Effect of caloric restriction and subsequent re-alimentation on oxidative stress in the liver of Hu sheep ram lambs

摘要

Growing animals under moderate caloric restriction (CR) exhibit compensatory growth upon ad libitum feeding, while the influence of oxidative stress under this phonotype in ruminants is poorly understood. The objective of this study was to investigate the antioxidant defenses and mitochondrial function in the liver of Hu sheep ram lamb in response to two months of CR (55% feeding) and subsequent three months of ad libitum. In this study, the expressions of antioxidase related genes (SOD2, CAT and GPX1) and mitochondrial biogenesis related genes (AMPK, PPARGC1A and TFAM) were examined in the liver, as well as the activities of antioxidase enzymes and the hepatic mitochondrial function. Results indicated that lambs tended to compensate for growth loss, and liver oxidative stress was limited by CR and subsequent re-alimentation. CR also activated PPARGC1A and TFAM, and elevated the relative mtDNA copy number, which could be recovered by subsequent re-alimentation. Likewise, re-alimentation restored the reduced complex I activity and H2O2 production associated with low mitochondrial potential with CR treatment. In addition, AMPK phosphorylation at Thr172 was activated and SIRT1 expression was enhanced in CR lambs, while showed a decreased tendency after re-alimentation. Altogether, our findings demonstrated that moderate CR and subsequent re-alimentation induced "efficient" mitochondria biogenesis as an adaptation mechanism, which maintained the dynamic balance of oxidant-antioxidant system by activating AMPK-PPARGC1A-TFAM pathway in the liver of Hu sheep ram lambs.