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Moore JM, Bell EL, Hughes RO, Garfield AS. ABC transporters: human disease and pharmacotherapeutic potential. Trends Mol Med 2023; 29:152-172. [PMID: 36503994 DOI: 10.1016/j.molmed.2022.11.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/24/2022] [Accepted: 11/01/2022] [Indexed: 12/12/2022]
Abstract
Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are a 48-member superfamily of membrane proteins that actively transport a variety of biological substrates across lipid membranes. Their functional diversity defines an expansive involvement in myriad aspects of human biology. At least 21 ABC transporters underlie rare monogenic disorders, with even more implicated in the predisposition to and symptomology of common and complex diseases. Such broad (patho)physiological relevance places this class of proteins at the intersection of disease causation and therapeutic potential, underlining them as promising targets for drug discovery, as exemplified by the transformative CFTR (ABCC7) modulator therapies for cystic fibrosis. This review will explore the growing relevance of ABC transporters to human disease and their potential as small-molecule drug targets.
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Georgescu T, Lyons D, Doslikova B, Garcia AP, Marston O, Burke LK, Chianese R, Lam BYH, Yeo GSH, Rochford JJ, Garfield AS, Heisler LK. Neurochemical Characterization of Brainstem Pro-Opiomelanocortin Cells. Endocrinology 2020; 161:bqaa032. [PMID: 32166324 PMCID: PMC7102873 DOI: 10.1210/endocr/bqaa032] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 03/10/2020] [Indexed: 02/08/2023]
Abstract
Genetic research has revealed pro-opiomelanocortin (POMC) to be a fundamental regulator of energy balance and body weight in mammals. Within the brain, POMC is primarily expressed in the arcuate nucleus of the hypothalamus (ARC), while a smaller population exists in the brainstem nucleus of the solitary tract (POMCNTS). We performed a neurochemical characterization of this understudied population of POMC cells using transgenic mice expressing green fluorescent protein (eGFP) under the control of a POMC promoter/enhancer (PomceGFP). Expression of endogenous Pomc mRNA in the nucleus of the solitary tract (NTS) PomceGFP cells was confirmed using fluorescence-activating cell sorting (FACS) followed by quantitative PCR. In situ hybridization histochemistry of endogenous Pomc mRNA and immunohistochemical analysis of eGFP revealed that POMC is primarily localized within the caudal NTS. Neurochemical analysis indicated that POMCNTS is not co-expressed with tyrosine hydroxylase (TH), glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), brain-derived neurotrophic factor (BDNF), nesfatin, nitric oxide synthase 1 (nNOS), seipin, or choline acetyltransferase (ChAT) cells, whereas 100% of POMCNTS is co-expressed with transcription factor paired-like homeobox2b (Phox2b). We observed that 20% of POMCNTS cells express receptors for adipocyte hormone leptin (LepRbs) using a PomceGFP:LepRbCre:tdTOM double-reporter line. Elevations in endogenous or exogenous leptin levels increased the in vivo activity (c-FOS) of a small subset of POMCNTS cells. Using ex vivo slice electrophysiology, we observed that this effect of leptin on POMCNTS cell activity is postsynaptic. These findings reveal that a subset of POMCNTS cells are responsive to both changes in energy status and the adipocyte hormone leptin, findings of relevance to the neurobiology of obesity.
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Affiliation(s)
- Teodora Georgescu
- Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen, UK
- Department of Pharmacology, University of Cambridge, Cambridge, UK
- Centre for Neuroendocrinology & Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - David Lyons
- Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen, UK
| | | | - Ana Paula Garcia
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Oliver Marston
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Luke K Burke
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | | | - Brian Y H Lam
- MRC Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, UK
| | - Giles S H Yeo
- MRC Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, UK
| | | | | | - Lora K Heisler
- Rowett Institute, University of Aberdeen, Foresterhill, Aberdeen, UK
- Department of Pharmacology, University of Cambridge, Cambridge, UK
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Eneli I, Xu J, Webster M, McCagg A, Van Der Ploeg L, Garfield AS, Estrada E. Tracing the effect of the melanocortin-4 receptor pathway in obesity: study design and methodology of the TEMPO registry. Appl Clin Genet 2019; 12:87-93. [PMID: 31239751 PMCID: PMC6556479 DOI: 10.2147/tacg.s199092] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 05/08/2019] [Indexed: 12/15/2022]
Abstract
Purpose: The hypothalamic melanocortin-4 receptor (MC4R) pathway, a component of the central melanocortin pathway, regulates energy balance and satiety. Rare genetic disorders of obesity may be characterized by impaired MC4R pathway signaling, which results in early-onset severe obesity and insatiable hunger (hyperphagia). The TEMPO registry (NCT03479437) is a voluntary, prospective, open-ended registry of individuals with rare genetic disorders of obesity due to mutations in genes within the MC4R pathway who have early-onset severe obesity. The objective of the TEMPO registry is to evaluate the burden of rare genetic disorders of obesity on individuals, their parents/caregivers, health care providers, and the health care system. Patients and methods: Individuals with rare genetic disorders of obesity (adults aged ≥18 years and children and adolescents aged from 2 to 17 years) will be referred by their health care providers or by a genetic screening study. Individuals must meet age- and sex-specific body mass index values that define the clinical criteria for severe obesity and carry selected variants in MC4R or in one of several genes upstream or downstream of the MC4R. Online surveys will be completed by the individual, parent/caregiver, and health care provider at baseline and annually thereafter and will collect data on demographics, results of genetic testing, medical/family history, disease characteristics, resource utilization, eating habits/hunger episodes, social and emotional impacts, and interest in future clinical trial participation. Conclusions: The TEMPO registry will provide insights into the overall course and disease burden for individuals with rare genetic disorders of obesity. Health care providers may use this resource to improve the identification, diagnosis, and treatment of individuals with rare forms of genetic obesity.
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Affiliation(s)
- Ihuoma Eneli
- Center for Healthy Weight and Nutrition, Nationwide Children's Hospital, Columbus, OH, USA.,Department of Pediatrics, The Ohio State University, Columbus, OH, USA
| | - Jinyu Xu
- Center for Healthy Weight and Nutrition, Nationwide Children's Hospital, Columbus, OH, USA
| | - Matthew Webster
- Department of Medical Communications, Rhythm Pharmaceuticals, Inc, Boston, MA, USA
| | - Amy McCagg
- Department of Medical Communications, Rhythm Pharmaceuticals, Inc, Boston, MA, USA
| | - Lex Van Der Ploeg
- Department of Medical Communications, Rhythm Pharmaceuticals, Inc, Boston, MA, USA
| | - Alastair S Garfield
- Department of Medical Communications, Rhythm Pharmaceuticals, Inc, Boston, MA, USA
| | - Elizabeth Estrada
- Department of Pediatric Endocrinology, University of North Carolina, Chapel Hill, NC, USA
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Sharma S, Garfield AS, Shah B, Kleyn P, Ichetovkin I, Moeller IH, Mowrey WR, Van der Ploeg LHT. Current Mechanistic and Pharmacodynamic Understanding of Melanocortin-4 Receptor Activation. Molecules 2019; 24:molecules24101892. [PMID: 31100979 PMCID: PMC6572030 DOI: 10.3390/molecules24101892] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 05/15/2019] [Accepted: 05/15/2019] [Indexed: 12/20/2022] Open
Abstract
In this work we summarize our understanding of melanocortin 4 receptor (MC4R) pathway activation, aiming to define a safe and effective therapeutic targeting strategy for the MC4R. Delineation of cellular MC4R pathways has provided evidence for distinct MC4R signaling events characterized by unique receptor activation kinetics. While these studies remain narrow in scope, and have largely been explored with peptidic agonists, the results provide a possible correlation between distinct ligand groups and differential MC4R activation kinetics. In addition, when a set of small-molecule and peptide MC4R agonists are compared, evidence of biased signaling has been reported. The results of such mechanistic studies are discussed.
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Affiliation(s)
| | | | - Bhavik Shah
- Rhythm Pharmaceuticals, Boston, MA 02116, USA.
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Li MM, Madara JC, Steger JS, Krashes MJ, Balthasar N, Campbell JN, Resch JM, Conley NJ, Garfield AS, Lowell BB. The Paraventricular Hypothalamus Regulates Satiety and Prevents Obesity via Two Genetically Distinct Circuits. Neuron 2019; 102:653-667.e6. [PMID: 30879785 DOI: 10.1016/j.neuron.2019.02.028] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 02/02/2019] [Accepted: 02/15/2019] [Indexed: 12/15/2022]
Abstract
SIM1-expressing paraventricular hypothalamus (PVH) neurons are key regulators of energy balance. Within the PVHSIM1 population, melanocortin-4 receptor-expressing (PVHMC4R) neurons are known to regulate satiety and bodyweight, yet they account for only half of PVHSIM1 neuron-mediated regulation. Here we report that PVH prodynorphin-expressing (PVHPDYN) neurons, which notably lack MC4Rs, function independently and additively with PVHMC4R neurons to account for the totality of PVHSIM1 neuron-mediated satiety. Moreover, PVHPDYN neurons are necessary for prevention of obesity in an independent but equipotent manner to PVHMC4R neurons. While PVHPDYN and PVHMC4R neurons both project to the parabrachial complex (PB), they synaptically engage distinct efferent nodes, the pre-locus coeruleus (pLC), and central lateral parabrachial nucleus (cLPBN), respectively. PB-projecting PVHPDYN neurons, like PVHMC4R neurons, receive input from interoceptive ARCAgRP neurons, respond to caloric state, and are sufficient and necessary to control food intake. This expands the CNS satiety circuitry to include two non-overlapping PVH to hindbrain circuits.
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Affiliation(s)
- Monica M Li
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Joseph C Madara
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Jennifer S Steger
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Michael J Krashes
- Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Nina Balthasar
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - John N Campbell
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Jon M Resch
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Nicholas J Conley
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Alastair S Garfield
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA; Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA; Program in Neuroscience, Harvard Medical School, Boston, MA 02215, USA.
