Central nicotinic receptors in hypertension

高血压中枢烟碱受体

• 批准号: 7393843
• 负责人: PALMER William TAYLOR
• 金额: $ 45.83万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7393843
• 关键词: Ablation; Age; Animals; Area; Autoradiography; Behavioral; Biological Assay; Blood Pressure; Brain; C Fiber; California; Candidate Disease Gene; Capsaicin; Cardiovascular system; Cells; Chromosomes, Human, Pair 8; Code; Complement; Confocal Microscopy; Congenic Strain; Conscious; DNA Resequencing; Disease; Dopamine; Event; Gene Cluster; Gene Transfer; Genes; Genetic Models; Genetic Polymorphism; Human; Hypertension; Immunohistochemistry; Immunoprecipitation; Inbred SHR Rats; Laboratories; Ligand Binding; Link; Localized; Maps; Measurement; Measures; Mediating; Mediator of activation protein; Microdialysis; Molecular; Monitor; Neurons; Neurotransmitter Receptor; Nicotine; Nicotinic Agonists; Nicotinic Receptors; Norway; Numbers; Pathway interactions; Phenotype; Population; Potassium Channel; Quantitative Trait Loci; Rat Strains; Rattus; Receptor Gene; Reflex action; Relative (related person); Spinal; Spinal Cord; Substance P Receptor; System; Techniques; Tobacco; Work; base; blood pressure regulation; cell type; congenic; familial hypertension; immunocytochemistry; neurotransmitter release; nociceptive response; presynaptic; progenitor; programs; receptor; response; somatosensory; spinal pathway; substance P-saporin; trait

Studies in the continuing project period will be based primarily on a critical finding, made over the last year with a congenic strain of rats derived from the Spontaneously Hypertensive Rat (SHR) and Brown Norway parentage. This strain contains a 3 lcM replacement in chromosome 8 into the SHR background, and quite fortuitously this region contains a cluster of nicotinic acetylcholine receptor genes that encode receptor subunits expressed in the CNS (alpha3, beta4 and alpha7). These animals show diminished blood pressure (systolic and diastolic) relative to their SHR counterparts. More importantly, intrathecal administration of nicotinic agonists shows markedly diminished pressor and nociceptive responses. For sometime we have felt that the SHR trait was one of enhanced excitability, and as the animal ages, blood pressure becomes one manifestation of this. If we consider more widespread excitability responses, loci of amplification evident in the presynaptic control of neurotransmitter release would be a logical starting point. Recent work has also documented that most nicotinic receptors appear to lie presynaptically in spinal and supraspinal regions. We have chosen to study the spinal system, not because we believe it to be an area that globally controls hypertension, but rather pressor responses to nicotinic agonists injected into segmental cord areas can be monitored in the conscious animal. In turn, measurements of target receptor number, their subtypes, cellular responses (ie: release of neurotransmitters detected in microdialysates), and the cellular localization of neurotransmitter and receptor subtype in various lamina and cell types in the cord have been and will be measured. Accordingly, we propose to more fully characterize the pressor response in conscious SHR and SHR-Lx rats, and then begin to localize the gene(s) responsible for the different pressor response by delimiting the region around the nicotinic receptor gene cluster. If the response remains associated with the AChR gene substitution, we then will attempt to identify which of the three genes are involved, through a characterization of the coding and critical noncoding regions. Other regions showing quantitative trait loci will also be investigated. Since the window of the response to spinal nicotinic agonists is augmented, we will characterize the localization of receptors and transmitters in this region through the use of immunocytochemistry and confocal microscopy. In addition, relatively specific cell ablation is possible in the spinal cord through the use of capsaicin and a Substance P-saporin conjuate, and by comparing altered pressor responses of treated and untreated animals, we should be able to map spinal pathways and receptor subtypes involved in the altered responses.

持续项目期间的研究将主要基于去年对源自自发性高血压大鼠（SHR）和棕色挪威血统的同源大鼠品系的一项关键发现。该菌株在 SHR 背景中的 8 号染色体上包含 3 lcM 的替换，并且非常偶然的是，该区域包含一组烟碱乙酰胆碱受体基因，这些基因编码在 CNS 中表达的受体亚基（α3、β4 和 α7）。与 SHR 动物相比，这些动物的血压（收缩压和舒张压）较低。更重要的是，烟碱激动剂的鞘内给药显示升压和伤害性反应显着减弱。一段时间以来，我们认为 SHR 特征是兴奋性增强的一种特征，随着动物年龄的增长，血压成为这种特征的一种表现。如果我们考虑更广泛的兴奋性反应，神经递质释放的突触前控制中明显的放大位点将是一个逻辑起点。最近的研究还证明，大多数烟碱受体似乎位于脊髓和脊髓上区域的突触前。我们选择研究脊柱系统，并不是因为我们相信它是一个全局控制高血压的区域，而是因为可以在有意识的动物中监测注射到节段性脊髓区域的烟碱激动剂的升压反应。反过来，已经并将测量目标受体数量、其亚型、细胞反应（即：在微透析液中检测到的神经递质的释放）以及神经递质和受体亚型在脊髓中各种层和细胞类型中的细胞定位。因此，我们建议更全面地表征有意识的 SHR 和 SHR-Lx 大鼠的升压反应，然后通过界定烟碱受体基因簇周围的区域来开始定位负责不同升压反应的基因。如果反应仍然与 AChR 基因替换相关，那么我们将尝试通过编码区和关键非编码区的表征来确定涉及三个基因中的哪一个。还将研究显示数量性状基因座的其他区域。由于对脊髓烟碱激动剂的反应窗口扩大，我们将通过使用免疫细胞化学和共聚焦显微镜来表征该区域中受体和递质的定位。此外，通过使用辣椒素和 P-皂草素结合物，可以在脊髓中进行相对特异性的细胞消融，并且通过比较治疗和未治疗动物的升压反应改变，我们应该能够绘制出脊髓通路和参与改变反应的受体亚型。