Iron injections in mice increase skeletal muscle iron content, induce oxidative stress and reduce exercise performance

Abstract

Iron accelerates the production of reactive oxygen species (ROS). Excessive levels of ROS are thought to accelerate skeletal muscle fatigue and contribute to the loss of skeletal muscle mass and function with age. Patients with an iron overload disease frequently report symptoms of weakness and fatigue, which is attributed to reduced cardiac function. The contribution of skeletal muscle to these symptoms is unknown. Using a mouse model of iron overload, we determined the extent of iron accumulation in skeletal muscle and the concentrations of the iron storage protein ferritin. The level of oxidative stress, changes in antioxidant enzymes and exercise performance were also assessed. Compared with control mice, the iron overloaded mice had elevated levels of iron in the tibialis anterior muscle and a fourfold increase in ferritin light chain. The oxidative stress product malondialdehyde was increased in the iron group compared with the control group, as was the antioxidant enzyme activity of glutathione reductase and glutathione peroxidase. The iron group performed less work on an endurance test and produced less force in a strength test. Body weight and skeletal muscle weight were lower in the iron group following the intervention. Iron loading reduced the weight of the fast-twitch extensor digitorum longus muscle more than the slow-twitch soleus muscle. In summary, iron accumulation in skeletal muscle may play a significant role in the reduced exercise capacity seen in iron overload disorders and in ageing, and may play an underlying role in skeletal muscle atrophy.

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“…The highest muscle concentration occurred at 8 hours, 0.12 ± 0.02 mg Fe/cc, giving a peak tumor to peak non-tumor (surrounding muscle) ratio of 15.8. At 24 hours, the muscle content could not be distinguished from normal muscle iron content (0.068 mg Fe/cc 66 ), which would give a tumor to non-tumor ratio of .16.0 at 24 hours. Blood clearance exhibited a rapid early half-life of 2.0 hours followed by a slow component half-life of 14.0 hours.…”

EVALUATION OF THAI STYLE STRETCHING EXERCISE ON €œRUESI DUD TON” ON PHYSICAL HEALTH AND OXIDATIVE STRESS IN HEALTHY VOLUNTEER

“…It has been reported that the elevation of oxidative stress was associated with the decreased functional capacity of muscle (Stefania et al, 2004) which also includes the decreased muscle endurance and muscle strength (Reardon and Allen, 2009). …”

Iron restriction increases myoglobin gene and protein expression in Soleus muscle of rats

“…Studies performed in iron-treated mice showed an accumulation of this ion in soleus and EDL skeletal muscles, mainly in the ferritin light chain, which stocks iron; they also observed an increase of oxidative stress and antioxidant enzymes activity in these muscles (Reardon and Allen 2009). Rodriguez et al (2007) using microarray test, in which 47,000 probes were studied, have found that a small number of genes is altered in skeletal and cardiac muscle after iron overload, only those that, in some way, are involved in the metabolism of glucose and lipids.…”