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Ayers KL, Glicksberg BS, Garfield AS, Longerich S, White JA, Yang P, Du L, Chittenden TW, Gulcher JR, Roy S, Fiedorek F, Gottesdiener K, Cohen S, North KE, Schadt EE, Li SD, Chen R, Van der Ploeg LHT. Melanocortin 4 Receptor Pathway Dysfunction in Obesity: Patient Stratification Aimed at MC4R Agonist Treatment. J Clin Endocrinol Metab 2018; 103:2601-2612. [PMID: 29726959 PMCID: PMC7263790 DOI: 10.1210/jc.2018-00258] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 04/27/2018] [Indexed: 01/03/2023]
Abstract
CONTEXT The hypothalamic melanocortin 4 receptor (MC4R) pathway serves a critical role in regulating body weight. Loss of function (LoF) mutations in the MC4R pathway, including mutations in the pro-opiomelanocortin (POMC), prohormone convertase 1 (PCSK1), leptin receptor (LEPR), or MC4R genes, have been shown to cause early-onset severe obesity. METHODS Through a comprehensive epidemiological analysis of known and predicted LoF variants in the POMC, PCSK1, and LEPR genes, we sought to estimate the number of US individuals with biallelic MC4R pathway LoF variants. RESULTS We predict ~650 α-melanocyte-stimulating hormone (MSH)/POMC, 8500 PCSK1, and 3600 LEPR homozygous and compound heterozygous individuals in the United States, cumulatively enumerating >12,800 MC4R pathway-deficient obese patients. Few of these variants have been genetically diagnosed to date. These estimates increase when we include a small subset of less rare variants: β-MSH/POMC,PCSK1 N221D, and a PCSK1 LoF variant (T640A). To further define the MC4R pathway and its potential impact on obesity, we tested associations between body mass index (BMI) and LoF mutation burden in the POMC, PCSK1, and LEPR genes in various populations. We show that the cumulative allele burden in individuals with two or more LoF alleles in one or more genes in the MC4R pathway are predisposed to a higher BMI than noncarriers or heterozygous LoF carriers with a defect in only one gene. CONCLUSIONS Our analysis represents a genetically rationalized study of the hypothalamic MC4R pathway aimed at genetic patient stratification to determine which obese subpopulations should be studied to elucidate MC4R agonist (e.g., setmelanotide) treatment responsiveness.
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Affiliation(s)
- Kristin L Ayers
- Department of Genetics and Genomic Sciences, Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York
- Sema4, Stamford, Connecticut
| | - Benjamin S Glicksberg
- Department of Genetics and Genomic Sciences, Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York
| | | | | | | | | | - Lei Du
- WuXiNextCode, Cambridge, Massachusetts
| | | | | | - Sophie Roy
- Rhythm Pharmaceuticals, Boston, Massachusetts
| | | | | | | | - Kari E North
- University of North Carolina, Chapel Hill, North Carolina
| | - Eric E Schadt
- Department of Genetics and Genomic Sciences, Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York
- Sema4, Stamford, Connecticut
| | - Shuyu D Li
- Department of Genetics and Genomic Sciences, Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York
- Sema4, Stamford, Connecticut
- Correspondence and Reprint Requests: Shuyu D. Li, PhD, or Rong Chen, PhD, Icahn School of Medicine at Mount Sinai, 1255 5th Avenue, New York, New York 10029. E-mail: or; or Lex H. T. Van der Ploeg, PhD, Rhythm Pharmaceuticals, 500 Boylston Street, Boston, Massachusetts 02116. E-mail:
| | - Rong Chen
- Department of Genetics and Genomic Sciences, Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, New York
- Sema4, Stamford, Connecticut
- Correspondence and Reprint Requests: Shuyu D. Li, PhD, or Rong Chen, PhD, Icahn School of Medicine at Mount Sinai, 1255 5th Avenue, New York, New York 10029. E-mail: or; or Lex H. T. Van der Ploeg, PhD, Rhythm Pharmaceuticals, 500 Boylston Street, Boston, Massachusetts 02116. E-mail:
| | - Lex H T Van der Ploeg
- Rhythm Pharmaceuticals, Boston, Massachusetts
- Correspondence and Reprint Requests: Shuyu D. Li, PhD, or Rong Chen, PhD, Icahn School of Medicine at Mount Sinai, 1255 5th Avenue, New York, New York 10029. E-mail: or; or Lex H. T. Van der Ploeg, PhD, Rhythm Pharmaceuticals, 500 Boylston Street, Boston, Massachusetts 02116. E-mail:
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7
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Garfield AS, Davies JR, Burke LK, Furby HV, Wilkinson LS, Heisler LK, Isles AR. Increased alternate splicing of Htr2c in a mouse model for Prader-Willi syndrome leads disruption of 5HT 2C receptor mediated appetite. Mol Brain 2016; 9:95. [PMID: 27931246 PMCID: PMC5144496 DOI: 10.1186/s13041-016-0277-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 11/30/2016] [Indexed: 12/21/2022] Open
Abstract
Alternate splicing of serotonin (5-hydroxytryptamine; 5-HT) 2C receptor (5-HT2CR) pre-RNA is negatively regulated by the small nucleolar RNA, Snord115, loss of which is observed in nearly all individuals with Prader-Willi Syndrome (PWS), a multigenic disorder characterised by hyperphagia and obesity. Given the role of the 5-HT2CR in the regulation of ingestive behaviour we investigated the pathophysiological implications of Snord115 deficiency on 5-HT2CR regulated appetite in a genotypically relevant PWS mouse model (PWS-IC). Specifically, we demonstrate that loss of Snord115 expression is associated with increased levels of hypothalamic truncated 5-HT2CR pre-mRNA. The 5-HT2CR promotes appetite suppression via engagement of the central melanocortin system. Pro-opiomelancortin (Pomc) mRNA levels within the arcuate nucleus of the hypothalamus (ARC) were reduced in PWS-IC mice. We then went on to assess the functional consequences of these molecular changes, demonstrating that PWS-IC mice are unresponsive to an anorectic doses of a 5-HT2CR agonist and that this is associated with attenuated activation of POMC neurons within the ARC. These data provide new insight into the significance of Htr2c pre-mRNA processing to the physiological regulation of appetite and potentially the pathological manifestation of hyperphagia in PWS. Furthermore, these findings have translational relevance for individuals with PWS who may seek to control appetite with another 5-HT2CR agonist, the new obesity treatment lorcaserin.
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Affiliation(s)
- Alastair S Garfield
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.,Present address: Cardiovascular and Metabolic Disease, Pfizer, Cambridge, MA, 02139, USA
| | - Jennifer R Davies
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine and Pscyhology, Cardiff University, Cardiff, UK
| | - Luke K Burke
- Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Hannah V Furby
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine and Pscyhology, Cardiff University, Cardiff, UK
| | - Lawrence S Wilkinson
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine and Pscyhology, Cardiff University, Cardiff, UK
| | - Lora K Heisler
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Anthony R Isles
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine and Pscyhology, Cardiff University, Cardiff, UK.
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Martin-Gronert MS, Stocker CJ, Wargent ET, Cripps RL, Garfield AS, Jovanovic Z, D'Agostino G, Yeo GSH, Cawthorne MA, Arch JRS, Heisler LK, Ozanne SE. 5-HT2A and 5-HT2C receptors as hypothalamic targets of developmental programming in male rats. Development 2016. [DOI: 10.1242/dev.138396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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9
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Burke LK, Doslikova B, D'Agostino G, Greenwald-Yarnell M, Georgescu T, Chianese R, Martinez de Morentin PB, Ogunnowo-Bada E, Cansell C, Valencia-Torres L, Garfield AS, Apergis-Schoute J, Lam DD, Speakman JR, Rubinstein M, Low MJ, Rochford JJ, Myers MG, Evans ML, Heisler LK. Sex difference in physical activity, energy expenditure and obesity driven by a subpopulation of hypothalamic POMC neurons. Mol Metab 2016; 5:245-252. [PMID: 26977396 PMCID: PMC4770275 DOI: 10.1016/j.molmet.2016.01.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Obesity is one of the primary healthcare challenges of the 21st century. Signals relaying information regarding energy needs are integrated within the brain to influence body weight. Central among these integration nodes are the brain pro-opiomelanocortin (POMC) peptides, perturbations of which disrupt energy balance and promote severe obesity. However, POMC neurons are neurochemically diverse and the crucial source of POMC peptides that regulate energy homeostasis and body weight remains to be fully clarified. METHODS Given that a 5-hydroxytryptamine 2c receptor (5-HT2CR) agonist is a current obesity medication and 5-HT2CR agonist's effects on appetite are primarily mediated via POMC neurons, we hypothesized that a critical source of POMC regulating food intake and body weight is specifically synthesized in cells containing 5-HT2CRs. To exclusively manipulate Pomc synthesis only within 5-HT2CR containing cells, we generated a novel 5-HT 2C R (CRE) mouse line and intercrossed it with Cre recombinase-dependent and hypothalamic specific reactivatable Pomc (NEO) mice to restrict Pomc synthesis to the subset of hypothalamic cells containing 5-HT2CRs. This provided a means to clarify the specific contribution of a defined subgroup of POMC peptides in energy balance and body weight. RESULTS Here we transform genetically programed obese and hyperinsulinemic male mice lacking hypothalamic Pomc with increased appetite, reduced physical activity and compromised brown adipose tissue (BAT) into lean, healthy mice via targeted restoration of Pomc function only within 5-HT2CR expressing cells. Remarkably, the same metabolic transformation does not occur in females, who despite corrected feeding behavior and normalized insulin levels remain physically inactive, have lower energy expenditure, compromised BAT and develop obesity. CONCLUSIONS These data provide support for the functional heterogeneity of hypothalamic POMC neurons, revealing that Pomc expression within 5-HT2CR expressing neurons is sufficient to regulate energy intake and insulin sensitivity in male and female mice. However, an unexpected sex difference in the function of this subset of POMC neurons was identified with regard to energy expenditure. We reveal that a large sex difference in physical activity, energy expenditure and the development of obesity is driven by this subpopulation, which constitutes approximately 40% of all POMC neurons in the hypothalamic arcuate nucleus. This may have broad implications for strategies utilized to combat obesity, which at present largely ignore the sex of the obese individual.
