title: Ultrastructural localization of neuronal nitric oxide synthase in the laterodorsal tegmental nucleus of wild-type and knockout mice.
abstract: The cellular and subcellular distribution of neuronal nitric oxide synthase and its related reduced beta-nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity was compared in wild-type and homozygous knockout mice, in which the gene for neuronal nitric oxide synthase has been disrupted, resulting in a lack of the predominant splice isoform alpha. In the laterodorsal tegmental nucleus, used as a model structure, the cholinergic principal neurons also exhibited an intensive neuronal nitric oxide synthase immunoreactivity. Using the tetrazolium salt 2-(2-benzothiazolyl)-5-styryl-3-(4'-phthalhydrazidyl)-tetrazo++ +-lium chloride (BSPT), these neurons were filled with NADPH-diaphorase reaction product, whereas the equivalent neurons of knockout mice showed, if at all, only traces of neuronal nitric oxide synthase immunoreactivity in parallel to a diminished NADPH-diaphorase labelling. Subcellularly, the neuronal nitric oxide synthase-related diaminobenzidine product was, apparently owing to diffusion artifact, more or less evenly distributed in the cytosol of the neuronal perikarya and dendrites of wild-type mice. In contrast, the BSPT reaction product formazan was closely and discretely attached to endocellular membranes. In the intensely NADPH-diaphorase stained neurons of wild-type mice, 85% of the mitochondria were, at least partly, labelled for BSPT-formazan, whilst in the equivalent neurons of mutant mice, only 13% of mitochondria were NADPH-diaphorase positive. Related to the NADPH-diaphorase activity in the principal neurons of wild-type mice, only 10% of membranes of the endoplasmic reticulum, 27% of mitochondrial membranes and 26% of the nuclear envelope exhibited NADPH-diaphorase activity in the mutant mice. Our findings with the BSPT histochemistry suggest that residues of NADPH-diaphorase positivity in mutant mice are attributed to the alternative splice isoforms beta and/or gamma of neuronal nitric oxide synthase. The splice isoform a is located predominantly at the membranes of the endoplasmic reticulum.
authors.affiliation: Institute of Medical Neurobiology, University of Magdeburg, Germany. fritz.rothe@medizin.uni-magdeburg.de
authors.forename: F
authors.initials: F
authors.lastname: Rothe
authors.forename: P L
authors.initials: PL
authors.lastname: Huang
authors.forename: G
authors.initials: G
authors.lastname: Wolf
mesh_terms: D000818:Animals; D002795:Choline O-Acetyltransferase / Q000032:analysis; D005455:Fluorescent Antibody Technique; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008854:Microscopy, Electron; D009252:NADPH Dehydrogenase / Q000032:analysis; D009474:Neurons / Q000201:enzymology* / Q000648:ultrastructure; D019001:Nitric Oxide Synthase / Q000032:analysis / Q000235:genetics*; D052248:Nitric Oxide Synthase Type I; D013681:Tegmentum Mesencephali / Q000166:cytology / Q000201:enzymology*
chemical_list: D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496321:Nos1 protein, mouse; D009252:NADPH Dehydrogenase; D002795:Choline O-Acetyltransferase