Immunohistochemical localization of substance P NK1 receptor in guinea pig distal colon

A. M. Harrington, J. M. Hutson, Bridget R. Southwell

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24 Citations (Scopus)


Background: Neurokinin receptors facilitate tachykinin mediated intestinal motility and secretion. Distribution of Substance P (SP) neurokinin 1 receptor (NK1r) immunoreactivity (IR) has been previously characterized in guinea pig ileum, but not colon. This study localizes NK1rs in guinea pig distal colon. Methods: Neurons were double labelled for NK1r and either acetylcholine transferase (ChAT), calbindin (calb), neuropeptide Y (NPY), nitric oxide synthase (NOS) or SP. The NK1r endocytosis was induced by 10-5 mol L-1 SP, septide, [SarMet] SP or neurokinin A. Results: In guinea pig distal colon, NK1r-IR was present on 70% of submucosal neurons. Sixty-three percent of the NK1r-IR submucosal neurons were ChAT-IR, 16% calb/SP-IR, 19% NPY-IR and 14% NOS-IR neurons. The NK1r-IR was present on 5% of my enteric neurons. Of these 63% were ChAT-IR, 16% calb-IR neurons and 25% NOS-IR. The NK1rs were also on myenteric plexus interstitial cells of Cajal and on circular muscle. Conclusion: In guinea pig distal colon, NK1rs were on 70% of submucosal neurons including all three secretomotor neuron subtypes and sensory neurons, suggesting NK1rs have a major role in neuronal control of mucosal reflexes. The NK1rs were on few myenteric neurons but were dense on muscle cells, suggesting NK1rs affect motility through neuro-muscular rather than neuro-neuronal transmission.

Original languageEnglish
Pages (from-to)727-737
Number of pages11
JournalNeurogastroenterology and Motility
Issue number5
Publication statusPublished - 1 Oct 2005
Externally publishedYes


  • Colon
  • Enteric nervous system
  • Guinea pig
  • Immunohistochemistry
  • Neurokinin 1 receptor
  • Substance P


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