BACKGROUND Adolescent nicotine exposure increases methamphetamine (MA) intake in adult male rats; however, little is known about how nicotine affects MA self-administration during the adolescent period. Therefore, we assessed whether exposing rats to nicotine during early or late adolescence affects oral MA self-administration. METHODS 146 male and female rats were treated with saline or nicotine (0.16 or 0.64 mg/kg) from postnatal day (PD) 25-PD 34 (the early exposure phase) and/or PD 35-PD 55 (the late exposure phase). Rats began an oral MA self-administration procedure on PD 35. RESULTS Only the sex variable, but not nicotine, affected sucrose and MA acquisition, as female rats had more nose pokes than males during training. On the test sessions, female rats exposed to nicotine (0.64 mg/kg) in the early exposure phase had more active nose pokes than saline-treated female rats or nicotine-treated male rats. Rats exposed to nicotine (0.16 mg/kg) in the late exposure phase had fewer active nose pokes during testing than rats exposed to saline. Nose poke responding during extinction was not altered by nicotine exposure, but administering nicotine (0.16 or 0.64 mg/kg) to male rats in the early exposure phase did decrease nose pokes during the drug-primed reinstatement session. CONCLUSIONS Our results show that adolescent female rats are more sensitive to the reinforcing effects of oral sucrose and MA than adolescent males, and that preadolescent nicotine exposure enhances oral MA self-administration in female rats. These findings suggest that preteen nicotine use may increase vulnerability to later MA abuse in teenage girls.

中文翻译：

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烟碱暴露对青春期雌雄大鼠口服甲基苯丙胺自我给药，消退和药物引发的恢复作用的影响。

背景青春期尼古丁暴露会增加成年雄性大鼠的甲基苯丙胺（MA）摄入量。然而，关于尼古丁如何影响青少年期MA自我管理的知之甚少。因此，我们评估了青春期早期或晚期将大鼠暴露于尼古丁会影响口服MA的自我给药。方法146只雄性和雌性大鼠从出生后（PD）25-PD 34（早期暴露阶段）和/或PD 35-PD 55（晚期暴露阶段）开始接受生理盐水或尼古丁（0.16或0.64 mg / kg）治疗。大鼠在PD 35上开始口服MA自我管理程序。结果仅性别变量影响蔗糖和MA摄取，而尼古丁则不受影响，因为在训练过程中雌性大鼠的鼻po多于雄性。在测试阶段，雌性大鼠暴露于尼古丁（0。暴露于早期阶段（64 mg / kg）的鼻子nose声比生理盐水处理的雌性大鼠或尼古丁处理的雄性大鼠多。在暴露后期，暴露于尼古丁（0.16 mg / kg）的大鼠与暴露于盐水的大鼠相比，在测试过程中活动鼻po更少。尼古丁暴露并没有改变灭绝过程中的鼻oke反应，但是在早期暴露阶段向雄性大鼠施用烟碱（0.16或0.64 mg / kg）确实在药物引发的恢复期中减少了鼻po。结论我们的结果表明，青春期雌性大鼠对口服蔗糖和MA的增强作用比青春期雄性更敏感，并且青春期前尼古丁暴露可增强雌性大鼠口服MA的自我给药。这些发现表明，青春期前使用尼古丁可能增加少女对后来的MA滥用的脆弱性。