Appetitive behaviours in rats: routes to addiction?

人类和动物的积极动机和食欲行为的开始和停止还没有被很好地理解。目前也不清楚这些行为是如何以及为什么受到干扰的。尽管我们缺乏了解，但这些受干扰的食欲行为(例如，吸毒和饮食失调)及其后果(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。根据对动物的研究，接触条件似乎在过度行为表达的发展中起着重要作用。我正在探索老鼠两种食欲行为的模式和相互作用：糖水摄入和车轮跑步。每天长时间接触车轮6小时会导致高水平的跑步，但短时间接触1小时则不会。与每隔三天摄入一次糖相比，连续摄入糖分的消费量要低得多。幼鼠可以自愿跑(6小时内)超过2.5公里，断断续续地跑一天可以喝超过300克4%的糖溶液(正常用水量约为40克)。通过研究这两种行为成瘾，并将它们与我们所知的其他成瘾模型进行比较，例如大鼠的药物自我给药，可能会证明有可能阐明导致过度消费水平转变的关键变量。通过确定药物成瘾的特征是否也适用于这两种食欲行为，我们将能够论证，在许多食欲行为中可能会出现类似成瘾的模式。这表明，上瘾源于自然的食欲行为。更好地了解导致老鼠过渡到过度摄入的因素，可能会为人类成瘾提供线索，为脆弱提供警告信号，并可能导致治疗建议。

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.