Department of Neuroscience; The Scripps Research Institute; La Jolla, CA, USA.
Department of Psychiatry, University of California, San Diego; La Jolla, CA, USA.
Nicotine Tob Res. 2024 May 22;26(6):715-723. doi: 10.1093/ntr/ntad211.
There has been a resurgence in nicotine inhalation in adolescents due to the popularity and availability of Electronic Nicotine Delivery Systems (ENDS). Almost five times as many US high-school seniors inhale nicotine vapor daily compared with those who smoke tobacco. This study was conducted to determine the impact of repeated adolescent vapor inhalation of nicotine on behavior in adulthood.
Male and female Sprague-Dawley rats were exposed to 30-minute sessions of ENDS vapor inhalation, twice daily, from post-natal day (PND) 31-40. Conditions included vapor from the propylene glycol (PG) vehicle or nicotine (30 mg/mL in the PG). Animals were assessed for effects of nicotine on open field (PND 74-105) and wheel activity (PND 126-180) and for volitional exposure to nicotine vapor (PND 285-395). Plasma nicotine and cotinine were assessed in separate groups of male and female Wistar and Sprague-Dawley rats after a single nicotine inhalation session.
Group mean plasma nicotine ranged from 39 to 59 ng/mL post-session with minimal strain differences detected. Adolescent nicotine exposure enhanced sensitivity to the locomotor stimulating effects of nicotine (0.1-0.8 mg/kg, s.c.) in an open field in female rats, but didn't change the effects of nicotine on wheel activity. Female rats exposed to nicotine (30 mg/mL) vapor as adolescents responded more vigorously than PG-exposed females to nicotine vapor in a fixed ratio 5 challenge.
Repeated adolescent nicotine vapor inhalation leads to enhanced liability for volitional exposure to nicotine vapor in adulthood in female rats, but minimal change in spontaneous locomotor behavior.
These results show that adolescent vaping of nicotine can lead to lasting sensitization to the effects of nicotine in adulthood, including volitional responding for nicotine vapor. Demonstration of this in a controlled animal model establishes causality in a manner not possible from longitudinal evidence in human populations. These findings further highlight the importance of decreasing adolescent nicotine exposure to e-cigarettes to reduce consumption in adulthood.
由于电子烟的普及和易得性，青少年对尼古丁吸入的兴趣再次高涨。与吸烟的美国高中生相比，现在每天有多达五倍的高年级学生吸入尼古丁蒸气。本研究旨在确定青少年反复吸入尼古丁蒸气对成年后行为的影响。
雄性和雌性 Sprague-Dawley 大鼠从出生后第 31-40 天开始，每天两次接受 30 分钟的电子烟蒸气吸入。处理条件包括来自丙二醇（PG）载体或尼古丁（PG 中 30mg/ml）的蒸气。在旷场（PND74-105）和轮动活动（PND126-180）以及自愿接触尼古丁蒸气（PND285-395）方面评估尼古丁对动物的影响。在单次尼古丁吸入后，在单独的雄性和雌性 Wistar 和 Sprague-Dawley 大鼠组中评估血浆尼古丁和可替宁。
组平均血浆尼古丁水平在给药后 39-59ng/ml 之间，检测到的株间差异最小。青春期尼古丁暴露增强了雌性大鼠对旷场中尼古丁（0.1-0.8mg/kg，sc）运动刺激作用的敏感性，但不改变尼古丁对轮动活动的影响。作为青少年接触尼古丁（30mg/ml）蒸气的雌性大鼠对尼古丁蒸气的固定比例 5 挑战的反应比 PG 暴露的雌性大鼠更强烈。
反复青少年尼古丁蒸气吸入会导致成年后对尼古丁蒸气的自愿暴露倾向增强，但自发性运动行为的变化最小。
这些结果表明，青少年吸食尼古丁会导致成年后对尼古丁作用的持久敏感，包括对尼古丁蒸气的自愿反应。在受控动物模型中证明这一点，以一种从人类群体的纵向证据不可能证明的方式确定了因果关系。这些发现进一步强调了减少青少年对电子烟的尼古丁暴露以减少成年后消费的重要性。
