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This Article Full Text (PDF) All Versions of this Article: jas.2009-1992v1 88/1/306    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Liao, S. F. Articles by Matthews, J. C. PubMed PubMed Citation Articles by Liao, S. F. Articles by Matthews, J. C.

The small intestinal epithelia of beef steers differentially express sugar transporter mRNA in response to abomasal vs ruminal infusion of starch hydrolysate

Department of Animal and Food Sciences, University of Kentucky, Lexington, KY 40546-0215

jmatthew{at}uky.edu

Abstract

In mammals, the absorption of monosaccharides from small intestinal lumen involves at least 3 sugar transporters (ST): SGLT1 (gene SLC5A1) transports glucose and galactose, while GLUT5 (gene SLC2A5) transports fructose, across the apical membrane of entrocytes. In contrast, GLUT2 (gene SLC2A2) transports all of these sugars across both basolateral and apical membranes. To compare the distribution patterns and sensitivity to nutritional regulation of these 3 ST mRNA in beef cattle small intestinal tissue, 18 ruminally and abomasally catheterized Angus steers (BW 260 kg) were assigned to either water (control), ruminal cornstarch (partially hydrolyzed by -amylase; SH), or abomasal SH infusion treatments (n = 6) and fed an alfalfa-cube based diet at 1.3x NE_m requirement. The SH infusions amounted to 20% of ME intake. After 14- or 16-d of infusion, steers were killed, duodenal, jejunal, and ileal epithelia harvested, and total RNA extracted. The relative amount of ST mRNA in epithelia was determined using real-time RT-PCR quantification methods. Basal expression of GLUT2 and SGLT1 mRNA was greater (P < 0.09) by jejunal than by duodenal or ileal epithelia, whereas basal content of GLUT5 mRNA was greater (P 0.02) by jejunal and duodenal than by ileal epithelia. The content of GLUT5 mRNA in small intestinal epithelia was not affected (P 0.16) by either SH infusion treatment. In contrast, both GLUT2 and SGLT1 mRNA content in the ileal epithelium was increased (P 0.05) by 6.5- and 1.3-fold, respectively, after abomasal SH infusion. Duodenal SGLT1 mRNA content also was increased (P = 0.07) by 64% after ruminal SH infusion. These results demonstrate that the ileum of beef cattle small intestine adapts to an increased luminal supply of glucose by increasing SGLT1 and GLUT2 mRNA content, whereas increased ruminal SH supply results in duodenal upregulation of SGLT1 mRNA content. These adaptive responses of GLUT2 and SGLT1 mRNA to abomasal or ruminal SH infusion suggest that beef cattle can adapt to increase their carbohydrate assimilation through small intestinal epithelia, assuming that altered ST mRNA contents reflect the altered transport functional capacities.

Key Words: bovine • nutrient-gene interaction • SLC2 • SLC5 • small intestine