RESUMO
Increased oxidative stress in vascular cells plays a key role in the development of endothelial dysfunction and atherosclerosis. Uncoupling protein 2 (UCP2) is an important regulator of intracellular reactive oxygen species (ROS) production. This study was undertaken to test the hypothesis that, UCP2 functions as an inhibitor of the atherosclerotic process in endothelial cells. Adenovirus-mediated UCP2 (Ad-UCP2) overexpression led to a significant increase in endothelial nitric oxide synthase (eNOS) and decrease in endothelin-1 mRNA expression in human aortic endothelial cells (HAECs). Moreover, UCP2 inhibited the increase in ROS production and NF-kappaB activation, and apoptosis of HAECs induced by lysophophatidylcholine (LPC) and linoleic acid. LPC and linoleic acid caused mitochondrial calcium accumulation and transient mitochondrial membrane hyperpolarization, which was followed by depolarization. UCP2 overexpression prevented these processes. In isolated rat aorta, Ad-UCP2 infection markedly improved impaired vascular relaxation induced by LPC. The data collectively suggest that UCP2, functions as a physiologic regulator of ROS generation in endothelial cells. Thus, measures to increase UCP2 expression in vascular endothelial cells may aid in preventing the development and progression of atherosclerosis in patients with metabolic syndrome.
Assuntos
Adenoviridae/genética , Apoptose , Arteriosclerose/prevenção & controle , Células Endoteliais/fisiologia , Proteínas de Membrana Transportadoras/fisiologia , Proteínas Mitocondriais/fisiologia , Cálcio/metabolismo , Caspases/metabolismo , Células Cultivadas , Transporte de Elétrons , Endotelina-1/genética , Transferência Genética Horizontal , Humanos , Canais Iônicos , Ácido Linoleico/farmacologia , Lisofosfatidilcolinas/farmacologia , Proteínas de Membrana Transportadoras/genética , Proteínas Mitocondriais/genética , NF-kappa B/metabolismo , Óxido Nítrico/análise , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase Tipo III , RNA Mensageiro/análise , Espécies Reativas de Oxigênio , Proteína Desacopladora 2RESUMO
AMP-activated protein kinase (AMPK) functions as a fuel sensor in the cell and is activated when cellular energy is depleted. Here we report that alpha-lipoic acid (alpha-LA), a cofactor of mitochondrial enzymes, decreases hypothalamic AMPK activity and causes profound weight loss in rodents by reducing food intake and enhancing energy expenditure. Activation of hypothalamic AMPK reverses the effects of alpha-LA on food intake and energy expenditure. Intracerebroventricular (i.c.v.) administration of glucose decreases hypothalamic AMPK activity, whereas inhibition of intracellular glucose utilization through the administration of 2-deoxyglucose increases hypothalamic AMPK activity and food intake. The 2-deoxyglucose-induced hyperphagia is reversed by inhibiting hypothalamic AMPK. Our findings indicate that hypothalamic AMPK is important in the central regulation of food intake and energy expenditure and that alpha-LA exerts anti-obesity effects by suppressing hypothalamic AMPK activity.
Assuntos
Fármacos Antiobesidade/farmacologia , Proteínas Quinases Dependentes de AMP Cíclico/antagonistas & inibidores , Hipotálamo/efeitos dos fármacos , Ácido Tióctico/farmacologia , Animais , Peso Corporal/efeitos dos fármacos , Proteínas Quinases Dependentes de AMP Cíclico/fisiologia , Ingestão de Alimentos/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Hipotálamo/enzimologia , Hipotálamo/fisiologia , Leptina/fisiologia , Camundongos , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , RatosRESUMO
This study investigated the effect of oleic acid on the expression levels of endothelin-1 (ET-1) and on the signaling pathways mediating it in human aortic endothelial cells (HAECs). ET-1 mRNA expression was significantly increased by oleic acid in a dose- and time-dependent manner. Elevation of ET-1 expression in response to oleic acid was inhibited by the protein kinase C (PKC) inhibitor, GF109203X, or the NF-kappa B inhibitor, pyrrolidine dithiocarbamate. In addition, both PKC and NF-kappa B activities were significantly increased by oleic acid. Immunoblot analysis revealed that conventional PKCs (PKC-alpha and -beta II isoforms) were significantly increased in the membranous fractions of HAECs treated with oleic acid. PKC inhibitor completely abolished oleic acid-induced NF-kappa B activation, suggesting that PKC activation is upstream of NF-kappa B activation in oleic acid-induced ET-1 expression. These data suggest that elevated plasma oleic acid levels observed in obese, insulin-resistant subjects result in endothelial dysfunction, at least in part, through an increase in ET-1 expression.