Autoradiographic localization of [ 3H] γ-aminobutyric acid in neuronal elements of the rat gastric antrum and intestine

Abstract

High-affinity uptake and localization of radiolabelled γ-aminobutyric acid (GABA) has been examined using light microscopic autoradiography in laminar preparations and transverse paraffin sections of the rat stomach, and small and large intestine. In the presence of β-alanine (10 −3 M), a substrate specific inhibitor of high-affinity GABA transport into glia, tritiated GABA was accumulated by a high-affinity uptake system into myenteric ganglia and a subpopulation of mucosal cells. In the small and large intestine high-affinity uptake of [ 3H]GABA was evident in myenteric ganglion cells, extra-ganglionic sites and in the deep muscular nerve plexus of the circular muscle layer. Such labelling could be prevented in tissue treated with the specific neuronal high-affinity uptake blocker, l-2,4-diaminobutyric acid dihydrochloride ( l-DABA; 10 −3 M), and therefore represented the selective distribution of [ 3H]GABA uptake sites to intrinsic neuronal elements of the rat gastrointestinal tract.