Abstracts

Rationale: Chemical nerve agent (CNA) exposure at high concentrations leads to cholinergic toxidrome and status epilepticus (SE). SE increases the production of ROS/RNS, neuroinflammation, and neurodegeneration (PMID: 29197620). 1400W is a novel small molecule and an inhibitor of iNOS and has been shown to effectively reduce ROS/RNS generation. In this study, we investigated the early effects of 1400W, as a disease modifying agent in the rat DFP model.

Methods: Sprague Dawley rats (8 weeks) were administered with DFP (4 mg/kg, s.c.) or vehicle immediately followed by atropine sulfate (2 mg/kg, i.m.) and 2-PAM (25 mg/kg, i.m.) to control the peripheral effects of AChE inhibition. Telemetry devices were implanted prior to DFP exposure to monitor EEG and continuous video-EEG was acquired for 15 days. Following DFP injection, behavioral SE severity was scored on a modified Racine for 60 minutes. Midazolam (MDZ, 3 mg/kg, i.m.) was administered 1 hr post-DFP to limit mortality. Animals were then randomly allotted to experimental groups with equal number of male and females (n=5/sex) with matched SE severity, and treated with vehicle or 1400W (10 mg/kg or 15 mg/kg for 7 or 14 days). All animals were perfused with 4% paraformaldehyde at 8 or 15 days post-DFP. Brains were processed for immunohistochemistry (neurodegeneration and gliosis), and the serum was used for nitrooxidative and cytokine assays. Statistical differences were calculated using unpaired t-test, one-way or two-way Analysis of Variance (ANOVA) followed by Tukey’s post-hoc test, or a non-parametric Mann Whitney or Kruskal Wallis post-hoc test. Data was presented as mean ± SEM.

Results: No significant differences in SE severity score were observed between males and females following DFP exposure. 1400W treatment (10 mg/kg for 8 days and 15 mg/kg for 8 days) significantly reduced the number of microglial and astroglial cells compared to DFP + vehicle in different regions of the brain. 1400W treatment (10 mg/kg for 8 days and 15 mg/kg for 8 days) showed a promising trend in reducing the number of FJB positive cells in different regions of the brain. There were no significant differences in the epileptiform spike rate and seizures per day between the any treatment groups in mixed sex cohorts and between males and females. 1400W significantly reduced nitrooxidative markers (nitrite, ROS, GSH:GSSG) and proinflammatory cytokines/chemokine in serum (IL10, TNFα, IL-6, and MCP1). _x000D_
Conclusions: 1400W treatment significantly reduced gliosis, nitrooxidative stress, and key pro-inflammatory cytokines/chemokines. The 15 mg/kg for two weeks, rather than for a week, was largely effective, however, 10 mg/kg for a shorter period had limited benefits.

Funding: NIH (U01NS117284, CounterACT program)