1
|
Mekjavic IB, Amon M, Simpson EJ, Kölegård R, Eiken O, Macdonald IA. Energy Intake of Men With Excess Weight During Normobaric Hypoxic Confinement. Front Physiol 2022; 12:801833. [PMID: 35095562 PMCID: PMC8790566 DOI: 10.3389/fphys.2021.801833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 12/16/2021] [Indexed: 11/13/2022] Open
Abstract
Due to the observations of weight loss at high altitude, normobaric hypoxia has been considered as a method of weight loss in obese individuals. With this regard, the aim of the present study was to determine the effect of hypoxia per se on metabolism in men with excess weight. Eight men living with excess weight (125.0 ± 17.7 kg; 30.5 ± 11.1 years, BMI: 37.6 ± 6.2 kg⋅m-2) participated in a randomized cross-over study comprising two 10-day confinements: normobaric (altitude of facility ≃ 940 m) normoxia (NORMOXIA; P I O2 = 133 mmHg), and normobaric hypoxia (HYPOXIA). The P I O2 in the latter was reduced from 105 (simulated altitude of 2,800 m) to 98 mmHg (simulated altitude of 3,400 m over 10 days. Before, and at the end of each confinement, participants completed a meal tolerance test (MTT). Resting energy expenditure (REE), circulating glucose, GLP-1, insulin, catecholamines, ghrelin, peptide-YY (PYY), leptin, gastro-intestinal blood flow, and appetite sensations were measured in fasted and postprandial states. Fasting REE increased after HYPOXIA (+358.0 ± 49.3 kcal⋅day-1, p = 0.03), but not after NORMOXIA (-33.1 ± 17.6 kcal⋅day-1). Postprandial REE was also significantly increased after HYPOXIA (p ≤ 0.05), as was the level of PYY. Furthermore, a tendency for decreased energy intake was concomitant with a significant body weight reduction after HYPOXIA (-0.7 ± 0.2 kg) compared to NORMOXIA (+1.0 ± 0.2 kg). The HYPOXIA trial increased the metabolic requirements, with a tendency toward decreased energy intake concomitant with increased PYY levels supporting the notion of a hypoxia-induced appetite inhibition, that could potentially lead to body weight reduction. The greater postprandial blood-glucose response following hypoxic confinement, suggests the potential development of insulin resistance.
Collapse
Affiliation(s)
- Igor B. Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Mojca Amon
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Elizabeth J. Simpson
- Metabolic and Molecular Physiology Group, Faculty of Medicine and Health Sciences University of Nottingham Queen’s Medical Centre, Nottingham, United Kingdom
| | - Roger Kölegård
- Division of Environmental Physiology, School of Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Ola Eiken
- Division of Environmental Physiology, School of Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Ian A. Macdonald
- Metabolic and Molecular Physiology Group, Faculty of Medicine and Health Sciences University of Nottingham Queen’s Medical Centre, Nottingham, United Kingdom
| |
Collapse
|
2
|
Lawson EA, Olszewski PK, Weller A, Blevins JE. The role of oxytocin in regulation of appetitive behaviour, body weight and glucose homeostasis. J Neuroendocrinol 2020; 32:e12805. [PMID: 31657509 PMCID: PMC7186135 DOI: 10.1111/jne.12805] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 10/14/2019] [Accepted: 10/24/2019] [Indexed: 12/28/2022]
Abstract
Obesity and its associated complications have reached epidemic proportions in the USA and also worldwide, highlighting the need for new and more effective treatments. Although the neuropeptide oxytocin (OXT) is well recognised for its peripheral effects on reproductive behaviour, the release of OXT from somatodendrites and axonal terminals within the central nervous system (CNS) is also implicated in the control of energy balance. In this review, we summarise historical data highlighting the effects of exogenous OXT as a short-term regulator of food intake in a context-specific manner and the receptor populations that may mediate these effects. We also describe what is known about the physiological role of endogenous OXT in the control of energy balance and whether serum and brain levels of OXT relate to obesity on a consistent basis across animal models and humans with obesity. We describe recent data on the effectiveness of chronic CNS administration of OXT to decrease food intake and weight gain or to elicit weight loss in diet-induced obese (DIO) and genetically obese mice and rats. Of clinical importance is the finding that chronic central and peripheral OXT treatments both evoke weight loss in obese animal models with impaired leptin signalling at doses that are not associated with visceral illness, tachyphylaxis or adverse cardiovascular effects. Moreover, these results have been largely recapitulated following chronic s.c. or intranasal treatment in DIO non-human primates (rhesus monkeys) and obese humans, respectively. We also identify plausible mechanisms that contribute to the effects of OXT on body weight and glucose homeostasis in rodents, non-human primates and humans. We conclude by describing the ongoing challenges that remain before OXT-based therapeutics can be used as a long-term strategy to treat obesity in humans.
Collapse
Affiliation(s)
- Elizabeth A Lawson
- Neuroendocrine Unit, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Pawel K Olszewski
- Faculty of Science and Engineering, University of Waikato, Hamilton, New Zealand
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, Minneapolis, MN, USA
| | - Aron Weller
- Psychology Department and Gonda Brain Research Center, Bar Ilan University, Ramat-Gan, Israel
| | - James E Blevins
- Department of Veterans Affairs Medical Center, Office of Research and Development Medical Research Service, VA Puget Sound Health Care System, Seattle, WA, USA
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
| |
Collapse
|
3
|
Berner LA, Brown TA, Lavender JM, Lopez E, Wierenga CE, Kaye WH. Neuroendocrinology of reward in anorexia nervosa and bulimia nervosa: Beyond leptin and ghrelin. Mol Cell Endocrinol 2019; 497:110320. [PMID: 30395874 PMCID: PMC6497565 DOI: 10.1016/j.mce.2018.10.018] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 10/19/2018] [Accepted: 10/27/2018] [Indexed: 12/14/2022]
Abstract
The pathophysiology of anorexia nervosa (AN) and bulimia nervosa (BN) are still poorly understood, but psychobiological models have proposed a key role for disturbances in the neuroendocrines that signal hunger and satiety and maintain energy homeostasis. Mounting evidence suggests that many neuroendocrines involved in the regulation of homeostasis and body weight also play integral roles in food reward valuation and learning via their interactions with the mesolimbic dopamine system. Neuroimaging data have associated altered brain reward responses in this system with the dietary restriction and binge eating and purging characteristic of AN and BN. Thus, neuroendocrine dysfunction may contribute to or perpetuate eating disorder symptoms via effects on reward circuitry. This narrative review focuses on reward-related neuroendocrines that are altered in eating disorder populations, including peptide YY, insulin, stress and gonadal hormones, and orexins. We provide an overview of the animal and human literature implicating these neuroendocrines in dopaminergic reward processes and discuss their potential relevance to eating disorder symptomatology and treatment.
Collapse
Affiliation(s)
- Laura A Berner
- University of California, San Diego, Eating Disorders Center for Treatment and Research, Department of Psychiatry, United States.
| | - Tiffany A Brown
- University of California, San Diego, Eating Disorders Center for Treatment and Research, Department of Psychiatry, United States
| | - Jason M Lavender
- University of California, San Diego, Eating Disorders Center for Treatment and Research, Department of Psychiatry, United States
| | - Emily Lopez
- University of California, San Diego, Eating Disorders Center for Treatment and Research, Department of Psychiatry, United States
| | - Christina E Wierenga
- University of California, San Diego, Eating Disorders Center for Treatment and Research, Department of Psychiatry, United States
| | - Walter H Kaye
- University of California, San Diego, Eating Disorders Center for Treatment and Research, Department of Psychiatry, United States
| |
Collapse
|
4
|
Jones ES, Nunn N, Chambers AP, Østergaard S, Wulff BS, Luckman SM. Modified Peptide YY Molecule Attenuates the Activity of NPY/AgRP Neurons and Reduces Food Intake in Male Mice. Endocrinology 2019; 160:2737-2747. [PMID: 31074796 PMCID: PMC6806261 DOI: 10.1210/en.2019-00100] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 05/06/2019] [Indexed: 01/15/2023]
Abstract
To study the effects of an analog of the gut-produced hormone peptide YY (PYY3-36), which has increased selectivity for the Y2 receptor; specifically, to record its effects on food intake and on hypothalamic neuropeptide Y/agouti-related peptide (NPY/AgRP) neuron activity. NNC0165-1273, a modified form of the peptide hormone PYY3-36 with potent selectivity at Y2 receptor (>5000-fold over Y1, 1250-fold over Y4, and 650-fold over Y5 receptor), was tested in vivo and in vitro in mouse models. NNC0165-1273 has fivefold lower relative affinity for Y2 compared with PYY3-36, but >250-, 192-, and 400-fold higher selectivity, respectively, for the Y1, Y4, and Y5 receptors. NNC0165-1273 produced a reduction in nighttime feeding at a dose at which PYY3-36 loses efficacy. The normal behavioral satiety sequence observed suggests that NNC0165-1273 is not nauseating and, instead, reduces food intake by producing early satiety. Additionally, NNC0165-1273 blocked ghrelin-induced cFos expression in NPY/AgRP neurons. In vitro electrophysiological recordings showed that, opposite to ghrelin, NNC0165-1273 hyperpolarized NPY/AgRP neurons and reduced action potential frequency. Administration of NNC0165-1273 via subcutaneous osmotic minipump caused a dose-dependent decrease in body weight and fat mass in an obese mouse model. Finally, NNC0165-1273 attenuated the feeding response when NPY/AgRP neurons were activated using ghrelin or more selectively with designer receptors. NNC0165-1273 is nonnauseating and stimulates a satiety response through, at least in part, a direct action on hypothalamic NPY/AgRP neurons. Modification of PYY3-36 to produce compounds with increased affinity to Y2 receptors may be useful as antiobesity therapies in humans.
Collapse
Affiliation(s)
- Edward S Jones
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Nicolas Nunn
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Adam P Chambers
- GLP-1 & T2D Pharmacology, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Søren Østergaard
- Research Chemistry 2, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Birgitte S Wulff
- Obesity Research, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Simon M Luckman
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| |
Collapse
|
5
|
Martin AM, Sun EW, Rogers GB, Keating DJ. The Influence of the Gut Microbiome on Host Metabolism Through the Regulation of Gut Hormone Release. Front Physiol 2019; 10:428. [PMID: 31057420 PMCID: PMC6477058 DOI: 10.3389/fphys.2019.00428] [Citation(s) in RCA: 184] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 03/27/2019] [Indexed: 12/17/2022] Open
Abstract
The microbial community of the gut conveys significant benefits to host physiology. A clear relationship has now been established between gut bacteria and host metabolism in which microbial-mediated gut hormone release plays an important role. Within the gut lumen, bacteria produce a number of metabolites and contain structural components that act as signaling molecules to a number of cell types within the mucosa. Enteroendocrine cells within the mucosal lining of the gut synthesize and secrete a number of hormones including CCK, PYY, GLP-1, GIP, and 5-HT, which have regulatory roles in key metabolic processes such as insulin sensitivity, glucose tolerance, fat storage, and appetite. Release of these hormones can be influenced by the presence of bacteria and their metabolites within the gut and as such, microbial-mediated gut hormone release is an important component of microbial regulation of host metabolism. Dietary or pharmacological interventions which alter the gut microbiome therefore pose as potential therapeutics for the treatment of human metabolic disorders. This review aims to describe the complex interaction between intestinal microbiota and their metabolites and gut enteroendocrine cells, and highlight how the gut microbiome can influence host metabolism through the regulation of gut hormone release.
