Zafirlukast Exacerbates Behavioral Seizure Activity and Blood-Brain Barrier Disruption Despite Modestly Reducing...

Epilepsy is one of the most prevalent neurological disorders worldwide, and approximately 25% of patients remain refractory to pharmacological treatment. Blood-brain barrier (BBB) disruption and reactive gliosis are key mechanisms implicated in early epileptogenesis. This study investigated the effects of zafirlukast, a leukotriene receptor antagonist, on BBB permeability, reactive gliosis, and behavioral seizure activity in a pentylenetetrazol (PTZ)-induced early epileptogenesis model in C57BL/6 mice. Zafirlukast was administered twice daily at a dose of 10 mg/kg. Seizure activity was evaluated by behavioral observation in terms of seizure severity, latency, duration, and frequency. BBB permeability was assessed using the Evans Blue assay, and brain tissues were analyzed by biochemical and immunohistochemical methods. The PTZ + ZAFIR group exhibited more severe seizures, characterized by increased seizure frequency and duration, shorter latency, and a higher kindling rate (80% vs. 27%). BBB permeability was also increased, whereas MMP-9 levels remained, suggesting disruption may be linked to direct mechanical effects of recurrent seizures rather than inflammation. Clues suggest that zafirlukast may exert paradoxical effects on two prominent cell types involved in reactive gliosis. While increased GFAP and TGF-β1 expression may reflect enhanced astrocyte activation, changes in IL-1β and Iba1 expression suggest suppression of microglial activation. Notably, pro-inflammatory and oxidative stress markers remained unchanged despite the increase in seizure severity. The observed reduction in neurodegeneration may be attributable to the suppressive effects of zafirlukast on microglial activation and the subsequent reduction in pro-inflammatory cytokine release. These findings indicate a complex role for leukotriene signaling during early epileptogenesis. Further studies using different doses, vehicles, and experimental models are warranted to clarify the effects of zafirlukast on the mechanisms underlying early epileptogenesis.