Multi-Omics Profiling of mTBI-Induced Gut–Brain Axis Disruption: A Preliminary Study for Biomarker Screening and Mechanistic Exploration

<b>Background/Objectives:</b> Mild Traumatic Brain Injury (mTBI) is a prevalent form of cranial trauma that can elicit a range of acute and chronic neuropsychiatric symptoms, and may increase the risk of neurodegenerative diseases. Its accurate identification remains a significant challenge in the field of forensic medicine. This study aimed to identify differential gut microbiota as potential biomarkers following mTBI and to preliminarily explore the association between alterations in gut microbiota and brain metabolites. <b>Methods:</b> An animal model was used to induce mTBI in male Sprague-Dawley (SD) rats. Dynamic changes in the gut microbiota and brain metabolites were analyzed via 16S rRNA sequencing and untargeted metabolomics. <b>Results:</b> Key discriminative taxa included <i>Staphylococcus</i>, <i>Streptococcus</i>, and <i>Aeromonadaceae</i>. Concurrently, brain metabolites, such as C24:1 Sphingomyelin and Thioetheramide PC, exhibited significant alterations. Multi-omics integration revealed that these changes were strongly correlated; in addition, a pathway analysis implicated disruptions in short-chain fatty acid and glycerophospholipid metabolism, which were linked to the regulation of inflammatory factors. <b>Conclusions:</b> This study demonstrates that mTBI induces distinct, time-dependent alterations in both the gut microbiota and brain metabolome, thereby providing a novel direction for research into the forensic diagnosis and mechanistic investigation of mTBI. Future studies are warranted to validate these potential biomarkers in human cohorts and to further elucidate the causal mechanisms underlying gut-brain axis interactions.