Collapse
Affiliation(s)
- Alyce M Martin
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Emily W Sun
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Geraint B Rogers
- Microbiome Research Laboratory, Flinders University, Adelaide, SA, Australia.,Infection and Immunity, South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Damien J Keating
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia.,Nutrition and Metabolism, South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| |
Collapse
|
6
|
Zapata RC, McMillan C, Tong J, Chelikani PK. Short communication: Expression of transcripts for proglucagon, glucose-dependent insulinotropic peptide, peptide YY, and their cognate receptors, in feline peripheral tissues. Res Vet Sci 2019; 124:223-227. [PMID: 30928654 DOI: 10.1016/j.rvsc.2019.03.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/22/2019] [Accepted: 03/24/2019] [Indexed: 12/26/2022]
Abstract
Gastrointestinal hormone based therapies are being investigated for treating diabetes in cats; however, the tissue distribution of these hormones and their cognate receptors remain largely understudied. We determined the distribution of transcripts for the gut hormones proglucagon (Gcg), glucose-dependent insulinotropic peptide (Gip), peptide YY (Pyy), and their receptors (Glp1r, Gipr, Npy2r), in feline peripheral tissues. The Gcg, Gip and Pyy mRNA were expressed in the gut, with higher Gcg and Pyy abundance in the lower gut. Interestingly, Glp1r and Npy2r mRNA were expressed in multiple peripheral tissues including the gut, pancreas and liver, whereas, Gipr mRNA was restricted to the stomach and adipose tissues. The localized mRNA expression of Gcg and Pyy in the gut, but the extensive distribution of Glp1r and Npy2r in several peripheral tissues suggests that these hormones may have pleiotropic physiological functions in cats.
Collapse
Affiliation(s)
- Rizaldy C Zapata
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, Alberta T2N 4N1, Canada
| | - Chantal McMillan
- Department of Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, Alberta T2N 4N1, Canada
| | - Jesse Tong
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, Alberta T2N 4N1, Canada
| | - Prasanth K Chelikani
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, Alberta T2N 4N1, Canada; Gastrointestinal Research Group, Snyder Institute for Chronic Diseases, University of Calgary, 3330 Hospital Dr. NW, Calgary, Alberta T2N 4N1, Canada.
| |
Collapse
|
7
|
Martin AM, Sun EW, Rogers GB, Keating DJ. The Influence of the Gut Microbiome on Host Metabolism Through the Regulation of Gut Hormone Release. Front Physiol 2019. [PMID: 31057420 DOI: 10.3389/fphys.2019.00428/bibtex] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023] Open
Abstract
The microbial community of the gut conveys significant benefits to host physiology. A clear relationship has now been established between gut bacteria and host metabolism in which microbial-mediated gut hormone release plays an important role. Within the gut lumen, bacteria produce a number of metabolites and contain structural components that act as signaling molecules to a number of cell types within the mucosa. Enteroendocrine cells within the mucosal lining of the gut synthesize and secrete a number of hormones including CCK, PYY, GLP-1, GIP, and 5-HT, which have regulatory roles in key metabolic processes such as insulin sensitivity, glucose tolerance, fat storage, and appetite. Release of these hormones can be influenced by the presence of bacteria and their metabolites within the gut and as such, microbial-mediated gut hormone release is an important component of microbial regulation of host metabolism. Dietary or pharmacological interventions which alter the gut microbiome therefore pose as potential therapeutics for the treatment of human metabolic disorders. This review aims to describe the complex interaction between intestinal microbiota and their metabolites and gut enteroendocrine cells, and highlight how the gut microbiome can influence host metabolism through the regulation of gut hormone release.
Collapse
Affiliation(s)
- Alyce M Martin
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Emily W Sun
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
| | - Geraint B Rogers
- Microbiome Research Laboratory, Flinders University, Adelaide, SA, Australia
- Infection and Immunity, South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Damien J Keating
- Molecular and Cellular Physiology Laboratory, College of Medicine and Public Health, Flinders University, Adelaide, SA, Australia
- Nutrition and Metabolism, South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| |
Collapse
|
8
|
Abstract
In moderately or morbidly obese patients, bariatric surgery has been proven to be an effective therapeutic approach to control body weight and comorbidities. Surgery-mediated modulation of brain function via modified postoperative secretion of gut peptides and vagal nerve stimulation was identified as an underlying mechanism in weight loss and improvement of weight-related diseases. Increased basal and postprandial plasma levels of gastrointestinal hormones like glucagon-like peptide 1 and peptide YY that act on specific areas of the hypothalamus to reduce food intake, either directly or mediated by the vagus nerve, are observed after surgery while suppression of meal-induced ghrelin release is increased. Hormones released from the adipose tissue like leptin and adiponectin are also affected and leptin plasma levels are reduced in treated patients. Besides homeostatic control of body weight, surgery also changes hedonistic behavior in regard to food intake and cognitive performance involving the limbic system and prefrontal areas.
Collapse
|
9
|
Shen WJ, Yao T, Kong X, Williams KW, Liu T. Melanocortin neurons: Multiple routes to regulation of metabolism. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2477-85. [PMID: 28499988 DOI: 10.1016/j.bbadis.2017.05.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 03/31/2017] [Accepted: 05/05/2017] [Indexed: 01/07/2023]
Abstract
The burden of disability, premature death, escalating health care costs and lost economic productivity due to obesity and its associated complications including hypertension, stroke, cardiovascular disease and type 2 diabetes is staggering [1,2]. A better understanding of metabolic homeostatic pathways will provide us with insights into the biological mechanisms of obesity and how to fundamentally address this epidemic [3-6]. In mammals, energy balance is maintained via a homeostatic system involving both peripheral and central melanocortin systems; changes in body weight reflect an unbalance of the energetic state [7-9]. Although the primary cause of obesity is unknown, there is significant effort to understand the role of the central melanocortin pathway in the brain as it has been shown that deficiency of proopiomelanocortin (POMC) [10,11] and melanocortin 4 receptors (MC4R) [12-15] in both rodents and humans results in severe hyperphagia and obesity [16-23]. In this review, we will summarize how the central melanocortin pathway helps regulate body mass and adiposity within a 'healthy' range through the 'nutrient sensing' network [24-28]. This article is part of a Special Issue entitled: Melanocortin Receptors - edited by Ya-Xiong Tao.
Collapse
|
10
|
Affiliation(s)
- Georgios Valsamakis
- Unit of Endocrinology, Diabetes Mellitus and Metabolism, Aretaieio University Hospital, Athens Medical School, Athens 11528, Greece; , ,
| | - Panagiota Konstantakou
- Unit of Endocrinology, Diabetes Mellitus and Metabolism, Aretaieio University Hospital, Athens Medical School, Athens 11528, Greece; , ,
| | - George Mastorakos
- Unit of Endocrinology, Diabetes Mellitus and Metabolism, Aretaieio University Hospital, Athens Medical School, Athens 11528, Greece; , ,
| |
Collapse
|
11
|
Abstract
The gastrointestinal (GI) tract senses the ingestion of food and responds by signaling to the brain to promote satiation and satiety. Representing an important part of the gut-brain axis, enteroendocrine L-cells secrete the anorectic peptide hormones glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) in response to the ingestion of food. The release of GLP-1 has multiple effects, including the secretion of insulin from pancreatic β-cells, decreased gastric emptying, and increased satiation. PYY also slows GI motility and reduces food intake. At least part of the gut-brain response seems to be due to direct sensing of macronutrients by L-cells, by mechanisms including specific nutrient-sensing receptors. Such receptors may represent possible pathways to target to decrease appetite and increase energy expenditure. Designing drugs or functional foods to exploit the machinery of these nutrient-sensing mechanisms may offer a potential approach for agents to treat obesity and metabolic disease.
Collapse
Affiliation(s)
- Eleanor Spreckley
- Section of Investigative Medicine, Department of Medicine, Imperial College London, Hammersmith Hospital , London , UK
| | - Kevin Graeme Murphy
- Section of Investigative Medicine, Department of Medicine, Imperial College London, Hammersmith Hospital , London , UK
| |
Collapse
|
12
|
Kuehl PJ, Boyden T, Dobry DE, Doyle-Eisele M, Friesen DT, McDonald JD, Murri BG, Vodak DT, Lyon DK. Inhaled PYY(3-36) dry-powder formulation for appetite suppression. Drug Dev Ind Pharm 2015; 42:150-156. [PMID: 26006332 DOI: 10.3109/03639045.2015.1036067] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Peptide YY3-36 [PYY(3-36)] has shown efficacy in appetite suppression when dosed by injection modalities (intraperitoneal (IP)/subcutaneous). Transitioning to needle-free delivery, towards inhalation, often utilizes systemic pharmacokinetics as a key endpoint to compare different delivery methods and doses. Systemic pharmacokinetics were evaluated for PYY3-36 when delivered by IP, subcutaneous, and inhalation, the systemic pharmacokinetics were then used to select doses in an appetite suppression pharmacodynamic study. METHODS Dry-powder formulations were manufactured by spray drying and delivered to mice via nose only inhalation. The systemic plasma, lung tissue, and bronchoalveolar lavage fluid pharmacokinetics of different inhalation doses of PYY(3-36) were compared to IP and subcutaneous efficacious doses. Based on these pharmacokinetic data, inhalation doses of 70:30 PYY(3-36):Dextran T10 were evaluated in a mouse model of appetite suppression and compared to IP and subcutaneous data. RESULTS Inhalation pharmacokinetic studies showed that plasma exposure was similar for a 2 × higher inhalation dose when compared to subcutaneous and IP delivery. Inhalation doses of 0.22 and 0.65 mg/kg were for efficacy studies. The results showed a dose-dependent (not dose proportional) decrease in food consumption over 4 h, which is similar to IP and subcutaneous delivery routes. CONCLUSIONS The pharmacokinetic and pharmacodynamics results substantiate the ability of pharmacokinetic data to inform pharmacodynamics dose selection for inhalation delivery of the peptide PYY(3-36). Additionally, engineered PYY(3-36):Dextran T10 particles delivered to the respiratory tract show promise as a non-invasive therapeutic for appetite suppression.
