Ciprofloxacin-induced microbiota dysbiosis triggers seizure susceptibility through the microbiota-gut-brain axis

Background: Epilepsy is linked to inflammation and gut microbiota dysbiosis. Ciprofloxacin-induced microbiota disruption may increase seizure susceptibility. This study investigates underlying mechanisms and the therapeutic potential of fecal microbiota transplantation (FMT). Methods: A total of 64 male Sprague-Dawley rats were categorized into four experimental groups: Control (CTRL), Ciprofloxacin-treated (CPF), CPF with fecal microbiota transplantation (CPF-FMT), and CPF with phosphate-buffered saline (CPF-PBS). Gut microbiota dysbiosis was induced with ciprofloxacin for 14 days, followed by either FMT or PBS for 14 days. Seizure susceptibility was assessed using pentylenetetrazole (PTZ), alongside molecular analyses of gut and blood-brain barrier integrity, neuroinflammatory markers, and cortical transcriptomics. Results: Microbiota dysbiosis was associated with increased seizure susceptibility, accompanied by disruption of intestinal and blood-brain barrier (BBB) integrity, thereby exacerbating systemic and neuroinflammation. Dysbiotic rats exhibited significant reductions in microbial diversity and depletion of protective taxa, including f_Muribaculaceae, f_Prevotellaceae, and Lachnospiraceae_NK4A136_group, which correlated with intestinal barrier dysfunction. This dysfunction was associated with reduced tight junction proteins (ZO-1, Occludin, Claudin-5) and inflammatory cell infiltration. Systemic inflammation and disrupted blood-brain barrier integrity resulted in microglial activation and astrocytic proliferation in the brain. Notably, FMT was related to restoration of microbial diversity, improvement of barrier-related markers, attenuation of neuroinflammatory responses, and a reduction in seizure susceptibility. Conclusion: This study provides evidence linking gut microbiota dysbiosis to seizure susceptibility through neuroinflammatory processes, contributing to the understanding of gut-brain axis involvement in fluoroquinolone-induced seizures.