5-Hydroxytryptamine Induces Electrogenic Secretion in the Duodenum of Gerbil (Gerbillus cheesmani)

Abstract

The effect of serosally added 5-hydroxytryptamine (5-HT 100 µM) on the short circuitcurrent (Isc) across duodenum taken from fed, starved (4 days, water ad lib) and undernourished (50% control food intake for 21 days) gerbils (Gerbillus cheesmani) were investigated. The effect of the neurotoxin, tetrodotoxin (TTX 10 µM) and atropine (100µM) on the maximum increase in Isc induced by 5-HT were also studied. The 5-HT-induced Isc were higher in unstripped than in the stripped sheets in the three feeding conditions. TTX reduced the maximum increase in Isc induced by 5-HT across stripped and unstripped sheets taken from fed, starved and undernourished gerbils. Atropine decreased the 5-HT-induced Isc of stripped sheets in the three feeding conditions and it also decreased the 5-HTinduced Isc in unstripped sheets in fed duodenum. Therefore, the duodenal response to 5-HT occur partly by activation of a nonneural pathway and partly by activating electrogenic ion transport via muscarinic neural mechanism. It also showed that the 5-HT-induced Isc was chloride-dependent in fed duodenum and were chloride and bicarbonate dependent in the duodenum taken from starved and undernourished gerbil The results also showed that the increase in 5-HT-induced Isc as a results of starvation and undernourishment were TTX-sensitive and both chloride and bicarbonate dependent.