Appetitive behaviours in rats: routes to addiction?

在人类和动物中，是什么开始和停止了积极动机和食欲行为的发生，我们还没有得到很好的理解。目前还不清楚这些行为如何以及为什么会受到干扰。尽管我们缺乏理解，但这些令人不安的食欲行为（例如，吸毒成瘾和饮食失调）及其后果（例如肥胖）是主要的健康问题。动物模型有助于阐明这些行为的生物学和心理学方面。根据动物研究，获取条件似乎在过度行为表达的发展中起着重要作用。我正在探索大鼠两种食欲行为的模式和相互作用；糖溶液消耗和车轮运转。每天长6小时接近车轮导致高水平的运行，但短1小时的访问没有。连续摄入糖比每隔三天摄入糖要低得多。幼鼠可以自愿（在6小时内）跑超过2.5公里，并且间歇性地每天可以喝300克以上的4%糖溶液（正常的水消耗量约为40克）。通过研究这两种行为成瘾，并将它们与我们所知道的其他成瘾模型（如老鼠的药物自我给药）进行比较，可能证明有可能阐明导致过渡到过度消费水平的关键变量。通过确定药物成瘾的特征是否也适用于这两种食欲行为，我们将能够证明，类似成瘾的模式可以发生在许多食欲行为中。这表明成瘾是一种源于自然食欲行为的东西。更好地了解导致老鼠过度消费的因素可能会为人类成瘾提供线索，提示脆弱的警告信号，并可能提出治疗建议。

What starts and stops the occurrence of positively motivated, appetitive behaviours in people and animals is not well understood. It is also not clear how and why these behaviours become disturbed. Despite our lack of understanding, these disturbed appetitive behaviours (for example, drug addiction and eating disorders) and their consequences (such as obesity) are major health problems. Animal models help clarify biological and psychological aspects of these behaviours. Based on work with animal studies it appears access conditions play an important role in the development of excessive behaviour expression. I am exploring the pattern of and interactions of two appetitive behaviours in rats; sugar solution consumption and wheel running. Daily long 6 h access to wheels results in high levels of running but short 1 h access does not. Continuous access to sugar results in much lower consumption than does every third day access. Young rats can voluntarily come to run (in 6 h) over 2.5 km, and with intermittent access can drink over 300 g of a 4% sugar solution a day (normal water consumption is about 40 g). By studying these two behavioural addictions and comparing them to what we know about other addiction models, like drug self-administration in rats, it may prove possible to elucidate the critical variables responsible for the transition to excessive levels of consumption. By determining if the characteristics of drug addiction also apply to these two appetitive behaviours we will be able to argue that addiction-like patterns can occur with many appetitive behaviours. This would suggest that addiction is something that has roots in natural appetitive behaviours. A better understanding of factors responsible for the transition to excessive consumption in rats may provide clues to human addiction, suggest warning signs for vulnerability, and could lead to suggestions for treatment.