Nandrolone, an anabolic androgenic steroid, is included in the prohibited list of the World Anti-Doping Agency. Drugs of abuse activate brain dopamine neurons and nandrolone has been suspected of inducing dependence. Accordingly, possible critical periods for the effects of nandrolone on muscular strength and dopaminergic activity have been investigated, including the effects of chronically administered nandrolone alone and on morphine-induced increases in dopamine efflux in the nucleus accumbens. Six- or 10-week-old male Sprague-Dawley rats were used. Treatment with nandrolone was initiated in adolescent (6-week-old) and young adult (10-week-old) rats. Nandrolone (5.0 mg/kg s.c.) or sesame oil vehicle was given once daily, on six consecutive days per week, for 3 weeks and then once per day for 4 consecutive days. Nandrolone enhanced the developmental increase in grip strength of 6- but not 10-week-old rats, without altering the developmental increase in body weight of either age group. Using in vivo microdialysis in freely moving 6-week-old rats given nandrolone for 4 weeks, basal accumbal dopamine efflux was unaltered, while the increase in dopamine efflux induced by acute administration of morphine (1.0 mg/kg s.c.) was reduced. The present study provides in vivo evidence that adolescence constitutes a critical period during which repeated administration of nandrolone enhances increases in muscular strength without influencing increases in body weight. Though repeated administration of nandrolone during this period of adolescence did not stimulate in vivo mesolimbic dopaminergic activity, it disrupted stimulation by an opioid, the drug class that is most commonly coabused with nandrolone.

中文翻译：

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青春期是诺龙诱导的肌肉力量与滥用倾向相关的关键时期，单独使用或与吗啡联合使用，在自由活动的大鼠中使用累积多巴胺流出

诺龙是一种合成代谢类固醇，被列入世界反兴奋剂机构的禁用名单。滥用药物会激活大脑多巴胺神经元，诺龙被怀疑会诱发依赖性。因此，已经研究了诺龙对肌肉力量和多巴胺能活动影响的可能关键时期，包括单独长期服用诺龙的影响和吗啡诱导的伏隔核中多巴胺外流增加的影响。使用 6 周或 10 周大的雄性 Sprague-Dawley 大鼠。在青春期（6 周龄）和年轻成年（10 周龄）大鼠中开始使用诺龙治疗。诺龙 (5.0 mg/kg sc) 或芝麻油载体每天一次，每周连续六天，持续 3 周，然后每天一次，连续 4 天。Nandrolone 增强了 6 周大但不是 10 周大大鼠握力的发育增加，而没有改变任一年龄组体重的发育增加。在给予诺龙酮 4 周的自由活动的 6 周龄大鼠中使用体内微透析，基础累积多巴胺流出没有改变，而急性给予吗啡 (1.0 mg/kg sc) 诱导的多巴胺流出增加减少。本研究提供了体内证据，表明青春期是一个关键时期，在此期间重复服用诺龙可以增强肌肉力量而不影响体重的增加。虽然在这个青春期反复服用诺龙并没有刺激体内中脑边缘多巴胺能活动，但它破坏了阿片类药物的刺激，