Analyzing the Relationship Between Motor Unit Counts and CHAT/β-Tubulin Expression Following Spinal Cord Injury

Introduction: Immunofluorescence labeling of Choline Acetyltransferase (CHAT) and β-tubulin enables visualization of cholinergic activity and axonal integrity, respectively. CHAT serves as a biomarker for motor neuron function, while β-tubulin indicates axonal regeneration. This study investigates the correlation between the CHAT/β-tubulin ratio and electrophysiological motor unit count (MUC) in spinal cord injury patients.

Methods: Eighteen patients who underwent nerve transfer surgery were included. Prior to surgery, Electromyography was carried out to determine optimal donor muscles, and MUCs were obtained. Immunofluorescence staining for CHAT and β-tubulin was performed on nerve tissue samples obtained during the procedures. The CHAT/β-tubulin ratio was calculated. Pearson’s correlation coefficient was utilized to analyze the relationship between the CHAT/β-tubulin ratio and MUC.

Results: A significant relationship was observed between the CHAT/β-tubulin ratio and MUC (r = -0.49, p = 0.039). These findings suggest that these biomarkers are associated with the MUC analysis. An increased CHAT/β-tubulin ratio, indicating more CHAT or less β3-Tubulin, corresponds with a decreased motor unit count in the corresponding muscle prior to sample collection.

Conclusion : The above data indicate a direct relationship between MUC and β -Tubulin, and an inverse relationship between MUC and CHAT. This direct relationship is likely a result of decreased axons following denervation. The relationship between CHAT and MUC could indicate that following denervating injuries, acetyltransferase is upregulated in an attempt to activate lost motor units. Further studies are necessary to determine how these findings relate to reinnervation following nerve transfer procedures.