Morphometric changes induced by amino acid supplementation in skeletal and cardiac muscles of old mice

Aging is associated with progressive structural disorganization of muscular and cardiac fibers, decreasing functional capacity and increased disease and death. Aging is also characterized by disturbances in protein synthesis with impaired cellular organelles functions, in particular the mitochondria. The availability of amino acids is a key factor for the overall metabolism of mammals and exogenous supplements of amino acid mixtures (AAm) could be a valid therapeutic strategy to improve quality of life avoiding malnutrition and muscle wasting in the elder. We therefore investigated the morpho-quantitative effects of long-term AAm supplementation on the mitochondria and sarcomere (by electron microscope) and on collagen matrix deposition (by hystological techniques) in both skeletal and cardiac muscles of young and aged mice. Our data showed that old animals had less mitochondria and massive fibrosis in both muscles. Long term AAm: a) increased the number and volume of mitochondria and sarcomere volume and b) decreased fibrosis in both skeletal muscle and hearts in old rats. These findings indicate that AAm restored muscular morphological parameters and probably improve the mechanical performances of these organs. These results could be interesting from a clinical point of view. Indeed, AAm supplementation could play a role in the prevention and/or treatment of senile sarcopenia and cardiac dysfunction.