Ontogenic expression of the amino acid transporter b(0,+)AT in suckling Huanjiang piglets: effect of intra-uterine growth restriction.

Intestinal amino acid (AA) transport is critical for the supply of AA to other tissues. Few studies regarding AA intestinal transport systems during the period from postnatal intense development of piglets until weaning are available. In the present study, we measured the intestinal expression of b(0,+)AT according to developmental stage using the suckling Huanjiang piglet model, and documented the effect of intra-uterine growth restriction (IUGR) on such expression using real-time PCR and Western blot analysis. Suckling piglets that recovered after IUGR and those with normal body weights (NBW) were used after birth or at 7, 14 and 21 d of age. Blood samples were used for the measurement of plasma AA concentrations, and the jejunum was collected for the measurement of b(0,+)AT expression. In NBW piglets, b(0,+)AT expression was markedly decreased from days 0 to 21 (P< 0.01) and remained at a low level during all the suckling periods. In IUGR piglets, there was a marked decrease in b(0,+)AT expression at birth, which remained lower, when compared with NBW piglets, during the suckling period. These results coincided with decreased plasma arginine concentration at birth and decreased lysine concentration in 21-d-old piglets (P< 0.05). It is concluded that the high expression of b(0,+)AT at birth decreases during the suckling period, and that IUGR is associated with decreased expression of this apical AA transporter. The possible causal relationship between decreased b(0,+)AT expression and lower body weight of IUGR piglets in the suckling period is discussed.