活和外周传人的EPSP可能都是谷氨酸类递质，下行激活可能以非NMDA受体为主，而非-NMDA和NMDA受体在外周传入中均起重要作用，显示了明显的差异性。Objective：To compare the receptor mechanisms underlying synaptic responses of motoneurons （MNs） to the descending activation and afferent input in neonatal rat spinal cord in vitro. Methods ： The intracellular recordings were performed from MNs in neonate rat （8- 14 days old） spinal cord slices and cell electrophysiological parameters of excitatory postsynaptic potential（EPSP） evoked by ventrolateral funiculus （VLF） and dorsal root （DR） stimulation were observed from the recorded MNs. Results ： （1）EPSP evoked ipsilaterally by VLF and DR stimulation were observed from the same MNs （ n = 35）. Compared with DR-EPSP, VLF-EPSP showed the characteristics of shorter latency, higher amplitude and faster rise, which persisted in the presence of bicuculline （30 μmol/L） or picrotoxin （30 μmol/L） and strychnine （ 1.0 μmol/L） （ n = 9）. （2）VLF-EPSP（ n = 5） and DR-EPSP（ n = 5） were both sensitive to DNQX （ 1.0 μmol/L） and inhibited significantly （ P 〈 0.05） when pretreated by bicuculline or picrotoxin and strychnine. （3） AP5 （30 μmol/L） could inhibit both VLF-EPSP （ n = 3） and DR-EPSP （ n = 3） in the presence of bicuculline or picrotoxin and strychnine while the amplitude of DR-EPSP were highly suppressed. Conclusion ： The possible neurotransmitters mediating VLF- and DR-EPSP are excitatory amino acids. Non-NMDA receptors are critically involved in the synaptie transmissions of descending activation and both non-NMDA and NMDA are involved in afferent inputs.

关 键 词：运动神经元 突触传递 下行激活 外周传入 DNQX AP5 谷氨酸受体 

分 类 号：R338.1[医药卫生—人体生理学]