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Rafiei N, Mitchell CS, Tedesco CR, Chen J, Choi EA, Roughley S, Jean-Richard-Dit-Bressel P, Kumar NN, McNally GP, Herzog H, Begg DP. Chemogenetic activation ofarcuate nucleus NPY and NPY/AgRP neurons increases feeding behaviour in mice. Neuropeptides 2024; 107:102454. [PMID: 38970907 DOI: 10.1016/j.npep.2024.102454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 07/01/2024] [Accepted: 07/02/2024] [Indexed: 07/08/2024]
Abstract
Neuropeptide Y (NPY) plays a crucial role in controlling energy homeostasis and feeding behaviour. The role of NPY neurons located in the arcuate nucleus of the hypothalamus (Arc) in responding to homeostatic signals has been the focus of much investigation, but most studies have used AgRP promoter-driven models, which do not fully encompass Arc NPY neurons. To directly investigate NPY-expressing versus AgRP-expressing Arc neurons function, we utilised chemogenetic techniques in NPY-Cre and AgRP-Cre animals to activate Arc NPY or AgRP neurons in the presence of food and food-related stimuli. Our findings suggest that chemogenetic activation of the broader population of Arc NPY neurons, including AgRP-positive and AgRP-negative NPY neurons, has equivalent effects on feeding behaviour as activation of Arc AgRP neurons. Our results demonstrate that these Arc NPY neurons respond specifically to caloric signals and do not respond to non-caloric signals, in line with what has been observed in AgRP neurons. Activating Arc NPY neurons significantly increases food consumption and influences macronutrient selection to prefer fat intake.
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Affiliation(s)
- Neda Rafiei
- School of Psychology, University of New South Wales, Australia; School of Pharmacy, University of Sydney, Australia.
| | - Caitlin S Mitchell
- School of Psychology, University of New South Wales, Australia; School of Biomedical Sciences and Pharmacy, University of Newcastle, Australia
| | | | - Jessica Chen
- School of Psychology, University of New South Wales, Australia
| | - Eun A Choi
- School of Psychology, University of New South Wales, Australia
| | | | | | - Natasha N Kumar
- School of Biomedical Sciences, University of New South Wales, Australia
| | - Gavan P McNally
- School of Psychology, University of New South Wales, Australia
| | | | - Denovan P Begg
- School of Psychology, University of New South Wales, Australia
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Gumbs MCR, Eggels L, Vuuregge AH, Unmehopa UA, Mul JD, la Fleur SE. Effects of Neuropeptide Y administration into the lateral hypothalamus on intake of free-choice high-fat high-sucrose diet components of the male Wistar rat. Nutr Neurosci 2020; 25:621-630. [PMID: 32654659 DOI: 10.1080/1028415x.2020.1788774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Introduction: Neuropeptide Y (NPY) signaling in the brain plays an important role in energy regulation, and is altered during diet-induced obesity. Yet, NPY function during the consumption of specific diet components remains to be fully determined. We have previously demonstrated that consumption of a saturated fat component (free-choice high-fat; fcHF), a sucrose solution (high-sugar; fcHS), or both (fcHFHS) combined with a standard diet (chow and water) has diverse effects on Npy expression in the arcuate nucleus and the sensitivity to intraventricular NPY administration. Arcuate NPY neurons project to the lateral hypothalamus (LHA), and NPY administration in the LHA potently promotes chow intake in rats on a standard diet. However, it is currently unclear if short-term consumption of a palatable free-choice diet alters NPY function in the LHA. Therefore, we assessed the effects of intra-LHA NPY administration on intake in rats following one-week consumption of a fcHF, fcHS, or fcHFHS diet.Methods: Male Wistar rats consumed a fcHF, fcHS, fcHFHS, or control (CHOW) diet for one week before NPY (0.3 μg / 0.3 μL) or phosphate-buffered saline (0.3 μL) was administered into the LHA. Intake was measured 2h later. fcHFHS-fed rats were divided into high-fat (fcHFHS-hf) and low-fat (fcHFHS-lf) groups based on differences in basal fat intake.Results: Intra-LHA NPY administration increased chow intake in fcHFHS- (irrespective of basal fat intake), fcHF- and CHOW-fed rats. Intra-LHA NPY infusion increased fat intake in fcHF-, fcHFHS-hf, but not fcHFHS-lf, rats. Intra-LHA NPY infusion did not increase caloric intake in fcHS-fed rats.Discussion: Our data demonstrate that the effects of intra-LHA NPY on caloric intake differ depending on the consumption of a fat or sugar component, or both, in a free-choice diet. Our data also indicate that baseline preference for the fat diet component modulates the effects of intra-LHA NPY in fcHFHS-fed rats.
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Affiliation(s)
- Myrtille C R Gumbs
- Department of Endocrinology and Metabolism & Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Metabolism and Reward group, Netherlands Institute for Neuroscience, An institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, The Netherlands
| | - Leslie Eggels
- Department of Endocrinology and Metabolism & Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Metabolism and Reward group, Netherlands Institute for Neuroscience, An institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, The Netherlands
| | - Anna H Vuuregge
- Metabolism and Reward group, Netherlands Institute for Neuroscience, An institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, The Netherlands
| | - Unga A Unmehopa
- Metabolism and Reward group, Netherlands Institute for Neuroscience, An institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, The Netherlands
| | - Joram D Mul
- Department of Endocrinology and Metabolism & Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Metabolism and Reward group, Netherlands Institute for Neuroscience, An institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, The Netherlands
| | - Susanne E la Fleur
- Department of Endocrinology and Metabolism & Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Metabolism and Reward group, Netherlands Institute for Neuroscience, An institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, The Netherlands
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Romano A, Friuli M, Cifani C, Gaetani S. Oxytocin in the neural control of eating: At the crossroad between homeostatic and non-homeostatic signals. Neuropharmacology 2020; 171:108082. [PMID: 32259527 DOI: 10.1016/j.neuropharm.2020.108082] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 03/10/2020] [Accepted: 03/30/2020] [Indexed: 12/21/2022]
Abstract
The understanding of the biological substrates regulating feeding behavior is relevant to address the health problems related to food overconsumption. Several studies have expanded the conventional view of the homeostatic regulation of body weight mainly orchestrated by the hypothalamus, to include also the non-homeostatic control of appetite. Such processes include food reward and are mainly coordinated by the activation of the central mesolimbic dopaminergic pathway. The identification of endogenous systems acting as a bridge between homoeostatic and non-homeostatic pathways might represent a significant step toward the development of drugs for the treatment of aberrant eating patterns. Oxytocin is a hypothalamic hormone that is directly secreted into the brain and reaches the blood circulation through the neurohypophysis. Oxytocin regulates a variety of physiologic functions, including eating and metabolism. In the last years both preclinical and clinical studies well characterized oxytocin for its effects in reducing food intake and body weight. In the present review we summarize the role played by oxytocin in the control of both homeostatic and non-homeostatic eating, within cognitive, metabolic and reward mechanisms, to mostly highlight its potential therapeutic effects as a new pharmacological approach for the development of drugs for eating disorders. We conclude that the central oxytocinergic system is possibly one of the mechanisms that coordinate energy balance at the crossroads between homeostatic and non-homeostatic mechanisms. This concept should foster studies aimed at exploring the possible exploitation of oxytocin in the treatment of aberrant eating patterns. This article is part of the special issue on Neuropeptides.
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Affiliation(s)
- Adele Romano
- Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, P.le Aldo Moro 5, 00185, Rome, Italy
| | - Marzia Friuli
- Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, P.le Aldo Moro 5, 00185, Rome, Italy
| | - Carlo Cifani
- School of Pharmacy, Pharmacology Unit, University of Camerino, via Madonna delle Carceri, 9, 62032, Camerino, MC, Italy
| | - Silvana Gaetani
- Department of Physiology and Pharmacology "V. Erspamer", Sapienza University of Rome, P.le Aldo Moro 5, 00185, Rome, Italy.
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Gumbs MCR, Eggels L, Kool T, Unmehopa UA, van den Heuvel JK, Lamuadni K, Mul JD, la Fleur SE. Neuropeptide Y Signaling in the Lateral Hypothalamus Modulates Diet Component Selection and is Dysregulated in a Model of Diet-Induced Obesity. Neuroscience 2019; 447:28-40. [PMID: 31887359 DOI: 10.1016/j.neuroscience.2019.12.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 01/16/2023]
Abstract
The preclinical multicomponent free-choice high-fat high-sucrose (fcHFHS) diet has strong validity to model diet-induced obesity (DIO) and associated maladaptive molecular changes in the central nervous system. fcHFHS-induced obese rats demonstrate increased sensitivity to intracerebroventricular infusion of the orexigenic Neuropeptide Y (NPY). The brain region-specific effects of NPY signaling on fcHFHS diet component selection are not completely understood. For example, fcHFHS-fed rats have increased intake of chow and fat following intracerebroventricular NPY infusion, whereas NPY administration in the nucleus accumbens, a key hub of the reward circuitry, specifically increases fat intake. Here, we investigated whether NPY infusion in the lateral hypothalamic area (LHA), which is crucially involved in the regulation of intake, regulates fcHFHS component selection, and if LHA NPY receptor subtypes 1 or 5 (NPYR1/5) are involved. Male Wistar rats were fed a chow or fcHFHS diet for at least seven days, and received intra-LHA vehicle or NPY infusions in a cross-over design. Diet component intake was measured two hours later. Separate experimental designs were used to test the efficacy of NPY1R- or NPY5R antagonism to prevent the orexigenic effects of intra-LHA NPY. Intra-LHA NPY increased caloric intake in chow- and fcHFHS-fed rats. This effect was mediated specifically by chow intake in fcHFHS-fed rats. The orexigenic effects of intra-LHA NPY were prevented by NPY1R and NPY5R antagonism in chow-fed rats, but only by NPY5R antagonism in fcHFHS-fed rats. Thus, NPY signaling has brain region-specific effects on fcHFHS component selection and LHA NPYR sensitivity is dysregulated during consumption of a fcHFHS diet.
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Affiliation(s)
- M C R Gumbs
- Amsterdam UMC, University of Amsterdam, Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; Metabolism and Reward Group, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
| | - L Eggels
- Amsterdam UMC, University of Amsterdam, Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; Metabolism and Reward Group, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
| | - T Kool
- Amsterdam UMC, University of Amsterdam, Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - U A Unmehopa
- Amsterdam UMC, University of Amsterdam, Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - J K van den Heuvel
- Amsterdam UMC, University of Amsterdam, Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - K Lamuadni
- Amsterdam UMC, University of Amsterdam, Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; Metabolism and Reward Group, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
| | - J D Mul
- Amsterdam UMC, University of Amsterdam, Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; Metabolism and Reward Group, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Meibergdreef 47, 1105 BA Amsterdam, The Netherlands; Brain Plasticity Group, Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, Sciencepark 904, 1098 XH Amsterdam, The Netherlands
| | - S E la Fleur
- Amsterdam UMC, University of Amsterdam, Department of Endocrinology and Metabolism and Laboratory of Endocrinology, Department of Clinical Chemistry, Amsterdam Neuroscience, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; Metabolism and Reward Group, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences (KNAW), Meibergdreef 47, 1105 BA Amsterdam, The Netherlands.
