An increased flux through the glucose 6-phosphate pool in enterocytes delays glucose absorption in Fxr^-/- mice

The farnesoid X receptor (FXR) is involved in regulation of bile acid and lipid metabolism. Recently, a role for FXR in control of glucose metabolism became evident. Because FXR is expressed along the length of the small intestine, we evaluated the potential role of FXR in glucose absorption and processing. During intravenous infusion of a trace amount of D-[6,6-²H₂]glucose, a D-[U-¹³C]glucose-enriched oral glucose bolus was given, and glucose kinetics were determined in wild-type and Fxr^-/- mice. Compared with wild-type mice, Fxr^-/- mice showed a delayed plasma appearance of orally administered glucose. Multicompartmental kinetic modeling revealed that this delay was caused by an increased flux through the glucose 6-phosphate pool in enterocytes. Thus, our results show involvement of FXR in intestinal glucose absorption, representing a novel physiological function for this nuclear receptor.