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Affiliation(s)
- Luke K Burke
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK; Department of Medicine and Institute of Metabolic Science, University of Cambridge, Wellcome Trust/Medical Research Council, Cambridge, UK; Department of Pharmacology, University of Cambridge, Cambridge, UK
| | | | - Giuseppe D'Agostino
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK; Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Megan Greenwald-Yarnell
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Teodora Georgescu
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Raffaella Chianese
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | | | - Emmanuel Ogunnowo-Bada
- Department of Medicine and Institute of Metabolic Science, University of Cambridge, Wellcome Trust/Medical Research Council, Cambridge, UK
| | - Celine Cansell
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Lourdes Valencia-Torres
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK; Department of Pharmacology, University of Cambridge, Cambridge, UK
| | | | | | - Daniel D Lam
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - John R Speakman
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK; State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Marcelo Rubinstein
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, 1428, Buenos Aires, Argentina
| | - Malcolm J Low
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Justin J Rochford
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK
| | - Martin G Myers
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Mark L Evans
- Department of Medicine and Institute of Metabolic Science, University of Cambridge, Wellcome Trust/Medical Research Council, Cambridge, UK.
| | - Lora K Heisler
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, UK.
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10
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Martin-Gronert MS, Stocker CJ, Wargent ET, Cripps RL, Garfield AS, Jovanovic Z, D'Agostino G, Yeo GSH, Cawthorne MA, Arch JRS, Heisler LK, Ozanne SE. 5-HT2A and 5-HT2C receptors as hypothalamic targets of developmental programming in male rats. Dis Model Mech 2016; 9:401-12. [PMID: 26769798 PMCID: PMC4852506 DOI: 10.1242/dmm.023903] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 01/07/2016] [Indexed: 12/11/2022] Open
Abstract
Although obesity is a global epidemic, the physiological mechanisms involved are not well understood. Recent advances reveal that susceptibility to obesity can be programmed by maternal and neonatal nutrition. Specifically, a maternal low-protein diet during pregnancy causes decreased intrauterine growth, rapid postnatal catch-up growth and an increased risk for diet-induced obesity. Given that the synthesis of the neurotransmitter 5-hydroxytryptamine (5-HT) is nutritionally regulated and 5-HT is a trophic factor, we hypothesised that maternal diet influences fetal 5-HT exposure, which then influences development of the central appetite network and the subsequent efficacy of 5-HT to control energy balance in later life. Consistent with our hypothesis, pregnant rats fed a low-protein diet exhibited elevated serum levels of 5-HT, which was also evident in the placenta and fetal brains at embryonic day 16.5. This increase was associated with reduced levels of 5-HT2CR, the primary 5-HT receptor influencing appetite, in the fetal, neonatal and adult hypothalamus. As expected, a reduction of 5-HT2CR was associated with impaired sensitivity to 5-HT-mediated appetite suppression in adulthood. 5-HT primarily achieves effects on appetite by 5-HT2CR stimulation of pro-opiomelanocortin (POMC) peptides within the arcuate nucleus of the hypothalamus (ARC). We show that 5-HT2ARs are also anatomically positioned to influence the activity of ARC POMC neurons and that mRNA encoding 5-HT2AR is increased in the hypothalamus ofin uterogrowth-restricted offspring that underwent rapid postnatal catch-up growth. Furthermore, these animals at 3 months of age are more sensitive to appetite suppression induced by 5-HT2AR agonists. These findings not only reveal a 5-HT-mediated mechanism underlying the programming of susceptibility to obesity, but also provide a promising means to correct it, by treatment with a 5-HT2AR agonist.
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Affiliation(s)
- Malgorzata S Martin-Gronert
- University of Cambridge, Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Claire J Stocker
- Clore Laboratory, Buckingham Institute for Translational Medicine, University of Buckingham, Hunter Street, Buckingham MK18 1EG, UK
| | - Edward T Wargent
- Clore Laboratory, Buckingham Institute for Translational Medicine, University of Buckingham, Hunter Street, Buckingham MK18 1EG, UK
| | - Roselle L Cripps
- University of Cambridge, Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | | | - Zorica Jovanovic
- University of Cambridge, Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | | | - Giles S H Yeo
- University of Cambridge, Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Michael A Cawthorne
- Clore Laboratory, Buckingham Institute for Translational Medicine, University of Buckingham, Hunter Street, Buckingham MK18 1EG, UK
| | - Jonathan R S Arch
- Clore Laboratory, Buckingham Institute for Translational Medicine, University of Buckingham, Hunter Street, Buckingham MK18 1EG, UK
| | - Lora K Heisler
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
| | - Susan E Ozanne
- University of Cambridge, Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
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11
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Geerling JC, Kim M, Mahoney CE, Abbott SBG, Agostinelli LJ, Garfield AS, Krashes MJ, Lowell BB, Scammell TE. Genetic identity of thermosensory relay neurons in the lateral parabrachial nucleus. Am J Physiol Regul Integr Comp Physiol 2015; 310:R41-54. [PMID: 26491097 DOI: 10.1152/ajpregu.00094.2015] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 10/02/2015] [Indexed: 12/31/2022]
Abstract
The parabrachial nucleus is important for thermoregulation because it relays skin temperature information from the spinal cord to the hypothalamus. Prior work in rats localized thermosensory relay neurons to its lateral subdivision (LPB), but the genetic and neurochemical identity of these neurons remains unknown. To determine the identity of LPB thermosensory neurons, we exposed mice to a warm (36°C) or cool (4°C) ambient temperature. Each condition activated neurons in distinct LPB subregions that receive input from the spinal cord. Most c-Fos+ neurons in these LPB subregions expressed the transcription factor marker FoxP2. Consistent with prior evidence that LPB thermosensory relay neurons are glutamatergic, all FoxP2+ neurons in these subregions colocalized with green fluorescent protein (GFP) in reporter mice for Vglut2, but not for Vgat. Prodynorphin (Pdyn)-expressing neurons were identified using a GFP reporter mouse and formed a caudal subset of LPB FoxP2+ neurons, primarily in the dorsal lateral subnucleus (PBdL). Warm exposure activated many FoxP2+ neurons within PBdL. Half of the c-Fos+ neurons in PBdL were Pdyn+, and most of these project into the preoptic area. Cool exposure activated a separate FoxP2+ cluster of neurons in the far-rostral LPB, which we named the rostral-to-external lateral subnucleus (PBreL). These findings improve our understanding of LPB organization and reveal that Pdyn-IRES-Cre mice provide genetic access to warm-activated, FoxP2+ glutamatergic neurons in PBdL, many of which project to the hypothalamus.
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Affiliation(s)
- Joel C Geerling
- Department of Neurology, Beth Israel Deaconess Medical Center; Harvard Medical School, Boston, Massachusetts;
| | - Minjee Kim
- Department of Neurology, Beth Israel Deaconess Medical Center; Harvard Medical School, Boston, Massachusetts
| | - Carrie E Mahoney
- Department of Neurology, Beth Israel Deaconess Medical Center; Harvard Medical School, Boston, Massachusetts
| | - Stephen B G Abbott
- Department of Neurology, Beth Israel Deaconess Medical Center; Harvard Medical School, Boston, Massachusetts
| | - Lindsay J Agostinelli
- Department of Neurology, Beth Israel Deaconess Medical Center; Harvard Medical School, Boston, Massachusetts
| | - Alastair S Garfield
- Division of Endocrinology, Department of Medicine, Beth Israel Deaconess Medical Center; Harvard Medical School, Boston, Massachusetts; Centre for Integrative Physiology, University of Edinburgh, Edinburgh, Scotland
| | - Michael J Krashes
- Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland; and National Institute on Drug Abuse, National Institutes of Health, Bethesda, Maryland
| | - Bradford B Lowell
- Division of Endocrinology, Department of Medicine, Beth Israel Deaconess Medical Center; Harvard Medical School, Boston, Massachusetts
| | - Thomas E Scammell
- Department of Neurology, Beth Israel Deaconess Medical Center; Harvard Medical School, Boston, Massachusetts
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12
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Davies JR, Humby T, Dwyer DM, Garfield AS, Furby H, Wilkinson LS, Wells T, Isles AR. Calorie seeking, but not hedonic response, contributes to hyperphagia in a mouse model for Prader-Willi syndrome. Eur J Neurosci 2015; 42:2105-13. [PMID: 26040449 PMCID: PMC4949663 DOI: 10.1111/ejn.12972] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 05/29/2015] [Accepted: 05/29/2015] [Indexed: 12/25/2022]
Abstract
Prader–Willi syndrome (PWS) is a neurodevelopmental disorder caused by deletion or inactivation of paternally expressed imprinted genes on human chromosome 15q11‐q13, the most recognised feature of which is hyperphagia. This is thought to arise as a consequence of abnormalities in both the physiological drive for food and the rewarding properties of food. Although a number of mouse models for PWS exist, the underlying variables dictating maladaptive feeding remain unknown. Here, feeding behaviour in a mouse model in which the imprinting centre (IC) of the syntenic PWS interval has been deleted (PWSICdel mice) is characterised. It is demonstrated that PWSICdel mice show hyperghrelinaemia and increased consumption of food both following overnight fasting and when made more palatable with sucrose. However, hyperphagia in PWSICdel mice was not accompanied by any changes in reactivity to the hedonic properties of palatable food (sucrose or saccharin), as measured by lick‐cluster size. Nevertheless, overall consumption by PWSICdel mice for non‐caloric saccharin in the licking test was significantly reduced. Combined with converging findings from a continuous reinforcement schedule, these data indicate that PWSICdel mice show a marked heightened sensitivity to the calorific value of food. Overall, these data indicate that any impact of the rewarding properties of food on the hyperphagia seen in PWSICdel mice is driven primarily by calorie content and is unlikely to involve hedonic processes. This has important implications for understanding the neural systems underlying the feeding phenotype of PWS and the contribution of imprinted genes to abnormal feeding behaviour more generally.
