Effects of Exercise Training on the Severity and Composition of Atherosclerotic Plaque in apoE-Deficient Mice

<i>Aim:</i> To investigate the effects of exercise on atherosclerotic plaque composition, the concentration of matrix metalloproteinases (MMPs) in the atherosclerotic plaque and the systemic circulation. <i>Methods:</i> Ninety apolipoprotein E-deficient (apoE^–/–) mice (45 male) were randomized to the following groups (n = 15 each): control male/female; sedentary male/female; exercise male/female. Mice were kept on a 16-week high-fat diet. Subsequently, the control groups were sacrificed, while the rest of the animals were placed on a normal diet for 6 more weeks. During the latter period, the exercise groups were trained daily on treadmill. At the end of the study, mice were euthanized, and blood samples as well as aortic root specimens were obtained. <i>Results:</i> Compared to control and sedentary animals, exercise training reduced atherosclerotic plaques (–30%; p < 0.01) and increased elastin and collagen content in both genders (p < 0.05). Body weight or lipid profile did not change significantly. Decreased macrophages and MMP-9 as well as increased tissue inhibitor of metalloproteinases 1 (TIMP-1) levels were observed in the atherosclerotic plaques of the exercise-treated groups (p < 0.05). Plasma concentrations of MMP-9 decreased, while plasma TIMP-1 levels increased in the exercise compared to control and sedentary groups (p < 0.05). <i>Conclusions:</i> Exercise training had a favorable effect on the size and composition of the atherosclerotic plaque in apoE^–/– mice, associated with suppressed MMP activity.