title: Glutamatergic Kölliker-Fuse nucleus neurons innervate hypoglossal motoneurons whose axons form the medial (protruder) branch of the hypoglossal nerve in the rat.
abstract: This study was performed to understand the anatomical substrates for Kölliker-Fuse nucleus (KFN) modulation of respiratory-related tongue movement. After application of cholera toxin B subunit (CTb) to the medial branch of the hypoglossal nerve (HGn) and injection of biotinylated dextran amine (BDA) into the KFN ipsilaterally, an overlapping distribution of BDA-labeled axon terminals and CTb-labeled neurons was found in the ventral compartment of the hypoglossal nucleus (HGN) ipsilateral to the application and injection sites. At the electron microscopic level, the BDA-labeled terminals made asymmetrical synaptic contacts predominantly with dendrites of the HGN neurons, some of which were labeled with CTb. Using retrograde tracing combined with in situ hybridization, we demonstrated that almost all the KFN neurons sending their axons to the HGN were positive for vesicular glutamate transporter (VGLUT) 2 mRNA but not glutamic acid decarboxylase 67 mRNA. Using a combination of anterograde and retrograde tracing techniques and immunohistochemistry for VGLUT2, we further demonstrated that the KFN axon terminals with VGLUT2 immunoreactivity established close contact with the HGN motoneurons whose axons constitute the medial branch of the HGn. The present results suggest that glutamatergic KFN fibers may exert excitatory influence upon the HGN motoneurons sending their axons to the medial branch of the HGn for the control of protruder tongue muscles contraction to maintain airway patency during respiration.
authors: Department of Anatomy and Morphological Neuroscience, Shimane University School of Medicine, Izumo 693-8501, Japan.
authors: Shigefumi
authors: S
authors: Yokota
authors: Jian-Guo
authors: JG
authors: Niu
authors: Toshiko
authors: T
authors: Tsumori
authors: Tatsuro
authors: T
authors: Oka
authors: Yukihiko
authors: Y
authors: Yasui
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D001710:Biotin / Q000031:analogs & derivatives / Q000378:metabolism; D002772:Cholera Toxin / Q000378:metabolism; D003911:Dextrans / Q000378:metabolism; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D007002:Hypoglossal Nerve / Q000166:cytology*; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology* / Q000502:physiology; D008854:Microscopy, Electron; D009046:Motor Neurons / Q000166:cytology* / Q000502:physiology / Q000648:ultrastructure; D009474:Neurons / Q000502:physiology* / Q000648:ultrastructure; D011149:Pons / Q000166:cytology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D050599:Vesicular Glutamate Transport Protein 2 / Q000235:genetics / Q000378:metabolism
chemical_list: D003911:Dextrans; D012333:RNA, Messenger; D050599:Vesicular Glutamate Transport Protein 2; C076397:biotinylated dextran amine; D018698:Glutamic Acid; D001710:Biotin; D002772:Cholera Toxin; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1