Objective: Exercise markedly increases oxygen uptake by active muscles and consequently increases generation of reactive oxygen species. A dietary deficiency in selenium (Se) can increase the sensitivity of the living system to oxidative stress. delta-Aminolevulinate dehydratase (delta-ALA-D), succinate dehydrogenase (SDH), and lactate dehydrogenase (LDH) are sulfhydryl-containing enzymes, and their activities are sensitive to the presence of oxidizing agents. We investigated the effect of Se deficiency and supplementation on delta-ALA-D, SDH, and LDH activities in mice subjected to swim training for 8 wk.
Methods: Three-month-old female mice were randomly assigned and fed a basal diet, a basal diet plus 1 ppm of Se, and a basal diet plus 40 ppm of Se. These groups were further divided into sedentary and swim-trained groups. A mass equivalent of 5% of the animal's body weight was fixed to the tail. Animals were then exercised for 60 min/d, 4 d/wk.
Results: Swim-training associated with Se-deficient diet diminished delta-ALA-D activity in the livers and kidneys. SDH activity was diminished in the skeletal and cardiac muscles of this group.
Conclusions: These results indicated that exercise associated with dietary Se deficiency can inhibit the production of thiol-containing enzymes, delta-ALA-D and SDH, from different tissues; however, LDH activity was not changed. The decrease in enzyme activities can be tentatively attributed to oxidation of thiol groups by the reactive oxygen species produced by exercise.