A local GABAergic system within rat trigeminal ganglion cells
A local GABAergic system within rat trigeminal ganglion cells
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DOI：
10.1111/j.1460-9568.2006.04602.x
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发表时间：
2006-02-01
影响因子：
3.4
通讯作者：
Watanabe, M
中科院分区：
文献类型：
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作者：
Hayasaki, H;Sohma, Y;Watanabe, M
我们研究了Sprague-Dawley大鼠（2-3周龄）三叉神经节（TG）内的GABA能系统。逆转录-聚合酶链反应（RT-PCR）分析显示谷氨酸脱羧酶（GAD）65和GAD 67 mRNA以及编码GABA（A）受体亚单位α 1-6、β 1-3、γ 1-3和δ的mRNA的表达。原位杂交显示GAD 65和GAD 67 mRNA在神经元胞体中表达，而在卫星细胞中不表达。免疫组织化学分析表明，只有GAD 65在所有的神经元细胞体中表达，约70%的所有神经元表现出GABA免疫反应。卫星细胞GABA免疫阳性。GABA（A）受体α 1、α 5、β 2/3和γ 1/2/3亚单位在大多数神经元中观察到免疫反应，但未观察到α 2的免疫反应。根据细胞大小和形态，在TG中鉴定出两种类型的细胞，A型和B型。表达α 3、α 4、α 6和δ亚基的细胞百分比似乎取决于细胞大小，因为δ和α 6表达仅在小（B型）神经元中观察到。在全细胞膜片钳实验中，GABA的应用诱导内向氯电流在所有的神经元检查。GABA的EC 50为5.3 - 240 μ m，希尔系数（nH）在-60 mV时为0.98 - 2.6。我们发现，GABA被释放从TG细胞通过增加细胞外K+浓度到100毫米。我们推测，GABA作为一种非突触释放的扩散性神经递质，这可能会调节体细胞内的TG神经元抑制。
We investigated the GABAergic system within the Sprague-Dawley rat (2-3-weeks old) trigeminal ganglion (TG). Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed expression of glutamate decarboxylase (GAD) 65 and GAD67 mRNAs and mRNAs encoding GABA(A) receptor subunits alpha 1-6, beta 1-3, gamma 1-3, and delta. In situ hybridization revealed that GAD65 and GAD67 mRNAs were expressed in neuronal cell bodies but not satellite cells. Immunohistochemical analysis showed that only GAD65 was expressed in all neuronal cell bodies, and approximately 70% of all neurons exhibited GABA immunoreactivity. Satellite cells were strongly immunopositive for GABA. GABA(A) receptor alpha 1, alpha 5, beta 2/3 and gamma 1/2/3 subunit immunoreactivities were observed in the majority of neurons, but no immunoreactivity for alpha 2 was observed. Two types of cells were identified in TG based on cell size and morphology, type A and B. The percentage of cells expressing alpha 3, alpha 4, alpha 6, and delta subunits appeared to be dependent on cell size, as delta and alpha 6 expression were only observed in small (B-type) neurons. In whole-cell patch clamp experiments, GABA application induced inward Cl- currents in all neurons examined. The EC50 for GABA varied from 5.3 to 240 mu m, and the Hill Coefficient (nH) varied between 0.98 and 2.6 at -60 mV. We found that GABA was released from TG cells by increasing extracellular K+ concentration to 100 mm. We speculate that GABA acts as a nonsynaptically released diffusible neurotransmitter, which may modulate somatic inhibition of neurons within the TG.