Cervical Spinal Cord Injury Induces Distinct Changes in Gut Microbiome Composition Over Time in Rats

Abstract

Nearly 60% of all spinal cord injuries (SCI) occur at the cervical level. These high‐level injuries can lead to quadriplegia, autonomic dysregulation, and interruption of the descending respiratory pathways required for breathing. As respiratory motor function is required for life, it is critical to restore breathing as soon as possible after cervical SCI. Indeed, therapeutic techniques in animal studies have been successful at restoring breathing function after SCI; however, these interventions appear to be more effective at chronic than acute timepoints post‐injury. One potential cause for this observation is the impact the injury has on the gastrointestinal (GI) tract and gut microbiome, which have previously been shown to have detrimental effects on recovery outcomes, including lower limb motor function and emotional affect as indicated by increased anxiety‐like behavior. However, the impact the gut microbiome has on the recovering spinal cord at different timepoints, levels, and injury severities still needs to be fully realized. We aimed to build upon these previous findings and investigate the impact of cervical SCI on the gut microbiome over time and up to chronic timepoints. We hypothesized that cervical SCI leads to transient changes in the gut microbiome, which are most severe acutely after injury impeding functional recovery of breathing, but resolve over time and thus eventually allow for more profound recovery. To test our hypotheses, we performed left C2 hemisections on adult female rats, collected fecal samples from injured, sham, and naïve animals, and assessed microbiome composition at various timepoints pre‐ and post‐injury. Preliminary results suggest that following cervical SCI (up to 12 weeks post injury), robust differences in gut microbiome are apparent compared to non‐injured animals. Future studies will classify bacterial identities and assess the impact of the post‐injury gut microbiome on respiratory motor function and plasticity, as well as inter‐institutional differences.