A comparison of sodium-dependent glutamate binding with high-affinity glutamate uptake in rat striatum.
The specific sodium-dependent binding of [3H]glutamate to membranes of the rat striatum was examined and a comparison made with high affinity glutamate uptake. In the presence of sodium, [3H]glutamate binding was saturable and of high affinity. No binding could be detected in the absence of sodium. Removal of the cortical afferents to the striatum resulted in a parallel decrease in Na+-dependent glutamate binding and in high-affinity glutamate uptake. After the injection of the neurotoxin kainic acid into the striatum, the density of Na+-dependent glutamate binding sites was reduced by 40%, while high-affinity uptake showed no significant decrease. Drugs which inhibit high-affinity uptake were also effective at inhibiting Na+-dependent binding. The results suggest that about half the Na+-dependent glutamate binding sites in the striatum represent high-affinity uptake sites on the corticostriatal terminals. The remainder of the binding sites are located on striatal neurons and may also be uptake sites.
D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D002540:Cerebral Cortex / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D005971:Glutamates / Q000378:metabolism*; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D051381:Rats; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology*
D005971:Glutamates; D017981:Receptors, Neurotransmitter; D012964:Sodium; D007608:Kainic Acid