Effects of ramosetron on gastrointestinal transit of guinea pig

Abstract

Background/Aims: A selective 5-hydroxytryptamine (5-HT)3 receptor antagonist, ramosetron, inhibits stress-induced abnormal defecation in animals and is currently used as a therapeutic drug for irritable bowel syndrome with diarrhea. The aim of this study is to investigate the effect of ramosetron on altered gastrointestinal (GI) transit. Materials and Methods: Male guinea pigs weighing approximately 300 g were used. The effect of ramosetron was investigated on altered GI transit induced by thyrotropin-releasing hormone (TRH), 5-HT, or mustard oil (MO). GI transit was evaluated by the migration of charcoal mixture from the pylorus to the most distal point, and expressed as a percentage (%) of charcoal migration (cm) of the total length of total small intestine (cm). Results: The average charcoal transit was 51.3 ±20.1% in the control (vehicle) group, whereas in the ramosetron group charcoal moved 56.6 ±21.9, 46.9 ±9.14, and 8.4 ±5.60% of the total small intestine at the concentrations of 10, 30 and 100 µg/kg, respectively. GI transit after administration of TRH (100 ug/kg), 5-HT (10 mg/kg), or MO (10 mg/kg) was accelerated compared to vehicle (5-HT, 94.9 ±9.22%; TRH, 73.4 ±14.7%; MO, 81.0 ±13.7%). Ramosetron inhibited GI transit altered by 5-HT, TRH, or MO. Conclusion: Ramosetron modulated GI transit. We suggest that ramosetron may be therapeutically useful for those with accelerated upper GI transit.