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: 2891995
• 负责人: Wei-Hua Lee
• 金额: $ 11.02万
• 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 2001-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2891995
• 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 随后的修复过程尚不清楚，但可能涉及 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因子 发育中的大脑中所有细胞类型都需要最佳的 增殖、分化和存活。 缺氧缺血后不久 损伤新生大鼠大脑，IGF-I 基因表达降低 脆弱的神经元仅在 2-3 年后在反应性星形胶质细胞中被激活 天。缺氧后两小时脑室内输注 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 妊娠晚期的胎羔。 IGF-I介导的机制 然而，神经保护作用尚不清楚。 我们假设 IGF-I 通过以下方式预防缺血后早期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 由病毒载体递送的外源IGF-I基因； 2）确定 IGF-I 调节正常大鼠大脑某些方面的程度 细胞代谢，例如底物摄取、蛋白质合成和 神经元活动； 3）确定是否缺氧缺血引起 IGF-I 基因增强可改善神经元损伤 表达。因此，我们首先研究 IGF-I 在 通过将 IGF-I 基因直接转移到分子和细胞水平 使用病毒载体的新生大鼠大脑。体内过度表达 IGF-I 会 使其更容易被全脑的 I 型 IGF 受体利用 细胞并限制 IGF 结合蛋白和蛋白酶对受体的抑制 降解。 我们将验证外源IGF-I基因的转导 与原位杂交和免疫细胞化学。从功能上来说， IGF-I 引起的细胞代谢水平的改变 将在正常大鼠的大脑中研究过度表达 以及在缺氧缺血引起的损伤期间和之后的大鼠中。应该这些 研究产生令人鼓舞的结果，我们将提供强有力的证据 建立 IGF-I 作为缺氧缺血的重要干预措施 诱发新生儿脑损伤。