The majority of major depression (MD) is preceded by stressful events. The stress leads to an increase in glutamate release, synthesis and release of nitric oxide (NO) as well as epigenetic changes induced by increased DNA methylation in the promoter regions of genes involved in the pathophysiology of MD. It has been demonstrated that oxidative stress and NO can modulate mediators responsible for the control of DNA methylation. However, it not known role of NO in the DNA methylation induced by stress in the brain of animals undergoing behavior test. The hypothesis of this project is that the stress induced by footshocks increase NO synthesis, which modulate the activity and/or expression of DNMTs enzymes (DNA methyltransferases) and accordingly DNA methylation in the promoter regions of genes linked behavioral stress and the neurobiology of depression. For this, rats will be submitted to the learned helplessness model and treated with inhibitors of nNOS (7-NI) or iNOS (aminoguanidine), fluoxetine or vehicle. The prefrontal cortex and hippocampus are dissected for evaluation of the global methylation, NO levels and DNMTs. At the same time, will assess the effect of NOS inhibitors and NO donors on the methylation of genes (BDNF and TrkB), and the expression of these proteins, as well as activity and DNMTs expression in primary cell culture. The results of this study may contribute to the advancement about the molecular mechanisms involved in the neurobiology of DM, enabling the identification of new biological targets of therapeutic interest in the treatment of DM.
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