Role of 5-HT3 receptors in peristaltic reflex elicited by stroking the mucosa in the canine jejunum

• Published in: The Journal of physiology Vol. 471; no. 1; pp. 159 - 173
• Main Authors: Neya, T, Mizutani, M, Yamasato, T
• Format: Journal Article
• Language: English
• Published: England The Physiological Society 01-11-1993
• Subjects: Animals; Atropine - pharmacology; Dogs; Female; Hexamethonium; Hexamethonium Compounds - pharmacology; Indoles - pharmacology; Intestinal Mucosa - drug effects; Intestinal Mucosa - innervation; Intestinal Mucosa - physiology; Jejunum - drug effects; Jejunum - innervation; Jejunum - physiology; Male; Neural Pathways - drug effects; Neural Pathways - physiology; Nifedipine - pharmacology; Ondansetron - pharmacology; Peristalsis - drug effects; Peristalsis - physiology; Physical Stimulation; Receptors, Serotonin - drug effects; Receptors, Serotonin - physiology; Reflex - drug effects; Reflex - physiology; Serotonin Antagonists; Tetrodotoxin - pharmacology; Tropisetron
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/jphysiol.1993.sp019895

1. The role played by the 5-HT3 receptor, a serotonin subtype receptor, in peristaltic reflexes was studied in dogs first
given ketamine, then anaesthetized with urethane (1.0 g kg-1, I.V.) and alpha-chloralose (100 mg kg-1, I.V.). The jejunal
loop was partitioned into two segments with respect to blood supply. Drugs were infused intra-arterially into each segment.
2. Stroking of the mucosa of the aboral and oral segments elicited an ascending contraction and a descending relaxation, respectively.
3. The ascending contraction was concentration-dependently inhibited by treatment of the aboral segment with the 5-HT3 receptor
antagonists ICS 205-930 and ondansetron (1.4 pmol min-1 to 14 nmol min-1 for both). The maximal inhibition was 49.5 and 69.3%,
respectively. The response was not affected by treatment of the oral segment with these drugs. The descending relaxation was
inhibited by 51.4 and 60.8%, respectively, by treatment of the oral segment with ICS 205-930 and ondansetron (1.4 nmol min-1
for both). 4. The ascending contraction was markedly inhibited by treatment of either segment with hexamethonium (140 nmol
min-1). The response was abolished by treating both segments with hexamethonium and by treating the oral segment with atropine
(14 nmol min-1). 5. These results suggest firstly that, in the canine jejunum, enteric neurons with 5-HT3 receptors play a
role as sensory neurons or interneurons in the ascending excitatory and the descending inhibitory pathways of the peristaltic
reflex elicited by stroking the mucosa, and secondly, that the ascending limb is composed of cholinergic interneurons and
motoneurons.