Anesthesia-Induced Developmental Neuroapoptosis in non-Human Primates

描述(由申请人提供)：这是一份修订后的竞争RO1申请，请求支持与麻醉药引发发育中的猴子大脑中的凋亡性神经变性有关的研究。在最近的一系列研究中，申请者表明，在突触形成的发育期，婴儿大鼠或小鼠短暂地接触某些类别的药物，包括NMDA谷氨酸拮抗剂、GABAA激动剂或乙醇，会在发育中的大脑中引发广泛的神经细胞凋亡。大鼠和小鼠的突触发育期，也被称为脑生长爆发期，发生在出生后的头两周，但在人类，从妊娠中期开始，一直持续到出生后大约3年。发育中的神经细胞凋亡机制的核心是一个生物学事实，即发育中的大脑中的神经元被编程，如果它们不能建立适当的突触连接，就会自杀。虽然正常情况下，只有一小部分神经元因突触发生故障而自杀，但我们从啮齿动物实验中的发现表明，如果神经元活动受到异常抑制，只有几个小时，这就会扰乱突触发生过程，足以导致大量神经元自杀。这些发现在麻醉情况下是潜在的问题，因为大多数(如果不是全部)全麻药都具有NMDA拮抗剂或GABA仿效特性，当使用的浓度或剂量足以使患者昏迷和对疼痛失去知觉时，它们会严重抑制神经元活动。虽然麻醉诱导的发育性神经细胞凋亡(AIDNA)是一种在啮齿动物脑中很容易被证明的现象，但关于其他物种的易感性的信息有限。在非常有限的先导实验中，我们观察到胚胎猴子似乎对乙醇或麻醉药的致细胞凋亡特性敏感。为了进一步评估发育中的灵长类动物大脑对AIDNA损伤的易感性，我们将在脑生长突发期将松鼠猴子置于麻醉下，这一时期在这种物种中主要发生在产前(怀孕最后两个月)。在目标1中，我们将在大脑生长突发期的三个时间点之一将子宫中的猴子胎儿暴露于三种麻醉剂鸡尾酒(异氟烷、一氧化二氮、咪达唑仑)中，并研究大脑以寻找AIDNA的证据。在目标2中，在最敏感的年龄(在目标1实验中确定的)，我们将松鼠胚胎暴露于单独的麻醉剂(异氟烷或异丙酚)，或双重组合(异氟烷+一氧化二氮，或异丙酚+一氧化二氮)，以帮助澄清每个药剂或药剂组合所造成的风险程度。

DESCRIPTION (provided by applicant): This is a revised competing RO1 application requesting support for studies pertaining to the ability of anesthetic drugs to trigger apoptotic neurodegeneration in the developing monkey brain. In a series of recent studies, the applicants have shown that brief exposure of infant rats or mice to certain classes of drugs, including NMDA glutamate antagonists, GABAA agonists or ethanol, during the developmental period of synaptogenesis, triggers widespread neuroapoptosis in the developing brain. The period of synaptogenesis, also known as the brain growth spurt period, in rats and mice occurs during the first two weeks of postnatal life, but in humans, begins in mid-gestation and extends until approximately 3 years after birth. At the heart of the developmental neuroapoptosis mechanism is the biological fact that neurons in the developing brain are programmed to kill themselves if they fail to make appropriate synaptic connections. Although normally, only a small percentage of neurons commit suicide due to faulty synaptogenesis, our findings from rodent experiments suggest that if neuronal activity is abnormally suppressed for a period of only several hours this disrupts the synaptogenesis process sufficiently to cause large numbers of neurons to commit suicide. These findings are of potential concern in an anesthesia context because most, if not all, general anesthetics have either NMDA antagonist or GABAmimetic properties, and when used in concentrations or doses sufficient to render patients unconscious and insentient to pain, they profoundly suppress neuronal activity. While anesthesia-induced developmental neuroapoptosis (AIDNA) is a readily demonstrable phenomenon in rodent brain, only limited information is available pertaining to susceptibility of other species. In very limited pilot experiments we have observed that fetal monkeys appear to be sensitive to the apoptogenic properties of either ethanol or anesthetic drugs. To further evaluate susceptibility of the developing primate brain to AIDNA injury, we will expose squirrel monkeys to anesthesia during the brain growth spurt period, which in this species occurs primarily prenatally (last two trimesters of gestation). In Aim #1, we will expose monkey fetuses in utero to a triple anesthetic cocktail (isoflurane, nitrous oxide, midazolam) at one of three time points during the brain growth spurt period, and study the brains for evidence of AIDNA. In Aim #2, at the age of peak sensitivity (as determined in Aim #1 experiments), we will expose squirrel monkey fetuses to individual anesthetic agents (isoflurane or propofol), or to double combinations (isoflurane + nitrous oxide, or propofol + nitrous oxide), to help clarify the degree of risk posed by each agent or combination of agents.