Comparative study of glutamate mediated γ-aminobutyric acid release from nitric oxide synthase and tyrosine hydroxylase immunoreactive cells of the Cebus apella retina

Abstract

The effects of excitatory amino acids (EAAs) upon transporter-mediated γ-aminobutyric acid (GABA) release were investigated in cells containing tyrosine hydroxylase (TH) or nitric oxide synthase (NOS) in retina of the primate Cebus apella. Retinas were treated in vitro with 50 μM Kainate (KA) or 5 mM l-Glutamate ( l-Glu), for 30 min at 37°C, in an Mg 2+-free Locke's solution with or without Ca 2+. The effects of EAAs were measured immunocytochemically by determining the GABA content in TH or NOS-immunoreactive cells in the inner retina, after stimulation. l-Glu and KA induced a Ca 2+-independent GABA release from most GABA-immunoreactive cells of the inner retina. Double label experiments indicated that this release occurs in NOS +/GABA + cells, but not in TH +/GABA + cells suggesting that these cell subpopulations may be differentiated in some functional aspects.