Grant: Travel Awards - Institute Community Support

Sarcopenia is the decrease of muscle mass and strength that occurs with aging, and is believed to be a major cause of disability in the elderly. At advanced ages, skeletal muscle shows marked accumulation of denervated muscle cells, leading to an increased muscle atrophy and weakness. This dysfunction is the main cause of loss of independence and declining of quality of life in the elderly. As muscle undergoes repeated cycles of denervation (muscle cell disconnects from nerve) and reinnervation (subsequent reconnection) throughout adulthood, we hypothesized that the accumulation of denervated myofibers in advanced age is due to failure of signals in the muscle that promote reinnervation. To study this problem we examined muscle from a mouse model that has been genetically modified to exhibit greater susceptibility of the muscle fibers to become disconnected from the nerve and compared this to results in normally aged rat muscle. Our results indicated that aged rat muscle was more susceptible to becoming disconnected from their nerve than our mouse model and exhibited much larger changes in muscle signals related to this process. Furthermore, in aged rat muscle there was no change in signals that are necessary for reconnecting the muscle to its nerve. As such, our results suggest future treatments for aging muscle should address the factors responsible for successful reconnection of muscle fibers to nerves.