Evidence for interactions between [ 3H]glutamate and [ 3H]kainic acid binding sites in rat striatal membranes. Possible relevance for kainic acid neurotoxicity

Abstract

In vitro studies have shown that kainic acid (10 −6 M) but not N-methyl- d-aspartate (NMDA) in the same concentration reduces the number of striatal [ 3H]glutamate binding sites and increases their affinity in striatal membranes. In vitro studies also show that l-glutamate (10 −8 M) but not NMDA (10 −6 M) increases the number of [ 3H]kainic acid binding sites and reduces their affinity in striatal membranes. Ibotenic acid (10 −6 M) can also reduce the affinity of [ 3H]kainic acid binding sites in striatal membranes. These results give indications for the existence of bidirectional receptor-receptor interactions between two receptors for excitatory amino acids in local striatal circuits. These interactions could partly explain the involvement of glutamate in kainate neurotoxicity.