ABSTRACT
Objective To observe the alterations of Sirt1 and mTOR activity in gastrocnemius muscles of mice with sarcopenia. Methods Aged (26 months old) and young (6 months old) male C57BL/6J mice (n=16,respective-ly) were randomly arranged into 2 groups respectively, i. e. middle-aged control ( MC) , middle-aged suspension ( MS) , aged control( AC) and aged suspension( AS) . Aged mice were hindlimb suspended for two weeks to estab-lish a sarcopenic model. Kits and Western blot were used to detecte related factors and protein expression of Sirt1 and mTOR pathway. Results 1) the content of NAD+and the ratio of NAD+/NADH: AC group was significantly lower than MC group ( P＜0.01 or P＜0.05) , HLS group was significantly less than the control group ( P＜0.01 or P＜0.05) . 2) Sirt1 expression: AC group was significantly higher than MC group ( P＜0.05) , and HLS group was significantly higher than that of the control group (P＜0.05).3)Sirt1 downstream substrates (PGC-1α, FOXO1 and P53), NAMPT protein expression and Sirt1 activity: AC group was significantly lower than MC group ( P＜0.05 or P＜0.05 or P＜0.01) , HLS group was significantly less than the control group ( P＜0.05 or P＜0.05 or P＜0.05) . 4) phosphorylation of mTOR, p70S6K and 4E-BP1: AC group was significantly higher than MC group ( P＜0.05) , HLS group was significantly less than the control group ( P＜0.05) . Conclusions Sirt1 and mTOR are involved in the pathogenesis of mice with sarcopenia.