Axon terminals expressing vesicular glutamate transporter VGLUT1 or VGLUT2 within the trigeminal motor nucleus of the rat: Origins and distribution patterns |
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Authors: | You‐Wang Pang Shun‐Nan Ge Kouichi C. Nakamura Jin‐Lian Li Kang‐Hui Xiong Takeshi Kaneko Noboru Mizuno |
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Affiliation: | 1. Department of Anatomy and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an 710032, China;2. Department of Orthopaedics, the 180th Hospital of the People's Liberation Army, Quanzhou 362000, China;3. The first three authors contributed equally to this work.;4. Department of Morphological Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606‐8501, Japan;5. Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency, Kawaguchi 332‐0012, Japan |
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Abstract: | Little is known about the significance of the two types of glutamatergic neurons (those expressing vesicular glutamate transporter VGLUT1 or VGLUT2) in the control of jaw movements. We thus examined the origin and distribution of axon terminals with VGLUT1 or VGLUT2 immunoreactivity within the trigeminal motor nucleus (Vm) in the rat. The Vm was divided into the dorsolateral division (Vm.dl; jaw‐closing motoneuron pool) and the ventromedial division (Vm.vm; jaw‐opening motoneuron pool). VGLUT1‐immunopositive terminals were seen within the Vm.dl only, whereas VGLUT2‐immunopositive ones were distributed to both the Vm.dl and the Vm.vm. Transection of the motor root eliminated almost all VGLUT1‐immunopositive axons in the Vm.dl, with no changes of VGLUT2 immunoreactivity in the two divisions, indicating that the VGLUT1‐ and VGLUT2‐immunopositive axons came from primary afferents in the mesencephalic trigeminal nucleus and premotor neurons for the Vm, respectively. In situ hybridization histochemistry revealed that VGLUT2 neurons were much more numerous than VGLUT1 neurons in the regions corresponding to the reported premotoneuron pool for the Vm. The results of immunofluorescence labeling combined with anterograde tract tracing further indicated that premotor neurons with VGLUT2 in the trigeminal sensory nuclei, the supratrigeminal region, and the reticular region ventral to the Vm sent axon terminals contacting trigeminal motoneurons and that some of the VGLUT1‐expressing premotor neurons in the reticular region ventral to the Vm sent axon terminals to jaw‐closing motoneurons. The present results suggested that the roles played by glutamatergic neurons in controlling jaw movements might be different between VGLUT1‐ and VGLUT2‐expressing neurons. J. Comp. Neurol. 512:595–612, 2009. © 2008 Wiley‐Liss, Inc. |
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Keywords: | masticatory motoneurons premotor neurons glutamatergic neurons immunohistochemistry in situ hybridization electron microscopy |
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