Abstracts

Rationale: Zinc is released from mossy fiber axons in the hippocampal CA3-hilar region. We are interested in a specific subtype of sodium channel Na_v1.5 which is inhibited by zinc and seen in certain areas of the brain which are in close proximity to zinc rich terminals. Methods: We used pilocarpine induced epileptic models of rats to study the role of zinc in the newly sprouted recurrent mossy fibers. The appearance of recurrent mossy fibers in hippocampal slices from rats was confirmed by Timm's staining and also using a fluorescent marker for zinc. Immunofluorescent labeling will be employed to study expression of Na_v1.5 channels in the hippocampal region.Results: Using Newport Green, an extracellular fluorescent indicator for zinc we were able to show increase in fluorescence in the molecular layer of the dentate gyrus upon high frequency electrical stimulation of the hilar region which corresponds to release of zinc from recurrent mossy fiber terminals. Our preliminary experiments using zinc chelators show that zinc inhibits excitatory activity in the brain.Conclusions: We attribute one of the mechanisms of inhibition of epileptiform activity in the pilocarpine induced chronic epilepsy model to the interaction between zinc and Na_v1.5 voltage gated channels.