High H-3-vesamicol binding in ALS motor neurons - autoradiographic visualization of hyperactivity?

To evaluate if increased metabolic demand in remaining motor neurons in ALS spinal cord sections can be visualized by H-3-vesamicol binding. Material and methods - As a presumed marker of the vesicular acetylcholine transport er, H-3-vesamicol was applied in quantitative autoradiography in cervical s pinal cord sections from 11 ALS patients and 4 control cases. The regional binding was compared to that of the muscarinic ligand H-3-QNB, Results - Ou r results demonstrate the same magnitude of H-3-vesamicol binding in the ve ntral horn of ALS spinal cord as compared to controls, despite the profound loss of motor neurons in that specific area in ALS. The specificity of H-3 -vesamicol binding for the cholinergic transporter is high in the motor neu ron area, and sigma-sites constitute a minor proportion. Conclusion - The l ack of decrease in H-3-vesamicol binding in postmortem ALS spinal cord sect ions probably reflects an upregulated synthesis of vesicular membranes in r emaining and hyperactive motor neurons in vivo.