A relative high dose of vitamin E does not attenuate unweighting-induced oxidative stress and ubiquitination in rat skeletal muscle.
We previously reported that intragastric administration of cysteine could be beneficial to prevent unweighting-induced ubiquitination and degradation of muscle protein in association with redox regulation [Ikemoto et al., Biol. Chem., 383 (2002), 715-721]. In this study, we investigated whether vitamin E, another potent antioxidative nutrient, also had beneficial effects on the muscle protein catabolism. However, daily intragastric supplementation of 1.5 or 15 mg/rat of alpha-tocopherol did not prevent weight loss of hindlimb skeletal muscle in tail-suspended rats. To elucidate the reason for the non-effectiveness of vitamin E, we further examined concentrations of oxidative stress markers, ubiquitination of muscle proteins and fragmentation of myosin heavy chain in gastrocnemius muscle of rats daily treated with 15 mg of alpha-tocopherol. Unexpectedly, vitamin E increased concentrations of glutathione disulfide and thiobarbituric acid-reactive substance and decreased glutathione level in the muscle, compared with those of vehicle treatment, indicating that vitamin E enhanced unweighting-induced oxidative stress in skeletal muscle. The vitamin E supplementation did not suppress the ubiquitination of muscle proteins and fragmentation of myosin heavy chain caused by tail-suspension. Our results suggest that supplementation of a relative high dose of vitamin E could not inhibit ubiquitin-dependent degradation of muscle protein in tail-suspended rats possibly due to its prooxidant action.
Ikemoto
Madoka
M
Department of Nutrition, School of Medicine, University of Tokushima.
Okamura
Yoshihito
Y
Kano
Mihoko
M
Hirasaka
Katsuya
K
Tanaka
Reiko
R
Yamamoto
Taeko
T
Sasa
Takahiro
T
Ogawa
Takayuki
T
Sairyo
Koichi
K
Kishi
Kyoichi
K
Nikawa
Takeshi
T
D000818:Animals; D015153:Blotting, Western; D003546:Cysteine Endopeptidases / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D019417:Hindlimb Suspension / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D009097:Multienzyme Complexes / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D046988:Proteasome Endopeptidase Complex; D051381:Rats; D017208:Rats, Wistar; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism*; D014810:Vitamin E / Q000008:administration & dosage*
D009097:Multienzyme Complexes; D009124:Muscle Proteins; D017392:Thiobarbituric Acid Reactive Substances; D025801:Ubiquitin; D014810:Vitamin E; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D018995:Myosin Heavy Chains; D005978:Glutathione; D019803:Glutathione Disulfide