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ISSN : 1226-7155(Print)
ISSN : 2287-6618(Online)
International Journal of Oral Biology Vol.30 No.2 pp.71-76

GABAergic Synaptic Input to Mesencephalic Trigeminal Neurons in Rat

Joong-Soo,Kim , Seog-Bae, Oh, Ryu Hyo-Chel, Piao Zheng Gen, Choi Se-Young, Lee Sung-Joong, Park Kyung-Pyo
Department of Physiology, College of Dentistry and Dental Research Institute, Seoul National University


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 40μmin diameter. In these neurons, we measured high voltage-activated calcium channel (HVACC) currents GABAв 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;/Go 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.