Dietary N-carbamylglutamate or L-arginine supplementation improves hepatic energy status and mitochondrial function and inhibits the AMP-activated protein kinase-peroxisome proliferator- activated receptor γ coactivator-1α-transcription factor A pathway in intrauterine-growth-retarded suckling lambs

The objective of this study was to investigate the effects of dietary administration of L-arginine(Arg)or N-carbamylglutamate(NCG)on hepatic energy status and mitochondrial functions in suckling Hu lambs with intrauterine growth retardation(IUGR).Forty-eight newborn Hu lambs of 7 d old were allocated into 4 treatment groups of 12 lambs each,in triplicate with 4 lambs per replicate(2 males and 2 females)as follows:CON(lambs of normal birth weight,4.25±0.14 kg),IUGR(3.01±0.12 kg),IUGR+1%Arg(2.99±0.13 kg),or IUGR+0.1%NCG(3.03±0.11 kg).The experiment lasted for 21 d,until d 28 after birth,and all lambs were fed milk replacer as a basal diet.Compared with IUGR lambs,NCG or Arg administration increased(P<0.05)the adenosine triphosphate(ATP)level and the activities of com-plexes I/III/IV,isocitrate dehydrogenase and citrate synthase in the liver.Compared with CON lambs,the relative mRNA levels of adenosine monophosphate-activated protein kinaseα1(AMPKα1),peroxisome proliferator-activated receptorγcoactivator-1α(PGC1α)and transcription factor A(TFAM)were increased(P<0.05)in the liver of IUGR lambs,but were decreased(P<0.05)in the liver of NCG-or Arg-treated lambs compared with those in the IUGR lambs.Compared with IUGR lambs,NCG or Arg administration decreased(P<0.05)the total AMPKα(tAMPKα)-to-phosphorylated AMPKα(pAMPKα)ratio and the protein expression of PGC1αand TFAM.The results suggested that dietary Arg or NCG supplements improved hepatic energy status and mitochondrial function and inhibited the AMPK-PGC1α-TFAM pathway in IUGR suckling lambs.