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 阿尔茨海默氏病（AD）和内源性调节过程 信号转导系统对于治疗该疾病至关重要。 在AD中，胆碱能神经元退化但突触后毒蕈碱受体 保持完好无损，导致胆碱能激动剂的治疗使用， 包括胆碱酯酶抑制剂。 但是， 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测量激动剂诱导的GTP-的方法 死后人脑膜中的依赖性PI水解。 因此我们 现在可以研究治疗靶向的PI的功能状态 AD和初步研究中的关联受体揭示了胆碱能的受损 AD中刺激的PI水解。 因此，这是第一个的重点 具体目标。 了解PI第二信使系统的活动是如何的 受监管和受损的AD至关重要。 都不衰老 如AD中所见，病变不会导致PI活性降低，但是 糖皮质激素激素（例如皮质醇），在AD中升高，并且 加剧了年龄和毒素相关的神经变性，损害了PI 回复。 因此鉴定糖皮质激素的调节性相互作用 与PI水解相关的信号转导系统上的激素是 第二个特定目标的重点。 第一个具体目的是检验激动剂诱导的PI的假设 代谢可以在死后人脑中测量，以使其受损 在AD中，G蛋白功能障碍有助于损害。 pi 水解将根据磷脂酶C的激活来测量 g蛋白和激动剂的几种受体亚型 使用多种实验方法匹配的对照脑区域。 Western印迹将B用于测量其成分的蛋白质水平 系统，包括磷脂酶C，G蛋白亚型和蛋白激酶 C将测量C和G蛋白功能。 第二个具体目的是检验升高的假设 糖皮质激素损害大鼠脑信号转导系统 与PI第二信使系统相关联，尤其是当耦合时 兴奋性病变。 大鼠将进行肾上腺切除术，给药 糖皮质激素和/或海藻酸盐。 皮质和海马IP代谢，G- 蛋白质水平和功能，蛋白激酶C和基因表达将是 测量。 该项目的结果将大大增加我们对 AD中PI信号转导系统的功能，将确定特定 AD中受损的站点将确定糖皮质激素如何调节其 大鼠雨的活性，并将确定糖皮质激素的后果 基因表达水平的影响。