title: Colocalization of neuronal nitric oxide synthase with GABA in rat cuneate nucleus.
abstract: Pre- and post-embedding immunocytochemistry were employed in this electron microscopic investigation of cuneate neurons that are enriched in GABA and in nitric oxide synthase, the enzyme responsible for the synthesis of nitric oxide. GABAergic neurons are local circuit interneurons; 10-20% of them also contain nitric oxide synthase. These are among the smallest GABA-positive perikarya. We describe a network of processes in the rat cuneate nucleus that are immunopositive for nitric oxide synthase. Axon terminals positive for nitric oxide synthase are small and make synapses mainly onto dendrites; they make only occasional axo-axonic contacts. Double-labelling immunocytochemistry verified that the large majority of terminals positive for nitric oxide synthase also contained GABA. However, most GABA-positive profiles were negative for nitric oxide synthase and GABA-positive terminals that are negative for nitric oxide synthase frequently made axo-axonic contacts. These results suggest that nitric oxide synthase is within a specialized subpopulation of interneurons in the cuneate nucleus.
authors.affiliation: Department of Cell Biology and Anatomy, School of Medicine, University of North Carolina at Chapel Hill 27599, USA.
authors.forename: J G
authors.initials: JG
authors.lastname: Valtschanoff
authors.forename: R J
authors.initials: RJ
authors.lastname: Weinberg
authors.forename: A
authors.initials: A
authors.lastname: Rustioni
authors.forename: H H
authors.initials: HH
authors.lastname: Schmidt
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000032:analysis*; D000818:Animals; D001369:Axons / Q000201:enzymology / Q000648:ultrastructure; D007395:Interneurons / Q000737:chemistry / Q000648:ultrastructure; D008297:Male; D008526:Medulla Oblongata / Q000737:chemistry* / Q000166:cytology; D016253:Microscopy, Immunoelectron; D009419:Nerve Tissue Proteins / Q000032:analysis*; D019001:Nitric Oxide Synthase; D051381:Rats; D017207:Rats, Sprague-Dawley; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
chemical_list: D009419:Nerve Tissue Proteins; D005680:gamma-Aminobutyric Acid; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases