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Nie T, Zhang S, Vazhoor Amarsingh G, Liu H, McCann MJ, Cooper GJS. Altered metabolic gene expression in the brain of a triprolyl-human amylin transgenic mouse model of type 2 diabetes. Sci Rep 2019; 9:14588. [PMID: 31601900 PMCID: PMC6787337 DOI: 10.1038/s41598-019-51088-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 09/24/2019] [Indexed: 12/12/2022] Open
Abstract
Type 2 diabetes mellitus is a major health concern worldwide; however, the molecular mechanism underlying its development is poorly understood. The hormone amylin is postulated to be involved, as human amylin forms amyloid in the pancreases of diabetic patients, and oligomers have been shown to be cytotoxic to β-cells. As rodent amylin is non-amyloidogenic, mice expressing human amylin have been developed to investigate this hypothesis. However, it is not possible to differentiate the effects of amylin overexpression from β-cell loss in these models. We have developed transgenic mice that overexpress [25, 28, 29 triprolyl]human amylin, a non-amyloidogenic variant of amylin, designated the Line 44 model. This model allows us to investigate the effects of chronic overexpression of non-cytotoxic amylin. We characterised this model and found it developed obesity, hyperglycaemia and hyperinsulinaemia. This phenotype was associated with alterations in the expression of genes involved in the amylin, insulin and leptin signalling pathways within the brain. This included genes such as c-Fos (a marker of amylin activation); Socs3 (a leptin inhibitor); and Cart, Pomc and Npy (neuropeptides that control appetite). We also examined Socs3 protein expression and phosphorylated Stat3 to determine if changes at the mRNA level would be reflected at the protein level.
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Affiliation(s)
- Tina Nie
- School of Biological Sciences, Faculty of Science, the University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Shaoping Zhang
- School of Biological Sciences, Faculty of Science, the University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.,The Maurice Wilkins Centre for Molecular Biodiscovery, Faculty of Science, the University of Auckland, Auckland, New Zealand
| | - Greeshma Vazhoor Amarsingh
- School of Biological Sciences, Faculty of Science, the University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Hong Liu
- School of Biological Sciences, Faculty of Science, the University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Mark J McCann
- Food Nutrition & Health Team, AgResearch Ltd, Grasslands Research Centre, Palmerston North, 4442, New Zealand
| | - Garth J S Cooper
- School of Biological Sciences, Faculty of Science, the University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand. .,The Maurice Wilkins Centre for Molecular Biodiscovery, Faculty of Science, the University of Auckland, Auckland, New Zealand. .,Centre for Advanced Discovery and Experimental Therapeutics, Division of Cardiovascular Sciences, Faculty of Biology Medicine & Health, School of Medical Sciences, the University of Manchester, Manchester, M13 9NT, United Kingdom.
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Eerola K, Virtanen S, Vähätalo L, Ailanen L, Cai M, Hruby V, Savontaus M, Savontaus E. Hypothalamic γ-melanocyte stimulating hormone gene delivery reduces fat mass in male mice. J Endocrinol 2018; 239:19–31. [PMID: 30307151 DOI: 10.1530/joe-18-0009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
γ-Melanocyte stimulating hormone (γ-MSH) is an endogenous agonist of the melanocortin 3-receptor (MC3R). Genetic disruption of MC3Rs increases adiposity and blunts responses to fasting, suggesting that increased MC3R signaling could be physiologically beneficial in the long term. Interestingly, several studies have concluded that activation of MC3Rs is orexigenic in the short term. Therefore, we aimed to examine the short- and long-term effects of γ-MSH in the hypothalamic arcuate nucleus (ARC) on energy homeostasis and hypothesized that the effect of MC3R agonism is dependent on the state of energy balance and nutrition. Lentiviral gene delivery was used to induce a continuous expression of γ-Msh only in the ARC of male C57Bl/6N mice. Parameters of body energy homeostasis were monitored as food was changed from chow (6 weeks) to Western diet (13 weeks) and back to chow (7 weeks). The γ-MSH treatment decreased the fat mass to lean mass ratio on chow, but the effect was attenuated on Western diet. After the switch back to chow, an enhanced loss in weight (−15% vs −6%) and fat mass (−37% vs −12%) and reduced cumulative food intake were observed in γ-MSH-treated animals. Fasting-induced feeding was increased on chow diet only; however, voluntary running wheel activity on Western diet was increased. The γ-MSH treatment also modulated the expression of key neuropeptides in the ARC favoring weight loss. We have shown that a chronic treatment intended to target ARC MC3Rs modulates energy balance in nutritional state-dependent manner. Enhancement of diet-induced weight loss could be beneficial in treatment of obesity.
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Affiliation(s)
- K Eerola
- Institute of Biomedicine, Research Center for Integrative Physiology and Pharmacology and Turku Center for Disease Modeling, University of Turku, Turku, Finland
- Turku Centre for Biotechnology, University of Turku, Turku, Finland
| | - S Virtanen
- Institute of Biomedicine, Research Center for Integrative Physiology and Pharmacology and Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - L Vähätalo
- Institute of Biomedicine, Research Center for Integrative Physiology and Pharmacology and Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - L Ailanen
- Institute of Biomedicine, Research Center for Integrative Physiology and Pharmacology and Turku Center for Disease Modeling, University of Turku, Turku, Finland
- Drug Research Doctoral Program, University of Turku, Turku, Finland
| | - M Cai
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA
| | - V Hruby
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA
| | - M Savontaus
- Turku Centre for Biotechnology, University of Turku, Turku, Finland
- Heart Center, Turku University Hospital and University of Turku, Turku, Finland
| | - E Savontaus
- Institute of Biomedicine, Research Center for Integrative Physiology and Pharmacology and Turku Center for Disease Modeling, University of Turku, Turku, Finland
- Unit of Clinical Pharmacology, Turku University Hospital, Turku, Finland
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Smith JK. Exercise, Obesity and CNS Control of Metabolic Homeostasis: A Review. Front Physiol 2018; 9:574. [PMID: 29867590 PMCID: PMC5965103 DOI: 10.3389/fphys.2018.00574] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 04/30/2018] [Indexed: 01/12/2023] Open
Abstract
This review details the manner in which the central nervous system regulates metabolic homeostasis in normal weight and obese rodents and humans. It includes a review of the homeostatic contributions of neurons located in the hypothalamus, the midbrain and limbic structures, the pons and the medullary area postrema, nucleus tractus solitarius, and vagus nucleus, and details how these brain regions respond to circulating levels of orexigenic hormones, such as ghrelin, and anorexigenic hormones, such as glucagon-like peptide 1 and leptin. It provides an insight as to how high intensity exercise may improve homeostatic control in overweight and obese subjects. Finally, it provides suggestions as to how further progress can be made in controlling the current pandemic of obesity and diabetes.
