ABSTRACT
The purpose of this study was to examine the effects of combination of a heat stress and astaxanthin supplementation, known as a potent anti-oxidative nutrient, on muscle protein degradation and disuse muscle atrophy. Fifty-two male Wistar rats (261.7±1.17 g) were divided into five groups: control (Cont, n=10), suspension (Sus, n=11), heat stress and suspension (Heat, n=10), astaxanthin and suspension (Ax, n=10), and heat stress, astaxanthin and suspension (H+A, n=11). There were no significant differences in Cu,Zn-SOD, cathepsin L and caspase-3 levels among the Heat, Ax and H+A groups in the soleus and plantaris muscles. Although levels of calpain 2 and ubiquitinated protein in the myofibrillar fraction in the soleus muscle were not significantly different among the Heat, Ax and H+A groups, levels in the H+A group were significantly (p<0.05) lower than Sus. Concerning atrophied plantaris muscles, the H+A group significantly (p<0.05) suppressed the expression of calpain 1 in the myofibrillar fraction, but there were no marked changes of proteolytic indexes. These data indicate that the combination of the heat stress and astaxanthin supplementation could be effective in inhibiting muscle protein degradation in disuse atrophy of the soleus.
ABSTRACT
Oxidative stress is thought to be a significant contributing factor of age-related sarcopenia. We tested the hypothesis that long-term dietary antioxidant (astaxanthin) intake attenuates sarcopenia. Wistar strain male rats, aged 45 weeks old, were given either control (Cont) or astaxanthin feed (0.004%, Ax) for 1 year. The soleus muscle weight and muscle weight-to-body weight ratios in Ax group were significantly higher than in Cont group, but tibialis anterior muscle mass was similar between the two dietary groups. The level of ubiquitinated proteins was significantly lower in the soleus muscles of Ax group, but not in tibialis anterior muscles when compared with Cont group. Tibialis anterior levels of cathepsin L, especially, and caspase-3 tended to be lower in Ax group than in Cont group. Cathepsin L levels were significantly lower. Whereas no differences between Cont and Ax were observed in soleus levels. There were no significant differences in Ax supplementation on calpain 1 and 2, UBC3B, Cu/Zn SOD and nitrotyrosine levels in either soleus or tibialis anterior muscles. Our data suggest that long-term dietary astaxanthin intake attenuates age-related muscle atrophy, due in part, to reduction in ubiquitination of myofibrillar protein in slow soleus muscles, but not in fast tibialis anterior muscles.