High 3H-vesamicol binding in ALS motor neurons – autoradiographic visualization of hyperactivity?
Objectives – To evaluate if increased metabolic demand in remaining motor neurons in ALS spinal cord sections can be visualized by 3H-vesamicol binding. Material and methods – As a presumed marker of the vesicular acetylcholine transporter, 3H-vesamicol was applied in quantitative autoradiography in cervical spinal cord sections from 11 ALS patients and 4 control cases. The regional binding was compared to that of the muscarinic ligand 3H-QNB. Results – Our results demonstrate the same magnitude of 3H-vesamicol binding in the ventral 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 3H-vesamicol binding for the cholinergic transporter is high in the motor neuron area, and sigma-sites constitute a minor proportion. Conclusion – The lack of decrease in 3H-vesamicol binding in postmortem ALS spinal cord sections probably reflects an upregulated synthesis of vesicular membranes in remaining and hyperactive motor neurons in vivo.
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