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Endocannabinoid and nitric oxide systems of the hypothalamic paraventricular nucleus mediate effects of NPY on energy expenditure. Mol Metab 2018; 18:120-133. [PMID: 30274714 PMCID: PMC6308028 DOI: 10.1016/j.molmet.2018.08.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/14/2018] [Accepted: 08/22/2018] [Indexed: 12/27/2022] Open
Abstract
Objective Neuropeptide Y (NPY) is one of the most potent orexigenic peptides. The hypothalamic paraventricular nucleus (PVN) is a major locus where NPY exerts its effects on energy homeostasis. We investigated how NPY exerts its effect within the PVN. Methods Patch clamp electrophysiology and Ca2+ imaging were used to understand the involvement of Ca2+ signaling and retrograde transmitter systems in the mediation of NPY induced effects in the PVN. Immuno-electron microscopy were performed to elucidate the subcellular localization of the elements of nitric oxide (NO) system in the parvocellular PVN. In vivo metabolic profiling was performed to understand the role of the endocannabinoid and NO systems of the PVN in the mediation of NPY induced changes of energy homeostasis. Results We demonstrated that NPY inhibits synaptic inputs of parvocellular neurons in the PVN by activating endocannabinoid and NO retrograde transmitter systems via mobilization of Ca2+ from the endoplasmic reticulum, suggesting that NPY gates the synaptic inputs of parvocellular neurons in the PVN to prevent the influence of non-feeding-related inputs. While intraPVN administered NPY regulates food intake and locomotor activity via NO signaling, the endocannabinoid system of the PVN selectively mediates NPY-induced decrease in energy expenditure. Conclusion Thus, within the PVN, NPY stimulates the release of endocannabinoids and NO via Ca2+-influx from the endoplasmic reticulum. Both transmitter systems appear to have unique roles in the mediation of the NPY-induced regulation of energy homeostasis, suggesting that NPY regulates food intake, energy expenditure, and locomotor activity through different neuronal networks of this nucleus. NPY increases the intracellular Ca2+ level of PVN neurons by mobilizing the Ca2+ from ER. NPY inhibits the input of these neurons by endocannabinoids and NO. IntraPVN administered NPY regulates food intake and locomotor activity via NO signaling. IntraPVN administered NPY regulates energy expenditure via the endocannabinoid system. NPY regulates the energy expenditure and food intake via different neuronal networks of the PVN.
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Genetic and Neurobiological Analyses of the Noradrenergic-like System in Vulnerability to Sugar Overconsumption Using a Drosophila Model. Sci Rep 2017; 7:17642. [PMID: 29247240 PMCID: PMC5732301 DOI: 10.1038/s41598-017-17760-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 11/30/2017] [Indexed: 12/22/2022] Open
Abstract
Regular overconsumption of sugar is associated with obesity and type-2 diabetes, but how genetic factors contribute to variable sugar preferences and intake levels remains mostly unclear. Here we provide evidence for the usefulness of a Drosophila larva model to investigate genetic influence on vulnerability to sugar overconsumption. Using genetic and RNA interference approaches, we show that the activity of the Oamb gene, which encodes a receptor for octopamine (OA, the invertebrate homologue of norepinephrine), plays a major role in controlled sugar consumption. Furthermore, Oamb appears to suppress sugar food intake in fed larvae in an acute manner, and neurons expressing this Oamb receptor do not overlap with neurons expressing Octβ3R, another OA receptor previously implicated in hunger-driven exuberant sugar intake. Together, these results suggest that two separate sub-circuits, defined by Oamb and Octβ3R respectively, co-regulate sugar consumption according to changes in energy needs. We propose that the noradrenergic-like system defines an ancient regulatory mechanism for prevention of sugar overload.
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7
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Gumbs MC, van den Heuvel JK, la Fleur SE. The effect of obesogenic diets on brain Neuropeptide Y. Physiol Behav 2016; 162:161-73. [DOI: 10.1016/j.physbeh.2016.04.049] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 03/18/2016] [Accepted: 04/26/2016] [Indexed: 12/18/2022]
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8
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Wang G, Tachibana T, Gilbert ER, Cline MA. Dietary Macronutrient Composition Affects the Influence of Exogenous Prolactin-Releasing Peptide on Appetite Responses and Hypothalamic Gene Expression in Chickens. J Nutr 2015; 145:2406-11. [PMID: 26355003 DOI: 10.3945/jn.115.214338] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 07/27/2015] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The interaction between the effects of exogenous neurotransmitters and dietary composition on appetite regulation in nonmammalian species is unclear. OBJECTIVE The objective of this study was to determine the effects of exogenous prolactin-releasing peptide (PrRP) and dietary macronutrient composition on food intake regulation in broiler chicks. METHODS Three isocaloric diets were formulated: high-carbohydrate (HC), high-fat (HF; 60% of ME from lard) and high-protein (HP) diets. In Expt. 1, 4-d-old Hubbard × Cobb-500 chicks fed 1 of the 3 diets since hatch were intracerebroventricularly injected with 0 (vehicle), 3, or 188 pmol PrRP (n = 10). Food intake was measured for 180 min. In Expt. 2, hypothalamic mRNA abundance of appetite-associated factors was measured in hypothalamus samples obtained 1 h postinjection of 0 or 188 pmol PrRP. In Expt. 3, chicks were given free access to all diets before and after intracerebroventricular injection and food intake was measured. RESULTS Three and 188 pmol PrRP increased (P = 0.0008 and 0.04) HP diet intake, but only 188 pmol PrRP was efficacious at increasing HC (P = 0.0011) and HF (P = 0.01) consumption compared with the vehicle. There was a diet effect on mRNA abundance of all genes (P < 0.05), with greater expression in chicks fed the HF or HP than the HC diet. Whereas neuropeptide Y (NPY) mRNA was similar between vehicle- and PrRP-injected chicks that consumed HP or HF diets, expression was greater (P < 0.05) in PrRP- than vehicle-injected chicks that consumed the HC diet. When chicks had access to all diets, 188 pmol PrRP caused preferential (P < 0.0001) intake of the HP over the HC and HF diets. CONCLUSION The HP diet enhanced the sensitivity of chicks to the food intake-stimulating effects of PrRP, and PrRP in turn increased preference for the HP diet. Thus, dietary macronutrient composition influences PrRP-mediated food intake, and PrRP in turn affects nutrient intake and transcriptional regulation in chicks.
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Affiliation(s)
- Guoqing Wang
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA; and
| | - Tetsuya Tachibana
- Department of Agrobiological Science, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Elizabeth R Gilbert
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA; and
| | - Mark A Cline
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA; and
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Tulloch AJ, Murray S, Vaicekonyte R, Avena NM. Neural responses to macronutrients: hedonic and homeostatic mechanisms. Gastroenterology 2015; 148:1205-18. [PMID: 25644095 DOI: 10.1053/j.gastro.2014.12.058] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 12/16/2014] [Accepted: 12/22/2014] [Indexed: 01/15/2023]
Abstract
The brain responds to macronutrients via intricate mechanisms. We review how the brain's neural systems implicated in homeostatic control of feeding and hedonic responses are influenced by the ingestion of specific types of food. We discuss how these neural systems are dysregulated in preclinical models of obesity. Findings from these studies can increase our understanding of overeating and, perhaps in some cases, the development of obesity. In addition, a greater understanding of the neural circuits affected by the consumption of specific macronutrients, and by obesity, might lead to new treatments and strategies for preventing unhealthy weight gain.
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Affiliation(s)
- Alastair J Tulloch
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York
| | - Susan Murray
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York
| | - Regina Vaicekonyte
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York
| | - Nicole M Avena
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York.
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Nelson LA, Gilbert ER, Cline MA. Effects of dietary macronutrient composition on exogenous neuropeptide Y’s stimulation of food intake in chicks. Neurosci Lett 2015; 591:171-175. [DOI: 10.1016/j.neulet.2015.02.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 02/02/2015] [Accepted: 02/07/2015] [Indexed: 10/24/2022]
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Branch A, Bobilev A, Negrao NW, Cai H, Shen P. Prevention of palatable diet-induced hyperphagia in rats by central injection of a VEGFR kinase inhibitor. Behav Brain Res 2015; 278:506-13. [DOI: 10.1016/j.bbr.2014.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/30/2014] [Accepted: 10/02/2014] [Indexed: 12/22/2022]
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12
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Ushimura A, Tsuji T, Tanaka S, Kogo M, Yamamoto T. Neuropeptide-Y modulates eating patterns and masticatory muscle activity in rats. Behav Brain Res 2014; 278:520-6. [PMID: 25447304 DOI: 10.1016/j.bbr.2014.10.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 10/15/2014] [Accepted: 10/20/2014] [Indexed: 11/18/2022]
Abstract
Neuropeptide Y (NPY) is a powerful orexigenic peptide secreted by hypothalamic neurons. The present study investigates how NPY injection into the lateral ventricle modulates masticatory movements and eating behavior. Behavioral experiments showed that cumulative food intake over a 4-h period and latency to eating were increased and decreased, respectively, in NPY-injected rats compared to saline-injected control rats. The feeding time for 2 g pellets was shorter in NPY-injected rats and resulted in an increased feeding rate, with more potent effects observed at 1 μg compared to 10 μg NPY. After injection of 10 μg NPY, a greater number of bouts with shorter average bout duration for eating 2g, compared to 1 μg NPY, were observed. Furthermore, 10 μg NPY injection resulted in prolonged periods of moving and shortened sleep and grooming. Electromyography recordings from the digastric and masseter muscles showed two distinct patterns of bursts corresponding to the gnawing and chewing phases. After the injection of 1 μg NPY, the burst magnitude of masseter muscle during the gnawing phase increased, reflecting strong jaw-closing muscle activity. The relative integrated EMG of masseter muscle in both phases was smaller following injection of 10 μg NPY in comparison with that of 1 μg NPY. The present study indicates that 1 μg NPY administration promotes feeding behavior together with increased feeding rate and powerful jaw-closing muscle activity; whereas 10 μg NPY administration lowers jaw-closing muscle activity during biting and produces mastication with shorter and more frequent feeding bouts than 1 μg NPY.
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Affiliation(s)
- Ayako Ushimura
- First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita City, Osaka 565-0871, Japan
| | - Tadataka Tsuji
- First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita City, Osaka 565-0871, Japan.
| | - Susumu Tanaka
- First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita City, Osaka 565-0871, Japan
| | - Mikihiko Kogo
- First Department of Oral and Maxillofacial Surgery, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita City, Osaka 565-0871, Japan
| | - Takashi Yamamoto
- Department of Health and Nutrition, Faculty of Health Science, Kio University, Koryo-cho, Nara 635-0832, Japan
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van den Heuvel JK, Eggels L, van Rozen AJ, Luijendijk MCM, Fliers E, Kalsbeek A, Adan RAH, la Fleur SE. Neuropeptide Y and leptin sensitivity is dependent on diet composition. J Neuroendocrinol 2014; 26:377-85. [PMID: 24698502 DOI: 10.1111/jne.12155] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 03/26/2014] [Accepted: 03/28/2014] [Indexed: 11/28/2022]
Abstract
Rats on different free-choice (fc) diets for 1 week of either chow, saturated fat and liquid sugar (fcHFHS), chow and saturated fat (fcHF), or chow and liquid sugar (fcHS) have differential levels of neuropeptide Y (NPY) mRNA in the arcuate nucleus. Because these differences were not explained by plasma leptin levels but did predict subsequent feeding behaviour, in the present study, we first examined whether leptin sensitivity could explain these differences. Second, we focused on the role of NPY on feeding behaviour, and measured NPY mRNA levels and sensitivity to NPY after 4 weeks on the different choice diets. To determine leptin sensitivity, we measured food intake after i.p. leptin or vehicle injections in male Wistar rats subjected to the fcHFHS, fcHS, fcHF or Chow diets for 7 days. Next, we measured levels of arcuate nucleus NPY mRNA with in situ hybridisation in rats subjected to the choice diets for 4 weeks. Finally, we studied NPY sensitivity in rats subjected to the fcHFHS, fcHS, fcHF or Chow diet for 4 weeks by measuring food intake after administration of NPY or vehicle in the lateral ventricle. Leptin decreased caloric intake in rats on Chow, fcHS and fcHF but not in rats on the fcHFHS diet. After 4 weeks, rats on the fcHFHS diet remained hyperphagic, whereas fcHS and fcHF rats decreased caloric intake to levels similar to rats on Chow. By contrast to 1 week, after 4 weeks, levels of NPY mRNA were not different between the diet groups. Lateral ventricle administration of NPY resulted in higher caloric intake in fcHFHS rats compared to rats on the other choice diets or rats on Chow. Our data show that consuming a combination of saturated fat and liquid sugar results in leptin resistance and increased NPY sensitivity that is associated with persistent hyperphagia.