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Affiliation(s)
- John K Smith
- Departments of Academic Affairs and Biomedical Science, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, United States
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Dezfuli G, Gillis RA, Tatge JE, Duncan KR, Dretchen KL, Jackson PG, Verbalis JG, Sahibzada N. Subdiaphragmatic Vagotomy With Pyloroplasty Ameliorates the Obesity Caused by Genetic Deletion of the Melanocortin 4 Receptor in the Mouse. Front Neurosci 2018; 12:104. [PMID: 29545738 PMCID: PMC5838008 DOI: 10.3389/fnins.2018.00104] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 02/12/2018] [Indexed: 12/22/2022] Open
Abstract
Background/Objectives: We tested the hypothesis that abolishing vagal nerve activity will reverse the obesity phenotype of melanocortin 4 receptor knockout mice (Mc4r−/−). Subjects/Methods: In two separate studies, we examined the efficacy of bilateral subdiaphragmatic vagotomy (SDV) with pyloroplasty in the prevention and treatment of obesity in Mc4r−/− mice. Results: In the first study, SDV prevented >20% increase in body weight (BW) associated with this genotype. This was correlated with a transient reduction in overall food intake (FI) in the preventative arm of the study. Initially, SDV mice had reduced weekly FI; however, FI normalized to that of controls and baseline FI within the 8-week study period. In the second study, the severe obesity that is characteristic of the adult Mc4r−/− genotype was significantly improved by SDV with a magnitude of 30% loss in excess BW over a 4-week period. Consistent with the first preventative study, within the treatment arm, SDV mice also demonstrated a transient reduction in FI relative to control and baseline levels that normalized over subsequent weeks. In addition to the accompanying loss in weight, mice subjected to SDV showed a decrease in respiratory exchange ratio (RER), and an increase in locomotor activity (LA). Analysis of the white fat-pad deposits of these mice showed that they were significantly less than the control groups. Conclusions: Altogether, our data demonstrates that SDV both prevents gain in BW and causes weight loss in severely obese Mc4r−/− mice. Moreover, it suggests that an important aspect of weight reduction for this type of monogenic obesity involves loss of signaling in vagal motor neurons.
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Affiliation(s)
- Ghazaul Dezfuli
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
| | - Richard A Gillis
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
| | - Jaclyn E Tatge
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
| | - Kimbell R Duncan
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
| | - Kenneth L Dretchen
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
| | - Patrick G Jackson
- Department of Surgery, Georgetown University Medical Center, Washington, DC, United States
| | - Joseph G Verbalis
- Department of Medicine, Georgetown University Medical Center, Washington, DC, United States
| | - Niaz Sahibzada
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
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Côté I, Sakarya Y, Kirichenko N, Morgan D, Carter CS, Tümer N, Scarpace PJ. Activation of the central melanocortin system chronically reduces body mass without the necessity of long-term caloric restriction. Can J Physiol Pharmacol 2016; 95:206-214. [PMID: 28051332 DOI: 10.1139/cjpp-2016-0290] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Melanotan II (MTII) is a potent appetite suppressor that rapidly reduces body mass. Given the rapid loss of anorexic response upon chronic MTII treatment, most investigations have focused on the initial physiological adaptations. However, other evidence supports MTII as a long-term modulator of energy balance that remains to be established. Therefore, we examined the chronic effects of MTII on energy homeostasis. MTII (high or low dose) or artificial cerebrospinal fluid (aCSF) was infused into the lateral ventricle of the brain of 6-month-old F344BN rats (6-7/group) over 40 days. MTII suppressed appetite in a dose-dependent manner (P < 0.05). Although food intake promptly rose back to control level, body mass was persistently reduced in both MTII groups (P < 0.01). At day 40, both MTII groups displayed lower adiposity than the aCSF animals (P < 0.01). These results show that MTII chronically reduces body mass without the requirement of long-term caloric restriction. Our study proposes that food restriction helps initiate mass loss; however, combined with a secondary pharmacological approach preserving a negative energy balance state over time may help combat obesity.
