3H-kainic acid binding: relevance for evaluating the neurotoxicity of kainic acid.

Binding of ³H-kainic acid (KA) to brain membranes is saturable (K_D = 72 nM) and displays markes specificity for compounds that bear relation to excitatory amino acids. Its regional distribution correlates roughly with the regional neurotoxicity of in situ KA injections. Striatal kainate lesions, but not interruption of striatal afferents, reduce striatal KA binding by 36%. This decrease is due to a loss in the number of neuronal binding sites without affecting the affinity for the ligand. It is suggested that ³HKA binding to neuronal elements may be a valuable instrument for studies of the mechanism of neuronal degeneration caused by KA.