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Affiliation(s)
- J K van den Heuvel
- Department of Endocrinology and Metabolism, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
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Covelo IR, Patel ZI, Luviano JA, Stratford TR, Wirtshafter D. Manipulation of GABA in the ventral pallidum, but not the nucleus accumbens, induces intense, preferential, fat consumption in rats. Behav Brain Res 2014; 270:316-25. [PMID: 24867334 DOI: 10.1016/j.bbr.2014.05.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 05/13/2014] [Accepted: 05/16/2014] [Indexed: 12/30/2022]
Abstract
Injections of the GABAA antagonist bicuculline into the medial ventral pallidum (VPm) induce marked increases in food intake, but nothing is known about the way in which these injections alter the distribution of intake in a macronutrient selection situation. We investigated this topic by adapting rats to a diet containing independent sources of protein, carbohydrate and fat, and then examining the effects of intra-VPm bicuculline on diet selection. Under these conditions, bicuculline produced a massive, preferential increase in fat intake with subjects consuming a mean of 97% of their calories from fat. Furthermore, all treated subjects ate fat before any other macronutrient, suggesting that the animals' behavior was directed selectively toward this dietary component even before consumption had begun. Similar effects were not observed following food deprivation, which exerted its largest effect on carbohydrate intake. To compare the intra-VPm bicuculline response to that seen after activation of GABA receptors in the nucleus accumbens shell (AcbSh), a major source of projections to the VPm, we conducted similar experiments with intra-AcbSh injections of muscimol and baclofen. These injections also enhanced food intake, but did not reproduce the selective preference for fat seen after intra-VPm bicuculline. These experiments provide the first demonstration of preferential enhancement of fat intake following manipulations of a nonpeptide neurotransmitter. Since mean intakes of fat under baseline conditions and after deprivation tended to be lower than those of carbohydrates, it seems unlikely that the effects of intra-VPm bicuculline are related to the intrinsic "rewarding" properties of fat, but might rather reflect the induction of a state of "fat craving."
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Affiliation(s)
- Ignacio R Covelo
- Graduate Program in Neuroscience, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607-7137, USA; Department of Psychology (M/C 285), University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607-7137, USA
| | - Zaid I Patel
- Department of Psychology (M/C 285), University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607-7137, USA
| | - Jennifer A Luviano
- Department of Psychology (M/C 285), University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607-7137, USA
| | - Thomas R Stratford
- Laboratory of Integrative Neuroscience, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607-7137, USA; Department of Psychology (M/C 285), University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607-7137, USA.
| | - David Wirtshafter
- Laboratory of Integrative Neuroscience, University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607-7137, USA; Department of Psychology (M/C 285), University of Illinois at Chicago, 1007 West Harrison Street, Chicago, IL 60607-7137, USA
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Orlic-Milacic M, Kaufman L, Mikhailov A, Cheung AYL, Mahmood H, Ellis J, Gianakopoulos PJ, Minassian BA, Vincent JB. Over-expression of either MECP2_e1 or MECP2_e2 in neuronally differentiated cells results in different patterns of gene expression. PLoS One 2014; 9:e91742. [PMID: 24699272 PMCID: PMC3974668 DOI: 10.1371/journal.pone.0091742] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 02/14/2014] [Indexed: 02/01/2023] Open
Abstract
Mutations in MECP2 are responsible for the majority of Rett syndrome cases. MECP2 is a regulator of transcription, and has two isoforms, MECP2_e1 and MECP2_e2. There is accumulating evidence that MECP2_e1 is the etiologically relevant variant for Rett. In this study we aim to detect genes that are differentially transcribed in neuronal cells over-expressing either of these two MECP2 isoforms. The human neuroblastoma cell line SK-N-SH was stably infected by lentiviral vectors over-expressing MECP2_e1, MECP2_e2, or eGFP, and were then differentiated into neurons. The same lentiviral constructs were also used to infect mouse Mecp2 knockout (Mecp2tm1.1Bird) fibroblasts. RNA from these cells was used for microarray gene expression analysis. For the human neuronal cells, ∼800 genes showed >three-fold change in expression level with the MECP2_e1 construct, and ∼230 with MECP2_e2 (unpaired t-test, uncorrected p value <0.05). We used quantitative RT-PCR to verify microarray results for 41 of these genes. We found significant up-regulation of several genes resulting from over-expression of MECP2_e1 including SRPX2, NAV3, NPY1R, SYN3, and SEMA3D. DOCK8 was shown via microarray and qRT-PCR to be upregulated in both SK-N-SH cells and mouse fibroblasts. Both isoforms up-regulated GABRA2, KCNA1, FOXG1 and FOXP2. Down-regulation of expression in the presence of MECP2_e1 was seen with UNC5C and RPH3A. Understanding the biology of these differentially transcribed genes and their role in neurodevelopment may help us to understand the relative functions of the two MECP2 isoforms, and ultimately develop a better understanding of RTT etiology and determine the clinical relevance of isoform-specific mutations.
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Affiliation(s)
- Marija Orlic-Milacic
- Molecular Neuropsychiatry & Development Lab, Campbell Family Mental Health Research Institute, The Centre for Addiction & Mental Health, Toronto, Ontario, Canada
| | - Liana Kaufman
- Molecular Neuropsychiatry & Development Lab, Campbell Family Mental Health Research Institute, The Centre for Addiction & Mental Health, Toronto, Ontario, Canada
| | - Anna Mikhailov
- Molecular Neuropsychiatry & Development Lab, Campbell Family Mental Health Research Institute, The Centre for Addiction & Mental Health, Toronto, Ontario, Canada
| | - Aaron Y. L. Cheung
- Developmental & Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Huda Mahmood
- Molecular Neuropsychiatry & Development Lab, Campbell Family Mental Health Research Institute, The Centre for Addiction & Mental Health, Toronto, Ontario, Canada
| | - James Ellis
- Developmental & Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Peter J. Gianakopoulos
- Molecular Neuropsychiatry & Development Lab, Campbell Family Mental Health Research Institute, The Centre for Addiction & Mental Health, Toronto, Ontario, Canada
| | - Berge A. Minassian
- Program in Genetics & Genomic Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - John B. Vincent
- Molecular Neuropsychiatry & Development Lab, Campbell Family Mental Health Research Institute, The Centre for Addiction & Mental Health, Toronto, Ontario, Canada
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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16
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17
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Bursać BN, Vasiljević AD, Nestorović NM, Veličković NA, Vojnović Milutinović DD, Matić GM, Djordjevic AD. High-fructose diet leads to visceral adiposity and hypothalamic leptin resistance in male rats--do glucocorticoids play a role? J Nutr Biochem 2014; 25:446-55. [PMID: 24565674 DOI: 10.1016/j.jnutbio.2013.12.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 11/29/2013] [Accepted: 12/16/2013] [Indexed: 12/22/2022]
Abstract
Fructose overconsumption has been involved in the genesis and progression of the metabolic syndrome. Hypothalamus and adipose tissue, major organs for control of food intake and energy metabolism, play crucial roles in metabolic homeostasis. We hypothesized that glucocorticoid signaling mediates the effects of a fructose-enriched diet on visceral adiposity by acting on neuropeptide Y (NPY) in the hypothalamus and altering adipogenic transcription factors in the visceral adipose tissue. We analyzed the effects of 9-week consumption of 60% fructose solution on dyslipidemia, insulin and leptin sensitivity, and adipose tissue histology in male Wistar rats. Glucocorticoid signaling was assessed in both hypothalamus and visceral adipose tissue, while the levels of peroxisome-proliferator-activated receptor γ (PPARγ), sterol regulatory element-binding protein-1 (SREBP-1) and lipin-1, together with the levels of their target genes expression, were analyzed in the visceral adipose tissue. The results showed that long-term consumption of highly concentrated liquid fructose led to the development of visceral adiposity, elevated triglycerides and hypothalamic leptin resistance accompanied by stimulated glucocorticoid signaling and NPY mRNA elevation. Results from adipose tissue implied that fructose consumption shifted the balance between glucocorticoid receptor and adipogenic transcriptional factors (PPARγ, SREBP-1 and lipin-1) in favor of adipogenesis judged by distinctly separated populations of small adipocytes observed in this tissue. In summary, we propose that high-fructose-diet-induced alterations of glucocorticoid signaling in both hypothalamus and adipose tissue result in enhanced adipogenesis, possibly serving as an adaptation to energy excess in order to limit deposition of fat in nonadipose tissues.
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Affiliation(s)
- Biljana N Bursać
- Department of Biochemistry, Institute for Biological Research "Siniša Stanković", University of Belgrade, 142 Despot Stefan Blvd., 11000 Belgrade, Serbia
| | - Ana D Vasiljević
- Department of Biochemistry, Institute for Biological Research "Siniša Stanković", University of Belgrade, 142 Despot Stefan Blvd., 11000 Belgrade, Serbia
| | - Nataša M Nestorović
- Department of Cytology, Institute for Biological Research "Siniša Stanković", University of Belgrade, 142 Despot Stefan Blvd., 11000 Belgrade, Serbia
| | - Nataša A Veličković
- Department of Biochemistry, Institute for Biological Research "Siniša Stanković", University of Belgrade, 142 Despot Stefan Blvd., 11000 Belgrade, Serbia
| | - Danijela D Vojnović Milutinović
- Department of Biochemistry, Institute for Biological Research "Siniša Stanković", University of Belgrade, 142 Despot Stefan Blvd., 11000 Belgrade, Serbia
| | - Gordana M Matić
- Department of Biochemistry, Institute for Biological Research "Siniša Stanković", University of Belgrade, 142 Despot Stefan Blvd., 11000 Belgrade, Serbia
| | - Ana D Djordjevic
- Department of Biochemistry, Institute for Biological Research "Siniša Stanković", University of Belgrade, 142 Despot Stefan Blvd., 11000 Belgrade, Serbia.
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Schwetz TA, Ustione A, Piston DW. Neuropeptide Y and somatostatin inhibit insulin secretion through different mechanisms. Am J Physiol Endocrinol Metab 2013; 304:E211-21. [PMID: 23211512 PMCID: PMC3543566 DOI: 10.1152/ajpendo.00374.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pancreatic β-cells regulate glucose homeostasis by secreting insulin in response to glucose elevation and G protein-coupled receptor (GPCR) activation. Neuropeptide Y (NPY) and somatostatin (SST) attenuate insulin secretion through G(i) activation of Y(1) and SSTR(1&5) receptors, respectively. The downstream pathways altered by NPY and SST are poorly understood. Thus, we investigated these underlying mechanisms. NPY and SST increase cellular redox potential, suggesting that their inhibitory effect may not be mediated through metabolic inhibition. NPY does not affect intracellular calcium ([Ca(2+)](i)) activity upon glucose stimulation, whereas SST alters this response. G(βγ)-subunit inhibition by gallein attenuates insulin secretion but does not alter metabolism or [Ca(2+)](i). mSIRK-induced G(βγ) activation does not modulate glucose metabolism but increases [Ca(2+)](i) activity and potentiates insulin release. Cotreatment with gallein and NPY or SST reduces insulin secretion to levels similar to that of gallein alone. mSIRK and NPY cotreatment potentiates insulin secretion similarly to mSIRK alone, whereas mSIRK and SST treatment decreases insulin release. The data support a model where SST attenuates secretion through G(βγ) inhibition of Ca(2+) activity, while NPY activates a Ca(2+)-independent pathway mediated by G(α). GPCR ligands signal through multiple pathways to inhibit insulin secretion, and determining these mechanisms could lead to novel diabetic therapies.