Collapse
Affiliation(s)
- Philip J Kuehl
- a Lovelace Respiratory Research Institute , Albuquerque , NM , USA
| | | | | | | | | | - Jacob D McDonald
- a Lovelace Respiratory Research Institute , Albuquerque , NM , USA
| | | | | | | |
Collapse
|
13
|
Blevins JE, Baskin DG. Translational and therapeutic potential of oxytocin as an anti-obesity strategy: Insights from rodents, nonhuman primates and humans. Physiol Behav 2015; 152:438-49. [PMID: 26013577 DOI: 10.1016/j.physbeh.2015.05.023] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 05/19/2015] [Accepted: 05/21/2015] [Indexed: 12/15/2022]
Abstract
The fact that more than 78 million adults in the US are considered overweight or obese highlights the need to develop new, effective strategies to treat obesity and its associated complications, including type 2 diabetes, kidney disease and cardiovascular disease. While the neurohypophyseal peptide oxytocin (OT) is well recognized for its peripheral effects to stimulate uterine contraction during parturition and milk ejection during lactation, release of OT within the brain is implicated in prosocial behaviors and in the regulation of energy balance. Previous findings indicate that chronic administration of OT decreases food intake and weight gain or elicits weight loss in diet-induced obese (DIO) mice and rats. Furthermore, chronic systemic treatment with OT largely reproduces the effects of central administration to reduce weight gain in DIO and genetically obese rodents at doses that do not appear to result in tolerance. These findings have now been recently extended to more translational models of obesity showing that chronic subcutaneous or intranasal OT treatment is sufficient to elicit body weight loss in DIO nonhuman primates and pre-diabetic obese humans. This review assesses the potential use of OT as a therapeutic strategy for treatment of obesity in rodents, nonhuman primates, and humans, and identifies potential mechanisms that mediate this effect.
Collapse
Affiliation(s)
- James E Blevins
- VA Puget Sound Health Care System, Office of Research and Development, Medical Research Service, Department of Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA; Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA.
| | - Denis G Baskin
- VA Puget Sound Health Care System, Office of Research and Development, Medical Research Service, Department of Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA; Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
| |
Collapse
|
14
|
Henry KE, Elfers CT, Burke RM, Chepurny OG, Holz GG, Blevins JE, Roth CL, Doyle RP. Vitamin B12 conjugation of peptide-YY(3-36) decreases food intake compared to native peptide-YY(3-36) upon subcutaneous administration in male rats. Endocrinology 2015; 156:1739-49. [PMID: 25658456 PMCID: PMC4398759 DOI: 10.1210/en.2014-1825] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Challenges to peptide-based therapies include rapid clearance, ready degradation by hydrolysis/proteolysis, and poor intestinal uptake and/or a need for blood brain barrier transport. This work evaluates the efficacy of conjugation of vitamin B12 (B12) on sc administered peptide tyrosine tyrosine (PYY)(3-36) function. In the current experiments, a B12-PYY(3-36) conjugate was tested against native PYY(3-36), and an inactive conjugate B12-PYYC36 (null control) in vitro and in vivo. In vitro experiments demonstrated similar agonism for the neuropeptide Y2 receptor by the B12-PYY(3-36) conjugate (EC50 26.5 nM) compared with native PYY(3-36) (EC50 16.0 nM), with the null control having an EC50 of 1.8 μM. In vivo experiments were performed in young adult male Sprague Dawley rats (9 wk). Daily treatments were delivered sc in five 1-hour pulses, each pulse delivering 5-10 nmol/kg, by implanted microinfusion pumps. Increases in hindbrain Fos expression were comparable 90 minutes after B12-PYY(3-36) or PYY3-36 injection relative to saline or B12-PYYC36. Food intake was reduced during a 5-day treatment for both B12-PYY(3-36)- (24%, P = .001) and PYY(3-36)-(13%, P = .008) treated groups relative to baseline. In addition, reduction of food intake after the three dark cycle treatment pulses was more consistent with B12-PYY(3-36) treatment (-26%, -29%, -27%) compared with the PYY(3-36) treatment (-3%, -21%, -16%), and B12-PYY(3-36) generated a significantly longer inhibition of food intake vs. PYY(3-36) treatment after the first two pulses (P = .041 and P = .036, respectively). These findings demonstrate a stronger, more consistent, and longer inhibition of food intake after the pulses of B12-PYY(3-36) conjugate compared with the native PYY(3-36).
Collapse
Affiliation(s)
- Kelly E Henry
- Department of Chemistry (K.E.H., R.M.B., R.P.D.), Center for Science and Technology, Syracuse University, Syracuse, New York 13244; Center for Integrative Brain Research (C.T.E., C.L.R.), Division of Endocrinology, Seattle Children's Research Institute, Seattle, Washington 98101; Departments of Medicine (O.G.C., G.G.H., R.P.D.) and Pharmacology (G.G.H.), State University of New York, Upstate Medical University, Syracuse, New York 13210; Research and Development Service (J.E.B.), Veterans Affairs Puget Sound Health Care System, Seattle, Washington 98108; Department of Medicine (J.E.B.), Division of Metabolism, Endocrinology, and Nutrition, University of Washington, Seattle, Washington 98195; and Division of Endocrinology (C.L.R.), Department of Pediatrics, University of Washington, Seattle, Washington 98105
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Reidelberger R, Haver A, Anders K, Apenteng B. Role of capsaicin-sensitive peripheral sensory neurons in anorexic responses to intravenous infusions of cholecystokinin, peptide YY-(3-36), and glucagon-like peptide-1 in rats. Am J Physiol Endocrinol Metab 2014; 307:E619-29. [PMID: 25117406 PMCID: PMC4200310 DOI: 10.1152/ajpendo.00024.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cholecystokinin (CCK)-induced suppression of feeding is mediated by vagal sensory neurons that are destroyed by the neurotoxin capsaicin (CAP). Here we determined whether CAP-sensitive neurons mediate anorexic responses to intravenous infusions of gut hormones peptide YY-(3-36) [PYY-(3-36)] and glucagon-like peptide-1 (GLP-1). Rats received three intraperitoneal injections of CAP or vehicle (VEH) in 24 h. After recovery, non-food-deprived rats received at dark onset a 3-h intravenous infusion of CCK-8 (5, 17 pmol·kg⁻¹·min⁻¹), PYY-(3-36) (5, 17, 50 pmol·kg⁻¹·min⁻¹), or GLP-1 (17, 50 pmol·kg⁻¹·min⁻¹). CCK-8 was much less effective in reducing food intake in CAP vs. VEH rats. CCK-8 at 5 and 17 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 39 and 71% in VEH rats and 7 and 18% in CAP rats. In contrast, PYY-(3-36) and GLP-1 were similarly effective in reducing food intake in VEH and CAP rats. PYY-(3-36) at 5, 17, and 50 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 15, 33, and 70% in VEH rats and 13, 30, and 33% in CAP rats. GLP-1 at 17 and 50 pmol·kg⁻¹·min⁻¹ reduced food intake during the 3-h infusion period by 48 and 60% in VEH rats and 30 and 52% in CAP rats. These results suggest that anorexic responses to PYY-(3-36) and GLP-1 are not primarily mediated by the CAP-sensitive peripheral sensory neurons (presumably vagal) that mediate CCK-8-induced anorexia.
Collapse
MESH Headings
- Animals
- Anorexia/metabolism
- Anorexia/physiopathology
- Anorexia/prevention & control
- Behavior, Animal/drug effects
- Capsaicin/administration & dosage
- Capsaicin/toxicity
- Cholecystokinin/administration & dosage
- Cholecystokinin/metabolism
- Disease Models, Animal
- Energy Intake/drug effects
- Feeding Behavior/drug effects
- Glucagon-Like Peptide 1/administration & dosage
- Glucagon-Like Peptide 1/metabolism
- Infusions, Intravenous
- Injections, Intraperitoneal
- Intestinal Mucosa/drug effects
- Intestinal Mucosa/innervation
- Intestinal Mucosa/metabolism
- Intestinal Mucosa/physiopathology
- Intestine, Small/drug effects
- Intestine, Small/innervation
- Intestine, Small/metabolism
- Intestine, Small/physiopathology
- Male
- Neuritis/chemically induced
- Neuritis/metabolism
- Neuritis/physiopathology
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Peptide Fragments/administration & dosage
- Peptide Fragments/metabolism
- Peptide YY/administration & dosage
- Peptide YY/metabolism
- Rats
- Vagus Nerve/drug effects
- Vagus Nerve/metabolism
- Vagus Nerve/physiopathology
- Vagus Nerve Diseases/chemically induced
- Vagus Nerve Diseases/metabolism
- Vagus Nerve Diseases/physiopathology
Collapse
Affiliation(s)
- Roger Reidelberger
- Veterans Affairs Research Service, Veterans Affairs Nebraska Western Iowa Health Care System, Omaha, Nebraska; and Department of Biomedical Sciences, Creighton University, Omaha, Nebraska
| | - Alvin Haver
- Veterans Affairs Research Service, Veterans Affairs Nebraska Western Iowa Health Care System, Omaha, Nebraska; and Department of Biomedical Sciences, Creighton University, Omaha, Nebraska
| | - Krista Anders
- Department of Biomedical Sciences, Creighton University, Omaha, Nebraska
| | - Bettye Apenteng
- Department of Biomedical Sciences, Creighton University, Omaha, Nebraska
| |
Collapse
|
16
|
Ye J, Hao Z, Mumphrey MB, Townsend RL, Patterson LM, Stylopoulos N, Münzberg H, Morrison CD, Drucker DJ, Berthoud HR. GLP-1 receptor signaling is not required for reduced body weight after RYGB in rodents. Am J Physiol Regul Integr Comp Physiol 2014; 306:R352-62. [PMID: 24430883 DOI: 10.1152/ajpregu.00491.2013] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Exaggerated GLP-1 and PYY secretion is thought to be a major mechanism in the reduced food intake and body weight after Roux-en-Y gastric bypass surgery. Here, we use complementary pharmacological and genetic loss-of-function approaches to test the role of increased signaling by these gut hormones in high-fat diet-induced obese rodents. Chronic brain infusion of a supramaximal dose of the selective GLP-1 receptor antagonist exendin-9-39 into the lateral cerebral ventricle significantly increased food intake and body weight in both RYGB and sham-operated rats, suggesting that, while contributing to the physiological control of food intake and body weight, central GLP-1 receptor signaling tone is not the critical mechanism uniquely responsible for the body weight-lowering effects of RYGB. Central infusion of the selective Y2R-antagonist BIIE0246 had no effect in either group, suggesting that it is not critical for the effects of RYGB on body weight under the conditions tested. In a recently established mouse model of RYGB that closely mimics surgery and weight loss dynamics in humans, obese GLP-1R-deficient mice lost the same amount of body weight and fat mass and maintained similarly lower body weight compared with wild-type mice. Together, the results surprisingly provide no support for important individual roles of either gut hormone in the specific mechanisms by which RYGB rats settle at a lower body weight. It is likely that the beneficial effects of bariatric surgeries are expressed through complex mechanisms that require combination approaches for their identification.
