Nitric oxide synthase 3-mediated neurodegeneration after intracerebral gene delivery

In Alzheimer disease (AD), increased nitric oxide synthase 3 (NOS3) expression correlates with apoptosis in cortical neurons and colocalizes with amyloid precursor protein (APP)-ainyloid beta (A beta) deposits in the brain. In the present stud, we examined the potential role of NOS3 in relation to AD-type neurodegeneration using an in vivo model of gene delivery. Long Evans rat pups were given a single intracerebral injection of recombinant plasmid DNA containing the human NOS3 cDNA (p-hNOS3) or the luciferase (p-Luc) gene as a negative control, and complexed with polyamine reagent. Overexpression of NOS3 in the brain increased,the levels of APP, APP-A beta, p53, Tau, glial fibrillary acidic protein, and peroxisome prolit'erator activated receptors (PPAR) delta and gamma and decreased the levels of Hit (neuronal marker) mRNA, phosphorylated glycogen synthase kinase 3 beta, ATP synthase, and choline acetyltransferase expression as demonstrated by real-time quantitative reverse-transcribed polymerase chain reaction, Western blot analysis, or immunohistochemical staining. These effects of NOS3 overexpression were accompanied by increased single-stranded DNA immunoreactivity, reflecting DNA damage. The results suggest that increased cerebral expression of NOS3 causes several molecular abnormalities related to AD-type neurodegeneration, including oxidative stress, mitochondrial dysfunction, and impaired acetylcholine bomeostasis. The coexisting increases in PPAR-delta and -gamma expression suggest that the adverse effects of NOS3 overexpression may be abated by PPAR agonist treatment.