Organophosphorus nerve agents (OP) are toxic chemicals that have been used by terrorists in military combat and against civilian populations. Current clinical post-exposure countermeasures against OP nerve agents are useful in preventing mortality, but are not sufficiently effective in protecting the CMS from seizures and permanent injury. Therefore, new and more effective countermeasures against chemical threats must be developed to facilitate better medical treatment of civilians and military personnel following exposure to OP. Recent studies have demonstrated the existence of neuronal injury, secondary to the stimulation of cholinergic pathways, which is associated with pro-inflammatory processes in the CMS during exposure to the nerve agents. The use of anti-inflammatory compounds, in combination with the current antidotal drugs, has been shown to decrease toxic symptoms and inflammation-induced brain damage. The objective of this study was to evaluate the therapeutic benefit of administration of neuregulin-1 (NRG-1), a neuroprotective, anti-inflammatory compound, alone or as a complement to the standard therapy against OP nerve agent poisoning. Recent work from our lab demonstrated NRG-1 reduced neuronal death in a rat focal ischemia model. The central hypothesis of this project is that NRG-1, alone or in combination with classical antidotal drugs, represents a novel, enhanced neuroprotective strategy that prevents non-AChE-mediated neuronal injury following exposure to OP with an extended therapeutic window. To test our hypothesis, we will employ the following set of specific aims: (1) To determine the prophylactic neuroprotective capacity of NRG-1 in OP-mediated neuronal injury; (2) To investigate whether co-administration of NRG-1 with classical antidotal drugs enhances neuroprotection from OP-mediated injury ; (3) To determine the post-exposure therapeutic window for NRG-1 in neuroprotection from OP-mediated injury and (4) To determine the feasibility of using in vitro models for screening neuregulin combinatorial therapies for neuroprotection against OP-induced neuronal injury. As a potential counterterrorism agent, NRG-1 represents a promising adjuvant therapy to the currently available antidotal treatments to ensure optimal treatment of OP nerve agent poisoning in humans. Therefore, NRG-1 represents a novel, potent neuroprotective strategy that has potential therapeutic value in treating individuals after acute exposure to neurotoxic compounds. [unreadable] [unreadable] [unreadable]