Collapse
Affiliation(s)
- Jianping Ye
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Abstract
Over the past 30 years, it has been established that hormones produced by the gut, pancreas, and adipose tissue are key players in the control of body weight. These hormones act through a complex neuroendocrine system, including the hypothalamus, to regulate metabolism and energy homeostasis. In obesity, this homeostatic balance is disrupted, either through alterations in the levels of these hormones or through resistance to their actions. Alterations in gut hormone secretion following gastric bypass surgery are likely to underlie the dramatic and persistent loss of weight following this procedure, as well as the observed amelioration in type 2 diabetes mellitus. Medications based on the gut hormone GLP-1 are currently in clinical use to treat type 2 diabetes mellitus and have been shown to produce weight loss. Further therapies for obesity based on other gut hormones are currently in development.
Collapse
Affiliation(s)
- Rebecca Scott
- Division of Diabetes, Endocrinology, Metabolism, Hammersmith Hospital, Imperial College London, London, United Kingdom.
| | | | | |
Collapse
|
18
|
Albertsen L, Shaw AC, Norrild JC, Strømgaard K. Recombinant production of peptide C-terminal α-amides using an engineered intein. Bioconjug Chem 2013; 24:1883-94. [PMID: 24138202 DOI: 10.1021/bc4002689] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Peptides are of increasing interest as therapeutics in a wide range of diseases, including metabolic diseases such as diabetes and obesity. In the latter, peptide hormones such as peptide YY (PYY) and pancreatic peptide (PP) are important templates for drug design. Characteristic for these peptides is that they contain a C-terminal that is α-amidated, and this amidation is crucial for biological function. A challenge is to generate such peptides by recombinant means and particularly in a production scale. Here, we have examined an intein-mediated approach to generate a PYY derivative in a larger scale. Initially, we experienced challenges with hydrolysis of the intein fusion protein, which was reduced by a T3C mutation in the intein. Subsequently, we further engineered the intein to decrease the absolute size and improve the relative yield of the PYY derivative, which was achieved by substituting 54 residues of the 198 amino acid intein with an eight amino acid linker. The optimized intein construct was used to produce the PYY derivative under high cell density cultivation conditions, generating the peptide thioester precursor in good yields and subsequent amidation provided the target peptide.
Collapse
|
19
|
Abstract
Diabetes is a major and growing public health challenge which threatens to overwhelm medical services in the future. Type 2 diabetes confers significant morbidity and mortality, most notably with target organ damage to the eyes, kidneys, nerves and heart. The magnitude of cardiovascular risk associated with diabetes is best illustrated by its position as a coronary heart disease risk equivalent. Complications related to neuropathy are also vast, often working in concert with vascular abnormalities and resulting in serious clinical consequences such as foot ulceration. Increased understanding of the natural history of this disorder has generated the potential to intervene and halt pathological progression before overt disease ensues, after which point management becomes increasingly challenging. The concept of prediabetes as a formal diagnosis has begun to be translated from the research setting to clinical practice, but with continually updated guidelines, varied nomenclature, emerging pharmacotherapies and an ever-changing evidence base, clinicians may be left uncertain of best practice in identifying and managing patients at the prediabetic stage. This review aims to summarize the epidemiological data, new concepts in disease pathogenesis and guideline recommendations in addition to lifestyle, pharmacological and surgical therapies targeted at stopping progression of prediabetes to diabetes. While antidiabetic medications, with newer anti-obesity medications and interventional bariatric procedures have shown some promising benefits, diet and therapeutic lifestyle change remains the mainstay of management to improve the metabolic profile of individuals with glucose dysregulation. New risk stratification tools to identify at-risk individuals, coupled with unselected population level intervention hold promise in future practice.
Collapse
Affiliation(s)
- Kaivan Khavandi
- BHF Centre of Excellence in Cardiovascular Research, The Rayne Institute, Department of Cardiology, King's College London, St Thomas' Hospital, Westminster Palace Road, London SE1 7EH, UK
| | | | | | | |
Collapse
|
20
|
Sun D, Liu S, Zhang G, Chen W, Yan Z, Hu S. Type 2 diabetes control in a nonobese rat model using sleeve gastrectomy with duodenal-jejunal bypass (SGDJB). Obes Surg 2013; 22:1865-73. [PMID: 22911149 DOI: 10.1007/s11695-012-0744-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND As a new bariatric procedure, sleeve gastrectomy with duodenal-jejunal bypass (SGDJB) needs further assessment. We compared the diabetic control between SGDJB and sleeve gastrectomy (SG) in Goto-Kakizaki (GK) rats, a nonobese rat model of type 2 diabetes. Our aim is firstly to develop a nonobese diabetic rat model for SGDJB and secondly to investigate the feasibility and safety of SGDJB to induce diabetes remission. METHODS Fifty 11-week-old male GK rats were divided into five groups: sham-operated SG (SOSG), sham-operated SGDJB (SOSGDJB), control, SG, and SGDJB. Rats were observed for 16 weeks after surgery. The body weight, food intake, glycemic control outcomes, ghrelin, peptide YY (PYY), insulin, glucagon-like peptide 1 (GLP-1), and glucose-dependent insulinotropic peptide were measured. RESULTS The operated groups showed lower food intake since 4 weeks postoperation and significant weight loss since 6 weeks postoperation. SGDJB and SG surgeries induced a decreased fasting ghrelin level and increased levels of glucose-stimulated insulin, GLP-1, and PYY secretion at 2 and 16 weeks postoperation. Compared with the SG group, the SGDJB group showed higher glucose-stimulated GLP-1 levels. Both SGDJB and SG groups exhibited significant improvement in oral glucose tolerance and insulin tolerance compared with sham-operated and control groups, but there was no difference between the operated groups. CONCLUSIONS This nonobese diabetic rat model may be valuable in studying the effect of SGDJB on diabetic control. SGDJB shows similar improvement of glucose metabolism with SG. Our findings do not provide evidence for the foregut-mediated amelioration in glucose homeostasis.
Collapse
Affiliation(s)
- Dong Sun
- Department of General Surgery, Qilu Hospital of Shandong University, #107 Wenhua Xi Road, Jinan, 250012, Shandong, People's Republic of China
| | | | | | | | | | | |
Collapse
|
21
|
Kim HJ, Zhang XH, Park EY, Shin KH, Choi SH, Chun BG, Kim DH. Metformin decreases meal size and number and increases c-Fos expression in the nucleus tractus solitarius of obese mice. Physiol Behav 2013; 110-111:213-20. [PMID: 23391573 DOI: 10.1016/j.physbeh.2013.01.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 12/17/2012] [Accepted: 01/29/2013] [Indexed: 12/18/2022]
Abstract
Metformin is widely used to treat obese diabetics because of its beneficial effects on body weight, energy intake, and glucose regulation. However, it has not been investigated how oral metformin affects meal patterns, or whether the reduced food intake is associated with neuronal activation in the hindbrain. Accordingly, we investigated how orally administered metformin (150 or 300 mg/kg daily for 4 or 7 days) reduces body weight in obese mice on a high-fat diet by continuously measuring meal patterns, energy expenditure, and locomotor activity, and whether oral metformin (300 mg/kg daily for 3 days) increases c-Fos expression in the nucleus tractus solitarius (NTS) and area postrema. Furthermore, we determined whether oral metformin produces a conditioned taste aversion (CTA) in obese mice administered a single dose of metformin (75, 150, or 300 mg/kg, p.o.). Metformin (300 mg/kg daily for 7 days) reduced body weight and adiposity by decreasing nocturnal energy intake but did not significantly change energy expenditure or locomotor activity relative to vehicle, and it transiently decreased nocturnal meal size and reduced meal number throughout the experiments. Furthermore, metformin significantly increased c-Fos immunoreactivity within the NTS of obese mice compared to that in controls and pair-fed group, and induced a CTA at doses of 150 or 300 mg/kg. These results indicate that metformin-induced weight loss is associated with a sustained reduction in energy intake maintained by a reduction in meal size and number, and that oral administration of metformin causes visceral illness and neuronal activation in the NTS.
Collapse
|
22
|
Abstract
Peptide tyrosine-tyrosine (PYY) is implicated in eating control, but the site(s) and mechanism(s) of its action remain uncertain. We tested acute effects of intrameal hepatic portal vein (HPV) PYY(3-36) infusions on eating in adult, male rats and measured HPV and jugular vein (JV) plasma levels of PYY in response to a solid, mixed-nutrient meal. We also examined the effects of HPV PYY(3-36) infusions on JV plasma levels, flavor acceptance, and neuronal activation. Intrameal HPV PYY(3-36) infusions [1 and 3 nmol/kg body weight (BW)] selectively reduced (P < 0.05) ongoing meal size. HPV PYY levels increased (P < 0.05) during a chow (12.5 kcal) or an isocaloric high-fat meal. JV PYY levels were generally lower than HPV levels but also increased in response to the chow meal. HPV PYY(3-36) infusion (1 nmol/kg BW) caused a greater increase in JV PYY than a meal, but neither 1 nor 3 nmol/kg BW PYY(3-36) caused conditioned flavor avoidance. HPV PYY(3-36) (1 nmol/kg BW) increased the number of c-Fos-expressing cells in the nucleus tractus solitarii, the hypothalamic arcuate and paraventricular nuclei, the central area of the amygdala, and the nucleus accumbens but not in the area postrema and parabrachial nucleus. These data show that HPV infusions of PYY(3-36) inhibit eating in rats without causing avoidance, and they identify some brain areas that might be involved. Endogenous PYY may induce satiation by acting directly in the brain, but further studies should examine whether PYY(3-36) administrations that mimic the meal-induced increase in plasma PYY are sufficient to inhibit eating.
Collapse
Affiliation(s)
- Ulrike Stadlbauer
- Swiss Federal Institute of Technology Zurich, Schorenstrasse 16, 8603 Schwerzenbach, Switzerland.
| | | | | | | |
Collapse
|
23
|
Hand KV, Bruen CM, O'Halloran F, Panwar H, Calderwood D, Giblin L, Green BD. Examining acute and chronic effects of short- and long-chain fatty acids on peptide YY (PYY) gene expression, cellular storage and secretion in STC-1 cells. Eur J Nutr 2012; 52:1303-13. [PMID: 22926626 DOI: 10.1007/s00394-012-0439-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 08/08/2012] [Indexed: 12/29/2022]
Abstract
PURPOSE Peptide YY (PYY) is a gastrointestinal hormone with physiological actions regulating appetite and energy homoeostasis. The cellular mechanisms by which nutrients stimulate PYY secretion from intestinal enteroendocrine cells are still being elucidated. METHODS This study comprehensively evaluated the suitability of intestinal STC-1 cells as an in vitro model of PYY secretion. PYY concentrations (both intracellular and in culture media) with other intestinal peptides (CCK, GLP-1 and GIP) demonstrated that PYY is a prominent product of STC-1 cells. Furthermore, acute and chronic PYY responses to 15 short (SCFAs)- and long-chain (LCFAs) dietary fatty acids were measured alongside parameters for DNA synthesis, cell viability and cytotoxicity. RESULTS We found STC-1 cells to be reliable secretors of PYY constitutively releasing PYY into cell culture media (but not into non-stimulatory buffer). We demonstrate for the first time that STC-1 cells produce PYY mRNA transcripts; that STC-1 cells produce specific time- and concentration-dependent PYY secretory responses to valeric acid; that linoleic acid and conjugated linoleic acid 9,11 (CLA 9,11) are potent PYY secretagogues; and that chronic exposure of SCFAs and LCFAs can be detrimental to STC-1 cells. CONCLUSIONS Our studies demonstrate the potential usefulness of STC-1 cells as an in vitro model for investigating nutrient-stimulated PYY secretion in an acute setting. Furthermore, our discovery that CLA directly stimulates L-cells to secrete PYY indicates another possible mechanism contributing to the observed effects of dietary CLA on weight loss.