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Affiliation(s)
- I Côté
- a Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Y Sakarya
- a Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA.,b Geriatric Research, Education, and Clinical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL, USA
| | - N Kirichenko
- a Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA.,b Geriatric Research, Education, and Clinical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL, USA
| | - D Morgan
- c Department of Psychiatry, University of Florida, Gainesville, FL, USA
| | - C S Carter
- d Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA
| | - N Tümer
- a Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA.,b Geriatric Research, Education, and Clinical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL, USA
| | - P J Scarpace
- a Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
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Mountjoy KG. Pro-Opiomelanocortin (POMC) Neurones, POMC-Derived Peptides, Melanocortin Receptors and Obesity: How Understanding of this System has Changed Over the Last Decade. J Neuroendocrinol 2015; 27:406-18. [PMID: 25872650 DOI: 10.1111/jne.12285] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 04/04/2015] [Accepted: 04/07/2015] [Indexed: 12/19/2022]
Abstract
Following the cloning of the melanocortin receptor and agouti protein genes, a model was developed for the central melanocortin system with respect to the regulation of energy and glucose homeostasis. This model comprised leptin regulation of melanocortin peptides and agouti-related peptide (AgRP) produced from central pro-opiomelanocortin (POMC) and AgRP neurones, respectively, as well as AgRP competitive antagonism of melanocortin peptides activating melanocortin 4 receptor (MC4R) to Gαs and the cAMP signalling pathway. In the last decade, there have been paradigm shifts in our understanding of the central melanocortin system as a result of the application of advanced new technologies, including Cre-LoxP transgenic mouse technology, pharmacogenetics and optogenetics. During this period, our understanding of G protein coupled receptor signal transduction has also dramatically changed, such that these receptors are now known to exist in the plasma membrane oscillating between various inactive and active conformational states, and the active states signal through G protein-dependent and G protein-independent pathways. The present review focuses on evidence obtained over the past decade that has changed our understanding of POMC gene expression and regulation in the central nervous system, POMC and AgRP neuronal circuitry, neuroanatomical functions of melanocortin receptors, melanocortin 3 receptor (MC3R) and MC4R, and signal transduction through MC3R and MC4R.
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Affiliation(s)
- K G Mountjoy
- Departments of Physiology and Molecular Medicine and Pathology, School of Medical Sciences, Faculty of Medical and Health Sciences and Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand
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7
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Wang D, He X, Zhao Z, Feng Q, Lin R, Sun Y, Ding T, Xu F, Luo M, Zhan C. Whole-brain mapping of the direct inputs and axonal projections of POMC and AgRP neurons. Front Neuroanat 2015; 9:40. [PMID: 25870542 PMCID: PMC4375998 DOI: 10.3389/fnana.2015.00040] [Citation(s) in RCA: 185] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 03/12/2015] [Indexed: 01/21/2023] Open
Abstract
Pro-opiomelanocortin (POMC) neurons in the arcuate nucleus (ARC) of the hypothalamus and nucleus tractus solitarius (NTS) of the brainstem play important roles in suppressing food intake and maintaining energy homeostasis. Previous tract-tracing studies have revealed the axonal connection patterns of these two brain areas, but the intermingling of POMC neurons with other neuron types has made it challenging to precisely identify the inputs and outputs of POMC neurons. In this study, we used the modified rabies virus to map the brain areas that provide direct inputs to the POMC neurons in the ARC and NTS as well as the inputs to the ARC AgRP neurons for comparison. ARC POMC neurons receive inputs from dozens of discrete structures throughout the forebrain and brainstem. The brain areas containing the presynaptic partners of ARC POMC neurons largely overlap with those of ARC AgRP neurons, although POMC neurons receive relatively broader, denser inputs. Furthermore, POMC neurons in the NTS receive direct inputs predominantly from the brainstem and show very different innervation patterns for POMC neurons in the ARC. By selectively expressing fluorescent markers in the ARC and NTS POMC neurons, we found that almost all of their major presynaptic partners are innervated by POMC neurons in the two areas, suggesting that there are strong reciprocal projections among the major POMC neural pathways. By comprehensively chartering the whole-brain connections of the central melanocortin system in a cell-type-specific manner, this study lays the foundation for dissecting the roles and underlying circuit mechanisms of specific neural pathways in regulating energy homeostasis.
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Affiliation(s)
- Daqing Wang
- School of Life Sciences, Tsinghua University Beijing China ; National Institute of Biological Sciences Beijing, China
| | - Xiaobing He
- Key Laboratory of Magnetic Resonance in Biological Systems and State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences Wuhan, China ; University of Chinese Academy of Sciences Beijing, China
| | - Zhe Zhao
- National Institute of Biological Sciences Beijing, China
| | - Qiru Feng
- National Institute of Biological Sciences Beijing, China
| | - Rui Lin
- National Institute of Biological Sciences Beijing, China
| | - Yue Sun
- National Institute of Biological Sciences Beijing, China
| | - Ting Ding
- Key Laboratory of Magnetic Resonance in Biological Systems and State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences Wuhan, China
| | - Fuqiang Xu
- Key Laboratory of Magnetic Resonance in Biological Systems and State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences Wuhan, China ; University of Chinese Academy of Sciences Beijing, China ; Wuhan National Laboratory for Optoelectronics Wuhan, China
| | - Minmin Luo
- School of Life Sciences, Tsinghua University Beijing China ; National Institute of Biological Sciences Beijing, China
| | - Cheng Zhan
- National Institute of Biological Sciences Beijing, China
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Eerola K, Rinne P, Penttinen AM, Vähätalo L, Savontaus M, Savontaus E. α-MSH overexpression in the nucleus tractus solitarius decreases fat mass and elevates heart rate. J Endocrinol 2014; 222:123-36. [PMID: 24829220 DOI: 10.1530/joe-14-0064] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The POMC pathway is involved in the regulation of energy and cardiovascular homeostasis in the hypothalamus and the brain stem. Although the acute effects of POMC-derived peptides in different brain locations have been elucidated, the chronic site-specific effects of distinct peptides remain to be studied. To this end, we used a lentiviral gene delivery vector to study the long-term effects of α-MSH in the nucleus tractus solitarius (NTS) of the brain stem. The α-MSH vector (LVi-α-MSH-EGFP) based on the N-terminal POMC sequence and a control vector (LVi-EGFP) were delivered into the NTS of C57BL/6N male mice fed on a western diet. Effects on body weight and composition, feeding, glucose metabolism, and hemodynamics by telemetric analyses were studied during the 12-week follow-up. The LVi-α-MSH-EGFP-treated mice had a significantly smaller gain in the fat mass compared with LVi-EGFP-injected mice. There was a small initial decrease in food intake and no differences in the physical activity. Glucose metabolism was not changed compared with the control. LVi-α-MSH-EGFP increased the heart rate (HR), which was attenuated by adrenergic blockade suggesting an increased sympathetic activity. Reduced response to muscarinic blockade suggested a decreased parasympathetic activity. Fitting with sympathetic activation, LVi-α-MSH-EGFP treatment reduced urine secretion. Thus, the results demonstrate that long-term α-MSH overexpression in the NTS attenuates diet-induced obesity. Modulation of autonomic nervous system tone increased the HR and most probably contributed to an anti-obesity effect. The results underline the key role of NTS in the α-MSH-induced long-term effects on adiposity and in regulation of sympathetic and parasympathetic activities.
