DIETARY RESTRICTION ATTENUATES AGE-RELATED INCREASES IN RAT SKELETAL-MUSCLE ANTIOXIDANT ENZYME-ACTIVITIES

Dietary restriction (DR) retards aging in rodents, but its mechanism o f action remains unclear. Free radicals have been hypothesized to be i nvolved in aging and in DR's actions. We investigated the influences o f age and DR on the antioxidant enzymes catalase (CAT), glutathione pe roxidase (GPX), and superoxide dismutase (SOD) in skeletal muscle from 11-, 26- and 34-mo-old (BN x Fischer 344) F-1 rats fed either ad libi tum (AL) or subjected to a 30% DR from 14 weeks of age. The mass of th e upper hindlimb muscles recoverable in 34-mo-old AL rats was only 52% that of Ii-mo-old AL rats, whereas rats on DR showed a stable, interm ediate value at both ages. CAT and GPX activities increased progressiv ely and markedly in muscle of AL animals with aging. The increase in C AT activity,was partially attenuated by DR, while that of GPX was enti rely prevented. These effects of aging and DR were more profound in 12 ,000 x g pellets than in cytosolic fractions. SOD activities were more variable and not clearly influenced by age or DR, These data agree wi th prior reports of an age-related increase in skeletal muscle antioxi dant enzyme activities. Further, DR attenuates this alteration and doe s so most profoundly in the 12,000 x g pellet, the fraction which is e nriched in mitochondria.