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Tarhan M, Hartl T, Shchyglo O, Colitti-Klausnitzer J, Kuhla A, Breuer TM, Manahan-Vaughan D. Changes in hippocampal volume, synaptic plasticity and amylin sensitivity in an animal model of type 2 diabetes are associated with increased vulnerability to amyloid-beta in advancing age. Front Aging Neurosci 2024; 16:1373477. [PMID: 38974903 PMCID: PMC11224464 DOI: 10.3389/fnagi.2024.1373477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 05/28/2024] [Indexed: 07/09/2024] Open
Abstract
Type-2 diabetes (T2D) is a metabolic disorder that is considered a risk factor for Alzheimer's disease (AD). Cognitive impairment can arise due to hypoglycemia associated with T2D, and hyperamylinemia associated with insulin resistance can enhance AD pathology. We explored whether changes occur in the hippocampus in aging (6-12 months old) female V-Lep○b-/- transgenic (tg) mice, comprising an animal model of T2D. We also investigated whether an increase in vulnerability to Aβ (1-42), a known pathological hallmark of AD, is evident. Using magnetic resonance imaging we detected significant decreases in hippocampal brain volume in female tg-mice compared to wild-type (wt) littermates. Long-term potentiation (LTP) was impaired in tg compared to wt mice. Treatment of the hippocampus with Aβ (1-42) elicited a stronger debilitation of LTP in tg compared to wt mice. Treatment with an amylin antagonist (AC187) significantly enhanced LTP in wt and tg mice, and rescued LTP in Aβ (1-42)-treated tg mice. Taken together our data indicate that a T2D-like state results in an increased vulnerability of the hippocampus to the debilitating effects of Aβ (1-42) and that effects are mediated in part by changes in amylin receptor signaling.
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Affiliation(s)
- Melih Tarhan
- Department of Neurophysiology, Institute of Physiology, Ruhr University Bochum, Bochum, Germany
- International Graduate School of Neuroscience, Bochum, Germany
| | - Tim Hartl
- Department of Neurophysiology, Institute of Physiology, Ruhr University Bochum, Bochum, Germany
- International Graduate School of Neuroscience, Bochum, Germany
| | - Olena Shchyglo
- Department of Neurophysiology, Institute of Physiology, Ruhr University Bochum, Bochum, Germany
| | | | - Angela Kuhla
- Rudolf Zenker Institute for Experimental Surgery, Rostock University Medical Center, Rostock, Germany
| | | | - Denise Manahan-Vaughan
- Department of Neurophysiology, Institute of Physiology, Ruhr University Bochum, Bochum, Germany
- International Graduate School of Neuroscience, Bochum, Germany
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Buller S, Blouet C. Brain access of incretins and incretin receptor agonists to their central targets relevant for appetite suppression and weight loss. Am J Physiol Endocrinol Metab 2024; 326:E472-E480. [PMID: 38381398 PMCID: PMC11193531 DOI: 10.1152/ajpendo.00250.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 01/05/2024] [Accepted: 02/13/2024] [Indexed: 02/22/2024]
Abstract
New incretin-based pharmacotherapies provide efficient and safe therapeutic options to curb appetite and produce weight loss in patients with obesity. Delivered systemically, these molecules produce pleiotropic metabolic benefits, but the target sites mediating their weight-suppressive action are located within the brain. Recent research has increased our understanding of the neural circuits and behavioral mechanisms involved in the anorectic and metabolic consequences of glucagon-like peptide 1 (GLP-1)-based weight loss strategies, yet little is known about how these drugs access their functional targets in the brain to produce sustained weight loss. The majority of brain cells expressing incretin receptors are located behind the blood-brain barrier, shielded from the circulation and fluctuations in the availability of peripheral signals, which is a major challenge for the development of CNS-targeted therapeutic peptides. GLP-1 receptor (GLP-1R) agonists with increased half-life and enhanced therapeutic benefit do not cross the blood-brain barrier, yet they manage to access discrete brain sites relevant to the regulation of energy homeostasis. In this review, we give a brief overview of the different routes for peptide hormones to access the brain. We then examine the evidence informing the routes employed by incretins and incretin receptor agonists to access brain targets relevant for their appetite and weight-suppressive actions. We highlight existing controversies and suggest future directions to further establish the functionally relevant access routes for GLP-1-based weight loss compounds, which might guide the development and selection of the future generation of incretin receptor polypharmacologies.
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Affiliation(s)
- Sophie Buller
- Medical Research Council (MRC) Metabolic Diseases Unit, Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
| | - Clemence Blouet
- Medical Research Council (MRC) Metabolic Diseases Unit, Institute of Metabolic Science, University of Cambridge, Cambridge, United Kingdom
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3
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Ben Dhaou C, Terrié E, Déliot N, Harnois T, Cousin L, Arnault P, Constantin B, Moyse E, Coronas V. Neural stem cell self-renewal stimulation by store-operated calcium entries in adult mouse area postrema: influence of leptin. Front Cell Neurosci 2023; 17:1200360. [PMID: 37361995 PMCID: PMC10287973 DOI: 10.3389/fncel.2023.1200360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 05/17/2023] [Indexed: 06/28/2023] Open
Abstract
Neural stem cells (NSCs) persist in specific brain germinative niches and sustain neurogenesis throughout life in adult mammals. In addition to the two major stem cell niches in the subventricular zone and the hippocampal dentate gyrus, the area postrema located in the brainstem has been identified as a neurogenic zone as well. NSCs are regulated by signals from the microenvironment that adjust stem cell response to the needs of the organism. Evidence accumulated over the past decade indicates that Ca2+ channels play pivotal functions in NSC maintenance. In this study, we explored in area postrema NSCs the presence and roles of a subset of Ca2+ channels, the store-operated Ca2+ channels (SOCs) that have the capacity to transduce extracellular signals into Ca2+ signals. Our data show that NSCs derived from the area postrema express TRPC1 and Orai1, known to form SOCs, as well as their activator STIM1. Ca2+ imaging indicated that NSCs exhibit store-operated Ca2+ entries (SOCEs). Pharmacological blockade of SOCEs with SKF-96365, YM-58483 (also known as BTP2) or GSK-7975A resulted in decreased NSC proliferation and self-renewal, indicating a major role for SOCs in maintaining NSC activity within the area postrema. Furthermore, our results show that leptin, an adipose tissue-derived hormone whose ability to control energy homeostasis is dependent on the area postrema, decreased SOCEs and reduced self-renewal of NSCs in the area postrema. As aberrant SOC function has been linked to an increasing number of diseases, including brain disorders, our study opens new perspectives for NSCs in brain pathophysiology.
