Autoradiographic localization of [3H]gamma-amino-butyric acid in the myenteric plexus of the guinea-pig small intestine.

Localization of [3H]GABA in the guinea-pig myenteric plexus has been studied using light microscopic autoradiography. In the presence of beta-alanine, 10(-3) M, an inhibitor of glial cell high affinity GABA transport, [3H]GABA was transported by a high affinity uptake system into neuronal elements of the plexus. Scattered neurones accumulating [3H]GABA showed localization of silver grains over the soma and axonal processes. In addition a large population of uptake sites for [3H]GABA was found within the secondary and tertiary meshworks of the plexus so that dense accumulations of silver grains were observed localized over distinct 'tracts' within all three meshworks of the plexus. These results are considered to provide strong evidence for GABAergic neurons in the enteric nervous system.