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

Distribution of the inhibitory neurotransmiter GABA was studied in the gold en hamster retina using immunocytochemistry at cellular and subcellular lev els. GABA-immunoreactivity was observed in somata of amacrine, displaced am acrine and horizontal cells. GABA immunoreactive fibers were abundant in th e inner plexiform layer. Ultrastructural analysis exhibited dense GABA-immu noreactive deposits in amacrine cell somata, processes and terminals. Immun olabelling was also observed in the cytoplasm of horizontal or interplexifo rm cells and displaced amacrine cells. In every case DAB deposits were obse rved in the cytosolic compartment, attached to the inner surface of cell me mbranes and to outer mitochondrial membranes. Immunolabeled terminals predo minated in the inner plexiform layer and immunoprecipitates were also obser ved attached to the outer face of vesicle membranes as well as completely f illing synaptic vesicles. Both clear and dense core vesicles were observed. The present results are similar to those obtained in other mammalian speci es showing GABA immunoreactivity in amacrine, displaced amacrine and horizo ntal cells.