Glutamatergic pathways from the Kölliker-Fuse nucleus to the phrenic nucleus in the rat.
After ipsilateral injections of biotinylated dextran amine (BDA) into the Kölliker-Fuse (KF) nucleus and cholera toxin B subunit (CTb) into the ventral horn in C4 to C5 segments of the spinal cord, an overlapping distribution of BDA-labeled axon terminals and CTb-labeled neurons was found in the rostral ventral respiratory group (rVRG) region ipsilateral to the injection sites. After ipsilateral injections of BDA into the KF and Fluoro-Gold (FG) into the ventral horn in C4 to C5 segments of the spinal cord, BDA-labeled axons were found to make asymmetrical synapses with the somata and dendrites of FG-labeled neurons within the neuropil of the rVRG region. Using retrograde tracing combined with immunohistochemistry for phosphate-activated glutaminase (PAG), we observed that as many as 72% of the rVRG neurons projecting to the PhN were immunoreactive for PAG and that approximately 62% and 75% of the KF neurons projecting respectively to the rVRG region and PhN contain PAG immunoreactivity. Using anterograde tracing combined with immunohistochemistry for vesicular glutamate transporter 2 (VGluT2), we further demonstrated that the KF axon terminals in the rVRG and PhN regions as well as the rVRG axon terminals in the PhN region contain VGluT2 immunoreactivity. The present results suggest that the glutamatergic pathways from the KF to the PhN directly and indirectly via the rVRG region may exist and underlie the inspiratory responses that are elicited by activation of the KF neurons.
Yokota
Shigefumi
S
Department of Anatomy and Morphological Neuroscience, Shimane Medical University, Izumo 693-8501, Japan.
Tsumori
Toshiko
T
Ono
Katsuhiko
K
Yasui
Yukihiko
Y
D000818:Animals; D001370:Axonal Transport / Q000502:physiology; D001710:Biotin / Q000031:analogs & derivatives*; D002352:Carrier Proteins / Q000378:metabolism; D002772:Cholera Toxin; D003911:Dextrans; D005456:Fluorescent Dyes; D018698:Glutamic Acid / Q000378:metabolism*; D005972:Glutaminase / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000502:physiology; D026901:Membrane Transport Proteins; D008854:Microscopy, Electron; D009046:Motor Neurons / Q000502:physiology / Q000648:ultrastructure; D009434:Neural Pathways / Q000502:physiology / Q000648:ultrastructure*; D010791:Phrenic Nerve / Q000502:physiology / Q000648:ultrastructure*; D011149:Pons / Q000166:cytology* / Q000502:physiology; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D012125:Respiratory Center / Q000166:cytology* / Q000502:physiology; D012143:Respiratory Physiological Phenomena; D013116:Spinal Cord / Q000502:physiology / Q000648:ultrastructure*; D013266:Stilbamidines; D009435:Synaptic Transmission / Q000502:physiology; D050599:Vesicular Glutamate Transport Protein 2; D033921:Vesicular Transport Proteins
C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D002352:Carrier Proteins; D003911:Dextrans; D005456:Fluorescent Dyes; D026901:Membrane Transport Proteins; C493475:Slc17a6 protein, rat; D013266:Stilbamidines; D050599:Vesicular Glutamate Transport Protein 2; D033921:Vesicular Transport Proteins; C076397:biotinylated dextran amine; D018698:Glutamic Acid; D001710:Biotin; D002772:Cholera Toxin; D005972:Glutaminase