Department of Psychology, University of Guelph, Guelph, ON, N1G 2W1, Canada.
Collaborative Neuroscience Program, University of Guelph, Guelph, ON, Canada.
Psychopharmacology (Berl). 2021 Jun;238(6):1687-1701. doi: 10.1007/s00213-021-05803-0. Epub 2021 Mar 1.
Over the past decade, adolescent cigarette smoking has been declining. However, adolescent nicotine consumption via electronic cigarettes is rapidly gaining popularity. Earlier onset nicotine use is associated with increased risk of dependence. A bidirectional relationship between nicotine and stress exists; perceived stress is a predictor for nicotine use, and stress reduction is a commonly reported reason for using nicotine.
We assessed the prolonged impact of adolescent high-dose nicotine and/or footshock exposure on adult nicotine self-administration, anxiety-like behaviour, and hormonal responsivity.
During adolescence (postnatal day [P]28-56) male Sprague-Dawley rats were assigned to one of five groups: saline (SALPRE: 1 ml/kg, SC, every day), nicotine (NICPRE: 1 mg/kg, SC, alternating daily with saline; 14 total nicotine injections), footshock (SHOCKPRE: 8 of 0.5 s, 0.8 mA alternating sessions; saline every day), or combination nicotine and footshock (NIC+SHOCK: concurrent and alternating daily with saline, or NIC-SHOCK: alternating with saline on shock sessions). On P70, one cohort underwent spontaneous intravenous nicotine self-administration (0.03 mg/kg/infusion); another cohort was assessed for open-field behaviour (P71), then corticosterone (CORT) response to nicotine or footshock in adulthood (P72-73).
Intermittent adolescent nicotine or footshock alone (NICPRE and SHOCKPRE) did not potentiate adult spontaneous nicotine intake compared to SALPRE. However, both combination groups (NIC+SHOCK, NIC-SHOCK) showed increased adult nicotine consumption without associated differences in baseline anxiety-like behaviour or CORT response.
Adolescent nicotine and footshock stressors have a synergistic effect on adult nicotine consumption, enhancing nicotine intake. Avenues toward reducing stress in adolescent nicotine users may provide opportunities to reduce vulnerability to adult nicotine consumption.
在过去的十年中，青少年吸烟率有所下降。然而，青少年通过电子烟摄入尼古丁的现象却迅速流行起来。早期使用尼古丁会增加依赖的风险。尼古丁和压力之间存在双向关系；感知到的压力是使用尼古丁的预测因素，而减轻压力是报告使用尼古丁的常见原因。
我们评估了青少年大剂量尼古丁和/或足底电击暴露对成年后尼古丁自我给药、焦虑样行为和激素反应的长期影响。
在青春期（出生后第 28-56 天），雄性 Sprague-Dawley 大鼠被分为五组之一：盐水（SALPRE：1ml/kg，SC，每天一次）、尼古丁（NICPRE：1mg/kg，SC，每天交替注射盐水；共 14 次尼古丁注射）、足底电击（SHOCKPRE：8 次 0.5s，0.8mA 交替进行；每天注射盐水）或尼古丁和足底电击联合（NIC+SHOCK：同时或每天交替注射盐水，或 NIC-SHOCK：电击日交替注射盐水）。在 P70 时，一组大鼠接受了自发性静脉内尼古丁自我给药（0.03mg/kg/输注）；另一组大鼠进行了旷场行为评估（P71），然后在成年期（P72-73）评估了皮质酮（CORT）对尼古丁或足底电击的反应。
与 SALPRE 相比，青少年期间歇性尼古丁或足底电击单独作用（NICPRE 和 SHOCKPRE）并没有增强成年后自发性尼古丁摄入。然而，两组联合组（NIC+SHOCK、NIC-SHOCK）表现出成年后尼古丁摄入增加，但基础焦虑样行为或 CORT 反应没有差异。
青少年期尼古丁和足底电击应激源对成年后尼古丁消费具有协同作用，增加了尼古丁的摄入。在青少年尼古丁使用者中减少压力的途径可能为减少对成年尼古丁消费的易感性提供机会。
