(+)‐[3H]MK‐801 Binding Sites in Postmortem Human Brain

Abstract
The pharmacological specificity and the regional distribution of the N-methyl-D-aspartate receptor-associated 5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-imine maleate (MK-801) binding sites in human postmortem brain tissue were determined by binding studies using (+)-[3H]MK-801. Scatchard analysis revealed a high-affinity (KD= 0.9 ± 0.2 nM, Bmax= 499 ± 33 fmol/mg of protein) and a low-affinity (KD= 3.6 ± 0.9 nM, Bmax= 194 ± 44 fmol/ mg of protein) binding site. The high-affinity site showed a different regional distribution of receptor density (cortex > hippocampus > striatum) compared to the low-affinity binding site (cerebellum > brainstem). The rank order pharmacological specificity and stereoselectivity of the high-(cortex) and low-(cerebellar) affinity binding sites were identical. However, all compounds tested showed greater potency at the high-affinity site in cortex. The results indicate that (+)[3H]MK-801 binding in human postmortem brain tissue shows pharmacological and regional specificity.