Systems neuroscience: the stress of dieting.

摘要

Many readers will have experienced that it is all too easy to regain the weight lost after a diet, and that experiencing stress somehow makes high-calorie foods particularly tempting. Bale and colleagues now provide a link between yo-yo dieting and stress by showing that in mice, food restriction alters stress and feeding pathways in the brain, and promotes binge eating of high-fat foods upon subsequent exposure to stress. The authors used a mouse model of moderate caloric restriction that produces a 10-15% reduction in body weight. They found that 3 weeks of food restriction sensitized the hypothalamus-pituitary-adrenal stress axis: calorie-restricted mice had higher basal corticosterone levels and increased corticosterone release in response to restraint stress compared with control mice. Interestingly, expression of the gene encoding corticotrophin-releasing factor (Crf) in the bed nucleus of the stria terminals (BNST) - a brain area where stress and reward pathways intersect - was decreased after caloric restriction and did not return to normal after chow re-feeding. In accordance with this finding, methylation of the Crf promotor was decreased in the BNST and remained so after re-feeding. In a different diet model, withdrawal from a high-fat diet had similar effects on Crf expression and methylation patterns.