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McGrath TM, Spreckley E, Rodriguez AF, Viscomi C, Alamshah A, Akalestou E, Murphy KG, Jones NS. The homeostatic dynamics of feeding behaviour identify novel mechanisms of anorectic agents. PLoS Biol 2019; 17:e3000482. [PMID: 31805040 PMCID: PMC6894749 DOI: 10.1371/journal.pbio.3000482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Accepted: 11/01/2019] [Indexed: 12/26/2022] Open
Abstract
Better understanding of feeding behaviour will be vital in reducing obesity and metabolic syndrome, but we lack a standard model that captures the complexity of feeding behaviour. We construct an accurate stochastic model of rodent feeding at the bout level in order to perform quantitative behavioural analysis. Analysing the different effects on feeding behaviour of peptide YY3-36 (PYY3-36), lithium chloride, glucagon-like peptide 1 (GLP-1), and leptin shows the precise behavioural changes caused by each anorectic agent. Our analysis demonstrates that the changes in feeding behaviour evoked by the anorectic agents investigated do not mimic the behaviour of well-fed animals and that the intermeal interval is influenced by fullness. We show how robust homeostatic control of feeding thwarts attempts to reduce food intake and how this might be overcome. In silico experiments suggest that introducing a minimum intermeal interval or modulating upper gut emptying can be as effective as anorectic drug administration.
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Affiliation(s)
- Thomas M. McGrath
- Department of Mathematics, Imperial College London, London, United Kingdom
- EPSRC Centre for the Mathematics of Precision Healthcare, Imperial College London, London, United Kingdom
| | - Eleanor Spreckley
- Section of Endocrinology and Investigative Medicine, Imperial College London, London, United Kingdom
| | - Aina Fernandez Rodriguez
- Section of Endocrinology and Investigative Medicine, Imperial College London, London, United Kingdom
| | - Carlo Viscomi
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Amin Alamshah
- Section of Endocrinology and Investigative Medicine, Imperial College London, London, United Kingdom
| | - Elina Akalestou
- Section of Endocrinology and Investigative Medicine, Imperial College London, London, United Kingdom
| | - Kevin G. Murphy
- Section of Endocrinology and Investigative Medicine, Imperial College London, London, United Kingdom
| | - Nick S. Jones
- Department of Mathematics, Imperial College London, London, United Kingdom
- EPSRC Centre for the Mathematics of Precision Healthcare, Imperial College London, London, United Kingdom
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Figueiredo-Silva AC, Saravanan S, Schrama JW, Kaushik S, Geurden I. Macronutrient-induced differences in food intake relate with hepatic oxidative metabolism and hypothalamic regulatory neuropeptides in rainbow trout (Oncorhynchus mykiss). Physiol Behav 2012; 106:499-505. [PMID: 22484564 DOI: 10.1016/j.physbeh.2012.03.027] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 03/08/2012] [Accepted: 03/22/2012] [Indexed: 10/28/2022]
Abstract
This study examines how dietary macronutrient-induced changes in voluntary food intake (FI) relate to changes in markers of hepatic oxidative metabolism and in the expression of FI regulatory neuropeptides in a teleost model, the rainbow trout. Rainbow trout were fed for 6weeks with one of four iso-energetic diets (2×2 factorial design), containing either a high (HP, ~500 g·kg(-1) DM) or a low (LP, ~250 g·kg(-1) DM) protein level (PL) with, at each PL, fat (diets HP-F and LP-F) being substituted by an iso-energetic amount of gelatinized corn starch (diets HP-St and LP-St) as non-protein energy source (ES). Irrespective of the dietary PL, FI (g·kg(-0.8)·d(-1)) and digestible energy intake (DEI, kJ·kg(-0.8)·d(-1)) were significantly (P<0.05) reduced by the iso-energetic replacement of fat by starch as non-protein ES. Interestingly, trout fed these St-diets had higher gene expression of markers of hepatic oxidative phosphorylation (OxPhos), i.e., ubiquinol-cytochrome c reductase subunit 2 (UCR2) and cytochrome oxidase subunit 4 (COX4) and of aerobic oxidative capacity (CS, citrate synthase), which paralleled glucokinase (GK) transcription. This positive relation suggests that glucose phosphorylation and markers of mitochondrial OxPhos are linked at the hepatic level and possibly triggered the observed reduction in FI. Moreover, trout displaying the reduced FI had higher cocaine amphetamine regulator transcript (CART) mRNA in hypothalamus, whereas neuropeptide Y (NPY) mRNA did not follow the macronutrient-induced changes in FI. Further studies are needed to unravel the mechanisms by which diet-induced changes in hepatic metabolism inform central feeding centers involved in the regulation of FI in fish.
