Central and peripheral serotonergic influences on viscerovisceral inhibitory reflex during duodenal distension in sheep

• Published in: Digestive diseases and sciences 1993-06, Vol.38 (6), p.1079-1086
• Main Authors: Brikas, P, Kania, B F, Fioramonti, J, Bueno, L
• Format: Article
• Language: English
• Subjects: Animals; Central Nervous System - drug effects; Central Nervous System - physiology; Dilatation; Dose-Response Relationship, Drug; Duodenum - drug effects; Duodenum - physiology; Female; Gastrointestinal Motility - drug effects; Injections, Intravenous; Injections, Intraventricular; Life Sciences; Peripheral Nerves - drug effects; Peripheral Nerves - physiology; Receptors, Serotonin - drug effects; Receptors, Serotonin - physiology; Reflex - drug effects; Reflex - physiology; Serotonin Antagonists - administration & dosage; Serotonin Antagonists - pharmacology; Sheep - physiology; Stomach, Ruminant - drug effects; Stomach, Ruminant - physiology; Viscera - drug effects; Viscera - physiology
• ISSN: 0163-2116; 1573-2568
• DOI: 10.1007/BF01295724

The effects of duodenal distension on forestomach and abomasal motility were investigated in conscious sheep chronically fitted with intraparietal electrodes, a duodenal cannula, and an intracerebroventricular cannula. Duodenal distensions with a balloon inflated with 40 ml (DD40) of water reduced the frequency of forestomach and abomasal contractions by 45 and 32%, respectively, while distension with 80 ml (DD80) induced a total inhibition. Methysergide, a mixed 5HT1-5HT2 antagonist administered intravenously (200 micrograms/kg) or intracerebroventricularly (20 micrograms/kg) suppressed the DD40-induced inhibition and reduced that induced by DD80. Spiroxatrine, a selective 5HT1A antagonist, intravenously (100 micrograms/kg) or intracerebroventricularly (10 micrograms/kg), suppressed the DD40 and DD80-induced inhibition, which was also attenuated by the 5HT2 antagonist ritanserin given intravenously (200 micrograms/kg) or intracerebroventricularly (20 micrograms/kg). Granisetron, a 5HT3 antagonist, injected intravenously (150 micrograms/kg), abolished the effects of DD40 and DD80 while it had no antagonistic action on DD40 and DD80 when given intracerebroventricularly (15 micrograms/kg). It is concluded that in sheep, duodenal distension inhibits forestomach and abomasal motility through 5HT1A and 5HT2 receptors at the level of the central nervous system and 5HT3 receptors located peripherally.