Pretreatment with probiotics (Bacillus safensis NMCC-189 and Bacillus clausii) prevents epileptogenesis in mice via modulation of BBB integrity, oxidative stress, and neurotransmitter balance

Epilepsy remains a difficult neurological condition to treat using conventional therapies. Emerging evidence links gut microbiota to the onset and progression of neurological disorders, including epilepsy. In this study, pretreatment with Bacillus safensis NMCC-189 and Bacillus clausii (probiotics) on epileptogenesis was evaluated. The probiotics were administered orally (10⁸ CFU/ml/day) for 14 days, followed by PTZ administration (60 mg/kg i.p) on day 14. The colon length, biochemical/microbiological analysis of fecal matter with oxidative stress markers, confirmed the colonization of the colon with the bacterium in the mice and improved colon health. The mice supplemented with the probiotics bacteria showed significant anticonvulsant effects via delaying onset, reducing severity and duration of the seizures with no mortality in comparison to the non-supplemented PTZ-kindled mice. Protective action in the supplemented mice can be explained by reduced oxidative stress in the brain tissue. Moreover, RT-PCR results showed that prior administration of Bacillus safensis NMCC-189 and Bacillus clausii successfully restored the expression of tight junction (ZO-1, Occludin, Claudin), and normalized glutamatergic (NR1, NR2A, NR2B, mGluR1, GluA1, GluA2) and GABAergic (GABRA1, GABRB1) gene expression altered by PTZ administration, indicating strong neuroprotective and barrier-preserving effects. These findings highlight the potential of probiotics to mitigate excitotoxicity, restore neurotransmitter balance, and protect epithelial and blood–brain barriers in epilepsy. This study highlights Bacillus safensis NMCC-189 and Bacillus clausii as promising probiotics that modulate gut microbiota and exhibit neuroprotective effects, targeting key mechanisms of epileptogenesis. Furthermore, being part of microbial flora, these probiotics lack any side effects, unlike traditional anti-epileptic drugs.