Obesity is a major worldwide health problem with limited treatment options. Recent research has highlighted the importance of gastrointestinal (GI) nutrient sensing in the regulation of food intake and metabolism. Protein as a macronutrient induces the strongest feeling of satiety per calorie. However, different types of protein have varying effects on appetite, suggesting protein induced satiety may be due to the specific amino acids generated by protein digestion. We have identified individual amino acids that influence food intake in rodents when administered orally or intraperitoneally. However, a reduction in food intake does not necessarily reflect activation of a satiety pathway. To determine whether these amino acids have specific effects on appetite we have utilized additional protocols to assess the mechanisms through which this reduction occurs. To investigate whether the reduction in food intake was induced by feelings of visceral illness, a conditioned taste aversion protocol was employed. To investigate whether the anorectic effects were mediated via neural pathways in the brainstem and hypothalamus, Cfos-like immunoreactivity (cFLI) in these areas was examined following oral administration. To further investigate the mechanism by which these amino acids exert their effect, food intake was measured following administration directly in to the third ventricle of overnight fasted rats. Our results suggest that amino acids can specifically influence food intake in rodents.
Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
Funding: Declaration of Funding: The Section is funded by grants from the MRC, BBSRC, NIHR, an Integrative Mammalian Biology (IMB) Capacity Building Award, an FP7- HEALTH- 2009- 241592 EuroCHIP grant and is supported by the NIHR Imperial Biomedical Research Centre Funding Scheme.