Adaptive response of equine intestinal Na+/glucose co-transporter (SGLT1) to an increase in dietary soluble carbohydrate

Pflugers Arch. 2009 Jun;458(2):419-30. doi: 10.1007/s00424-008-0620-4. Epub 2008 Dec 2.


Experimental and epidemiological evidence suggests that consumption of hydrolyzable carbohydrate, hCHO (grain), by horses is an important risk factor for colic, a common cause of equine mortality. It is unknown whether the small intestinal capacity to digest hCHO and/or to absorb monosaccharides is limiting, or even if horses can adapt to increased carbohydrate load. We investigated changes in the brush-border membrane carbohydrate digestive enzymes and glucose absorptive capacity of horse small intestine in response to increased hCHO. Expression of the Na(+)/glucose co-transporter, SGLT1, was assessed by Western blotting, immunohistochemistry, Northern blotting, QPCR, and Na(+)-dependent D-glucose transport. Glucose transport rates, SGLT1 protein, and mRNA expression were all 2-fold higher in the jejunum and 3- to 5-fold higher in the ileum of horses maintained on a hCHO-enriched diet compared to pasture forage. Activity of the disaccharidases was unaltered by diet. In a well-controlled study, we determined SGLT1 expression in the duodenal and ileal biopsies of horses switched, gradually over a 2-month period, from low (<1.0 g/kg bwt/day) to high hCHO (6.0 g/kg bwt/day) diets of known composition. We show that SGLT1 expression is enhanced, with time, 2-fold in the duodenum and 3.3-fold in the ileum. The study has important implications for dietary management of the horse.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological
  • Animals
  • Dietary Carbohydrates / pharmacology*
  • Female
  • Glucose Transporter Type 2 / biosynthesis
  • Horses
  • Ileum / drug effects
  • Ileum / metabolism
  • Immunohistochemistry
  • Jejunum / drug effects
  • Jejunum / metabolism
  • Male
  • Microvilli / metabolism
  • RNA, Messenger / metabolism
  • Sodium-Glucose Transporter 1 / biosynthesis
  • Sodium-Glucose Transporter 1 / metabolism*
  • Solubility
  • Sucrase / metabolism
  • alpha-Glucosidases / metabolism


  • Dietary Carbohydrates
  • Glucose Transporter Type 2
  • RNA, Messenger
  • Sodium-Glucose Transporter 1
  • alpha-Glucosidases
  • Sucrase