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Affiliation(s)
- K Eerola
- Department of PharmacologyDrug Development and Therapeutics and Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520 Turku, FinlandTurku Centre for BiotechnologyUniversity of Turku, Turku, FinlandDrug Research Doctoral ProgramUniversity of Turku, Turku, FinlandHeart CenterTurku University Hospital and University of Turku, Turku, FinlandUnit of Clinical PharmacologyTurku University Hospital, Turku, FinlandDepartment of PharmacologyDrug Development and Therapeutics and Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520 Turku, FinlandTurku Centre for BiotechnologyUniversity of Turku, Turku, FinlandDrug Research Doctoral ProgramUniversity of Turku, Turku, FinlandHeart CenterTurku University Hospital and University of Turku, Turku, FinlandUnit of Clinical PharmacologyTurku University Hospital, Turku, FinlandDepartment of PharmacologyDrug Development and Therapeutics and Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520 Turku, FinlandTurku Centre for BiotechnologyUniversity of Turku, Turku, FinlandDrug Research Doctoral ProgramUniversity of Turku, Turku, FinlandHeart CenterTurku University Hospital and University of Turku, Turku, FinlandUnit of Clinical PharmacologyTurku University Hospital, Turku, Finland
| | - P Rinne
- Department of PharmacologyDrug Development and Therapeutics and Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520 Turku, FinlandTurku Centre for BiotechnologyUniversity of Turku, Turku, FinlandDrug Research Doctoral ProgramUniversity of Turku, Turku, FinlandHeart CenterTurku University Hospital and University of Turku, Turku, FinlandUnit of Clinical PharmacologyTurku University Hospital, Turku, Finland
| | - A M Penttinen
- Department of PharmacologyDrug Development and Therapeutics and Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520 Turku, FinlandTurku Centre for BiotechnologyUniversity of Turku, Turku, FinlandDrug Research Doctoral ProgramUniversity of Turku, Turku, FinlandHeart CenterTurku University Hospital and University of Turku, Turku, FinlandUnit of Clinical PharmacologyTurku University Hospital, Turku, Finland
| | - L Vähätalo
- Department of PharmacologyDrug Development and Therapeutics and Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520 Turku, FinlandTurku Centre for BiotechnologyUniversity of Turku, Turku, FinlandDrug Research Doctoral ProgramUniversity of Turku, Turku, FinlandHeart CenterTurku University Hospital and University of Turku, Turku, FinlandUnit of Clinical PharmacologyTurku University Hospital, Turku, FinlandDepartment of PharmacologyDrug Development and Therapeutics and Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520 Turku, FinlandTurku Centre for BiotechnologyUniversity of Turku, Turku, FinlandDrug Research Doctoral ProgramUniversity of Turku, Turku, FinlandHeart CenterTurku University Hospital and University of Turku, Turku, FinlandUnit of Clinical PharmacologyTurku University Hospital, Turku, Finland
| | - M Savontaus
- Department of PharmacologyDrug Development and Therapeutics and Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520 Turku, FinlandTurku Centre for BiotechnologyUniversity of Turku, Turku, FinlandDrug Research Doctoral ProgramUniversity of Turku, Turku, FinlandHeart CenterTurku University Hospital and University of Turku, Turku, FinlandUnit of Clinical PharmacologyTurku University Hospital, Turku, FinlandDepartment of PharmacologyDrug Development and Therapeutics and Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520 Turku, FinlandTurku Centre for BiotechnologyUniversity of Turku, Turku, FinlandDrug Research Doctoral ProgramUniversity of Turku, Turku, FinlandHeart CenterTurku University Hospital and University of Turku, Turku, FinlandUnit of Clinical PharmacologyTurku University Hospital, Turku, Finland
| | - E Savontaus
- Department of PharmacologyDrug Development and Therapeutics and Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520 Turku, FinlandTurku Centre for BiotechnologyUniversity of Turku, Turku, FinlandDrug Research Doctoral ProgramUniversity of Turku, Turku, FinlandHeart CenterTurku University Hospital and University of Turku, Turku, FinlandUnit of Clinical PharmacologyTurku University Hospital, Turku, FinlandDepartment of PharmacologyDrug Development and Therapeutics and Turku Center for Disease Modeling, University of Turku, Kiinamyllynkatu 10, 20520 Turku, FinlandTurku Centre for BiotechnologyUniversity of Turku, Turku, FinlandDrug Research Doctoral ProgramUniversity of Turku, Turku, FinlandHeart CenterTurku University Hospital and University of Turku, Turku, FinlandUnit of Clinical PharmacologyTurku University Hospital, Turku, Finland
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9
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Stevanovic DM, Grefhorst A, Themmen APN, Popovic V, Holstege J, Haasdijk E, Trajkovic V, van der Lely AJ, Delhanty PJD. Unacylated ghrelin suppresses ghrelin-induced neuronal activity in the hypothalamus and brainstem of male rats [corrected]. PLoS One 2014; 9:e98180. [PMID: 24852945 PMCID: PMC4031147 DOI: 10.1371/journal.pone.0098180] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 04/29/2014] [Indexed: 01/03/2023] Open
Abstract
Ghrelin, the endogenous growth hormone secretagogue, has an important role in metabolic homeostasis. It exists in two major molecular forms: acylated (AG) and unacylated (UAG). Many studies suggest different roles for these two forms of ghrelin in energy balance regulation. In the present study, we compared the effects of acute intracerebroventricular administration of AG, UAG and their combination (AG+UAG) to young adult Wistar rats on food intake and central melanocortin system modulation. Although UAG did not affect food intake it significantly increased the number of c-Fos positive neurons in the arcuate (ARC), paraventricular (PVN) and solitary tract (NTS) nuclei. In contrast, UAG suppressed AG-induced neuronal activity in PVN and NTS. Central UAG also modulated hypothalamic expression of Mc4r and Bmp8b, which were increased and Mc3r, Pomc, Agrp and Ucp2, which were decreased. Finally, UAG, AG and combination treatments caused activation of c-Fos in POMC expressing neurons in the arcuate, substantiating a physiologic effect of these peptides on the central melanocortin system. Together, these results demonstrate that UAG can act directly to increase neuronal activity in the hypothalamus and is able to counteract AG-induced neuronal activity in the PVN and NTS. UAG also modulates expression of members of the melanocortin signaling system in the hypothalamus. In the absence of an effect on energy intake, these findings indicate that UAG could affect energy homeostasis by modulation of the central melanocortin system.
