Slowly digestible starch influences mRNA abundance of glucose and short-chain fatty acid transporters in the porcine distal intestinal tract

The relationship between starch chemistry and intestinal nutrient transporters is not well characterized. We hypothesized that inclusion of slowly instead of rapidly digestible starch in pig diets will decrease glucose and increase short-chain fatty acid (SCFA) transporter expression in the distal gut. Weaned barrows (n = 32) were fed 4 diets containing 70% starch [ranging from 0 to 63% amylose and from 1.06 (rapidly) to 0.22%/min (slowly) rate of in vitro digestion] at 3 x maintenance energy requirement in a complete randomized block design. Ileal and colon mucosa was collected on day 21 to quantify mRNA abundance of Na+-dependent glucose transporter 1 (SGLT1), monocarboxylic acid transporter 1 (MCT1), and Na+-coupled monocarboxylate transporter (SMCT). Messenger RNA was extracted and cDNA manufactured prior to relative quantitative reverse transcription PCR. Data were analyzed using the 2(-Delta) (Delta C)(T) method, with beta-actin and glyceraldehyde-3-phosphate dehydrogenase as reference genes, and regression analysis was performed. As in vitro rate of digestion decreased, SGLT1 linearly increased (P < 0.05) in the ileum. Contrary to SGLT1, MCT1 tended to linearly decrease (P = 0.08) in the ileum and increased quadratically (P < 0.001) in the colon with decreasing rate of digestion. Starch digestion rate did not affect SMCT in the ileum; however, colonic SMCT quadratically decreased (P < 0.01) with decreasing rate of digestion. In conclusion, in contrast to our hypothesis, slowly digestible starch increased ileal glucose and decreased ileal SCFA transporter mRNA abundance, possibly due to an increased glucose in the luminal ileum. Effects of starch on colonic SCFA transporter mRNA abundance were inconsistent.