Effects of dietary methionine deficiency on adipose tissue growth and oxidative status in piglets
Résumé
Adipose tissue plays a crucial role in energy balance, but excessive fat deposition may be linked to systemic
oxidative stress. Methionine (Met) is the second limiting amino acid (AA) for growth in pigs and a precursor
for cysteine, one of the three AA of the antioxidant glutathione, so that the Met supply could modify the
antioxidant status. This study aimed to determine the effects of dietary Met deficiency on the development
of adipose tissue and redox metabolism. Weaned piglets (9 kg BW) received a diet providing either an
adequate (CTRL) or a deficient supply in Met (-33%, REST) during 10 days (n=6 per group). At a similar
BW, the dietary Met restriction led to a 29% increase in perirenal fat proportion, an 11% increase in lipid
content in subcutaneous adipose tissue, and greater activities of lipogenic enzymes in both sites. These
changes were associated with greater expression levels of genes involved in glucose uptake (GLUT4),
lipogenesis (FASN, ME1) and lipolysis (HSL, ATGL and PLIN2) in the two adipose tissues. The activities
of the anti-oxidative enzymes superoxide dismutase (SOD), catalase and gluthatione reductase (GRX) were
increased in both adipose tissues of REST piglets compared to CTRL piglets. The oxidized glutathione
content in adipose tissues was also greater in REST piglets, but the reduced form did not vary between
groups. The total antioxidant activities in plasma (as assessed by free radical scavenging and ferric reducing
ability) were lower in REST piglets. In conclusion, a dietary Met deficiency changed the partitioning of
energy towards a greater adiposity and modified the redox status of adipocytes with consequences on the
antioxidant capacity of piglets.
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