Sarcopenia of aging: underlying cellular mechanisms and protection by calorie restriction.
Sarcopenia, the loss of muscle mass and function, is a common feature of aging and impacts on individual health and quality of life. Several cellular mechanisms have been involved in the pathogenesis of this syndrome, including mitochondrial dysfunction, altered apoptotic and autophagic signaling, and, more recently, trace metal dyshomeostasis. Calorie restriction (CR) without malnutrition has been shown to ameliorate the age-related loss of muscle mass in a variety a species. Mechanisms of protection span from preservation of mitochondrial functional and structural integrity to mitochondrial biogenesis, reduction of oxidative stress, and favorable modulation of apoptotic and autophagic signaling pathways. Importantly, preliminary evidence indicates that moderate CR may promote muscle mitochondrial biogenesis in middle-aged human subjects. Further research is warranted to investigate whether CR may represent a safe and efficient strategy to delay the onset and mitigate the progression of sarcopenia in older adults. (c) 2009 International Union of Biochemistry and Molecular Biology, Inc.