In this study, we analyzed the effect of aerobic exercise training (AET) and of a single bout of exercise on plasma oxidative stress and on antioxidant defenses in type 2 diabetes mellitus (DM) and in healthy control subjects (C). DM and C did not differ regarding triglycerides, high-density lipoprotein cholesterol (HDL-c), insulin, and HOMA index at baseline and after AET. To measure the lag time for low-density lipoprotein (LDL) oxidation (LAG) and the maximal rate of conjugated diene formation (MCD), participants' plasma HDL(2) and HDL(3) were incubated with LDL from pooled healthy donors' plasma. In the presence of HDL(3), both LAG and MCD were similar in C and DM, but only in DM did AET improve LAG and reduce MCD. In the presence of HDL(2), the lower baseline LAG in DM equaled C after AET. MCD was unchanged in DM after AET, but was lower than C only after AET. Furthermore, after AET plasma thiobarbituric acid-reactive substances were reduced only in DM subjects. Despite not modifying the total plasma antioxidant status and serum paraoxonase-1 activity in both groups, AET lowered the plasma lipid peroxides, corrected the HDL(2), and improved the HDL(3) antioxidant efficiency in DM independent of the changes in blood glucose, insulin, and plasma HDL concentration and composition.
Our results show that aerobic exercise training in diabetes mellitus improves the HDL efficiency against LDL oxidation and favors HDL maturation. These findings were independent of changes in insulin resistance and of the rise of plasma HDL cholesterol concentration.
RESUMOHá alguns relatos na literatura sugerindo associação entre polimorfismos do receptor b 2 -adrenérgico com obesidade e outros com hipertensão arterial. O objetivo do nosso estudo foi estudar a freqüência de um polimorfismo do receptor b 2 adrenérgico (Gln27Glu) em pacientes obesos (BMI 48 ± 8,2kg/m 2 ) e relacioná-lo com hipertensão arterial, e níveis de triglicérides, colesterol, insulina e glicose no sangue. Encontramos associação deste polimorfismo em obesos com hipertensão arterial. The sympathetic nervous system activation stimulates energy mobilization and utilization in the adipose tissue that is a favored target for high-energy substrate storage, mobilization and utilization. Adrenergic responsiveness may be altered in obesity and could be an important factor in the pathogenesis and maintenance of obesity state. In the hypertensive state there is physiological and biochemical evidence that b-adrenergic responsiveness is diminished in the face of increased sympathetic tone. Recently, several different polymorphic forms of the human b 2 AR have been identified in general population, including N-terminal substitutions of glutamine (Gln) for glutamic acid (Glu) at position 27. The aim of this study was to investigate the potential interaction between the b 2 AR (Gln27Glu) polymorphism and obesity accumulation and hypertension in morbidly obese subjects. The Ita I genotypes of b 2 AR were established using RFLP methods in 135 individuals with BMI 48 ± 8.02kg/m 2 . The frequency of Gln/Glu was 31.9% and in the homozygous Glu/Glu was 12.6%. No association was found between BMI, weight gain during the past years and the Ita I genotypes and neither was associated with levels of triglycerides, cholesterol, insulin and glucose. Positive association was found between blood pressure (systolic and diastolic) and presence of polymorphism. The results indicate at the first time that presence of polymorphism 27Glu may provide a mechanism for enhanced vascular reactivity and identify a candidate gene for hypertension in this obesity group. Na última década, a comunidade científica tem procurado estabelecer o papel da genética na etiologia da obesidade humana e de outras doenças complexas que têm componentes ambientais, comportamentais e genéticos. Estuda-se em que extensão os genes herdados têm influência no
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