Anesthesia-Induced Developmental Neuroapoptosis in non-Human Primates

描述（由申请人提供）：这是一份经过修订的竞争性RO1申请，要求支持有关麻醉药物在发育中的猴子大脑中触发凋亡性神经变性的能力的研究。在最近的一系列研究中，申请人已经证明，在突触发生的发育时期，幼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，会引发发育中的大脑中广泛的神经凋亡。在大鼠和小鼠中，突触发生期，也被称为大脑生长突增期，发生在出生后的头两周，但在人类中，从妊娠中期开始，一直持续到出生后大约3年。发育性神经细胞凋亡机制的核心是这样一个生物学事实：如果发育中的大脑神经元不能建立适当的突触连接，它们就会自杀。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，这就会破坏突触发生过程，足以导致大量神经元自杀。这些发现在麻醉领域具有潜在的关注，因为大多数（如果不是全部的话）全麻药具有NMDA拮抗剂或gabamiame特性，当使用浓度或剂量足以使患者失去知觉或对疼痛没有知觉时，它们会深刻抑制神经元活动。虽然麻醉诱导的发育性神经细胞凋亡（AIDNA）在啮齿动物大脑中是一种很容易证明的现象，但关于其他物种的易感性的信息有限。在非常有限的试点实验中，我们观察到胎儿猴似乎对乙醇或麻醉药物的凋亡特性很敏感。为了进一步评估灵长类动物大脑对AIDNA损伤的易感性，我们将在松鼠猴的大脑生长突增期（主要发生在产前（妊娠的最后两个月））对松鼠猴进行麻醉。在目标#1中，我们将在大脑发育井喷期的三个时间点之一，将子宫内的猴子胎儿暴露在三重麻醉鸡尾酒中（异氟烷，氧化亚氮，咪达唑仑），并研究大脑中AIDNA的证据。在目标#2中，在敏感性达到峰值的年龄（在目标#1实验中确定），我们将使松鼠猴胎儿暴露于单一麻醉剂（异氟烷或异丙酚），或双重组合（异氟烷+氧化亚氮，或异丙酚+氧化亚氮），以帮助阐明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.