Effect of voluntary exercise on 3'-methyl-4-dimethylaminoazobenzene-induced hepatomas in male Jc1:Wistar rats.

The effect of voluntary exercise on 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB)-induced hepatomas was investigated in male Jc1:Wistar rats. Beginning at 10 weeks of age, animals were divided into two groups (sedentary and exercise) and housed in individual cages. Food intake and wheel exercise were automatically controlled in the cages of the exercise group. Body weights were monitored throughout the study. Food availability was controlled in order to equate length and weight gain. From 27 weeks to termination of the study at 62 weeks, all animals were administered 3'-Me-DAB in the diet at a dose level of 0.0177 g/day/kg body wt. All animals were sacrificed at 62 weeks of age. The incidence of hepatomas was significantly lower in the exercise group as compared with the sedentary group (0% and 65%, respectively). Liver weight was significantly greater in the exercise group compared with sedentary animals without hepatomas. The weight of epididymal fat pads was significantly lower in the exercise group. Serum alkaline phosphate was significantly higher in the exercise group as compared with the sedentary group. Serum gamma-glutamyl-transpeptidase levels were higher in the sedentary group than in the exercise group. In addition, gamma-glutamyl-transpeptidase levels were significantly higher in sedentary animals with hepatomas than in sedentary animals without hepatomas. These results demonstrate that voluntary exercise decreases 3'-Me-DAB-induced hepatomas and that this decrease is associated with an increase in serum alkaline phosphatase and a decrease in serum gamma-glutamyl-transpeptidase levels.