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Affiliation(s)
- Tara A Schwetz
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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19
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Currie PJ, Coiro CD, Duenas R, Guss JL, Mirza A, Tal N. Urocortin I inhibits the effects of ghrelin and neuropeptide Y on feeding and energy substrate utilization. Brain Res 2012; 1385:127-34. [PMID: 21303672 DOI: 10.1016/j.brainres.2011.01.114] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 01/29/2011] [Accepted: 01/31/2011] [Indexed: 02/02/2023]
Abstract
The corticotropin releasing hormone-related ligand, urocortin-I (UcnI), suppresses food intake when injected into multiple hypothalamic and extrahypothalamic areas. UcnI also alters energy substrate utilization, specifically via enhanced fat oxidation as reflected in reductions in respiratory quotient (RQ). In the present study we compared the feeding and metabolic effects of ghrelin and NPY following pretreatment with UcnI. Direct PVN injections of NPY (50 pmol) and ghrelin (50 pmol) were orexigenic while UcnI (10-40 pmol) reliably suppressed food intake. Both ghrelin and NPY increased RQ, indicating enhanced utilization of carbohydrates and the preservation of fat stores. UcnI alone suppressed RQ responses. PVN UcnI attenuated the effects of both ghrelin and NPY on food intake and energy substrate utilization. While ghrelin (5 pmol) potentiated the effect of NPY (25 pmol) on RQ and food intake, these responses were inhibited by pretreatment with UcnI (10 pmol). In conclusion, PVN NPY and ghrelin stimulate eating and promote carbohydrate oxidation while inhibiting fat utilization. These effects are blocked by UcnI which alone suppresses appetite and promotes fat oxidation. Overall these findings are consistent with a possible interactive role of PVN NPY, ghrelin and urocortin in the modulation of appetite and energy metabolism.
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Affiliation(s)
- Paul J Currie
- Department of Psychology, Reed College, 3203 SE Woodstock Blvd, Portland, OR 97202, USA.
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20
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Abstract
When administered into the brain, NPY acts at Y1 and Y5 receptors to increase food intake. The response occurs with a short latency and is quite robust, such that exogenous NPY is generally considered to be the most potent of a growing list of orexigenic compounds that act in the brain. The role of endogenous NPY is not so straightforward, however. Evidence from diverse types of experiments suggests that rather than initiating behavioral eating per se, endogenous NPY elicits autonomic responses that prepare the individual to better cope with consuming a calorically large meal.
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Affiliation(s)
- Adam P Chambers
- Departments of Medicine, University of Cincinnati, OH 45237, USA
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21
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Abstract
The dopaminergic system is involved in the regulation of aggression in many species, especially via dopamine (DA) D1 and D2 receptor pathways. To investigate heritable differences in this regulation, 2 high aggressive strains [Dekalb XL (DXL) and low group egg productivity and survivability (LGPS)] and one low aggressive strain (low group egg productivity and survivability; HGPS) of laying hens were used in the study. The HGPS and LGPS lines were diversely selected using group selection for high and low group production and survivability. The DXL line is a commercial line selected through individual selection based on egg production. Heritable differences in aggressive propensity between the strains have been previously assessed. The birds were pair housed within the same strain and labeled as dominant or subordinate based on behavioral observation. For both experiments 1 and 2, behavioral analysis was performed on all 3 strains whereas neurotransmitter analysis was performed only on the most aggressive (DXL) and least aggressive (HGPS) strains. In experiment 1, the subordinate birds were treated with D1 agonist, D2 agonist, or saline controls (n = 12). In experiment 2, the dominant birds from a separate flock were treated with D1 antagonist, D2 antagonist, or saline controls (n = 12). Treatment-associated changes in aggressive behaviors and central neurotransmitters were measured. Aggression was increased in all strains in response to D1 agonism but increased only in the less aggressive HGPS birds with D2 agonism. Aggression was decreased and hypothalamic serotonin and epinephrine were increased in birds from all strains treated with D2 receptor antagonist. The D1 receptor antagonism elicited different behavioral and neurotransmitter responses based on the aggressive phenotype of the genetic strains. Aggressive strains DXL and LGPS but not the HGPS strain decreased aggressiveness following antagonism of the D1 receptor. The data show evidence for distinct neurotransmitter regulation of aggression in high and low aggressive strains of hens through different receptor systems. These chicken lines could provide new animal models for the biomedical investigation of the genetic basis of aggression.
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Affiliation(s)
- R L Dennis
- Livestock Behavior Research Unit, USDA-ARS, West Lafayette, IN 47907, USA
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Shi YC, Lin S, Castillo L, Aljanova A, Enriquez RF, Nguyen AD, Baldock PA, Zhang L, Bijker MS, Macia L, Yulyaningsih E, Zhang H, Lau J, Sainsbury A, Herzog H. Peripheral-specific y2 receptor knockdown protects mice from high-fat diet-induced obesity. Obesity (Silver Spring) 2011; 19:2137-48. [PMID: 21546930 DOI: 10.1038/oby.2011.99] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Y2 receptors, particularly those in the brain, have been implicated in neuropeptide Y (NPY)-mediated effects on energy homeostasis and bone mass. Recent evidence also indicates a role for Y2 receptors in peripheral tissues in this process by promoting adipose tissue accretion; however their effects on energy balance remain unclear. Here, we show that adult-onset conditional knockdown of Y2 receptors predominantly in peripheral tissues results in protection against diet-induced obesity accompanied by significantly reduced weight gain, marked reduction in adiposity and improvements in glucose tolerance without any adverse effect on lean mass or bone. These changes occur in association with significant increases in energy expenditure, respiratory exchange ratio, and physical activity and despite concurrent hyperphagia. On a chow diet, knockdown of peripheral Y2 receptors results in increased respiratory exchange ratio and physical activity with no effect on lean or bone mass, but decreases energy expenditure without effecting body weight or food intake. These results suggest that peripheral Y2 receptor signaling is critical in the regulation of oxidative fuel selection and physical activity and protects against the diet-induced obesity. The lack of effects on bone mass seen in this model further indicates that bone mass is primarily controlled by non-peripheral Y2 receptors. This study provides evidence that novel drugs that target peripheral rather than central Y2 receptors could provide benefits for the treatment of obesity and glucose intolerance without adverse effects on lean and bone mass, with the additional benefit of avoiding side effects often associated with pharmaceuticals that act on the central nervous system.
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Affiliation(s)
- Yan-Chuan Shi
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
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Lundell I, Rabe Bernhardt N, Johnsson AK, Larhammar D. Internalization studies of chimeric neuropeptide Y receptors Y1 and Y2 suggest complex interactions between cytoplasmic domains. ACTA ACUST UNITED AC 2011; 168:50-8. [DOI: 10.1016/j.regpep.2011.03.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 02/18/2011] [Accepted: 03/28/2011] [Indexed: 11/25/2022]
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Nguyen AD, Herzog H, Sainsbury A. Neuropeptide Y and peptide YY: important regulators of energy metabolism. Curr Opin Endocrinol Diabetes Obes 2011; 18:56-60. [PMID: 21157324 DOI: 10.1097/med.0b013e3283422f0a] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE OF REVIEW An overview of recent developments documenting the neuropeptide Y (NPY) family's role in energy metabolism. Specifically focusing on site-specific functions of NPY and increasing evidence of peptide YY (PYY) as a weight loss therapeutic. RECENT FINDINGS Studying the NPY family in hypothalamic nuclei, other than the arcuate and paraventricular nuclei, is a recent shift in metabolic research. NPY overexpression in the dorsomedial hypothalamus increases food intake whereas its ablation in this area reduces hyperphagia and obesity. Similarly, NPY exerts orexigenic effects in the ventromedial nucleus. However, specific arcuate Y2 receptor ablation leads to positive energy balance, suggesting the NPY family demonstrates location-specific functions. Peripherally, dual blockade of cannabinoid and NPY pathways has synergistic effects on weight loss, as does combined administration of PYY3-36 and oxyntomodulin in reducing food intake, perhaps due to the recently discovered role of PYY in mediating intestinal Gpr119 activity and controlling glucose tolerance. SUMMARY Conditional Y receptor knockout models have provided deeper insights on NPY's functions according to location. Further study of PYY appears vital, due to recent evidence of its role in intestinal motility, with exercise positively influencing PYY levels.
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Affiliation(s)
- Amy D Nguyen
- Neuroscience Research Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
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Shi YC, Lin S, Wong IPL, Baldock PA, Aljanova A, Enriquez RF, Castillo L, Mitchell NF, Ye JM, Zhang L, Macia L, Yulyaningsih E, Nguyen AD, Riepler SJ, Herzog H, Sainsbury A. NPY neuron-specific Y2 receptors regulate adipose tissue and trabecular bone but not cortical bone homeostasis in mice. PLoS One 2010; 5:e11361. [PMID: 20613867 PMCID: PMC2894044 DOI: 10.1371/journal.pone.0011361] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 06/01/2010] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Y2 receptor signalling is known to be important in neuropeptide Y (NPY)-mediated effects on energy homeostasis and bone physiology. Y2 receptors are located post-synaptically as well as acting as auto receptors on NPY-expressing neurons, and the different roles of these two populations of Y2 receptors in the regulation of energy homeostasis and body composition are unclear. METHODOLOGY/PRINCIPAL FINDINGS We thus generated two conditional knockout mouse models, Y2(lox/lox) and NPYCre/+;Y2(lox/lox), in which Y2 receptors can be selectively ablated either in the hypothalamus or specifically in hypothalamic NPY-producing neurons of adult mice. Specific deletion of hypothalamic Y2 receptors increases food intake and body weight compared to controls. Importantly, specific ablation of hypothalamic Y2 receptors on NPY-containing neurons results in a significantly greater adiposity in female but not male mice, accompanied by increased hepatic triglyceride levels, decreased expression of liver carnitine palmitoyltransferase (CPT1) and increased expression of muscle phosphorylated acetyl-CoA carboxylase (ACC). While food intake, body weight, femur length, bone mineral content, density and cortical bone volume and thickness are not significantly altered, trabecular bone volume and number were significantly increased by hypothalamic Y2 deletion on NPY-expressing neurons. Interestingly, in situ hybridisation reveals increased NPY and decreased proopiomelanocortin (POMC) mRNA expression in the arcuate nucleus of mice with hypothalamus-specific deletion of Y2 receptors in NPY neurons, consistent with a negative feedback mechanism between NPY expression and Y2 receptors on NPY-ergic neurons. CONCLUSIONS/SIGNIFICANCE Taken together these data demonstrate the anti-obesogenic role of Y2 receptors in the brain, notably on NPY-ergic neurons, possibly via inhibition of NPY neurons and concomitant stimulation of POMC-expressing neurons in the arcuate nucleus of the hypothalamus, reducing lipogenic pathways in liver and/or skeletal muscle in females. These data also reveal as an anti-osteogenic effect of Y2 receptors on hypothalamic NPY-expressing neurons on trabecular but not on cortical bone.
