Abstract 15157: Swimming Reduces the Severity of Atherosclerosis by Antioxidant Effects in Apolipoprotein E-Deficient Mice

Abstract

BACKGROUND: Aerobic exercise training may protect against the development of atherosclerosis. However, the precise mechanisms are still unknown. PURPOSE: We assessed the hypothesis that exercise training reduced the severity of experimental atherosclerosis in apolipoprotein (apo) E-deficient mice by antioxidant effects.

METHODS: Exercise training (45 min swimming, 3 times per week) was conducted on apo E-deficient mice fed a high fat diet. Over 8 and 16 weeks on alternate days, mice were treated with and without exercise, and exercise-treated additional mice were orally given by 25 mg/kg/day of NG-nitro-L-arginine methylester (L-NAME), an inhibitor of nitric oxide synthase. In addition, the effect of L-arginine (2.25%, orally) against L-NAME was also tested (each group, n=6∼11).

RESULTS: Fatty streak formation and fibrofatty plaques developed in apo E-deficient mice fed a high fat diet, and were suppressed in mice treated with swimming for 8 and 16 weeks. Atherosclerotic lesions were not ameliorated in mice treated with exercise training associated with oral L-NAME. However, in mice treated with swimming associated with L-NAME and L-arginine, the lesions were reduced. The severity of atherosclerotic lesions was correlated with the expression of an endogenous antioxidant protein, thioredoxin. Namely, the expression of thioredoxin in mice treated with exercise was suppressed compared with mice without exercise. Plasma thiobarbituric acid-reactive substance levels were significantly lower in groups with exercise than in those without exercise or with exercise associated with L-NAME administration, suggesting the exercise-induced less lipid peroxidation. Differences in lesion area did not correlate with any significant alterations in serum lipid levels. The exercise load used in the current study did not affect myocardial energy metabolism efficacies, which was shown by the shift of myosin isozyme.

CONCLUSIONS: Exercise training suppressed atherosclerosis by antioxidant effects via vascular nitric oxide system.