Fundação de Amparo a Pesquisa do Estado de Minas Gerais CHAPTER II: Myosin-IIB is a non-muscle isoform in the brain with increased expression in the brains of diabetic rats. Chronic hyperglycemia caused by diabetes can impair learning and memory. Oral hypoglycemic agents such as glibenclamide have been used to control hyperglycemia. We report changes in the expression and distribution of myosin-IIB in the frontal cortex and hippocampus of diabetic rats treated with glibenclamide. To establish this, brains were harvested after 43 days of treatment with glibenclamide (6 mg/kg bw orally), homogenized and analyzed by Western blotting, qRT-PCR and immunohistochemistry. As expected, myosin-IIB expression increased in the brains of diabetic rats. However, protein levels returned to normalcy after treatment with glibenclamide. In addition, MYH10 gene expression decreased in diabetic rats treated with glibenclamide. Moreover, we found weak myosin-IIB labeling in the hippocampus and frontal cortex of rats treated with glibenclamide. Therefore, the expression of myosin-IIB is affected by diabetes mellitus and may be modulated by glibenclamide treatment in rats. Structural changes in the hippocampus and prefrontal cortex are reversible, and glibenclamide treatment may reduce patho-physiological changes in the brain. Our findings suggest a possible correlation between glibenclamide effects and myosin-IIB function in the brain of diabetised rats. CHAPTER III: Introduction: Diabetes increases oxidative stress and causes several changes in protein transport and docking of synaptic vesicles. Plant extracts have long been used to treat hyperglycemia and diabetes. Aqueous extracts of Vochysia rufa, a species endemic to the Brazilian Cerrado ecossistem, have increasingly been prescribed and used as a complementary or alternative treatment. Objective: We examined the effects of an aqueous extract of Vochysia rufa on oxidative stress markers and on the expression and localization of transport proteins and synaptic vesicle docking in the diabetic rat brain. Design/Methods: Thirty-two male Wister rats were randomly divided into 4 groups: non-diabetic, diabetic, diabetic treated with glibenclamide (6 mg / kg bw orally) and diabetic treated with Vochysia rufa extract (500 mg/kg bw orally) for forty-three days. After the treatments, brains were collected and the following parameters were evaluated: enzymatic activity of glutathione peroxidase and glutathione S-transferase, superoxide dismutase concentration, total sulfhydryl, lipid peroxidation and reduced glutathione. The levels and localization of proteins such as CaMKII, myosin-Va, synapsin-1, SNAP-25 and GLUT4 were also analyzed. Results: Vochysia rufa extract decreased SOD, GSH, TBARS and total sulfhydryl levels and increased GST levels. Additionally, myosin-Va and synapsin-1 expression decreased and levels proteins such as CaMKII and SNAP-25 increased. These results were confirmed by immunolocalization. Conclusion: The results suggest that an aqueous extract of Vochysia rufa has a neuroprotective effect on diabetic rat brains by reducing oxidative stress and controlling changes in myosin-Va and synapsin-1 expression. O diabetes aumenta o estresse oxidativo e provoca várias alterações no transporte de proteínas e de ancoragem das vesículas sinápticas. Os extratos de plantas têm sido muito utilizados para tratar a hiperglicemia e diabetes. Extratos aquosos de Vochysia rufa, uma espécie do Cerrado brasileiro, têm sido prescritos e utilizados como tratamento complementar ou alternativo. Foram analisados os efeitos do extrato aquoso de Vochysia rufa sobre marcadores de estresse oxidativo e na expressão e localização de proteínas de transporte e ancoragem das vesículas sinápticas no cérebro de ratos diabéticos. Trinta e dois ratos Wistar machos foram divididos aleatoriamente em 4 grupos: não-diabéticos, diabéticos, diabéticos tratados com glibenclamida (6 mg/kg de peso corporal por via oral) e diabéticos tratados com extrato de Vochysia rufa (500 mg/kg de peso corporal por via oral) por 43 dias. Após os tratamentos, os cérebros foram coletadas e os seguintes parâmetros foram avaliados: atividade enzimática da glutationa peroxidase e glutationa S- transferase, a concentração de superóxido dismutase, sulfidrila total, a peroxidação lipídica e de glutationa reduzida. Os níveis e localização de proteínas, como CaMKII, miosina - Va, sinapsina -1, SNAP -25 e GLUT4 também foram analisados. O extrato de Vochysia rufa diminuiu SOD, GSH, TBARS e os níveis totais de sulfidrila e aumentou os níveis de GST. Além disso, a miosina -Va e sinapsina -1 apresentaram os níveis de expressão diminuídas, ao contrário de CaMKII e SNAP-25 que aumentaram. Estes resultados foram confirmados por imunohistoquímica. Os resultados sugerem que o extrato aquoso de Vochysia rufa tem um efeito neuroprotetor em cérebros de ratos diabéticos, reduzindo o estresse oxidativo e controlando as mudanças na miosina -Va e sinapsina -1. Mestre em Genética e Bioquímica