We examined the effect of a combination of astaxanthin (AX) supplementation, repeated heat stress, and intermittent reloading (IR) on satellite cells in unloaded rat soleus muscles. Forty-nine male Wistar rats (8-week-old) were divided into control, hind-limb unweighting (HU), IR during HU, IR with AX supplementation, IR with repeated heat stress (41.0-41.5 °C for 30 min), and IR with AX supplementation and repeated heat stress groups. After the experimental period, the antigravitational soleus muscle was analyzed using an immunohistochemical technique. Our results revealed that the combination of dietary AX supplementation and heat stress resulted in protection against disuse muscle atrophy in the soleus muscle. This protective effect may be partially due to a higher satellite cell number in the atrophied soleus muscle in the IR/AX/heat stress group compared with the numbers found in the other groups. We concluded that the combination treatment with dietary AX supplementation and repeated heat stress attenuates soleus muscle atrophy, in part by increasing the number of satellite cells.
Animals ; Body Weight ; Dietary Supplements ; Fibrinolytic Agents/pharmacology* ; Heat-Shock Response ; Hindlimb ; Hot Temperature ; Immunohistochemistry ; Male ; Muscle, Skeletal ; Muscular Atrophy/drug therapy* ; Oxidative Stress ; Rats ; Rats, Wistar ; Satellite Cells, Skeletal Muscle/cytology* ; Xanthophylls/pharmacology*

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.

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.

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.

It has been demonstrated that exercise induces heat shock proteins (HSPs) . However, no study has investigated changes in HSPs following endurance training at different speeds. Therefore, this study was designed to investigate the effect of treadmill training at different running speeds on induction HSPs. One group of male Wistar rats was assigned as a sedentary control, three groups were assigned for exercise training (10 m/min, 20 m/min and 30 m/min) and another three groups for one acute bout of exercise (10 m/min, 20 m/min and 30 m/min) . Each training group ran at each speed for 30 min/day, 5 days a week for 8 weeks. The acute exercise group performed the exercise only once. Forty-eight hours after the last exercise session was completed, the rats were sacrificed and the plantaris (PLA) and soleus (SOL) muscles were dissected. In the acute exercise group, the content of HSP72 in both the PLA and SQL increased (p<0.05) at all speeds, and the content of HSP60 increased significantly (p<0.05) at all speeds for the PLA, but not for the SOL. On the other hand, in the endurance group, the content of HSP72 and HSP60 in both muscles increased in 30 m/min groups. These results indicate that an increase in HSP72 and HSP60 by endurance training is induced by high intensity training in both muscles. This was not found to be the case with the acute exercise groups.

The circadian rhythm of heart rate is well known. The purpose of this study was to investigate the characteristics of the relation between heart rate and oxygen uptake during a graded exercise testing with and without previous exercise. Eight healthy male students, aged 18 to 21 years, performed the graded sub-maximal exercise two times using a treadmill, after walking on a treadmill at a speed of 60 m/min for a total of 4 hours (2 hours in the morning, 2 hours in the afternoon) and without previous prolonged walking. The apparent resting heart rate after one hour of walking in the afternoon (82.3±9.1 beats mm) was higher than in the morning (71.3±5.8 beats/min), and this phenomenon was observed continuously exercise heart rate at the end of 2 hours of walking (afternoon : 96.4±5.4, morning: 87.2±7.3 beats min) . On the other hand, the oxygen uptake during exercise did not alter at the end of walking (afternoon: 622±85, morning: 600±133 ml/min) . This walking intensity ranged from 17.1 to 26.6, with a mean of 20.5 percent of maximal oxygen uptake. The pre-exercise resting heart rate before the exercise testing altered from -4.8 to 13.1 beats/min with and without the presence of walking. The observed individual regression line between heart rate and oxygen uptake from the testing shifted along with the altered resting heart rate. Therefore, the calculated individual new regression lines with and without walking between net heart rate, excluding pre-exercise rest, and oxygen uptake were approximate to a constant line. It was concluded that the exercise energy expenditure could be calculated accurately (-2 to 7 % of errors) using net heart rate, as compared with overestimations of the actual energy cost using the higher resting heart rate.

