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

The effects of excitatory amino acids (EAAs) upon transporter-mediated gamm a -aminobutyric acid (GABA) release were investigated in cells containing t yrosine hydroxylase (TH) or nitric oxide synthase (NOS) in retina of the pr imate Cebus apella. Retinas were treated in vitro with 50 muM Kainate (KA) or 5 mM L-Glutamate (L-Glu), for 30 min at 37 degreesC, in an Mg2+-free Loc ke's solution with or without Ca2+. The effects of EAAs were measured immun ocytochemically by determining the GABA content in TH or NOS-immunoreactive cells in the inner retina, after stimulation. L-Glu and KA induced a Ca2+- independent GABA release from most GABA-immunoreactive cells of the inner r etina. Double label experiments indicated that this release occurs in NOS+/ GABA(+) cells, but not in TH+/GABA(+) cells suggesting that these cell subp opulations may be differentiated in some functional aspects. (C) 2001 Elsev ier Science Ireland Ltd. All rights reserved.