MOLECULAR APPROACHES TO DRUGS OF ABUSE AND AROUSAL STATE

该提案主要集中在尼古丁对人体的影响上。 视交叉上核（SCN），哺乳动物生物钟的所在地， 对唤醒状态控制有重要影响。 初步研究 已经表明尼古丁会产生昼夜节律的强烈相移， 体外时钟这种对生物钟的影响将用啮齿动物来探索 模型来确定尼古丁诱导的相移的机制， 尼古丁是否能在体内和体外诱导昼夜节律。 需要考虑尼古丁的生物钟重置特性 充分了解吸烟的成瘾特征。 尼古丁发挥其作用的受体的药理学性质 将确定SCN中的效应，以及细胞内的 调节反应的机制。 将特别注意 α 7烟碱乙酰胆碱受体（nAChR）亚单位，即 在SCN内发现的唯一α亚基。这个新克隆的亚基 产生具有独特药理学的新型nAChR，包括高亲和力 α-银环蛇毒素（α-BTX）在卵母细胞中表达时。 这项工作 将主要在体外SCN切片制备中进行， 维持着神经元放电的昼夜节律 这种节奏强烈地 通过应用尼古丁改变，提供了一个理想的系统，其中 研究尼古丁作用的细节 尼古丁对整个动物生物钟的影响将是 在一个名为SCORE的自动化系统中进行检查，该系统可以测量 自发活动、饮水、进食、体温、EEG和其他 多种动物同时出现。 尼古丁能够 影响大鼠的昼夜节律可能与人类成瘾有关。 尼古丁成瘾的部分原因可能是一种 吸烟者的昼夜节律自我药物治疗，特别是为了增加吸烟者的觉醒， 早上吸烟实际上可以同步休息活动周期， 与光的样式相似，也许是互补的。尼古丁 另一方面，退出可能会导致这种损失。 在优选时钟唤醒时的同步和伴随的困难 在一个有时间意识的社会里，这肯定是一个令人厌恶的后果。 此外，戒烟者可能最容易再犯 一大早 该提案的最后一个具体目标是研究尼古丁对 胎儿SCN。最近的一份报告显示， 妊娠大鼠引起胎儿SCN中c-fos的特异性诱导， 增加了对发展中国家的 生物钟 初步证据表明， 尼古丁也有类似的作用。在这两种情况下，响应都发生在 胎儿，而不是成人。该提案将审查发展 尼古丁和可卡因的这种反应的变化，并调查 这一意外发现的可能解释。

The proposal is focused primarily on the effects of nicotine in the suprachiasmatic nucleus (SCN), locus of the circadian clock in mammals, and an important influence on arousal state control. Preliminary studies have shown that nicotine produces robust phase shifts of the circadian clock in vitro. This effect on the clock will be explored using a rodent model to determine the mechanisms of nicotine induced phase shifts and whether nicotine can entrain circadian rhythms both in vivo and in vitro. The clock resetting properties of nicotine need to be taken into account to fully understand the addictive characteristics of cigarette smoking. The pharmacological nature of the receptors at which nicotine exerts its effects in the SCN will be determined, as well as the intracellular mechanisms mediating the response. Particular attention will be paid to the alpha7 nicotinic acetylcholine receptor (nAChR) subunit, which is the only alpha subunit found within the SCN. This newly cloned subunit produces a novel nAChR with unique pharmacology, including high affinity for alpha-bungarotoxin (alpha-BTX) when expressed in oocytes. This work will be done primarily in the in vitro SCN slice preparation, which maintains a circadian rhythm of neuronal firing. This rhythm is strongly altered by the application of nicotine, providing an ideal System in which to examine the details of nicotine action. The effects of nicotine on the biological clock in whole animals will be examined in an automated system known as SCORE, which can measure locomotor activity, drinking, feeding, body temperature, EEG and other variables simultaneously from many animals. The ability of nicotine to entrain circadian rhythms in rats could have relevance to human addiction. Part of the addictive liability of nicotine may result from a kind of circadian self-medication in smokers, especially to augment arousal in the morning. Smoking may actually synchronize the rest-activity cycle in a fashion similar and perhaps complementary to that of light. Nicotine withdrawal, on the other hand, might result in the loss of such synchronization and concomitant difficulty in arousing at preferred clock times, surely an aversive consequence in a clock-conscious society. Furthermore, the smoker in withdrawal might be most prone to recidivism early in the morning. The final specific aim of this proposal examines the effect of nicotine on the fetal SCN. A recent report has shown that cocaine administration in pregnant rats causes a specific induction of c-fos in the fetal SCN, raising the possibility of deleterious effects on the developing biological clock. Preliminary evidence presented here suggests that nicotine has a similar effect. In both cases, the response occurs in the fetus but not in adults. This proposal will examine the developmental changes in this response for both nicotine and cocaine, and investigate possible explanations for this unexpected finding.