Neurons and glia in cat superior colliculus accumulate [3H] gamma‐aminobutyric acid (GABA)

Abstract

We have examined by autoradiography the labeling pattern in the cat superior colliculus following injection of tritiated gamma‐aminobutyric acid (GABA). Silver grains were heavily distributed within the zonal layer and the upper 200 m̈m of the superficial gray. Fewer grains were observed deeper within the superficial gray, and still fewer were found within the optic and in‐termediate gray layers. The accumulation of label was restricted to certain classes of neuron and glia. Densely labeled neurons were small (8—12 m̈m in diameter) and located primarily within the upper 200 m̈m. Dark oligodendrocytes and as‐trocytes showed a moderate accumulation of label while pale oligodendrocytes and microglia were unlabeled. Label was also selectively accumulated over sev‐eral other types of profile within the neuropil, including presynaptic dendrites, axons, and axon terminals.