The rodenticide tetramethylenedisulfotetramine (TETS) and the organophosphorus (OP) pesticide parathion are considered credible terrorist threat agents. Current medical countermeasures for acute TETS or OP intoxication can prevent mortality but do not sufficiently protect the CNS from persistent seizures and/or permanent injury. Therefore, new and more effective countermeasures must be developed to facilitate better medical treatment of civilians, first responders and military personnel following exposure to acutely toxic levels of TETS, parathion and similar chemical threat agents. The goals of the proposed research are to develop rodent models of TETS- and parathion-induced seizures and then use these models to identify potential therapeutic agents. We seek to identify agents that can protect against the development of seizures or treat seizures once they have begun and/or can prevent irreversible neuronal injury. We plan to evaluate a 2,3- benzodiazepine AMPA receptor antagonist and a soluble epoxide hydrolase inhibitor (sEHi). We have recently shown that AMPA receptor antagonists provide sustained seizure protection and are able to block seizures when administered at later times when there is refractoriness to diazepam, the benzodiazepine typically used to treat acute TETS and OP intoxication. We and others have data indicating that sEHi also exhibit anti- epileptic properties. Perhaps more important in light of recent evidence suggesting that the use of anti- inflammatory compounds in combination with standard antidote significantly decreases neuronal damage in acute OP intoxication, we have demonstrated that sEHi are also potent anti-inflammatory compounds. These observations suggest the potential for AMPA receptor antagonists and sEHi to significantly improve the clinical management of acute TETS and parathion intoxication by extending the therapeutic window and enhancing neuroprotection. To test this hypothesis, we will address two specific aims: (1) Develop rodent models of acute TETS and parathion intoxication;and 2) Determine whether AMPA receptor antagonist and/or sEHi are of therapeutic benefit in acute TETS or parathion intoxication when administered prior to or after exposure to the chemical threat agent. Endpoints that will be measured across all Aims include time to onset, frequency and duration of clonic and tonic seizures, EEG, histological measures of neuropathology and blood levels of TETS, AMPA receptor antagonist and sEHi. AMPA receptor antagonists and sEHi are currently undergoing human clinical trials and have demonstrated an excellent safety record;which will facilitate translation of positive findings in these rodent models to human studies. In summary, this project will develop rodent models of acute TETS and parathion intoxication that will be useful to the field beyond the proposed studies, and it will generate critical information on novel treatment approaches of practical value for two diverse classes of chemical threat agents.
The rodenticide tetramethylenedisulfotetramine (TETS) and the organophosphorus (OP) pesticide parathion are considered credible terrorist threat agents. Current medical countermeasures for acute TETS or OP intoxication can prevent mortality but do not sufficiently protect the CNS from persistent seizures and/or permanent injury. The goal of this research project is to test the hypothesis that AMPA receptor antagonists and/or inhibitors of soluble epoxide hydrolases will significantly improve outcome following exposure to acutely toxic levels of TETS and parathion by extending the therapeutic window for seizure protection and enhancing neuroprotection.
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