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Affiliation(s)
- Cyrine Ben Dhaou
- University of Tours, INRAe Centre Val-de-Loire UMR-85, CNRS UMR-1247, Physiologie de la Reproduction et Comportements, Nouzilly, France
| | - Elodie Terrié
- 4CS, Laboratory Channels and Connexins in Cancers and Cell Stemness, CNRS UMR 6041, University of Poitiers, Poitiers, France
| | - Nadine Déliot
- 4CS, Laboratory Channels and Connexins in Cancers and Cell Stemness, CNRS UMR 6041, University of Poitiers, Poitiers, France
| | - Thomas Harnois
- 4CS, Laboratory Channels and Connexins in Cancers and Cell Stemness, CNRS UMR 6041, University of Poitiers, Poitiers, France
| | - Laetitia Cousin
- 4CS, Laboratory Channels and Connexins in Cancers and Cell Stemness, CNRS UMR 6041, University of Poitiers, Poitiers, France
| | - Patricia Arnault
- 4CS, Laboratory Channels and Connexins in Cancers and Cell Stemness, CNRS UMR 6041, University of Poitiers, Poitiers, France
| | - Bruno Constantin
- 4CS, Laboratory Channels and Connexins in Cancers and Cell Stemness, CNRS UMR 6041, University of Poitiers, Poitiers, France
| | - Emmanuel Moyse
- University of Tours, INRAe Centre Val-de-Loire UMR-85, CNRS UMR-1247, Physiologie de la Reproduction et Comportements, Nouzilly, France
| | - Valérie Coronas
- 4CS, Laboratory Channels and Connexins in Cancers and Cell Stemness, CNRS UMR 6041, University of Poitiers, Poitiers, France
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Chen S, Xiao X, Song X, Qi Z, Li Y. Prediction of cord blood leptin on infant's neurodevelopment: A birth cohort in rural Yunnan, China. Psychoneuroendocrinology 2023; 148:105955. [PMID: 36442291 DOI: 10.1016/j.psyneuen.2022.105955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 09/17/2022] [Accepted: 10/17/2022] [Indexed: 11/07/2022]
Abstract
BACKGROUND Leptin, one of the peptide hormones secreted by adipocytes, plays a vital part in metabolism, but its role in early-life neurodevelopment remains poorly understood. METHODS We performed leptin analysis on 323 cord blood samples collected from a birth cohort in Yunnan rural area, China, and assessed infants' neurodevelopment at one year of age by the Bayley Scales of Infant and Toddler Development-Third Edition (BSID-III). Multiple linear regression and binary logistic regression models were used to explore the associations between cord blood leptin (CBL) concentrations and infants' neurodevelopment and the ability of CBL to predict the probabilities of infants' neurodevelopment delay. RESULTS Overall, 323 infants were included in this study. The median concentration of CBL was 4.7 ng/ml. The proportion of 1-year-old infants identified as being neurodevelopmental delayed was 34.5%, and delays in cognitive, language, and motor domains were 11.1%, 26.6%, and 13.9%, respectively. Multiple linear regression analyses manifested that the CBL concentration (log10-transformed) was positively correlated with the cognitive, language, and motor composite scores in infants, respectively (β = 7.76, 95%CI: 3.81-11.71; β = 6.73, 95%CI: 3.41-10.06; and β = 6.88, 95%CI: 3.48-10.29, respectively). Binary logistic regression analysis showed that compared with the higher, lower CBL (< 4.7 ng/ml) yielded a 1.41-fold increase in the risk of language development delay (OR = 2.41,95%CI: 1.42-4.09), a 1.49-fold higher risk of motor development delay (OR = 2.49, 95%CI: 1.25-4.96), and a 1.71-fold higher risk of neurodevelopment delay (OR = 2.71, 95%CI: 1.64-4.48) among infants. The prediction models showed that the probabilities of development delay in infants' language, motor, and neurodevelopment increased with the decline of CBL concentrations [rs = -0.63 (95% CI: -0.71, -0.56), rs = -0.46 (95% CI: -0.55, -0.38), rs = -0.55 (95% CI: -0.63, -0.46), respectively]. CONCLUSION The decline of CBL was associated with the decrease in infants' neurodevelopment scores at one year of age. CBL below 4.7 ng/ml may increase the risk of infants' neurodevelopment delay. The probabilities of infants' neurodevelopment delay increased with the decrease of CBL concentrations. CBL may be a predictor of the probability of children's neurodevelopment delay.
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Affiliation(s)
- Shuqi Chen
- School of Public Health, Kunming Medical University, Kunming, China; Ministry of Child Health, Longgang District Maternity & Child Healthcare Hospital of Shenzhen, Shenzhen, Guangdong, China
| | - Xia Xiao
- School of Public Health, Kunming Medical University, Kunming, China
| | - Xiaoxiao Song
- School of Public Health, Kunming Medical University, Kunming, China
| | - Zhiye Qi
- School of Public Health, Kunming Medical University, Kunming, China; Department of Pediatrics, First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
| | - Yan Li
- School of Public Health, Kunming Medical University, Kunming, China.
