Fig. 4: CR improves muscle function without suppressing mTORC1 activity in the TSCmKO model of accelerated muscle aging.
From: Distinct and additive effects of calorie restriction and rapamycin in aging skeletal muscle
A Experimental design schematic. B Body, C whole-body fat, and D lean mass for WT and TSCmKO mice fed ad libitum (WT-AL and TSC-AL) or 70% of ad libitum (WT-CR and TSC-CR) beginning at 3 months of age. E Whole-body metabolic analysis of energy expenditure normalized to body surface area and F respiratory exchange ratio (VCO2/VO2; lower) reported every 2 h across one full day (white)/night (black) cycle (left) and day and night-time averages (right) in the month prior to endpoint measures; n = 12 (10mCON), 9 (30mCON), and 10 (30mCR) mice. G Representative western blot analysis of mTORC1 pathway components in gastrocnemius (GAS) muscle. H Quantification of western blots showing the abundance of phosphorylated protein normalized to total protein for mTOR, S6 and 4EBP1. I Inverted grid hang time and J time spent on a rotating rod. Isolated muscle function parameters for SOL (upper panel) and EDL (lower panel), including K specific force, L peak tetanic force normalized to body mass, M twitch time-to-peak tension, and N half-relaxation time as well as (O) fatigue response to multiple stimulations. For B-D, n = 12, 8, 9 and 8 except for the final time point where n = 16, 13, 12, and 12 for WT-AL, WT-CR, TSC-AL and TSC-CR, respectively. For E, F, n = 4, 4, 3, and 3; for G-H, n = 9, 7, 8, and 7 (pS6S235/236 and p4EBP1S65), 5, 5, 4, and 5 (pmTORS2448) and 4, 4, 4, and 4 (pS6S240/244); for I, n = 12, 8, 9 and 8; for J, n = 7, 5, 5 and 5; for K, L, n = 15, 11, 12, 11 (EDL) and 11, 8, 9, 8 (SOL); for M, N, n = 14, 10, 11, 12 (EDL) and 10, 8, 7, 6 (SOL) and; for O, n = 12, 9, 8, 8 (EDL) and 8, 7, 6, 7 (SOL) for WT-AL, WT-CR, TSC-AL and TSC-CR, respectively. Data are mean ± SEM. Two-way ANOVAs with Tukey post hoc tests were used to compare the data. *, **, and *** denote a significant difference between groups of P < 0.05, P < 0.01, and P < 0.001, respectively. #Denotes a trend where 0.05 < P < 0.10. Colored asterisks refer to the group of comparison. Experimental scheme in A created with BioRender.com.
