Nicotinic-Purinergic Modulation of Bladder Contraction

膀胱收缩的烟碱-嘌呤能调节

基本信息

批准号：
7572952
负责人：
GEORGE T SOMOGYI
金额：
$ 28.57万
依托单位：
BAYLOR COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-03-01 至 2011-02-28
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): This proposal is based on the unusual finding in animal models (rat, mouse) that nicotinic receptor agonists significantly enhance the inhibitory action of muscarinic receptor antagonists (atropine, 4-DAMP) on neurally evoked rat bladder contractions, presumably by impairing the non-adrenergic non-cholinergic (NANC component of the contraction. This interaction can be evoked by mixed nicotinic-muscarinic agonists like carbachol, or the cholinergic transmitter acetylcholine, indicating that this finding may have pathophysiological significance, particularly if modulated following bladder injury or insult. For example, the nicotinic-purinergic interaction appears to be constitutively active following spinal cord injury as rat bladders exhibit a higher sensitivity to muscarinic antagonists and, thus, become more 'cholinergic" as compared to normal bladders. In addition, after nicotinic-purinergic interaction the normal rat bladder smooth muscle exhibits much smaller contractions to the purinergic agonist, alpha-beta-methylene ATP suggesting that P2X1 receptor mechanisms may be impacted. We propose to investigate the role of purinergic P2X1 receptors in the nicotinic-purinergic interaction by: 1) utilizing pharmacological methods on the neurally and chemically evoked bladder contractions and 2) measuring changes in intracellular Ca2+ levels by calcium imaging. In addition, we will explore mechanisms underlying changes in nicotinic-purinergic interaction that occur in bladders after spinal cord injury or after bladder outlet obstruction. We hypothesize that the nicotinic binding site is plastic and is already activated in neurogenic bladders, thus explaining why atropine is more effective in inhibiting the neurally evoked contractions. We will utilize RT-PCR and immunohistochemical techniques to identify nicotinic receptor subtypes in normal bladders and to examine whether expression of these specific receptors is altered with SCI or obstruction. Depending on the nicotinic subunits identified with RT-PCR, specific ligands to measure nicotinic receptor binding affinity will be used to more fully characterize the nature of this unusual interaction. Finally, we will utilize readily available nicotinic receptor knockout mice to functionally confirm the modulatory role of specific nicotinic receptors on mouse bladder contractions.

描述（由申请人提供）：该提案是基于动物模型（大鼠，小鼠）中的异常发现，即烟碱受体激动剂显着增强了毒蕈碱受体拮抗剂（阿托品，4-DAMP）对神经诱发的大鼠膀胱收缩的抑制作用，这可能会损害这种非脑蛋白（can）的综合（can cancorment n Interastion（can）。烟碱毒素激动剂（如卡巴醇）或胆碱能发射器乙酰胆碱的混合诱发，表明该发现可能具有病理生理学意义，尤其是在膀胱损伤后调节或侮辱后，烟碱疗法的表现更高。与正常膀胱相比，拮抗剂，因此变得更加“胆碱能”。此外，在烟碱 - 纯素能相互作用之后，正常大鼠膀胱平滑肌表现出对嘌呤能激动剂的收缩较小，呈嘌呤甲基 - 甲基甲基乙烯ATP，表明P2X1受体机制可能会影响P2X1受体机制。我们建议通过以下方式研究嘌呤能P2X1受体在烟碱 - 纯良学相互作用中的作用：1）通过钙成像利用药理学方法对神经和化学诱发的膀胱收缩和化学诱发的膀胱收缩和2）测量细胞内Ca2+水平的变化。此外，我们将探索脊髓损伤或膀胱出口障碍物后膀胱中发生的烟碱 - 纯净相互作用变化的机制。我们假设烟碱结合位点是塑性的，并且已经在神经源性膀胱中被激活，从而解释了为什么阿托品在抑制神经诱发的收缩方面更有效。我们将利用RT-PCR和免疫组织化学技术来鉴定正常膀胱中的烟碱受体亚型，并检查这些特定受体的表达是否随SCI或阻塞而改变。根据用RT-PCR鉴定的烟碱亚基，测量烟碱受体结合亲和力的特定配体将用于更充分地表征这种异常相互作用的性质。最后，我们将利用易于使用的烟碱受体基因敲除小鼠在功能上确认特定烟碱受体在小鼠膀胱收缩上的调节作用。