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Liu J, Lai F, Hou Y, Zheng R. Leptin signaling and leptin resistance. MEDICAL REVIEW (BERLIN, GERMANY) 2022; 2:363-384. [PMID: 37724323 PMCID: PMC10388810 DOI: 10.1515/mr-2022-0017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 07/12/2022] [Indexed: 09/20/2023]
Abstract
With the prevalence of obesity and associated comorbidities, studies aimed at revealing mechanisms that regulate energy homeostasis have gained increasing interest. In 1994, the cloning of leptin was a milestone in metabolic research. As an adipocytokine, leptin governs food intake and energy homeostasis through leptin receptors (LepR) in the brain. The failure of increased leptin levels to suppress feeding and elevate energy expenditure is referred to as leptin resistance, which encompasses complex pathophysiological processes. Within the brain, LepR-expressing neurons are distributed in hypothalamus and other brain areas, and each population of the LepR-expressing neurons may mediate particular aspects of leptin effects. In LepR-expressing neurons, the binding of leptin to LepR initiates multiple signaling cascades including janus kinase (JAK)-signal transducers and activators of transcription (STAT) phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT), extracellular regulated protein kinase (ERK), and AMP-activated protein kinase (AMPK) signaling, etc., mediating leptin actions. These findings place leptin at the intersection of metabolic and neuroendocrine regulations, and render leptin a key target for treating obesity and associated comorbidities. This review highlights the main discoveries that shaped the field of leptin for better understanding of the mechanism governing metabolic homeostasis, and guides the development of safe and effective interventions to treat obesity and associated diseases.
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Affiliation(s)
- Jiarui Liu
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
| | - Futing Lai
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
| | - Yujia Hou
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
| | - Ruimao Zheng
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
- Neuroscience Research Institute, Peking University, Beijing, China
- Key Laboratory for Neuroscience of Ministry of Education, Peking University, Beijing, China
- Key Laboratory for Neuroscience of National Health Commission, Peking University, Beijing 100191, China
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Watts AG, Kanoski SE, Sanchez-Watts G, Langhans W. The physiological control of eating: signals, neurons, and networks. Physiol Rev 2022; 102:689-813. [PMID: 34486393 PMCID: PMC8759974 DOI: 10.1152/physrev.00028.2020] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 08/30/2021] [Indexed: 02/07/2023] Open
Abstract
During the past 30 yr, investigating the physiology of eating behaviors has generated a truly vast literature. This is fueled in part by a dramatic increase in obesity and its comorbidities that has coincided with an ever increasing sophistication of genetically based manipulations. These techniques have produced results with a remarkable degree of cell specificity, particularly at the cell signaling level, and have played a lead role in advancing the field. However, putting these findings into a brain-wide context that connects physiological signals and neurons to behavior and somatic physiology requires a thorough consideration of neuronal connections: a field that has also seen an extraordinary technological revolution. Our goal is to present a comprehensive and balanced assessment of how physiological signals associated with energy homeostasis interact at many brain levels to control eating behaviors. A major theme is that these signals engage sets of interacting neural networks throughout the brain that are defined by specific neural connections. We begin by discussing some fundamental concepts, including ones that still engender vigorous debate, that provide the necessary frameworks for understanding how the brain controls meal initiation and termination. These include key word definitions, ATP availability as the pivotal regulated variable in energy homeostasis, neuropeptide signaling, homeostatic and hedonic eating, and meal structure. Within this context, we discuss network models of how key regions in the endbrain (or telencephalon), hypothalamus, hindbrain, medulla, vagus nerve, and spinal cord work together with the gastrointestinal tract to enable the complex motor events that permit animals to eat in diverse situations.
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Affiliation(s)
- Alan G Watts
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Scott E Kanoski
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Graciela Sanchez-Watts
- The Department of Biological Sciences, Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Wolfgang Langhans
- Physiology and Behavior Laboratory, Eidgenössische Technische Hochschule-Zürich, Schwerzenbach, Switzerland
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7
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Lutz TA. Creating the amylin story. Appetite 2022; 172:105965. [DOI: 10.1016/j.appet.2022.105965] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/28/2022] [Accepted: 02/04/2022] [Indexed: 02/07/2023]
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Jeong JK, Dow SA, Young CN. Sensory Circumventricular Organs, Neuroendocrine Control, and Metabolic Regulation. Metabolites 2021; 11:metabo11080494. [PMID: 34436435 PMCID: PMC8402088 DOI: 10.3390/metabo11080494] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/13/2021] [Accepted: 07/27/2021] [Indexed: 11/16/2022] Open
Abstract
The central nervous system is critical in metabolic regulation, and accumulating evidence points to a distributed network of brain regions involved in energy homeostasis. This is accomplished, in part, by integrating peripheral and central metabolic information and subsequently modulating neuroendocrine outputs through the paraventricular and supraoptic nucleus of the hypothalamus. However, these hypothalamic nuclei are generally protected by a blood-brain-barrier limiting their ability to directly sense circulating metabolic signals—pointing to possible involvement of upstream brain nuclei. In this regard, sensory circumventricular organs (CVOs), brain sites traditionally recognized in thirst/fluid and cardiovascular regulation, are emerging as potential sites through which circulating metabolic substances influence neuroendocrine control. The sensory CVOs, including the subfornical organ, organum vasculosum of the lamina terminalis, and area postrema, are located outside the blood-brain-barrier, possess cellular machinery to sense the metabolic interior milieu, and establish complex neural networks to hypothalamic neuroendocrine nuclei. Here, evidence for a potential role of sensory CVO-hypothalamic neuroendocrine networks in energy homeostasis is presented.