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Abstract
When administered into the brain, NPY acts at Y1 and Y5 receptors to increase food intake. The response occurs with a short latency and is quite robust, such that exogenous NPY is generally considered to be the most potent of a growing list of orexigenic compounds that act in the brain. The role of endogenous NPY is not so straightforward, however. Evidence from diverse types of experiments suggests that rather than initiating behavioral eating per se, endogenous NPY elicits autonomic responses that prepare the individual to better cope with consuming a calorically large meal.
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Affiliation(s)
- Adam P Chambers
- Departments of Medicine, University of Cincinnati, OH 45237, USA
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4
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Petrovich GD. Learning and the motivation to eat: forebrain circuitry. Physiol Behav 2011; 104:582-9. [PMID: 21549730 PMCID: PMC3446257 DOI: 10.1016/j.physbeh.2011.04.059] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2011] [Revised: 04/15/2011] [Accepted: 04/28/2011] [Indexed: 11/27/2022]
Abstract
Appetite and eating are not only controlled by energy needs, but also by extrinsic factors that are not directly related to energy balance. Environmental signals that acquire motivational properties through associative learning-learned cues-can override homeostatic signals and stimulate eating in sated states, or inhibit eating in states of hunger. Such influences are important, as environmental factors are believed to contribute to the increased susceptibility to overeating and the rise in obesity in the developed world. Similarly, environmental and social factors contribute to the onset and maintenance of anorexia nervosa and other eating disorders through interactions with the individual genetic background. Nevertheless, how learning enables environmental signals to control feeding, and the underlying brain mechanisms are poorly understood. We developed two rodent models to study how learned cues are integrated with homeostatic signals within functional forebrain networks, and how these networks are modulated by experience. In one model, a cue previously paired with food when an animal was hungry induces eating in sated rats. In the other model, food-deprived rats inhibit feeding when presented with a cue that signals danger, a tone previously paired with footshocks. Here evidence will be reviewed that the forebrain network formed by the amygdala, lateral hypothalamus and medial prefrontal cortex mediates cue-driven feeding, while a parallel amygdalar circuitry mediates suppression of eating by the fear cue. Findings from the animal models may be relevant for understanding aspects of human appetite and eating, and maladaptive mechanisms that could lead to overeating and anorexia.
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Affiliation(s)
- Gorica D Petrovich
- Department of Psychology, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA.
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5
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Abstract
To investigate the early scientific development of Steve Woods, I reviewed his research during the first decade after he received his doctoral degree in 1970. The main parts of his research program were conditioned insulin secretion and hypoglycemia, Pavlovian conditioning of insulin secretion before a scheduled access to food, and basal insulin as a negative-feedback signal from fat mass to the brain. These topics were pursued with experimental ingenuity; the resulting publications were interesting, clear, and rhetorically effective. Although the theoretical framework for his experiments with insulin was homeostatic, by the end of the decade he suggested that classic negative-feedback homeostasis needed to be revised to include learning acquired by lifestyle. Thus, Woods functioned as a mature scientist from the beginning of his research-he was very precocious. This precocity also characterized his teaching and mentoring as recalled by two of his students during that time, Joseph Vasselli and Paul Kulkosky. The most unusual and exemplary aspect of his precocity is that the outstanding performance of his first decade was maintained during the subsequent 30years.
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Affiliation(s)
- Gerard P Smith
- Department of Psychiatry, Weill Cornell Medical College of Cornell University, Payne Whitney Westchester, New York-Presbyterian Hospital, 21 Bloomingdale Road,White Plains, NY 10605, United States.
