Effect of deramciclane, a new 5-HT receptor antagonist, on cholecystokinin-induced changes in rat gastrointestinal...

Recent studies suggested that serotonin receptors may be involved in modulating the actions of cholecystokinin (CCK) in the gastrointestinal tract. The present work was designed to compare the effects of deramciclane, a recently developed serotonin-2 (5-HT2A/2C) receptor antagonist, and lorglumide, a CCK(A) receptor antagonist, on exogenous and endogenous CCK-induced pancreatic enzyme secretion and pancreatic growth, as well as on the emptying of the stomach and the gallbladder. Pancreatic secretory function was tested while CCK release was evoked by diversion of bile-pancreatic juice in rats. Adaptive growth of the pancreas was induced by chronic intragastric administration of camostate, a potent synthetic trypsin inhibitor in rats. Gastric emptying of a noncaloric test meal was investigated in response to intraduodenal intralipid infusion, also in rats. In fasted mice, gallbladder emptying was examined in response to intragastric egg yolk administration. In rats, diversion of bile-pancreatic juice from the duodenum stimulated pancreatic amylase secretion. This action was blocked by deramciclane and by lorglumide. Pancreatic hypertrophy and hyperplasia induced by chronic camostate administration was also suppressed by both the serotonin- and the CCK-receptor antagonists. Intraduodenal administration of intralipid induced a significant delay in gastric emptying. This effect was inhibited by both deramciclane and lorglumide in rats. In mice, intragastric administration of egg yolk elicited an accelerated release of bile from the gallbladder. Prior treatment with either deramciclane or lorglumide abolished this response. Lorglumide was able to inhibit the functional responses elicited by exogenous CCK administration in both pancreas, stomach and gallbladder, while deramciclane was not effective under such circumstances. Our data show that deramciclane inhibited the effects of CCK on pancreatic, gastric and gallbladder function when its endogenous release was stimulated, but did not alter the effects of exogenously administered peptide. These results suggest that serotonin, primarily via 5-HT2A receptors, may modulate CCK-mediated gastrointestinal functions in rats.