Preferential increase of extracellular dopamine in the rat nucleus accumbens shell as compared to that in the core during acquisition and maintenance of intravenous nicotine self-administration
Preferential increase of extracellular dopamine in the rat nucleus accumbens shell as compared to that in the core during acquisition and maintenance of intravenous nicotine self-administration
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DOI：
10.1007/s00213-005-0280-4
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发表时间：
2006-02-01
影响因子：
3.4
通讯作者：
Di Chiara, G
中科院分区：
文献类型：
--
作者：
Lecca, D;Cacciapaglia, F;Di Chiara, G
理由：据报道，与伏隔核（NAc）的核心相比，被动给药尼古丁优先增加壳细胞外多巴胺（DA）的释放。到目前为止，还没有信息表明这是否也适用于主动的、反应性的尼古丁给药。目的：观察主动静脉给药（SA）过程中NAc壳和核细胞外DA的变化。方法：双侧植入慢性插管，训练大鼠自我给药（0.03 mg/kg，静脉滴注），每日1 h单次，持续6周，初始固定比（FR） 1增加至FR 2。在SA开始前和开始后90min监测NAc壳和核心的透析液DA。结果：从第16次SA开始，活跃的鼻子比不活跃的鼻子明显增加。NAc亚型的基底细胞外DA没有差异。数据分析显示：(1)在尼古丁胁迫期间，NAc分支的透析液DA显著高于基础水平，从壳内第1周开始，从核内第2周开始；(2)在尼古丁胁迫期间，细胞外DA在壳内优先增加（24-43%），而在核内优先增加（10-23%）；(3)NAc分支的透析液DA在灭绝期间没有变化。结论：与尼古丁暴露的持续时间无关，反应型尼古丁SA优先增加NAc外壳的DA输出，而不是核心。NAc - DA的增加与尼古丁作用密切相关，因为尽管有主动反应，但在消失过程中没有观察到。
Rationale: It has been reported that passive administration of nicotine increases preferentially extracellular dopamine (DA) release in the shell as compared to that in the core of the nucleus accumbens (NAc). To date, no information is available if this also applies to active, response-contingent nicotine administration. Objective: This study was aimed to monitor the changes of extracellular DA in the NAc shell and core during active intravenous nicotine self-administration (SA). Methods: Rats were bilaterally implanted with chronic cannulae and were trained to self-administer nicotine (0.03 mg/kg, i.v.) in single daily 1-h session for 6 weeks, with an initial fixed ratio (FR) 1 schedule increased to FR 2. Dialysate DA from the NAc shell and core was monitored before and for 90 min after the start of SA. Results: Significant increases of active nose-pokes over inactive ones were found starting from the 16th SA session. No differences were found in basal extracellular DA in the NAc subdivisions. Data analysis showed (1) significant increases over basal of dialysate DA in the NAc subdivisions during nicotine SA, starting from the first week in the shell and from the second week in the core, (2) preferential increase of extracellular DA during nicotine SA in the shell (24-43%) compared to that in the core (10-23%) and (3) no change in dialysate DA in NAc subdivisions during extinction. Conclusions: Response-contingent nicotine SA preferentially increases the DA output in the NAc shell as compared to that in the core, independently from the duration of the nicotine exposure. Increase in NAc DA is strictly related to nicotine action since is not observed during extinction in spite of active responding.