Dietary N-carbamylglutamate and L-arginine supplementation improves intestinal energy status in intrauterine-growth-retarded suckling lambs
This study explores the roles of L-arginine (Arg) and N-carbamylglutamate (NCG) supplementation in the diet in intestine damage, energy state, as well as the associated protein kinase signaling pathways activated by AMP in intrauterine growth retarded (IUGR) suckling lambs. A total of 48 newborn Hu lambs with a normal birth weight (CON) and those with IUGR were randomly divided into four groups, CON, IUGR, IUGR + 1% Arg, and IUGR + 0.1% NCG, with 12 animals in each group. All animals were fed for 21 days, from day 7–28, following birth. Our results indicated that the IUGR suckling Hu lambs in the Arg or NCG groups were associated with reduced (P < 0.05) plasma diamine oxidase (DAO) and D-lactic acid levels compared with IUGR suckling lambs. In addition, IUGR suckling Hu lambs in the Arg or NCG group were also linked with a higher (P < 0.05) villous height : crypt depth ratio (VCR), as well as villous height in the duodenum relative to those obtained for IUGR suckling Hu lambs. Relative to IUGR suckling Hu lambs, IUGR suckling Hu lambs in the Arg or NCG groups were found to have higher (P < 0.05) ATP, ADP and TAN contents, and AEC levels, and smaller (P < 0.05) AMP : ATP ratios in the duodenum, jejunum and ileum. Moreover, IUGR suckling Hu lambs in the Arg or NCG group were also linked with higher citrate synthase, isocitrate dehydrogenase and alpha-oxoglutarate dehydrogenase complex activities in the duodenum, jejunum and ileum compared with those found for IUGR suckling Hu lambs (P < 0.05), except for the activity of isocitrate dehydrogenase in the ileum. IUGR suckling Hu lambs in the Arg or NCG group were linked with a lower ratio of pAMPKα/tAMPKα and protein expression of Sirt1 and PGC1α in the ileum relative to those of the IUGR suckling Hu lambs (P < 0.05). Taken together, these findings show that supplementation of NCG and Arg in the diet can ameliorate intestinal injury, improve energy status, motivate key enzyme activities in the tricarboxylic acid (TCA) cycle, and also inhibit the AMP-activated protein kinase signaling pathways in IUGR suckling Hu lambs.