Collapse
Affiliation(s)
- Katharine V Hand
- Institute of Agri-Food and Land Use, School of Biological Sciences, Queen's University Belfast, Stranmillis Road, Belfast, UK.
| | | | | | | | | | | | | |
Collapse
|
24
|
Shi YC, Hämmerle CM, Lee ICJ, Turner N, Nguyen AD, Riepler SJ, Lin S, Sainsbury A, Herzog H, Zhang L. Adult-onset PYY overexpression in mice reduces food intake and increases lipogenic capacity. Neuropeptides 2012; 46:173-82. [PMID: 22575886 DOI: 10.1016/j.npep.2012.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 03/27/2012] [Accepted: 04/04/2012] [Indexed: 12/22/2022]
Abstract
Peptide YY (PYY) is best known for its important role in appetite regulation, but recent pharmacological studies have suggested that PYY is also involved in regulating energy balance and glucose homeostasis. However, the mechanism behind the regulation of these parameters by PYY is less clear. Here, by utilising an inducible transgenic mouse model where PYY overexpression is induced in adult animals (PYYtg) and release of mature PYY peptides is controlled by endogenous machineries, we show that elevating PYY levels leads to reduced food intake after a 24-h fast. Furthermore, PYYtg mice, although not significantly different from WT with respect to body weight, adiposity, lean mass, physical activity or energy expenditure, exhibited a significantly increased respiratory exchange ratio (RER), indicating decreased lipid oxidation and/or increased lipogenesis. Importantly, PYYtg mice showed a 25% reduction in liver protein levels of phosphorylated acetyl-CoA carboxylase (pACC) in the absence of changes in total ACC levels compared to those of WT mice. Moreover, liver protein levels of AMP-activated kinase (AMPK) in PYYtg mice were 25% lower than those of WT mice, consistent with a reduced pACC in these mice. These data suggest that elevation of PYY levels as seen after a meal can increase lipogenic capacity, which is likely a key contributor to the increased RER seen in PYYtg mice. In addition, PYYtg mice exhibited comparable insulin tolerance and oral glucose tolerance to those of WT, but showed a trend towards decreased insulin levels in response to an oral glucose challenge, indicating that PYY could improve insulin action. Taken together, these findings demonstrate that under physiological conditions, PYY reduces food intake while enhancing lipogenic capacity and insulin action, likely contributing to fuel assimilation in the postprandial state.
Collapse
Affiliation(s)
- Yan-Chuan Shi
- Neuroscience Research Program, Garvan Institute of Medical Research, 384 Victoria St., Darlinghurst, Sydney, NSW 2010, Australia
| | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Reidelberger R, Haver A, Chelikani PK, Apenteng B, Perriotte-Olson C, Anders K, Steenson S, Blevins JE. Effects of leptin replacement alone and with exendin-4 on food intake and weight regain in weight-reduced diet-induced obese rats. Am J Physiol Endocrinol Metab 2012; 302:E1576-85. [PMID: 22510712 PMCID: PMC3378160 DOI: 10.1152/ajpendo.00058.2012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Weight loss in obese humans produces a relative leptin deficiency, which is postulated to activate potent orexigenic and energy conservation mechanisms to restrict weight loss and promote weight regain. Here we determined whether leptin replacement alone or with GLP-1 receptor agonist exendin-4 attenuates weight regain or promotes greater weight loss in weight-reduced diet-induced obese (DIO) rats. Forty percent restriction in daily intake of a high-fat diet in DIO rats for 4 wk reduced body weight by 12%, body fat by 29%, and plasma leptin by 67% and normalized leptin sensitivity. When food restriction ended, body weight, body fat, and plasma leptin increased rapidly. Daily administration of leptin [3-h intraperitoneal (ip) infusions (4 nmol·kg(-1)·h(-1))] at onset and end of dark period for 3 wk did not attenuate hyperphagia and weight regain, nor did it affect mean daily meal sizes or meal numbers. Exendin-4 (50 pmol·kg(-1)·h(-1)) infusions during the same intervals prevented postrestriction hyperphagia and weight regain by normalizing meal size. Coadministration of leptin and exendin-4 did not reduce body weight more than exendin-4 alone. Instead, leptin began to attenuate the inhibitory effects of exendin-4 on food intake, meal size, and weight regain by the end of the second week of administration. Plasma leptin in rats receiving leptin was sevenfold greater than in rats receiving vehicle and 17-fold greater than in rats receiving exendin-4. Together, these results do not support the hypothesis that leptin replacement alone or with exendin-4 attenuates weight regain or promotes greater weight loss in weight-reduced DIO rats.
Collapse
Affiliation(s)
- Roger Reidelberger
- Veterans Affairs Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, 68105, USA.
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Abstract
We set out to determine the effect of peptide YY(3-36) (PYY(3-36)) on the gastric muscle tone in conscious rats by measuring intragastric pressure (IGP) during intragastric nutrient drink infusion. After an overnight fast, a chronically implanted gastric fistula was connected to a custom-made nutrient drink infusion system and a catheter to measure IGP. IGP was measured before and during the infusion of a nutrient drink (Nutridrink; 0.5 ml/min) until 10 ml was infused. Rats were treated with PYY(3-36) (0, 33, and 100 pmol·kg(-1)·min(-1)) in combination with a subcutaneous injection of the Y(2) receptor antagonists JNJ31020028 (10 mg/kg) or BIIE0246 (2 mg/kg). Experiments were also performed after subdiaphragmatic vagotomy and after pretreatment with 3 ml of nutrient drink (to mimic a fed state). IGP was compared as the average IGP during nutrient infusion, represented as means ± SE and compared using ANOVA. PYY(3-36) dose dependently increased the IGP during nutrient infusion (4.7 ± 0.3, 5.7 ± 0.5 and 7.3 ± 0.7 mmHg; P < 0.01) while JNJ31020028 and BIIE0246 could block this increase [4.4 ± 0.5 (P < 0.001) and 4.8 ± 0.4 (P < 0.05) mmHg, respectively]. Also in vagotomized rats, PYY(3-36) was able to significantly increase the IGP during, an effect attenuated by JNJ31020028. BIIE0246 and JNJ31020028 were not able to decrease the IGP when no PYY(3-36) was administered. PYY(3-36) increased gastric tone through an Y(2) receptor-mediated mechanism that does not involve the vagus nerve. Y(2) receptor antagonists were not able to decrease gastric tone without exogenous administration of PYY(3-36), indicating that Y(2) receptors do not play a crucial role in the determination of gastric tone in physiological conditions.
Collapse
Affiliation(s)
- P Janssen
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | | | | | | |
Collapse
|
27
|
Mönkäre J, Hakala RA, Kovalainen M, Korhonen H, Herzig KH, Seppälä JV, Järvinen K. Photocrosslinked poly(ester anhydride)s for peptide delivery: Effect of oligomer hydrophobicity on PYY3-36 delivery. Eur J Pharm Biopharm 2012; 80:33-8. [DOI: 10.1016/j.ejpb.2011.09.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 08/23/2011] [Accepted: 09/15/2011] [Indexed: 11/30/2022]
|
28
|
Abstract
The neuropeptide Y system has proven to be one of the most important regulators of feeding behaviour and energy homeostasis, thus presenting great potential as a therapeutic target for the treatment of disorders such as obesity and at the other extreme, anorexia. Due to the initial lack of pharmacological tools that are active in vivo, functions of the different Y receptors have been mainly studied in knockout and transgenic mouse models. However, over recent years various Y receptor selective peptidic and non-peptidic agonists and antagonists have been developed and tested. Their therapeutic potential in relation to treating obesity and other disorders of energy homeostasis is discussed in this review.
Collapse
Affiliation(s)
- Ernie Yulyaningsih
- Neuroscience Research Program, Garvan Institute of Medical Research, St Vincent's Hospital, Darlinghurst, Sydney, NSW, Australia
| | | | | | | |
Collapse
|
29
|
Kovalainen M, Mönkäre J, Mäkilä E, Salonen J, Lehto V, Herzig K, Järvinen K. Mesoporous Silicon (PSi) for Sustained Peptide Delivery: Effect of PSi Microparticle Surface Chemistry on Peptide YY3-36 Release. Pharm Res 2012; 29:837-46. [DOI: 10.1007/s11095-011-0611-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 10/17/2011] [Indexed: 11/27/2022]
|
30
|
Abstract
Here we review the emerging neurobiological understanding of the role of the brain's reward system in the regulation of body weight in health and in disease. Common obesity is characterized by the over-consumption of palatable/rewarding foods, reflecting an imbalance in the relative importance of hedonic versus homeostatic signals. The popular 'incentive salience theory' of food reward recognises not only a hedonic/pleasure component ('liking') but also an incentive motivation component ('wanting' or 'reward-seeking'). Central to the neurobiology of the reward mechanism is the mesoaccumbal dopamine system that confers incentive motivation not only for natural rewards such as food but also by artificial rewards (eg. addictive drugs). Indeed, this mesoaccumbal dopamine system receives and integrates information about the incentive (rewarding) value of foods with information about metabolic status. Problematic over-eating likely reflects a changing balance in the control exerted by hypothalamic versus reward circuits and/or it could reflect an allostatic shift in the hedonic set point for food reward. Certainly, for obesity to prevail, metabolic satiety signals such as leptin and insulin fail to regain control of appetitive brain networks, including those involved in food reward. On the other hand, metabolic control could reflect increased signalling by the stomach-derived orexigenic hormone, ghrelin. We have shown that ghrelin activates the mesoaccumbal dopamine system and that central ghrelin signalling is required for reward from both chemical drugs (eg alcohol) and also from palatable food. Future therapies for problematic over-eating and obesity may include drugs that interfere with incentive motivation, such as ghrelin antagonists.
