A local GABAergic system within rat trigeminal ganglion cells

H. Hayasaki, Y. Sohma, K. Kanbara, K. Maemura, T. Kubota, M. Watanabe

研究成果: Article査読

63 被引用数 (Scopus)

抄録

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 GABAA receptor subunits α1-6, β1-3, γ1-3, and δ. 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. GABAA receptor α1, α5, β2/3 and γ1/2/3 subunit immunoreactivities were observed in the majority of neurons, but no immunoreactivity for α2 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 α3, α4, α6, and δ subunits appeared to be dependent on cell size, as δ and α6 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 μm, 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.

本文言語English
ページ(範囲)745-757
ページ数13
ジャーナルEuropean Journal of Neuroscience
23
3
DOI
出版ステータスPublished - 2006 2月
外部発表はい

ASJC Scopus subject areas

  • 神経科学(全般)

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