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Affiliation(s)
- Jennifer R Davies
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Cardiff University, Hadyn Ellis Building, Cardiff, CF24 4HQ, UK.,School of Medicine, Cardiff University, Cardiff, UK
| | - Trevor Humby
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Cardiff University, Hadyn Ellis Building, Cardiff, CF24 4HQ, UK.,School of Psychology, Cardiff University, Cardiff, UK
| | - Dominic M Dwyer
- School of Psychology, Cardiff University, Cardiff, UK.,School of Psychology, University of New South Wales, Sydney, NSW, Australia
| | | | - Hannah Furby
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Cardiff University, Hadyn Ellis Building, Cardiff, CF24 4HQ, UK.,School of Medicine, Cardiff University, Cardiff, UK.,School of Biosciences, Cardiff University, Cardiff, UK
| | - Lawrence S Wilkinson
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Cardiff University, Hadyn Ellis Building, Cardiff, CF24 4HQ, UK.,School of Medicine, Cardiff University, Cardiff, UK.,School of Psychology, Cardiff University, Cardiff, UK
| | - Timothy Wells
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Anthony R Isles
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Cardiff University, Hadyn Ellis Building, Cardiff, CF24 4HQ, UK.,School of Medicine, Cardiff University, Cardiff, UK
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13
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Madon-Simon M, Cowley M, Garfield AS, Moorwood K, Bauer SR, Ward A. Antagonistic roles in fetal development and adult physiology for the oppositely imprinted Grb10 and Dlk1 genes. BMC Biol 2014; 12:771. [PMID: 25551289 PMCID: PMC4280702 DOI: 10.1186/s12915-014-0099-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 11/07/2014] [Indexed: 12/14/2022] Open
Abstract
Background Despite being a fundamental biological problem the control of body size and proportions during development remains poorly understood, although it is accepted that the insulin-like growth factor (IGF) pathway has a central role in growth regulation, probably in all animals. The involvement of imprinted genes has also attracted much attention, not least because two of the earliest discovered were shown to be oppositely imprinted and antagonistic in their regulation of growth. The Igf2 gene encodes a paternally expressed ligand that promotes growth, while maternally expressed Igf2r encodes a cell surface receptor that restricts growth by sequestering Igf2 and targeting it for lysosomal degradation. There are now over 150 imprinted genes known in mammals, but no other clear examples of antagonistic gene pairs have been identified. The delta-like 1 gene (Dlk1) encodes a putative ligand that promotes fetal growth and in adults restricts adipose deposition. Conversely, Grb10 encodes an intracellular signalling adaptor protein that, when expressed from the maternal allele, acts to restrict fetal growth and is permissive for adipose deposition in adulthood. Results Here, using knockout mice, we present genetic and physiological evidence that these two factors exert their opposite effects on growth and physiology through a common signalling pathway. The major effects are on body size (particularly growth during early life), lean:adipose proportions, glucose regulated metabolism and lipid storage in the liver. A biochemical pathway linking the two cell signalling factors remains to be defined. Conclusions We propose that Dlk1 and Grb10 define a mammalian growth axis that is separate from the IGF pathway, yet also features an antagonistic imprinted gene pair. Electronic supplementary material The online version of this article (doi:10.1186/s12915-014-0099-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | - Andrew Ward
- Department of Biology & Biochemistry and Centre for Regenerative Medicine, University of Bath, Building 4 South, Claverton Down, Bath BA2 7AY, UK.
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14
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Garfield AS, Shah BP, Madara JC, Burke LK, Patterson CM, Flak J, Neve RL, Evans ML, Lowell BB, Myers MG, Heisler LK. A parabrachial-hypothalamic cholecystokinin neurocircuit controls counterregulatory responses to hypoglycemia. Cell Metab 2014; 20:1030-7. [PMID: 25470549 PMCID: PMC4261079 DOI: 10.1016/j.cmet.2014.11.006] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 09/29/2014] [Accepted: 11/07/2014] [Indexed: 11/15/2022]
Abstract
Hypoglycemia engenders an autonomically mediated counterregulatory (CR)-response that stimulates endogenous glucose production to maintain concentrations within an appropriate physiological range. Although the involvement of the brain in preserving normoglycemia has been established, the neurocircuitry underlying centrally mediated CR-responses remains unclear. Here we demonstrate that lateral parabrachial nucleus cholecystokinin (CCK(LPBN)) neurons are a population of glucose-sensing cells (glucose inhibited) with counterregulatory capacity. Furthermore, we reveal that steroidogenic-factor 1 (SF1)-expressing neurons of the ventromedial nucleus of the hypothalamus (SF1(VMH)) are the specific target of CCK(LPBN) glucoregulatory neurons. This discrete CCK(LPBN)→SF1(VMH) neurocircuit is both necessary and sufficient for the induction of CR-responses. Together, these data identify CCK(LPBN) neurons, and specifically CCK neuropeptide, as glucoregulatory and provide significant insight into the homeostatic mechanisms controlling CR-responses to hypoglycemia.
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Affiliation(s)
- Alastair S Garfield
- Centre for Integrative Physiology, Hugh Robson Building, University of Edinburgh, Edinburgh, EH8 9XD, UK; Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA.
| | - Bhavik P Shah
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Joseph C Madara
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Luke K Burke
- Department of Medicine and Wellcome Trust/Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK; Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, AB25 2ZD, UK
| | - Christa M Patterson
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48105, USA
| | - Jonathan Flak
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48105, USA
| | - Rachael L Neve
- Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Mark L Evans
- Department of Medicine and Wellcome Trust/Medical Research Council Institute of Metabolic Science, University of Cambridge, Cambridge, CB2 0QQ, UK
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Martin G Myers
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48105, USA
| | - Lora K Heisler
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, AB25 2ZD, UK
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15
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Flak JN, Patterson CM, Garfield AS, D'Agostino G, Goforth PB, Sutton AK, Malec PA, Wong JMT, Germani M, Jones JC, Rajala M, Satin L, Rhodes CJ, Olson DP, Kennedy RT, Heisler LK, Myers MG. Leptin-inhibited PBN neurons enhance responses to hypoglycemia in negative energy balance. Nat Neurosci 2014; 17:1744-1750. [PMID: 25383904 PMCID: PMC4255234 DOI: 10.1038/nn.3861] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 10/10/2014] [Indexed: 12/29/2022]
Abstract
Hypoglycemia initiates the counter regulatory response (CRR), in which the sympathetic nervous system, glucagon, and glucocorticoids restore glucose to appropriate concentrations. During starvation, low leptin restrains energy utilization, enhancing long-term survival. To ensure short-term survival during hypoglycemia in fasted animals, the CRR must overcome this energy-sparing program and nutrient depletion. Here, we identify in mice a previously unrecognized role for leptin and a population of leptin-regulated neurons that modulate the CRR to meet these challenges. Hypoglycemia activates leptin receptor (LepRb) and cholecystokinin (CCK)-expressing neurons of the parabrachial nucleus (PBN), which project to the ventromedial hypothalamic nucleus. Leptin inhibits these cells and Cckcre-mediated ablation of LepRb enhances the CRR. Inhibition of PBN LepRb cells blunts the CRR, while their activation mimics the CRR in a CCK-dependent manner. PBN LepRbCCK neurons represent a crucial component of the CRR system, and may represent a therapeutic target in hypoglycemia.
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Affiliation(s)
- Jonathan N Flak
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | | | | | - Giuseppe D'Agostino
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, and Department of Pharmacology, University of Cambridge, Cambridge, UK
| | | | - Amy K Sutton
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA.,Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Paige A Malec
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | | | - Mark Germani
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Justin C Jones
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Michael Rajala
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Leslie Satin
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | | | - David P Olson
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI, USA
| | - Robert T Kennedy
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Lora K Heisler
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen, and Department of Pharmacology, University of Cambridge, Cambridge, UK
| | - Martin G Myers
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA.,Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
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16
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Burke LK, Doslikova B, D'Agostino G, Garfield AS, Farooq G, Burdakov D, Low MJ, Rubinstein M, Evans ML, Billups B, Heisler LK. 5-HT obesity medication efficacy via POMC activation is maintained during aging. Endocrinology 2014; 155:3732-8. [PMID: 25051442 PMCID: PMC4164923 DOI: 10.1210/en.2014-1223] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The phenomenon commonly described as the middle-age spread is the result of elevated adiposity accumulation throughout adulthood until late middle-age. It is a clinical imperative to gain a greater understanding of the underpinnings of age-dependent obesity and, in turn, how these mechanisms may impact the efficacy of obesity treatments. In particular, both obesity and aging are associated with rewiring of a principal brain pathway modulating energy homeostasis, promoting reduced activity of satiety pro-opiomelanocortin (POMC) neurons within the arcuate nucleus of the hypothalamus (ARC). Using a selective ARC-deficient POMC mouse line, here we report that former obesity medications augmenting endogenous 5-hydroxytryptamine (5-HT) activity d-fenfluramine and sibutramine require ARC POMC neurons to elicit therapeutic appetite-suppressive effects. We next investigated whether age-related diminished ARC POMC activity therefore impacts the potency of 5-HT obesity pharmacotherapies, lorcaserin, d-fenfluramine, and sibutramine and report that all compounds reduced food intake to a comparable extent in both chow-fed young lean (3-5 months old) and middle-aged obese (12-14 months old) male and female mice. We provide a mechanism through which 5-HT anorectic potency is maintained with age, via preserved 5-HT-POMC appetitive anatomical machinery. Specifically, the abundance and signaling of the primary 5-HT receptor influencing appetite via POMC activation, the 5-HT2CR, is not perturbed with age. These data reveal that although 5-HT obesity medications require ARC POMC neurons to achieve appetitive effects, the anorectic efficacy is maintained with aging, findings of clinical significance to the global aging obese population.
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Affiliation(s)
- Luke K Burke
- Department of Pharmacology (L.K.B., B.D., G.D., A.S.G., G.F., D.B., B.B., L.K.H.) and Wellcome Trust/Medical Research Council Institute of Metabolic Science (M.L.E.), University of Cambridge, Cambridge, CB2 0QQ, United Kingdom; Rowett Institute of Nutrition and Health (G.D., L.K.H.), University of Aberdeen, Aberdeen, AB21 9SB, United Kingdom; Department of Molecular and Integrative Physiology (M.J.L., M.R.), University of Michigan Medical School, Ann Arbor, Michigan 48105; and Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (M.R.), Consejo Nacional de Investigaciones Científicas y Técnicas, 1428 Buenos Aires, Argentina
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17
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Garfield AS, Burke LK, Shaw J, Evans ML, Heisler LK. Distribution of cells responsive to 5-HT₆ receptor antagonist-induced hypophagia. Behav Brain Res 2014; 266:201-6. [PMID: 24566060 PMCID: PMC4003350 DOI: 10.1016/j.bbr.2014.02.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 02/11/2014] [Accepted: 02/13/2014] [Indexed: 11/29/2022]
Abstract
The central 5-hydroxytryptamine (5-HT; serotonin) system is well established as an important regulator of appetite and continues to remain a focus of obesity research. While much emphasis has focussed on the 5-HT2C receptor (5-HT2CR) in 5-HT's anorectic effect, pharmacological manipulation of the 5-HT6 receptor (5-HT6R) also reduces appetite and body weight and may be amenable to obesity treatment. However, the neurological circuits that underlie 5-HT6R-induced hypophagia remain to be identified. Using c-fos immunoreactivity (FOS-IR) as a marker of neuronal activation, here we mapped the neuroanatomical targets activated by an anorectic dose of the 5-HT6R antagonist SB-399885 throughout the brain. Furthermore, we quantified SB-399855 activated cells within brain appetitive nuclei, the hypothalamus, dorsal raphe nucleus (DRN) and nucleus of the solitary tract (NTS). Our results reveal that 5-HT6R antagonist-induced hypophagia is associated with significantly increased neuronal activation in two nuclei with an established role in the central control of appetite, the paraventricular nucleus of the hypothalamus (PVH) and the NTS. In contrast, no changes in FOS-IR were observed between treatment groups within other hypothalamic nuclei or DRN. The data presented here provide a first insight into the neural circuitry underlying 5-HT6R antagonist-induced appetite suppression and highlight the PVH and NTS in the coordination of 5-HT6R hypophagia.
