Temporal and spatial pattern of DNA damage in neurons following spinal cord Injury in mice

Abstract

BackgroundDeficient DNA repair and excessive DNA damage contribute to neurodegenerative disease. However, the role of DNA damage and repair in spinal cord injury (SCI) is unclear. SCI, a debilitating disruption of the structural and biological network of the spinal cord, is characterized by oxidative stress. Nevertheless, the pathophysiological mechanisms leading to neuronal loss following SCI remain incompletely defined. Methods: Using a contusion model, a severe SCI was induced at the L1 spinal level in C57Bl/6J mice. The temporal and spatial presence of DNA damage was then determined via immunolabeling for the DNA damage marker, gamma H2AX, from 1 h post-injury (hpi) to 28 days post-injury (dpi). Results: Our analysis revealed that increased DNA damage foci were present from 1 hpi to 3 dpi in SCI mice relative to controls (sham surgery and naive), with the damage signal spreading over time longitudinally from the affected area to more rostral and caudal regions. Co-labeling of gamma H2AX with NeuN revealed neuronal specificity of DNA damage, with increased early cell death (pan-nuclear gamma H2AX) peaking at 1 dpi and apoptosis (cleaved Caspase-3) arising later at 3 dpi. Conclusion: Our study indicates a possible role of DNA damage in neuronal loss following SCI and highlights the need for early interventions targeting DNA repair to preserve neuronal tissue.