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Newquist G. Brain organization and the roots of anticipation in Drosophila olfactory conditioning. Neurosci Biobehav Rev 2010; 35:1166-74. [PMID: 21168436 DOI: 10.1016/j.neubiorev.2010.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 12/09/2010] [Accepted: 12/10/2010] [Indexed: 11/16/2022]
Abstract
Defining learning at the molecular and physiological level has been one of the greatest challenges in biology. Recent research suggests that by studying fruit fly (Drosophila melanogaster) brain organization we can now begin to unravel some of these mysteries. The fruit fly brain is organized into executive centers that regulate anatomically separate behavioral systems. The mushroom body is an example of an executive center which is modified by olfactory conditioning. During this simple form of learning, an odor is paired with either food or shock. Either experience alters distinguishable specific circuitry within the mushroom body. Results suggest that after conditioning an odor to food, the mushroom body will activate a feeding system via a subset of its circuitry. After conditioning an odor to shock, the mushroom body will instead activate an avoidance system with other subsets of mushroom body neurons. The results of these experiments demonstrate a mechanism for flies to display anticipation of their environment after olfactory conditioning has occurred. However, these results fail to provide evidence for reinforcement, a consequence of action, as part of this mechanism. Instead, specific subsets of dopaminergic and octopaminergic neurons provide a simple pairing signal, in contrast to a reinforcement signal, which allows for prediction of the environment after experience. This view has implications for models of conditioning.
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Affiliation(s)
- Gunnar Newquist
- Cell and Molecular Biology Program, Department of Biology, University of Nevada, Reno, NV 89557, United States.
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Petrovich GD. Forebrain circuits and control of feeding by learned cues. Neurobiol Learn Mem 2010; 95:152-8. [PMID: 20965265 DOI: 10.1016/j.nlm.2010.10.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 09/30/2010] [Accepted: 10/07/2010] [Indexed: 11/16/2022]
Abstract
Professor Richard F. Thompson and his highly influential work on the brain substrates of associative learning and memory have critically shaped my research interests and scientific approach. I am tremendously grateful and thank Professor Thompson for the support and influence on my research and career. The focus of my research program is on associative learning and its role in the control of fundamental, motivated behaviors. My long-term research goal is to understand how learning enables environmental cues to control feeding behavior. We use a combination of behavioral studies and neural systems analysis approach in two well-defined rodent models to study how learned cues are integrated with homeostatic signals within functional forebrain networks, and how these networks are modulated by experience. Here, I will provide an overview of the two behavioral models and the critical neural network components mapped thus far, which include areas in the forebrain, the amygdala and prefrontal cortex, critical for associative learning and decision-making, and the lateral hypothalamus, which is an integrator for feeding, reward and motivation.
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Dopamine and binge eating behaviors. Pharmacol Biochem Behav 2010; 97:25-33. [PMID: 20417658 DOI: 10.1016/j.pbb.2010.04.016] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 03/23/2010] [Accepted: 04/19/2010] [Indexed: 01/15/2023]
Abstract
Central dopaminergic mechanisms are involved in the motivational aspects of eating and food choices. This review focuses on human and animal data investigating the importance of dopamine on binge eating behaviors. Early work examining dopamine metabolites in the cerebrospinal fluid and plasma of bulimic individuals suggested decreased dopamine turnover during the active phase of the illness. While neuroimaging studies of dopamine mechanisms in bulimia nervosa (BN) and binge eating disorder (BED) are limited, genetic studies in humans have implicated an increased frequency of dopamine transporter and associated D2 receptor polymorphisms with binge pathology. Recent studies in rodent models of dietary-induced binge eating (DIBE) have investigated plausible dopamine mechanisms involved in sustaining binge eating behaviors. In DIBE models, highly palatable foods (fats, sugars and their combination), as well as restricted access conditions appear to promote ingestive responses and result in sustained dopamine stimulation within the nucleus accumbens. Taken together with studies on the comorbidity of illicit drug use and eating disorders, the data reviewed here support a role for dopamine in perpetuating the compulsive feeding patterns of BN and BED. As such, we propose that sustained stimulation of the dopamine systems by bingeing promoted by preexisting conditions (e.g., genetic traits, dietary restraint, stress, etc.) results in progressive impairments of dopamine signaling. To disrupt this vicious cycle, novel research-based treatment options aiming at the neural substrates of compulsive eating patterns are necessary.
