GABA and GAD-like immunoreactivity in the primate retina

GABA immunoreactivity was studied and compared with GAD immunoreactivity in the retinae of baboon, cynomolgus monkey and man. The central and peripheral parts of the retinae were investigated separately in cynomolgus monkey and in man. The same kinds of structures were stained with both antisera. Cells with a position corresponding to amacrine cells were stained, as well as processes in the inner plexiform layer and some cells in the ganglion cell layer. The outer plexiform layer and some cells with the position and configuration of horizontal cells also appeared immunoreactive. Staining was also observed in bipolar-like cells, in man most clearly when using the GABA antiserum in sections from the central parts of the retina. It is possible that horizontal cells, as well as bipolar-like cells, may play a previously unsuspected role in GABAergic transmission in the primate retina.