Curcumin reduces development of seizurelike events in the hippocampal-entorhinal cortex slice culture model for epileptogenesis

Objective: Inhibition of the mammalian target of rapamycin (mTOR) pathway could be antiepileptogenic in temporal lobe epilepsy (TLE), possibly via anti-inflammatory actions. We studied effects of the mTOR inhibitor rapamycin and the anti-inflammatory compound curcumin-also reported to inhibit the mTOR pathway-on epileptogenesis and inflammation in an in vitro organotypic hippocampal-entorhinal cortex slice culture model.

Methods: Brain slices containing hippocampus and entorhinal cortex were obtained from 6-day-old rat pups and maintained in culture for up to 3 weeks. Rapamycin or curcumin was added to the culture medium from day 2 in vitro onward. Electrophysiological recordings revealed epileptiformlike activity that developed over 3 weeks.

Results: In week 3, spontaneous seizurelike events (SLEs) could be detected using whole cell recordings from CA1 principal neurons. The percentage of recorded CA1 neurons displaying SLEs was lower in curcumin-treated slice cultures compared to vehicle-treated slices (25.8% vs 72.5%), whereas rapamycin did not reduce SLE occurrence significantly (52%). Western blot for phosphorylated-S6 (pS6) and phosphorylated S6K confirmed that rapamycin inhibited the mTOR pathway, whereas curcumin only lowered pS6 expression at one phosphorylation site. Real-time quantitative polymerase chain reaction results indicated a trend toward lower expression of inflammatory markers IL-1β and IL-6 and transforming growth factor β after 3 weeks of treatment with rapamycin and curcumin compared to vehicle.

Significance: Our results show that curcumin suppresses SLEs in the combined hippocampal-entorhinal cortex slice culture model and suggest that its antiepileptogenic effects should be further investigated in experimental models of TLE.