Presence of gamma-aminobutyric acid transporter mRNA in interneurons and principal cells of rat hippocampus

After release, neurotransmitters are removed from the extracellular space b y high-affinity uptake. Specific sodium-dependent transporters serve this f unction for the inhibitory transmitter gamma-aminobutyric acid (GABA). Howe ver, it is largely unknown to which proportion GABA is taken up by GABAergi c interneurons, glia cells or principal neurons. We analyzed the distributi on of mRNA for the main GABA-transporter subtype in the hippocampus, GAT-1, in adult rats. Most interneurons were strongly stained for GAT-1 mRNA, ind icating re-uptake by the GABA-releasing cells. Surprisingly, prominent sign als for GAT-1 were also found throughout the principal cell layers (granule and pyramidal cells). These data indicate that GABA transporters may be pr esent in non-GABAergic projection cells of the rat hippocampus which contri bute to the clearance of GABA from the extracellular space. (C) 2000 Elsevi er Science Ireland Ltd. All rights reserved.