CREATING A MOUSE MODEL OF HYPERGLYCINEMIC NEUROBIOLOGY

非酮症性高血糖(NKH)是一种先天的代谢错误 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体 线粒体。患者会出现嗜睡、呼吸暂停和肌阵挛。 在生命的最初几天。那些在新生儿期存活下来的人会发展成 顽固性癫痫发作和严重的智力低下。脑部功能障碍 GCS导致甘氨酸在血浆和全身组织中蓄积 包括大脑。临床表型被认为是由 甘氨酸作为神经递质的作用：在脑干和 脊髓作用于士的宁敏感的甘氨酸受体； 作用于NMDA受体通道时前脑的兴奋性 很复杂。GCS在调节中枢神经系统甘氨酸浓度中的作用是 目前尚不清楚大脑甘氨酸浓度升高对脑血管疾病的影响 抑制甘氨酸受体及其对NMDA受体亚基水平的影响 组成和分配。NKH的动物模型将促进 综合评价本病的病理生理学过程 并提供对甘氨酸和GCS的正常生物学的洞察以及 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 项目是为NKH创建一个鼠标模型，并描述NKH的特征 小鼠的表型，生化，神经解剖学和 神经化学方面。鼠标将通过有针对性的扰乱 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 脱羧酶基因和蛋白的原位检测 杂交、Northern印迹分析、免疫细胞化学和Western 印迹分析。脑组织和肝脏中GCS活性的定量测定 将进行血浆、脑脊液和组织甘氨酸浓度测定。 表型参数包括存活、生长、取食、运动、 活动水平、生育能力和脑电分析。这个 甘氨酸浓度升高对脑发育和脑功能的影响 病理将通过尼氏染色和苏木素染色进行评估。 以及出生后的小鼠大脑。的分布和亚基组成 NMDA和其他谷氨酸受体将通过特定的 抗体。

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.