Peristalsis regulation by tachykinin NK1 receptors in the rabbit isolated distal colon

Luciano Onori, Annalisa Aggio, Gennaro Taddei, Maria F. Loreto, Rachele Ciccocioppo, Riccardo Vicini, Marcello Tonini

Research output: Contribution to journalArticlepeer-review


In the gastrointestinal tract, tachykinin NK1 receptors are widely distributed in a number of neuronal and nonneuronal cells involved in the control of gut motor activity. In particular, in the rabbit isolated distal colon, which is a suitable model system to investigate the contribution of tachykinins as noncholinergic excitatory transmitters, the influence of NK1 receptors in the regulation of peristalsis is not known. The selective NK1-receptor antagonists SR-140333 (0.3 and 1 nM) and MEN-10930 (0.3-10 nM) significantly enhanced the velocity of rabbit colonic propulsion to submaximal stimulation. The prokinetic effect of SR-140333 was prevented by Nω-nitro-L-arginine (L-NNA), a nitric oxide synthase inhibitor, indicating that NK1 receptors located on nitrergic innervation exert a functional inhibitory restraint on the circular muscle and probably on descending excitatory and inhibitory pathways during propulsion. Conversely, the selective NK1-receptor agonist septide (3-10 nM) significantly inhibited colonic propulsion. In the presence of L-NNA, the inhibitory effect of septide was reverted into a prokinetic effect, which is probably mediated by the activation of postjunctional excitatory NK1 receptors.

Original languageEnglish
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Issue number2 48-2
Publication statusPublished - Aug 1 2003


  • Excitatory pathways
  • Inhibitory pathways
  • Myenteric neurons

ASJC Scopus subject areas

  • Gastroenterology
  • Physiology


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