THE MYCOTOXIN, DEOXYNIVALENOL, DELAYS GASTRIC-EMPTYING THROUGH SEROTONIN-3 RECEPTORS IN RODENTS

The effects of the trichotecene mycotoxin, deoxynivalenol, on gastric emptying and intestinal propulsion in mice and rats and gastrointestin al myoelectrical activity in rats were investigated. Gastric emptying and intestinal transit were evaluated after gavage with a milk meal co ntaining a marker ((CrO4Na2)-Cr-51) and radioactivity was counted in t he stomach and 10 segments of the small intestine. The myoelectrical a ctivity of the antrum, duodenum and jejunum was assessed by implanting electrodes for long-term electromyographic recordings. Deoxynivalenol given orally (50-1000 mug/kg) but not i.c.v. (5 mug/kg) 10 min before the test meal inhibited gastric emptying in a dose-related manner. In testinal propulsion was reduced for the highest dose (1000 mug/kg) onl y. The inhibition of gastric emptying induced by deoxynivalenol was an tagonized by ondansetron and granisetron given s.c. (50 mug/kg) but no t by ondansetron i.c.v. (10 mug/kg). Metoclopramide, domperidone (1 mg /kg s.c.), methysergide, ritanserin and cisapride (2 mg/kg s.c.) did n ot modify the deoxynivalenol-induced inhibition of gastric emptying. I n rats, gavage with a 2.5-ml milk meal increased the frequency of antr al spike bursts from 1.9 +/- 0.9/min in the fasted state to 4.7 +/- 0. 4/min and disrupted intestinal migrating motor complexes for 84.9 +/- 10.8 min. Oral administration of deoxynivalenol (50-100 mug/kg) 1 0 mi n before the meal did not modify the frequency of antral spike bursts but induced migrating motor complexes on the small intestine after the meal. This effect was reversed by ondansetron (10 mug/kg s.c.). It wa s concluded that, in rodents, deoxynivalenol inhibits gastric emptying by inducing intestinal migrating motor complexes through a peripheral action at the serotonin-3 receptors.