Distribution of GABA in the golden hamster retina. An immunocytochemical study

Distribution of the inhibitory neurotransmitter GABA was studied in the golden hamster retina using immunocytochemistry at cellular and subcellular levels. GABA-immunoreactivity was observed in somata of amacrine, displaced amacrine and horizontal cells. GABA immunoreactive fibers were abundant in the inner plexiform layer. Ultrastructural analysis exhibited dense GABA-immunoreactive deposits in amacrine cell somata, processes and terminals. Immunolabelling was also observed in the cytoplasm of horizontal or interplexiform cells and displaced amacrine cells. In every case DAB deposits were observed in the cytosolic compartment, attached to the inner surface of cell membranes and to outer mitochondrial membranes. Immunolabeled terminals predominated in the inner plexiform layer and immunoprecipitates were also observed attached to the outer face of vesicle membranes as well as completely filling synaptic vesicles. Both clear and dense core vesicles were observed. The present results are similar to those obtained in other mammalian species showing GABA immunoreactivity in amacrine, displaced amacrine and horizontal cells.