SNP analyses of postprandial responses in (an)orexigenic hormones and feelings of hunger reveal long-term physiological adaptations to facilitate homeostasis.

BACKGROUND: The postprandial responses in (an)orexigenic hormones and feelings of hunger are characterized by large inter-individual differences. Food intake regulation was shown earlier to be partly under genetic control. OBJECTIVE: This study aimed to determine whether the postprandial responses in (an)orexigenic hormones and parameters of food intake regulation are associated with single nucleotide polymorphisms (SNPs) in genes encoding for satiety hormones and their receptors. DESIGN: Peptide YY (PYY), glucagon-like peptide 1 and ghrelin levels, as well as feelings of hunger and satiety, were determined pre- and postprandially in 62 women and 41 men (age 31+/-14 years; body mass index 25.0+/-3.1 kg/m(2)). Dietary restraint, disinhibition and perceived hunger were determined using the three-factor eating questionnaire. SNPs were determined in the GHRL, GHSR, LEP, LEPR, PYY, NPY, NPY2R and CART genes. RESULTS: The postprandial response in plasma ghrelin levels was associated with SNPs in PYY (215G>C, P<0.01) and LEPR (326A>G and 688A>G, P<0.01), and in plasma PYY levels with SNPs in GHRL (-501A>C, P<0.05) and GHSR (477G>A, P<0.05). The postprandial response in feelings of hunger was characterized by an SNP-SNP interaction involving SNPs in LEPR and NPY2R (668A>G and 585T>C, P<0.05). Dietary restraint and disinhibition were associated with an SNP in GHSR (477G>A, P<0.05), and perceived hunger with SNPs in GHSR and NPY (477G>A and 204T>C, P<0.05). CONCLUSIONS: Part of the inter-individual variability in postprandial responses in (an)orexigenic hormones can be explained by genetic variation. These postprandial responses represent either long-term physiological adaptations to facilitate homeostasis or reinforce direct genetic effects.

Oral exposure and sensory-specific satiety.

Satiety has been shown after oral exposure to food that was chewed but not eaten (Modified Sham Feeding (MSF)). The aim of the study was to explore the role of sensory-specific satiety (SSS) in satiety development with MSF. Subjects were studied on three test days in a randomized crossover design; they received, in random order, water, MSF, or a meal. At the start and the end of each course of the lunch condition subjects evaluated appetite sensations, taste perception and pleasantness of taste using Visual Analogue Scales. SSS was present when eating soup and salad. SSS also occurred with MSF of salad. When eating the soup no significant changes in appetite ratings occurred. Hunger decreased and satiety increased while the salad was eaten (p<0.0004). In this condition taste perception did not change significantly and a decrease in pleasantness coincided with an increase in satiety. During the MSF salad taste perception changed, i.e. creaminess and intensity increased (p<0.05 and p<0.02, respectively). When the salad was eaten satiety increased and hunger and desire to eat (DTE) decreased. Chewing the salad resulted only in a decrease in DTE. In this experiment merely chewing a salad produced SSS. We conclude that when SSS takes place during feeding, it is related to an increase in satiety, and a decrease in hunger and DTE. With SSS during MSF, satiety does not increase, nor does hunger decrease, yet DTE decreases. Thus MSF is sufficient for a sensory decrease in DTE despite of lack of satiety.