COLOCALIZATION OF GABA-IMMUNOREACTIVITY IN NEUROPEPTIDE-CONTAINING AND MONOAMINE-CONTAINING AMACRINE CELLS IN THE RETINA OF BUFO-MARINUS

Immunocytochemical study was performed in the Bufo marinus retina to r eveal the localization of gamma-aminobutyric acid (GABA)-immunoreactiv ity in neuropeptide Y (NPY)-, substance P (SP)-, serotonin (5HT) and t yrosin hydroxylase (TH)-immunoreactive amacrine cells. GABA-immunoreac tivity was present in all NPY-, in some of the SP- and 5HT-containing amacrine cells, but not in TH-immunoreactive amacrine cells. Among the 5HT-immunoreactive amacrine cells, a population of 5HT-synthesizing a nd most of the 5HT-accumulating cells were GABA-immunoreactive. These results indicate that neuropeptide- and GABA-immunoreactivity are colo calized in amacrine cells of the anuran retina. We propose a possible co-transmission for two classical neurotransmitters (GABA and 5HT) in some of the 5HT-containing amacrine cells.