Effects of exogenous ghrelin on muscle atrophy in elderly mice

Objective To investigate the effects of acylated ghrelin and des-acylated ghrelin on skeletal muscle atrophy in elderly mice. Methods Eighteen-month-old wild type(WT)mice and ghrelin-/- mice were selected to perform body composition analysis and wheel-running test under conditions of feeding versus fasting.The gene expressions of myogenic regulatory factors including muscle differentiation factor MyoD, myogenin, atrogin-1, muscle-specific RING finger protein 1(muRF-1), and insulin growth factor 1(IGF-1)in mice gastrocnemius muscle were detected by realtime polymerase chain reaction(PCR). Results The locomotor activity during the wheel-running test were significantly lower in elderly ghrelin-/- mice than in elderly WT mice(3 929±263 times/h vs.5359±601 times/h, t=4.87, P 0.05). After 48 h fasting, the decrements of body weight, fat and muscle weight were more in ghrelin-/- mice than in WT mice(P<0.05). In fasting old ghrelin-/- mice, the gene expressions of MyoD and myogenin were increased(improved)(t=232.00 and 121.00, P<0.05), and the gene expressions of atrogin-1 and muRF-1 were decreased(improved)(t=30.40 and 54.00, P<0.05)after treatment with both acylated ghrelin and desacylated ghrelin. Conclusions The acylated ghrelin and desacylated ghrelin may play protective roles in age-related muscle atrophy. Key words: Ghrelin; Muscular atrophy