Inducible nitric oxide synthase inhibitor, 1400W, mitigates DFP-induced long-term neurotoxicity in the rat model

NEUROBIOLOGY OF DISEASE

卷:133

Review

Putra, Marson¹  Sharma, Shaunik¹  Gage, Meghan¹  Gasser, Grace³  Hinojo-Perez, Andy¹  Olson, Ashley¹  Gregory-Flores, Adriana¹  Puttachary, Sreekanth²  Wang, Chong⁴  Anantharam, Vellareddy³  Thippeswamy, Thimmasettappa¹ 

[1] Iowa State Univ, Coll Vet Med, Dept Biomed Sci, Ames, IA 50011 USA

[2] Oregon State Univ, Carlson Coll Vet Med, Dept Biomed Sci, Corvallis, OR 97331 USA

[3] PK Biosci, Ames, IA 50011 USA

[4] Iowa State Univ, Coll Vet Med, Dept Vet Diagnost & Prod Anim Med, Ames, IA 50011 USA

关键词: Neuroinflammation;    Video-EEG;    Neurodegeneration;    Spontaneous recurrent seizure;    Chemical nerve agent;   

DOI  :  10.1016/j.nbd.2019.03.031

来源: Elsevier

【 摘 要 】

Chemical nerve agents (CNA) are increasingly becoming a threat to both civilians and military personnel. CNA-induced acute effects on the nervous system have been known for some time and the long-term consequences are beginning to emerge. In this study, we used diisopropylfluorophosphate (DFP), a seizurogenic CNA to investigate the long-term impact of its acute exposure on the brain and its mitigation by an inducible nitric oxide synthase (iNOS) inhibitor, 1400W as a neuroprotectant in the rat model. Several experimental studies have demonstrated that DFP-induced seizures and/or status epilepticus (SE) causes permanent brain injury, even after the counter-measure medication (atropine, oxime, and diazepam). In the present study, DEP-induced SE caused a significant increase in iNOS and 3-nitrotyrosine (3-NT) at 24 h, 48 h, 7d, and persisted for a long-term (12 weeks post-exposure), which led to the hypothesis that iNOS is a potential therapeutic target in DFP-induced brain injury. To test the hypothesis, we administered 1400W (20 mg/kg, i.m.) or the vehicle twice daily for the first three days of post-exposure. 1400W significantly reduced DFP-induced iNOS and 3-NT upregulation in the hippocampus and piriform cortex, and the serum nitrite levels at 24 h post-exposure. 1400W also prevented DFP-induced mortality in < 24 h. The brain immunohistochemistry (IHC) at 7d post-exposure revealed a significant reduction in gliosis and neurodegeneration (NeuN + FJB positive cells) in the 1400W-treated group. 1400W, in contrast to the vehicle, caused a significant reduction in the epileptiform spiking and spontaneous recurrent seizures (SRS) during 12 weeks of continuous video-EEG study. IHC of brain sections from the same animals revealed a significant reduction in reactive gliosis (both microgliosis and astrogliosis) and neurodegeneration across various brain regions in the 1400W-treated group when compared to the vehicle -treated group. A multiplex assay from hippocampal lysates at 6 weeks post-exposure showed a significant increase in several key pro-inflammatory cytokines/chemokines such as IL-1 alpha, TNF alpha, IL-1 beta, IL-2, IL-6, IL-12, IL-17a, MCP -1, LIX, and Eotaxin, and a growth factor, VEGF in the vehicle-treated animals. 1400W significantly suppressed IL-1 alpha, TNF alpha, IL-2, IL-12, and MCP-1 levels. It also suppressed DFP-induced serum nitrite levels at 6 weeks post-exposure. In the Morris water maze, the vehicle -treated animals spent significantly less time in the target quadrant in a probe trial at 9d post-exposure compared to their time spent in the same quadrant 11 days previously (i.e., 2 days prior to DFP exposure). Such a difference was not observed in the 1400W and control groups. However, learning and short-term memory were unaffected when tested at 10-16d and 28-34d post-exposure. Accelerated rotarod, horizontal bar test, and the forced swim test revealed no significant changes between groups. Overall, the findings from this study suggest that 1400W may be considered as a potential therapeutic agent as a follow-on therapy for CNA exposure, after controlling the acute symptoms, to prevent mortality and some of the long-term neurotoxicity parameters such as epileptiform spiking, SRS, neurodegeneration, reactive gliosis in some brain regions, and certain key proinflammatory cytokines and chemokine.