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Affiliation(s)
| | | | - Colin N. Young
- Correspondence: ; Tel.: +1-202-994-9575; Fax: +1-202-994-287
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Foll CL, Lutz TA. Systemic and Central Amylin, Amylin Receptor Signaling, and Their Physiological and Pathophysiological Roles in Metabolism. Compr Physiol 2020; 10:811-837. [PMID: 32941692 DOI: 10.1002/cphy.c190034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This article in the Neural and Endocrine Section of Comprehensive Physiology discusses the physiology and pathophysiology of the pancreatic hormone amylin. Shortly after its discovery in 1986, amylin has been shown to reduce food intake as a satiation signal to limit meal size. Amylin also affects food reward, sensitizes the brain to the catabolic actions of leptin, and may also play a prominent role in the development of certain brain areas that are involved in metabolic control. Amylin may act at different sites in the brain in addition to the area postrema (AP) in the caudal hindbrain. In particular, the sensitizing effect of amylin on leptin action may depend on a direct interaction in the hypothalamus. The concept of central pathways mediating amylin action became more complex after the discovery that amylin is also synthesized in certain hypothalamic areas but the interaction between central and peripheral amylin signaling remains currently unexplored. Amylin may also play a dominant pathophysiological role that is associated with the aggregation of monomeric amylin into larger, cytotoxic molecular entities. This aggregation in certain species may contribute to the development of type 2 diabetes mellitus but also cardiovascular disease. Amylin receptor pharmacology is complex because several distinct amylin receptor subtypes have been described, because other neuropeptides [e.g., calcitonin gene-related peptide (CGRP)] can also bind to amylin receptors, and because some components of the functional amylin receptor are also used for other G-protein coupled receptor (GPCR) systems. © 2020 American Physiological Society. Compr Physiol 10:811-837, 2020.
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Affiliation(s)
- Christelle Le Foll
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
| | - Thomas A Lutz
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
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10
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Picone P, Di Carlo M, Nuzzo D. Obesity and Alzheimer’s disease: Molecular bases. Eur J Neurosci 2020; 52:3944-3950. [DOI: 10.1111/ejn.14758] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 04/15/2020] [Accepted: 04/16/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Pasquale Picone
- Consiglio Nazionale delle Ricerche Istituto per la Ricerca e l’Innovazione Biomedica (CNR‐IRIB) Palermo Italy
| | - Marta Di Carlo
- Consiglio Nazionale delle Ricerche Istituto per la Ricerca e l’Innovazione Biomedica (CNR‐IRIB) Palermo Italy
| | - Domenico Nuzzo
- Consiglio Nazionale delle Ricerche Istituto per la Ricerca e l’Innovazione Biomedica (CNR‐IRIB) Palermo Italy
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Zakariassen HL, John LM, Lutz TA. Central control of energy balance by amylin and calcitonin receptor agonists and their potential for treatment of metabolic diseases. Basic Clin Pharmacol Toxicol 2020; 127:163-177. [PMID: 32363722 DOI: 10.1111/bcpt.13427] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/28/2020] [Accepted: 04/28/2020] [Indexed: 12/13/2022]
Abstract
The prevalence of obesity and associated comorbidities such as type 2 diabetes and cardiovascular disease is increasing globally. Body-weight loss reduces the risk of morbidity and mortality in obese individuals, and thus, pharmacotherapies that induce weight loss can be of great value in improving the health and well-being of people living with obesity. Treatment with amylin and calcitonin receptor agonists reduces food intake and induces weight loss in several animal models, and a number of companies have started clinical testing for peptide analogues in the treatment of obesity and/or type 2 diabetes. Studies predominantly performed in rodent models show that amylin and the dual amylin/calcitonin receptor agonist salmon calcitonin achieve their metabolic effects by engaging areas in the brain associated with regulating homeostatic energy balance. In particular, signalling via neuronal circuits in the caudal hindbrain and the hypothalamus is implicated in mediating effects on food intake and energy expenditure. We review the current literature investigating the interaction of amylin/calcitonin receptor agonists with neurocircuits that induce the observed metabolic effects. Moreover, the status of drug development of amylin and calcitonin receptor agonists for the treatment of metabolic diseases is summarized.
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Affiliation(s)
- Hannah Louise Zakariassen
- Section of Experimental Animal Models, Department of Veterinary and Animal Science, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark.,Obesity Pharmacology, Novo Nordisk A/S, Måløv, Denmark
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12
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Boyle CN, Le Foll C. Amylin and Leptin interaction: Role During Pregnancy, Lactation and Neonatal Development. Neuroscience 2019; 447:136-147. [PMID: 31846753 DOI: 10.1016/j.neuroscience.2019.11.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Revised: 11/08/2019] [Accepted: 11/21/2019] [Indexed: 01/04/2023]
Abstract
Amylin is co-secreted with insulin by pancreatic β-cells in response to a meal and produced by neurons in discrete hypothalamic brain areas. Leptin is proportionally secreted by the adipose tissue. Both hormones control food intake and energy homeostasis post-weaning in rodents. While amylin's main site of action is located in the area postrema (AP) and leptin's is located in the mediobasal hypothalamus, both hormones can also influence the other's signaling pathway; amylin has been shown enhance hypothalamic leptin signaling, and amylin signaling in the AP may rely on functional leptin receptors to modulate its effects. These two hormones also play major roles during other life periods. During pregnancy, leptin levels rise as a result of an increase in fat depot resulting in gestational leptin-resistance to prepare the maternal body for the metabolic needs during fetal development. The role of amylin is far less studied during pregnancy and lactation, though amylin levels seem to be elevated during pregnancy relative to insulin. Whether amylin and leptin interact during pregnancy and lactation remains to be assessed. Lastly, during brain development, amylin and leptin are major regulators of cell birth during embryogenesis and act as neurotrophic factors in the neonatal period. This review will highlight the role of amylin and leptin, and their possible interaction, during these dynamic time periods of pregnancy, lactation, and early development.
