Neuronal Nitric Oxide Synthase Alternatively Spliced Forms: Prominent Functional Localizations in the Brain

• Published in: Proceedings of the National Academy of Sciences - PNAS 1997-04, Vol.94 (7), p.3396-3401
• Main Authors: Mikael J. L. Eliasson, Blackshaw, Seth, Schell, Michael J., Snyder, Solomon H.
• Format: Article
• Language: English
• Subjects: Alternative Splicing; Amino acids; Animals; Antibodies - immunology; Antiserum; Biological Sciences; Brain; Brain - cytology; Brain - enzymology; Catalytic activity; Citrulline - immunology; Cochlear nucleus; Exons; Immunohistochemistry; In Situ Hybridization; Messenger RNA; Mice; Neurology; Neurons; Neurons - enzymology; Nitric Oxide Synthase - genetics; RNA, Messenger - genetics; RNA, Messenger - metabolism; Rodents
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.7.3396

Neuronal nitric-oxide synthase (nNOS) is subject to alternative splicing. In mice with targeted deletions of exon 2 (nNOSΔ /Δ), two alternatively spliced forms, nNOSβ and γ , which lack exon 2, have been described. We have compared localizations of native nNOSα and nNOSβ and γ by in situ hybridization and immunohistochemistry in wild-type and nNOSΔ /Δmice. To assess nNOS catalytic activity in intact animals we localized citrulline, which is formed stoichiometrically with NO, by immunohistochemistry. nNOSβ is prominent in several brain regions of wild-type animals and shows 2-to 3-fold up-regulation in the cortex and striatum of nNOSΔ /Δanimals. The persistence of much nNOS mRNA and protein, and distinct citrulline immunoreactivity (cit-IR) in the ventral cochlear nuclei and some cit-IR in the striatum and lateral tegmental nuclei, indicate that nNOSβ is a major functional form of the enzyme in these regions. Thus, nNOSβ , and possibly other uncharacterized splice forms, appear to be important physiological sources of NO in discrete brain regions and may account for the relatively modest level of impairment in nNOSΔ /Δanimals.