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Scheurink AJW, Boersma GJ, Nergårdh R, Södersten P. Neurobiology of hyperactivity and reward: agreeable restlessness in anorexia nervosa. Physiol Behav 2010; 100:490-5. [PMID: 20361989 DOI: 10.1016/j.physbeh.2010.03.016] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 03/18/2010] [Indexed: 11/18/2022]
Abstract
Restricted food intake is associated with increased physical activity, very likely an evolutionary advantage, initially both functional and rewarding. The hyperactivity of patients with anorexia nervosa, however, is a main problem for recovery. This seemingly paradoxical reward of hyperactivity in anorexia nervosa is one of the main aspects in our framework for the neurobiological changes that may underlie the development of the disorder. Here, we focus on the neurobiological basis of hyperactivity and reward in both animals and humans suggesting that the mesolimbic dopamine and hypothalamic orexin neurons play central roles. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009.
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The Brain-insulin Connection, Metabolic Diseases and Related Pathologies. DIABETES, INSULIN AND ALZHEIMER'S DISEASE 2010. [DOI: 10.1007/978-3-642-04300-0_2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Bello NT, Guarda AS, Terrillion CE, Redgrave GW, Coughlin JW, Moran TH. Repeated binge access to a palatable food alters feeding behavior, hormone profile, and hindbrain c-Fos responses to a test meal in adult male rats. Am J Physiol Regul Integr Comp Physiol 2009; 297:R622-31. [PMID: 19535681 DOI: 10.1152/ajpregu.00087.2009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Repetitive cycles of palatable food access and chronic calorie restriction alter feeding behaviors and forebrain neural systems. The purpose of this study was to determine the behavioral, endocrine, and meal-related hindbrain neural activation in adult male Sprague-Dawley rats exposed to a binge-access feeding schedule. The binge-access schedule consisted of repeated twice-per-week episodes of acute calorie restriction (to one-third of the previous day's intake) followed by 2 h of concurrent access to high-calorie palatable food (sweetened fat: 90% vegetable shortening-10% sucrose) and chow. The binge-access rats consumed more calories during the "binge" period than rats with continuous access to sweetened fat (continuous-access group) or subjected to repeated acute calorie restriction only (chow-restricted group). The binge-access group also exhibited a approximately 25% increase in sweetened fat intake from week 1 to week 6. Persistence of the binge phenotype in the binge-access animals was demonstrated 2 wk, but not 4 wk, after ad libitum chow. The binge-access and chow-restricted groups maintained a similar normal body composition and hormonal profiles, whereas the continuous-access animals developed an obese phenotype. Terminal ghrelin levels were significantly higher in the binge-access group than in the continuous-access group. Consumption of a standardized meal resulted in more c-Fos-positive cells along the anterior-posterior nucleus of the solitary tract regions in the binge-access group than in naive controls. These results suggest that repeated cycles of acute calorie restriction followed by palatable food produce physiological alterations that may facilitate overconsumption of a highly palatable food during limited-access periods.
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Affiliation(s)
- Nicholas T Bello
- Dept. of Psychiatry and Behavioral Sciences, Johns Hopkins Univ. School of Medicine, Ross 618, 720 Rutland Ave., Baltimore, MD 21205, USA.
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12
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Södersten P, Nergårdh R, Bergh C, Zandian M, Scheurink A. Behavioral neuroendocrinology and treatment of anorexia nervosa. Front Neuroendocrinol 2008; 29:445-62. [PMID: 18602416 DOI: 10.1016/j.yfrne.2008.06.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Revised: 05/29/2008] [Accepted: 06/06/2008] [Indexed: 12/20/2022]
Abstract
Outcome in anorexia nervosa remains poor and a new way of looking at this condition is therefore needed. To this aim, we review the effects of food restriction and starvation in humans. It is suggested that body weight remains stable and relatively low when the access to food requires a considerable amount of physical activity. In this condition, the human homeostatic phenotype, body fat content is also low and as a consequence, the synthesis and release of brain neurotransmitters are modified. As an example, the role of neuropeptide Y is analyzed in rat models of this state. It is suggested that the normal behavioral role of neuropeptide Y is to facilitate the search for food and switch attention from sexual stimuli to food. Descriptive neuroendocrine studies on patients with anorexia nervosa have not contributed to the management of the patients and the few studies in which hormones have been administered have, at best, reversed an endocrine consequence secondary to starvation. In a modified framework for understanding the etiology and treatment of anorexia nervosa it is suggested that the condition emerges because neural mechanisms of reward and attention are engaged. The neural neuropeptide Y receptor system may be involved in the maintenance of the behavior of eating disorder patients because the localization of these receptors overlaps with the neural systems engaged in cue-conditioned eating in limbic and cortical areas. The eating behavior of patients with anorexia nervosa, and other eating disorders as well, is viewed as a cause of the psychological changes of the patients. Patients are trained to re-learn normal eating habits using external support and as they do, their symptoms, including the psychological symptoms, dissolve.
