Exploring Pericontusional Temporal Metabolomic Changes after Controlled Cortical Impact in Mice

Traumatic brain injury (TBI) is a leading cause of trauma-related morbidity and mortality, yet metabolic responses in the injured brain remain incompletely understood. Metabolomic profiling of pericontusional tissue may enable the identification of acute-phase biomarkers and reveal novel therapeutic targets. Using a controlled cortical impact (CCI) model, we performed targeted metabolomic analysis of tricarboxylic acid (TCA) cycle intermediates, amino acids, and acylcarnitines at multiple time points within the first 72 h postinjury. We hypothesize that there is time-dependent mitochondrial dysfunction and impaired β-oxidation in the acute and sub-acute time points after injury. CCI was performed in adult male C57BL6/J mice (velocity 5 m/s, depth 1.2 mm) under isoflurane anesthesia. Pericontusional tissue was harvested at 2, 6, 24, and 72 h postinjury following transcardial saline perfusion (n = 8/group). Naïve and anesthesia-only sham animals served as controls; sham animals received isoflurane exposure without craniotomy to isolate anesthetic effects from surgical injury. Relative quantification of TCA cycle intermediates, amino acids, and acylcarnitines was performed by liquid chromatography-high resolution mass spectrometry; metabolite abundances were normalized to protein content. Data were analyzed by Student's t-test, and p value < 0.05 determined significance. Enrichment analysis of metabolite profiles was conducted and visualized in MetaboAnalyst 6.0. Pericontusional tissue demonstrated time-dependent changes across the three metabolite classes, with two distinct temporal phases identified by dimensionality reduction: an acute phase (2-6 h) and a subacute phase (24-72 h). TCA cycle intermediates and glycolytic metabolites were broadly and progressively depleted, consistent with sustained mitochondrial dysfunction and energy failure. Acylcarnitines accumulated across multiple chain lengths, indicating impaired fatty acid β-oxidation. Amino acid profiles showed broad accumulation of essential and branched-chain amino acids-notably leucine and valine-alongside depletion of glutamate, alanine, and GABA, contrasting with prior reports of branch-chain amino acids depletion after TBI. Ingenuity Pathway Analysis confirmed broad suppression of amino acid catabolism, carbohydrate metabolism, and lipid oxidation pathways after CCI. Tryptophan catabolism via the kynurenine pathway was the sole upregulated metabolic pathway, consistent with indoleamine 2,3-dioxygenase 1-mediated neuroinflammatory signaling. We identified TBI-dependent alterations in key metabolic pathways within pericontusional tissue that may have implications for the development of biomarkers or metabolism-targeted therapies. Future investigations should explore cell type-specific metabolic changes and assess their correlation with clinically measurable metabolite levels.