CREATING A MOUSE MODEL OF HYPERGLYCINEMIC NEUROBIOLOGY

非酮性高甘氨酸血症（NKH）是一种先天性代谢缺陷， 由于甘氨酸裂解系统（GCS）的缺陷或功能障碍， 在肝、肾、脑和胎盘中表达的酶复合物 线粒体受影响的个人发展嗜睡，呼吸暂停，肌阵挛 在生命的最初几天。那些在新生儿期存活下来的人 顽固性癫痫和严重的智力迟钝功能障碍 GCS导致血浆和所有身体组织中甘氨酸积聚 包括大脑。临床表型被认为是由于 甘氨酸作为神经递质的作用：在脑干中具有抑制作用， 当作用于士的宁敏感的甘氨酸受体时，作用于脊髓; 当作用于NMDA受体通道时，在前脑中具有兴奋性 复杂. GCS在调节CNS甘氨酸浓度中的作用是 未知的是脑甘氨酸浓度升高对 抑制性甘氨酸受体和NMDA受体水平，亚单位 组成和分布。NKH的动物模型将有助于 对这种疾病过程的病理生理学的全面评价 并提供对甘氨酸和GCS的正常生物学的见解， 该系统在其他疾病中的潜在致病作用， 特发性癫痫和缺氧缺血性损伤。 这个项目的总体目标是 项目是建立一个小鼠模型的NKH和表征的NKH 小鼠的表型、生化、神经解剖和 神经化学 小鼠将通过靶向破坏 小鼠甘氨酸脱羧酶基因的同源重组 胚胎干细胞甘氨酸的数量和分布 脱羧酶mRNA和蛋白质将通过原位杂交测定。 杂交、北方印迹分析、免疫细胞化学和Western 印迹分析脑和肝脏中GCS活性的定量以及 将进行血浆、CSF和组织甘氨酸浓度测定。 表型参数包括存活、生长、进食、运动， 活动水平生育能力和脑电图分析的 甘氨酸浓度升高对脑发育的影响， 病理学将通过胚胎组织的尼氏染色和苏木精染色来评估。 和出生后的老鼠大脑。的分布和亚基组成 NMDA和其他谷氨酸受体将通过特异性测定来确定。 抗体的

Nonketotic hyperglycinemia (NKH) is an inborn error of metabolism caused by deficiency or dysfunction of the glycine cleavage system (GCS), an enzyme complex expressed in liver, kidney, brain, and placental mitochondria. Affected individuals develop lethargy, apnea, and myoclonus in the first days of life. Those surviving the neonatal period develop intractable seizures and profound mental retardation. Dysfunction of the GCS leads to accumulation of glycine in plasma and all body tissues including the brain. The clinical phenotype is thought to result from glycine's role as a neurotransmitter: inhibitory in the brain stem and spinal cord when acting upon the strychnine-sensitive glycine receptor; excitatory in the forebrain when acting upon the NMDA-receptor channel complex. The role of the GCS in modulating CNS glycine concentrations is unknown as are the effects of elevated brain glycine concentration upon the inhibitory glycine receptor and upon NMDA receptor levels, subunit composition, and distribution. An animal model of NKH will facilitate a comprehensive appreciation of the pathophysiology of this disease process and provide insight into the normal biology of glycine and the GCS and potentially the pathogenic role of this system in other disorders such as idiopathic epilepsy and hypoxic-ischemic injury. The overall goal of this project is to create a mouse model for NKH and to characterize the NKH mouse phenotypically, biochemically, neuroanatomically and neurochemically. The mouse will be made by targeted disruption of the murine glycine decarboxylase gene using homologous recombination in embryonic stem cells. The quantity and distribution of glycine decarboxylase mRNA and protein will be determined by in situ hybridization, Northern blot analysis, immunocytochemistry and Western blot analysis. Quantitation of GCS activity in the brain and liver and of plasma, CSF, and tissue glycine concentrations will be performed. Phenotypic parameters include survival, growth, feeding, movements, activity level, fertility, and electroencephalographic analysis. The effect of elevated glycine concentrations upon brain development and pathology will be assessed by Nissl and hematoxylin staining of embryonic and postnatal mouse brains. The distribution and subunit composition of NMDA and other glutamate receptors will be determined by specific antibodies.