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Neuronal nitric oxide synthase alternatively spliced forms: prominent functional localizations in the brain
M J Eliasson1, S Blackshaw, M J Schell
1Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Summary
Neuronal nitric-oxide synthase (nNOS) beta is a significant functional form in the brain, even in mice lacking exon 2. This splice variant contributes to nitric oxide (NO) production in specific brain regions.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Neuronal nitric-oxide synthase (nNOS) exists in multiple alternatively spliced forms.
- nNOS beta and gamma are splice variants lacking exon 2.
- The functional significance of these splice variants in vivo remains largely uncharacterized.
Purpose of the Study:
- To compare the localization of nNOS alpha, nNOS beta, and nNOS gamma in wild-type and nNOS(delta/delta) mice.
- To assess the catalytic activity of nNOS by localizing citrulline, a byproduct of NO synthesis.
- To determine the physiological role of nNOS beta in discrete brain regions.
Main Methods:
- In situ hybridization to detect nNOS mRNA.
- Immunohistochemistry to localize nNOS protein and citrulline.
- Comparison of wild-type and nNOS(delta/delta) mouse models.
Main Results:
- nNOS beta is abundant in several brain regions of wild-type mice.
- nNOS beta shows a 2-to 3-fold increase in the cortex and striatum of nNOS(delta/delta) mice.
- Distinct citrulline immunoreactivity in specific brain nuclei indicates functional nNOS beta activity.
Conclusions:
- nNOS beta is a major functional form of nNOS in discrete brain regions, such as the ventral cochlear nuclei.
- nNOS beta contributes significantly to nitric oxide (NO) production in the brain.
- Uncharacterized nNOS splice forms may also play important physiological roles, explaining the modest impairment in nNOS(delta/delta) mice.