Efeitos do extrato da <i>Euterpe oleracea</i> Mart. (Açaí) sobre o treinamento físico aeróbico de ratos

Abstract

The chronic exercise training results in adaptation of skeletal muscle to the increased metabolic demand. Adjustments in vascular control mechanisms plays an important role in increasing blood flow to the muscle during and after exercise. On the other hand, the increase in reactive oxygen species may occur as a result of increased oxygen uptake. Previous studies from our group demonstrated that the hydroalcoholic extract from the seeds of açaí (ASE) has antioxidant and vasodilator properties. Thus, the aim of this study was to evaluate if treatment with ASE, rich in polyphenols improves chronic exercise training. Wistar rats were divided in four groups: Sedentary (standard diet), Sedentary+ASE (standard diet + ASE 200mg/kg), Training (standard diet and, subjected to exercise training) and Training+ASE (standard diet + ASE 200 mg/kg subjected to exercise training). The test consisted of an exercise protocol on a treadmill, with initial speed of 3 m/min, increased to 4m/min every three minutes until exhaustion of the animal, at which no longer maintains the racing standard. The animals trained for 4 weeks, 5 times per week with duration of 30 minutes per session. The training intensity was 60% of the maximum speed reached during maximal incremental test. Blood glucose and lactate were measured in plasma by glucose and lactate meter, the vascular reactivity was studied in perfused mesenteric arterial bed (MAB). Oxidative damage, and antioxidant enzymatic activity were measured in muscle skeletal tissue homogenates and plasma. Western blotting was evaluated in in muscle skeletal tissue homogenates. The distance (m) and exercise time (min) were significantly increased in the Trainings in relation to the training group. The lactate levels were reduced in Training + ASE ASE. The glucose levels were not different between groups. The vascular reactivity to small doses of NOR was reduced in relation to Sedentay group and the vasodilator effect of ACh was increase in training groups. The malondialdehyde level did not change between groups as well as the carbonylation of proteins. The activity of the enzyme superoxide dismutase was significantly higher in the Training + ASE group compared to the Training and Sedentary groups in muscle tissue and the GPx was significant higher in the supplemented groups with ASE compared to the control groups in plasma. The protein expression of PGC1α was higher in the Training group compared to the sedentary groups. Therefore, ASE increased the distance and exercise time in rats subjected to exercise training, suggesting an important beneficial effect of the extract on the performance of this animals. The reduction of vascular resistance and the increased antioxidant capacity may probably promote better oxygenation of the muscle, reducing the production of lactate and muscle fatigue.