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Affiliation(s)
- Alastair S Garfield
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK; Centre for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK.
| | - Luke K Burke
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
| | - Jill Shaw
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
| | - Mark L Evans
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge CB2 0QQ, UK
| | - Lora K Heisler
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK; Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen AB21 9SB, UK.
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18
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Krashes MJ, Shah BP, Madara JC, Olson DP, Strochlic DE, Garfield AS, Vong L, Pei H, Watabe-Uchida M, Uchida N, Liberles SD, Lowell BB. An excitatory paraventricular nucleus to AgRP neuron circuit that drives hunger. Nature 2014; 507:238-42. [PMID: 24487620 PMCID: PMC3955843 DOI: 10.1038/nature12956] [Citation(s) in RCA: 426] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 12/16/2013] [Indexed: 12/20/2022]
Abstract
Hunger is a hard-wired motivational state essential for survival. Agouti-related peptide (AgRP)-expressing neurons in the arcuate nucleus (ARC) at the base of the hypothalamus are crucial to the control of hunger. They are activated by caloric deficiency and, when naturally or artificially stimulated, they potently induce intense hunger and subsequent food intake. Consistent with their obligatory role in regulating appetite, genetic ablation or chemogenetic inhibition of AgRP neurons decreases feeding. Excitatory input to AgRP neurons is important in caloric-deficiency-induced activation, and is notable for its remarkable degree of caloric-state-dependent synaptic plasticity. Despite the important role of excitatory input, its source(s) has been unknown. Here, through the use of Cre-recombinase-enabled, cell-specific neuron mapping techniques in mice, we have discovered strong excitatory drive that, unexpectedly, emanates from the hypothalamic paraventricular nucleus, specifically from subsets of neurons expressing thyrotropin-releasing hormone (TRH) and pituitary adenylate cyclase-activating polypeptide (PACAP, also known as ADCYAP1). Chemogenetic stimulation of these afferent neurons in sated mice markedly activates AgRP neurons and induces intense feeding. Conversely, acute inhibition in mice with caloric-deficiency-induced hunger decreases feeding. Discovery of these afferent neurons capable of triggering hunger advances understanding of how this intense motivational state is regulated.
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Affiliation(s)
- Michael J Krashes
- 1] Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA [2] Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA (M.J.K.); National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA (M.J.K.); Cardiovascular and Metabolic Diseases, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, USA (B.P.S.); Division of Pediatric Endocrinology, Departments of Pediatrics, University of Michigan, Ann Arbor, Michigan 48105, USA (D.P.O.); Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, 100 Technology Square, Cambridge, Massachusetts 02139, USA (L.V.). [3]
| | - Bhavik P Shah
- 1] Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA [2] Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA (M.J.K.); National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA (M.J.K.); Cardiovascular and Metabolic Diseases, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, USA (B.P.S.); Division of Pediatric Endocrinology, Departments of Pediatrics, University of Michigan, Ann Arbor, Michigan 48105, USA (D.P.O.); Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, 100 Technology Square, Cambridge, Massachusetts 02139, USA (L.V.). [3]
| | - Joseph C Madara
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
| | - David P Olson
- 1] Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA [2] Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA (M.J.K.); National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA (M.J.K.); Cardiovascular and Metabolic Diseases, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, USA (B.P.S.); Division of Pediatric Endocrinology, Departments of Pediatrics, University of Michigan, Ann Arbor, Michigan 48105, USA (D.P.O.); Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, 100 Technology Square, Cambridge, Massachusetts 02139, USA (L.V.)
| | - David E Strochlic
- 1] Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA [2] Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Alastair S Garfield
- 1] Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA [2] Center for Integrative Physiology, University of Edinburgh, Edinburgh EH8 9XD, UK
| | - Linh Vong
- 1] Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA [2] Diabetes, Endocrinology and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA (M.J.K.); National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA (M.J.K.); Cardiovascular and Metabolic Diseases, Pfizer, 610 Main Street, Cambridge, Massachusetts 02139, USA (B.P.S.); Division of Pediatric Endocrinology, Departments of Pediatrics, University of Michigan, Ann Arbor, Michigan 48105, USA (D.P.O.); Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, 100 Technology Square, Cambridge, Massachusetts 02139, USA (L.V.)
| | - Hongjuan Pei
- Division of Pediatric Endocrinology, Departments of Pediatrics, University of Michigan, Ann Arbor, Michigan 48105, USA
| | - Mitsuko Watabe-Uchida
- Center for Brain Science, Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts 02138, USA
| | - Naoshige Uchida
- 1] Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115, USA [2] Center for Brain Science, Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts 02138, USA
| | - Stephen D Liberles
- 1] Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA [2] Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Bradford B Lowell
- 1] Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA [2] Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02115, USA
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19
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Cowley M, Garfield AS, Madon-Simon M, Charalambous M, Clarkson RW, Smalley MJ, Kendrick H, Isles AR, Parry AJ, Carney S, Oakey RJ, Heisler LK, Moorwood K, Wolf JB, Ward A. Developmental programming mediated by complementary roles of imprinted Grb10 in mother and pup. PLoS Biol 2014; 12:e1001799. [PMID: 24586114 PMCID: PMC3934836 DOI: 10.1371/journal.pbio.1001799] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 01/15/2014] [Indexed: 01/21/2023] Open
Abstract
Developmental programming links growth in early life with health status in adulthood. Although environmental factors such as maternal diet can influence the growth and adult health status of offspring, the genetic influences on this process are poorly understood. Using the mouse as a model, we identify the imprinted gene Grb10 as a mediator of nutrient supply and demand in the postnatal period. The combined actions of Grb10 expressed in the mother, controlling supply, and Grb10 expressed in the offspring, controlling demand, jointly regulate offspring growth. Furthermore, Grb10 determines the proportions of lean and fat tissue during development, thereby influencing energy homeostasis in the adult. Most strikingly, we show that the development of normal lean/fat proportions depends on the combined effects of Grb10 expressed in the mother, which has the greater effect on offspring adiposity, and Grb10 expressed in the offspring, which influences lean mass. These distinct functions of Grb10 in mother and pup act complementarily, which is consistent with a coadaptation model of imprinting evolution, a model predicted but for which there is limited experimental evidence. In addition, our findings identify Grb10 as a key genetic component of developmental programming, and highlight the need for a better understanding of mother-offspring interactions at the genetic level in predicting adult disease risk.
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Affiliation(s)
- Michael Cowley
- Department of Biology & Biochemistry and Centre for Regenerative Medicine, University of Bath, Bath, United Kingdom
- Department of Medical & Molecular Genetics, King's College London, London, United Kingdom
| | - Alastair S. Garfield
- Department of Biology & Biochemistry and Centre for Regenerative Medicine, University of Bath, Bath, United Kingdom
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Marta Madon-Simon
- Department of Biology & Biochemistry and Centre for Regenerative Medicine, University of Bath, Bath, United Kingdom
| | - Marika Charalambous
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | | | - Matthew J. Smalley
- European Cancer Stem Cell Research Institute, Cardiff School of Biosciences, Biomedical Sciences Building, Cardiff University, Cardiff, United Kingdom
| | - Howard Kendrick
- European Cancer Stem Cell Research Institute, Cardiff School of Biosciences, Biomedical Sciences Building, Cardiff University, Cardiff, United Kingdom
| | - Anthony R. Isles
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine and Psychology, Cardiff University, Cardiff, United Kingdom
| | - Aled J. Parry
- Department of Biology & Biochemistry and Centre for Regenerative Medicine, University of Bath, Bath, United Kingdom
| | - Sara Carney
- Department of Biology & Biochemistry and Centre for Regenerative Medicine, University of Bath, Bath, United Kingdom
| | - Rebecca J. Oakey
- Department of Medical & Molecular Genetics, King's College London, London, United Kingdom
| | - Lora K. Heisler
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Kim Moorwood
- Department of Biology & Biochemistry and Centre for Regenerative Medicine, University of Bath, Bath, United Kingdom
| | - Jason B. Wolf
- Department of Biology & Biochemistry and Centre for Regenerative Medicine, University of Bath, Bath, United Kingdom
| | - Andrew Ward
- Department of Biology & Biochemistry and Centre for Regenerative Medicine, University of Bath, Bath, United Kingdom
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20
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Abstract
Aversive visceral stimuli, such as those associated with sickness, suppress appetite. Yet an understanding of the neural mechanisms underlying illness-related anorexia has remained elusive. Carter et al. (2013) now identify a specific hindbrain → amygdala circuit that contributes to illness-induced loss of appetite.
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Affiliation(s)
- Alastair S Garfield
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK; Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, USA.
