Induction of oxidatively modified proteins in skeletal muscle by electrical stimulation and its suppression by dietary supplementation of (-)-epigallocatechin gallate.
The oxidative stress produced by electrical stimulation-induced muscle contraction was examined in the skeletal muscle proteins of rats that had been fed on the dietary flavonoid, (-)-epigallocatechin gallate (EGCg). Electrical stimulation of the rat leg muscle every second day for a two-week period resulted in an increased (p < 0.05) muscle weight and accumulation of oxidatively induced modified proteins. Similar stimulation conducted every day for only one week had no effect on the muscle weight or protein oxidation, although the rate of protein degradation increased. Rats fed on a 20% casein diet supplemented with 0.1% EGCg for 2 weeks responded to the electrical stimulation of muscle contraction by reducing the increased muscle protein carbonyl content when compared to their counterparts fed on a control diet. There was no change in activity of antioxidative enzymes in muscle tissue of the EGCg-fed rats receiving electrical stimulation. The results of this study show that the antioxidative property of EGCg was effective for suppressing oxidative modification of the skeletal muscle protein induced by electrical stimulation. This finding demonstrates that EGCg has a beneficial effect in vivo on the free radical-mediated oxidative damage to muscle proteins.
Nagasawa
T
T
Department of Bioscience and Technology, Faculty of Agriculture, Iwate University, Morioka, Japan. tnaga@iwate-u.ac.jp
Hayashi
H
H
Fujimaki
N
N
Nishizawa
N
N
Kitts
D D
DD
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001835:Body Weight; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D019587:Dietary Supplements; D004558:Electric Stimulation; D016166:Free Radical Scavengers / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D005979:Glutathione Peroxidase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D018384:Oxidative Stress / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D000975:Antioxidants; D016166:Free Radical Scavengers; D009124:Muscle Proteins; D017392:Thiobarbituric Acid Reactive Substances; D002392:Catechin; C045651:epigallocatechin gallate; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005982:Glutathione Transferase