The role of free radicals in canine counterpart of senile dementia of the Alzheimer type.

The pathogenesis of Alzheimer's disease is still unknown. In recent time oxidative stress has been discussed as an important contributor. In the present study we investigated the role of free radicals in the spontaneous canine model of Alzheimer's disease. We analysed end-products of lipid peroxidation: lipofuscin-like pigments (LFP), protein carbonyls, and vitamin E to obtain data on oxidative damage in brain of demented dogs. When the generation of free radicals is intensive the toxic products of lipid peroxidation can diffuse from the site of the primary formation and merge with erythrocytes. Therefore we also determined the level of lipid peroxidation in red blood cells. In brain of demented animals the level of LFP increased (to 247%, P<0.05) as well as of protein carbonyls (to 438%, P<0.01) while the vitamin E concentration was lowered (to 34%, P<0.01) when compared to age-matched non-demented controls. The end-products of lipid peroxidation have been found increased also in erythrocytes of demented dogs (250%, P<0.05). These results indicate intensive production of free radicals in brain of animals with dementia which induces damage to erythrocytes. Detection of the specific products of free radical damage in blood samples could be used for diagnostic purposes.