Inter-digestive and post-prandial antro-pyloro-duodenal motor activity in humans: Effect of 5-hydroxytryptamine 1 receptor agonism

Background: Little is known about the effect of 5-hydroxytryptamine 1 (5-HT₁) receptor agonism on the co-ordinated motor activity of the gastric antrum, pylorus and duodenum under fasting and fed conditions. Aim: To evaluate the effect of sumatriptan, a 5-HT₁ agonist, on fasting and fed antro-pyloro-duodenal motility. Methods: In study 1, antro-pyloro-duodenal motility was recorded for two phase IIIs of the migrating motor complex and then, following either a subcutaneous injection of sumatriptan 6 mg or saline control, for at least one additional phase III in 11 healthy volunteers (21-36 years). In study 2, the post-prandial motility was recorded for 3 h after either a subcutaneous injection of sumatriptan 6 mg or saline control in 10 healthy volunteers (18-36 years). Results: Sumatriptan prolonged the migrating motor complex cycle (P = 0.009) by increasing the duration of phase II (P = 0.02) but not phases I and III. Postprandially, sumatriptan reduced the activity index (P = 0.017) by reducing the frequency of co-ordinated motor activity involving the antrum and/or the duodenum (P < 0.05). Conclusion: 5-HT₁ receptor agonism increases the periodicity of the migrating motor complex and reduces the occurrence of post-prandial co-ordinated motor activity involving the gastric antrum, pylorus and duodenum.