Nitric oxide production is associated to increased lipoperoxidation and active caspase-3 in demyelinated brain regions of the taiep rat

We previously showed that the increase in nitric oxide (NO) levels and NO synthase (NOS) expression correlate with the progression of reactive astrocytosis and demyelination in the brains of 6-month-old taiep rats. Increased levels of NO can result in high concentration of peroxynitrite and thus cause tissue damage, which consists of lipoperoxidation of the cytoplasmic membrane, such as the myelin, and of apoptotic and necrotic cell-death. On this basis, we studied whether the increased NO production is associated with lipoperoxidation and cell death in the cerebellum and brainstem over the age (1, 3, 6, and 8 months) of taiep rats. The results were compared with those obtained in matched Sprague-Dawley (SD) rats. We measured the levels of nitrites (NO production), malonyldialdehyde, and 4-hydroxyalkenal (lipoperoxidation) in brain tissue homogenates. The three NOS isoforms and cleaved caspase-3 were evaluated by using ELISA and immunostaining techniques. Our results showed that NO production and lipoperoxidation increased in the cerebellum and brainstem as the age of the taiep rats increased compared to SD rats. The overexpression of nNOS and iNOS were in the Purkinje cells, magnocellular neurons, and in oligodendrocytes, whereas the glial cells showed strong cleaved-caspase-3 immunoreactivity. In summary our results suggest that NO plays a role in the demyelination and cell death in the taiep rat.