Spatial, temporal and sex specific mitochondrial dynamic changes in severe controlled cortical impact mouse model of traumatic brain injury

Abstract

Traumatic brain injury (TBI) triggers complex and evolving secondary cascades that disrupt mitochondrial homeostasis and contribute to progressive neurodegeneration. Although mitochondrial impairment is a well-recognized driver of post-traumatic pathology, the spatial and temporal progression of mitochondrial dysfunction, particularly in regions distal to the injury site, remains poorly defined, and potential sex-specific responses remain understudied. Here, we performed a comprehensive mitochondrial-focused analysis in a mouse model of controlled cortical impact (CCI), quantifying mtDNA copy number (mtDNA-CN), mitochondrial gene expression, and protein markers regulating biogenesis, transcription, electron transport chain integrity, and mitophagy. Mitochondrial profiles were assessed across four brain regions (cortex at 2, 4, and 6 mm from the injury epicenter, and hippocampus) at four time points (6h, 12h, 24h, and 48h) in both female and male C57BL/6J mice. While mtDNA content exhibited only modest and region-restricted reduction, particularly near the injury core, transcriptional and protein-level changes were far more pronounced and sex-divergent. Females displayed extensive early cortical gene activation followed by widespread hippocampal suppression at 48 h across mitochondrial dynamics, OXPHOS, transcriptional regulation, and biogenesis pathways, accompanied by 48h in PGC-1, TFAM, and NDUFS1. In contrast, males showed minimal transcriptional disruption but demonstrated delayed compensatory increases in TFAM, NDUFS1, and p62 protein levels, suggesting activation of mitochondrial maintenance and recovery programs. These spatially and temporally distinct responses reveal fundamental sex-specific vulnerabilities in mitochondrial regulation after TBI. Together, our findings provide a direction to an integrated mitochondrial landscape of early post-injury events and identifies critical windows and pathways that may support sex-specific therapeutic targeting to restore mitochondrial function after TBI.