Administration of ampicillin increases ileal Asbt protein amounts resulting in reduction of fecal bile acid excretion in mice

Abstract

Administration of the antibacterial drug ampicillin (ABPC) significantly decreased fecal bile acid excretion although it increased hepatic cholesterol 7α‐hydroxylation as well as CYP7A1 mRNA level. In the present study, we have investigated the mechanisms for the reduction of fecal bile acid excretion in ABPC‐treated mice. Bile acid amounts in small intestinal lumen and portal blood concentrations of bile acids were increased 1.6‐fold and 2.0‐fold, respectively, in ABPC‐treated mice. Ileal apical sodium‐dependent bile salt transporter (Asbt) mRNA levels were significantly increased in ABPC‐treated mice whereas ileal bile acid binding protein and organic solute transporter alpha and beta mRNA levels were reduced. Ileal Asbt protein amounts in brush border membranes were increased 2.5‐fold in ABPC‐treated mice. These results suggest that enhancement of ileal Asbt‐mediated bile acid absorption contributes to the reduction of fecal bile acid excretion in ABPC‐treated mice.