Developmental neurotoxicity of sarin and soman in guinea pigs

描述(申请人提供)：发育中的哺乳动物中枢神经系统(CNS)对有机磷(OP)神经毒剂的敏感性以及通常用于治疗急性OP中毒的解毒剂如阿托品和解磷定在孕妇和发育中的胎儿中的安全性迄今尚不清楚。因此，在1995年东京地铁沙林恐怖袭击期间，孕妇在出现轻微的OP中毒迹象后寻求医疗救治，没有得到治疗。最近关于沙林在禽类模型中的神经行为致畸作用的报道，突显了研究OP神经毒剂的发育神经毒性的紧迫性。近年来，加兰他明，一种目前被批准用于治疗阿尔茨海默病的药物，在新生、青春期前和成年豚鼠中作为急性OP中毒的有效解毒剂出现。加兰他明的治疗也被证明可以抵消青春期前豚鼠单次暴露于0.6-1.0xLD50梭曼几个月后出现的认知障碍和焦虑样行为。因此，本项目旨在验证一个中心假设，即发育中的哺乳动物中枢神经系统对神经毒剂沙林和梭曼极其敏感，加兰他明或阿托品将是对抗这些毒剂的发育神经毒性的有效医学对策。豚鼠将成为首选的动物模型，因为：(I)豚鼠的大脑发育与人类和非人类灵长类动物非常相似，(Ii)与人类一样，豚鼠的循环羧酸酯酶水平较低--这种酶能在代谢过程中使OP化合物失活。该项目的近期目标是：(I)确定产前暴露于梭曼或沙林对豚鼠神经行为以及大脑功能、结构和代谢完整性的影响，以及(Ii)评估 加兰他明或阿托品的安全性和有效性，剂量与人类使用相适应，以对抗神经毒剂的发育毒性。怀孕的豚鼠将在关键的妊娠期(GD50-52)接受皮下注射赋形剂或一定剂量(0.6x或1.0xLD50)的梭曼或沙林。随后(1或24小时后)，母猪接受生理盐水(0.5ml/kg，im)或临床相关剂量的加兰他明(8 mg/kg，im)或阿托品(0.5 mg/kg，im)治疗。在出生后35-40天(青春期前)和120-125天(青春期)，将分析动物的认知和情感行为。为了检查出生前接触神经毒剂对大脑电活动的影响，在行为测试之前将远程监测脑电活动。磁共振成像和光谱学将被用来识别大脑结构和新陈代谢的偏差。这些转化性、多学科研究的结果将产生深远影响，因为它们将为推动旨在确定安全有效的治疗战略的研究奠定必要的基础，以便在发生沙林和梭曼恐怖袭击时甚至治疗人口中最敏感的部分。 与公共卫生相关：该项目的首要目标是为评估神经毒剂梭曼和沙林的发育毒性和鉴定先导化合物提供基本和及时的信息，以充分治疗因产前暴露于这些毒剂而引起的神经病理。

DESCRIPTION (provided by applicant): The sensitivity of the developing mammalian central nervous system (CNS) to organophosphorus (OP) nerve agents and the safety of antidotes such as atropine and pralidoxime, commonly used against acute OP toxicity, in pregnant women and the developing fetuses are hitherto unknown. Thus, during the 1995 terrorist attack with sarin in the Tokyo subway, pregnant women who sought medical attention after presenting mild signs of OP intoxication received no therapeutic treatment. The urgency of studies to investigate the developmental neurotoxicity of OP nerve agents is underscored by the recent report of the neurobehavioral teratogenicity of sarin in an avian model. In recent years, galantamine, a drug currently approved to treat Alzheimer's disease, emerged as an effective antidote against acute OP poisoning in neonatal, prepubertal, and adult guinea pigs. Treatment with galantamine was also shown to counteract the cognitive deficits and anxiety-like behavior seen months after a single exposure of prepubertal guinea pigs to 0.6-1.0xLD50 soman. The present project is, therefore, aimed at testing the central hypothesis that the developing mammalian CNS is exquisitely sensitive to the nerve agents sarin and soman and that galantamine or atropine will be effective medical countermeasures against the developmental neurotoxicity of these agents. The guinea pig will be the animal model of choice because: (i) brain development of guinea pigs closely resembles that of humans and non-human primates and (ii) like humans, guinea pigs have low levels of circulating carboxylesterases - the enzymes that metabolically inactivate OP compounds. The immediate goals of this project are: (i) to identify the effects of a prenatal exposure to soman or sarin on neurobehavior as well as functional, structural, and metabolic integrity of the brain of guinea pigs, and (ii) to assess the safety and effectiveness of galantamine or atropine, at doses that are compatible with human use, to counter the developmental toxicity of the nerve agents. Pregnant guinea pigs will receive, at a critical gestational period (GD 50-52), a subcutaneous injection of vehicle or a given dose (0.6x or 1.0xLD50) of soman or sarin. Subsequently (1 or 24 h later), the sows will be treated with saline (0.5 ml/kg, im) or a clinically relevant dose of galantamine (8 mg/kg, im) o atropine (0.5 mg/kg, im). On postnatal days 35-40 (prepuberty) and 120-125 (young adulthood), cognitive and emotional behavior of the animals will be analyzed. To examine the effects of the prenatal exposure to the nerve agents on electrical brain activity, electroencephalographic activity will be telemetrically monitored prior to the behavioral tests. Magnetic resonance imaging and spectroscopy will be used to identify deviations in brain structure and metabolism. The results of these translational, multidisciplinary studies will be far reaching as they will laythe groundwork necessary to advance research aimed at identifying safe and effective therapeutic strategies to treat even the most sensitive sector of the population in the event of a terrorist attack with sarin and soman. PUBLIC HEALTH RELEVANCE: The overarching goal of this project is to provide fundamental and timely input for assessment of the developmental toxicity of the nerve agents soman and sarin and identification of lead compounds for adequate treatment of neuropathologies that result from prenatal exposure to these agents.