Uptake and transport of 3H-GABA (γ-aminobutyric acid) injected into the cat dentate nucleus

Abstract

The uptake and transport of γ-aminobutyric acid (GABA) by neurons in the cat dentate nucleus were studied using light microscopy autoradiography after injections of 3H-GABA into the nucleus. Injections of 3H-GABA were also made into the overlying cerebellar cortex to provide positive evidence for uptake of the label in each experiment. In autoradiographs where labeled neurons were observed in the cortex, 3H-GABA was also observed to be incorporated by some dentate neurons. Along the periphery of the injection sites in the dentate nucleus, some neuronal soma and their processes were very heavily labeled as indicated by the dense accumulation of autoradiographic silver grains overlying those neuronal elements. Immediately adjacent there were nonlabeled neurons which were quite conspicuous due to the paucity of silver grains overlying their cell bodies and processes. Labeled axons were also observed leaving the injected regions of the dentate nucleus. Some labeled fibers coursed from the lateral and ventrolateral edge of the nucleus into the corpus medullare and the white matter of individual cerebellar folia. These axons could not, however, be traced into the cortex. Other labeled axons projected from the ventromedial hilus of the dentate into the brachium conjunctivum. These results demonstrate an uptake and intraaxonal transport system for 3H-GABA within the cat dentate nucleus.