Collapse
Affiliation(s)
- Emil Egecioglu
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, PO Box 434, SE-405 30 Gothenburg, Sweden
| | - Karolina P. Skibicka
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, PO Box 434, SE-405 30 Gothenburg, Sweden
| | - Caroline Hansson
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, PO Box 434, SE-405 30 Gothenburg, Sweden
| | - Mayte Alvarez-Crespo
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, PO Box 434, SE-405 30 Gothenburg, Sweden
| | - P. Anders Friberg
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, PO Box 434, SE-405 30 Gothenburg, Sweden
| | - Elisabet Jerlhag
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, PO Box 434, SE-405 30 Gothenburg, Sweden
| | - Jörgen A. Engel
- Department of Pharmacology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, PO Box 434, SE-405 30 Gothenburg, Sweden
| | - Suzanne L. Dickson
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, PO Box 434, SE-405 30 Gothenburg, Sweden
| |
Collapse
|
31
|
Gass M, Beglinger C, Peterli R. Metabolic surgery-principles and current concepts. Langenbecks Arch Surg 2011; 396:949-72. [PMID: 21870176 DOI: 10.1007/s00423-011-0834-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 08/01/2011] [Indexed: 12/19/2022]
Abstract
INTRODUCTION In the almost six decades of bariatric surgery, a variety of surgical approaches to treating morbid obesity have been developed. HISTORY AND EVOLUTION Rather than prior techniques being continually superseded by new ones, a broad choice of surgical solutions based on restrictive, malabsorptive, humoral effects, or combinations thereof, is now available. In fact, in recent years, the advent of surgically modifying human metabolism promises new approaches to ameliorate traditionally medically treated metabolic entities, i.e., diabetes, even in the non-obese. The understanding of the various metabolic effects have led to a paradigm shift from bariatric surgery as a solely weight-reducing procedure to metabolic surgery affecting whole body metabolism. CONCLUSION The bariatric surgeon now faces the challenge and opportunity of selecting the most suitable technique for each individual case. To assist in such decision-making, this review, Metabolic surgery-principles and current concepts, is presented, tracing the historical development; describing the various surgical techniques; elucidating the mechanisms by which glycemic control can be achieved that involve favorable changes in insulin secretion and insulin sensitivity, gut hormones, adipokines, energy expenditure, appetite, and preference for low glycemic index foods; as well as exploring the fascinating future potential of this new interdisciplinary field.
Collapse
|
32
|
Zhang L, Bijker MS, Herzog H. The neuropeptide Y system: Pathophysiological and therapeutic implications in obesity and cancer. Pharmacol Ther 2011; 131:91-113. [DOI: 10.1016/j.pharmthera.2011.03.011] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2011] [Accepted: 03/07/2011] [Indexed: 12/28/2022]
|
33
|
Abstract
AIMS Peptide YY (PYY) is an endogenous anorectic gut-secreted peptide that has been shown to suppress appetite in animals and humans, when given by injection. This study tested if needle-free pulmonary delivery of PYY enables food intake suppression and reduced body weight gain in rats. The PYY pharmacokinetics and effects on brain neuropeptide levels were also examined. METHODS Rats received single or once-daily 7-day pulmonary administration of saline or PYYs. Food intake and body weight gain were monitored to study the effects of different doses (0.08-0.90 mg/kg) of PYY3-36, PYY1-36 and PYY13-36. Plasma PYY pharmacokinetics were determined via enzyme-linked immunosorbent assay. Changes in orexigenic neuropeptide Y (NPY) and c-Fos protein levels in the hypothalamus arcuate nucleus (ARC) were measured by immunofluorescence microscopy. RESULTS PYY3-36 caused dose-dependent and 4- to 6-h food intake suppression following pulmonary delivery. At 0.80 mg/kg, the effect was significant with 35.1 ± 5.7 and 19.7 ± 4.2% suppression at 4 and 6 h, respectively. Repeated administration for 7 days reduced cumulative body weight gain by 39.4 ± 11.0%. PYY1-36, but not PYY13-36, was equipotent to PYY3-36 in food intake suppression. The plasma PYY concentration reached its peak at 10 min following pulmonary delivery with 12-14% of bioavailability. Increased c-Fos and reduced NPY expressions were observed in the hypothalamus ARC, consistent with the magnitude of food intake suppression by each of the PYYs. CONCLUSIONS Pulmonary delivery of PYY enabled significant 4- to 6-h food intake suppression via 12-14% of lung absorption and hypothalamic ARC interaction, leading to reduced body weight gain in rats.
Collapse
Affiliation(s)
- P P Nadkarni
- Department of Pharmaceutics, School of Pharmacy, Virginia Commonwealth University, Richmond, USA
| | | | | |
Collapse
|
34
|
Abstract
Peptidergic and neural signals arising from the presence of food in the gastrointestinal track provide feedback signals to the brain about the nature and quantity of consumed nutrients. Peptide secreting cells are differentially distributed along the gastrointestinal tract. How ingested nutrients activate or inhibit peptide secretion is complex and depends upon local, hormonal and neural mechanisms. The mode of action of the various peptides is equally complex involving endocrine, paracrine and neurocrine signaling. The success of bariatric surgical approaches to obesity treatment is secondary to alterations in gastrointestinal feedback signaling and roles of increased secretion of lower gut peptides such as peptide YY (PYY) and glucagon like peptide 1 (GLP-1) in mediating the superior effects of Roux-en-Y gastric bypass (RYGB) surgery are becoming evident. Direct nutrient delivery to jejunal sites that models the site of gastric-jejunal anastamosis in RYGB is especially effective at inhibiting food intake. Such infusions also stimulate the release of lower gut peptides suggesting a role for increased gut peptide signaling in sustaining such feeding inhibitions. Thus, gut peptides are clear targets for future obesity therapeutic developments.
Collapse
Affiliation(s)
- Timothy H Moran
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Ross 618, 720 Rutland Ave., Baltimore, MD 21205, United States.
| | | |
Collapse
|
35
|
Ford HE, Peters V, Martin NM, Sleeth ML, Ghatei MA, Frost GS, Bloom SR. Effects of oral ingestion of sucralose on gut hormone response and appetite in healthy normal-weight subjects. Eur J Clin Nutr 2011; 65:508-13. [DOI: 10.1038/ejcn.2010.291] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
36
|
Chelikani PK, Shah IH, Taqi E, Sigalet DL, Koopmans HH. Comparison of the effects of Roux-en-Y gastric bypass and ileal transposition surgeries on food intake, body weight, and circulating peptide YY concentrations in rats. Obes Surg 2011; 20:1281-8. [PMID: 20386999 DOI: 10.1007/s11695-010-0139-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Roux-en-Y gastric bypass (RYGB) surgery is one of the most effective treatments for obesity producing long-term weight loss. The anorexia and weight loss from RYGB could be due to gastric restriction, malabsorption, enhanced lower gut stimulation, increased energy expenditure, and/or other metabolic adaptations. In ileal transposition (IT) surgery, a segment of the ileum is transposed to the upper jejunum with no gastric restriction or malabsorption. Our objective is to compare the effects of RYGB and IT surgeries on food intake, body weight, and plasma concentrations of the anorexigenic lower gut hormone Peptide YY (PYY) in rats. METHODS Adult male Sprague-Dawley rats were subjected to either RYGB (n = 9), IT (n = 9) or sham surgeries (n = 16). A subset of sham animals were either pair-fed to RYGB (n = 9) or ad lib fed (n = 7) on a highly palatable mixed nutrient liquid food (Ensure). Food intake, body weight and plasma PYY concentrations were measured. RESULTS The data demonstrate that (1) RYGB produces a sustained reduction in food intake and weight gain, (2) the anorexic effects of IT are relatively transient lasting for 5 weeks, (3) the reduction in weight gain resulting from IT is similar to that of animals pair-fed to RYGB, and (4) RYGB and IT surgeries are associated with elevated postprandial plasma PYY concentrations. CONCLUSIONS We demonstrate in our rat models that RYGB surgery produces a greater reduction in food intake and weight gain than IT surgery, and that both surgeries are associated with enhanced plasma concentrations of Peptide YY.
Collapse
Affiliation(s)
- Prasanth K Chelikani
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, 3330 University Drive NW, Calgary, Alberta, T2N 4N1, Canada.
| | | | | | | | | |
Collapse
|
37
|
Reidelberger RD, Haver AC, Apenteng BA, Anders KL, Steenson SM. Effects of exendin-4 alone and with peptide YY(3-36) on food intake and body weight in diet-induced obese rats. Obesity (Silver Spring) 2011; 19:121-7. [PMID: 20559304 DOI: 10.1038/oby.2010.136] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Significant weight loss following Roux-en-Y gastric bypass surgery (RYGB) in obese humans correlates with enhanced secretion of anorexigenic gut hormones glucagon-like peptide-1 (GLP-1) and peptide YY(3-36) (PYY(3-36)). Our aim here was to identify a dosing strategy for intraperitoneal (IP) infusion of GLP-1 homologue exendin-4 alone and with PYY(3-36) that produces a sustained reduction in daily food intake and body weight in diet-induced obese (DIO) rats. We tested 12 exendin-4 strategies over 10 weeks. Exendin-4 infused during the first and last 3 h of the dark period at 15-20 pmol/h (0.15 nmol/kg/day) produced a sustained 24 ± 1% reduction in daily food intake for 17 days, and decreased body weight by 7%. In a separate group of DIO rats, none of seven dosing strategies combining exendin-4 and PYY(3-36) produced a similar reduction in daily food intake for >10 days. The subsequent decline in efficacies of exendin-4 alone and with PYY(3-36) on food intake and body weight in each experiment suggested possible receptor downregulation and tolerance to treatments. However, when treatments were discontinued for 1 day following losses in efficacies, daily food intake significantly increased. Together, these results demonstrate that (i) intermittent IP infusion of a low dose of exendin-4 can produce a relatively prolonged reduction in daily food intake and body weight in DIO rats, (ii) co-infusion of exendin-4 and PYY(3-36) does not further prolong this response, and (iii) activation of an orexigenic mechanism gradually occurs to counteract the inhibitory effects of exendin-4 alone and with PYY(3-36) on food intake and body weight.
Collapse
Affiliation(s)
- Roger D Reidelberger
- Department of Veterans Affairs, Nebraska Western Iowa Health Care System, Omaha, Nebraska, USA.
| | | | | | | | | |
Collapse
|
38
|
Abstract
Our knowledge of the complex mechanisms underlying energy homeostasis has expanded enormously in recent years. Food intake and body weight are tightly regulated by the hypothalamus, brainstem and reward circuits, on the basis both of cognitive inputs and of diverse humoral and neuronal signals of nutritional status. Several gut hormones, including cholecystokinin, glucagon-like peptide-1, peptide YY, oxyntomodulin, amylin, pancreatic polypeptide and ghrelin, have been shown to play an important role in regulating short-term food intake. These hormones therefore represent potential targets in the development of novel anti-obesity drugs. This review focuses on the role of gut hormones in short- and long-term regulation of food intake, and on the current state of development of gut hormone-based obesity therapies.
