Boldo leaves reduce seizures, neuroinflammation, and hemichannel activity in a murine model of chronic epilepsy

Epilepsy is a chronic neurological disorder characterized by a propensity for seizures due to an imbalance between excitatory and inhibitory brain activity. This condition also induces neuroinflammation, which contributes to disease progression. Given that hemichannels (HCs) permeabilize the cell membrane of glia playing a critical role in neuroinflammation, we investigated the antiepileptic potential of Boldo (Peumus boldus M.), an endemic Chilean tree containing several bioactive molecules including boldine, a HC inhibitor. Mice were treated with pulverized Boldo leaves, the antiseizure medication valproate, or a combination of both for 5 days. Seizure severity was assessed in a pentylenetetrazole-induced kindling mouse model. Using the dye uptake technique, we evaluated the membrane permeability in hippocampal astrocytes, microglia, and neurons. Additionally, we analyzed astroglial and microglial reactivity and measured levels of pro-inflammatory cytokines (IL-1β, IL6, and TNF-α). Both Boldo and valproate significantly reduced seizure severity. However, distinct mechanisms were observed. Valproate administration increased dye uptake in control animals and enhanced glial reactivity, corroborating its established ability to stimulate hemichannel activity. Conversely, Boldo treatment, either alone or in conjunction with valproate, reduced these parameters, consistent with its HC-blocking properties. Importantly, Boldo was more effective than valproate in reducing plasmatic levels of inflammatory and oxidative stress markers. These findings indicate that Boldo, by inhibiting these HCs, could provide a valuable therapeutic strategy to mitigate neuroinflammation in epilepsy, highlighting the clinical potential of this readily available medicinal herb.