title: Immunocytochemical localization of sodium channels in an insect central nervous system using a site-directed antibody.
abstract: Antibodies to channel proteins and specific peptide sequences have been previously used to localize voltage-activated sodium channels in the rat brain. Here we describe the first localization of sodium channels in an insect nervous system using a site-directed antibody. The mesothoracic ganglion of the cockroach was stained with an antibody to the highly conserved SP19 sequence. Antibody labelling was visualized by light microscopy using the avidin/biotin method on wax sections, and transmission electron microscopy of immunogold-labelled thin sections. Central ganglia of insects contain clearly separated regions of cell bodies, synaptic neuropil, axon tracts, and nerves. Antibody staining by light microscopy was limited to neurons, and was intense in axons throughout the ganglion and nerves. Staining was also strong in the cytoplasm, but not the nuclei, of many neuronal cell bodies. Neuropil regions were relatively lightly labelled. These findings can be correlated with the known electrophysiology of the ganglion. Electron microscopy detected sodium channels in areas surrounding axons, probably including axon membranes and enveloping glial cell membranes. Axonal mitochondria were also heavily labelled, suggesting a sodium channel transport function for these organelles.
authors.affiliation: Department of Physiology, University of Alberta, Edmonton, Canada.
authors.forename: A S
authors.initials: AS
authors.lastname: French
authors.forename: E J
authors.initials: EJ
authors.lastname: Sanders
authors.forename: E
authors.initials: E
authors.lastname: Duszyk
authors.forename: S
authors.initials: S
authors.lastname: Prasad
authors.forename: P H
authors.initials: PH
authors.lastname: Torkkeli
authors.forename: J
authors.initials: J
authors.lastname: Haskins
authors.forename: R A
authors.initials: RA
authors.lastname: Murphy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002490:Central Nervous System / Q000033:anatomy & histology / Q000378:metabolism*; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000276:immunology / Q000378:metabolism*; D016612:Paraffin Embedding; D010526:Periplaneta / Q000033:anatomy & histology / Q000378:metabolism*; D015222:Sodium Channels / Q000276:immunology / Q000378:metabolism*
chemical_list: D009479:Neuropeptides; C084080:SP19 peptide, type I sodium channel; D015222:Sodium Channels