IMPAIRED SIGNAL TRANSDUCTION BY ALZHEIMERS DISEASE AND GLUCOCORTICOIDS

阿尔茨海默病和糖皮质激素导致的信号传导受损

• 批准号: 6334857
• 负责人: RICHARD S. JOPE
• 金额: $ 19.05万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2002-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6334857
• 关键词: Alzheimer's disease; G protein; acetylcholine; biological signal transduction; cholinergic receptors; enzyme activity; experimental brain lesion; glucocorticoids; hormone regulation /control mechanism; human tissue; hydrolysis; laboratory rat; neurotransmitter metabolism; phosphatidylinositols; phospholipase C; postmortem; protein kinase C; receptor coupling; second messengers; western blottings

Understanding the functional status of signal transduction systems in Alzheimer's disease (AD) and the endogenous regulatory processes for these signal transduction systems is vital for the treatment of this disorder. In AD, cholinergic neurons degenerate but postsynaptic muscarinic receptors remain intact, which led to the therapeutic use of cholinergic agonists, including cholinesterase inhibitors. however, the functional state of the receptors, which are coupled to phosphoinositide (PI) hydrolysis, is unknown. We recently developed a method to measure agonist-induced, GTP- dependent PI hydrolysis in postmortem human brain membranes. Therefore we can now study the functional status of the therapeutically targeted PI- linked receptors in AD and initial studies revealed impaired cholinergic- stimulated PI hydrolysis in AD. Therefore this is the focus of the first specific aim. Understanding how the activity of the PI second messenger system is regulated and is impaired in AD is of critical importance. Neither aging nor lesions cause decreased PI activity, as is seen in AD, but glucocorticoid hormones (e.g., cortisol), which are elevated in AD and which exacerbate age- and toxin-related neurodegeneration, impair the Pi response. Therefore identifying modulatory interactions of glucocorticoid hormones on signal transduction systems associated with PI hydrolysis is the focus of the second specific aim. The first specific aim is to test the hypothesis that agonist-induced PI metabolism can be measured in postmortem human brain, that it is impaired in AD, and that G-protein dysfunction contributes to the impairment. PI hydrolysis will be measured in response to activation of phospholipase C, G-proteins, and several receptor subtypes by agonists in SAD and age- matched control brain regions, using a variety of experimental methods. Western blots will b used to measure protein levels of components of this system, including phospholipase C, G-protein subtypes, and protein kinase C, and G-protein function will be measured. The second specific aim is to test the hypothesis that elevated glucocorticoid hormones impair rat brain signal transduction systems associated with the PI second messenger system, especially when coupled with excitotoxic lesions. Rats will be adrenalectomized, administered glucocorticoids and/or kainate. Cortical and hippocampal IP metabolism, G- protein levels and function, protein kinase C, and gene expression will be measured. The results of this project will greatly increase our knowledge of the function of the PI signal transduction system in AD, will identify specific sites impaired in AD, will identify how glucocorticoids modulate its activity in rat rain, and will identify consequences of glucocorticoid effects at the level of gene expression.

了解信号转导系统的功能状态 阿尔茨海默病 (AD) 及其内源性调节过程 信号转导系统对于治疗这种疾病至关重要。 在 AD 中，胆碱能神经元退化，但突触后毒蕈碱受体 保持完整，这导致了胆碱能激动剂的治疗用途， 包括胆碱酯酶抑制剂。 然而，功能状态 与磷酸肌醇 (PI) 水解偶联的受体是 未知。 我们最近开发了一种方法来测量激动剂诱导的 GTP- 死后人脑膜中依赖的 PI 水解。 因此我们 现在可以研究治疗靶向 PI-的功能状态 AD 中的相关受体和初步研究表明胆碱能受损 刺激 AD 中的 PI 水解。 所以这是第一个重点 具体目标。 了解 PI 第二信使系统的活动情况 AD 中的调节和受损至关重要。 既不老化 病变也不会导致 PI 活性降低，如 AD 中所见，但 糖皮质激素（例如皮质醇）在 AD 和 加剧与年龄和毒素相关的神经变性，损害 Pi 回复。 因此确定糖皮质激素的调节相互作用 与 PI 水解相关的信号转导系统上的激素 第二个具体目标的重点。 第一个具体目标是检验激动剂诱导 PI 的假设 可以在死后的人脑中测量新陈代谢，表明它受到了损害 在 AD 中，G 蛋白功能障碍会导致这种损伤。 PI 将响应磷脂酶 C 的激活来测量水解， G 蛋白以及 SAD 和年龄中激动剂的几种受体亚型 使用各种实验方法匹配控制大脑区域。 蛋白质印迹将用于测量该成分的蛋白质水平 系统，包括磷脂酶 C、G 蛋白亚型和蛋白激酶 将测量 C 和 G 蛋白功能。 第二个具体目标是检验以下假设： 糖皮质激素损害大鼠大脑信号转导系统 与 PI 第二信使系统相关，尤其是耦合时 伴有兴奋性毒性病变。 将对大鼠进行肾上腺切除、给药 糖皮质激素和/或红藻氨酸。 皮质和海马 IP 代谢，G- 蛋白质水平和功能、蛋白激酶 C 和基因表达将 测量。 该项目的成果将极大地增加我们对 PI信号转导系统在AD中的功能，将识别特定的 AD 中受损的部位，将确定糖皮质激素如何调节其 老鼠雨中的活动，并将确定糖皮质激素的后果 基因表达水平的影响。