The histone deacetylase inhibitor butyrate improves metabolism and reduces muscle atrophy during aging

Sarcopenia, the loss of skeletal muscle mass and function during aging, is a major contributor to disability and frailty in the elderly. Previous studies found a protective effect of reduced histone deacetylase activity in models of neurogenic muscle atrophy. Because loss of muscle mass during aging is associated with loss of motor neuron innervation, we investigated the potential for the histone deacetylase (HDAC) inhibitor butyrate to modulate agerelated muscle loss. Consistent with previous studies, we found significant loss of hindlimb muscle mass in 26-month-old C57BI/6 female mice fed a control diet. Butyrate treatment starting at 16 months of age wholly or partially protected against muscle atrophy in hindlimb muscles. Butyrate increased muscle fiber crosssectional area and prevented intramuscular fat accumulation in the old mice. In addition to the protective effect on muscle mass, butyrate reduced fat mass and improved glucose metabolism in 26-month-old mice as determined by a glucose tolerance test. Furthermore, butyrate increased markers of mitochondrial biogenesis in skeletal muscle and whole-body oxygen consumption without affecting activity. The increase in mass in butyratetreated mice was not due to reduced ubiquitin-mediated proteasomal degradation. However, butyrate reduced markers of oxidative stress and apoptosis and altered antioxidant enzyme activity. Our data is the first to show a beneficial effect of butyrate on muscle mass during aging and suggests HDACs contribute to age-related muscle atrophy and may be effective targets for intervention in sarcopenia and age-related metabolic disease.