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Affiliation(s)
- Darko M. Stevanovic
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
- Institute of Medical Physiology, School of Medicine, University of Belgrade, Belgrade, Serbia
- * E-mail: (DS); (PJDD)
| | - Aldo Grefhorst
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Axel P. N. Themmen
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Vera Popovic
- Institute of Endocrinology, Diabetes and Diseases of Metabolism, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Joan Holstege
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Elize Haasdijk
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Vladimir Trajkovic
- Institute of Microbiology and Immunology, School of Medicine, University of Belgrade, Belgrade, Serbia
| | | | - Patric J. D. Delhanty
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
- * E-mail: (DS); (PJDD)
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Alsiö J, Rask-Andersen M, Chavan RA, Olszewski PK, Levine AS, Fredriksson R, Schiöth HB. Exposure to a high-fat high-sugar diet causes strong up-regulation of proopiomelanocortin and differentially affects dopamine D1 and D2 receptor gene expression in the brainstem of rats. Neurosci Lett 2014; 559:18-23. [DOI: 10.1016/j.neulet.2013.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 11/01/2013] [Accepted: 11/11/2013] [Indexed: 11/28/2022]
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11
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Eerola K, Nordlund W, Virtanen S, Dickens AM, Mattila M, Ruohonen ST, Chua SC, Wardlaw SL, Savontaus M, Savontaus E. Lentivirus-mediated α-melanocyte-stimulating hormone overexpression in the hypothalamus decreases diet induced obesity in mice. J Neuroendocrinol 2013; 25:1298-1307. [PMID: 24118213 DOI: 10.1111/jne.12109] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 09/20/2013] [Accepted: 09/21/2013] [Indexed: 11/29/2022]
Abstract
Melanocyte stimulating hormone (MSH) derived from the pro-hormone pro-opiomelanocortin (POMC) has potent effects on metabolism and feeding that lead to reduced body weight in the long-term. To determine the individual roles of POMC derived peptides and their sites of action, we created a method for the delivery of single MSH peptides using lentiviral vectors and studied the long-term anti-obesity effects of hypothalamic α-MSH overexpression in mice. An α-MSH lentivirus (LVi-α-MSH-EGFP) vector carrying the N'-terminal part of POMC and the α-MSH sequence was generated and shown to produce bioactive peptide in an in vitro melanin synthesis assay. Stereotaxis was used to deliver the LVi-α-MSH-EGFP or control LVi-EGFP vector to the arcuate nucleus (ARC) of the hypothalamus of male C57Bl/6N mice fed on a high-fat diet. The effects of 6-week-treatment on body weight, food intake, glucose tolerance and organ weights were determined. Additionally, a 14-day pairfeeding study was conducted to assess whether the weight decreasing effect of the LVi-α-MSH-EGFP treatment is dependent on decreased food intake. The 6-week LVi-α-MSH-EGFP treatment reduced weight gain (8.4 ± 0.4 g versus 12.3 ± 0.6 g; P < 0.05), which was statistically significant starting from 1 week after the injections. The weight of mesenteric fat was decreased and glucose tolerance was improved compared to LVi-EGFP treated mice. Food intake was decreased during the first week in the LVi-α-MSH-EGFP treated mice but subsequently increased to the level of LVi-EGFP treated mice. The LVi-EGFP injected control mice gained more weight even when pairfed to the level of food intake by LVi-α-MSH-EGFP treated mice. We demonstrate that gene transfer of α-MSH, a single peptide product of POMC, into the ARC of the hypothalamus, reduces obesity and improves glucose tolerance, and that factors other than decreased food intake also influence the weight decreasing effects of α-MSH overexpression in the ARC. Furthermore, viral MSH vectors delivered stereotaxically provide a novel tool for further exploration of chronic site-specific effects of POMC peptides.
