Novel effects of reverse transcriptase inhibitor supplementation in skeletal muscle of old mice.

Aging is the primary risk factor for the development of many chronic diseases, including dementia, cardiovascular disease, and diabetes. There is significant interest in identifying novel "geroprotective" agents, including by repurposing existing drugs, but such treatments may affect organ systems differently. One current example is the nucleoside reverse transcriptase inhibitor 3TC, which has been increasingly studied as a potential gerotherapeutic. Recent data suggest 3TC may reduce inflammation and improve cognitive function in older mice; however, the effects of 3TC on other tissues in aged animals are less well characterized. Here, we use transcriptomics (RNA-seq) and targeted metabolomics to investigate the influence of 3TC supplementation on skeletal muscle in older mice. We show that 3TC: (a) does not overtly affect muscle mass or functional/health markers; (b) largely reverses age-related changes in gene expression and metabolite signatures; and (c) is potentially beneficial for mitochondrial function in old animals via increases in antioxidant enzymes and decreases in mitochondrial reactive oxygen species. Collectively, our results suggest that, in addition to its protective effects in other tissues, 3TC supplementation does not have adverse effects in aged muscle, and may even protect muscle/mitochondrial health in this context.