MOLECULAR APPROACHES TO DRUGS OF ABUSE AND AROUSAL STATE

该提案主要关注尼古丁对人体健康的影响。 视交叉上核(SCN)，哺乳动物昼夜节律钟的位置， 对唤醒状态控制也有重要影响。初步研究 已经证明尼古丁会引起昼夜节律的强烈相移 体外时钟。这种对时钟的影响将通过一只啮齿动物来探索。 确定尼古丁诱导相移机制的模型 尼古丁是否在体内和体外都能引起昼夜节律。 需要考虑尼古丁的时钟重置特性 充分了解吸烟的成瘾特点。 尼古丁作用于受体的药理学性质 将确定SCN中的影响以及细胞内的 调节反应的机制。我们将特别注意 α7烟碱型乙酰胆碱受体(NAChR)亚单位，是 只有在SCN中发现了阿尔法亚单位。这个新克隆的亚基 产生一种具有独特药理的新型nAChR，包括高亲和力 当α-银环蛇毒素(α-BTX)在卵母细胞中表达时。这部作品 将主要在体外进行SCN切片的制备，其中 维持神经元放电的昼夜节律。这种节奏很强烈 通过尼古丁的应用改变，提供了一个理想的系统，在其中 来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 活动、饮酒、进食、体温、脑电等 同时来自许多动物的变量。尼古丁的能力 大鼠体内的昼夜节律可能与人类成瘾有关。 尼古丁的部分成瘾倾向可能是由于一种 吸烟者的昼夜自我用药，尤其是为了增强吸烟者的觉醒。 早上。吸烟实际上可能会使休息-活动周期同步在一个 时尚与光相似，或许是互补的。尼古丁 另一方面，撤军可能会导致这种损失 在首选时钟唤醒时的同步和伴随的困难 在一个有时钟意识的社会里，时代无疑是一个令人厌恶的后果。 此外，戒烟期间的吸烟者可能最容易再次犯罪。 一大早。 这项提案的最后一个具体目标是检查尼古丁对 胎儿的SCN。最近的一份报告显示，在美国，服用可卡因 怀孕的大鼠导致胎儿SCN中c-fos的特异性诱导， 增加了对发展产生有害影响的可能性 生物钟。这里提出的初步证据表明 尼古丁也有类似的效果。在这两种情况下，响应都发生在 胎儿，但不是成人。这项提案将审查发展的 尼古丁和可卡因的这种反应的变化，并调查 对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.