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Affiliation(s)
- P Södersten
- Karolinska Institutet, Section of Applied Neuroendocrinology, Mandometer Clinic, AB Mando Novum, S-141 57 Huddinge, Sweden.
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Gerozissis K. Brain insulin, energy and glucose homeostasis; genes, environment and metabolic pathologies. Eur J Pharmacol 2008; 585:38-49. [PMID: 18407262 DOI: 10.1016/j.ejphar.2008.01.050] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Revised: 11/30/2007] [Accepted: 01/21/2008] [Indexed: 11/18/2022]
Abstract
The central nervous system is essential in maintaining energy and glucose homeostasis. In both animals and humans, efficient cerebral insulin signalling is a pivotal control element in these pathophysiological processes. The action of insulin in the brain is under a multilevel control via metabolic, endocrine and neural signals induced by nutrients, integrated mainly by the hypothalamus. Of particular interest is the interaction of insulin with the anabolic and catabolic neuroregulators. The anorexic peptides insulin, leptin and the neurotransmitter serotonin share common signalling pathways involved in food intake, in particular the insulin receptor substrate, phosphatidylinositol-3-kinase (PI3K) pathway. The dialogue of neurotransmitters and peptides via this signalling pathway is potentially of major importance in the pathophysiology of the brain in general and specifically in the regulation of feeding behaviour. At this time, a new concept in the aetiopathology of type 2 diabetes is immerging. This concept proposes that the combination of defective pancreatic beta-cell function and insulin resistance not only in classical insulin target tissues but in every tissue, contributes to the onset of the disease. It highlights the importance of the disruption of cerebral insulin signal transmission and its direct relation to metabolic diseases. Impaired brain insulin signalling, a link coupling obesity to diabetes, may be related to either genetic factors, or environmental factors such as stress, over or under-feeding and unbalanced diets: such factors may work either independently or in concert. Current approaches used for the prevention and treatment of type 2 diabetes are not adequately effective. Most of the anti-diabetic therapies induce many adverse effects, in particular obesity, and thus may initiate a vicious cycle of problems. In order to develop new, more efficient, preventive and therapeutic strategies for metabolic pathologies, there is an urgent need for increased understanding of the complexity of insulin signalling in the brain and on the interactive, central and peripheral effects of insulin.
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Affiliation(s)
- Kyriaki Gerozissis
- Chercheur INSERM, UMR 7059 CNRS, University Paris 7, 2 place Jussieu, case 7126, 75251 Paris CEDEX 05, France.