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Affiliation(s)
- Yan-Chuan Shi
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Shu Lin
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Iris P. L. Wong
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Paul A. Baldock
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Aygul Aljanova
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Ronaldo F. Enriquez
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Lesley Castillo
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Natalie F. Mitchell
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Ji-Ming Ye
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Lei Zhang
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Laurence Macia
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Ernie Yulyaningsih
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Amy D. Nguyen
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Sabrina J. Riepler
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Herbert Herzog
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Amanda Sainsbury
- Neuroscience Research Program, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
- School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
- * E-mail:
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Mahaut S, Dumont Y, Fournier A, Quirion R, Moyse E. Neuropeptide Y receptor subtypes in the dorsal vagal complex under acute feeding adaptation in the adult rat. Neuropeptides 2010; 44:77-86. [PMID: 19880180 DOI: 10.1016/j.npep.2009.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Revised: 10/02/2009] [Accepted: 10/05/2009] [Indexed: 01/14/2023]
Abstract
Neuropeptide Y (NPY), Peptide YY (PYY) and pancreatic polypeptides (PPs) belong to the same peptide family called the Y or NPY family. Central and peripheral injections of these peptides are implicated in the regulation of food intake at the level of the hypothalamus (central effects; increased food intake) and dorsal vagal complex (DVC) (peripheral effects; decreased food intake). The DVC of the brainstem is a satiety reflex key region, which includes the nucleus tractus solitarius (NTS), area postrema (AP) and dorso motor nucleus of the vagus (DMX). NPY binding sites were quantified on serial DVC sections using in vitro receptor autoradiography in two feeding adaptation models: fasting and inflammatory anorexia. Receptor autoradiography revealed that Y(1), Y(2), Y(4) and Y(5) receptor subtypes are present in all nuclei of the DVC. Additionally, we also observed significant amount of specific labelling remaining even after having blocked all known NPY receptor subtypes targeted by radioligands such as [(125)I][Leu(31), Pro(34)]PYY, [(125)I]PYY3-36 and [(125)I]hPP. This binding is referred as an atypical NPY site. Lipopolysaccharide (LPS) injection and food deprivation (24-48h) did not induce any change in the expression of NPY Y(1), Y(2,) Y(4) and Y(5) receptors at the level of the NTS and DMX. However, a significant decrease in [(125)I]PYY3-36/Y(2) and [(125)I]hPP/Y(4)- and Y(5)-insensitive binding sites (residual or atypical site) was observed in the AP. Together, these data could suggest that residual or atypical NPY binding site in the AP is modulated by food deprivation and may be physiologically relevant and implicated in feeding behaviors.
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Affiliation(s)
- Stéphanie Mahaut
- Physiologie Neurovégétative, UMR 6231 CNRS, Université Aix-Marseille-3, Ave. Escadrille Normandie-Niemen, 13397 Marseille cedex 20, France
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Nakhate KT, Dandekar MP, Kokare DM, Subhedar NK. Involvement of neuropeptide Y Y1 receptors in the acute, chronic and withdrawal effects of nicotine on feeding and body weight in rats. Eur J Pharmacol 2009; 609:78-87. [DOI: 10.1016/j.ejphar.2009.03.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 02/17/2009] [Accepted: 03/03/2009] [Indexed: 11/29/2022]
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Lee NJ, Enriquez RF, Boey D, Lin S, Slack K, Baldock PA, Herzog H, Sainsbury A. Synergistic attenuation of obesity by Y2- and Y4-receptor double knockout in ob/ob mice. Nutrition 2008; 24:892-9. [PMID: 18662863 DOI: 10.1016/j.nut.2008.06.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Accepted: 06/19/2008] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Neuropeptide Y regulates numerous processes including food intake, body composition, and reproduction by at least five different Y receptors. We previously demonstrated a synergistic interaction between Y2 and Y4 receptors in reducing adiposity in chow- or fat-fed Y2Y4-receptor double-knockout mice. In the present study, we investigated whether this synergy could reduce the massive obesity of leptin-deficient ob/ob mice. METHODS Mice with germline deletions of Y2 and Y4 receptors were crossed onto the ob/ob strain. Body weight was measured weekly until 15-18 wk of age before decapitation for collection of trunk blood and tissues. RESULTS Male and female Y24ob triple mutants showed highly significant reductions in body weight and white adipose tissue mass compared with ob/ob mice. This reduction in body weight was not evident in Y2ob or Y4ob double mutants, and the effect on adiposity was significantly greater than that seen in Y2ob or Y4ob mice. These changes were associated with significant attenuation of the increased brown adipose tissue mass and small intestinal hypertrophy seen in ob/ob mice and with normalization of the low circulating free thyroxine concentrations seen in female ob/ob mice and the high circulating corticosterone concentrations seen in male ob/ob mice. CONCLUSION These data reveal a synergistic interaction between Y2 and Y4 receptors in attenuating the massive obesity of ob/ob mice, possibly mediated by stimulation of thyroid function and inhibition of intestinal nutrient absorption. Dual pharmacologic antagonism of Y2 and Y4 receptors could help people to attain and maintain a healthy weight.
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Affiliation(s)
- Nicola J Lee
- Neuroscience Research Program, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, New South Wales, Australia
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Gehlert DR, Thompson LK, Hemrick-Luecke SK, Shaw J. Monoaminergic compensation in the neuropeptide Y deficient mouse brain. Neuropeptides 2008; 42:367-75. [PMID: 18329096 DOI: 10.1016/j.npep.2007.10.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Revised: 10/19/2007] [Accepted: 10/20/2007] [Indexed: 11/28/2022]
Abstract
Neuropeptide Y (NPY) is an important central regulator of food consumption and energy expenditure via the hypothalamus. NPY containing neurons have a broad central distribution and are often colocalized with norepinephrine (NE). However, NPY deficient mice do not exhibit any substantial changes in food consumption, body weight or body composition when compared to wild type mice. Since NE and serotonin (5HT) are also important regulators of appetite and metabolism, we evaluated these systems in NPY deficient mice. Brain sections from NPY deficient and wild type mice were labeled with either (3)H-nisoxetine for the NE transporter (NET) or (3)H-citalopram for the 5HT transporter (SERT). Tyrosine hydroxylase expression was evaluated by radioimmunohistochemistry. Brain monoamines and metabolites were evaluated using HPLC. NPY deficient mice exhibited a substantial decrease in NET binding in most brain regions examined. NET binding was less than 50% of control binding in the cerebral cortex and subregions of the thalamus with the greatest decrease seen in the hypothalamus. In contrast, more modest and regionally variable changes were observed in the SERT binding with decreases in regions such as the accessory olfactory nucleus, glomerular layer of the olfactory bulb and the CA1 region of the hippocampus. Measurement of NE and 5HT content as well as the primary metabolites revealed increased NE turnover and decreased 5HT content in the hypothalamus. Therefore, developmental compensation by the NE and 5HT systems may contribute to the absence of a body weight phenotype in NPY deficient mice.
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Affiliation(s)
- Donald R Gehlert
- Neuroscience Discovery Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA.
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Yew JY, Davis R, Dikler S, Nanda J, Reinders B, Stretton AO. Peptide products of the afp-6 gene of the nematode Ascaris suum have different biological actions. J Comp Neurol 2007; 502:872-82. [PMID: 17436302 DOI: 10.1002/cne.21357] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Matrix-assisted laser desorption/ionization time-of-flight and tandem time-of-flight (MALDI-TOF and MALDI-TOF/TOF) mass spectrometry were used to sequence and localize three novel, related neuropeptides in the nervous system of the nematode Ascaris suum, AMRNALVRFamide (AF21), NGAPQPFVRFamide (AF22), and SGMRNALVRFamide (AF23). The amino acid sequences were used to clone a novel neuropeptide gene (afp-6) that encodes a precursor bearing a single copy of each of the peptides. In situ hybridization and immunocytochemistry revealed that both the transcript and the peptides are expressed in a single cell in the ventral ganglion. Pharmacological studies of intact nematodes injected with these peptides, as well as physiological studies of responses to them in muscle tissue, motor neurons, and the pharynx, reveal that these peptides have potent bioactivity in the locomotory and feeding systems. Further exploration of their effects may contribute to our understanding of neuropeptide modulation of behavior and also to the development of compounds with anthelmintic relevance.
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Affiliation(s)
- Joanne Y Yew
- Department of Zoology, University of Wisconsin, Madison, Wisconsin 53706, USA.
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Coletta DK, Schneider J, Stern MP, Blangero J, DeFronzo RA, Duggirala R, Jenkinson CP. Association of neuropeptide Y receptor Y5 polymorphisms with dyslipidemia in Mexican Americans. Obesity (Silver Spring) 2007; 15:809-15. [PMID: 17426313 DOI: 10.1038/oby.2007.610] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We examined the genetic association of neuropeptide Y receptor Y5 (NPY5R) single nucleotide polymorphisms (SNPs) with measures of the insulin resistance (metabolic) syndrome. We genotyped 10 NPY5R SNPs in 439 Mexican American individuals (age=43.3+/-17.3 years and BMI=30.0+/-6.7 kg/m2) distributed across 27 pedigrees from the San Antonio Family Diabetes Study and performed association analyses using the measured genotype approach as implemented in Sequential Oligogenic Linkage Analysis Routines (SOLAR). Minor alleles for five (rs11100493, rs12501691, P1, rs11100494, rs12512687) of the NPY5R SNPs were found to be significantly (p<0.05) associated with fasting plasma triglyceride concentrations and decreased high-density lipoprotein concentrations. In addition, the minor allele for SNP P2 was significantly associated (p=0.031) with a decreased homeostasis model assessment of beta-cell function (HOMA-%beta). Linkage disequilibrium between SNP pairs indicated one haplotype block of five SNPs (rs11100493, rs12501691, P1, rs11100494, rs12512687) that were highly correlated (r2>0.98). These preliminary results provide evidence for association of SNPs in the NPY5R gene with dyslipidemia (elevated triglyceride concentrations and reduced high-density lipoprotein levels) in our Mexican American population.
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Affiliation(s)
- Dawn K Coletta
- Division of Diabetes MC 7886, Department of Medicine, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
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32
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Beck B. Hypothalamic galanin and early state of hyperphagia in obese Zucker rats. Appetite 2007; 48:206-10. [PMID: 17055610 DOI: 10.1016/j.appet.2006.09.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Revised: 08/23/2006] [Accepted: 09/07/2006] [Indexed: 11/24/2022]
Abstract
Galanin (GAL) stimulates food intake in normal rats when it is injected in different hypothalamic areas involved in feeding such as the paraventricular and ventromedial nuclei and the lateral hypothalamus. At adulthood, the hyperphagic obese Zucker rat is characterized by a general dysregulation of some important neuropeptides involved in the regulation of food intake including GAL. The aim of this study was to measure GAL in different microdissected brain areas in 2- and 4-week-old lean (FA/-) and obese (fa/fa) male Zucker rats in order to know if GAL actively participates in triggering abnormal feeding behavior in obese rats. There was a significant increase (40%-220%) in GAL concentration with age in the arcuate and dorsomedial nuclei and in the above areas except for the lateral hypothalamus. Genotype differences were observed in the arcuate and paraventricular nuclei only. GAL levels were globally lower in obese than in lean rats (-15% to -25%) and the difference was significant at 2 weeks of age in the paraventricular nucleus and at 4 weeks of age in the arcuate nucleus. In agreement with human observations, these data suggest that GAL is not an early player in the development of overeating.
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Affiliation(s)
- Bernard Beck
- INSERM, U308 Mécanismes de Régulation du Comportement Alimentaire, 54000 NANCY, France.
