Autoradiographic studies indicate regional variations in the characteristics of L-glutamate transporters in the rat brain.

Quantitative autoradiography of [3H]L-aspartate binding in thaw-mounted sections of rat brain has shown that L-trans-pyrrolidine-2,4-dicarboxylate and D-threo-3-hydroxyaspartate but not DL-2 aminoadipate strongly interacted with the binding sites while dihydrokainate, kainate and beta-aminoadipate produced only weak effects. The potency of inhibitors did not vary from one region to another in the telencephalon (neocortex, hippocampus and neostriatum) but, D-threo-3-hydroxyaspartate, L-trans-pyrrolidine-2,4-dicarboxylate, kainate and dihydrokainate inhibited [3H]L-aspartate binding in the cerebellar cortex less potently than that in the forebrain. Characteristics of the known excitatory amino acid transporters can, in part, explain the present results but contributions from additional transporter molecules to the heterogeneity of [3H]L-aspartate binding sites cannot be ruled out.