Calcium Signaling by Hippocampal Nicotinic Receptors

描述(申请人提供)：尼古丁是一种形成习惯的药物， 在我们的社会中被广泛使用。烟碱的广泛分布 大脑中的乙酰胆碱受体(NAChRs)表明， 尼古丁在人类中的使用很可能是复杂的。了解机制 尼古丁在中枢神经系统中的作用必须从阐明 不同脑区nAChR亚型的功能。我们的发现是，海马体 星形胶质细胞表达功能性nAChRs提示这些受体可能在 尼古丁在星形细胞信号中的作用以及尼古丁的一些作用可能是 由星形胶质细胞调节。 我们建议研究nAChR激活的钙信号在星状体内的传播 海马区星形胶质细胞培养，应用荧光成像技术。这个 NAChRs导致谷氨酸释放与囊泡一致的能力 胞吐作用将在转染NMDA的HEK 293细胞上进行检测 受体，结合全细胞电压钳测量。.的存在 全细胞电压钳原位检测星形胶质细胞上的nAChRs GFAP/GFP转基因海马片星形胶质细胞的测量 老鼠。NAChR介导的钙信号将使用Fura 2 AM负载进行检测 GFAP/GFP小鼠海马片星形胶质细胞。有没有可能 尼古丁对谷氨酸能微小兴奋电流的调制作用 (Mepscs)是由于信号放大，从储存的钙释放出来的 用电生理技术在海马片上进行检查。一个 星形胶质细胞nAChRs在突触活动调节中的潜在作用 将用培养的海马神经元在有无的情况下进行检查 星形胶质细胞。 该项目的结果将展示nAChRs在 星形胶质细胞可以特异性地改变海马区功能和神经元信号 总体来说，也提示星形细胞nAChRs在调节 尼古丁的影响。

DESCRIPTION (provided by applicant): Nicotine is a habit-forming drug that is widely used in our society. The widespread distribution of nicotinic acetylcholine receptors (nAChRs) in the brain suggests that the dynamics of nicotine use in humans is likely to be complex. Understanding mechanisms underlying the action of nicotine in the CNS must begin with the elucidation of the function of various brain nAChR subtypes. Our findings that hippocampal astrocytes express functional nAChRs suggest that these receptors might play a role in astrocytic signaling and that some of the actions of nicotine might be mediated by astrocytes. We propose to examine the spread of nAChR-activated calcium signals in stellate hippocampal astrocytes in culture, using fluorescence imaging techniques. The ability of nAChRs to cause release of glutamate consistent with vesicular exocytosis will be examined using HEK 293 cells transfected with NMDA receptors, combined with whole cell voltage-clamp measurements. The presence of nAChRs on astrocytes in situ will be determined by whole cell voltage-clamp measurements from astrocytes in hippocampal slices from GFAP/GFP transgenic mice. nAChR-mediated calcium signaling will be examined using fura 2 AM loaded astrocytes in hippocampal slices from the GFAP/GFP mice. The possibility that nicotine-induced modulation of glutamatergic miniature excitatory currents (mepscs) is due to amplification of signals from store calcium release will be examined using electrophysiological techniques in hippocampal slices. A potential role for astrocytic nAChRs in the regulation of synaptic activity will be examined using hippocampal neurons cultured in the presence and absence of astrocytes. Results from this project will demonstrate mechanisms by which nAChRs on astrocytes could alter hippocampal function specifically and neuronal signaling in general and also suggest a role for astrocytic nAChRs in mediating the effects of nicotine.