MECHANISMS OF SIGNAL TRANSDUCTION OF CARDIAC OPIOID RECEPTOR STIMULATION

心脏阿片受体刺激的信号传导机制

• 批准号: 2565764
• 负责人: S PEPE
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/2565764
• 关键词: aging; beta adrenergic receptor; biological signal transduction; cyclic AMP; endogenous opioid; enkephalins; enzyme activity; heart cell; heart pharmacology; inositol phosphates; laboratory rat; leucine; opioid receptor; pertussis toxin; protein kinase C; receptor coupling

Although opioid peptides (OP) are: coreleased with catecholamines from neuronal endings in the heart; are produced and secreted by cardiac myocytes; capable of activating OP receptors (OPR) which reside on cardiac cell membranes; the physiological role of OP's in cardiac function and pathophysiology,including the mechanism of signal transduction,has received meager investigation. Thus we have recently shown that OP's have a postsynaptic cardiac intracellular signalling role which involves a potent "cross-talk" with the beta1-adrenergic receptor (beta1-AR) stimulation pathway. This work identified that the cross-talk between delta-OPR and beta1-AR occurs via a pertussis toxin sensitive (PTX) Gi-protein involved with adenylyl cyclase inhibition in intact isolated heart preparations and isolated cardiac myocytes. In non-cardiac cells, although delta-OPR exert direct effects which involve the activation of phospholipase C for phosphoinositide metabolism and IP3 formation, direct evidence that demonstrates delta-OPR coupling to either pertussis toxin-insensitive Gq-protein or PTX-sensitive Gi-protein is unavailable to date. This lab has previously shown that a dose-dependant negative inotropic effect, including inhibition of intracellular [Ca2+]and whole cell voltage, occurs in cardiac myocytes. We have also previously shown that OP's and their preproenkephalin mRNA are significantly increased with age. In light of these findings, a study of the direct effects of -OPR stimulation by leucine-enkephalin (LE) in 6-hydroxydopamine pretreated isolated hearts from young adult (6mo)and old rats (24mo)is in progress. LE reduced peak systolic pressure in a dose dependent manner in 6 and 24mo rats but to a greater extent in 24mo rats. The EC50 was approximately 10-8 M LE in 6 mo but 10-9M LE in 24mo hearts (p less than 0.05,n=4). A preliminary assessment of the role of PTX-sensitive Gi-protein in the direct effects of LE indicated that PTX pretreatment did not inhibit the LE-induced negative inotropy in either age group, as is LE's interactive effect with the beta1-AR signalling transduction pathway. Assays for the measurement of cAMP, IP3 and PKC in isolated hearts from all groups are in progress. The cross-talk between -OPR and beta1-AR signal transduction pathways is an important mechanism in the regulation of cardiac excitation-contraction coupling. Presently, our data indicates that two types of G-protein are coupled to the delta-OPR that are involved with the interactive and direct effects of opioid peptides. Complete elucidation of these intracellular signal transduction pathways and their mechanism of action, particularly during the process of aging or disease remains the focus of this project.

虽然阿片肽（OP）是：与儿茶酚胺共同释放， 心脏中的神经末梢;由心脏产生和分泌 肌细胞;能够激活OP受体（OPR）， 心脏细胞膜; OP在心脏功能中的生理作用 病理生理学，包括信号转导机制， 接受了不充分的调查。因此，我们最近表明，OP的 具有突触后心脏细胞内信号传导作用， 与β 1-肾上腺素能受体（β 1-AR）的有效“串扰” 刺激途径这项工作确定， δ-OPR和β 1-AR通过百日咳毒素敏感（PTX） 在完整的分离细胞中参与腺苷酸环化酶抑制的Gi蛋白 心脏制备物和分离的心肌细胞。在非心肌细胞中， 虽然 δ-OPR发挥直接作用，涉及激活 磷脂酶C，用于磷酸肌醇代谢和IP 3形成，直接 证据表明 与百日咳毒素不敏感的Gq蛋白或 迄今为止，PTX敏感的Gi蛋白不可用。该实验室此前 显示剂量依赖性负性肌力作用，包括 细胞内[Ca 2 +]和全细胞电压的抑制，发生在心脏 肌细胞我们以前也表明，OP及其 前脑啡肽原mRNA随年龄增长而显著增加。鉴于 这些发现，一项研究的直接影响 6-羟基多巴胺中亮氨酸-脑啡肽（LE）的-OPR刺激 用预处理的青年（6月龄）和老年（24月龄）大鼠离体心脏， 中求进工作总LE以剂量依赖性方式降低峰值收缩压 在6和24月龄大鼠中，但在24月龄大鼠中更大程度上。EC 50为 6个月时约为10-8 M LE，24个月时约为10- 9 M LE（P <0.05）。 0.05，n =4）。对PTX敏感的作用的初步评估 在LE的直接作用中，Gi蛋白的表达表明PTX预处理 在任一年龄组中均不抑制LE诱导的负性肌力， LE与β 1-AR信号转导通路的相互作用。 测定离体心脏中cAMP、IP 3和PKC的测定 所有小组都在进行中。之间的串扰 -OPR和β 1-AR信号转导通路是一个重要的 心脏兴奋-收缩偶联的调节机制。 目前，我们的数据表明，两种类型的G蛋白偶联到 的 delta-OPR涉及的交互和直接影响， 阿片肽完整阐明这些细胞内信号 转导途径及其作用机制，特别是在 衰老或疾病的过程仍然是这个项目的重点。