Session: MON 649-675-Central Regulation of Appetite & Feeding/GI Regulatory Peptides
Bench to Bedside
Poster Board MON-660
Background: Food intake and volitional energy expenditure are determined by brain processes, conscious and unconscious, that influence behavior. Increased food availability, habits and social cues, increased palatability, and genetic predisposition are factors that can influence these processes, leading to hedonic eating, over-consumption, and obesity. American Indians suffer disproportionately from obesity. With environmental, lifestyle, and genetic influences in the background, emotional, and metabolic signals converge on the brain to influence decisions about food intake. Perception of heightened food reward can lead to a net increase in food intake relative to energy expenditure, thus leading to obesity. Opioid neurons appear to influence pleasure eating, and recent studies highlight the role of opioids in reward processing and in experiencing pleasure. Brain opioidergic tone governs meal maintenance, ingestion of rewarding or preferred foods, and homeostatic food ingestion. Endogenous opioid systems modulate the hedonic value of food independent from metabolic, homeostatic energy needs. Neuronal processes that underlie obesity in American Indians are not well defined.
Objective: The objective of this study was to evaluate the effect of naltrexone, an opioid antagonist, on food intake at a buffet and on neural responses to visual food cues. This study is part of a large brain imaging study using functional magnetic resonance imaging (fMRI).
Methods: Caloric intake was assessed in 10 obese and non-obese American Indian women after a 12 hour fast and after taking placebo or naltrexone in a randomized double-blinded placebo-controlled crossover design. Caloric intake was assessed at a buffet where each woman ate alone without social influence. Study buffets were identical on both days. These fasted participants also underwent 2 fMRI scans while viewing images of high-calorie and low-calorie food, using a block design.
Results: Naltrexone significantly reduced food intake (P <0.05) as compared to placebo. fMRI data analyses are ongoing.
Conclusions: This study is the first to evaluate the effect of naltrexone on food intake and brain activation in obese and non-obese American Indian women. Opioidergic neurons appear to modulate food intake in this population. Our initial results in this area suggest that further work is warranted. This longitudinal study is ongoing.
Nothing to Disclose: TRB, PCB, KOL, CJB, EAS, DSB
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