Effects of forced and spontaneous exercise on 8-hydroxydeoxyguanosine levels in rat organs.

We investigated the effects of forced and spontaneous exercise on the levels of 8-hydroxydeoxyguanosine (8-OH-dG), a form of oxidative DNA damage, in rat organs (heart, lung, and liver). Rats were randomly assigned to one of three groups: forced exercise group (F), spontaneous exercise group (S), and sedentary control group (C). The mean levels of 8-OH-dG in the F group were 1.9-, 2.1-, and 2.4-fold higher in the heart, lung, and liver DNA, respectively, than in the S group. In the S group of rats, the distance run was not significantly correlated to the 8-OH-dG levels in the heart, lung, and liver DNA. These results demonstrate that the intensity of exercise is an important determinant in DNA damage, and suggest that spontaneous physical exercise is beneficial for maintaining a low level of oxidative DNA damage.