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Experimental & Molecular Medicine Apr 2022As the principal means of acquiring nutrients, feeding behavior is indispensable to the survival and well-being of animals. In response to energy or nutrient deficits,... (Review)
Review
As the principal means of acquiring nutrients, feeding behavior is indispensable to the survival and well-being of animals. In response to energy or nutrient deficits, animals seek and consume food to maintain energy homeostasis. On the other hand, even when animals are calorically replete, non-homeostatic factors, such as the sight, smell, and taste of palatable food, or environmental cues that predict food, can stimulate feeding behavior. These homeostatic and non-homeostatic factors have traditionally been investigated separately, but a growing body of literature highlights that these factors work synergistically to promote feeding behavior. Furthermore, recent breakthroughs in cell type-specific and circuit-specific labeling, recording, and manipulation techniques have markedly accelerated the discovery of well-defined neural populations underlying homeostatic and non-homeostatic appetite control, as well as overlapping circuits that contribute to both types of appetite. This review aims to provide an update on our understanding of the neural circuit mechanisms for promoting homeostatic and non-homeostatic appetites, focusing on the function of recently identified, genetically defined cell types.
Topics: Animals; Appetite; Brain; Feeding Behavior; Homeostasis
PubMed: 35474340
DOI: 10.1038/s12276-022-00758-4 -
Obesity Reviews : An Official Journal... Feb 2023Determining if gastrointestinal (GI) hormone response to food intake differs between individuals with, and without, obesity may improve our understanding of obesity... (Meta-Analysis)
Meta-Analysis Review
Determining if gastrointestinal (GI) hormone response to food intake differs between individuals with, and without, obesity may improve our understanding of obesity pathophysiology. A systematic review and meta-analysis of studies assessing the concentrations of GI hormones, as well as appetite ratings, following a test meal, in individuals with and without obesity was undertaken. Systematic searches were conducted in the databases MEDLINE, Embase, Cochrane Library, PsycINFO, Web of Science, and ClinicalTrials.gov. A total of 7514 unique articles were retrieved, 115 included in the systematic review, and 70 in the meta-analysis. The meta-analysis compared estimated standardized mean difference in GI hormones' concentration, as well as appetite ratings, between individuals with and without obesity. Basal and postprandial total ghrelin concentrations were lower in individuals with obesity compared with controls, and this was reflected by lower postprandial hunger ratings in the former. Individuals with obesity had a lower postprandial concentration of total peptide YY compared with controls, but no significant differences were found for glucagon-like peptide 1, cholecystokinin, or other appetite ratings. A large methodological and statistical heterogeneity among studies was found. More comprehensive studies are needed to understand if the differences observed are a cause or a consequence of obesity.
Topics: Humans; Appetite; Gastrointestinal Hormones; Obesity; Ghrelin; Peptide YY; Cholecystokinin; Postprandial Period
PubMed: 36416279
DOI: 10.1111/obr.13531 -
Critical Reviews in Food Science and... Nov 2017Ratings of appetite are commonly used to assess appetite modification following an intervention. Subjectively rated appetite is a widely employed proxy measure for... (Review)
Review
Ratings of appetite are commonly used to assess appetite modification following an intervention. Subjectively rated appetite is a widely employed proxy measure for energy intake (EI), measurement of which requires greater time and resources. However, the validity of appetite as a reliable predictor of EI has not yet been reviewed systematically. This literature search identified studies that quantified both appetite ratings and EI. Outcomes were predefined as: (1) agreement between self-reported appetite scores and EI; (2) no agreement between self-reported appetitescores and EI. The presence of direct statistical comparison between the endpoints, intervention type and study population were also recorded. 462 papers were included in this review. Appetite scores failed to correspond with EI in 51.3% of the total studies. Only 6% of all studies evaluated here reported a direct statistical comparison between appetite scores and EI. χ analysis demonstrated that any relationship between EI and appetite was independent of study type stratification by age, gender or sample size. The very substantive corpus reviewed allows us to conclude that self-reported appetite ratings of appetite do not reliably predict EI. Caution should be exercised when drawing conclusions based from self-reported appetite scores in relation to prospective EI.
