Abstract
Individuals with postnatal growth retardation (PGR) are prone to developing chronic disease. Abnormal development in small intestine is casually implicated in impaired growth performance. However, the exact mechanism is still unknown. In this present study, PGR piglets (aged 42 days) were employed as a good model to analyse changes in nutrient absorption and energy metabolism in the intestinal mucosa. The results showed lower serum concentrations of free amino acids, and lipid metabolites in PGR piglets, which were in accordance with the down-regulated mRNA expressions involved in fatty acid and amino acid transporters in the jejunal and ileal mucosa. The decreased activities of digestive enzymes and the marked swelling in mitochondria were also observed in the PGR piglets. In addition, it was found that lower ATP production, higher AMP/ATP ratio, deteriorated mitochondrial complex III and ATP synthase, and decreased manganese superoxide dismutase activity in the intestinal mucosa of PGR piglets. Furthermore, altered gene expression involved in energy metabolism, accompanied by decreases in the protein abundance of SIRT1, PGC-1α and PPARγ, as well as phosphorylations of AMPKα, mTOR, P70S6K and 4E-BP1 were observed in intestinal mucosa of PGR piglets. In conclusion, decreased capability of nutrient absorption, mitochondrial dysfunction, and aberrant energy status in the jejunal and ileal mucosa may contribute to PGR piglets.