Grimm Jeffrey W, Barnes Jesse, North Kindsey, Collins Stefan, Weber Rachel
Department of Psychology and Program in Behavioral Neuroscience, Western Washington University, USA.
J Vis Exp. 2011 Nov 4(57):e3335. doi: 10.3791/3335.
For someone on a food-restricted diet, food craving in response to food-paired cues may serve as a key behavioral transition point between abstinence and relapse to food taking. Food craving conceptualized in this way is akin to drug craving in response to drug-paired cues. A rich literature has been developed around understanding the behavioral and neurobiological determinants of drug craving; we and others have been focusing recently on translating techniques from basic addiction research to better understand addiction-like behaviors related to food. As done in previous studies of drug craving, we examine sucrose craving behavior by utilizing a rat model of relapse. In this model, rats self-administer either drug or food in sessions over several days. In a session, lever responding delivers the reward along with a tone+light stimulus. Craving behavior is then operationally defined as responding in a subsequent session where the reward is not available. Rats will reliably respond for the tone+light stimulus, likely due to its acquired conditioned reinforcing properties. This behavior is sometimes referred to as sucrose seeking or cue reactivity. In the present discussion we will use the term "sucrose craving" to subsume both of these constructs. In the past decade, we have focused on how the length of time following reward self-administration influences reward craving. Interestingly, rats increase responding for the reward-paired cue over the course of several weeks of a period of forced-abstinence. This "incubation of craving" is observed in rats that have self-administered either food or drugs of abuse. This time-dependent increase in craving we have identified in the animal model may have great potential relevance to human drug and food addiction behaviors. Here we present a protocol for assessing incubation of sucrose craving in rats. Variants of the procedure will be indicated where craving is assessed as responding for a discrete sucrose-paired cue following extinction of lever pressing within the sucrose self-administration context (Extinction without cues) or as responding for sucrose-paired cues in a general extinction context (Extinction with cues).
对于遵循限食饮食的人来说，对与食物相关线索产生的食物渴望可能是禁食和恢复进食之间关键的行为转变点。以这种方式概念化的食物渴望类似于对与药物相关线索产生的药物渴望。围绕理解药物渴望的行为和神经生物学决定因素已经形成了丰富的文献；我们和其他人最近一直专注于将基础成瘾研究中的技术应用于更好地理解与食物相关的成瘾样行为。正如之前对药物渴望的研究所做的那样，我们通过使用复发大鼠模型来研究蔗糖渴望行为。在这个模型中，大鼠在几天的实验过程中自行给药药物或食物。在一次实验中，按压杠杆会伴随着音调 + 灯光刺激给予奖励。然后，渴望行为在操作上被定义为在随后一次没有奖励的实验中的反应。大鼠会可靠地对音调 + 灯光刺激做出反应，这可能是由于其获得的条件强化特性。这种行为有时被称为蔗糖寻求或线索反应性。在本讨论中，我们将使用术语“蔗糖渴望”来涵盖这两种结构。在过去十年中，我们专注于奖励自我给药后的时间长度如何影响奖励渴望。有趣的是，在强制禁欲的几周时间里，大鼠对与奖励相关线索的反应会增加。这种“渴望的潜伏期”在自行给药食物或滥用药物的大鼠中都能观察到。我们在动物模型中确定的这种随时间增加的渴望可能与人类药物和食物成瘾行为有很大的潜在相关性。在这里，我们提出了一种评估大鼠蔗糖渴望潜伏期的方案。当在蔗糖自我给药环境中杠杆按压消退后对离散的与蔗糖相关线索的反应（无线索消退）或在一般消退环境中对与蔗糖相关线索的反应（有线索消退）来评估渴望时，将指出该程序的变体。