Topics: Appetite; Energy Intake; Exercise; Humans; Prospective Studies
PubMed: 27736161
DOI: 10.1080/10408398.2016.1246414 -
PloS One 2018Observed associations between consumption of diet foods and obesity have sparked controversy over whether intense sweeteners may promote weight gain, despite their... (Meta-Analysis)
Meta-Analysis Review
Observed associations between consumption of diet foods and obesity have sparked controversy over whether intense sweeteners may promote weight gain, despite their negligible energy contribution. We conducted a scoping review of reviews, to obtain an overview of hypotheses, research approaches and features of the evidence on intense sweeteners' potential relationships to appetite and weight changes. We searched for reviews of the scientific literature published from 2006 to May 2017. Two reviewers independently assessed title and abstracts, and full text publications. Arksey and O'Malley's framework for scoping reviews guided the process. We extracted and charted data on characteristics of the reviews and the evidence presented. The 40 included reviews present hypotheses both on how intense sweeteners can reduce or maintain body weight and on how these can promote weight gain. We classified only five publications as systematic reviews; another nine presented some systematic approaches, while 26 reviews did not describe criteria for selecting or assessing the primary studies. Evidence was often presented for intense sweeteners as a group or unspecified, and against several comparators (e.g. sugar, water, placebo, intake levels) with limited discussion on the interpretation of different combinations. Apart from the observational studies, the presented primary evidence in humans is dominated by small studies with short follow-up-considered insufficient to assess weight change. Systematic reviews of animal studies are lacking in this topic area. The systematic evidence only partly explore forwarded hypotheses found in the literature. Primary studies in humans seem to be available for systematic exploration of some hypotheses, but long-term experimental studies in humans appear sparse. With few exceptions, the reviews on intense sweeteners and weight change underuse systematic methodology, and thus, the available evidence. Further studies and systematic reviews should be explicit about the hypothesis explored and elucidate possible underlying mechanisms.
Topics: Appetite; Body Weight; Humans; Public Health Surveillance; Sweetening Agents
PubMed: 30020966
DOI: 10.1371/journal.pone.0199558 -
Comprehensive Physiology Sep 2016Perhaps the most salient behaviors that individuals engage in involve the avoidance of aversive experiences and the pursuit of pleasurable experiences. Engagement in... (Review)
Review
Perhaps the most salient behaviors that individuals engage in involve the avoidance of aversive experiences and the pursuit of pleasurable experiences. Engagement in these behaviors is regulated to a significant extent by an individual's hormonal milieu. For example, glucocorticoid hormones are produced by the hypothalamic-pituitary-adrenocortical (HPA) axis, and influence most aspects of behavior. In turn, many behaviors can influence HPA axis activity. These bidirectional interactions not only coordinate an individual's physiological and behavioral states to each other, but can also tune them to environmental conditions thereby optimizing survival. The present review details the influence of the HPA axis on many types of behavior, including appetitively-motivated behaviors (e.g., food intake and drug use), aversively-motivated behaviors (e.g., anxiety-related and depressive-like) and cognitive behaviors (e.g., learning and memory). Conversely, the manuscript also describes how engaging in various behaviors influences HPA axis activity. Our current understanding of the neuronal and/or hormonal mechanisms that underlie these interactions is also summarized. © 2016 American Physiological Society. Compr Physiol 6:1897-1934, 2016.
Topics: Animals; Appetite; Behavior; Humans; Hypothalamo-Hypophyseal System; Learning; Pituitary-Adrenal System; Stress, Psychological
PubMed: 27783863
DOI: 10.1002/cphy.c150042 -
Annals of Nutrition & Metabolism 2018Identifying the underlying child-eating behaviours that contribute to weight differences across growth has been a constant challenge. This report reviews the various... (Review)
Review
Identifying the underlying child-eating behaviours that contribute to weight differences across growth has been a constant challenge. This report reviews the various literature approaches for assessing appetite regulation. In doing so, it attempts to understand how appetite control develops and determines the eating habits in early childhood, and its effects on children's weight status. The interaction between homeostatic and hedonic mechanisms largely explains the appetite regulation process. Homeostatic mechanisms are mediated by the biological need to maintain the body's energy reserves, increasing the motivation to eat. On the contrary, the hedonic mechanisms are mediated by food reward, increasing the craving for high-palatable foods and triggering the release of dopamine and serotonin. There are many biological methods (plasma measurements of hormones, like leptin, ghrelin and insulin) and behavioural evaluation methods of appetite. The Children's Eating Behaviour Questionnaire is most commonly used, due to its adequate psychometric properties tested in several population settings. The development of eating behaviours begins in utero, and several determinants may contribute to a decrease in the ability to self-regulate dietary intake. Examples include genetic predisposition, the first taste experiences and the family environment, a key determinant in this process. Several eating behaviours contribute most to childhood obesity. Among them, are the external eating (eating by external stimuli, such as the mere presence of the food or its smell), food restriction (which may potentiate the uninhibited increased intake of the restricted foods) and emotional eating (intake due to emotional variations, especially negative feelings). These eating behaviours have been linked to childhood obesity.