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Beck B. Neuropeptide Y in normal eating and in genetic and dietary-induced obesity. Philos Trans R Soc Lond B Biol Sci 2007; 361:1159-85. [PMID: 16874931 PMCID: PMC1642692 DOI: 10.1098/rstb.2006.1855] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Neuropeptide Y (NPY) is one the most potent orexigenic peptides found in the brain. It stimulates food intake with a preferential effect on carbohydrate intake. It decreases latency to eat, increases motivation to eat and delays satiety by augmenting meal size. The effects on feeding are mediated through at least two receptors, the Y1 and Y5 receptors. The NPY system for feeding regulation is mostly located in the hypothalamus. It is formed of the arcuate nucleus (ARC), where the peptide is synthesized, and the paraventricular (PVN), dorsomedial (DMN) and ventromedial (VMN) nuclei and perifornical area where it is active. This activity is modulated by the hindbrain and limbic structures. It is dependent on energy availability, e.g. upregulation with food deprivation or restriction, and return to baseline with refeeding. It is also sensitive to diet composition with variable effects of carbohydrates and fats. Leptin signalling and glucose sensing which are directly linked to diet type are the most important factors involved in its regulation. Absence of leptin signalling in obesity models due to gene mutation either at the receptor level, as in the Zucker rat, the Koletsky rat or the db/db mouse, or at the peptide level, as in ob/ob mouse, is associated with increased mRNA abundance, peptide content and/or release in the ARC or PVN. Other genetic obesity models, such as the Otsuka-Long-Evans-Tokushima Fatty rat, the agouti mouse or the tubby mouse, are characterized by a diminution in NPY expression in the ARC nucleus and by a significant increase in the DMN. Further studies are necessary to determine the exact role of NPY in these latter models. Long-term exposure to high-fat or high-energy palatable diets leads to the development of adiposity and is associated with a decrease in hypothalamic NPY content or expression, consistent with the existence of a counter-regulatory mechanism to diminish energy intake and limit obesity development. On the other hand, an overactive NPY system (increased mRNA expression in the ARC associated with an upregulation of the receptors) is characteristic of rats or rodent strains sensitive to dietary-induced obesity. Finally, NPY appears to play an important role in body weight and feeding regulation, and while it does not constitute the only target for drug treatment of obesity, it may nevertheless provide a useful target in conjunction with others.
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Affiliation(s)
- B Beck
- Université Henri Poincaré, Neurocal, Nancy, France.
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15
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Levin BE. Central regulation of energy homeostasis intelligent design: how to build the perfect survivor. Obesity (Silver Spring) 2006; 14 Suppl 5:192S-196S. [PMID: 17021365 DOI: 10.1038/oby.2006.307] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The perfect survivor must be able to eat and store as many calories as possible when food is readily available as a buffer against periods of scarcity. He must also reduce energy expenditure when food is scarce and efficiently and accurately restore lost adipose stores when food is again available. These processes are dependent on information relayed to a distributed central network of metabolic sensing neurons through hard-wired neural, metabolic, and hormonal signals from the periphery. These sensing neurons engage neuroendocrine, autonomic, and motor processes involved in arousal, motor activity, and the ingestion, absorption, assimilation, storage, and expenditure of calories. A raised threshold in these metabolic sensors for detecting inhibitory signals from increasing adipose stores allows continued intake of excess calories when they are readily available. Unfortunately, this mechanism for surviving periods of feast and famine predisposes the perfect survivor to become obese when highly palatable, energy dense foods are readily available at low energetic cost. It further assures that raised adipose stores are metabolically defended against attempts to lower them. Thus, effective treatment of obesity will only come with a better understanding of the physiological, metabolic, and neurochemical processes that ensure this defense of an elevated body weight.
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Affiliation(s)
- Barry E Levin
- Neurology Service, VA Medical Center, 385 Tremont Avenue, East Orange, NJ 07018-1095, USA.
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Torregrossa AM, Davis JD, Smith GP. Orosensory stimulation is sufficient and postingestive negative feedback is not necessary for neuropeptide Y to increase sucrose intake. Physiol Behav 2006; 87:773-80. [PMID: 16540131 DOI: 10.1016/j.physbeh.2006.01.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Revised: 12/30/2005] [Accepted: 01/20/2006] [Indexed: 11/27/2022]
Abstract
Although central administration of neuropeptide Y (NPY) has a potent orexic effect, it is not clear how NPY changes the potency of peripheral feedbacks from the gut to prolong eating and increase meal size. It has been suggested that NPY increases the stimulating effect of orosensory sweet stimuli or that it decreases the inhibitory effect of postingestive stimuli. To clarify this issue, we compared the orexic effect of NPY (2 microg) injected into the third ventricle of the brain on the volume and microstructure of intake of 0.8M sucrose during sham feeding (SF) and real feeding (RF) in male Sprague Dawley rats. The rationale for this comparison is that orosensory stimulation occurs in SF and RF, but postingestive negative feedback is present only in RF. NPY increased the volume ingested and the rate and number of clusters of licking significantly more in SF than in RF. This demonstrates that orosensory sucrose stimulation is sufficient and postingestive negative feedback is not necessary for the orexic effect of NPY under these experimental conditions.
