Levine Allen S, Kotz Catherine M, Gosnell Blake A
Minnesota Obesity Center, Minneapolis VA Medical Center, Minneapolis, MN 55417, USA.
Am J Clin Nutr. 2003 Oct;78(4):834S-842S. doi: 10.1093/ajcn/78.4.834S.
The prevalence of obesity has increased dramatically in recent years in the United States, with similar patterns seen in several other countries. Although there are several potential explanations for this dramatic increase in obesity, dietary influences are a contributing factor. An inverse correlation between dietary sugar intake and body mass index has been reported, suggesting beneficial effects of carbohydrate intake on body mass index. In this review we discuss how sugars interact with regulatory neurochemicals in the brain to affect both energy intake and energy expenditure. These neurochemicals appear to be involved in dietary selection, and sugars and palatable substances affect neurochemical changes in the brain. For example, rats that drink sucrose solutions for 3 wk have major changes in neuronal activity in the limbic area of the brain, a region involved in pleasure and other emotions. We also investigate the relations between sucrose (and other sweet substances), drugs of abuse, and the mesolimbic dopaminergic system. The presence of sucrose in an animal's cage can affect the animals desire to self-administer drugs of abuse. Also, an animal's level of sucrose preference can predict its desire to self-administer cocaine. Such data suggest a relation between sweet taste and drug reward, although the relevance to humans is unclear. Finally, we address the influence of sugar on body weight control. For example, sucrose feeding for 2 wk decreases the efficiency of energy utilization and increases gene expression of uncoupling protein 3 in muscle, suggesting that sucrose may influence uncoupling protein 3 activity and contribute to changes in metabolic efficiency and thus regulation of body weight.
近年来，美国肥胖症的患病率急剧上升，其他几个国家也出现了类似的情况。虽然肥胖症急剧增加有多种潜在原因，但饮食影响是一个促成因素。据报道，饮食中糖的摄入量与体重指数呈负相关，这表明碳水化合物摄入对体重指数有有益影响。在这篇综述中，我们讨论糖如何与大脑中的调节神经化学物质相互作用，以影响能量摄入和能量消耗。这些神经化学物质似乎参与了饮食选择，糖和美味物质会影响大脑中的神经化学变化。例如，连续3周饮用蔗糖溶液的大鼠，其大脑边缘区域（一个与愉悦和其他情绪有关的区域）的神经元活动会发生重大变化。我们还研究了蔗糖（和其他甜味物质）、滥用药物与中脑边缘多巴胺能系统之间的关系。动物笼中蔗糖的存在会影响动物自我给药滥用药物的欲望。此外，动物对蔗糖的偏好程度可以预测其自我给药可卡因的欲望。尽管与人类的相关性尚不清楚，但这些数据表明甜味与药物奖赏之间存在关联。最后，我们探讨了糖对体重控制的影响。例如，连续2周喂食蔗糖会降低能量利用效率，并增加肌肉中解偶联蛋白3的基因表达，这表明蔗糖可能会影响解偶联蛋白3的活性，并导致代谢效率的变化，从而影响体重调节。
