CHRONIC MORPHINE--REGULATION OF ION CONDUCTANCES

慢性吗啡——离子电导的调节

• 批准号: 2120636
• 负责人: JOHN T WILLIAMS
• 金额: $ 14.69万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-04-01 至 1997-03-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2120636
• 关键词: G protein; adenylate cyclase; cyclic AMP; drug interactions; drug tolerance; electrical conductance; electrical potential; electrophysiology; enzyme activity; forskolin; glutamate receptor; glutamates; guinea pigs; laboratory rat; locus coeruleus; microelectrodes; morphine; neurons; neurotransmitter transport; norepinephrine; opioid receptor; phosphatase inhibitor; potassium; potassium channel; receptor coupling; receptor expression; second messengers; spinal trigeminal nucleus; stimulant /agonist; voltage gated channel

The experiments in this proposal are aimed at uncovering adaptive changes in neuronal activity that result from chronic opioid treatment. Behaviorally it can be observed that a high degree of tolerance to and dependence on morphine develops with chronic use. It is curious that, at the cellular and biochemical level, the degree of tolerance and dependence is orders of magnitude smaller. The disparity in the observations may suggest that there are multiple mechanisms arranged in series that could account for the high level of behavioral tolerance. Another possibility is that regulation of ion conductances other than those directly affected by opioids are altered with chronic treatment and they may account for the increased level of tolerance and dependence. Opioids activate potassium channels and/or the inactive calcium channels to perturb cell excitability and function. In the continued presence of opioids, tolerance develops to these direct actions of opioids. There are, in addition, other adaptive changes in cell function and excitability not directly related to the specific ion channels gated by opioids. The regulation of those channels 'indirectly' gated by opioids is the subject of this proposal. Intracellular and whole cell recordings from neurons in the locus coeruleus and substantia gelatinosa of the spinal trigeminal nucleus will be made in brain slice preparations. With these two preparations, two opioid mediated responses will be investigated, the increase in potassium conductance and the presynaptic inhibition of glutamate release. One consistent observation made with chronic opioid treatment is an increase in the basal and stimulated level of cAMP. In this proposal, the effects of cAMP-dependent processes on transmitter release and ion conductances gated by voltage, transmitters and G- proteins will be identified and characterized. These cAMP-dependent processes will be studied after acute application (min or hours) of opioid agonists and in animals treated chronically (days) with morphine. By investigating the alteration in the regulation of ion conductances not directly affected by opioids, it may be possible to clarify the mechanisms by which the high levels of tolerance found at the behavioral level are generated.

本提案中的实验旨在揭示适应性 长期阿片类药物治疗导致的神经元活动变化。 从行为上可以看出，对和 长期使用吗啡会产生依赖性。 令人好奇的是， 在细胞和生化水平上，耐受程度和 依赖性要小几个数量级。 的差距 观察结果可能表明存在多种机制 系列可以解释高水平的行为 宽容。 另一种可能性是离子电导的调节 除了直接受阿片类药物影响的因素外，其他因素也会随着慢性药物的改变而改变 治疗，它们可能是耐受性水平增加的原因 依赖性。 阿片类药物激活钾通道和/或非活性钙 干扰细胞兴奋性和功能的通道。 在持续的 阿片类药物的存在，会对这些直接作用产生耐受性 阿片类药物。 此外，细胞还存在其他适应性变化 功能和兴奋性与特定离子没有直接关系 由阿片类药物控制的通道。 对这些渠道的监管 由阿片类药物“间接”控制是该提案的主题。 来自该位点神经元的细胞内和全细胞记录 三叉神经脊核的蓝核和胶质 将在脑切片中制备。 有了这两个准备， 将研究两种阿片类药物介导的反应， 钾电导和谷氨酸的突触前抑制 发布。 对长期阿片类药物治疗进行的一项一致观察 是 cAMP 基础水平和刺激水平的增加。 在这个 提议，cAMP依赖性过程对发射机的影响 由电压、发射器和 G- 控制的释放和离子电导 蛋白质将被鉴定和表征。 这些 cAMP 依赖性 急性应用（分钟或小时）后将研究过程 阿片类激动剂和长期（数天）接受阿片类激动剂治疗的动物 吗啡。 通过研究离子调节的变化 电导不直接受阿片类药物影响，因此可能 阐明高水平耐受性的机制 行为水平被生成。