GABA-immunoreactivity in ganglion cells of the rat retina

Ganglion cells in the rat retina were labeled with the fluorescent dye, Diamidino-yellow, by retrograde transport from the superior colliculus and subsequently reacted for GABA-like immunoreactivity with a rhodamine-conjugated antiserum. Examination of sectioned retinas by fluorescence microscopy showed double labeling in approximately 6% of the ganglion cells. The presence of GABA in these neurons suggests that they may be involved in providing direct inhibitory input to the rat tectum.