Fig 1.
Effects of NYT on body weight, appetite, physical function, fatigue, and gastrocnemius muscle in SAMR1.
Body weight at 7 months of age (A), average daily food intake (B), rotarod test results (C), grip strength results (D), treadmill fatigue test results (E), percentage increase in resting time in the open field test (F), blood corticosterone concentration (G), and gastrocnemius weight-to-weight ratio (H). Cross-sectional area of Type 1 fibers (I), cross-sectional area of Type 2 fibers (J), and representative fluorescent stained images (green: Type 1 fibers, red: Type 2)(K). Feeding NYT to SAMR1 mice had no significant effects on body weight, food intake, physical function, fatigue, or the gastrocnemius muscle. “R1C,” SAMR1 mice fed the Control diet (n = 8); “R1N,” SAMR1 mice fed NYT (n = 8). Data are shown as mean ± standard error. Scale bar = 150 μm.
Fig 2.
Effect of NYT on age-related weight loss, anorexia, and motor function decline.
Weight at 6 and 7 months of age (A), percentage weight loss comparing mice at 6 and 7 months of age (B), average daily food intake (C), rotarod test results (D), and grip strength results (E). Aging significantly reduced body weight, motor function and grip strength; weight loss, anorexia, and motor function decline were significantly improved in the SAMP8 NYT group (“P8N,” n = 8) compared to those in the SAMP8 Control group (“P8C,” n = 8) (B-E). “R1C,” normal control SAMR1 (n = 8). Data are presented as mean ± standard error. *p<0.05, **p<0.01, ***p<0.001.
Fig 3.
Effect of NYT on age-related fatigue-like conditions.
The treadmill fatigue test (A), percentage increase in resting time in the open field test (B), and blood corticosterone concentration (C). The SAMP8 Control group (“P8C,” n = 8) exhibited a significantly faster time to fatigue and significantly increased time immobile in the open field test than that in the normal control, SAMR1 (“R1C,” n = 8). NYT intake significantly improved the time to fatigue and increased stationary time. Corticosterone was increased in both SAMP8 groups. Data are presented as mean ± standard error. *p<0.05, **p<0.01.
Fig 4.
Effect of NYT on weight and cross-sectional area of aged gastrocnemius muscle.
Gastrocnemius muscle weight-to-body weight ratio (A), cross-sectional area of Type 1 fibers (B), cross-sectional area of Type 2 fibers (C), and representative fluorescent stained images (green: Type 1 fibers, red: Type 2) (D). The SAMP8 Control group (“P8C,” n = 8) exhibited significantly reduced muscle weight and cross-sectional area compared to that in the normal control SAMR1 (“R1C,” n = 8) The SAMP8 NYT group (“P8N,” n = 8) exhibited heavier muscle weight and significantly larger Type 2 fibers than did the SAMP8 Control group. Data are presented as mean ± standard error. *p<0.05, **p<0.01, ***p<0.001; scale bar = 150 μm.
Fig 5.
Effect of NYT on age-related brain inflammation.
Representative images of Iba-1 immunoreactivity in brain tissue (A). The number of Iba-1 positive cells did not change significantly (B). Representative western blots and semi-quantitative analyses of the expressions of IL-1β, IL-1RA, and Iba-1 (C). IL-1β expression was significantly lower in the SAMP8 NYT group (“P8N”) than in the SAMP8 Control group (“P8C”) (D). IL-1RA expression was significantly higher in the SAMP8 NYT group than in the SAMP8 Control group (E). “R1C,” normal control SAMR1. No significant differences in the expression of Iba-1 protein were observed (F). Data are shown as mean ± standard error. *p<0.05, **p<0.01; scale bar = 50 μm (A), n = 4 per group for all data (B, D, E, F).
Fig 6.
Effect of NYT on inflammation in aged gastrocnemius muscle.
Co-stained images of F4/80 and DAPI in gastrocnemius muscle (A), The SAMP8 Control group (“P8C”) showed increased macrophages (B) Representative western blots and semi-quantitative analyses of the expressions of IL-1β and IL-1RA (C). The SAMP8 Control group (“P8C”) showed increased expression of IL-1β (D), and decreased expression of IL-1RA (E) compared to those in the normal control SAMR1 (“R1C”). Inflammation was significantly suppressed in the SAMP8 NYT group (“P8N”) compared to that in the SAMP8 Control group. Data are shown as mean ± standard error. *p<0.05, **p<0.01, ***p<0.001; scale bar = 50 μm (A). (A) and (C) were analyzed with n = 8 and n = 4 per group, respectively.