title: Efferent function of vestibular afferent endings? Similar localization of N-type calcium channels, synaptic vesicle and synaptic membrane-associated proteins.
abstract: We investigated the distribution of N-type voltage-dependent calcium channels that mediate Ca(2+) entry initiating transmitter release in the rat vestibular sensory epithelium. We used confocal microscopy to assess the in vitro labeling by fluorescent specific ligand binding, omega-conotoxin-GVIA and also the immunolabeling of presynaptic soluble N-ethylmaleimide-sensitive fusion factor attachment protein receptor (SNARE) proteins, syntaxin, 25,000 mol. wt synaptosome-associated protein and synaptotagmin: components of the neurotransmitter exocytosis machinery. We found that there was a close anatomical association between the voltage-gated calcium channels, the synaptic vesicle and synaptic membrane-associated proteins on the afferent nerve calyces and probably afferent boutons, which are postsynaptic compartments. Our data suggest that these peripheral afferent endings possess the presynaptic Ca(2+) channels and the components of the presynaptic SNARE proteins involved in synaptic vesicle docking and calcium-dependent exocytosis. They provide additional evidence for a secretory function and efferent role of these endings in hair cell neurotransmission.
authors.affiliation: Inserm U 432, UM 2, Place E. Bataillon, 34095 Cedex 05, Montpellier, France. dememes@univ-montp2.fr
authors.forename: D
authors.initials: D
authors.lastname: Demêmes
authors.forename: A
authors.initials: A
authors.lastname: Seoane
authors.forename: S
authors.initials: S
authors.lastname: Venteo
authors.forename: G
authors.initials: G
authors.lastname: Desmadryl
mesh_terms: D000344:Afferent Pathways / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D020864:Calcium Channels, N-Type / Q000235:genetics / Q000378:metabolism*; D002135:Calcium-Binding Proteins; D005089:Exocytosis / Q000502:physiology; D018069:Hair Cells, Vestibular / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism; D009924:Organ Culture Techniques; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D050765:Qa-SNARE Proteins; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D050600:SNARE Proteins; D013570:Synaptic Membranes / Q000378:metabolism* / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D050825:Synaptosomal-Associated Protein 25; D050857:Synaptotagmins; D033921:Vesicular Transport Proteins; D014725:Vestibular Nerve / Q000166:cytology / Q000378:metabolism*; D014722:Vestibule, Labyrinth / Q000166:cytology / Q000378:metabolism
chemical_list: D020864:Calcium Channels, N-Type; D002135:Calcium-Binding Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D050765:Qa-SNARE Proteins; D012333:RNA, Messenger; D050600:SNARE Proteins; C494210:Snap25 protein, rat; D050825:Synaptosomal-Associated Protein 25; D033921:Vesicular Transport Proteins; D050857:Synaptotagmins