Studying nicotinic AChRs in histaminergic neurons

研究组胺能神经元中的烟碱 AChR

• 批准号: 7072490
• 负责人: Victor V Uteshev
• 金额: $ 20.11万
• 依托单位: SOUTHERN ILLINOIS UNIVERSITY CARBONDALE
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-30 至 2008-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7072490
• 关键词: attention; brain; choline; histamine; homeostasis; neurons; nicotine

DESCRIPTION (provided by applicant): Neurons of the tuberomammillary (TM) hypothalamic nucleus represent the major source of histamine in the brain and project their axons to most brain regions to control attention and arousal, as evidenced by the sedation caused by anti-histamines. Alpha-bungarotoxin-sensitive nicotinic acetylcholine receptors (nAChRs), whose kinetics and pharmacology are similar to those of highly Ca2+-permeable homomeric a7 nAChRs, are the only nAChRs expressed in TM neurons in high densities. Our experiments have shown that activation of TM nAChRs does not elevate cytosolic Ca2+ concentrations ([Ca2+]i) in TM somata in the absence of voltage-gated Ca2+ channels (VGCCs). Therefore, the kinetics of a7-like nAChRs and functional links among a7-like nAChRs and other TM Ca2+ sources become the key factors determining the impact of a7-like nAChR activation on [Ca2+]i. This implication is important because the physiological role of a7 nAChRs remains unknown, and may involve cytoprotection and regulation of TM histaminergic function by endogenous and therapeutic nicotinic agents, such as choline and nicotine. Aim 1 will test the hypothesis that TM a7-like nAChRs are heteromeric (involve non-a7 subunits), whose permeability to Ca2+ ions is lower than that of homomeric a7 nAChRs. Accordingly, Aim 2 will test the hypothesis that a7-like nAChRs regulate TM [Ca2+]i indirectly, via functional links to key Ca2+ sources: VGCCs; Ca2+ stores; and Na+-Ca2+ exchangers. We will use Ca2+ imaging and patch-clamp; reverse transcription polymerase chain reaction; Western blot and immunohistochemistry to determine the nature of a7-like nAChRs; mechanisms of [Ca2+]i regulation, and links among a7-like nAChRs and other key Ca2+ sources in TM neurons. The proposed study will provide important information regarding the nature of a7-like nAChRs in histaminergic TM neurons; and a7-like nAChR-driven mechanisms of regulation of Ca2+ homeostasis implicated in cytoprotection and regulation of histaminergic function, linking cholinergic and histaminergic brain systems. Intriguingly, the behavioral and cognitive effects of nicotine and histamine are similar: both agents are anti-nociceptive; improve attention; promote alertness and arousal; and inhibit food intake. Some of these effects of nicotine and therapeutic nicotinic agents may arise from their ability to modulate histaminergic function.

描述（由申请人提供）：结核氨基（TM）下丘脑核的神经元代表了大脑中组胺的主要组胺来源，并将其轴突投射到大多数大脑区域以控制注意力和唤醒，这是由抗赫斯塔明引起的镇静作用的。 α-甲状腺毒素敏感的烟碱乙酰胆碱受体（NACHRS），其动力学和药理学与高度高密度的TM神经元中唯一表达的NACHR相似。我们的实验表明，在没有电压门控的Ca2+通道（VGCC）的情况下，TM NACHR的激活不会升高TM Somata中的胞质Ca2+浓度（[Ca2+] I）。因此，A7样NACHR和其他TM Ca2+源之间的A7样NACHR和功能联系的动力学成为决定A7样NACHR激活[Ca2+] i的影响的关键因素。这一含义很重要，因为A7 NACHR的生理作用仍然未知，并且可能涉及内源性和治疗性烟碱剂（例如胆碱和尼古丁）对TM组蛋白功能功能的细胞保护和调节。 AIM 1将检验以下假设：TM A7样nACHR是异类（涉及非A7亚基），其对Ca2+离子的渗透性低于同源A7 NACHR的渗透性。因此，AIM 2将通过与关键Ca2+源的功能链接：VGCCS的功能链接来测试A7样NACHR [Ca2+] I间接调节TM [Ca2+] i的假设； Ca2+商店；和Na+ -ca2+交换器。我们将使用Ca2+成像和贴片钳；逆转录聚合酶链反应；蛋白质印迹和免疫组织化学，以确定a7样nACHR的性质； [Ca2+] I调控的机制，以及TM神经元中A7样NACHR和其他关键Ca2+源之间的联系。拟议的研究将提供有关组胺能TM神经元中A7样NACHR的性质的重要信息；以及与胆碱能和组胺能脑系统相关的Ca2+稳态调节的A7样NACHR驱动的机制。有趣的是，尼古丁和组胺的行为和认知作用相似：两种药物都是抗伤害感受的。提高注意力；促进警觉和唤醒；并抑制食物摄入量。尼古丁和治疗性烟碱剂的某些作用可能是由于调节组蛋白能功能的能力而产生的。