Abstracts

Rationale: Various reactive oxygen species (ROS) after epileptic seizure has been related to neuronal death and subsequent epileptogenesis. However, the role of superoxide anion, one of the powerful ROS, in the seizure-induced cell death has been remained unclear. We investigated the role of superoxide anion in seizure-induced cell death and the possible mechanism of neuronal protection underlying lamotrigine treatment in regard to superoxide dismutase (SOD) 1, a potent inhibitor of superoxide anion.Methods: Adult male C57BL/6J mice were given injections of pilocarpine 30 min after scopolamine treatment. Seizures were terminated by diazepam injection after status epilepticus (SE) at various time points. Hippocampal neuronal death was assessed by cresyl-violet and TUNEL staining. The hippocampal superoxide anion was assessed using in situ detection of oxidized hydroethidine (HEt); administered intravenously after SE. SOD1 level was analyzed by both Western blot and semi-quantitative immunofluorescent staining in different subfields of hippocampus. Various doses of lamotrigine (10, 30, 60 mg/kg, i.p., dissolved in 20% beta-cyclodextrin) were administrated. Results: Superoxide anion significantly increased after pilocarpine-induced SE, compared to vehicle, which were in concordance with increased cell death by TUNEL and cresyl-violet staining. The production of superoxide anion in response to SE was least in dentate gyrus, which was reversely in agreement with maximal SOD1 increase in the same subfield. Treatment of lamotrigine significantly decreased the production of superoxide anion after SE, compared to vehicle. In addition, hippocampal neuronal death was significantly attenuated by lamotrigine treatment in dose dependent manner. SOD1 also increased by lamotrigine treatment after SE, and the effect was greatest in CA3 subfield, in which SOD1 was significantly decreased without lamotrigine treatment. Conclusions: Increased production of superoxide anion after SE may contribute hippocampal neuronal death after seizure. Lamotrigine may inhibit superoxide anion-related cell death through increase of SOD1 in the hippocampus after SE.