Reduction of oxidative stress improves insulin signaling in cardiac tissue of obese mice.

OBJECTIVE: To evaluate the effects of oxidative stress on insulin signaling in cardiac tissue of obese mice. METHODS: Thirty Swiss mice were equally divided (n=10) into three groups: Control Group, Obese Group, and Obese Group Treated with N-acetylcysteine. After obesity and insulin resistance were established, the obese mice were treated with N-acetylcysteine at a dose of 50mg/kg daily for 15 days via oral gavage. RESULTS: Higher blood glucose levels and nitrite and carbonyl contents, and lower protein levels of glutathione peroxidase and phosphorylated protein kinase B were observed in the obese group when compared with their respective control. On the other hand, treatment with N-acetylcysteine was effective in reducing blood glucose levels and nitrite and carbonyl contents, and significantly increased protein levels of glutathione peroxidase and phosphorylated protein kinase B compared to the Obese Group. CONCLUSION: Obesity and/or a high-lipid diet may result in oxidative stress and insulin resistance in the heart tissue of obese mice, and the use of N-acetylcysteine as a methodological and therapeutic strategy suggested there is a relation between them.

Reduction of oxidative stress improves insulin signaling in cardiac tissue of obese mice / Redução do estresse oxidativo melhora a sinalização da insulina em tecido cardíaco de camundongos obesos

ABSTRACT Objective To evaluate the effects of oxidative stress on insulin signaling in cardiac tissue of obese mice. Methods Thirty Swiss mice were equally divided (n=10) into three groups: Control Group, Obese Group, and Obese Group Treated with N-acetylcysteine. After obesity and insulin resistance were established, the obese mice were treated with N-acetylcysteine at a dose of 50mg/kg daily for 15 days via oral gavage. Results Higher blood glucose levels and nitrite and carbonyl contents, and lower protein levels of glutathione peroxidase and phosphorylated protein kinase B were observed in the obese group when compared with their respective control. On the other hand, treatment with N-acetylcysteine was effective in reducing blood glucose levels and nitrite and carbonyl contents, and significantly increased protein levels of glutathione peroxidase and phosphorylated protein kinase B compared to the Obese Group. Conclusion Obesity and/or a high-lipid diet may result in oxidative stress and insulin resistance in the heart tissue of obese mice, and the use of N-acetylcysteine as a methodological and therapeutic strategy suggested there is a relation between them.

RESUMO Objetivo Avaliar os efeitos do estresse oxidativo sobre a sinalização da insulina em tecido cardíaco de camundongos obesos. Métodos Utilizaram-se 30 camundongos Swiss subdivididos igualmente (n=10) em três grupos: Grupo Controle, Grupo Obeso e Grupo Obeso Tratado com N-acetilcisteína. Após estabelecidas a obesidade e a resistência à insulina, os camundongos obesos foram tratados diariamente, durante 15 dias, via gavagem oral, com N-acetilcisteína na dose de 50mg/kg. Resultados Observaram-se maiores níveis de glicose sanguínea, conteúdos de nitrito e carbonil, e menores níveis proteicos de glutationa peroxidase e proteína quinase B fosforilada no Grupo Obeso quando comparado a seu respectivo controle. Por outro lado, o tratamento com N-acetilcisteína se mostrou eficiente em diminuir os níveis glicêmicos, os conteúdos de nitrito e carbonil, e aumentar significativamente os níveis proteicos de glutationa peroxidase e proteína quinase B fosforilada, quando comparados ao Grupo Obeso. Conclusão Obesidade e/ou dieta hiperlipídica levam a estresse oxidativo e à resistência à insulina no tecido cardíaco de camundongos obesos, e o uso da N-acetilcisteína como estratégia metodológica e terapêutica sugeriu haver relação entre ambos.

Cigarette smoke exposure induces ROS-mediated autophagy by regulating sestrin, AMPK, and mTOR level in mice.

Many pathological conditions linked to cigarette smoking are caused by the production of reactive oxygen species (ROS). The present study was conducted to analyze the effect of ROS on the lungs of Swiss mice exposed to cigarette smoking, focusing on autophagy-mediated mechanisms, and investigate the involvement of SESN2, AMPK, and mTOR signaling. Mice were exposed to cigarette smoke (CS) for 7, 15, 30, 45, and 60 days; the control group was not exposed to CS. Only mice exposed to CS for 45 days were selected for subsequent N-acetylcysteine (NAC) supplementation and smoke cessation analyses. Exposure to CS increased the production of ROS and induced molecular changes in the autophagy pathway, including an increase in phosphorylated AMPK and ULK1, reduction in phosphorylated mTOR, and increases in SESN2, ATG12, and LC3B levels. NAC supplementation reduced ROS levels and reversed all molecular changes observed upon CS treatment, suggesting the involvement of oxidative stress in inducing autophagy upon CS exposure. When exposure to CS was stopped, there were decreases in the levels of oxidative stress, AMPK and ULK1 phosphorylation, and autophagy-initiating molecules and increase in mTOR phosphorylation. In conclusion, these results suggest the involvement of ROS, SESN2, AMPK, and mTOR in the CS-induced autophagic process in the lung.