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.

在持续项目期间的研究将主要基于一个关键的发现，在过去的一年里，从自发性高血压大鼠（SHR）和布朗挪威血统的同源品系的大鼠。该菌株在8号染色体中含有一个31 cM的替换到SHR背景中，并且非常偶然的是，该区域含有一簇烟碱乙酰胆碱受体基因，其编码在CNS中表达的受体亚基（α 3、β 4和α 7）。这些动物显示相对于它们的SHR对应物降低的血压（收缩压和舒张压）。更重要的是，鞘内给药烟碱受体激动剂显示明显减少的升压和伤害性反应。有时我们认为SHR的特征是兴奋性增强的特征之一，随着动物年龄的增长，血压成为这一点的表现之一。如果我们考虑更广泛的兴奋性反应，在突触前控制神经递质释放的明显放大位点将是一个合乎逻辑的起点。最近的工作也证明，大多数烟碱受体似乎位于突触前脊髓和脊髓上区域。我们选择研究脊髓系统，并不是因为我们相信它是一个全面控制高血压的区域，而是因为在清醒的动物中，可以监测到注射到节段性脊髓区域的烟碱激动剂的升压反应。反过来，已经并将测量靶受体数量、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，我们建议更全面地描述清醒SHR和SHR-Lx大鼠的升压反应，然后开始通过划定烟碱受体基因簇周围的区域来定位负责不同升压反应的基因。如果反应仍然与AChR基因取代，我们将试图确定这三个基因参与，通过编码和关键非编码区的表征。其他显示数量性状基因座的区域也将被调查。由于脊髓烟碱受体激动剂的反应窗口增强，我们将通过使用免疫细胞化学和共聚焦显微镜的特点，在这一地区的受体和递质的本地化。此外，通过使用辣椒素和物质P-皂草素缀合物，相对特异性的细胞消融在脊髓中是可能的，并且通过比较治疗和未治疗的动物的改变的升压反应，我们应该能够映射参与改变的反应的脊髓通路和受体亚型。