Expression of GABA transporter subtypes (GAT1, GAT3) in the adult rabbit retina

Abstract

Purpose: GABA transporters (GATs) are of importance for GABA signal systems. They have previously not been examined in rabbit retina, nor has their correlation with neurotransmitter GABA and GABA receptors been examined in the retina of any species. Methods: The distribution of GATs, GABA and GABA receptors was examined with immunohistochemical methods. Results: Both GAT1 and GAT3 immunoreactivities were found in the inner plexiform layer and in amacrine cells. GAT3 was also present in Muller cells. GAT1 appeared in amacrine cells that also had a high GABA concentration, but not in cells with moderate to low GABA concentration. GAT1 was also present in amacrine cells that did not show GABA immunoreactivity, possibly indicating a postsynaptic GABA uptake system. Conclusion: GAT3 is probably involved in both neuronal and glial GABA uptake whereas GAT1 is involved in predominantly neuronal uptake, and possibly also into non-GABA-ergic amacrine cells. Further, there may be at least two populations of GABA containing neurons.