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Beck B. Neuropeptide Y in normal eating and in genetic and dietary-induced obesity. Philos Trans R Soc Lond B Biol Sci 2007; 361:1159-85. [PMID: 16874931 PMCID: PMC1642692 DOI: 10.1098/rstb.2006.1855] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Neuropeptide Y (NPY) is one the most potent orexigenic peptides found in the brain. It stimulates food intake with a preferential effect on carbohydrate intake. It decreases latency to eat, increases motivation to eat and delays satiety by augmenting meal size. The effects on feeding are mediated through at least two receptors, the Y1 and Y5 receptors. The NPY system for feeding regulation is mostly located in the hypothalamus. It is formed of the arcuate nucleus (ARC), where the peptide is synthesized, and the paraventricular (PVN), dorsomedial (DMN) and ventromedial (VMN) nuclei and perifornical area where it is active. This activity is modulated by the hindbrain and limbic structures. It is dependent on energy availability, e.g. upregulation with food deprivation or restriction, and return to baseline with refeeding. It is also sensitive to diet composition with variable effects of carbohydrates and fats. Leptin signalling and glucose sensing which are directly linked to diet type are the most important factors involved in its regulation. Absence of leptin signalling in obesity models due to gene mutation either at the receptor level, as in the Zucker rat, the Koletsky rat or the db/db mouse, or at the peptide level, as in ob/ob mouse, is associated with increased mRNA abundance, peptide content and/or release in the ARC or PVN. Other genetic obesity models, such as the Otsuka-Long-Evans-Tokushima Fatty rat, the agouti mouse or the tubby mouse, are characterized by a diminution in NPY expression in the ARC nucleus and by a significant increase in the DMN. Further studies are necessary to determine the exact role of NPY in these latter models. Long-term exposure to high-fat or high-energy palatable diets leads to the development of adiposity and is associated with a decrease in hypothalamic NPY content or expression, consistent with the existence of a counter-regulatory mechanism to diminish energy intake and limit obesity development. On the other hand, an overactive NPY system (increased mRNA expression in the ARC associated with an upregulation of the receptors) is characteristic of rats or rodent strains sensitive to dietary-induced obesity. Finally, NPY appears to play an important role in body weight and feeding regulation, and while it does not constitute the only target for drug treatment of obesity, it may nevertheless provide a useful target in conjunction with others.
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Affiliation(s)
- B Beck
- Université Henri Poincaré, Neurocal, Nancy, France.
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Gruninger TR, LeBoeuf B, Liu Y, Garcia LR. Molecular signaling involved in regulating feeding and other mitivated behaviors. Mol Neurobiol 2007; 35:1-20. [PMID: 17519503 DOI: 10.1007/bf02700621] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Revised: 11/30/1999] [Accepted: 09/06/2006] [Indexed: 12/29/2022]
Abstract
The metabolic and nutritional status of an organism influences multiple behaviors in addition to food intake. When an organism is hungry, it employs behaviors that help it locate and ingest food while suppressing behaviors that are not associated with this goal. Alternatively, when an organism is satiated, food-seeking behaviors are repressed so that the animal can direct itself to other goal-oriented tasks such as reproductive behaviors. Studies in both vertebrate and invertebrate model systems have revealed that food-deprived and -satiated behaviors are differentially executed and integrated via common molecular signaling mechanisms. This article discusses cellular and molecular mechanisms for how insulin, neuropeptide Y (NPY), and serotonin utilize common signaling pathways to integrate feeding and metabolic state with other motivated behaviors. Insulin, NPY, and serotonin are three of the most well-studied molecules implicated in regulating such behaviors. Overall, insulin signaling allows an organism to coordinate proper behavioral output with changes in metabolism, NPY activates behaviors required for locating and ingesting food, and serotonin modulates behaviors performed when an organism is satiated. These three molecules work to ensure that the proper behaviors are executed in response to the feeding state of an organism.
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Affiliation(s)
- Todd R Gruninger
- Department of Biology, Texas A&M University, TAMU 3258, College Station, TX, USA
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35
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Tentolouris N, Liatis S, Katsilambros N. Sympathetic System Activity in Obesity and Metabolic Syndrome. Ann N Y Acad Sci 2006; 1083:129-52. [PMID: 17148737 DOI: 10.1196/annals.1367.010] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Obesity is a very common disease worldwide, resulting from a disturbance in the energy balance. The metabolic syndrome is also a cluster of abnormalities with basic characteristics being insulin resistance and visceral obesity. The major concerns of obesity and metabolic syndrome are the comorbidities, such as type 2 diabetes, cardiovascular disease, stroke, and certain types of cancers. Sympathetic nervous system (SNS) activity is associated with both energy balance and metabolic syndrome. Sympathomimetic medications decrease food intake, increase resting metabolic rate (RMR), and thermogenic responses, whereas blockage of the SNS exerts opposite effects. The contribution of the SNS to the daily energy expenditure, however, is small ( approximately 5%) in normal subjects consuming a weight maintenance diet. Fasting suppresses, whereas meal ingestion induces SNS activity. Most of the data agree that obesity is characterized by SNS predominance in the basal state and reduced SNS responsiveness after various sympathetic stimuli. Weight loss reduces SNS overactivity in obesity. Metabolic syndrome is characterized by enhanced SNS activity. Most of the indices used for the assessment of its activity are better associated with visceral fat than with total fat mass. Visceral fat is prone to lipolysis: this effect is mediated by catecholamine action on the sensitive beta(3)-adrenoceptors found in the intraabdominal fat. In addition, central fat distribution is associated with disturbances in the hypothalamo-pituitary-adrenal axis, suggesting that a disturbed axis may be implicated in the development of the metabolic syndrome. Furthermore, SNS activity induces a proinflammatory state by IL-6 production, which in turn results in an acute phase response. The increased levels of inflammatory markers seen in the metabolic syndrome may be elicited, at least in part, by SNS overactivity. Intervention studies showed that the disturbances of the autonomic nervous system seen in the metabolic syndrome are reversible.
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Affiliation(s)
- N Tentolouris
- 1st Department of Propaedeutic Medicine, Athens University Medical School, 11523 Athens, Greece.
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36
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Leptin. GYNAKOLOGISCHE ENDOKRINOLOGIE 2006. [DOI: 10.1007/s10304-005-0135-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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37
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Israel Y, Kandov Y, Khaimova E, Kest A, Lewis SR, Pasternak GW, Pan YX, Rossi GC, Bodnar RJ. NPY-induced feeding: pharmacological characterization using selective opioid antagonists and antisense probes in rats. Peptides 2005; 26:1167-75. [PMID: 15949635 DOI: 10.1016/j.peptides.2005.01.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Revised: 01/20/2005] [Accepted: 01/24/2005] [Indexed: 11/17/2022]
Abstract
The ability of neuropeptide Y to potently stimulate food intake is dependent in part upon the functioning of mu and kappa opioid receptors. The combined use of selective opioid antagonists directed against mu, delta or kappa receptors and antisense probes directed against specific exons of the MOR-1, DOR-1, KOR-1 and KOR-3/ORL-1 opioid receptor genes has been successful in characterizing the precise receptor subpopulations mediating feeding elicited by opioid peptides and agonists as well as homeostatic challenges. The present study examined the dose-dependent (5-80 nmol) cerebroventricular actions of general and selective mu, delta, and kappa1 opioid receptor antagonists together with antisense probes directed against each of the four exons of the MOR-1 opioid receptor gene and each of the three exons of the DOR-1, KOR-1, and KOR-3/ORL-1 opioid receptor genes upon feeding elicited by cerebroventricular NPY (0.47 nmol, 2 ug). NPY-induced feeding was dose-dependently decreased and sometimes eliminated following pretreatment with general, mu, delta, and kappa1 opioid receptor antagonists. Moreover, NPY-induced feeding was significantly and markedly reduced by antisense probes directed against exons 1, 2, and 3 of the MOR-1 gene, exons 1 and 2 of the DOR-1 gene, exons 1, 2, and 3 of the KOR-1 gene, and exon 3 of the KOR-3/ORL-1 gene. Thus, whereas the opioid peptides, beta-endorphin and dynorphin A(1-17) elicit feeding responses that are respectively more dependent upon mu and kappa opioid receptors and their genes, the opioid mediation of NPY-induced feeding appears to involve all three major opioid receptor subtypes in a manner similar to that observed for feeding responses following glucoprivation or lipoprivation.
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Affiliation(s)
- Y Israel
- Department of Psychology, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367, USA
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38
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Gardiner JV, Kong WM, Ward H, Murphy KG, Dhillo WS, Bloom SR. AAV mediated expression of anti-sense neuropeptide Y cRNA in the arcuate nucleus of rats results in decreased weight gain and food intake. Biochem Biophys Res Commun 2005; 327:1088-93. [PMID: 15652508 DOI: 10.1016/j.bbrc.2004.12.113] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Indexed: 10/26/2022]
Abstract
Neuropeptide Y (NPY) is the most potent stimulant of feeding when administered by intracerebroventricular injection. Despite this, there is conflicting evidence as to its importance in the regulation of daily food intake and energy balance. It has been suggested that whilst it is important in the response to starvation it has little role in the regulation of daily food intake. To investigate the role of NPY in the regulation of food intake, anti-sense cRNA to NPY was expressed in the arcuate nucleus of adult male rats. The anti-sense NPY (AS-NPY) construct was initially tested in vitro and there was a decrease of approximately 50% in NPY release from anti-sense treated cells compared to controls (16.3 +/- 2.0 fmol/L [AS-NPY] vs 37.3 +/- 7.7 fmol/L [control], mean +/- SEM p < 0.05). NPY release from hypothalamic explants from anti-sense injected animals was decreased by over 50% compared to those from controls at both 15 and 20 days after AAV injection (15 days 42% +/- 6.5% [AS-NPY] vs 100% +/- 36% [control], 20 days 41% +/- 6% [AS-NPY] vs 100% +/- 27% [control] mean+/-SEM, p < 0.05). In a study lasting for 50 days, weight gain was significantly lower in anti-sense injected animals from day 16 (day 16: 6.25 +/- 1.10 g [AS-NPY] vs 9.42 +/- 0.65 g [control] mean +/- SEM, p < 0.05) and remained so until the end of the study when they had gained approximately 40% less weight than controls (day 50: 52.0 +/- 9.6 g [AS-NPY] vs 82.0 +/- 6.3 g [control] mean +/- SEM, p < 0.01). Cumulative food intake was significantly lower in the anti-sense injected animals from day 23 (day 23: 225.8 +/- 1.9 g [AS-NPY] vs 250.6 +/- 8.7 g [control], mean +/- SEM, p < 0.05) and remained so until the end of the study (day 50: 834.5 +/- 14.8 g [AS-NPY] vs 926.0 +/- 31.7 g [control], mean +/- SEM, p < 0.05). Similarly mean daily food intake was also reduced in the anti-sense injected animals (days 7-14: 24.9 +/- 0.4 g/day [AS-NPY] vs 27.2 +/- 0.4 g/day [control], mean +/- SEM, p < 0.01). These data are supportive of a role for NPY in the regulation of daily food intake as well as in response to starvation.