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Affiliation(s)
- A-M Torregrossa
- Department of Psychiatry, Weill Medical College of Cornell University, USA
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Holland PC, Petrovich GD. A neural systems analysis of the potentiation of feeding by conditioned stimuli. Physiol Behav 2005; 86:747-61. [PMID: 16256152 PMCID: PMC1455527 DOI: 10.1016/j.physbeh.2005.08.062] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2005] [Accepted: 08/25/2005] [Indexed: 11/16/2022]
Abstract
Associative learning processes play many important roles in the control of food consumption. Although these processes can complement regulatory mechanisms in the control of eating by providing opportunities for the anticipation of upcoming needs, they may also contribute to inappropriate or pathological consumption patterns by overriding internal regulatory signals. In this article, we first review some of the ways in which associative learning can contribute to the control of feeding, and then describe a neural systems analysis of a simple animal model of the control of feeding by Pavlovian-conditioned stimuli (CSs). Food-sated rats increase their food consumption after presentation of CSs that were previously paired with food while the rats were food-deprived. This cue-potentiated feeding is independent of conditioned approach responses, and is at least somewhat specific to the foods associated with those CSs. A series of studies that used neuroanatomical tract tracing, immediate early gene expression, and neurotoxic disconnection lesion techniques implicated circuitry that includes the basolateral complex of the amygdala, the lateral hypothalamus, and the medial prefrontal cortex, but not the amygdala central nucleus, nucleus accumbens, or lateral orbitofrontal cortex, in cue-potentiated feeding. These studies also showed dissociations between cue-potentiated feeding and other learned motivational phenomena that are known to depend on function of amygdala systems. The data suggest that cue-potentiated feeding is uniquely mediated by cortical and amygdalar neurons that directly target the lateral hypothalamus, and thus gain access to hypothalamic neuropeptide and other systems involved in the promotion and suppression of eating.
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Affiliation(s)
- Peter C Holland
- Johns Hopkins University, 222 Ames Hall, 3400 North Charles St., Baltimore, MD 21218, USA.
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Sindelar DK, Palmiter RD, Woods SC, Schwartz MW. Attenuated feeding responses to circadian and palatability cues in mice lacking neuropeptide Y. Peptides 2005; 26:2597-602. [PMID: 15923061 DOI: 10.1016/j.peptides.2005.04.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Revised: 04/27/2005] [Accepted: 04/28/2005] [Indexed: 11/15/2022]
Abstract
Neuropeptide Y (NPY) is a potent orexigenic peptide that is implicated in the feeding response to a variety of stimuli. The current studies employed mice lacking NPY (Npy-/-) and their wild-type (Npy+/+) littermates to investigate the role of this peptide in the feeding response to circadian and palatability cues. To investigate the response to a circadian stimulus, we assessed food intake during the 4-h period following dark onset, a time of day characterized by maximal rates of food consumption. Compared to Npy+/+ controls, intake of Npy-/- mice was reduced by 33% during this period (0.6+/-0.1g versus 0.9+/-0.1g; p<or=0.05). In contrast, intake did not differ between genotypes when measured over a 24-h period (3.7+/-0.2g versus 3.5+/-0.3g; p=ns). Furthermore, reduced dark cycle 4h food intake in Npy-/- mice was not evident after a 24-h fast (1.4+/-0.1g for both genotypes; p=ns), despite a pronounced delay in the initiation of feeding (636+/-133 s versus 162+/-29 s; p<or=0.05). To investigate the role of NPY in the feeding response to palatability cues, mice were presented with a highly palatable diet (HP) for 1h each day (in addition to having ad libitum access to chow) for 18 days. Npy+/+ mice rapidly increased daily HP intake such that by the end of the first week, they derived a substantial fraction of daily energy from this source (41+/-3%). By comparison, HP intake was markedly reduced in Npy-/- mice during the first week (24+/-7% of daily energy intake, p<or=0.05 versus Npy+/+), although it eventually increased (by Day 9) to values comparable to those of Npy+/+ controls. These experiments suggest that NPY contributes to the mechanism whereby food intake increases in response to circadian and palatability cues and that mechanisms driving food intake in response to these stimuli differ from those activated by energy restriction.
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Affiliation(s)
- Dana K Sindelar
- Department of Medicine, University of Washington, Harborview Hospital, Division of Endocrinology, Box 359757, 325 9th Avenue, Seattle, WA 98104, USA
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