NICOTINE MEDIATED SODIUM FLUX IN PRIMARY CULTURES

原代培养物中尼古丁介导的钠通量

基本信息

批准号：
3424098
负责人：
Barbara J Morley
金额：
$ 7.16万
依托单位：
FATHER FLANAGAN'S BOYS' HOME
依托单位国家：
美国
项目类别：
财政年份：
1991
资助国家：
美国
起止时间：
1991-03-01 至 1993-10-31
项目状态：
已结题

项目摘要

Eighty percent of smokers who quit relapse within a year. Although there are many reasons for relapse, the active ingredient in cigarettes, nicotine, has properties of an addictive substance. All of the actions of nicotine are not known, but nicotine is known to act as receptor sites in nervous tissues. Its action at acetylcholine receptor sites may be related to its addictive properties. The nicotinic acetylcholine receptors in mammalian brain have not been well-characterized. Nicotine binds with high affinity (Kd 1-10 nM) to at least one population of brain nicotinic receptors. The high-affinity binding to brain tissue is a paradox. Electrophysiological studies suggest that micromolar concentrations of nicotine are necessary for receptor activation. It has been suggested that the brain receptors are desensitized during the assay procedure (in which 10-20 nM concentrations of nicotine are used), indicating a 1000-fold difference between the K-activation (K- act) and K-desensitization (K-des) of nicotinic receptors in mammalian brain. Previous work in our laboratory indicates that the K-act and K-des of PC12 cells, which possess a well-characterized neuronal receptor, are 7.7 X 10(5) M and 8.2 X 10(5) M, respectively. On the basis of these data, we question whether the K-des and K-act in brain tissue would differ by 3 orders of magnitude. This question cannot be resolved using brain tissue in vivo. We therefore propose to study this question in primary neuronal brain cultures using 22Na+ influx. 22Na+ influx has not previously been demonstrated in primary neuronal cultures derived from mammalian brain. Therefore, the goal of this research is to demonstrate nicotinic receptor mediated 22Na" influx in mammalian brain culture. Experiments using 22Na+ influx and nicotine and cytisine as agonists will be performed to determine the K-act and K-des of the receptors. Influx will be also carried out in the presence of nicotinic antagonists. These experiments will serve as the basis for future inves- tigations of the physiological properties of brain nicotinic receptors.

百分之八十的戒烟者在一年内复吸。虽然有复吸的原因有很多，香烟中的活性成分，尼古丁具有成瘾物质的特性。的所有行动尼古丁尚不清楚，但已知尼古丁可作为受体位点神经组织。它在乙酰胆碱受体位点的作用可能与其令人上瘾的特性。哺乳动物大脑中的烟碱乙酰胆碱受体尚未被研究特点鲜明。尼古丁以高亲和力 (Kd 1-10 nM) 结合至至少一组大脑烟碱受体。高亲和力与脑组织的结合是一个悖论。电生理学研究表明微摩尔浓度的尼古丁对于受体来说是必需的激活。有人认为大脑受体已脱敏在检测过程中（其中 10-20 nM 浓度的尼古丁使用），表明 K-激活（K- act）和哺乳动物烟碱受体的K-脱敏（K-des）脑。我们实验室之前的工作表明PC12的K-act和K-des 具有特征明确的神经元受体的细胞是 7.7 X 分别为 10(5) M 和 8.2 X 10(5) M。根据这些数据，我们质疑脑组织中的 K-des 和 K-act 是否会相差 3 数量级。这个问题不能用脑组织来解决体内。因此，我们建议在初级神经元中研究这个问题使用 22Na+ 流入进行脑培养。 22Na+ 流入先前尚未在原代神经元中得到证实源自哺乳动物大脑的培养物。因此，本研究的目标是为了证明哺乳动物中烟碱受体介导的 22Na" 流入大脑文化。使用 22Na+ 流入以及尼古丁和金雀花碱作为实验将进行激动剂以确定 K-act 和 K-des 受体。 Influx 也将在烟碱存在的情况下进行对手。这些实验将作为未来研究的基础大脑烟碱受体的生理特性的作用。