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Affiliation(s)
- K Eerola
- Department of Pharmacology, Drug Development and Therapeutics, and Turku Center for Disease Modeling, University of Turku, Turku, Finland
- Turku Centre for Biotechnology, University of Turku, Turku, Finland
- FinPharma Doctoral Program, Drug Discovery Section, Turku, Finland
| | - W Nordlund
- Department of Pharmacology, Drug Development and Therapeutics, and Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - S Virtanen
- Department of Pharmacology, Drug Development and Therapeutics, and Turku Center for Disease Modeling, University of Turku, Turku, Finland
- Turku Centre for Biotechnology, University of Turku, Turku, Finland
| | - A M Dickens
- Department of Pharmacology, Drug Development and Therapeutics, and Turku Center for Disease Modeling, University of Turku, Turku, Finland
- Turku PET Centre, Medicity/PET Preclinical Imaging, University of Turku, Turku, Finland
| | - M Mattila
- Turku Centre for Biotechnology, University of Turku, Turku, Finland
- Medical Biochemistry and Genetics, University of Turku, Turku, Finland
| | - S T Ruohonen
- Department of Pharmacology, Drug Development and Therapeutics, and Turku Center for Disease Modeling, University of Turku, Turku, Finland
| | - S C Chua
- Albert Einstein College of Medicine, New York, NY, USA
| | - S L Wardlaw
- Department of Medicine, Columbia University College of Physicians & Surgeons, New York, NY, USA
| | - M Savontaus
- Turku Centre for Biotechnology, University of Turku, Turku, Finland
- Turku Heart Center, Turku University Hospital and University of Turku, Turku, Finland
| | - E Savontaus
- Department of Pharmacology, Drug Development and Therapeutics, and Turku Center for Disease Modeling, University of Turku, Turku, Finland
- Unit of Clinical Pharmacology, Turku University Hospital, Turku, Finland
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12
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Abstract
Obesity and its associated metabolic disorders are growing health concerns in the US and worldwide. In the US alone, more than two-thirds of the adult population is classified as either overweight or obese [1], highlighting the need to develop new, effective treatments for these conditions. Whereas the hormone oxytocin is well known for its peripheral effects on uterine contraction during parturition and milk ejection during lactation, release of oxytocin from somatodendrites and axonal terminals within the central nervous system (CNS) is implicated in both the formation of prosocial behaviors and in the control of energy balance. Recent findings demonstrate that chronic administration of oxytocin reduces food intake and body weight in diet-induced obese (DIO) and genetically obese rodents with impaired or defective leptin signaling. Importantly, chronic systemic administration of oxytocin out to 6 weeks recapitulates the effects of central administration on body weight loss in DIO rodents at doses that do not result in the development of tolerance. Furthermore, these effects are coupled with induction of Fos (a marker of neuronal activation) in hindbrain areas (e.g. dorsal vagal complex (DVC)) linked to the control of meal size and forebrain areas (e.g. hypothalamus, amygdala) linked to the regulation of food intake and body weight. This review assesses the potential central and peripheral targets by which oxytocin may inhibit body weight gain, its regulation by anorexigenic and orexigenic signals, and its potential use as a therapy that can circumvent leptin resistance and reverse the behavioral and metabolic abnormalities associated with DIO and genetically obese models.
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Affiliation(s)
- James E Blevins
- VA Puget Sound Health Care System, Office of Research and Development Medical Research Service, Department of Veterans Affairs Medical Center, Seattle, WA, 98108, USA,
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13
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Sugita M, Yamamoto K, Hirono C, Shiba Y. Information processing in brainstem bitter taste-relaying neurons defined by genetic tracing. Neuroscience 2013; 250:166-80. [PMID: 23850686 DOI: 10.1016/j.neuroscience.2013.06.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 06/07/2013] [Accepted: 06/17/2013] [Indexed: 11/19/2022]
Abstract
Bitter reception is mediated by taste receptor cells that coexpress multiple T2Rs, a family of G-protein-coupled receptors. However, it remains elusive how bitter taste information is translated in the brain into appropriate behavioral responses. Here we used a combination of genetic tracing and electrophysiological and immunohistochemical analyses in mice to functionally characterize the neurons in the solitary tract nuclei of the medulla, which receive input from mT2R5-expressing cells. The neurons defined by a transneuronal tracer originating from mT2R5-expressing cells receive glutamatergic synaptic input via the AMPA receptor. The satiety peptide cholecystokinin increases glutamatergic transmission, suggesting an interaction between information processing of taste and the homeostatic control of feeding. Nevertheless, the tracer-labeled neuron types are heterogeneous, and can be classified into catecholamine and pro-opiomelanocortin neurons. Our data reveal that the architectural solution in the first-order central relay that processes information from mT2R5-expressing cells uses unique ensembles of neurons with different neurotransmitters.
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Affiliation(s)
- M Sugita
- Department of Physiology and Oral Physiology, Institute of Biomedical & Health Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8553, Japan.
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14
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Blouet C, Schwartz GJ. Brainstem nutrient sensing in the nucleus of the solitary tract inhibits feeding. Cell Metab 2012; 16:579-87. [PMID: 23123165 PMCID: PMC3537851 DOI: 10.1016/j.cmet.2012.10.003] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Revised: 08/23/2012] [Accepted: 10/09/2012] [Indexed: 01/16/2023]
Abstract
Direct detection of circulating nutrients by the central nervous system has been implicated in the regulation of energy balance, and the mediobasal hypothalamus is considered as the primary sensing site mediating these effects. Neurons sensitive to energyrelated signals have also been identified outside the hypothalamus, particularly within the caudomedial nucleus of the solitary tract (cmNTS) in brainstem, but the consequences of direct cmNTS nutrient detection on energy balance remain poorly characterized. Here we determined the behavioral and metabolic consequences of direct L-leucine detection by the cmNTS and investigated the intracellular signaling and neurochemical pathways implicated in cmNTS L-leucine sensing in rats. Our results support the distributed nature of central nutrient detection, evidence a role for the cmNTS S6K1 pathway in the regulation of meal size and body weight, and suggest that the cmNTS integrates direct cmNTS nutrient detection with gut-derived, descending forebrain, and adiposity signals of energy availability to regulate food intake.