Collapse
Affiliation(s)
- Benjamin C T Field
- Department of Investigative Medicine, Imperial College London, Hammersmith Hospital Campus, London, UK
| | | | | |
Collapse
|
39
|
Zheng H, Lenard NR, Shin AC, Berthoud HR. Appetite control and energy balance regulation in the modern world: reward-driven brain overrides repletion signals. Int J Obes (Lond) 2010; 33 Suppl 2:S8-13. [PMID: 19528982 DOI: 10.1038/ijo.2009.65] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Powerful biological mechanisms evolved to defend adequate nutrient supply and optimal levels of body weight/adiposity. Low levels of leptin indicating food deprivation and depleted fat stores have been identified as the strongest signals to induce adaptive biological actions such as increased energy intake and reduced energy expenditure. In concert with other signals from the gut and metabolically active tissues, low leptin levels trigger powerful activation of multiple peripheral and brain systems to restore energy balance. It is not just neurons in the arcuate nucleus, but many other brain systems involved in finding potential food sources, smelling and tasting food, and learning to maximize rewarding effects of foods, that are affected by low leptin. Food restriction and fat depletion thus lead to a 'hungry' brain, preoccupied with food. By contrast, because of less (adaptive thrifty fuel efficiency) or lost (lack of predators) evolutionary pressure, the upper limits of body weight/adiposity are not as strongly defended by high levels of leptin and other signals. The modern environment is characterized by the increased availability of large amounts of energy-dense foods and increased presence of powerful food cues, together with minimal physical procurement costs and a sedentary lifestyle. Much of these environmental influences affect cortico-limbic brain areas concerned with learning and memory, reward, mood and emotion. Common obesity results when individual predisposition to deal with a restrictive environment, as engraved by genetics, epigenetics and/or early life experience, is confronted with an environment of plenty. Therefore, increased adiposity in prone individuals should be seen as a normal physiological response to a changed environment, not in the pathology of the regulatory system. The first line of defense should ideally lie in modifications to the environment and lifestyle. However, as such modifications will be slow and incomplete, it is equally important to gain better insight into how the brain deals with environmental stimuli and to develop behavioral strategies to better cope with them. Clearly, alternative therapeutic strategies such as drugs and bariatric surgery should also be considered to prevent or treat this debilitating disease. It will be crucial to understand the functional crosstalk between neural systems responding to metabolic and environmental stimuli, i.e. crosstalk between hypothalamic and cortico-limbic circuitry.
Collapse
Affiliation(s)
- H Zheng
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808, USA
| | | | | | | |
Collapse
|
40
|
Keire DA, Whitelegge JP, Souda P, Faull KF, Bassilian S, Reidelberger RD, Haver AC, Reeve JR Jr. PYY(1-36) is the major form of PYY in rat distal small intestine: quantification using high-resolution mass spectrometry. ACTA ACUST UNITED AC 2010; 165:151-7. [PMID: 20615437 DOI: 10.1016/j.regpep.2010.06.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 05/26/2010] [Accepted: 06/28/2010] [Indexed: 11/22/2022]
Abstract
We measured molecular forms of PYY in the distal half of rat small intestine using a new method for tissue extraction, three sequential reverse phase chromatography steps, and PYY radioimmunoassay and mass spectrometry to measure their levels. The extraction method called RAPID, developed to minimize artifactual degradation of PYY during tissue extraction and sample preparation, uses Reduced temperature, Acidified buffer, Peptidase inhibitors, Isotopically enriched mass spectrometry standards, and Dilution to inhibit and monitor endogenous peptide degradation during tissue processing. Synthetic peptides [PYY(1-36)-NH(2), PYY(3-36)-NH(2), PYY(1-36)-Gly-OH, and PYY(3-36)-Gly-OH] selectively enriched with (13)C(3)-alanine were added as internal standards to the extraction buffer. By collecting mass spectra rather than multiple-reaction-monitoring (MRM) profiles, we simultaneously screen for any PYY forms that were present in the immunoreactive fractions. PYY(1-36)-NH(2), PYY(3-36)-NH(2), PYY(1-36)-Gly-OH, and PYY(3-36)-Gly-OH were identified and quantified at 64.3±4.5, 6.1±0.9, 0.9±0.1, and <0.3pmol/g of tissue, respectively (n=3). Thus, we found that in rat distal small intestine proPYY is processed to PYY(1-36)-NH(2) with little conversion to PYY(3-36)-NH(2). These data suggest that production of PYY(3-36)-NH(2) (a form with greater potency than PYY(1-36)-NH(2) for inhibition of feeding and gastric emptying) occurs after the peptide leaves its cell of synthesis by enzymatic action in the circulation.
Collapse
|
41
|
Akerberg H, Meyerson B, Sallander M, Lagerstedt AS, Hedhammar A, Larhammar D. Peripheral administration of pancreatic polypeptide inhibits components of food-intake behavior in dogs. Peptides 2010; 31:1055-61. [PMID: 20338207 DOI: 10.1016/j.peptides.2010.03.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2010] [Revised: 03/15/2010] [Accepted: 03/15/2010] [Indexed: 11/25/2022]
Abstract
Pancreatic polypeptide (PP) belongs to the neuropeptide Y (NPY) family of peptides and is released from pancreatic F cells postprandially. PP functions as a peptide hormone and has been associated with decreased food intake in humans and rodents. Our study describes the effects of PP on feeding behavior in dogs, whose mammalian order (Carnivora) is more distantly related to primates and rodents than these are to each other. Furthermore, obesity is becoming more prevalent in dogs which makes knowledge about their appetite regulation highly relevant. Repeated peripheral administration of physiological doses of PP (three injections of 30 pmol/kg each that were administered within 30 min) to six male beagle dogs prolonged the median time spent eating three servings of food by 19% but resulted in no reduction of food intake. In addition, PP decreased the duration of food-seeking behavior after the first serving by 71%. Thus, a physiological dose of PP seems to decrease both the appetitive and the consummatory drive in dogs.
Collapse
Affiliation(s)
- Helena Akerberg
- Department of Neuroscience, Uppsala University, Box 593, SE-75124 Uppsala, Sweden.
| | | | | | | | | | | |
Collapse
|
42
|
Lin S, Shi YC, Yulyaningsih E, Aljanova A, Zhang L, Macia L, Nguyen AD, Lin EJD, During MJ, Herzog H, Sainsbury A. Critical role of arcuate Y4 receptors and the melanocortin system in pancreatic polypeptide-induced reduction in food intake in mice. PLoS One 2009; 4:e8488. [PMID: 20041129 PMCID: PMC2796177 DOI: 10.1371/journal.pone.0008488] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Accepted: 11/27/2009] [Indexed: 11/25/2022] Open
Abstract
Background Pancreatic polypeptide (PP) is a potent anti-obesity agent known to inhibit food intake in the absence of nausea, but the mechanism behind this process is unknown. Methodology/Principal Findings Here we demonstrate that in response to i.p. injection of PP in wild type but not in Y4 receptor knockout mice, immunostaining for the neuronal activation marker c-Fos is induced specifically in neurons of the nucleus tractus solitarius and the area postrema in the brainstem, notably in cells also showing immunostaining for tyrosine hydroxylase. Importantly, strong c-Fos activation is also detected in the arcuate nucleus of the hypothalamus (ARC), particularly in neurons that co-express alpha melanocyte stimulating hormone (α-MSH), the anorexigenic product of the proopiomelanocortin (POMC) gene. Interestingly, other hypothalamic regions such as the paraventricular nucleus, the ventromedial nucleus and the lateral hypothalamic area also show c-Fos induction after PP injection. In addition to c-Fos activation, PP injection up-regulates POMC mRNA expression in the ARC as detected by in situ hybridization. These effects are a direct consequence of local Y4 signaling, since hypothalamus-specific conditional Y4 receptor knockout abolishes PP-induced ARC c-Fos activation and blocks the PP-induced increase in POMC mRNA expression. Additionally, the hypophagic effect of i.p. PP seen in wild type mice is completely absent in melanocortin 4 receptor knockout mice. Conclusions/Significance Taken together, these findings show that PP reduces food intake predominantly via stimulation of the anorexigenic α-MSH signaling pathway, and that this effect is mediated by direct action on local Y4 receptors within the ARC, highlighting a potential novel avenue for the treatment of obesity.
Collapse
Affiliation(s)
- Shu Lin
- Neuroscience Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
| | - Yan-Chuan Shi
- Neuroscience Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
| | - Ernie Yulyaningsih
- Neuroscience Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
| | - Aygul Aljanova
- Neuroscience Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
| | - Lei Zhang
- Neuroscience Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
| | - Laurence Macia
- Neuroscience Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
| | - Amy D. Nguyen
- Neuroscience Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
| | - En-Ju Deborah Lin
- Cancer Genetics and Neuroscience Program, Department of Molecular Virology, Immunology and Medical Genetics, and the Comprehensive Cancer Center, Ohio State University, Columbus, Ohio, United States of America
| | - Matthew J. During
- Cancer Genetics and Neuroscience Program, Department of Molecular Virology, Immunology and Medical Genetics, and the Comprehensive Cancer Center, Ohio State University, Columbus, Ohio, United States of America
| | - Herbert Herzog
- Neuroscience Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
- Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
- * E-mail:
| | - Amanda Sainsbury
- Neuroscience Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
- School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| |
Collapse
|
43
|
Zhang L, Macia L, Turner N, Enriquez RF, Riepler SJ, Nguyen AD, Lin S, Lee NJ, Shi YC, Yulyaningsih E, Slack K, Baldock PA, Herzog H, Sainsbury A. Peripheral neuropeptide Y Y1 receptors regulate lipid oxidation and fat accretion. Int J Obes (Lond) 2009; 34:357-73. [PMID: 19918245 DOI: 10.1038/ijo.2009.232] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Neuropeptide Y and its Y receptors are important players in the regulation of energy homeostasis. However, while their functions in feeding regulation are well recognized, functions in other critical aspects of energy homeostasis are largely unknown. To investigate the function of Y1 receptors in the regulation of energy homeostasis, we examined energy expenditure, physical activity, body composition, oxidative fuel selection and mitochondrial oxidative capacity in germline Y1(-/-) mice as well as in a conditional Y1-receptor-knockdown model in which Y1 receptors were knocked down in peripheral tissues of adult mice. RESULTS Germline Y1(-/-) mice of both genders not only exhibit a decreased respiratory exchange ratio, indicative of increased lipid oxidation, but interestingly also develop late-onset obesity. However, the increased lipid oxidation is a primary effect of Y1 deletion rather than secondary to increased adiposity, as young Y1(-/-) mice are lean and show the same effect. The mechanism behind this is likely because of increased liver and muscle protein levels of carnitine palmitoyltransferase-1 (CPT-1) and maximal activity of key enzymes involved in beta-oxidation; beta-hydroxyacyl CoA dehydrogenase (betaHAD) and medium-chain acyl-CoA dehydrogenase (MCAD), leading to increased mitochondrial capacity for fatty acid transport and oxidation. These effects are controlled by peripheral Y1-receptor signalling, as adult-onset conditional Y1 knockdown in peripheral tissues also leads to increased lipid oxidation, liver CPT-1 levels and betaHAD activity. Importantly, these mice are resistant to diet-induced obesity. CONCLUSIONS This work shows the primary function of peripheral Y1 receptors in the regulation of oxidative fuel selection and adiposity, opening up new avenues for anti-obesity treatments by targeting energy utilization in peripheral tissues rather than suppressing appetite by central effects.
