Aging exacerbates muscle function, power, strength, and endurance; it also increases the incidence of falls and chronic metabolic diseases, which impact the quality of life. The reduction of muscle function in older adults is predominantly because of the decrease in muscle mass during aging, a process known as sarcopenia. 1) As aging progresses, skeletal muscles show decreased responsiveness to physical activity and other anabolic stimuli, resulting in a decrease in the muscle protein synthetic response referred to as anabolic resistance. 2) Background: This study explored the effects of aging on the expression of angiogenic and muscle protein synthesis factors, as well as the number of satellite cells affecting sarcopenia in naturally aged rat skeletal muscles. Methods: We divided 16 Sprague-Dawley rats into young (12 weeks old, n=8) and old (24 months old, n=8) groups and compared muscle and body weight (BW) between them. We also analyzed the expression levels of angiogenic and muscle growth proteins in soleus (slow-twitch) and extensor digitorum longus (EDL; fast-twitch) muscles by western blotting and assessed the number of skeletal muscle satellite cells and myonuclei and mean fiber cross-sectional area (CSA) using by immunofluorescence staining. Results: EDL/BW was significantly lower in old rats than in young rats (p=0.002). The vascular endothelial growth factor level in soleus muscles was significantly lower in old rats than in young rats (p=0.001). Hypoxia-inducible factor 1-alpha and fetal liver kinase 1 levels in EDL muscles were lower in old rats than in young rats (p=0.001). The mammalian target of rapamycin (mTOR), p70S6K, and 4E-BP1 levels were significantly lower in the soleus muscles of old rats than in those of young rats (p<0.01). Similarly, insulin growth factor-1, Akt, mTOR, and p70S6K levels were significantly lower in EDL muscles of old rats than in those of young rats (p<0.01). Additionally, myonuclei/fiber, Pax7/fiber, and mean fiber CSAs in both muscle types were significantly lower in old rats than in young rats (p<0.01). Conclusion: These data suggest different regulation of indices of angiogenic and muscle growth with aging in different muscle types.

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Arabinoxylan (Ara) rice bran has been shown to be a potent biological response modifier as manifested by stimulation of different arms of the immune system. We examined the effects of Ara rice bran and exercise on the immune function and cytokines in lipopolysaccharide (LPS)-stimulated rats. As the results, tumor necrosis factor-α as representative inflammatory cytokines showed a significantly lower in Ara supplement group, thus the Ara rice bran had a higher inhibitory activity than the both exercise and control group. However, 4 weeks of exercise training significantly increased inflammatory reactions rather than treatment with Ara in LPS-treated rats. The Ara rice bran acted to decrease the inflammatory reaction. These results suggest that the supplement of Ara rice bran is likely contribute to inflammation response and the Ara rice bran can be used as a possible safe alternative to the immunotherapeutic modalities.

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