IGF I THERAPY IN NEONATAL HYPOXIC ISCHEMIC BRAIN INJURY

IGF I 治疗新生儿缺氧缺血性脑损伤

• 批准号: 2445843
• 负责人: Wei-Hua Lee
• 金额: $ 10.32万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 2000-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2445843
• 关键词: binding proteins; brain disorder chemotherapy; brain injury; brain metabolism; cerebral ischemia /hypoxia; chemoprevention; developmental neurobiology; gene expression; gene therapy; growth factor receptors; immunocytochemistry; in situ hybridization; insulinlike growth factor; laboratory rat; neuroprotectants; newborn animals; nonhuman therapy evaluation; recombinant proteins; transfection; transfection /expression vector

Cerebral hypoxia-ischemia remains a leading cause of severe brain damage in newborns. The molecular mechanisms of the neuronal injury and subsequent repair processes are not well understood but may involve persistent disruption of cellular energy homeostasis, as evidenced by alterations in oxidative phosphorylation, nutrient uptake and utilization. Insulin-like growth factor I (IGF-I) is an anabolic pleiotrophic factor required by all cell types in the developing brain for optimal proliferation, differentiation, and survival. Soon after hypoxic-ischemic insult to newborn rat brain, IGF-I gene expression is decreased in vulnerable neurons and is activated in reactive astrocytes only after 2-3 days. Intraventricular infusion of IGF-I two hours following the hypoxic- ischemic insult reduces the neuronal loss in both the adult rat and the late gestation fetal lamb. The mechanism of this IGF-I mediated neuroprotection, however, is not understood. We hypothesize that IGF-I prevents impending neuronal injury during the early post-ischemic phase by regulating cellular energy metabolism. The specific aims of this proposal are: 1) to examine both the expression and the cellular specificity of an exogenous IGF-I gene delivered by virus vectors; 2) to determine the extent to which IGF-I can regulate certain aspects of normal rat brain cellular metabolism, such as substrate uptake, protein synthesis and neuronal activity; and 3) to determine whether hypoxia-ischemia-induced neuronal damage can be ~meliorated as a result of enhanced IGF-I gene expression. Hence, we will first study the functional role of IGF-I at the molecular and cellular levels by directly transferring the IGF-I gene into neonatal rat brain using virus vectors. Overexpressing IGF-I in vivo would make it more available to the type I IGF receptor residing on all brain cells and limits receptor inhibition by IGF binding proteins and protease degradation. We will verify the transduction of the exogenous IGF-I gene with in situ hybridization and immunocytochemistry. Functionally, the alterations in cellular metabolic levels resulting from IGF-I overexpression will be investigated in the brains of both the normal rat and in rat during and after hypoxia-ischemia-induced injury. Should these studies produce encouraging results, we will have provided strong evidence in establishing IGF-I as one important intervention in hypoxia-ischemia- induced brain damage in neonates.

脑缺氧缺血仍然是严重脑损伤的主要原因 在新生儿中。神经元损伤的分子机制及 后续修复过程并不很好理解， 细胞能量稳态的持续破坏，如 氧化磷酸化、营养吸收和利用的改变。 胰岛素样生长因子I（IGF-I）是一种合成代谢多效性因子 发育中的大脑中的所有细胞类型所需的最佳 增殖、分化和存活。 缺氧缺血后不久 对新生大鼠脑的损伤，IGF-I基因表达降低， 在反应性星形胶质细胞中仅在2-3小时后被激活。 天缺氧后2小时，脑室内输注IGF-I， 缺血性损伤减少了成年大鼠和成年大鼠的神经元损失。 妊娠晚期的胎羊。 这种IGF-I介导的机制 然而，神经保护还不清楚。 我们假设IGF-I 在缺血后早期预防即将发生的神经元损伤， 调节细胞能量代谢。本提案的具体目标 是：1）检查表达和细胞特异性的一个 通过病毒载体递送的外源IGF-I基因; 2）确定 IGF-I对正常大鼠大脑某些方面的调节程度 细胞代谢，如底物摄取、蛋白质合成和 神经元活动;和3）确定是否缺氧-缺血诱导 IGF-I基因表达增强可改善神经元损伤 表情因此，我们将首先研究IGF-I的功能作用， 通过直接将IGF-I基因转移到 新生大鼠脑中的病毒载体。在体内过表达IGF-I 使其更容易被I型IGF受体所利用， 细胞和限制受体抑制IGF结合蛋白和蛋白酶 降解 我们将验证外源IGF-I基因的转导 原位杂交和免疫细胞化学。在功能上， IGF-I导致的细胞代谢水平的改变 将在正常大鼠的脑中研究过表达 在大鼠缺氧缺血性损伤中及损伤后的变化。如果这些 研究产生了令人鼓舞的结果，我们将提供强有力的证据 在建立IGF-I作为一种重要的干预缺氧缺血- 导致新生儿脑损伤。