Efeito da arginina dietética na permeabilidade intestinal e translocação bacteriana induzidas por exercício físico prolongado no calor

Abstract

The aim of present study was to evaluate the possible protective role of the arginine in the reduction of the intestinal permeability and bacterial translocation (BT) in mice subjected to prolonged physical exercise in a warm ambient. Preliminary experiments were conducted to determine the changes in the core body temperature of mice induced by treadmill exercise. The exercises performed at 34°C induced higher increases of abdominal temperature (39.97 ± 0.11°C), compared to the exercises performed in the temperate environment (38.59 ± 0.07°C). It was alsoobserved that, in a warm ambient, the velocity of 8 m/min allowed for more prolonged exercise duration (60 min), differently from those performed at 10 m/min (42 ± 6 min). Considering these results, the 60 min-treadmill running at a velocity of 8 m/min was selected as the experimental model to produce hyperthermia in the subsequentexperiments. The mice were divided in three groups and treated for seven days: Control (C-NS) and Hyperthermia (H-NS), both treated with standard AIN-93G diet and Hyperthermia treated with AIN-93G diet supplemented with arginine 2% of the total caloric content (H-Arg). Then, the animals of the H-NS and H-Arg groups were subjected to physical exercise on a treadmill in a warm environment. The animals ofthe C-NS group were allowed to move freely at 24°C. To investigate the occurrence of intestinal permeability and BT, the animals received, by gavage, DTPA labeled with technetium-99m (99mTc-DTPA) or 99mTc-E. coli, respectively. The H-NS group presented higher intestinal permeability, when compared with C-NS and H-Arg groups.Similarly, the BT was higher in the blood and liver of the animals from this group (HNS), when compared to the other groups investigated. The supplementation with arginine during 7 days, pre-treatment period, reduced to physiological levels both the intestinal permeability and the BT to the blood and liver. Statistically higher concentrations of the sIgA were found in H-NS and H-Arg groups, compared to C-NS group. Histological analysis showed no significant change in the intestinal epithelium among animals of different groups investigated. The exercise in the heat (34°C) contributed to the increase of the intestinal permeability and bacterial translocation. Moreover, the supplementation with arginine, 2% of the total caloric content, reduced the intestinal permeability and BT to physiological levels.