MYH6 and sarcopenia: To address whether ghrelin levels during aging affect sarcopenia development, we examined young (3-month-old), adult (6-month-old), middle-aged (12-month-old), and old (24-month-old) Myh6/Ghrl transgenic mice characterized by high levels of circulating UnAG, up to 100 times more than WT animals (Tg; [7, 13]), their WT littermates, and ghrelin knockout (Ghrl KO; [22]) mice, lacking all the gene-derived peptides.