Production of specific antibodies against GABA transporter subtypes (GAT1, GAT2, GAT3) and their application to immunocytochemistry.

Polyclonal subtype-specific antibodies were developed against three subtypes of GABA transporters (GAT1, GAT2 and GAT3). By immunoblot analysis, each antibody detected a single band that could be blocked by absorption of the antibody with the respective antigen. GAT2 was found in various tissues, while GAT1 and GAT3 were detected only in the brain. GAT1 was distributed throughout the brain with the highest amount in the olfactory bulb, CA3 region of the hippocampus, layer I of the cerebral cortex, piriform cortex, superior colliculus, interpeduncular nucleus and nucleus spinal tract of the trigeminal nerve, while the GAT3 was densely found in the olfactory bulb, thalamus, hypothalamus, pons and medulla, globus pallidus, central gray, substantia nigra, deep cerebellar nuclei and nucleus spinal tract of the trigeminal nerve but not in the hippocampus, cerebral cortex, caudate-putamen and cerebellar cortex. GAT2 immunoreactivity was faint throughout the brain but was concentrated in the arachnoid and ependymal cells. Both GAT1 and GAT3 were found in the neuropil but not in the cell bodies nor in the white matter. These results suggest that GAT1, GAT2 and GAT3 are expressed in different cells and that GAT1 and GAT3 are involved in distinct GABAergic transmission while GAT2 may be related to non-neuronal function.