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Affiliation(s)
- Clemence Blouet
- Department of Medicine, Diabetes Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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15
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De Jonghe BC, Hayes MR, Zimmer DJ, Kanoski SE, Grill HJ, Bence KK. Food intake reductions and increases in energetic responses by hindbrain leptin and melanotan II are enhanced in mice with POMC-specific PTP1B deficiency. Am J Physiol Endocrinol Metab 2012; 303:E644-51. [PMID: 22761160 PMCID: PMC3468506 DOI: 10.1152/ajpendo.00009.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Leptin regulates energy balance through central circuits that control food intake and energy expenditure, including proopiomelanocortin (POMC) neurons. POMC neuron-specific deletion of protein tyrosine phosphatase 1B (PTP1B) (Ptpn1(loxP/loxP) POMC-Cre), a negative regulator of CNS leptin signaling, results in resistance to diet-induced obesity and improved peripheral leptin sensitivity in mice, thus establishing PTP1B as an important component of POMC neuron regulation of energy balance. POMC neurons are expressed in the pituitary, the arcuate nucleus of the hypothalamus (ARH), and the nucleus of the solitary tract (NTS) in the hindbrain, and it is unknown how each population might contribute to the phenotype of POMC-Ptp1b(-/-) mice. It is also unknown whether improved leptin sensitivity in POMC-Ptp1b(-/-) mice involves altered melanocortin receptor signaling. Therefore, we examined the effects of hindbrain administration (4th ventricle) of leptin (1.5, 3, and 6 μg) or the melanocortin 3/4R agonist melanotan II (0.1 and 0.2 nmol) in POMC-Ptp1b(-/-) (KO) and control PTP1B(fl/fl) (WT) mice on food intake, body weight, spontaneous physical activity (SPA), and core temperature (T(C)). The results show that KO mice were hypersensitive to hindbrain leptin- and MTII-induced food intake and body weight suppression and SPA compared with WT mice. Greater increases in leptin- but not MTII-induced T(C) were also observed in KO vs. WT animals. In addition, KO mice displayed elevated hindbrain and hypothalamic MC4R mRNA expression. These studies are the first to show that hindbrain administration of leptin or a melanocortin receptor agonist alters energy balance in mice likely via participation of hindbrain POMC neurons.
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MESH Headings
- Animals
- Appetite Depressants/administration & dosage
- Appetite Depressants/pharmacology
- Appetite Regulation/drug effects
- Dose-Response Relationship, Drug
- Energy Metabolism/drug effects
- Female
- Gene Expression Regulation/drug effects
- Injections, Intraventricular
- Leptin/administration & dosage
- Leptin/metabolism
- Male
- Mice
- Mice, Knockout
- Nerve Tissue Proteins/agonists
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neurons/drug effects
- Neurons/metabolism
- Organ Specificity
- Peptides, Cyclic/administration & dosage
- Peptides, Cyclic/pharmacology
- Pro-Opiomelanocortin/metabolism
- Protein Tyrosine Phosphatase, Non-Receptor Type 1/deficiency
- Protein Tyrosine Phosphatase, Non-Receptor Type 1/genetics
- Protein Tyrosine Phosphatase, Non-Receptor Type 1/metabolism
- RNA, Messenger/metabolism
- Receptor, Melanocortin, Type 3/agonists
- Receptor, Melanocortin, Type 4/agonists
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
- Rhombencephalon/drug effects
- Rhombencephalon/metabolism
- alpha-MSH/administration & dosage
- alpha-MSH/analogs & derivatives
- alpha-MSH/pharmacology
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Affiliation(s)
- Bart C De Jonghe
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia PA, USA
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16
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Weston-Green K, Huang XF, Deng C. Alterations to melanocortinergic, GABAergic and cannabinoid neurotransmission associated with olanzapine-induced weight gain. PLoS One 2012; 7:e33548. [PMID: 22438946 PMCID: PMC3306411 DOI: 10.1371/journal.pone.0033548] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 02/11/2012] [Indexed: 12/30/2022] Open
Abstract
Background/Aim Second generation antipsychotics (SGAs) are used to treat schizophrenia but can cause serious metabolic side-effects, such as obesity and diabetes. This study examined the effects of low to high doses of olanzapine on appetite/metabolic regulatory signals in the hypothalamus and brainstem to elucidate the mechanisms underlying olanzapine-induced obesity. Methodology/Results Levels of pro-opiomelanocortin (POMC), neuropeptide Y (NPY) and glutamic acid decarboxylase (GAD65, enzyme for GABA synthesis) mRNA expression, and cannabinoid CB1 receptor (CB1R) binding density (using [3H]SR-141716A) were examined in the arcuate nucleus (Arc) and dorsal vagal complex (DVC) of female Sprague Dawley rats following 0.25, 0.5, 1.0 or 2.0 mg/kg olanzapine or vehicle (3×/day, 14-days). Consistent with its weight gain liability, olanzapine significantly decreased anorexigenic POMC and increased orexigenic NPY mRNA expression in a dose-sensitive manner in the Arc. GAD65 mRNA expression increased and CB1R binding density decreased in the Arc and DVC. Alterations to neurotransmission signals in the brain significantly correlated with body weight and adiposity. The minimum dosage threshold required to induce weight gain in the rat was 0.5 mg/kg olanzapine. Conclusions Olanzapine-induced weight gain is associated with reduced appetite-inhibiting POMC and increased NPY. This study also supports a role for the CB1R and GABA in the mechanisms underlying weight gain side-effects, possibly by altering POMC transmission. Metabolic dysfunction can be modelled in the female rat using low, clinically-comparable olanzapine doses when administered in-line with the half-life of the drug.
