Kainate neurotoxicity and glutamate inactivation.

Dihydrokainate, an inhibitor of high affinity L-glutamate as an excitant of cat spinal neurones in vivo. This action of dihydrokainate was selective in that the effects of excitants taken up actively in vitro by CNS tissue (L-aspartate, D- and L-glutamate and L-homocysteate) were enhanced whereas those of other substances not taken up (acetylcholine, D-homocysteate, kainate and N-methyl-D-aspartate) were not. Since kainate and dihydrokainate have similar potencies as inhibitors of L-glutamate uptake, interference with the inactivation of synaptically released L-glutamate may contribute to the neurotoxic effects of kainate.