AMYOTROPHIC-LATERAL-SCLEROSIS - QUANTITATIVE AUTORADIOGRAPHY OF [H-3] MK-801/NMDA BINDING-SITES IN SPINAL-CORD

We have characterized a high-affinity binding site for [H-3]MK-801, an NMDA receptor ion channel antagonist, in cervical spinal cords from patients who have died with amyotrophic lateral sclerosis (ALS) and from control subjects. In cervical spinal cord [H-3]MK-801 labelled at least two binding sites, the highest affinity site having a K(d) of between 9-16 nM. No significant differences in affinity were observed between spinal cords from ALS patients or controls, In spinal cords from ALS patients, large reductions in [H-3]MK-801 receptor binding (between 30-40% reductions) were detected in both the dorsal and ventral horns. These data may reflect the death of receptor-bearing cells, or a form of receptor regulation.