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Affiliation(s)
- Christina N Boyle
- Institute of Veterinary Physiology, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
| | - Christelle Le Foll
- Institute of Veterinary Physiology, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
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13
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Sarnat HB, Flores-Sarnat L, Boltshauser E. Area Postrema: Fetal Maturation, Tumors, Vomiting Center, Growth, Role in Neuromyelitis Optica. Pediatr Neurol 2019; 94:21-31. [PMID: 30797593 DOI: 10.1016/j.pediatrneurol.2018.12.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 12/12/2018] [Accepted: 12/17/2018] [Indexed: 01/17/2023]
Abstract
INTRODUCTION The area postrema in the caudal fourth ventricular floor is highly vascular without blood-brain or blood-cerebrospinal fluid barrier. In addition to its function as vomiting center, several others are part of the circumventricular organs for vasomotor/angiotensin II regulation, role in neuromyelitis optica related to aquaporin-4, and somatic growth and appetite regulation. Functions are immature at birth. The purpose was to demonstrate neuronal, synaptic, glial, or ependymal maturation in the area postrema of normal fetuses. We describe three area postrema tumors. METHODS Sections of caudal fourth ventricle of 12 normal human fetal brains at autopsy aged six to 40 weeks and three infants aged three to 18 months were examined. Immunocytochemical neuronal and glial markers were applied to paraffin sections. Two infants with area postrema tumors and another with neurocutaneous melanocytosis and pernicious vomiting also studied. RESULTS Area postrema neurons exhibited cytologic maturity and synaptic circuitry by 14 weeks'. Astrocytes coexpressed vimentin, glial fibrillary acidic protein, and S-100β protein. The ependyma is thin over area postrema, with fetal ependymocytic basal processes. A glial layer separates area postrema from medullary tegmentum. Melanocytes infiltrated area postrema in the toddler with pernicious vomiting; two children had primary area postrema pilocytic astrocytomas. CONCLUSIONS Although area postrema is cytologically mature by 14 weeks, growth increases and functions mature during postnatal months. We recommend neuroimaging for patients with unexplained vomiting and that area postrema neuropathology includes synaptophysin and microtubule-associated protein-2 in patients with suspected dysfunction.
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Affiliation(s)
- Harvey B Sarnat
- Departments of Paediatrics, University of Calgary Cumming School of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada; Pathology (Neuropathology), University of Calgary Cumming School of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada; Clinical Neurosciences, University of Calgary Cumming School of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada.
| | - Laura Flores-Sarnat
- Departments of Paediatrics, University of Calgary Cumming School of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada; Clinical Neurosciences, University of Calgary Cumming School of Medicine and Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Eugen Boltshauser
- Department of Paediatric Neurology, Children's University Hospital, Zürich, Switzerland
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Wee NKY, Lorenz MR, Bekirov Y, Jacquin MF, Scheller EL. Shared Autonomic Pathways Connect Bone Marrow and Peripheral Adipose Tissues Across the Central Neuraxis. Front Endocrinol (Lausanne) 2019; 10:668. [PMID: 31611846 PMCID: PMC6776593 DOI: 10.3389/fendo.2019.00668] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 09/16/2019] [Indexed: 12/31/2022] Open
Abstract
Bone marrow adipose tissue (BMAT) is increased in both obesity and anorexia. This is unique relative to white adipose tissue (WAT), which is generally more attuned to metabolic demand. It suggests that there may be regulatory pathways that are common to both BMAT and WAT and also those that are specific to BMAT alone. The central nervous system (CNS) is a key mediator of adipose tissue function through sympathetic adrenergic neurons. Thus, we hypothesized that central autonomic pathways may be involved in BMAT regulation. To test this, we first quantified the innervation of BMAT by tyrosine hydroxylase (TH) positive nerves within the metaphysis and diaphysis of the tibia of B6 and C3H mice. We found that many of the TH+ axons were concentrated around central blood vessels in the bone marrow. However, there were also areas of free nerve endings which terminated in regions of BMAT adipocytes. Overall, the proportion of nerve-associated BMAT adipocytes increased from proximal to distal along the length of the tibia (from ~3-5 to ~14-24%), regardless of mouse strain. To identify the central pathways involved in BMAT innervation and compare to peripheral WAT, we then performed retrograde viral tract tracing with an attenuated pseudorabies virus (PRV) to infect efferent nerves from the tibial metaphysis (inclusive of BMAT) and inguinal WAT (iWAT) of C3H mice. PRV positive neurons were identified consistently from both injection sites in the intermediolateral horn of the spinal cord, reticular formation, rostroventral medulla, solitary tract, periaqueductal gray, locus coeruleus, subcoeruleus, Barrington's nucleus, and hypothalamus. We also observed dual-PRV infected neurons within the majority of these regions. Similar tracings were observed in pons, midbrain, and hypothalamic regions from B6 femur and tibia, demonstrating that these results persist across mouse strains and between skeletal sites. Altogether, this is the first quantitative report of BMAT autonomic innervation and reveals common central neuroanatomic pathways, including putative "command" neurons, involved in coordinating multiple aspects of sympathetic output and facilitation of parallel processing between bone marrow/BMAT and peripheral adipose tissue.
