Post-hatching ontogeny of intestinal proton-coupled folate transporter and reduced folate carrier in broiler chickens

Folate transporters, including the reduced folate carrier and the proton-coupled folate transporter, encoded by Slc19a1 and Slc46a1 genes respectively, play important roles in the transport of folate across biological membranes given the hydrophilic nature of folates. Although a number of studies have demonstrated that these two transporters are regulated ontogenetically in mammals, little data are available on their developmental patterns of expression in poultry. The objective of this study was to investigate the expression patterns of Slc19a1 and Slc46a1 in jejunal and cecal tissue of broiler chickens during post-hatching development. Post-hatch male chicks (Ross × Ross) had free access to water and a soybean/wheat-based diet. Jejunal, cecal and blood samples were collected on day-of-hatch but before feeding (D0), and on D2, D7, D14, D21 and D35 post-hatch (n = 8 at each time point), respectively. Plasma folate concentrations were low on the day of hatch and increased with maturation; by contrast, plasma homocysteine, a marker of folate status, was highest (P < 0.05) in the day-of-hatch birds and decreased thereafter. Increasing age reduced mRNA abundance of Slc19a1 (P < 0.05) in the jejunum and cecum. Abundance of Slc46a1 mRNA (P < 0.05) gradually decreased in the cecum with increasing age and that of Slc46a1 in the jejunum initially decreased and then increased to level similar to that of day-of-hatch. The study provides some initial data on ontogenetic regulation of Slc19a1 and Slc46a1 in the jejunum and cecum of the chicken and lays the ground work for future nutritional studies. Moreover, the expression of Slc19a1 and Slc46a1 transcripts in the cecum provides evidence of the potential for cecally derived folate to contribute to the folate status of the host.