Binding to the glycine site of the NMDA receptor complex in brains of patients with Alzheimer's disease.

Ligand binding and in vitro receptor autoradiography were used to measure [3H]glycine binding to the modulatory site associated with the glutamate N-methyl-D-aspartate (NMDA) receptor in 4 areas of control and Alzheimer's disease brains. Binding of [3H]glycine to membranes prepared from temporal cortex was significantly reduced in Alzheimer's disease brains. Saturation analysis showed reductions in both the affinity of binding and the maximum number (Bmax) of binding sites. Autoradiograms of [3H]glycine binding in temporal cortex sections did not show a statistically significant reduction in binding in Alzheimer's disease. The findings suggest that in Alzheimer's disease the glycine modulatory site of the NMDA receptor complex is affected to a small extent by the loss of glutamatergic terminals which has previously been demonstrated.