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Affiliation(s)
- Natalie K. Y. Wee
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, United States
- Department of Reconstructive Sciences, UConn Health, Farmington, CT, United States
| | - Madelyn R. Lorenz
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, United States
| | - Yusuf Bekirov
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, United States
| | - Mark F. Jacquin
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, United States
| | - Erica L. Scheller
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, United States
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, United States
- *Correspondence: Erica L. Scheller
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15
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Duffy S, Lutz TA, Boyle CN. Rodent models of leptin receptor deficiency are less sensitive to amylin. Am J Physiol Regul Integr Comp Physiol 2018; 315:R856-R865. [DOI: 10.1152/ajpregu.00179.2018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The pancreatic hormone amylin is released from beta cells following nutrient ingestion and contributes to the control of body weight and glucose homeostasis. Amylin reduces food intake by activating neurons in the area postrema (AP). Amylin was also shown to synergize with the adipokine leptin, with combination therapy producing greater weight loss and food intake reduction than either hormone alone. Although amylin and leptin were initially thought to interact downstream of the AP in the hypothalamus, recent findings show that the two hormones can act on the same AP neurons, suggesting a more direct relationship. The objective of this study was to determine whether amylin action depends on functional leptin signaling. We tested the ability of amylin to induce satiation and to activate its primary target neurons in the AP in two rodent models of LepR deficiency, the db/db mouse and the Zucker diabetic fatty (ZDF) rat. When compared with wild-type (WT) mice, db/db mice exhibited reduced amylin-induced satiation, reduced amylin-induced Fos in the AP, and a lower expression of calcitonin receptor (CTR) protein, the core component of all amylin receptors. ZDF rats also showed no reduction in food intake following amylin treatment; however, unlike the db/db mice, levels of amylin-induced Fos and CTR in the AP were no different than WT rats. Our results suggest that LepR expression is required for the full anorexic effect of amylin; however, the neuronal activation in the AP seems to depend on the type of LepR mutation.
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Affiliation(s)
- Sonya Duffy
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
| | - Thomas A. Lutz
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
- Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Christina N. Boyle
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
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16
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Samson WK. Editorial team changes in 2018. Am J Physiol Regul Integr Comp Physiol 2017; 313:R631-R632. [DOI: 10.1152/ajpregu.00385.2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 10/27/2017] [Accepted: 10/27/2017] [Indexed: 11/22/2022]
Affiliation(s)
- Willis K. Samson
- Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, Missouri
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17
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Guillebaud F, Girardet C, Abysique A, Gaigé S, Barbouche R, Verneuil J, Jean A, Leprince J, Tonon MC, Dallaporta M, Lebrun B, Troadec JD. Glial Endozepines Inhibit Feeding-Related Autonomic Functions by Acting at the Brainstem Level. Front Neurosci 2017; 11:308. [PMID: 28611581 PMCID: PMC5447764 DOI: 10.3389/fnins.2017.00308] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 05/16/2017] [Indexed: 01/05/2023] Open
Abstract
Endozepines are endogenous ligands for the benzodiazepine receptors and also target a still unidentified GPCR. The endozepine octadecaneuropeptide (ODN), an endoproteolytic processing product of the diazepam-binding inhibitor (DBI) was recently shown to be involved in food intake control as an anorexigenic factor through ODN-GPCR signaling and mobilization of the melanocortinergic signaling pathway. Within the hypothalamus, the DBI gene is mainly expressed by non-neuronal cells such as ependymocytes, tanycytes, and protoplasmic astrocytes, at levels depending on the nutritional status. Administration of ODN C-terminal octapeptide (OP) in the arcuate nucleus strongly reduces food intake. Up to now, the relevance of extrahypothalamic targets for endozepine signaling-mediated anorexia has been largely ignored. We focused our study on the dorsal vagal complex located in the caudal brainstem. This structure is strongly involved in the homeostatic control of food intake and comprises structural similarities with the hypothalamus. In particular, a circumventricular organ, the area postrema (AP) and a tanycyte-like cells forming barrier between the AP and the adjacent nucleus tractus solitarius (NTS) are present. We show here that DBI is highly expressed by ependymocytes lining the fourth ventricle, tanycytes-like cells, as well as by proteoplasmic astrocytes located in the vicinity of AP/NTS interface. ODN staining observed at the electron microscopic level reveals that ODN-expressing tanycyte-like cells and protoplasmic astrocytes are sometimes found in close apposition to neuronal elements such as dendritic profiles or axon terminals. Intracerebroventricular injection of ODN or OP in the fourth ventricle triggers c-Fos activation in the dorsal vagal complex and strongly reduces food intake. We also show that, similarly to leptin, ODN inhibits the swallowing reflex when microinjected into the swallowing pattern generator located in the NTS. In conclusion, we hypothesized that ODN expressing cells located at the AP/NTS interface could release ODN and modify excitability of NTS neurocircuitries involved in food intake control.