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Affiliation(s)
- J V Gardiner
- Metabolic Medicine, Hammersmith Campus, Imperial College London, London W12 0NN, UK
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Lin L, York DA. Amygdala enterostatin induces c-Fos expression in regions of hypothalamus that innervate the PVN. Brain Res 2004; 1020:147-53. [PMID: 15312796 DOI: 10.1016/j.brainres.2004.06.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2004] [Indexed: 11/19/2022]
Abstract
Enterostatin selectively inhibits the intake of the dietary fat after both central and peripheral administration. Our previous studies have shown that a central site of action is the central nucleus of amygdala. Serotonergic agonists administered into the paraventricular nucleus (PVN) inhibit fat intake and serotonergic antagonists block the feeding suppression induced by amygdala enterostatin, suggesting that there are functional connections between the PVN and amygdala that affect the feeding response to enterostatin. Our purpose was to identify the anatomic and functional projections from the amygdala to the PVN and hypothalamic area that are responsive to enterostatin, by using a retrograde tracer fluorogold (FG) and c-Fos expression. Rats were injected with fluorogold unilaterally into the PVN and a chronic amygdala cannula was implanted ipsilaterally. After 10 days recovery, rats were injected with either enterostatin (0.1 nmol) or saline vehicle (0.1 microl) into the amygdala and sacrificed 2 h later by cardiac perfusion under anesthesia. The brains were subjected to dual immunohistochemistry to visualize both FG and c-Fos-positive cells. FG/c-Fos double-labeled cells were found in forebrain regions including the PVN, amygdala, lateral hypothalamus (LH), ventral medial hypothalamus (VMH) and arcuate nucleus (ARC). The data provides the first anatomical evidence that enterostatin activates amygdala neurons that have functional and anatomic projections directly to the PVN and also activates neurons in the arcuate, LH and VMH, which innervate the PVN.
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Affiliation(s)
- Ling Lin
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USA.
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40
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Abstract
Energy balance is maintained via a homeostatic system involving both the brain and the periphery. A key component of this system is the hypothalamus. Over the past two decades, major advances have been made in identifying an increasing number of peptides within the hypothalamus that contribute to the process of energy homeostasis. Under stable conditions, equilibrium exists between anabolic peptides that stimulate feeding behavior, as well as decrease energy expenditure and lipid utilization in favor of fat storage, and catabolic peptides that attenuate food intake, while stimulating sympathetic nervous system (SNS) activity and restricting fat deposition by increasing lipid metabolism. The equilibrium between these neuropeptides is dynamic in nature. It shifts across the day-night cycle and from day to day and also in response to dietary challenges as well as peripheral energy stores. These shifts occur in close relation to circulating levels of the hormones, leptin, insulin, ghrelin and corticosterone, and also the nutrients, glucose and lipids. These circulating factors together with neural processes are primary signals relaying information regarding the availability of fuels needed for current cellular demand, in addition to the level of stored fuels needed for long-term use. Together, these signals have profound impact on the expression and production of neuropeptides that, in turn, initiate the appropriate anabolic or catabolic responses for restoring equilibrium. In this review, we summarize the evidence obtained on nine peptides in the hypothalamus that have emerged as key players in this process. Data from behavioral, physiological, pharmacological and genetic studies are described and consolidated in an attempt to formulate a clear statement on the underlying function of each of these peptides and also on how they work together to create and maintain energy homeostasis.
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Affiliation(s)
- Sarah F Leibowitz
- Laboratory of Behavioral Neurobiology, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
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41
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Mahmoodi M, Gardiner JV, Ghatei MA, Asadikaram G, Bloom SR. Investigation of the chronic effects of NPY by subcutaneous implantation of 6-23 cells producing NPY in WAG rats. Clin Biochem 2004; 37:217-23. [PMID: 14972644 DOI: 10.1016/j.clinbiochem.2003.11.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2003] [Revised: 09/04/2003] [Accepted: 11/07/2003] [Indexed: 11/20/2022]
Abstract
OBJECTIVE In this experiment, we studied the chronic effects of NPY, as there were no data on long-term effects of NPY in vivo. METHODS Complementary DNA encoding NPY was isolated, sequenced and cloned into the expression vector, pCEP4. The 6-23 clone 6 cell line was transfected with this clone. Two groups of 10 adult male WAG rats (180-250 g body weight) were injected with either untransfected 6-23 clone 6 or 6-23 clone 6 transfected with NPY cDNA [6-23 (NPY)]. After 8 weeks, the animals were killed, their plasma assayed for insulin. Pancreatic glucagon (PG), by RIA, and plasma glucose were measured. RESULTS The transfected cells were shown to be producing fully processed, bioactive NPY. The expression of NPY was also confirmed by Northern blot analysis. The animals injected with 6-23 (NPY) cells gained significantly more weight than the controls, (on day 54, 31.89 +/- 3.56 vs. 24.1 +/- 4.12 g, n = 10, P < 0.05). Plasma insulin and PG increased significantly in NPY animals compared to controls. The total RNA extracted from tumours was analysed by Northern blotting and showed NPY mRNA expression in NPY animals, but not in controls. CONCLUSION The long-term effects of NPY was confirmed by injection of the cells producing this peptide.
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Affiliation(s)
- Mehdi Mahmoodi
- Department of Biochemistry, Rafsanjan School of Medicine, Rafsanjan, Iran.
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Hettes SR, Gonzaga J, Heyming TW, Perez S, Wolfsohn S, Stanley BG. Dual roles in feeding for AMPA/kainate receptors: receptor activation or inactivation within distinct hypothalamic regions elicits feeding behavior. Brain Res 2003; 992:167-78. [PMID: 14625056 DOI: 10.1016/j.brainres.2003.08.032] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have previously shown that hypothalamic injections of glutamate, or agonists of its ionotropic receptors (iGluRs), elicit intense feeding responses in satiated rats [Brain Res. 613 (1993) 88, Brain Res. 630 (1993) 41]. While attempting to clarify the role of the AMPA and kainate (KA) receptor subtypes in glutamatergic feeding systems, we discovered that lateral hypothalamic (LH) injection of high doses of the competitive AMPA/KA receptor antagonist, NBQX (10 and 30 nmol), elicited a pronounced feeding response. We questioned whether this effect was due to inactivation of AMPA or possibly KA receptors. To determine whether other AMPA/KA antagonists can also elicit feeding, we tested whether injection of CNQX, another AMPA/KA receptor antagonist, also stimulates eating and whether these feeding stimulatory effects were due to antagonists' actions in the LH or in other hypothalamic sites. Here we report that NBQX and CNQX elicit feeding in a dose dependent manner and are most effective when injected into the perifornical hypothalamus (PFH), or into the paraventricular nucleus (PVN) and, to a lesser extent, into the LH of satiated rats. In contrast, AMPA was most effective in stimulating feeding when injected into the LH, confirming previous reports. These data suggest that either activation or inactivation of AMPA/KA receptors in distinct but overlapping hypothalamic sites may be sufficient to induce feeding behavior, indicating a broadened role for glutamate in hypothalamic feeding mechanisms.
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MESH Headings
- 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology
- Animals
- Dose-Response Relationship, Drug
- Feeding Behavior/drug effects
- Feeding Behavior/physiology
- Glutamic Acid/metabolism
- Hypothalamic Area, Lateral/cytology
- Hypothalamic Area, Lateral/drug effects
- Hypothalamic Area, Lateral/metabolism
- Hypothalamus/cytology
- Hypothalamus/drug effects
- Hypothalamus/metabolism
- Male
- Neural Pathways/cytology
- Neural Pathways/drug effects
- Neural Pathways/metabolism
- Paraventricular Hypothalamic Nucleus/cytology
- Paraventricular Hypothalamic Nucleus/drug effects
- Paraventricular Hypothalamic Nucleus/metabolism
- Quinoxalines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, AMPA/agonists
- Receptors, AMPA/antagonists & inhibitors
- Receptors, AMPA/metabolism
- Receptors, Kainic Acid/agonists
- Receptors, Kainic Acid/antagonists & inhibitors
- Receptors, Kainic Acid/metabolism
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/pharmacology
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Affiliation(s)
- Stacey R Hettes
- Neuroscience Graduate Program, University of California-Riverside,Riverside, CA 92521, USA.
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43
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Fraley GS, Ritter S. Immunolesion of norepinephrine and epinephrine afferents to medial hypothalamus alters basal and 2-deoxy-D-glucose-induced neuropeptide Y and agouti gene-related protein messenger ribonucleic acid expression in the arcuate nucleus. Endocrinology 2003; 144:75-83. [PMID: 12488332 DOI: 10.1210/en.2002-220659] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Neuropeptide Y (NPY) and agouti gene-related protein (AGRP) are orexigenic peptides of special importance for control of food intake. In situ hybridization studies have shown that NPY and AGRP mRNAs are increased in the arcuate nucleus of the hypothalamus (ARC) by glucoprivation. Other work has shown that glucoprivation stimulates food intake by activation of hindbrain glucoreceptor cells and requires the participation of rostrally projecting norepinephrine (NE) or epinephrine (E) neurons. Here we determine the role of hindbrain catecholamine afferents in glucoprivation-induced increase in ARC NPY and AGRP gene expression. The selective NE/E immunotoxin saporin-conjugated antidopamine-beta-hydroxylase (anti-dbetah) was microinjected into the medial hypothalamus and expression of AGRP and NPY mRNA was analyzed subsequently in the ARC under basal and glucoprivic conditions using (33)P-labeled in situ hybridization. Saporin-conjugated anti-dbetah virtually eliminated dbetah-immunoreactive terminals in the ARC without causing nonspecific damage. These lesions significantly increased basal but eliminated 2-deoxy-D-glucose-induced increases in AGRP and NPY mRNA expression. Results indicate that hindbrain catecholaminergic neurons contribute to basal NPY and AGRP gene expression and mediate the responsiveness of NPY and AGRP neurons to glucose deficit. Our results also suggest that catecholamine neurons couple potent orexigenic neural circuitry within the hypothalamus with hindbrain glucose sensors that monitor brain glucose supply.
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Affiliation(s)
- G S Fraley
- Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Pullman, Washington 99164-6520, USA
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44
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Currie PJ, Coiro CD, Niyomchai T, Lira A, Farahmand F. Hypothalamic paraventricular 5-hydroxytryptamine: receptor-specific inhibition of NPY-stimulated eating and energy metabolism. Pharmacol Biochem Behav 2002; 71:709-16. [PMID: 11888562 DOI: 10.1016/s0091-3057(01)00671-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The feeding effects of 5-hydroxytryptamine (5-HT)(1) and 5-HT(2) receptor agonists injected into the hypothalamic paraventricular nucleus (PVN) immediately prior to PVN administration of neuropeptide Y (NPY) were examined. The impact of these same compounds on NPY-induced alterations in energy metabolism was also assessed in an attempt to characterize further the potential interactive relationship of PVN NPY and 5-HT on feeding and whole body calorimetry. Specifically, several experiments examined the effect of various 5-HT receptor agonists on NPY-stimulated eating and alterations in energy substrate utilization [respiratory quotient (RQ)]. This included the 5-HT(1A) receptor agonist 8-OH-DPAT, the 5-HT(1B/1A) agonist RU 24969, the 5-HT(1D) agonist L-694,247, the 5-HT(2A/2C) agonist DOI, the 5-HT(2B) agonist BW 723C86 and the 5-HT(2C) agonist mCPP. In feeding tests conducted at the onset of the dark cycle, drugs were administered 5 min prior to PVN injection of NPY and food intake was measured 2 h postinjection. The metabolic effects of NPY following a similar pretreatment were monitored using an open-circuit calorimeter measuring the volume of oxygen consumed (VO(2)), carbon dioxide produced (VCO(2)) and RQ (VCO(2)/VO(2)). PVN injection of NPY (100 pmol) potentiated feeding and evoked reliable increases in RQ. Only DOI (2.5--5 nmol) pretreatment antagonized NPY-induced eating and blocked the peptide's effect on energy substrate utilization. Direct PVN pretreatment with spiperone (SPRN), a 5-HT(2A) receptor antagonist, and ketanserin (KTSN), a 5-HT(2A/2C) antagonist, but not SDZ SER 082, a 5-HT(2B/2C) antagonist, or the 5-HT(2C) antagonist RS 102221, blocked the effect of DOI in both feeding and metabolic tests providing additional evidence that activation of PVN 5-HT(2A) receptors inhibits NPY's action on feeding and substrate utilization.