Collapse
Affiliation(s)
- L Zhang
- Neuroscience Research Program, Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales, Australia
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Shin AC, Zheng H, Berthoud HR. An expanded view of energy homeostasis: neural integration of metabolic, cognitive, and emotional drives to eat. Physiol Behav 2009; 97:572-80. [PMID: 19419661 PMCID: PMC2765252 DOI: 10.1016/j.physbeh.2009.02.010] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 02/03/2009] [Accepted: 02/05/2009] [Indexed: 01/01/2023]
Abstract
The traditional view of neural regulation of body energy homeostasis focuses on internal feedback signals integrated in the hypothalamus and brainstem and in turn leading to balanced activation of behavioral, autonomic, and endocrine effector pathways leading to changes in food intake and energy expenditure. Recent observations have demonstrated that many of these internal signals encoding energy status have much wider effects on the brain, particularly sensory and cortico-limbic systems that process information from the outside world by detecting and interpreting food cues, forming, storing, and recalling representations of experience with food, and assigning hedonic and motivational value to conditioned and unconditioned food stimuli. Thus, part of the metabolic feedback from the internal milieu regulates food intake and energy balance by acting on extrahypothalamic structures, leading to an expanded view of neural control of energy homeostasis taking into account the need to adapt to changing conditions in the environment. The realization that metabolic signals act directly on these non-traditional targets of body energy homeostasis brings opportunities for novel drug targets for the fight against obesity and eating disorders.
Collapse
Affiliation(s)
- Andrew C Shin
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | | | | |
Collapse
|
45
|
Abstract
A changing environment and lifestyle on the background of evolutionary engraved and perinatally imprinted physiological response patterns is the foremost explanation for the current obesity epidemic. However, it is not clear what the mechanisms are by which the modern environment overrides the physiological controls of appetite and homeostatic body-weight regulation. Food intake and energy expenditure are controlled by complex, redundant, and distributed neural systems involving thousands of genes and reflecting the fundamental biological importance of adequate nutrient supply and energy balance. There has been much progress in identifying the important role of hypothalamus and caudal brainstem in the various hormonal and neural mechanisms by which the brain informs itself about availability of ingested and stored nutrients and, in turn, generates behavioral, autonomic, and endocrine output. Some of the genes involved in this "homeostatic" regulator are crucial for energy balance as manifested in the well-known monogenic obesity models. However, it can be clearly demonstrated that much larger portions of the nervous system of animals and humans, including the cortex, basal ganglia, and the limbic system, are concerned with the procurement of food as a basic and evolutionarily conserved survival mechanism to defend the lower limits of adiposity. By forming representations and reward expectancies through processes of learning and memory, these systems evolved to engage powerful emotions for guaranteed supply with, and ingestion of, beneficial foods from a sparse and often hostile environment. They are now simply overwhelmed with an abundance of food and food cues no longer contested by predators and interrupted by famines. The anatomy, chemistry, and functions of these elaborate neural systems and their interactions with the "homeostatic" regulator in the hypothalamus are poorly understood, and many of the genes involved are either unknown or not well characterized. This is regrettable because these systems are directly and primarily involved in the interactions of the modern environment and lifestyle with the human body. They are no less "physiological" than metabolic-regulatory mechanisms that have attracted most of the research during the past 15 years.
Collapse
Affiliation(s)
- Natalie R. Lenard
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Hans-Rudolf Berthoud
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| |
Collapse
|
46
|
Abstract
OBJECTIVE The beneficial effects of metformin in patients with type 2 diabetes mellitus (T2DM) and polycystic ovarian syndrome (PCOS) are thought to be in part due to weight reduction. However, the mechanisms by which metformin causes weight loss are unclear. We sought to determine whether circulating levels of the anorectic gut hormone peptide tyrosine tyrosine (PYY) show any correlation with metformin-induced weight loss. DESIGN AND PATIENTS We examined the acute effects of orally administrated metformin on fasting PYY levels in eight healthy normal-weight female subjects. Subsequently, we evaluated the effects of 6 months metformin treatment on fasting PYY levels and anthropometric measurements in 20 women with PCOS. RESULTS In normal-weight females 10 days' metformin treatment increased fasting PYY levels (P < 0.01). Similarly, in PCOS subjects metformin treatment increased fasting PYY concentrations (P < 0.05). In both groups a marked variation in PYY increase in response to metformin was observed. Long-term metformin treatment was associated with improvements in weight (P < 0.05), BMI (P < 0.05), fasting glucose (P < 0.05) and menstrual frequency (P < 0.01). Interestingly, change in PYY levels were correlated with change in waist circumference (r = 0.55, P < 0.05). CONCLUSIONS Acute and chronic oral metformin administration increase fasting PYY levels and may contribute to metformin's weight loss effect. Further studies are now required to clarify whether changes in circulating PYY levels in response to metformin treatment can be used to predict which patients will subsequently lose weight long-term and gain cycle restoration.
Collapse
Affiliation(s)
- Tasoula Tsilchorozidou
- Department of Endocrinology, Diabetes and Metabolism, AHEPA University Hospital, Thessaloniki, Greece
| | | | | |
Collapse
|
47
|
Abstract
The worldwide increase in obesity prevalence is a result of positive energy balance, with energy intake exceeding expenditure. The eating behavior in obesity ranges from mild passive overconsumption to excessive overeating with loss of control observed in binge eating disorder (BED). The signaling systems that underlie appetite control in BED are complex and, at this point, not well understood. The present review highlights the current knowledge of key components of the gut peptide system and examines evidence of defects in signaling that differentiate obese binge eaters from obese non-binge eaters. The signaling network underlying hunger, satiety, and metabolic status includes leptin and insulin from energy stores and cholecystokinin, glucagon-like peptide-1, peptide YY(3-36), and ghrelin from the gastrointestinal tract. Of the many gastrointestinal peptides, ghrelin is the only established appetite-stimulating one, whereas cholecystokinin, glucagon-like peptide-1, and peptide YY(3-36) promote satiety. Adipose tissue provides hormonal signals via leptin and insulin to the brain about energy stores and likely from adiponectin and resistin. Binge eating has been related to a dysfunction in the ghrelin signaling system. Moreover, the larger gastric capacity observed in BED may further reduce satiety signals and contribute to overeating.
Collapse
Affiliation(s)
- Allan Geliebter
- NY Obesity Research Center, St Luke's-Roosevelt Hospital, Columbia University College of Physicians and Surgeons, New York, New York
| | - Christopher N Ochner
- NY Obesity Research Center, St Luke's-Roosevelt Hospital, Columbia University College of Physicians and Surgeons, New York, New York
| | - Roni Aviram-Friedman
- NY Obesity Research Center, St Luke's-Roosevelt Hospital, Columbia University College of Physicians and Surgeons, New York, New York
| |
Collapse
|
48
|
Reidelberger RD, Haver AC, Chelikani PK, Buescher JL. Effects of different intermittent peptide YY (3-36) dosing strategies on food intake, body weight, and adiposity in diet-induced obese rats. Am J Physiol Regul Integr Comp Physiol 2008; 295:R449-58. [PMID: 18550871 DOI: 10.1152/ajpregu.00040.2008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Chronic administration of anorexigenic substances to experimental animals by injections or continuous infusion typically produces either no effect or a transient reduction in food intake and body weight. Our aim here was to identify an intermittent dosing strategy for intraperitoneal infusion of peptide YY(3-36) [PYY(3-36)] that produces a sustained reduction in daily food intake and adiposity in diet-induced obese rats. Rats (665+/-10 g body wt, 166+/-7 g body fat) with intraperitoneal catheters tethered to infusion swivels had free access to a high-fat diet. Vehicle-treated rats (n=23) had relatively stable food intake, body weight, and adiposity during the 9-wk test period. None of 15 PYY(3-36) dosing regimens administered in succession to a second group of rats (n=22) produced a sustained 15-25% reduction in daily food intake for >5 days, although body weight and adiposity were reduced across the 9-wk period by 12% (594+/-15 vs. 672+/-15 g) and 43% (96+/-7 vs. 169+/-9 g), respectively. The declining inhibitory effect of PYY(3-36) on daily food intake when the interinfusion interval was >or=3 h appeared to be due in part to an increase in food intake between infusions. The declining inhibitory effect of PYY(3-36) on daily food intake when the interinfusion interval was <3 h suggested possible receptor downregulation and tolerance to frequent PYY(3-36) administration; however, food intake significantly increased when PYY(3-36) treatments were discontinued for 1 day following apparent loss in treatment efficacies. Together, these results demonstrate the development of a potent homeostatic response to increase food intake when PYY(3-36) reduces food intake and energy reserves in diet-induced obese rats.
Collapse
Affiliation(s)
- Roger D Reidelberger
- Department of Veterans Affairs, Nebraska Western Iowa Health Care System, Omaha, NE 68105, USA.
| | | | | | | |
Collapse
|
49
|
Abstract
Studying communication between the gut and the brain is as relevant and exciting as it has been since Pavlov's discoveries a century ago. Although the efferent limb of this communication has witnessed significant advances, it is the afferent, or sensory, limb that has recently made for exciting news. It is now clear that signals from the gut are crucial for the control of appetite and the regulation of energy balance, glucose homeostasis, and more. Ghrelin, discovered just a few years ago, is the first gut hormone that increases appetite, and it may be involved in eating disorders. The stable analogue of glucagon-like peptide-1 has rapidly advanced to one of the most promising treatment options for type-2 diabetes. Changes in the signalling patterns of these and other gut hormones best explain the remarkable capacity of gastric bypass surgery to lower food intake and excess body weight. Given the enormous societal implications of the obesity epidemic, these are no small feats. Together with the older gut hormone cholecystokinin and abundant vagal mechanosensors, the gut continuously sends information to the brain regarding the quality and quantity of ingested nutrients, not only important for satiation and meal termination, but also for the appetitive phase of ingestive behaviour and the patterning of meals within given environmental constraints. By acting not only on brainstem and hypothalamus, this stream of sensory information from the gut to the brain is in a position to generate a feeling of satisfaction and happiness as observed after a satiating meal and exploited in vagal afferent stimulation for depression.
Collapse
Affiliation(s)
- H-R Berthoud
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808, USA.
| |
Collapse
|
50
|
Abstract
Food intake and energy expenditure are controlled by complex, redundant, and distributed neural systems that reflect the fundamental biological importance of adequate nutrient supply and energy balance. Much progress has been made in identifying the various hormonal and neural mechanisms by which the brain informs itself about availability of ingested and stored nutrients and, in turn, generates behavioral, autonomic, and endocrine output. While hypothalamus and caudal brainstem play crucial roles in this homeostatic function, areas in the cortex and limbic system are important for processing information regarding prior experience with food, reward, and emotion, as well as social and environmental context. Most vertebrates can store a considerable amount of energy as fat for later use, and this ability has now become one of the major health risks for many human populations. The predisposition to develop obesity can theoretically result from any pathological malfunction or lack of adaptation to changing environments of this highly complex system.
Collapse
Affiliation(s)
- Hans-Rudolf Berthoud
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA.
| | | |
Collapse
|