Expression of the chicken peptide transporter 1 and the peroxisome proliferator-activated receptor α following feed restriction and subsequent refeeding

Abstract

The peptide transporter 1 (PepT1) transports di- and tripeptides from the lumen of the small intestine into the enterocyte. Expression of this transporter is affected by numerous factors, including feed restriction. During a fasting state, PepT1 is thought to be regulated by peroxisome proliferator-activated receptor α (PPARα). The objective of this study was to evaluate the effects of a feed restriction-refeeding regimen on expression of chicken PepT1 and PPARα. Ten-day-old broiler chicks were placed on a 24-h feed restriction with 6 birds sampled before and after the restriction. Following feed restriction, the remaining birds were divided into 3 groups: continuously fasted, refed-food withdrawn, and refed ad libitum. The duodenum, jejunum, and ileum were sampled 1, 2, 3, 5, and 7 h post feed restriction. Expression of PepT1 and PPARα increased almost 2-fold post feed restriction (P < 0.002). A significant group × time interaction was observed for PPARα, with the continuously fasted group showing a peak at 29 h postrestriction (P = 0.002). A group × segment interaction was found for both PepT1 (P = 0.002) and PPARα (P = 0.01); within the continuously fasted group, PepT1 expression was greatest in the jejunum (P < 0.001) and ileum (P = 0.01) when compared with the duodenum. No difference was observed between the jejunum and ileum. The PPARα expression was greatest in the jejunum (P = 0.03) when compared with the duodenum, with no difference between the jejunum and ileum or between the duodenum and ileum. The increase in PepT1 expression during a time of reduced feed intake suggests the importance of having transporters ready to scavenge any available luminal nutrients. The concurrent increase in PPARα suggests a possible regulatory role for this receptor in the regulation of PepT1 during feed restriction.