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Affiliation(s)
- Paul J Currie
- Department of Psychology, Barnard College, Columbia University, 3009 Broadway, New York, NY 10027, USA.
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45
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Singh SN, Vats P, Shyam R, Suri S, Kumria MM, Ranganathan S, Sridharan K, Selvamurthy W. Role of neuropeptide Y and galanin in high altitude induced anorexia in rats. Nutr Neurosci 2002; 4:323-31. [PMID: 11842898 DOI: 10.1080/1028415x.2001.11747372] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Anorexia causing weight loss at high altitude (HA) is a major problem. Neuropeptide Y (NPY) and galanin are considered to have appetite regulatory function. The present study was therefore undertaken to investigate the changes in these two peptides at simulated HA and its possible role in anorexia. Male Sprague-Dawley rats (n = 8 in each group) were exposed to simulated HA (7620 m) for 1, 7, 14 and 21 days for 6 h a day and to an altitude of 6,096 m for 72 h to study the effect of intermittent and continuous exposure, respectively. NPY and galanin levels were estimated in different brain parts and plasma of exposed and unexposed control animals. Significant reduction in food intake was observed in rats during both intermittent as well as continuous exposure. In case of 72 h continuous exposure severe reduction in food intake was observed (73.2%) with reduction in body mass (approximately 29.7g/rat in 48h). Hypothalamic NPY levels were decreased by 54.7, 35.0 and 15.4% in 1, 7, and 14 days, respectively, in case of intermittent exposure to HA. However in case of 72 h HA exposure no significant change in hypothalamic and circulating NPY levels were observed. Plasma galanin levels were decreased in both intermittent and 72 h continuous HA exposed rats. Hypothalamic galanin levels were also decreased in 72h exposed rats. The changes in levels of these peptides may be responsible for anorexia at HA.
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Affiliation(s)
- S N Singh
- Defence Institute of Physiology and Allied Sciences, Timarpur, Delhi, India.
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46
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Narnaware YK, Peter RE. Influence of diet composition on food intake and neuropeptide Y (NPY) gene expression in goldfish brain. REGULATORY PEPTIDES 2002; 103:75-83. [PMID: 11786146 DOI: 10.1016/s0167-0115(01)00342-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In this study, goldfish demonstrate preference for high carbohydrate and high fat diets, with no preference shown for high protein diets. Fish fed high (45% and 55%) carbohydrate (CHO) diets for 1 and 4 weeks exhibited decreased NPY gene expression in telencephalon-preoptic area (TEL-POA) and optic tectum-thalamus (OT-THAL) compared to fish fed low CHO (35% and 40%) diets. In hypothalamus (HYP), NPY gene expression was significantly increased after 1 week in fish fed both low and high CHO diets compared to control diet (40% CHO); after 4 weeks, the pattern in HYP was reversed. Fish fed a high fat (9%) diet had low NPY gene expression in TEL-POA after 1 and 4 weeks; however, HYP NPY expression was increased in fish fed a low (3%) fat diet after 1 week, and 2% and 3% fat diets after 4 weeks. In OT-THAL, NPY gene expression was decreased in fish fed a 2% fat diet for 1 week, and increased after 4 weeks. Feeding diets with different protein contents for 1 or 4 weeks did not influence NPY gene expression in goldfish brain. The results demonstrate, for the first time in a lower vertebrate, that NPY gene expression in goldfish brain is influenced by macronutrient intake.
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Affiliation(s)
- Yuwaraj K Narnaware
- Biological Sciences Building, University of Alberta, Alberta, Edmonton, T6G 2E9, Canada
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47
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Currie PJ, Coscina DV, Bishop C, Coiro CD, Koob GF, Rivier J, Vale W. Hypothalamic paraventricular nucleus injections of urocortin alter food intake and respiratory quotient. Brain Res 2001; 916:222-8. [PMID: 11597609 DOI: 10.1016/s0006-8993(01)02851-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Corticotropin releasing hormone (CRH) acts on the central nervous system to alter energy balance and influence both food intake and sympathetically-mediated thermogenesis. CRH is also reported to inhibit food intake in several models of hyperphagia including neuropeptide Y (NPY)-induced eating. The recently identified CRH-related peptide, urocortin (UCN), also binds with high affinity to CRH receptor subtypes and decreases food intake in food-deprived and non-deprived rats. The present experiment characterized further the feeding and metabolic effects of UCN by examining its impact after direct injections into the paraventricular nucleus (PVN) of the hypothalamus. In feeding tests (n=8), UCN (50-200 pmol) was injected into the PVN at the onset of the dark cycle and food intake was measured 1, 2 and 4 h postinjection. In separate rats (n=8), the metabolic effects of UCN were monitored using an open circuit calorimeter which measured oxygen consumption (V(O2)) and carbon dioxide production (V(CO2)). Respiratory quotient (RQ) was calculated as V(CO2)/V(O2). UCN suppressed feeding at all times studied and reliably decreased RQ within 30 min of infusion. Additional work examined the effect of UCN (50-100 pmol) pretreatment on the feeding and metabolic effects of NPY. NPY, injected at the start of the dark period, reliably increased 2 h food intake. This effect was blocked by PVN UCN administration. Similarly, UCN blocked the increase in RQ elicited by NPY alone. These results suggest that UCN-sensitive mechanisms within the PVN may modulate food intake and energy substrate utilization, possibly through an interaction with hypothalamic NPY.
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Affiliation(s)
- P J Currie
- Department of Psychology, Barnard College, Columbia University, New York, NY 10027, USA.
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48
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Sainsbury A, Herzog H. Inhibitory effects of central neuropeptide Y on the somatotropic and gonadotropic axes in male rats are independent of adrenal hormones. Peptides 2001; 22:467-71. [PMID: 11287103 DOI: 10.1016/s0196-9781(01)00342-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Neuropeptide Y (NPY) in the hypothalamus exerts multiple physiological functions including stimulation of adipogenic pathways such as feeding and insulin secretion as well as inhibition of the somatotropic and gonadotropic axes. Since hypothalamic NPY-ergic activity is increased by negative energy balance, NPY enables coordinated regulation of growth and reproduction in parallel with energy availability. Chronic pathological increases in central NPY-ergic activity contribute to obesity. Many of the adipogenic effects of NPY are specifically dependent on adrenal glucocorticoids. However, in the current study we show that central NPY does not require adrenal hormones to inhibit the somatotropic and gonadotropic axes in rats. Male adrenalectomized and sham-operated normal rats were intracerebroventricularly (ICV) infused with NPY (15 microg/day) or saline for 5-7 days, and plasma leptin, insulin-like growth factor (IGF-1) and testosterone were assayed, and epididymal white adipose tissue (WATe) was weighed. In normal intact rats, WATe weight and leptinemia were significantly increased by NPY, and these effects were prevented by adrenalectomy. In normal rats, NPY markedly reduced plasma IGF-1 levels (470 +/- 40 versus 1260 +/- 90 ng/ml) and testosterone (0.53 +/- 0.28 versus 5.4 +/- 0.80 nmol/l in saline-infused controls, p < 0.0001). Adrenalectomy decreased plasma IGF-1 concentrations to 290 +/- 30 (p < 0.0001 versus normal rats), which were significantly reduced further by NPY. However, adrenalectomy had no significant effect on basal nor on NPY-induced plasma testosterone concentrations. In conclusion unlike the stimulatory effects of NPY on fat mass and leptinemia, NPY-induced inhibition of the somatotropic and gonadotropic axes in male rats do not require adrenal hormones.
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Affiliation(s)
- A Sainsbury
- Diabetes Research Group, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst NSW 2010, Sydney, Australia
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Bray MS, Boerwinkle E, Hanis CL. Linkage analysis of candidate obesity genes among the Mexican-American population of Starr County, Texas. Genet Epidemiol 2000; 16:397-411. [PMID: 10207720 DOI: 10.1002/(sici)1098-2272(1999)16:4<397::aid-gepi6>3.0.co;2-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Recent advances in the molecular basis of body fat regulation have identified several genes in which genetic variation may influence obesity and related measures in human populations. Genes that have been shown to have a regulatory function in the control of body fat utilization, eating behavior, and/or metabolic rate in rodent models of obesity include leptin (LEP), leptin receptor (LEPR), neuropeptide Y (NPY), NPY Y1 receptor (NPYY1), glucagon-like peptide-1 (GLP-1), GLP-1 receptor (GLP1R), and uncoupling protein 1 (UCP1). We have typed microsatellite markers located within or near these seven candidate obesity genes in 302 non-diabetic individuals from 59 Mexican-American families from Starr County, Texas. Sib pair linkage analysis was used to examine linkage between these genes and obesity status (obese siblings only; n = 170 pairs) and several obesity-related quantitative variables (all siblings; n = 545 total sibling pairs). Significant linkage (P = 0.042) was found between obesity and NPY within the obese sibling pairs. No other candidate gene was linked to obesity status in this subsample. Consistent with the obese sib pair linkage results, NPY showed evidence of linkage to body weight (P = 0.020), abdominal circumference (P = 0.031), hip circumference (P = 0.012), diastolic blood pressure (P = 0.005), and a composite measure of body mass and size (P = 0.048) in the entire sibling sample. Other significant linkages observed were between LEP and waist/hip ratio (P = 0.010), total cholesterol (P = 0.030), and HDL cholesterol (P = 0.026) and between LEPR and fasting blood glucose (P = 0.018) and diastolic blood pressure (P = 0.003). These results support further investigation of NPY, LEP, and LEPR to identify genetic variation that may influence obesity status, glucose and lipid metabolism, and blood pressure in Mexican Americans.
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Affiliation(s)
- M S Bray
- Human Genetics Center, University of Texas-Houston Health Science Center, Graduate School of Biomedical Sciences 77225, USA
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50
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Bishop C, Currie PJ, Coscina DV. Effects of three neurochemical stimuli on delayed feeding and energy metabolism. Brain Res 2000; 865:139-47. [PMID: 10814743 DOI: 10.1016/s0006-8993(00)02310-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Infusions of norepinephrine (NE), the gamma-aminobutyric acid agonist, muscimol (MUS), or neuropeptide Y (NPY) into the paraventricular nucleus (PVN) of the hypothalamus all increase food intake. Such feeding may be due to direct activation of behavioral processes driving ingestion and/or to alterations in nutrient metabolism that feeding serves to normalize. To examine these possibilities, male Sprague-Dawley rats received PVN infusions of vehicle, 20 nmol NE, 1 nmol MUS or 100 pmol NPY at dark onset, then food intake was measured under three feeding conditions: (1) 1 and 2 h immediately after injections, (2) 1 h after a 1 h delay between injections and access to food, and (3) 1 h after a 1 h feeding delay, but with injections occurring just before presenting food. Measures of energy expenditure (EE) and respiratory quotients (RQs) in the absence of food were made over 2 h in parallel experiments. Results confirmed that NE, MUS and NPY all increased dark-onset feeding, but only NPY increased intake above control levels after a 1 h feeding delay. No neurochemically-induced changes in EE were observed, nor were there changes in RQs after NE or MUS. However, NPY reliably enhanced RQs from 30 to 120 min of testing. Our findings imply that NE and MUS initiate relatively immediate, short-term feeding that is not associated with changes in nutrient metabolism and does not summate with cues stimulated by delayed access to food. NPY initiates more protracted feeding temporally linked to enhanced carbohydrate metabolism. This may indicate that part of NPY's feeding stimulatory effects are secondary to physiological processes driving ingestion.
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Affiliation(s)
- C Bishop
- Department of Psychology, Wayne State University, 71 W. Warren Ave., Detroit, MI 48202, USA.
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