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Affiliation(s)
- Florent Guillebaud
- Laboratoire Physiologie et Physiopathologie du Système Nerveux Somato-Moteur et Neurovégétatif EA 4674, Faculté des Sciences et Techniques de St Jérôme, Université Aix-MarseilleMarseille, France
| | - Clémence Girardet
- Laboratoire Physiologie et Physiopathologie du Système Nerveux Somato-Moteur et Neurovégétatif EA 4674, Faculté des Sciences et Techniques de St Jérôme, Université Aix-MarseilleMarseille, France
| | - Anne Abysique
- Laboratoire Physiologie et Physiopathologie du Système Nerveux Somato-Moteur et Neurovégétatif EA 4674, Faculté des Sciences et Techniques de St Jérôme, Université Aix-MarseilleMarseille, France
| | - Stéphanie Gaigé
- Laboratoire Physiologie et Physiopathologie du Système Nerveux Somato-Moteur et Neurovégétatif EA 4674, Faculté des Sciences et Techniques de St Jérôme, Université Aix-MarseilleMarseille, France
| | - Rym Barbouche
- Laboratoire Physiologie et Physiopathologie du Système Nerveux Somato-Moteur et Neurovégétatif EA 4674, Faculté des Sciences et Techniques de St Jérôme, Université Aix-MarseilleMarseille, France
| | - Jérémy Verneuil
- Laboratoire Physiologie et Physiopathologie du Système Nerveux Somato-Moteur et Neurovégétatif EA 4674, Faculté des Sciences et Techniques de St Jérôme, Université Aix-MarseilleMarseille, France
| | - André Jean
- Laboratoire Physiologie et Physiopathologie du Système Nerveux Somato-Moteur et Neurovégétatif EA 4674, Faculté des Sciences et Techniques de St Jérôme, Université Aix-MarseilleMarseille, France
| | - Jérôme Leprince
- Institut National de la Santé et de la Recherche Médicale U1239, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Institute for Research and Innovation in Biomedicine, University of Rouen NormadieMont-Saint-Aignan, France
| | - Marie-Christine Tonon
- Institut National de la Santé et de la Recherche Médicale U1239, Laboratory of Neuronal and Neuroendocrine Communication and Differentiation, Institute for Research and Innovation in Biomedicine, University of Rouen NormadieMont-Saint-Aignan, France
| | - Michel Dallaporta
- Laboratoire Physiologie et Physiopathologie du Système Nerveux Somato-Moteur et Neurovégétatif EA 4674, Faculté des Sciences et Techniques de St Jérôme, Université Aix-MarseilleMarseille, France
| | - Bruno Lebrun
- Laboratoire Physiologie et Physiopathologie du Système Nerveux Somato-Moteur et Neurovégétatif EA 4674, Faculté des Sciences et Techniques de St Jérôme, Université Aix-MarseilleMarseille, France
| | - Jean-Denis Troadec
- Laboratoire Physiologie et Physiopathologie du Système Nerveux Somato-Moteur et Neurovégétatif EA 4674, Faculté des Sciences et Techniques de St Jérôme, Université Aix-MarseilleMarseille, France
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Levin BE, Lutz TA. Amylin and Leptin: Co-Regulators of Energy Homeostasis and Neuronal Development. Trends Endocrinol Metab 2017; 28:153-164. [PMID: 27938937 DOI: 10.1016/j.tem.2016.11.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 11/03/2016] [Accepted: 11/07/2016] [Indexed: 12/18/2022]
Abstract
While the regulation of energy homeostasis by amylin is already well-characterized, emerging data suggest that amylin is also crucial for the development of neural pathways in the hypothalamus and caudal hindbrain (area postrema, AP; nucleus tractus solitarius, NTS). Exciting new findings demonstrate crucial amylin-leptin interactions in altering the activity of specific hypothalamic and AP neurons, and a role for amylin as a novel class of 'leptin sensitizers' which enhance leptin signaling in both leptin-sensitive and -resistant individuals, in part by stimulating IL-6 production by hypothalamic microglia. This review summarizes these findings and provides a hypothetical framework for future studies to elucidate the mechanisms by which amylin and leptin act individually and as co-conspirators to alter energy homeostasis and neuronal development.
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Affiliation(s)
- Barry E Levin
- Department of Neurology, Rutgers, New Jersey Medical School, Newark, NJ 07103, USA.
| | - Thomas A Lutz
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland
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19
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Johnson MD, Bouret SG, Dunn-Meynell AA, Boyle CN, Lutz TA, Levin BE. Early postnatal amylin treatment enhances hypothalamic leptin signaling and neural development in the selectively bred diet-induced obese rat. Am J Physiol Regul Integr Comp Physiol 2016; 311:R1032-R1044. [PMID: 27629888 PMCID: PMC5256974 DOI: 10.1152/ajpregu.00326.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/02/2016] [Accepted: 09/02/2016] [Indexed: 12/25/2022]
Abstract
Selectively bred diet-induced obese (DIO) rats become obese on a high-fat diet and are leptin resistant before becoming obese. Compared with diet-resistant (DR) neonates, DIO neonates have impaired leptin-dependent arcuate (ARC) neuropeptide Y/agouti-related peptide (NPY/AgRP) and α-melanocyte-stimulating hormone (α-MSH; from proopiomelanocortin (POMC) neurons) axon outgrowth to the paraventricular nucleus (PVN). Using phosphorylation of STAT3 (pSTAT3) as a surrogate, we show that reduced DIO ARC leptin signaling develops by postnatal day 7 (P7) and is reduced within POMC but not NPY/AgRP neurons. Since amylin increases leptin signaling in adult rats, we treated DIO neonates with amylin during postnatal hypothalamic development and assessed leptin signaling, leptin-dependent ARC-PVN pathway development, and metabolic changes. DIO neonates treated with amylin from P0-6 and from P0-16 increased ARC leptin signaling and both AgRP and α-MSH ARC-PVN pathway development, but increased only POMC neuron number. Despite ARC-PVN pathway correction, P0-16 amylin-induced reductions in body weight did not persist beyond treatment cessation. Since amylin enhances adult DIO ARC signaling via an IL-6-dependent mechanism, we assessed ARC-PVN pathway competency in IL-6 knockout mice and found that the AgRP, but not the α-MSH, ARC-PVN pathway was reduced. These results suggest that both leptin and amylin are important neurotrophic factors for the postnatal development of the ARC-PVN pathway. Amylin might act as a direct neurotrophic factor in DIO rats to enhance both the number of POMC neurons and their α-MSH ARC-PVN pathway development. This suggests important and selective roles for amylin during ARC hypothalamic development.
