Nesil Tanseli, Kanit Lutfiye, Pogun Sakire
Ege University, Center for Brain Research, Bornova, Izmir, Turkey.
Ege University, Center for Brain Research, Bornova, Izmir, Turkey; Ege University, School of Medicine, Department of Physiology, Bornova, Izmir, Turkey.
Pharmacol Biochem Behav. 2015 Nov;138:156-63. doi: 10.1016/j.pbb.2015.10.001. Epub 2015 Oct 3.
Nicotine is the major addictive component in tobacco, and despite well-established adverse health effects of tobacco addiction, some smokers have difficulty quitting. The acute cognitive enhancement and/or the amelioration of the cognitive disruption during withdrawal that some smokers experience after smoking are among important factors that hinder quit attempts. The animal model presented in the current study is comparable to the human smoking condition although nicotine intake routes are different. Rats were exposed to a free choice of oral nicotine starting at adolescence, and given a water maze (WM) task as adults. This design allowed us to see if rats alter their nicotine intake during the WM task and if nicotine preference and intake modify abilities and strategies rats use for problem solving.
Male and female rats were exposed to a free choice of oral nicotine/water for 24weeks, starting at five weeks of age. After this period, they were selected based on their nicotine intake and, together with control animals that received only water, were subjected to a place-learning task in the WM. Free-choice nicotine exposure continued during WM testing. Following acquisition, the probe trial presented the rats with a choice between using two different strategies for problem solving.
Nicotine supported acquisition and rats increased their nicotine intake during WM testing; this effect was more pronounced in male rats with minimum nicotine preference and intake. Furthermore, nicotine modified the "female type" strategy in solving the place-learning task and nicotine treated female rats, unlike control females, behaved like males.
The increase in nicotine intake during mental engagement, and the sexually dimorphic effect of nicotine on problem solving strategies that we have observed in rats, may suggest that implementing sex-specific smoking cessation approaches, especially under stressful and cognitively demanding conditions, may be useful in helping smokers quit.
尼古丁是烟草中的主要成瘾成分，尽管烟草成瘾对健康有明确的不良影响，但一些吸烟者仍难以戒烟。一些吸烟者在吸烟后所经历的急性认知增强和/或戒断期间认知紊乱的改善是阻碍戒烟尝试的重要因素。尽管尼古丁摄入途径不同，但本研究中提出的动物模型与人类吸烟情况具有可比性。大鼠从青春期开始可自由选择口服尼古丁，并在成年后接受水迷宫（WM）任务。这种设计使我们能够观察大鼠在WM任务期间是否改变其尼古丁摄入量，以及尼古丁偏好和摄入量是否会改变大鼠用于解决问题的能力和策略。
雄性和雌性大鼠从5周龄开始可自由选择口服尼古丁/水，持续24周。在此期间后，根据它们的尼古丁摄入量进行选择，并与仅接受水的对照动物一起在WM中进行位置学习任务。在WM测试期间继续自由选择尼古丁暴露。在习得后，探针试验让大鼠在使用两种不同策略解决问题之间进行选择。
尼古丁有助于习得，并且大鼠在WM测试期间增加了尼古丁摄入量；这种效应在尼古丁偏好和摄入量最低的雄性大鼠中更为明显。此外，尼古丁改变了在解决位置学习任务中的“雌性类型”策略，与对照雌性不同，尼古丁处理的雌性大鼠表现得像雄性。
我们在大鼠中观察到，在精神活动期间尼古丁摄入量增加，以及尼古丁对解决问题策略的性别差异效应，可能表明实施针对性别的戒烟方法，尤其是在压力大和认知要求高的情况下，可能有助于吸烟者戒烟。
