High-affinity uptake of [3H]GABA by submucous ganglion cells, nerve fibres and peri- and para-vascular fibres in guinea-pig and rat intestine.
Segments of the intestinal wall from the guinea-pig and rat were dissected, and laminae from the submucous layer subjected to light microscopic [3H]GABA autoradiography. The laminae were carefully prepared so that their planar arrangement could be easily viewed. Intense labelling of fine processes by [3H]GABA was found in the different laminae of the submucous including Henle's or Schabadasch's plexus, the vascular nerve plexus, and a network of fibres subjacent to the muscularis mucosae. This labelling was extensive and represented neuronal-specific high-affinity uptake of radiolabelled GABA. The pattern of labelling was different between the laminae; however, within individual laminae, the distribution of labelled fibres was characteristic of the local nerve networks. Ganglia displayed intense labelling of neuropil and ganglion cells. These results provide strong evidence for the presence of GABAergic nerve cells and processes in the mammalian intestinal submucosa.