ABSTRACT
<p>Although icing treatment has been well accepted as aftercare in sports fields, the detailed mechanisms of the treatment is not fully understood. In this study, we investigated the effect of icing treatment on the recovery process of rat plantaris muscles with artificially induced muscle damage. Sixty male Wistar rats (8-weeks-old) were randomly assigned to three groups; control (CTL), bupivacaine-injected (BPVC), and icing treatment after BPVC (ICE). Icing treatment was applied for 20 min immediately after BPVC, and the treatment was used once per day for 3 days. The plantaris muscles were removed at 3, 7, 15, and 28 days after the muscle damage, then immunohistochemical and real time RT-PCR analysis were performed. In histochemical analysis, although significant changes were found in the relative muscle weight, cross-sectional area of muscle fiber, percentage of muscle fiber with central nuclei, and expressed immature myosin heavy chain isoforms after muscle damage, as compared to the CTL group, no differences were found between BPVC and ICE groups. In mRNA expression analysis, the ICE group had a significantly lower value of MyoD than the BPVC group at 3 days after the damage. Expression of IL-6 mRNA, which relates to muscle inflammation, indicated significantly higher value in BPVC, but not in ICE, than CTL groups at 7days after the damage. Furthermore, BKB<sub>2</sub> receptor, which relates to acute muscle soreness, indicated a significantly higher expression in BPVC than ICE groups at 3 days after the damage. These results suggest that icing treatment is effective to suppress muscle inflammation and soreness at an early stage of recovery from damage, but not effective for muscle regeneration at a later stage.</p>
ABSTRACT
In the present study, we investigated the effect of heat stress on disuse atrophy from changes in the muscle protein levels of desmin and calpain. Wistar strain female rats (6-8 months old) were randomly assigned to two experimental groups: control (C) and heat stress (H). One hindlimb of all animals was immobilized in plantar flexion with plaster. Before immobilization, animals in H group were placed in a heat chamber (42°C for 60 min). Following 6 days of immobilization, the soleus muscles were removed and analyzed. Although immobilization resulted in significant muscle atrophy in all experimental animals, the soleus weight-to-body weight ratio in immobilized limbs of H group was significantly higher compared to that of C group. Expression of desmin and HSP72 in the atrophied soleus muscle from C group was significantly lower compared with the contralateral muscle; but this was not the case in H group. Further, in C group, the ratio of autolyzed calpains I increased significantly in the atrophied muscle compared to the contralateral muscle. These results show that the effect of heat stress on disuse skeletal muscle atrophy is attributed to the decreasing degradation of desmin by suppressing the activation of calpain.
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.