A methionine deficient diet enhances adipose tissue lipid metabolism and alters anti-oxidant pathways in young growing pigs

Methionine is a rate-limiting amino-acid for protein synthesis but non-proteinogenicroles on lipid metabolism and oxidative stress have been demonstrated. Contrary torodents where a dietary methionine deficiency led to a lower adiposity, an increasedlipid 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 differentaspects of tissue lipid metabolism and anti-oxidant pathways in young pigs. Postweanedpigs (9.8 kg initial body weight) were restrictively-fed diets providing either anadequate (CTRL) or a deficient methionine supply (MD) during 10 days (n=6 pergroup). At the end of the feeding trial, pigs fed the MD diet had higher lipid content insubcutaneous adipose tissue. Expression levels of genes involved in glucose uptake,lipogenesis but also lipolysis, and activities of NADPH enzyme suppliers weregenerally higher in subcutaneous and perirenal adipose tissues of MD pigs, suggestingan increased lipid turnover in those pigs. Activities of the anti-oxidant enzymessuperoxide dismutase, catalase and glutathione reductase were increased in adiposetissues and muscle of MD pigs. Expression level and activity of the glutathioneperoxidase were also higher in liver of MD pigs, but hepatic contents in the reducedand oxidized forms of glutathione and glutathione reductase activity were lowercompared with control pigs. In plasma, superoxide dismutase activity was higher buttotal anti-oxidant power was lower in MD pigs. These results show that a dietarymethionine deficiency resulted in increased levels of lipogenesis and lipolytic indicatorsin porcine adipose tissues. Decreased glutathione content in the liver and coordinatedincrease of enzymatic antioxidant activities in adipose tissues altered the cellular redoxstatus of young pigs fed a methionine-deficient diet. These findings illustrate that arapidly growing animal differently adapts tissue metabolisms when facing aninsufficient methionine supply.