PYY modulation of cortical and hypothalamic brain areas predicts feeding behaviour in humans
ABSTRACT The ability to maintain adequate nutrient intake is critical for survival. Complex interrelated neuronal circuits have developed in the mammalian brain to regulate many aspects of feeding behaviour, from food-seeking to meal termination. The hypothalamus and brainstem are thought to be the principal homeostatic brain areas responsible for regulating body weight1, 2. However, in the current ‘obesogenic’ human environment food intake is largely determined by non-homeostatic factors including cognition, emotion and reward, which are primarily processed in corticolimbic and higher cortical brain regions3. Although the pleasure of eating is modulated by satiety and food deprivation increases the reward value of food, there is currently no adequate neurobiological account of this interaction between homeostatic and higher centres in the regulation of food intake in humans1, 4, 5. Here we show, using functional magnetic resonance imaging, that peptide YY3–36 (PYY), a physiological gut-derived satiety signal, modulates neural activity within both corticolimbic and higher-cortical areas as well as homeostatic brain regions. Under conditions of high plasma PYY concentrations, mimicking the fed state, changes in neural activity within the caudolateral orbital frontal cortex predict feeding behaviour independently of meal-related sensory experiences. In contrast, in conditions of low levels of PYY, hypothalamic activation predicts food intake. Thus, the presence of a postprandial satiety factor switches food intake regulation from a homeostatic to a hedonic, corticolimbic area. Our studies give insights into the neural networks in humans that respond to a specific satiety signal to regulate food intake. An increased understanding of how such homeostatic and higher brain functions are integrated may pave the way for the development of new treatment strategies for obesity.
- SourceAvailable from: Hans Eickhoff02/2015, Degree: PhD, Supervisor: Francisco Castro e Sousa
Article: PYY3–36: Beyond food intake[Show abstract] [Hide abstract]
ABSTRACT: The gastrointestinal hormone peptide tyrosine tyrosine 3-36 (PYY3-36) has attained broad recognition with respect to its involvement in energy homeostasis and the control of food intake. It is mainly secreted by distal intestinal enteroendocrine L-cells in response to eating and exerts both neurally mediated paracrine and endocrine effects on various target organs. In addition to its gastrointestinal effects, PYY3-36 has long been known to inhibit food intake. Recent closer examination of the effects of PYY3-36 revealed that this gut-derived peptide also influences a wide spectrum of behavioral and cognitive functions that are pivotal for basic processes of perception and judgment, including central information processing, salience learning, working memory, and behavioral responding to novelty. Here, we review the effects of PYY3-36 that go beyond food intake and provide a conceptual framework suggesting that several apparently unrelated behavioral actions of PYY3-36 may actually reflect different manifestations of modulating the central dopamine system. Copyright © 2014. Published by Elsevier Inc.Frontiers in Neuroendocrinology 12/2014; DOI:10.1016/j.yfrne.2014.12.003 · 7.58 Impact Factor
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ABSTRACT: The gastrointestinal hormone PYY3-36 is a preferential Y2 neuropeptide Y (NPY) receptor agonist. Recent evidence indicates that PYY3-36 acts on central dopaminergic pathways, but its influence on dopamine-dependent behaviours remains largely unknown. We therefore explored the effects of peripheral PYY3-36 treatment on the behavioural responses to novelty and to dopamine-activating drugs in mice. In addition, we examined whether PYY3-36 administration may activate distinct dopamine and γ-aminobutyric acid (GABA) cell populations in the mesoaccumbal and nigrostriatal pathways. We found that i.p. PYY3-36 injection led to a dose-dependent increase in novel object exploration. The effective dose of PYY3-36 (1 μg/100 g body weight) also potentiated the locomotor reaction to the indirect dopamine receptor agonist amphetamine and increased stereotyped climbing/leaning responses following administration of the direct dopamine receptor agonist apomorphine. PYY3-36 administration did not affect activity of midbrain dopaminergic cells as evaluated by double immuno-enzyme staining of the neuronal early gene product c-Fos with tyrosine hydroxylase. PYY3-36 did, however, lead to a marked increase in the number of cells co-expressing c-Fos with glutamic acid decarboxylase in the nucleus accumbens and caudate putamen, indicating activation of GABAergic cells in dorsal and ventral striatal areas. Our results support the hypothesis that acute administration of the preferential Y2 receptor agonist PYY3-36 modulates dopamine-dependent behaviours. These effects do not seem to involve direct activation of midbrain dopamine cells but instead are associated with neuronal activation in the major input areas of the mesoaccumbal and nigrostriatal pathways.The International Journal of Neuropsychopharmacology 10/2013; 17(03):1-13. DOI:10.1017/S1461145713001223 · 5.26 Impact Factor