Effect of exercise training on energy balance of orchidectomized rats

The purpose of the present study was to investigate both the respective and interactive roles of exercise training and testosterone on energy balance. Male rats were divided into sedentary and exercise-trained groups. Each group formed was further divided into a sham-operated group, an orchidectomized group, or an orchidectomized group treated with testosterone. Rats were exercised on a motor-driven treadmill for 1 h/day over 28 consecutive days, after which rats were killed. Energy balance measurements, body composition analyses, and serum testosterone assay were then performed. The weight, protein content, and cytochrome-c oxidase activity of interscapular brown adipose tissue (IBAT) were also measured. Results indicate that total food intake, final body weight, and body weight gain were generally lower in exercise-trained rats than in sedentary animals. In orchidectomized rats treated with testosterone, gains of both fat and protein were lower in exercise-trained than in sedentary animals. There was no difference in metabolizable energy intake and body energy gain between trained and sedentary rats that underwent orchidectomy without replacement therapy. In orchidectomized groups of rats, energy gain was lower in trained rats that were treated with testosterone than in those that did not receive any treatment. Furthermore, in trained orchidectomized rats treated with testosterone, both energetic efficiency and energy density of body weight gain were lower than those of trained orchidectomized rats that were not treated. Finally, a significant reduction in IBAT weight was observed in exercise-trained animals, whereas neither exercise nor the various hormonal manipulations affected IBAT protein content and cytochrome-c oxidase activity.(ABSTRACT TRUNCATED AT 250 WORDS)