A methionine deficient diet enhances adipose tissue lipid metabolism and alters anti-oxidant pathways in young growing pigs
Résumé
Methionine is a rate-limiting amino-acid for protein synthesis but non-proteinogenic
roles on lipid metabolism and oxidative stress have been demonstrated. Contrary to
rodents where a dietary methionine deficiency led to a lower adiposity, an increased
lipid accretion rate has been reported in growing pigs fed a methionine deficient diet.
This study aimed to clarify the effects of a dietary methionine deficiency on different
aspects of tissue lipid metabolism and anti-oxidant pathways in young pigs. Postweaned
pigs (9.8 kg initial body weight) were restrictively-fed diets providing either an
adequate (CTRL) or a deficient methionine supply (MD) during 10 days (n=6 per
group). At the end of the feeding trial, pigs fed the MD diet had higher lipid content in
subcutaneous adipose tissue. Expression levels of genes involved in glucose uptake,
lipogenesis but also lipolysis, and activities of NADPH enzyme suppliers were
generally higher in subcutaneous and perirenal adipose tissues of MD pigs, suggesting
an increased lipid turnover in those pigs. Activities of the anti-oxidant enzymes
superoxide dismutase, catalase and glutathione reductase were increased in adipose
tissues and muscle of MD pigs. Expression level and activity of the glutathione
peroxidase were also higher in liver of MD pigs, but hepatic contents in the reduced
and oxidized forms of glutathione and glutathione reductase activity were lower
compared with control pigs. In plasma, superoxide dismutase activity was higher but
total anti-oxidant power was lower in MD pigs. These results show that a dietary
methionine deficiency resulted in increased levels of lipogenesis and lipolytic indicators
in porcine adipose tissues. Decreased glutathione content in the liver and coordinated
increase of enzymatic antioxidant activities in adipose tissues altered the cellular redox
status of young pigs fed a methionine-deficient diet. These findings illustrate that a
rapidly growing animal differently adapts tissue metabolisms when facing an
insufficient methionine supply.
Domaines
Alimentation et NutritionOrigine | Fichiers éditeurs autorisés sur une archive ouverte |
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