L－谷氨酸及其拮抗剂对大鼠脑片旁巨细胞外侧核神经元自发放电的影响

作者在大鼠脑干脑片旁巨细胞外侧核（ＰＧＣＬ）区，用多管微电极技术观察了微电泳谷氨酸（Ｌ－Ｇｌｕ）及其拮抗剂ＤＬ－２－氨基－５－磷酸戊酸（ＡＰ５），对神经元自发放电的效应及ＡＰ５对Ｌ－Ｃｌｕ作用的影响。在５１片脑片ＰＧＣＬ区共记录１３６个自发放电稳定的神经元，主要呈重复放电样式。Ｌ－Ｇｌｕ和ＡＰ５对自发放电均有兴奋、抑制和无影响三种效应，各占所测试神经元数的８０．６５％、８．０６％、１１．２９％（Ｌ－Ｇｌｕ）和２８．００％、８．００％、６４．００％（ＡＰ５）。兴奋反应呈量效依赖关系。ＡＰ５部分地阻断部分神经元（７１．８７％）对Ｌ－Ｇｌｕ的兴奋作用。结果表明大鼠离体脑片ＰＧＣＬ区神经元自发放电样式主要是重复放电，并从细胞水平上提示ＰＧＣＬ区有起递质作用的内源性兴奋性氨基酸（ＥＡＡ），其神经元上有Ｎ－甲基－Ｄ－天冬氨酸（ＮＭＤＡ）和非ＮＭＤＡＥＡＡ受体亚型。

Effects of L-Glutamic Acid and Its Antagonist on Spontaneous Discharge of Nucleus Paragigantocellularis Lateralis Neurons in Brainstem Slice in Rat

We studied the effects of iontophoreticapplication of L-glutamic acid(L-Glu)and its antago-nist DL-2-amino-5-phosphonovaleric acid(AP5)onthe spontaneous discharge of the nucleus paragiganto-cellularis lateralis(PGCL)neurons and the influenceof AP5 on L-Glu effect in brainstem slice in rat withthe multibarrel microelectrode techniques. One hun-dred and thirty six units with stable spontaneous dis-charge were recorded in 51 rat brain slices, their dis-charge pattern being primarily a repetitive one. BothL-Glu and AP5 showed three kinds of effect on thePGCL neuronal spontaneous discharge:excitatory , in-hibitory and no-effect,with the percentage of80.65%,8.06%,11.29%for L-Glu and 28. 00%,8. 00%, 64. 00% for AP5 of the neurons tested,re-spectively. The excitatory effect showed a dose-re-sponse relationship. AP5 could block partially the exci-tatory effect of L-Glu on most neurons tested(71.87%).The results indicated that the neurons in PGCLin rat brain slice in vitro principally showed a sponta-neous dicharge with a repetitive firing pattern,andsuggested that at cellular level there existed endoge-neous excitatory amino acid as neurotransmitter in PG-CL and the neurons there possessed EAA receptors ofbotb N-methyl-D-aspartate(NMDA)and non-NMDAsubtypes.