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Affiliation(s)
- Katrina Weston-Green
- Centre for Translational Neuroscience, School of Health Sciences, University of Wollongong, Wollongong, Australia
- Schizophrenia Research Institute, Darlinghurst, Australia
| | - Xu-Feng Huang
- Centre for Translational Neuroscience, School of Health Sciences, University of Wollongong, Wollongong, Australia
- Schizophrenia Research Institute, Darlinghurst, Australia
| | - Chao Deng
- Centre for Translational Neuroscience, School of Health Sciences, University of Wollongong, Wollongong, Australia
- Schizophrenia Research Institute, Darlinghurst, Australia
- * E-mail:
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17
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Berglund ED, Vianna CR, Donato J, Kim MH, Chuang JC, Lee CE, Lauzon DA, Lin P, Brule LJ, Scott MM, Coppari R, Elmquist JK. Direct leptin action on POMC neurons regulates glucose homeostasis and hepatic insulin sensitivity in mice. J Clin Invest 2012; 122:1000-9. [PMID: 22326958 DOI: 10.1172/jci59816] [Citation(s) in RCA: 244] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 01/04/2012] [Indexed: 01/01/2023] Open
Abstract
Leptin action on its receptor (LEPR) stimulates energy expenditure and reduces food intake, thereby lowering body weight. One leptin-sensitive target cell mediating these effects on energy balance is the proopiomelano-cortin (POMC) neuron. Recent evidence suggests that the action of leptin on POMC neurons regulates glucose homeostasis independently of its effects on energy balance. Here, we have dissected the physiological impact of direct leptin action on POMC neurons using a mouse model in which endogenous LEPR expression was prevented by a LoxP-flanked transcription blocker (loxTB), but could be reactivated by Cre recombinase. Mice homozygous for the Lepr(loxTB) allele were obese and exhibited defects characteristic of LEPR deficiency. Reexpression of LEPR only in POMC neurons in the arcuate nucleus of the hypothalamus did not reduce food intake, but partially normalized energy expenditure and modestly reduced body weight. Despite the moderate effects on energy balance and independent of changes in body weight, restoring LEPR in POMC neurons normalized blood glucose and ameliorated hepatic insulin resistance, hyperglucagonemia, and dyslipidemia. Collectively, these results demonstrate that direct leptin action on POMC neurons does not reduce food intake, but is sufficient to normalize glucose and glucagon levels in mice otherwise lacking LEPR.
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Affiliation(s)
- Eric D Berglund
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical School, Dallas, Texas 75390-9051, USA
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18
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Abstract
The hedonic properties of food can stimulate feeding behaviour even when energy requirements have been met, contributing to weight gain and obesity. Similarly, the hedonic effects of drugs of abuse can motivate their excessive intake, culminating in addiction. Common brain substrates regulate the hedonic properties of palatable food and addictive drugs, and recent reports suggest that excessive consumption of food or drugs of abuse induces similar neuroadaptive responses in brain reward circuitries. Here, we review evidence suggesting that obesity and drug addiction may share common molecular, cellular and systems-level mechanisms.
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19
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Resch JM, Boisvert JP, Hourigan AE, Mueller CR, Yi SS, Choi S. Stimulation of the hypothalamic ventromedial nuclei by pituitary adenylate cyclase-activating polypeptide induces hypophagia and thermogenesis. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1625-34. [PMID: 21957159 DOI: 10.1152/ajpregu.00334.2011] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Numerous studies have demonstrated that the hypothalamic ventromedial nuclei (VMN) regulate energy homeostasis by integrating and utilizing behavioral and metabolic mechanisms. The VMN heavily express pituitary adenylate cyclase-activating polypeptide (PACAP) type I receptors (PAC1R). Despite the receptor distribution, most PACAP experiments investigating affects on feeding have focused on intracerebroventricular administration or global knockout mice. To identify the specific contribution of PACAP signaling in the VMN, we injected PACAP directly into the VMN and measured feeding behavior and indices of energy expenditure. Following an acute injection of PACAP, nocturnal food intake was significantly reduced for 6 h after injections without evidence of malaise. In addition, PACAP-induced suppression of feeding also occurred following an overnight fast and could be blocked by a specific PAC1R antagonist. Metabolically, VMN-specific injections of PACAP significantly increased both core body temperature and spontaneous locomotor activity with a concurrent increase in brown adipose uncoupling protein 1 mRNA expression. To determine which signaling pathways were responsive to PACAP administration into the VMN, we measured mRNA expression of well-characterized hypothalamic neuropeptide regulators of feeding. One hour after PACAP administration, expression of pro-opiomelanocortin mRNA was significantly increased in the arcuate nuclei (ARC), with no changes in neuropeptide Y and agouti-related polypeptide mRNA levels. This suggests that PAC1R expressing VMN neurons projecting to pro-opiomelanocortin neurons contribute to hypophagia by involving melanocortin signaling. While the VMN also abundantly express PACAP protein, the present study demonstrates that PACAP input to the VMN can influence the control of energy homeostasis.
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Affiliation(s)
- Jon M Resch
- Department of Biomedical Sciences, Marquette University, Milwaukee, Wisconsin, USA
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20
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De Jonghe BC, Hayes MR, Bence KK. Melanocortin control of energy balance: evidence from rodent models. Cell Mol Life Sci 2011; 68:2569-88. [PMID: 21553232 PMCID: PMC3135719 DOI: 10.1007/s00018-011-0707-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 04/19/2011] [Accepted: 04/20/2011] [Indexed: 01/18/2023]
Abstract
Regulation of energy balance is extremely complex, and involves multiple systems of hormones, neurotransmitters, receptors, and intracellular signals. As data have accumulated over the last two decades, the CNS melanocortin system is now identified as a prominent integrative network of energy balance controls in the mammalian brain. Here, we will review findings from rat and mouse models, which have provided an important framework in which to study melanocortin function. Perhaps most importantly, this review attempts for the first time to summarize recent advances in our understanding of the intracellular signaling pathways thought to mediate the action of melanocortin neurons and peptides in control of longterm energy balance. Special attention will be paid to the roles of MC4R/MC3R, as well as downstream neurotransmitters within forebrain and hindbrain structures that illustrate the distributed control of melanocortin signaling in energy balance. In addition, distinctions and controversy between rodent species will be discussed.
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Affiliation(s)
- Bart C. De Jonghe
- Dept. of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104
| | - Matthew R. Hayes
- Dept. of Psychiatry, School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104
| | - Kendra K. Bence
- Dept. of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104
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