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KMID : 0848120050300020071
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International Journal of Oral Biology
2005 Volume.30 No. 2 p.71 ~ p.76
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GABAergic Synaptic Input to Mesencephalic Trigeminal Neurons in Rat
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Ryu Hyo-Chel
Piao Zheng-Gen
Choi Se-Young
Lee Sung-Joong
Park Kyung-Pyo
Kim Joong-Soo
Oh Seog-Bae
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Abstract
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The mesencephalic trigeminal nucleus (Mes V) contains cell bodies of primary afferent sensory neurons that relay proprioceptive information from the periodontium and masticatory muscles and function as typical sensory neurons or potentially as integrative interneurons. In the present study, we studied these two potential functions using combined experimental approaches of retrograde labeling and whole cell patch clamp recording. Mes V neurons that presumably originate from periodontal nerve fibers in subsets of Mes V nucleus were identified by retrograde labeling with a fluorescent dye, DiI, which was applied onto inferior alveolar nerve. These cells were elliptical perikarya shaped cells about 40 μm in diameter. In these neurons, we measured high voltage-activated calcium channel (HVACC) currents. GABA_(B) agonist, baclofen, inhibited calcium currents, and the HVACC currents inhibition by baclofen was voltage-dependent, exhibited prepulse facilitation, indicating that it was mediated by G_(i)/G_(o) protein. Taken together, our results demonstrate that Mes V neurons not only have cell bodies originating from periodontium, but also receive synaptic inputs including GABAergic neurons suggesting that Mes V neurons function as both primary sensory neurons and integrative interneurons.
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KEYWORD
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mesencephalic trigeminal nucleus, retrograde labeling, Dil whole-cell patch clamp recording, calcium currents
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