Abstract
The anthracycline antibiotic doxorubicin (DOX) has been shown to cause thymic involution and concurrent decreases in thymocyte (T‐cell) number. Acute exhaustive exercise has shown similar decrements in the thymus, with increases in lipid peroxide and decreased free‐radical protective enzymes; however, submaximal exercise has been shown to enhance viable T‐cell number. The purpose of this study was to examine the effects of endurance exercise training prior to DOX administration on thymus size, viable T‐cell number, and measures of oxidative stress. Ten week‐old Sprague‐Dawley rats were randomly assigned to an exercise group or a sedentary group for 10 weeks. After the activity treatment period, animals received DOX or saline as a control. Seventy‐two hours after injections, the thymus was excised, and T‐cells were isolated for cell count. Oxidative stress in thymic tissue was measured using a lipid peroxidation kit for measures of malondialdehyde (MDA). Exercise training attenuated the increased levels of MDA found in rat thymus following acute administration of DOX. The results suggest that endurance training may play a role in protecting the thymus from DOX‐induced damage.