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21
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Doslikova B, Garfield AS, Shaw J, Evans ML, Burdakov D, Billups B, Heisler LK. 5-HT2C receptor agonist anorectic efficacy potentiated by 5-HT1B receptor agonist coapplication: an effect mediated via increased proportion of pro-opiomelanocortin neurons activated. J Neurosci 2013; 33:9800-4. [PMID: 23739976 PMCID: PMC3717514 DOI: 10.1523/jneurosci.4326-12.2013] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 02/08/2013] [Accepted: 02/26/2013] [Indexed: 11/21/2022] Open
Abstract
An essential component of the neural network regulating ingestive behavior is the brain 5-hydroxytryptamine2C receptor (5-HT2CR), agonists of which suppress food intake and were recently approved for obesity treatment by the US Food and Drug Administration. 5-HT2CR-regulated appetite is mediated primarily through activation of hypothalamic arcuate nucleus (ARC) pro-opiomelanocortin (POMC) neurons, which are also disinhibited through a 5-HT1BR-mediated suppression of local inhibitory inputs. Here we investigated whether 5-HT2CR agonist anorectic potency could be significantly enhanced by coadministration of a 5-HT1BR agonist and whether this was associated with augmented POMC neuron activation on the population and/or single-cell level. The combined administration of subanorectic concentrations of 5-HT2CR and 5-HT1BR agonists produced a 45% reduction in food intake and significantly greater in vivo ARC neuron activation in mice. The chemical phenotype of activated ARC neurons was assessed by monitoring agonist-induced cellular activity via calcium imaging in mouse POMC-EGFP brain slices, which revealed that combined agonists activated significantly more POMC neurons (46%) compared with either drug alone (∼25% each). Single-cell electrophysiological analysis demonstrated that 5-HT2CR/5-HT1BR agonist coadministration did not significantly potentiate the firing frequency of individual ARC POMC-EGFP cells compared with agonists alone. These data indicate a functional heterogeneity of ARC POMC neurons by revealing distinct subpopulations of POMC cells activated by 5-HT2CRs and disinhibited by 5-HT1BRs. Therefore, coadministration of a 5-HT1BR agonist potentiates the anorectic efficacy of 5-HT2CR compounds by increasing the number, but not the magnitude, of activated ARC POMC neurons and is of therapeutic relevance to obesity treatment.
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Affiliation(s)
| | | | | | - Mark L. Evans
- Institute of Metabolic Science, University of Cambridge, Cambridge CB2 1PD, United Kingdom, and
| | | | | | - Lora K. Heisler
- Department of Pharmacology and
- Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen AB21 9SB, United Kingdom
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22
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Garfield AS, Patterson C, Skora S, Gribble FM, Reimann F, Evans ML, Myers MG, Heisler LK. Neurochemical characterization of body weight-regulating leptin receptor neurons in the nucleus of the solitary tract. Endocrinology 2012; 153:4600-7. [PMID: 22869346 PMCID: PMC3507354 DOI: 10.1210/en.2012-1282] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Accepted: 07/12/2012] [Indexed: 11/19/2022]
Abstract
The action of peripherally released leptin at long-form leptin receptors (LepRb) within the brain represents a fundamental axis in the regulation of energy homeostasis and body weight. Efforts to delineate the neuronal mediators of leptin action have recently focused on extrahypothalamic populations and have revealed that leptin action within the nucleus of the solitary tract (NTS) is critical for normal appetite and body weight regulation. To elucidate the neuronal circuits that mediate leptin action within the NTS, we employed multiple transgenic reporter lines to characterize the neurochemical identity of LepRb-expressing NTS neurons. LepRb expression was not detected in energy balance-associated NTS neurons that express cocaine- and amphetamine-regulated transcript, brain-derived neurotrophic factor, neuropeptide Y, nesfatin, catecholamines, γ-aminobutyric acid, prolactin-releasing peptide, or nitric oxide synthase. The population of LepRb-expressing NTS neurons was comprised of subpopulations marked by a proopiomelanocortin-enhanced green fluorescent protein (EGFP) transgene and distinct populations that express proglucagon and/or cholecystokinin. The significance of leptin action on these three populations of NTS neurons was assessed in leptin-deficient Ob/Ob mice, revealing increased NTS proglucagon and cholecystokinin, but not proopiomelanocortin, expression. These data provide new insight into the appetitive brainstem circuits engaged by leptin.
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Affiliation(s)
- Alastair S Garfield
- University of Cambridge, Department of Pharmacology, Tennis Court Road, Cambridge CB2 1PD, United Kingdom.
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23
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Garfield AS, Chan WS, Dennis RJ, Ito D, Heisler LK, Rochford JJ. Neuroanatomical characterisation of the expression of the lipodystrophy and motor-neuropathy gene Bscl2 in adult mouse brain. PLoS One 2012; 7:e45790. [PMID: 23049863 PMCID: PMC3458087 DOI: 10.1371/journal.pone.0045790] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 08/24/2012] [Indexed: 01/14/2023] Open
Abstract
The endoplasmic reticulum localised protein seipin, encoded by the gene Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2), serves a critical but poorly defined function in the physiology of both adipose and neural tissue. In humans, BSCL2 loss-of-function mutations cause a severe form of lipodystrophy, whilst a distinct set of gain-of-toxic-function mutations are associated with a heterogeneous group of neuropathies. However, despite the importance of seipin dysfunction to the pathophysiology of these conditions, little is known about its physiological role in adipocytes or neurons. BSCL2 mRNA has previously been identified in human and mouse brain, yet no definitive assessment of its expression has been undertaken. Here we comprehensively characterised the neuroanatomical distribution of mouse Bscl2 using complementary in situ hybridisation histochemistry and immunohistochemistry techniques. Whilst Bscl2 was broadly expressed throughout the rostral-caudal extent of the mouse brain, it exhibited a discrete neuroanatomical profile. Bscl2 was most abundantly expressed in the hypothalamus and in particular regions associated with the regulation of energy balance including, the paraventricular, ventromedial, arcuate and dorsomedial nuclei. Bscl2 expression was also identified within the brainstem dorsal vagal complex, which together with the paraventricular nucleus of the hypothalamus represented the site of highest expression. Further neurochemical profiling of these two nuclei revealed Bscl2/seipin expression within energy balance related neuronal populations. Specifically, seipin was detected in oxytocin neurons of the paraventricular nucleus of the hypothalamus and in catecholamine neurons of the dorsal vagal complex. These data raise the possibility that in addition to its role in adipose tissue development, seipin may also be involved in the central regulation of energy balance.
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Affiliation(s)
| | - Wai S. Chan
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Rowena J. Dennis
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom
| | - Daisuke Ito
- Department of Neurology, School of Medicine, Keio University, Shinjuku-ku, Tokyo, Japan
| | - Lora K. Heisler
- Department of Pharmacology, University of Cambridge, Cambridge, United Kingdom
| | - Justin J. Rochford
- University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, United Kingdom
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24
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Hurst P, Garfield AS, Marrow C, Heisler LK, Evans ML. Recurrent hypoglycemia is associated with loss of activation in rat brain cingulate cortex. Endocrinology 2012; 153:1908-14. [PMID: 22396449 PMCID: PMC3328129 DOI: 10.1210/en.2011-1827] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 01/26/2012] [Indexed: 12/30/2022]
Abstract
A subset of people with diabetes fail to mount defensive counterregulatory responses (CRR) to hypoglycemia. Although the mechanisms by which this occurs remain unclear, recurrent exposure to hypoglycemia may be an important etiological factor. We hypothesized that loss of CRR to recurrent exposure to hypoglycemia represents a type of stress desensitization, in which limbic brain circuitry involved in modulating stress responses might be implicated. Here, we compared activation of limbic brain regions associated with stress desensitization during acute hypoglycemia (AH) and recurrent hypoglycemia (RH). Healthy Sprague Dawley rats were exposed to either acute or recurrent 3-d hypoglycemia. We also examined whether changes in neuronal activation were caused directly by the CRR itself by infusing epinephrine, glucagon, and corticosterone without hypoglycemia. AH increased neuronal activity as quantified by c-fos immunoreactivity (FOS-IR) in the cingulate cortex and associated ectorhinal and perirhinal cortices but not in an adjacent control area (primary somatosensory cortex). FOS-IR was not observed after hormone infusion, suggesting that AH-associated activation was caused by hypoglycemia rather than by CRR. Importantly, AH FOS-IR activation was significantly blunted in rats exposed to RH. In conclusion, analogous with other models of stress habituation, activation in the cingulate cortex and associated brain areas is lost with exposure to RH. Our data support the hypothesis that limbic brain areas may be associated with the loss of CRR to RH in diabetes.
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Affiliation(s)
- Paul Hurst
- University of Cambridge Metabolic Research Laboratories/Department of Medicine/National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge CB2 0QQ, United Kingdom
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25
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Zhou L, Yueh CY, Lam DD, Shaw J, Osundiji M, Garfield AS, Evans M, Heisler LK. Glucokinase inhibitor glucosamine stimulates feeding and activates hypothalamic neuropeptide Y and orexin neurons. Behav Brain Res 2011; 222:274-8. [PMID: 21440571 PMCID: PMC3133639 DOI: 10.1016/j.bbr.2011.03.043] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/16/2011] [Accepted: 03/17/2011] [Indexed: 12/05/2022]
Abstract
Maintaining glucose levels within the appropriate physiological range is necessary for survival. The identification of specific neuronal populations, within discreet brain regions, sensitive to changes in glucose concentration has led to the hypothesis of a central glucose-sensing system capable of directly modulating feeding behaviour. Glucokinase (GK) has been identified as a glucose-sensor responsible for detecting such changes both within the brain and the periphery. We previously reported that antagonism of centrally expressed GK by administration of glucosamine (GSN) was sufficient to induce protective glucoprivic feeding in rats. Here we examine a neurochemical mechanism underlying this effect and report that GSN stimulated food intake is highly correlated with the induction of the neuronal activation marker cFOS within two nuclei with a demonstrated role in central glucose sensing and appetite, the arcuate nucleus of the hypothalamus (ARC) and lateral hypothalamic area (LHA). Furthermore, GSN stimulated cFOS within the ARC was observed in orexigenic neurons expressing the endogenous melanocortin receptor antagonist agouti-related peptide (AgRP) and neuropeptide Y (NPY), but not those expressing the anorectic endogenous melanocortin receptor agonist alpha-melanocyte stimulating hormone (α-MSH). In the LHA, GSN stimulated cFOS was found within arousal and feeding associated orexin/hypocretin (ORX), but not orexigenic melanin-concentrating hormone (MCH) expressing neurons. Our data suggest that GK within these specific feeding and arousal related populations of AgRP/NPY and ORX neurons may play a modulatory role in the sensing of and appetitive response to hypoglycaemia.
