Projections and chemical coding of neurons with immunoreactivity for nitric oxide synthase in the guinea-pig small intestine

Neurosci Lett. 1992 Dec 14;148(1-2):121-5. doi: 10.1016/0304-3940(92)90819-s.


The distribution of nitric oxide synthase (NOS) immunoreactivity was investigated in the guinea-pig small intestine. There were many immunoreactive nerve cell bodies in the myenteric plexus but very few in submucous ganglia. NOS immunoreactivity was not found in non-neuronal cells except for rare mucosal endocrine cells. Abundant immunoreactive nerve fibres in both myenteric and submucous ganglia, and in the circular muscle, arose from myenteric nerve cells whose axons projected anally along the intestine. NOS immunoreactivity coexisted with VIP-immunoreactivity, but not with substance P immunoreactivity. We conclude that nitric oxide synthase is located in a sub-population of enteric neurons, amongst which are inhibitory motor neurons that supply the circular muscle layer.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Oxidoreductases / analysis*
  • Animals
  • Female
  • Fluorescent Antibody Technique
  • Ganglia, Sympathetic / cytology
  • Ganglia, Sympathetic / enzymology
  • Guinea Pigs
  • Immunohistochemistry
  • Intestine, Small / innervation*
  • Male
  • Muscle, Smooth / innervation
  • Myenteric Plexus / cytology
  • Myenteric Plexus / enzymology*
  • Neurons / cytology*
  • Neurons / enzymology*
  • Nitric Oxide Synthase
  • Vasoactive Intestinal Peptide / analysis


  • Vasoactive Intestinal Peptide
  • Nitric Oxide Synthase
  • Amino Acid Oxidoreductases