Comparison of the effects of the M1-receptor antagonist telenzepine and the CCK-receptor antagonist loxiglumide on the pancreatic secretory response to intraduodenal tryptophan in dogs

Long-term bile diversion enhances basal and duodenal oleate-stimulated pancreatic exocrine secretion in dogs

There have been no previous reports whether long-term bile diversion enhances pancreatic exocrine secretion. The aim of this study was to elucidate the effect of long-term bile diversion on pancreatic exocrine secretion. Four mongrel dogs were prepared for chronic gastric and pancreatic fistulas and received intraduodenal sodium oleate infusion (controls). These dogs, then underwent diversion of bile from the intestines by ligating the common bile duct and interposing a segment of jejunum between the gallbladder and the urinary bladder (total biliary diversion [TBD]). After three weeks, the dogs received an identical sodium oleate infusion. TBD augmented basal pancreatic exocrine secretion compared with controls (4.4-fold increase in basal flow volume; 9.0-fold increase in bicarbonate output; and 3.3-fold increase in protein output). Likewise, TBD augmented oleate-stimulated exocrine secretion (2.0-fold increase in cumulative flow volume; 2.6-fold increase in bicarbonate output; and 1.4-fold increase in protein output). TBD also augmented basal and oleate-stimulated plasma cholecystokinin levels. Administration of a Cholecystokinin-A receptor antagonist (loxiglumide) after TBD reduced the flow volume and bicarbonate output to the control levels, and the protein output to less than a half of the control level. Long-term bile diversion enhances basal and oleate-stimulated pancreatic exocrine secretion, at least partly via increased cholecystokinin secretion.

Control of pancreatic exocrine secretion via muscarinic receptors: which subtype(s) are involved? A review

The present report gives an overview of the experimental, pharmacological and molecular investigations that have been undertaken during the past two decades to characterize and identify the muscarinic receptor subtype(s) involved in the cholinergic control of pancreatic exocrine secretion in humans and different animal species. The results published in the literature clearly indicate that both M1 and M3 receptors contribute to the regulation of pancreatic enzyme secretion, although contradictory conclusions have been drawn from secretory studies using specific M1 and M3 receptor antagonists in vivo and in vitro. Binding studies using specific M1 and M3 receptor antagonists have supported the existence of both M1 and M3 receptors on pancreatic acinar cells, which was confirmed by the demonstration of specific mRNA for both receptor subtypes in rat pancreatic acinar cells. In addition, experimental evidence exists that nonacinar (possibly presynaptic) M1 receptors also contribute to the control of pancreatic enzyme secretion. The role of the different muscarinic receptor subtypes in the control of pancreatic fluid and bicarbonate output, however, still needs to be clarified. Future research should cover the evaluation of the relative contribution of the different receptor subtypes to the regulation of pancreatic exocrine function, the localization of the receptors involved as well as possible species differences.