The effects of testosterone on the structural and contractile properties of the denervated rat skeletal muscles that were not influenced by neurotrophic-effects were investigated. Male Wistar strain rats (3-week-old, n=28) were used in the present study. All rats were divided into four (n=7, for each) groups; control (C), testosterone control (TC), denervated (DN), and denervated with testosterone (DNT) groups. Sciatic nerves of DN and DNT groups' rats were resected at the 4-week-old after birth. Testosterone that was melted in corn-oil was administered (40 mg/kg body weight/week) for the TC and DNT groups. At the end of breeding period (15-week-old), soleus (SOL) and extensor digitorum longus (EDL) muscles were dissected from both hindlimbs and contractile profiles were analyzed in vitro. Relative weight (muscle weight/body weight) of SOL muscle in the DNT group was significantly (p<0.01) higher than that of the DN group. There is no significant difference in EDL muscle between the DN and DNT groups. Time to peak tension and half relaxation time in EDL muscle of the DNT group was significantly (p<0.05) higher than those of the DN group. Maximum twitch tension was prone to decrease following denervation, and significantly (p<0.01) difference between the DN and DNT groups in both muscles regarding the maximum twitch tension was observed. There is no significant difference of myosin and actomyosin ATPase activities comparison of each group in SOL muscle, however, the TC group were significantly higher than those of the C group in EDL muscle. These results suggested that the effects of testosterone for the hypertrophy in skeletal muscles were not synergistic effects with the neurotrophiceffects, however, for the ATPase in fast muscle act synergistically with the neurotrophic effect to change of myosin ATPase. Moreover, it was also suggested that the sensitivity to the testosterone was different in each type of fiber.

The effect of swimming training on creatine ki nase (CK) isoenzyme compositions (cytoplasmic CK : CK-MM, -MB, -BB ; mitochondrial CK : m-CK) of coleus (SOL), extensor digitorum longus (EDL) and heart muscles were studied. Wistar strain male rats were trained by swimming at a water temperature of 38±2°C, loaded with a weight equal to 5% of their body weight attached to their tails, and made to swim 4-days per week from the age of 4 weeks old for 4, 6 and 8 weeks. CK isoenzyme compositions of SOL, EDL and heart were different from those of other muscles. The activities of CK-MB and m-CK of SOL, EDL and heart increased following exercise training. CK isoenzyme composition of skeletal muscle (SOL and EDL) tended to qualitatively resemble the heart with training. These results suggest that the training-induced metabolic change in skeletal muscle causes similar CK isoenzyme composition to the heart muscle, and ensure energy production for the continuous muscle contraction during endurance exercise. The possibility that the source of the increased serum CK-MB activity after exercise is from the skeletal muscle should be examined thoroughly when the high serum CK-MB activity is interpreted.

The effects of different types of running trainings (sprint or endurance) on the glycolytic (lactate dehydrogenase : LDH, phosphofructokinase : PFK and pyruvate kinase : PK) and oxidative (succinate dehydrogenase : SDH and malate dehydrogenase : MDH) enzymes activities and on the mitochondrial contents in single muscle fiber of different types (slow-twitch oxidative : SO, fast-twitch oxidative glycolytic : FOG and fast-twitch glycolytic : FG) were studied employing biochemical and electron microscopic techniques. Male Wistar strain rats were trained by treadmill 5 days/week beginning the age of 3 weeks old for 16 weeks. Single muscle fibers were dissected from soleus and extensor digitorum longus muscles, and typed histochemically into SO, FOG and FG fibers. The remaining parts of the single muscle fiber were used for biochemical and electron microscopic analyses. Glycolytic enzymes activities were increased in FG and FOG fibers following sprint training. Oxidative enzymes activities were increased in all types of fiber following both trainings. Mitochondrial contents in single muscle fiber were increased in FOG fiber following sprint training and in SO fiber following endurance training. These results suggest that the increase of glycolytic enzymes activity following sprint training were depended on the the fast-type fiber specifically and that of oxidative enzymes activity were depended on all types of fiber in whole muscle. It seems that the increase of oxidative enzymes activity following exercise training alone was not only depended on the increase of mitochondrial contents in skeletal muscle fiber.

Fifty-two trained athletes (15 short-distance runners, 20 long-distance runners, and 17 jumpers) and 5 controls were examined for leg length discrepancy, pelvic obliquity, scoliosis, leg strength discrepancy, and leg injury. Forty-seven subjects (90%) in the trained group and 4 subjects (80%) in the control group had leg length discrepancies. Differences of the femur lengths and tibia lengths, not of the joint space or soft tissue, were main factors of leg length discrepancies. There were no significant differences in leg length discrepancy and in pelvic obliquity between the trained and control groups. The trained group had twice as many leg length discrepancies and pelvic obliquities as the control group in average. A positive correlation between leg length discrepancy and pelvic obliquity was noted (p<0.001) . Among the jumpers, those who had suffered from hamstring muscle strain showed significantly more discrepancies in the right and left knee flexion strengths than the jumpers who had never experienced such muscle strain (p<0.41) . The rate of knee flexion strength against extension strength was significantly lower in the jumpers who had experienced knee joint injuries (p<0.01) .
The results indicate that leg length discrepancy affects on the pelvic obliquity and scoliosis. Differences of the femur lengths and tibia lengths were main factors of length discrepancy. It is possible that an inequality of load on the right and left legs may cause leg length discrepancy.