Department of Psychiatry, University of Florida, 1149 Newell Dr., Gainesville, FL, 32611, USA.
Department of Pharmaceutics, University of Florida, Gainesville, USA.
Psychopharmacology (Berl). 2021 Mar;238(3):845-855. doi: 10.1007/s00213-020-05736-0. Epub 2021 Jan 7.
Systemic administration of the tobacco smoke constituent nicotine stimulates brain reward function in rats. However, it is unknown if the inhalation of tobacco smoke affects brain reward function.
These experiments investigated if exposure to smoke from high-nicotine SPECTRUM research cigarettes increases reward function and affects the rewarding effects of nicotine in adult male and female Wistar rats.
Reward function after smoke or nicotine exposure was investigated using the intracranial self-stimulation (ICSS) procedure. A decrease in reward thresholds reflects an increase in reward function. In the first experiment, the rats were exposed to tobacco smoke for 40 min/day for 9 days, and the rewarding effects of nicotine (0.03-0.6 mg/kg) were investigated 3 weeks later. In the second experiment, the dose effects of tobacco smoke exposure (40-min sessions, 1-4 cigarettes burnt simultaneously) on reward function were investigated.
Tobacco smoke exposure did not affect the nicotine-induced decrease in reward thresholds or response latencies in male and female rats. Smoke exposure lowered the brain reward thresholds to a similar degree in males and females and caused a greater decrease in latencies in females. There was a positive relationship between plasma nicotine and cotinine levels and the nicotine content of the SPECTRUM research cigarettes. Similar smoke exposure conditions led to higher plasma nicotine and cotinine levels in female than male rats.
These findings indicate that tobacco smoke exposure enhances brain reward function but does not potentiate the rewarding effects of nicotine in male and female rats.
系统给予吸烟烟雾成分尼古丁会刺激老鼠的大脑奖赏功能。然而，尚不清楚吸烟是否会影响大脑的奖赏功能。
这些实验调查了吸食高尼古丁含量的 SPECTRUM 研究香烟是否会增加奖赏功能，并影响成年雄性和雌性 Wistar 大鼠对尼古丁的奖赏效应。
使用颅内自我刺激（ICSS）程序来研究吸烟或尼古丁暴露后的奖赏功能。奖赏功能的增加表现为奖赏阈值的降低。在第一个实验中，大鼠每天暴露于吸烟环境 40 分钟，共 9 天，然后在 3 周后调查尼古丁（0.03-0.6mg/kg）的奖赏效应。在第二个实验中，研究了吸烟暴露（40 分钟/次，同时燃烧 1-4 支香烟）的剂量效应对奖赏功能的影响。
吸烟暴露并没有影响尼古丁诱导的雄性和雌性大鼠奖赏阈值或反应潜伏期的降低。吸烟暴露使雄性和雌性大鼠的大脑奖赏阈值降低到相似的程度，并使雌性大鼠的潜伏期降低得更多。血浆尼古丁和可替宁水平与 SPECTRUM 研究香烟中的尼古丁含量呈正相关。相似的吸烟暴露条件导致雌性大鼠的血浆尼古丁和可替宁水平高于雄性大鼠。
这些发现表明，吸烟暴露增强了大脑的奖赏功能，但不会增强雄性和雌性大鼠对尼古丁的奖赏效应。
