http://academic.oup.com/milmed/article-pdf/146/7/506/24126715/milmed-146-7-506.pdf

Goodman and Gilman's The Pharmacological Basis of Therapeutics

Food intake is regulated by the hypothalamus, including the melanocortin and neuropeptide Y (NPY) systems in the arcuate nucleus. The NPY Y2 receptor (Y2R), a putative inhibitory presynaptic receptor, is highly expressed on NPY neurons in the arcuate nucleus, which is accessible to peripheral hormones. Peptide YY3-36 (PYY3-36), a Y2R agonist, is released from the gastrointestinal tract postprandially in proportion to the calorie content of a meal. Here we show that peripheral injection of PYY3-36 in rats inhibits food intake and reduces weight gain. PYY3-36 also inhibits food intake in mice but not in Y2r-null mice, which suggests that the anorectic effect requires the Y2R. Peripheral administration of PYY3-36 increases c-Fos immunoreactivity in the arcuate nucleus and decreases hypothalamic Npy messenger RNA. Intra-arcuate injection of PYY3-36 inhibits food intake. PYY3-36 also inhibits electrical activity of NPY nerve terminals, thus activating adjacent pro-opiomelanocortin (POMC) neurons. In humans, infusion of normal postprandial concentrations of PYY3-36 significantly decreases appetite and reduces food intake by 33% over 24 h. Thus, postprandial elevation of PYY3-36 may act through the arcuate nucleus Y2R to inhibit feeding in a gut–hypothalamic pathway.

BRIEF COMMUNICATION ARISING: Gut hormone PYY3-36 physiologically inhibits food intake

Inhibition and impulsivity: Behavioral and neural basis of response control

Given assertions of the theoretical, empirical, and practical importance of self-control, this meta-analytic study sought to review evidence concerning the relationship between dispositional self-control and behavior. The authors provide a brief overview over prominent theories of self-control, identifying implicit assumptions surrounding the effects of self-control that warrant empirical testing. They report the results of a meta-analysis of 102 studies (total N = 32,648) investigating the behavioral effects of self-control using the Self-Control Scale, the Barratt Impulsiveness Scale, and the Low Self-Control Scale. A small to medium positive effect of self-control on behavior was found for the three scales. Only the Self-Control Scale allowed for a fine-grained analysis of conceptual moderators of the self-control behavior relation. Specifically, self-control (measured by the Self-Control Scale) related similarly to the performance of desired behaviors and the inhibition of undesired behaviors, but its effects varied dramatically across life domains (e.g., achievement, adjustment). In addition, the associations between self-control and behavior were significantly stronger for automatic (as compared to controlled) behavior and for imagined (as compared to actual) behavior.

/pdf/taking-stock-of-self-control-a-meta-analysis-of-how-trait-4o1a2xsgbu.pdf

Taking Stock of Self-Control A Meta-Analysis of How Trait Self-Control Relates to a Wide Range of Behaviors

Despite substantial fluctuations in daily food intake, animals maintain a remarkably stable body weight, because overall caloric ingestion and expenditure are exquisitely matched over long periods of time, through the process of energy homeostasis. The brain receives hormonal, neural, and metabolic signals pertaining to body-energy status and, in response to these inputs, coordinates adaptive alterations of energy intake and expenditure. To regulate food consumption, the brain must modulate appetite, and the core of appetite regulation lies in the gut-brain axis. This Review summarizes current knowledge regarding the neuroendocrine regulation of food intake by the gastrointestinal system, focusing on gastric distention, intestinal and pancreatic satiation peptides, and the orexigenic gastric hormone ghrelin. We highlight mechanisms governing nutrient sensing and peptide secretion by enteroendocrine cells, including novel taste-like pathways. The increasingly nuanced understanding of the mechanisms mediating gut-peptide regulation and action provides promising targets for new strategies to combat obesity and diabetes.

/pdf/gastrointestinal-regulation-of-food-intake-jydwlyfm04.pdf

James E. Cox

Papers

Widespread reward-system activation in obese women in response to pictures of high-calorie foods.

Obese women show greater delay discounting than healthy-weight women.

fMRI reactivity to high-calorie food pictures predicts short- and long-term outcome in a weight-loss program.

fMRI reactivity on a delay discounting task predicts weight gain in obese women

Effective connectivity of a reward network in obese women.