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Affiliation(s)
- Ligang Zhou
- Department of Pharmacology, University of Cambridge, Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
- Department of Endocrinology, Shuguang Hospital, Shanghai University of TCM, China
| | - Chen-Yu Yueh
- Institute of Metabolic Science, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
- Department of Family Medicine, Chang Gung Memorial Hospital at Chiayi, Taiwan; Chang Gung Institute of Technology, Taiwan
| | - Daniel D. Lam
- Department of Pharmacology, University of Cambridge, Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Jill Shaw
- Institute of Metabolic Science, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Mayowa Osundiji
- Institute of Metabolic Science, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Alastair S. Garfield
- Department of Pharmacology, University of Cambridge, Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Mark Evans
- Institute of Metabolic Science, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Lora K. Heisler
- Department of Pharmacology, University of Cambridge, Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
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26
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Marston OJ, Garfield AS, Heisler LK. Role of central serotonin and melanocortin systems in the control of energy balance. Eur J Pharmacol 2011; 660:70-9. [DOI: 10.1016/j.ejphar.2010.12.024] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 12/22/2010] [Indexed: 11/28/2022]
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27
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Lam DD, Leinninger GM, Louis GW, Garfield AS, Marston OJ, Leshan RL, Scheller EL, Christensen L, Donato J, Xia J, Evans ML, Elias C, Dalley JW, Burdakov DI, Myers MG, Heisler LK. Leptin does not directly affect CNS serotonin neurons to influence appetite. Cell Metab 2011; 13:584-91. [PMID: 21531340 PMCID: PMC3087147 DOI: 10.1016/j.cmet.2011.03.016] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 12/28/2010] [Accepted: 03/18/2011] [Indexed: 01/11/2023]
Abstract
Serotonin (5-HT) and leptin play important roles in the modulation of energy balance. Here we investigated mechanisms by which leptin might interact with CNS 5-HT pathways to influence appetite. Although some leptin receptor (LepRb) neurons lie close to 5-HT neurons in the dorsal raphe (DR), 5-HT neurons do not express LepRb. Indeed, while leptin hyperpolarizes some non-5-HT DR neurons, leptin does not alter the activity of DR 5-HT neurons. Furthermore, 5-HT depletion does not impair the anorectic effects of leptin. The serotonin transporter-cre allele (Sert(cre)) is expressed in 5-HT (and developmentally in some non-5-HT) neurons. While Sert(cre) promotes LepRb excision in a few LepRb neurons in the hypothalamus, it is not active in DR LepRb neurons, and neuron-specific Sert(cre)-mediated LepRb inactivation in mice does not alter body weight or adiposity. Thus, leptin does not directly influence 5-HT neurons and does not meaningfully modulate important appetite-related determinants via 5-HT neuron function.
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Affiliation(s)
- Daniel D. Lam
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
| | - Gina M. Leinninger
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Gwendolyn W. Louis
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Oliver J. Marston
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
| | - Rebecca L. Leshan
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Erica L. Scheller
- School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Lyndsay Christensen
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jose Donato
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9077, USA
| | - Jing Xia
- Behavioural and Clinical Neuroscience Institute and Department of Experimental Psychology, University of Cambridge, Cambridge CB2 1PD, UK
| | - Mark L. Evans
- Institute of Metabolic Science, University of Cambridge, Cambridge CB2 1PD, UK
| | - Carol Elias
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9077, USA
| | - Jeffrey W. Dalley
- Behavioural and Clinical Neuroscience Institute and Department of Experimental Psychology, University of Cambridge, Cambridge CB2 1PD, UK
- Department of Psychiatry, University of Cambridge, Cambridge CB2 1PD, UK
| | - Denis I. Burdakov
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
| | - Martin G. Myers
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Lora K. Heisler
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
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28
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Garfield AS, Cowley M, Smith FM, Moorwood K, Stewart-Cox JE, Gilroy K, Baker S, Xia J, Dalley JW, Hurst LD, Wilkinson LS, Isles AR, Ward A. Distinct physiological and behavioural functions for parental alleles of imprinted Grb10. Nature 2011; 469:534-8. [PMID: 21270893 PMCID: PMC3031026 DOI: 10.1038/nature09651] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 11/04/2010] [Indexed: 02/02/2023]
Abstract
Imprinted genes, defined by their preferential expression of a single parental allele, represent a subset of the mammalian genome and often have key roles in embryonic development, but also postnatal functions including energy homeostasis and behaviour. When the two parental alleles are unequally represented within a social group (when there is sex bias in dispersal and/or variance in reproductive success), imprinted genes may evolve to modulate social behaviour, although so far no such instance is known. Predominantly expressed from the maternal allele during embryogenesis, Grb10 encodes an intracellular adaptor protein that can interact with several receptor tyrosine kinases and downstream signalling molecules. Here we demonstrate that within the brain Grb10 is expressed from the paternal allele from fetal life into adulthood and that ablation of this expression engenders increased social dominance specifically among other aspects of social behaviour, a finding supported by the observed increase in allogrooming by paternal Grb10-deficient animals. Grb10 is, therefore, the first example of an imprinted gene that regulates social behaviour. It is also currently alone in exhibiting imprinted expression from each of the parental alleles in a tissue-specific manner, as loss of the peripherally expressed maternal allele leads to significant fetal and placental overgrowth. Thus Grb10 is, so far, a unique imprinted gene, able to influence distinct physiological processes, fetal growth and adult behaviour, owing to actions of the two parental alleles in different tissues.
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Affiliation(s)
- Alastair S. Garfield
- University of Bath, Department of Biology & Biochemistry and Centre for Regenerative Medicine, Claverton Down, Bath, BA2 7AY, UK,Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine, and Psychology, Cardiff University, Cardiff, CF14 4XN, UK
| | - Michael Cowley
- University of Bath, Department of Biology & Biochemistry and Centre for Regenerative Medicine, Claverton Down, Bath, BA2 7AY, UK
| | - Florentia M. Smith
- University of Bath, Department of Biology & Biochemistry and Centre for Regenerative Medicine, Claverton Down, Bath, BA2 7AY, UK
| | - Kim Moorwood
- University of Bath, Department of Biology & Biochemistry and Centre for Regenerative Medicine, Claverton Down, Bath, BA2 7AY, UK
| | - Joanne E. Stewart-Cox
- University of Bath, Department of Biology & Biochemistry and Centre for Regenerative Medicine, Claverton Down, Bath, BA2 7AY, UK
| | - Kerry Gilroy
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine, and Psychology, Cardiff University, Cardiff, CF14 4XN, UK
| | - Sian Baker
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine, and Psychology, Cardiff University, Cardiff, CF14 4XN, UK
| | - Jing Xia
- Behavioural and Clinical Neuroscience Institute and Department of Experimental Psychology, University of Cambridge, Downing St, Cambridge, CB2 3EB, UK
| | - Jeffrey W. Dalley
- Behavioural and Clinical Neuroscience Institute and Department of Experimental Psychology, University of Cambridge, Downing St, Cambridge, CB2 3EB, UK,Department of Psychiatry, University of Cambridge, Addenbrooke's Hospital, Hill's Road, Cambridge, CB2 2QQ, UK
| | - Laurence D. Hurst
- University of Bath, Department of Biology & Biochemistry and Centre for Regenerative Medicine, Claverton Down, Bath, BA2 7AY, UK
| | - Lawrence S. Wilkinson
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine, and Psychology, Cardiff University, Cardiff, CF14 4XN, UK
| | - Anthony R. Isles
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, Neuroscience and Mental Health Research Institute, Schools of Medicine, and Psychology, Cardiff University, Cardiff, CF14 4XN, UK
| | - Andrew Ward
- University of Bath, Department of Biology & Biochemistry and Centre for Regenerative Medicine, Claverton Down, Bath, BA2 7AY, UK,Author for correspondence: Dr Andrew Ward, Tel: 00(44)1225 386914, Fax: 00(44)1225 386779,
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Lam DD, Garfield AS, Marston OJ, Shaw J, Heisler LK. Brain serotonin system in the coordination of food intake and body weight. Pharmacol Biochem Behav 2010; 97:84-91. [PMID: 20837046 DOI: 10.1016/j.pbb.2010.09.003] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 08/02/2010] [Accepted: 09/06/2010] [Indexed: 11/30/2022]
Abstract
An inverse relationship between brain serotonin and food intake and body weight has been known for more than 30 years. Specifically, augmentation of brain serotonin inhibits food intake, while depletion of brain serotonin promotes hyperphagia and weight gain. Through the decades, serotonin receptors have been identified and their function in the serotonergic regulation of food intake clarified. Recent refined genetic studies now indicate that a primary mechanism through which serotonin influences appetite and body weight is via serotonin 2C receptor (5-HT(2C)R) and serotonin 1B receptor (5-HT(1B)R) influencing the activity of endogenous melanocortin receptor agonists and antagonists at the melanocortin 4 receptor (MC4R). However, other mechanisms are also possible and the challenge of future research is to delineate them in the complete elucidation of the complex neurocircuitry underlying the serotonergic control of appetite and body weight.
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Affiliation(s)
- Daniel D Lam
- Department of Pharmacology, University of Cambridge, Cambridge, UK
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30
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Przydzial MJ, Garfield AS, Lam DD, Moore SP, Evans ML, Heisler LK. Nutritional state influences Nociceptin/Orphanin FQ peptide receptor expression in the dorsal raphe nucleus. Behav Brain Res 2010; 206:313-7. [PMID: 19765615 PMCID: PMC2783909 DOI: 10.1016/j.bbr.2009.09.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2008] [Revised: 08/26/2009] [Accepted: 09/11/2009] [Indexed: 11/28/2022]
Abstract
Agonists of the nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor stimulate food intake. Concordantly, neuroanatomical localization of NOP receptor mRNA has revealed it to be highly expressed in brain regions associated with the regulation of energy balance. However, the specific mechanisms and neurochemical pathways through which physiological N/OFQ influences appetite are not well understood. To investigate this, we examined nutritional state-associated changes in NOP receptor mRNA levels throughout the rostrocaudal extent of the rat brain using in situ hybridization histochemistry (ISHH) and quantitative densitometry analysis. We observed a significant downregulation of NOP receptor mRNA in the dorsal raphe nucleus (DRN) of fasted rats compared to free-feeding rats. In contrast, no difference in NOP receptor mRNA expression was observed in the supraoptic, parventricular, ventromedial, arcuate or dorsomedial nuclei of the hypothalamus, the red nucleus, the locus coeruleus or the hypoglossal nucleus in the fasted or fed state. These data suggest that the endogenous N/OFQ system is responsive to changes in energy balance and that NOP receptors specifically within the DRN may be physiologically relevant to N/OFQ's effects on appetite.
