The Role of Serotonin in Gastric Acid Inhibition by Duodenal Fat

Abstract

DOI: http://dx.doi.org/10.5915/13-1-11927 The possible role of serotonin (5-hydroxytryptamine) in the inhibition of gastric acid secretion following the infusion of fat into the duodenum was studied. Heidenhain pouches were constructed in 12 dogs and cannulae were placed in the dependent part of the pouch for the sample collection, the stomach for drainage and the duodenum for fat infusion. In all studies, histamine phosphate (0.04 mg/kg/hr) was infused during the four-hour study period. When fat (corn oil) was infused into the duodenum, gastric acid secretion gradually became inhibited (p<0.05 and a maximum inhibition of 59% (p<0.001) occurred at one hour. Following serotonin depletion by administering reserpine 24 hours prior to the study, gastric acid secretion increased (p<0.02) when compared to the effect of histamine infusion. Serotonin depletion by reserpine or antagonism by 1-methyl-lysergic acid butanolamide (UML491) significantly interfered (P<0.01) with the fat-induced inhibition of gastric acid secretion. Following serotonin depletion, replacement by 5-hydroxytryptophan restored (p<0.02) the inhibitory action of intraduodenal fat on gastric acid secretion. The data suggests that serotonin may be an enterogastrone which is at least partly responsible for the inhibition of gastric acid secretion following intraduodenal fat infusion.