A light and electron microscopic study of GAT-1-positive cells in the cerebral cortex of man and monkey.

Specimens of human cerebral cortex were obtained during neurosurgical operations and studied by immunocytochemistry and electron microscopy, using antibodies to the GABA transporter GAT-1. Cortical material from macaque monkeys was prepared similarly. Large numbers of GAT-1-positive non-pyramidal neurons were observed in layers I, II, V, and VI of the cortex. Electron microscopy also showed that the GAT-1-positive axon terminals formed symmetrical and not asymmetrical synapses, suggesting that they were the terminals of non-pyramidal neurons. Processes of cells in the walls of blood vessels were also labelled. We conclude that GAT-1 is present in cell bodies and axon terminals of non-pyramidal neurons, and a population of mural cells in blood vessels, in the primate cerebral cortex.