Oxidative Stress Contributes to Status Epilepticus Associated Mortality

Abstract

Status epilepticus is a common manifestation of nerve agent toxicity and represents a serious medical emergency with high rates of mortality and neurologic injury in those that survive. The aim of the current study was to determine if targeting oxidative stress with the catalytic antioxidant, AEOL10150, would reduce pilocarpine-induced mortality and attenuate neuronal death and neuroinflammation. We found that treatment with AEOL10150 in conjunction with scopolamine and diazepam following pilocarpine-induced SE was able to significantly reduce mortality compared to treatment with just scopolamine and diazepam. Mortality was further reduced when AEOL10150 was used in conjunction with atropine and diazepam which is considered the standard of care for nerve agent exposures. Both treatment paradigms offered significant protection against SE-induced oxidative stress. Additionally, treatment with scopolamine, AEOL10150 and diazepam attenuated SE-induced neuronal loss and neuroinflammation. Taken together, the data suggest that pharmacological targeting of oxidative stress can improve survival and attenuate secondary neurological damage following SE induced by the nerve agent surrogate pilocarpine.

Keywords: Epilepsy; Glutathione; Nerve agent toxicity; Pilocarpine.

Fig. 1

Oxidative stress in rats treated with pilocarpine after 24 and 48 h. a GSH, b GSSG levels, c GSH/GSSG ratio and d 3NT/Tyr ratio were measured in the hippocampi of saline and pilocarpine treated rats at 24 and 48 h. ***p < 0.001 compared to saline injected control

Fig. 2

Effect of AEOL10150 on pilocarpine-induced SE survival rates. All rats received scopolamine (1 mg/kg), pilocarpine (340 mg/ kg) and diazepam (10 mg/kg). Treatment with AEOL10150 (5 mg/kg) starting 60 min after SE and continuing every 4 h thereafter significantly improved SE-related mortality up to 48 h after SE. *p < 0.05

Fig. 3

Identification of therapeutic window of AEOL10150 when given in conjunction with scopolamine, pilocarpine and diazepam. a GSH, b GSSG, c GSH/GSSG and d 3NT in the hippocampus of rats 24 h after scopolamine, pilocarpine and diazepam with or without AEOL10150 (5 mg/kg) when given 30 min prior to pilocarpine (pretreatment) or 90 min after pilocarpine (post-treatment). *p < 0.05 vs. control, #p < 0.05 vs. pilocarpine treatment

Fig. 4

Indices of oxidative stress in rats treated with pilocarpine, atropine, diazepam and AEOL10150. a GSH, b GSSG, c GSH/GSSG ratio and d 3-NT/tyrosine in the hippocampus of rats 24 h after either pilocarpine alone w/o atropine (atr) and diazepam or in the presence of AEOL 10150 (5 mg/kg) starting 60 min after SE and continuing every 4 h. a p < 0.05 versus control, b p < 0.05 versus pilocarpine-treated rats, c p < 0.05 versus pilocarpine + atropine + diazepam treated rats

Fig. 5

Neuronal loss and microgliosis in hippocampus of rats treated with scopolamine, pilocarpine, diazepam and with or without AEOL10150 (5 mg/kg) starting 90 min after SE and continuing every 4 h. Representative images of FJB staining in a CA3 and b Hilus. Representative images of IBA1 staining in c CA3 and d Hilus. e Quantification of FJB staining indicative of neuronal loss in the f CA3 region and hilar region of the hippocampus. g Quantification of IBA1 staining indicative of microgliosis in the CA3 and h hilus of the hippocampus of rats 24 h after SE. *p < 0.05 vs. control, #p < 0.05 vs. pilocarpine treatment