Topics: Appetite; Appetite Regulation; Body Weight; Child; Child Behavior; Child, Preschool; Feeding Behavior; Homeostasis; Humans; Infant; Pediatric Obesity
PubMed: 29843129
DOI: 10.1159/000489824 -
Annals of the New York Academy of... Jan 2018The central nervous system (CNS) plays a vital role in regulating energy balance and metabolism. Over the last 50 years, studies in animal models have allowed us to... (Review)
Review
The central nervous system (CNS) plays a vital role in regulating energy balance and metabolism. Over the last 50 years, studies in animal models have allowed us to identify critical CNS regions involved in these processes and even crucial cell populations. Now, techniques for genetically and anatomically targeted manipulation of specific neural populations using light (optogenetic), ligands (chemogenetic), or magnetic fields (radiogenetic/magnetogenetic) allow detailed investigation of circuits involved in metabolic regulation. In this review, we provide a brief overview of recent studies using light- and magnetic field-regulated neural activity to investigate the neural circuits contributing to metabolic control.
Topics: Animals; Appetite; Central Nervous System; Electromagnetic Fields; Energy Metabolism; Equipment Design; Feeding Behavior; Gene Expression Regulation; Glucose; Homeostasis; Humans; Hypothalamus; Ion Channels; Lasers; Magnetite Nanoparticles; Neurons; Optogenetics; Protein Engineering; Receptors, G-Protein-Coupled
PubMed: 29106710
DOI: 10.1111/nyas.13468 -
Behavioral and Brain Functions : BBF May 2016We enjoy a sophisticated understanding of how animals learn to predict appetitive outcomes and direct their behaviour accordingly. This encompasses well-defined learning... (Review)
Review
We enjoy a sophisticated understanding of how animals learn to predict appetitive outcomes and direct their behaviour accordingly. This encompasses well-defined learning algorithms and details of how these might be implemented in the brain. Dopamine has played an important part in this unfolding story, appearing to embody a learning signal for predicting rewards and stamping in useful actions, while also being a modulator of behavioural vigour. By contrast, although choosing correct actions and executing them vigorously in the face of adversity is at least as important, our understanding of learning and behaviour in aversive settings is less well developed. We examine aversive processing through the medium of the role of dopamine and targets such as D2 receptors in the striatum. We consider critical factors such as the degree of control that an animal believes it exerts over key aspects of its environment, the distinction between 'better' and 'good' actual or predicted future states, and the potential requirement for a particular form of opponent to dopamine to ensure proper calibration of state values.
Topics: Adaptation, Psychological; Animals; Appetite; Avoidance Learning; Behavior, Animal; Brain; Corpus Striatum; Decision Making; Dopamine; Neurons; Receptors, Dopamine D2
PubMed: 27216176
DOI: 10.1186/s12993-016-0099-7 -
Philosophical Transactions of the Royal... Jul 2006Interest in the biology of white adipose tissue has risen markedly with the recent surge in obesity and its associated disorders. The tissue is no longer viewed simply... (Review)
Review
Interest in the biology of white adipose tissue has risen markedly with the recent surge in obesity and its associated disorders. The tissue is no longer viewed simply as a vehicle for lipid storage; instead, it is recognized as a major endocrine and secretory organ. White adipocytes release a multiplicity of protein hormones, signals and factors, termed adipokines, with an extensive range of physiological actions. Foremost among these various adipokines is the cytokine-like hormone, leptin, which is synthesized predominantly in white fat. Leptin plays a critical role in the control of appetite and energy balance, with mutations in the genes encoding the hormone or its receptor leading to profound obesity in both rodents and man. Leptin regulates appetite primarily through an interaction with hypothalamic neuroendocrine pathways, inhibiting orexigenic peptides such as neuropeptide Y and orexin A, and stimulating anorexigenic peptides such as proopiomelanocortin. White fat also secretes several putative appetite-related adipokines, which include interleukin-6 and adiponectin, but whether these are indeed significant signals in the regulation of food intake has not been established. Through leptin and the other adipokines it is evident that adipose tissue communicates extensively with other organs and plays a pervasive role in metabolic homeostasis.
Topics: Adipocytes; Adipose Tissue; Appetite; Energy Metabolism; Humans
PubMed: 16815801
DOI: 10.1098/rstb.2006.1859 -
Expert Review of Clinical Pharmacology Mar 2011Obesity has escalated into a pandemic over the past few decades. In turn, research efforts have sought to elucidate the molecular mechanisms underlying the regulation of... (Review)
Review
Obesity has escalated into a pandemic over the past few decades. In turn, research efforts have sought to elucidate the molecular mechanisms underlying the regulation of energy balance. A host of endogenous mediators regulate appetite and metabolism, and thereby control both short- and long-term energy balance. These mediators, which include gut, pancreatic and adipose neuropeptides, have been targeted in the development of anti-obesity pharmacotherapy, with the goal of amplifying anorexigenic and lipolytic signaling or blocking orexigenic and lipogenic signaling. This article presents the efficacy and safety of these anti-obesity drugs.
Topics: Animals; Anti-Obesity Agents; Appetite; Appetite Regulation; Eating; Humans; Obesity; Treatment Outcome
PubMed: 21666781
DOI: 10.1586/ecp.11.3