CENTRAL NICOTINIC RECEPTORS IN HYPERTENSION

高血压中枢烟碱受体

基本信息

批准号：
6109787
负责人：
PALMER William TAYLOR
金额：
$ 25.51万
依托单位：
UNIVERSITY OF CALIFORNIA, SAN DIEGO
依托单位国家：
美国
项目类别：
财政年份：
1999
资助国家：
美国
起止时间：
1999-07-01 至 2000-06-30
项目状态：
已结题

项目摘要

The propose research in project 5 is based on two working hypotheses: (a) spinal nicotinic cholinergic neurotransmission is a critical pathway in the maintenance of blood pressure and in mediating pressor responses elicited by external stimulae; (b) certain hypertensive phenotypes with a genetic basis result from hyper-excitability of the nicotinic system which amplifies responses to central stimulation through control by presynaptic receptors. Thus, hypertension and enhanced startle responses may be critical manifestations of hyper-excitability spinal nicotinic receptor regulated pathways. In the past award period we have mapped some of the critical pathways involved in the spinal pressor response, described differential responses to nicotinic agonists and examined amino acid release and nicotinic receptor densities in spontaneously hypertensive rat (SHR) and control (WKY) rats. We plan to extend these studies to recombinant inbred strains and to hypertension models that do not have a primary, central neurogenic component in order to determine whether nicotinic hyperexcitability cosegregates with hypertension and whether it is confined to neurogenic hypertension with a genetic origin. Recently, we developed an intrathecal microdialysis system that enables injection of nicotinic agonists and measurement of released neurotransmitters into the intrathecal space in apposition to the injection site. This cellular endpoint of neurotransmitter release will be correlated with radioligand detection of receptors by autoradiography in spinal sections and with the pharmacologic endpoints. These techniques will enable us to extend our analysis to the cellular and molecular levels. These studies will initially be directed to completing our analysis of nicotinic agonist mediated release of excitatory amino acids and then extending the studies to release of acetylcholine, substance P and catecholamines. We propose to identify cellular mediators such as intracellular Ca2+ and regulators of gene expression that may be responsible for the enhanced excitability of the spinal responses. These studies will interface with Projects 1 and 2. Specific procedures for ablation of primary afferents, ascending and descending pathways and interneurons have been developed and the influence of these interventions will be examined on the responses in the intact animal, the cellular response of transmitter release and the loss of nicotinic receptor subtypes and their localization. Second, we will examine the specificity and subtypes of nicotinic receptors involved through the use of receptor selective ligands, immunoprecipitation, and autoradiography and plan to correlate this information with the loci of genes affecting hypertension. Third, receptor subtype expression in the spinal cord will be correlated with the mRNA species through message protection and in situ hybridization.

项目5中的建议研究基于两个工作假设：（a）脊柱烟碱胆碱能神经传递是关键的途径维持血压和介导的压力反应由外部刺激引起；（b）某些具有A的高血压表型烟碱系统的过度兴奋性产生的遗传基础通过突触前控制对中央刺激的反应放大受体。因此，高血压和增强的惊吓反应可能是脊柱烟碱受体的临界表现规范的途径。在过去的奖项期间，我们绘制了一些描述的脊柱压力反应中涉及的临界途径对烟碱激动剂的差异反应并检查了氨基酸自发性高血压大鼠的释放和烟碱受体密度（SHR）和对照（WKY）大鼠。我们计划将这些研究扩展到重组近交菌株和没有没有一个的高血压模型主要的中央神经源成分，以确定是否烟碱过度兴奋性高血压，以及它是否是否仅限于具有遗传来源的神经源性高血压。最近，我们开发了一种鞘内微透析系统，该系统可以注射烟碱激动剂和释放神经递质的测量注射部位的鞘内空间。这个细胞神经递质释放的终点将与放射性物体相关通过脊柱切片和随之而来的自显影检测受体药理学终点。这些技术将使我们能够扩展我们的分析细胞和分子水平。这些研究会最初可以完成我们对烟碱激动剂的分析介导的兴奋性氨基酸的释放，然后扩展研究释放乙酰胆碱，物质P和儿茶酚胺。我们建议鉴定细胞介质，例如细胞内Ca2+和调节剂可能导致增强兴奋性的基因表达脊柱反应。这些研究将与项目1和2进行接口。消融主要传入，上升和已经开发了下降的途径和中间神经元和影响这些干预措施将在完整的响应中进行检查动物，发射器释放的细胞反应和丢失烟碱受体亚型及其本地化。第二，我们会的检查涉及烟碱受体的特异性和亚型通过使用受体选择性配体，免疫沉淀和放射自显影并计划将这些信息与影响高血压的基因。第三，受体亚型表达脊髓将通过消息与mRNA物种相关保护和原位杂交。