Investigation of the involvement of oxidative stress in animal models of muscular dystrophy

Abstract

Muscular dystrophy is characterized by a progressive degeneration, mainly of skeletal muscle (Cohn e Campbell, 2000). Most types of dystrophies are related with mutations in genes encoding proteins belonging to the dystrophin-glycoprotein complex, responsible to maintain the integrity and stability of cells that comprise the skeletal muscle (Crosbie, 1999). Even before the identification of these mutations, the involvement of oxidative stress with muscular dystrophy was proposed (Binder e col., 1965). Alterations in the muscle structure could give rise to pathological production of free radicals that would lead to disruption of regulatory systems provoking muscle degeneration (Tidball e Wehling-Henricks, 2007). Neuronal nitric oxide synthase (nNOS) is also associated with the dystrophin-glycoprotein complex. Therefore, alterations in the dystrophin-glycoprotein complex cause the displacement of nNOS and probably the irregular generation of nitric oxide. Consequently, it is expected that signaling processes should also be altered (Stamler e Meissner, 2001). In this proposal, we intend to characterize the involvement of oxidative stress in muscle dystrophy. Oxidative stress markers such as GSH/GSSG ratio and protein carbonyls will be determined in muscle of animal models of dystrophy. We will also study the role of nitric oxide in this pathology by western blot assays against nNOS and detection of nitric oxide generation. The mouse mdx (which carries a mutation in the dystrophin gene) and largemyd (which carries a mutation in the glycosyltransferase gene) will be studied in these work. To a better evaluation of the role of nitric oxide in this animal models we will try to inactivate nNOS using the technique of RNA interference (RNAi). Phenotype analyses of these animals will also be analyzed and correlated with the oxidative stress data. Eventually, antioxidant intervention can be carried out. (AU)