A light and electron microscopic study of GAT-1 positive cells in the monkey brainstem and spinal cord.

The distribution of the GABA transporter GAT-1 was studied in the monkey brainstem and spinal cord, using an affinity purified polyclonal antibody against a synthetic peptide corresponding to the C terminus of GAT-1. Very dense staining was observed in the interpeduncular nucleus, the inferior olivary nucleus and the substantia gelatinosa of the spinal cord, whilst dense labelling was observed in the substantia nigra, cochlear nuclei, vestibular nuclei, the spinal nucleus of V, the area postrema and the ventral horn of the spinal cord. Electron microscopy showed that the labelled profiles consisted of axon terminals that formed symmetrical synapses, consistent with GABAergic terminals. Many of the nuclei that were densely labelled for GAT-1 were those that received primary auditory, vestibular, or somatosensory inputs and the high density of GAT-1 in these nuclei suggests that GAT-1 plays an important role in terminating the inhibitory effects of GABA, at these nuclei.