Anesthesia-Induced Developmental Neuroapoptosis in non-Human Primates

描述（由申请方提供）：这是一项修订后的竞争性RO1申请，请求支持与麻醉药物在发育中猴脑中引发凋亡性神经变性的能力相关的研究。在一系列最近的研究中，申请人已经表明，在突触发生的发育期期间，将幼年大鼠或小鼠短暂暴露于某些类别的药物，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。突触发生期，也称为大脑生长突增期，在大鼠和小鼠中发生在出生后的前两周，但在人类中，从妊娠中期开始，一直持续到出生后约3年。发育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如果不能建立适当的突触连接，就会被编程杀死自己。虽然正常情况下，只有一小部分神经元会因突触发生错误而自杀，但我们在啮齿动物实验中的发现表明，如果神经元活动被异常抑制仅几个小时，这会破坏突触发生过程，足以导致大量神经元自杀。这些发现在麻醉背景下具有潜在的问题，因为大多数（如果不是全部）全身麻醉药具有NMDA拮抗剂或GABA模拟物特性，并且当以足以使患者无意识和对疼痛无感觉的浓度或剂量使用时，它们深刻地抑制神经元活动。虽然麻醉诱导的发育性神经细胞凋亡（AIDNA）是一个很容易证明的现象，在啮齿动物的大脑，只有有限的信息是有关其他物种的易感性。在非常有限的初步实验中，我们观察到，胎儿猴似乎对乙醇或麻醉药物的致癫痫特性敏感。为了进一步评估发育中的灵长类动物大脑对AIDNA损伤的敏感性，我们将在大脑生长突增期期间将松鼠猴暴露于麻醉，这在该物种中主要发生在产前（妊娠的最后两个三个月）。在目标#1中，我们将在脑生长突增期的三个时间点之一，将子宫内的猴胎暴露于三重麻醉剂混合物（异氟烷、一氧化二氮、咪达唑仑），并研究脑中是否存在AIDNA的证据。在目标#2中，在敏感性峰值年龄（如目标#1实验中确定的），我们将使松鼠猴胎仔暴露于单独的麻醉剂（异氟烷或丙泊酚）或双重组合（异氟烷+一氧化二氮或丙泊酚+一氧化二氮），以帮助澄清每种药物或药物组合造成的风险程度。

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.