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首页> 外文期刊>Pharmacology, Biochemistry and Behavior >The role of accumbens dopamine in lever pressing and response allocation: effects of 6-OHDA injected into core and dorsomedial shell.
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The role of accumbens dopamine in lever pressing and response allocation: effects of 6-OHDA injected into core and dorsomedial shell.

机译：伏安多巴胺在杠杆按压和反应分配中的作用：将6-OHDA注入核壳和背壳的作用。

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Three experiments investigated the behavioral effects of injections of the neurotoxic agent 6-hydroxydopamine (6-OHDA) into the core or shell of the nucleus accumbens. In the first experiment, it was observed that injections of 6-OHDA into either core or shell had no significant effect on variable interval 30-s responding. In Experiment 2, responding on a fixed ratio 5 (FR5) schedule was impaired by 6-OHDA injections in the core, but not the shell. Rats with core injections of 6-OHDA showed significant alterations in the relative distribution of interresponse times, which were indicative of reductions in the maximal rate of responding and increases in the number of pauses. In the third experiment, rats were tested using a lever-pressing/chow-feeding procedure, in which a preferred food (Bioserve pellets) was available by pressing a lever on a FR5 schedule, but a less preferred food (lab chow) was also available concurrently in the test chamber. Untreated rats usually pressed the lever at high rates to obtain the food pellets and ate little of the lab chow. After training, dopamine depletions were produced by injections of 6-OHDA directly into the core or dorsomedial shell subregions. Injections of 6-OHDA into the core significantly decreased lever pressing for food pellets, increased lab chow consumption, and decreased the relative amount of food obtained by lever pressing. Dorsomedial shell injections of 6-OHDA had no significant effects on either lever pressing or lab chow consumption. Neurochemical results indicate that injections of 6-OHDA in the shell produced substantial depletions in the shell that were somewhat selective; however, injections of 6-OHDA into the core tended to deplete both core and shell. Correlational analyses revealed that decreases in FR5 lever pressing were associated with dopamine levels in the core, but not the shell. The present results indicate that substantial depletions of dopamine in the dorsomedial shell are not sufficient for suppressing reinforced lever pressing, and indicate that dopamine depletions must include the core area to impair performance on these tasks. The lack of effect of accumbens dopamine depletions on VI30 responding are consistent with the notion that accumbens dopamine depletions affect responding on schedules that generate a high rate of responding (FR5), but not those that generate a moderate rate of responding (e.g., VI30 s). The results of the concurrent FR5/chow-feeding experiment indicate that rats with accumbens dopamine depletions remain directed towards the acquisition and consumption of food. These results suggest that dopamine in the core region of accumbens sets constraints upon the selection of food-related behaviors, and that core dopamine depletions alter the relative allocation of food-related responses.
机译：三个实验研究了将神经毒性剂6-羟基多巴胺（6-OHDA）注射到伏伏核的核或壳中的行为影响。在第一个实验中，观察到向核或壳中注入6-OHDA对可变间隔30-s反应没有显着影响。在实验2中，在内核中而不是在外壳中进行6-OHDA注入会削弱对固定比率5（FR5）计划的响应。核心注射6-OHDA的大鼠在相互反应时间的相对分布中显示出显着变化，这表明最大反应速率降低且停顿次数增加。在第三个实验中，使用杠杆按压/喂食程序对大鼠进行了测试，其中可以通过按FR5时间表按压杠杆来获得首选食物（Bioserve颗粒），但是还提供了次优食物（实验室食物）可同时在测试室中使用。未经治疗的老鼠通常以很高的速度按下杠杆以获取食物颗粒，并且很少吃实验室食物。训练后，通过将6-OHDA直接注入核或背壳壳子区域产生多巴胺消耗。向芯中注入6-OHDA可以显着减少食品颗粒的杠杆压榨，增加实验室食物消耗并减少通过杠杆压榨获得的相对食物量。 6-OHDA的背壳注射对杠杆按压或实验室食物的消耗均无明显影响。神经化学结果表明，在壳中注射6-OHDA会在壳中产生大量的损耗，而这种损耗有些选择性。然而，向核中注入6-OHDA往往会耗尽核和壳。相关分析表明，FR5杠杆受压的降低与核中的多巴胺水平有关，而与壳中的多巴胺水平无关。目前的结果表明，在背壳中大量消耗多巴胺不足以抑制增强的杠杆压迫，并且表明，消耗多巴胺必须包括核心区域，以削弱这些任务的性能。伏安多巴胺耗竭对VI30响应缺乏影响的观点与伏安多巴胺耗竭影响按计划产生高响应率（FR5）而不是按计划产生中度响应率的​​人（例如VI30 ）。同时进行的FR5 /低脂喂养实验的结果表明，具有精确多巴胺消耗的大鼠仍然直接用于食物的获取和消费。这些结果表明，伏隔区核心区域的多巴胺对食物相关行为的选择设置了约束，核心多巴胺的消耗改变了食物相关反应的相对分配。

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