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Affiliation(s)
| | | | - Daniel D. Lam
- Department of Pharmacology, University of Cambridge,
Cambridge, CB2 1PD, UK
| | - Stephen P. Moore
- Metabolic Research Laboratories, Institute of Metabolic
Science, Addenbrooke’s Hospital, University of Cambridge, Cambridge CB2 2QQ,
UK
| | - Mark L. Evans
- Metabolic Research Laboratories, Institute of Metabolic
Science, Addenbrooke’s Hospital, University of Cambridge, Cambridge CB2 2QQ,
UK
| | - Lora K. Heisler
- Department of Pharmacology, University of Cambridge,
Cambridge, CB2 1PD, UK
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31
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Abstract
Primary mouse embryonic fibroblasts (PMEFs) have a number of properties that make them an attractive cell culture model. Relative to other primary explant cultures they are easy to establish and maintain, proliferate rapidly and, as a result, large numbers of cells can be produced from a single embryo within several days following explantation. This allows, for instance, for ready comparison of wild-type and knockout cells derived from the same litter of animals. PMEFs can be expanded through several passages before they reach crisis and can be used to establish cell lines following spontaneous transformation or following derivation from strains carrying mutations, such as in the gene encoding the tumour suppressor Trp53. They have been widely used as feeders to support other cultured cell types, notably embryonic stem cells, as well as for the study of a diverse range of cellular phenomena using microscopic, biochemical and molecular biological techniques. Here, we describe a simple and reliable method for the derivation and maintenance of PMEFs.
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32
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Alon T, Zhou L, Pérez CA, Garfield AS, Friedman JM, Heisler LK. Transgenic mice expressing green fluorescent protein under the control of the corticotropin-releasing hormone promoter. Endocrinology 2009; 150:5626-32. [PMID: 19854866 PMCID: PMC2795705 DOI: 10.1210/en.2009-0881] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CRH is widely expressed in the brain and is of broad functional relevance to a number of physiological processes, including stress response, parturition, immune response, and ingestive behavior. To delineate further the organization of the central CRH network, we generated mice expressing green fluorescent protein (GFP) under the control of the CRH promoter, using bacterial artificial chromosome technology. Here we validate CRH-GFP transgene expression within specific brain regions and confirm the distribution of central GFP-producing cells to faithfully recapitulate that of CRH-expressing cells. Furthermore, we confirm the functional integrity of a population of GFP-producing cells by demonstrating their opposite responsiveness to nutritional status. We anticipate that this transgenic model will lend itself as a highly tractable tool for the investigation of CRH expression and function in discrete brain regions.
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Affiliation(s)
- Tamar Alon
- Laboratory of Molecular Genetics and Howard Hughes Medical Institute, Rockefeller University, New York, New York 10065, USA
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33
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Madon MM, Garfield AS, Cowley M, Ward A. 02-P016 Characterisation of the imprinted genes in mouse: Grb10 and Dlk1. Mech Dev 2009. [DOI: 10.1016/j.mod.2009.06.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Garfield AS, Lam DD, Marston OJ, Przydzial MJ, Heisler LK. Role of central melanocortin pathways in energy homeostasis. Trends Endocrinol Metab 2009; 20:203-15. [PMID: 19541496 DOI: 10.1016/j.tem.2009.02.002] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 02/06/2009] [Accepted: 02/06/2009] [Indexed: 02/07/2023]
Abstract
The rise in the global prevalence of human obesity has emphasized the need for a greater understanding of the physiological mechanisms that underlie energy homeostasis. Numerous circulating nutritional cues and central neuromodulatory signals are integrated within the brain to regulate both short- and long-term nutritional state. The central melanocortin system represents a crucial point of convergence for these signals and, thus, has a fundamental role in regulating body weight. The melanocortin ligands, synthesized in discrete neuronal populations within the hypothalamus and brainstem, modulate downstream homeostatic signalling via their action at central melanocortin-3 and -4 receptors. Intimately involved in both ingestive behaviour and energy expenditure, the melanocortin system has garnered much interest as a potential therapeutic target for human obesity.
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Affiliation(s)
- Alastair S Garfield
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
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35
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Doe CM, Relkovic D, Garfield AS, Dalley JW, Theobald DEH, Humby T, Wilkinson LS, Isles AR. Loss of the imprinted snoRNA mbii-52 leads to increased 5htr2c pre-RNA editing and altered 5HT2CR-mediated behaviour. Hum Mol Genet 2009; 18:2140-8. [PMID: 19304781 DOI: 10.1093/hmg/ddp137] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Prader-Willi syndrome (PWS) genetic interval contains several brain-expressed small nucleolar (sno)RNA species that are subject to genomic imprinting. In vitro studies have shown that one of these snoRNA molecules, h/mbii-52, negatively regulates editing and alternative splicing of the serotonin 2C receptor (5htr2c) pre-RNA. However, the functional consequences of loss of h/mbii-52 and subsequent increased post-transcriptional modification of 5htr2c are unknown. 5HT2CRs are important in controlling aspects of cognition and the cessation of feeding, and disruption of their function may underlie some of the psychiatric and feeding abnormalities seen in PWS. In a mouse model for PWS lacking expression of mbii-52 (PWS-IC+/-), we show an increase in editing, but not alternative splicing, of the 5htr2c pre-RNA. This change in post-transcriptional modification is associated with alterations in a number of 5HT2CR-related behaviours, including impulsive responding, locomotor activity and reactivity to palatable foodstuffs. In a non-5HT2CR-related behaviour, marble burying, loss of mbii-52 was without effect. The specificity of the behavioural effects to changes in 5HT2CR function was further confirmed using drug challenges. These data illustrate, for the first time, the physiological consequences of altered RNA editing of 5htr2c linked to mbii-52 loss that may underlie specific aspects of the complex PWS phenotype and point to an important functional role for this imprinted snoRNA.
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Affiliation(s)
- Christine M Doe
- Behavioural Genetics Group, Department of Psychological Medicine and Neurology (School of Medicine) and School of Psychology, Cardiff University, Cardiff, UK
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Abstract
The attenuation of food intake as induced by an increase in serotonergic (5-hydroxytryptamine, 5-HT) efficacy has been a target of antiobesity pharmacotherapies. However, the induction of tolerance and/or side-effects limited the clinical utility of the earliest serotonin-related medications. With the global prevalence of obesity rising, there has been renewed interest in the manipulation of the serotonergic system as a point of pharmacological intervention. The serotonin(2C) receptor (5-HT(2C)R), serotonin(1B) (rodent)/serotonin(1Dbeta) (human) receptor (5-HT(1B/1Dbeta)R) and serotonin(6) receptor (5-HT(6)R) represent the most promising serotonin receptor therapeutic targets. Canonical serotonin receptor compounds have given way to a myriad of novel receptor-selective ligands, many of which have observable anorectic effects. Here we review serotonergic compounds reducing ingestive behaviour and discuss their clinical potential for the treatment of obesity.
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Affiliation(s)
- Alastair S Garfield
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
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Smith FM, Holt LJ, Garfield AS, Charalambous M, Koumanov F, Perry M, Bazzani R, Sheardown SA, Hegarty BD, Lyons RJ, Cooney GJ, Daly RJ, Ward A. Mice with a disruption of the imprinted Grb10 gene exhibit altered body composition, glucose homeostasis, and insulin signaling during postnatal life. Mol Cell Biol 2007; 27:5871-86. [PMID: 17562854 PMCID: PMC1952119 DOI: 10.1128/mcb.02087-06] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The Grb10 adapter protein is capable of interacting with a variety of receptor tyrosine kinases, including, notably, the insulin receptor. Biochemical and cell culture experiments have indicated that Grb10 might act as an inhibitor of insulin signaling. We have used mice with a disruption of the Grb10 gene (Grb10Delta2-4 mice) to assess whether Grb10 might influence insulin signaling and glucose homeostasis in vivo. Adult Grb10Delta2-4 mice were found to have improved whole-body glucose tolerance and insulin sensitivity, as well as increased muscle mass and reduced adiposity. Tissue-specific changes in insulin receptor tyrosine phosphorylation were consistent with a model in which Grb10, like the closely related Grb14 adapter protein, prevents specific protein tyrosine phosphatases from accessing phosphorylated tyrosines within the kinase activation loop. Furthermore, insulin-induced IRS-1 tyrosine phosphorylation was enhanced in Grb10Delta2-4 mutant animals, supporting a role for Grb10 in attenuation of signal transmission from the insulin receptor to IRS-1. We have previously shown that Grb10 strongly influences growth of the fetus and placenta. Thus, Grb10 forms a link between fetal growth and glucose-regulated metabolism in postnatal life and is a candidate for involvement in the process of fetal programming of adult metabolic health.
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Affiliation(s)
- Florentia M Smith
- University of Bath, Developmental Biology Program and Centre for Regenerative Medicine, Department of Biology and Biochemistry, Claverton Down, Bath BA2 7AY, United Kingdom
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38
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Smith FM, Garfield AS, Ward A. Regulation of growth and metabolism by imprinted genes. Cytogenet Genome Res 2006; 113:279-91. [PMID: 16575191 DOI: 10.1159/000090843] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Accepted: 07/21/2005] [Indexed: 01/05/2023] Open
Abstract
A small sub-set of mammalian genes are subject to regulation by genomic imprinting such that only one parental allele is active in at least some sites of expression. Imprinted genes have diverse functions, notably including the regulation of growth. Much attention has been devoted to the insulin-like growth factor signalling pathway that has a major influence on fetal size and contains two components encoded by the oppositely imprinted genes, Igf2 (a growth promoting factor expressed from the paternal allele) and Igf2r (a growth inhibitory factor expressed from the maternal allele). These genes fit the parent-offspring conflict hypothesis for the evolution of genomic imprinting. Accumulated evidence indicates that at least one other fetal growth pathway exists that has also fallen under the influence of imprinting. It is clear that not all components of growth regulatory pathways are encoded by imprinted genes and instead it may be that within a pathway the influence of a single gene by each of the parental genomes may be sufficient for parent-offspring conflict to be enacted. A number of imprinted genes have been found to influence energy homeostasis and some, including Igf2 and Grb10, may coordinate growth with glucose-regulated metabolism. Since perturbation of fetal growth can be correlated with metabolic disorders in adulthood these imprinted genes are considered as candidates for involvement in this phenomenon of fetal programming.
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Affiliation(s)
- F M Smith
- Centre for Regenerative Medicine and Developmental Biology Programme, Department of Biology and Biochemistry, University of Bath, Bath, UK
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39
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Affiliation(s)
- R W Baird
- Cabrini Hospital, Victoria, Australia
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