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Abstract：
BACKGROUND: 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.
OBJECTIVE: 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.
METHODS: 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.
RESULTS: 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.
CONCLUSIONS: 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.
OBJECTIVE: 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.
METHODS: 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.
RESULTS: 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.
CONCLUSIONS: 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.
摘要：
背景：全身施用烟草烟雾成分尼古丁刺激大鼠的脑奖励功能。然而,目前尚不清楚烟草烟雾的吸入是否会影响大脑的奖励功能。
目的：这些实验研究了暴露于高尼古丁SPECTRUM研究香烟的烟雾是否会增加成年雄性和雌性Wistar大鼠的奖励功能并影响尼古丁的奖励作用。
方法：使用颅内自我刺激（ICSS）程序研究烟雾或尼古丁暴露后的奖励功能。奖励阈值的降低反映了奖励函数的增加。在第一个实验中,大鼠暴露于烟草烟雾40分钟/天，持续9天，3周后研究了尼古丁（0.03-0.6mg/kg）的奖励作用。在第二个实验中,烟草烟雾暴露的剂量效应(40分钟，1-4支香烟同时燃烧）对奖励功能进行了研究。
结果：烟草烟雾暴露并不影响尼古丁诱导的雄性和雌性大鼠的奖励阈值或反应潜伏期的降低。烟雾暴露使男性和女性的大脑奖励阈值降低到相似的程度，并导致女性的潜伏期减少。血浆尼古丁和可替宁水平与SPECTRUM研究香烟的尼古丁含量之间存在正相关关系。类似的烟雾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。
结论：这些发现表明，烟草烟雾暴露可增强雄性和雌性大鼠的大脑奖励功能，但不能增强尼古丁的奖励作用。
目的：这些实验研究了暴露于高尼古丁SPECTRUM研究香烟的烟雾是否会增加成年雄性和雌性Wistar大鼠的奖励功能并影响尼古丁的奖励作用。
方法：使用颅内自我刺激（ICSS）程序研究烟雾或尼古丁暴露后的奖励功能。奖励阈值的降低反映了奖励函数的增加。在第一个实验中,大鼠暴露于烟草烟雾40分钟/天，持续9天，3周后研究了尼古丁（0.03-0.6mg/kg）的奖励作用。在第二个实验中,烟草烟雾暴露的剂量效应(40分钟，1-4支香烟同时燃烧）对奖励功能进行了研究。
结果：烟草烟雾暴露并不影响尼古丁诱导的雄性和雌性大鼠的奖励阈值或反应潜伏期的降低。烟雾暴露使男性和女性的大脑奖励阈值降低到相似的程度，并导致女性的潜伏期减少。血浆尼古丁和可替宁水平与SPECTRUM研究香烟的尼古丁含量之间存在正相关关系。类似的烟雾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。
结论：这些发现表明，烟草烟雾暴露可增强雄性和雌性大鼠的大脑奖励功能，但不能增强尼古丁的奖励作用。
