Alanyl-glutamine supplementation regulates mTOR and ubiquitin proteasome proteolysis signaling pathways in piglets

Abstract Objective The aim of the present study was to investigate the effects of the alanyl-glutamine dipeptide (Ala-Gln) or the combination supplementation of free alanine and glutamine (Ala+Gln) on the mammalian target of rapamycin (mTOR) and ubiquitin-proteasome proteolysis (UPP) signaling pathways in piglets. Methods We randomly allocated 180 piglets to three treatments with three replicates of 20 piglets each, fed with diets containing 0.62% Ala, 0.5% Ala-Gln, 0.21% Ala+0.34% Gln, respectively. The duration of the experiment was 28 d. Results The results showed that Ala-Gln increased average daily gain of piglets, and decreased the ratio of feed to gain ( P P P P  > 0.05). Ala-Gln supplementation inhibited the mRNA expressions of MAFbx and MuRF1 in skeletal muscle of piglets ( P Conclusion Taken together, Ala-Gln supplementation improved the growth performance of piglets, enhanced the metabolism of Gln, upregulated protein synthetic signaling in liver and skeletal muscle and decreased protein degradative signaling in muscle of piglets. Moreover, these effects of Ala-Gln were more effective than those of Ala+Gln.