Neurotensin elevates hepatic bile acid secretion in chickens by a mechanism requiring an intact enterohepatic circulation

Neurotensin (NT), given intravenously at 10–50 pmol/kg per min to anesthetized female chickens equipped with a bile duct fistula, dose-dependently elevated hepatic bile flow and bile acid output but only when the enterohepatic circulation was maintained by returning the bile to the intestinal lumen. Infusion of NT at 10 and 50 pmol/kg per min increased the average hepatic bile acid output over a 30-min period to 138±11 and 188±13% of control, respectively. During infusion of NT, plasma levels of immunoreactive NT (iNT) increased in time from the basal level (14±1.3 pM) to reach steady state at 30 min. There was a near linear relationship between the dose of NT infused and the increment in plasma iNT. In addition, infusion of NT at 40 pmol/kg min gave a plasma level of iNT (≅88 pM) which was within the range of those observed during duodenal perfusion with lipid (54–300 pM) and near to that measured in hepatic portal blood from fed animals (52±5 pM). Perfusion of duodenum with lipid released endogenous NT and increased the rate of hepatic bile flow. When NT antagonist SR48692 was given, bile flow rate decreased to the basal level. These results suggest that intestinal NT, released by lipid, may participate in the regulation of hepatic bile acid output by a mechanism requiring an intact enterohepatic circulation.