Age and sex effects on nerve agent damage to the brain and antidotal therapies

神经毒剂梭曼、沙林和VX在化学上与有机磷化合物(OP)有关，但 比有机磷杀虫剂毒性大得多。它们的大多数急性毒性都是由于其不可逆转的抑制 乙酰胆碱酯酶(AChE)，使内源性神经递质乙酰胆碱失活的酶。 针对OP中毒的现有治疗方法的局限性是公认的，而且更有效的解毒剂 必须被开发出来。在这个项目中，我们将检验一个中心假设，即解毒剂疗法 加兰他明，一种目前被批准用于治疗阿尔茨海默病(AD)的药物，无论是否有 M受体拮抗剂阿托品可对抗神经毒剂对豚鼠的即刻和延迟性毒性 不同日龄的两性猪。我们有证据表明加兰他明和阿托品的结合， 在急性暴露于致命剂量的神经毒剂或杀虫剂之前或之后有效地给药 并能安全地中和它们对青春期雄性豚鼠的毒性。尽管人们对他们的研究知之甚少 神经生理学方面，豚鼠被认为是预测非灵长类动物模型有效性的最佳模型 人类OP中毒的解毒剂。在目标1中，我们将确定年龄和性别依赖 梭曼、沙林和VX的急性毒性，并优化由加兰他明组成的解毒治疗， 或不含阿托品，适用于三岁的雄性和雌性豚鼠，即新生、青春期和成年。这个 优化治疗对预防神经毒剂即时和/或迟发性毒性作用的有效性 然后将对神经功能和大脑完整性进行检查。在目标2中，我们将调查 突触功能改变与时间关系的治疗(电生理学研究) 神经细胞形态计量学(无创性MRI研究)和神经元存活率(组织病理学分析)的变化 暴露在神经毒剂下的豚鼠大脑。通过与USAMRICD研究人员的合作，我们 将进一步检验解毒治疗维持正常横隔膜和认知功能的效果 不同年龄神经毒剂对不同性别豚鼠行为的影响。在目标3中，我们将推导出 后续临床研究所需的药代动力学参数 为人类所用。仍然在这个目标范围内，我们将确定加兰他明诱导的可逆抑制的相关性。 疼痛在不同的隔间对治疗效果的影响。我们将特别强调 认为加兰他明作为一种选择性的血液AChE抑制剂，将有助于清除 神经毒剂。在目标4中，我们将在整个动物水平上确定新的分子机制 有助于神经毒剂的毒性和加兰他明/阿托品的有效性。这些研究的结果 研究将是深远的，因为它们将为加快安全解毒剂的开发提供基础。 在暴露于神经毒剂的情况下，供急救人员和普通民众使用。

The nerve agents soman, sarin and VX are organophosphorus compounds (OPs) chemically related to, but far more toxic than OP insecticides. Most of their acute toxicity results from the irreversible inhibition of acetylcholinesterase (AChE), the enzyme that inactivates the endogenous neurotransmitter acetylcholine. The limitations of available therapies against OP poisoning are well recognized, and more effective antidotes have to be developed. In this project, we will test the central hypothesis that an antidotal therapy composed of galantamine, a drug presently approved for treatment of Alzheimer's disease (AD), with or without the muscarinic antagonist atropine can counteract the immediate and delayed toxicity of nerve agents in guinea pigs of both sexes at different ages. We have evidence that the combination of galantamine and atropine, administered before or after an acute exposure to lethal doses of nerve agents or insecticides, effectively and safely counteracts their toxicity in peripubertal male guinea pigs. Although little is known regarding their neurophysiology, guinea pigs are considered the best non-primate model to predict the effectiveness of antidotes against OP intoxication in humans. In aim 1, we will determine the age and sex dependencies of the acute toxicity of soman, sarin, and VX, and optimize the antidotal therapy consisting of galantamine, with or without atropine, for male and female guinea pigs at three ages, i.e.neonatal, peripubertal, and adult. The effectiveness of the optimized therapy to prevent immediate and/or delayed toxic effects of the nerve agents will then be examined in neuronal function and brain integrity. In aim 2, we will investigate the effects of the therapy on the temporal relationship between changes in synaptic function (electrophysiological studies) and alterations in morphometry (non-invasive MRI studies) and neuronal viability (histopathological analysis) in the brains of guinea pigs acutely exposed to nerve agents. In collaboration with USAMRICD researchers, we will further examine the effectiveness of the antidotal therapy to maintain normal diaphragm and cognitive behavior in guinea pigs of both sexes exposed to nerve agents at different ages. In aim 3, we will derive pharmacokinetic parameters needed for subsequent clinical studies of the safety of the proposed therapy for human use. Still within this aim, we will determine the relevance of galantamine-induced reversible inhibition of AChE in distinct compartments to the effectiveness of the therapy. Particular emphasis will be given to the notion that galantamine, acting as a selective inhibitor of blood AChE, will facilitate the clearance of the nerve agents. In aim 4, we will determine, at whole animal level, how novel molecular mechanisms contribute to the toxicity of nerve agents and the effectiveness of galantamine/atropine. The results of these studies will be far reaching as they will provide the foundation to expedite the development of safe antidotes to be used by the first responders and the general population in the event of an exposure to nerve agents.