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Affiliation(s)
- Miranda D Johnson
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sebastien G Bouret
- The Saban Research Institute, Developmental Neuroscience Program, Children's Hospital Los Angeles, University of Southern California, Los Angeles, California.,INSERM, Jean-Pierre Aubert Research Center, Lille, France
| | | | - Christina N Boyle
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland; and
| | - Thomas A Lutz
- Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland; and
| | - Barry E Levin
- Department of Neurology, Rutgers New Jersey Medical School, Newark, New Jersey
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20
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Trevaskis JL, Wittmer C, Athanacio J, Griffin PS, Parkes DG, Roth JD. Amylin/leptin synergy is absent in extreme obesity and not restored by calorie restriction-induced weight loss in rats. Obes Sci Pract 2016; 2:385-391. [PMID: 28090343 PMCID: PMC5192543 DOI: 10.1002/osp4.62] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 07/15/2016] [Accepted: 07/23/2016] [Indexed: 02/05/2023] Open
Abstract
Objective Co‐administration of amylin and leptin induces synergistic and clinically meaningful (>10%) weight loss that is attenuated as the degree of obesity increases. We explored whether calorie restriction (CR) could restore amylin/leptin synergy in very obese rats. Methods Sprague Dawley rats on high‐fat diet (696 ± 8 g, n = 72) were randomized to three cohorts (C1–C3). Rats in C1 were administered vehicle, rat amylin (50 µg kg−1 d−1), murine leptin (125 µg kg−1 d−1) or amylin and leptin for 28 days (n = 6 per group) via subcutaneous minipump. Simultaneously, C2 and C3 rats initiated CR. After moderate (12.4 ± 0.3%, 86.7 ± 2.8 g; C2) or severe (24.9 ± 0.3%, 172.7 ± 4.7 g; C3) weight loss, amylin and/or leptin was administered as described. Results In C1, leptin did not alter weight, and amylin induced 40.2 ± 6.1 g weight loss (−6.0 ± 0.9%), which was not enhanced by leptin (44.4 ± 4.9 g, −6.1 ± 0.8%). In C2, vehicle‐treated (75.1 ± 7.8 g weight change from start of treatment, 1.1 ± 0.8% difference from start of pre‐CR phase) and leptin‐treated rats (68.6 ± 9.2 g, −1.3 ± 1.0%) rebounded to pre‐restriction weight that was attenuated by amylin (29.2 ± 11.4 g, −6.2 ± 0.7%). Leptin did not enhance the effect of amylin (22.8 ± 11.7 g, −8.3 ± 1.5%). In C3, vehicle‐treated and leptin‐treated rats regained most of their weight (161.9 ± 11.8, −2.3 ± 0.8% and 144.6 ± 9.5 g, −2.3 ± 0.9%, respectively), which was attenuated by amylin (91.1 ± 16.8 g, −11.2 ± 0.7%), but not enhanced by leptin (83.0 ± 7.6 g, −10.7 ± 0.8%). Conclusions Extreme obesity associated with leptin resistance perturbs amylin/leptin weight loss synergy in rats, which cannot be restored by pre‐treatment weight loss.
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Affiliation(s)
| | - C Wittmer
- Amylin Pharmaceuticals San Diego CA USA
| | | | | | | | - J D Roth
- Present address: Intercept Pharmaceuticals San Diego CA USA
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Liberini CG, Boyle CN, Cifani C, Venniro M, Hope BT, Lutz TA. Amylin receptor components and the leptin receptor are co-expressed in single rat area postrema neurons. Eur J Neurosci 2016; 43:653-61. [PMID: 26750109 PMCID: PMC10704335 DOI: 10.1111/ejn.13163] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 12/17/2015] [Accepted: 12/22/2015] [Indexed: 12/16/2023]
Abstract
Amylin is a pancreatic β-cell hormone that acts as a satiating signal to inhibit food intake by binding to amylin receptors (AMYs) and activating a specific neuronal population in the area postrema (AP). AMYs are heterodimers that include a calcitonin receptor (CTR) subunit [CTR isoform a or b (CTRa or CTRb)] and a member of the receptor activity-modifying proteins (RAMPs). Here, we used single-cell quantitative polymerase chain reaction to assess co-expression of AMY subunits in AP neurons from rats that were injected with amylin or vehicle. Because amylin interacts synergistically with the adipokine leptin to reduce body weight, we also assessed the co-expression of AMY and the leptin receptor isoform b (LepRb) in amylin-activated AP neurons. Single cells were collected from Wistar rats and from transgenic Fos-GFP rats that express green fluorescent protein (GFP) under the control of the Fos promoter. We found that the mRNAs of CTRa, RAMP1, RAMP2 and RAMP3 were all co-expressed in single AP neurons. Moreover, most of the CTRa+ cells co-expressed more than one of the RAMPs. Amylin down-regulated RAMP1 and RAMP3 but not CTR mRNAs in AMY+ neurons, suggesting a possible negative feedback mechanism of amylin at its own primary receptors. Interestingly, amylin up-regulated RAMP2 mRNA. We also found that a high percentage of single cells that co-expressed all components of a functional AMY expressed LepRb mRNA. Thus, single AP cells expressed both AMY and LepRb, which formed a population of first-order neurons that presumably can be directly activated by amylin and, at least in part, also by leptin.
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Affiliation(s)
- Claudia G. Liberini
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich (UZH), Zurich, Switzerland
- Zurich Centre for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Zurich Centre for Clinical Studies, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
| | - Christina Neuner Boyle
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich (UZH), Zurich, Switzerland
| | - Carlo Cifani
- School of Pharmacy, Pharmacology Unit, University of Camerino, Italy
- Intramural Research Program, National Institutes of Health/National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Marco Venniro
- Intramural Research Program, National Institutes of Health/National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Bruce T. Hope
- Intramural Research Program, National Institutes of Health/National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Thomas A. Lutz
- Institute of Veterinary Physiology, Vetsuisse Faculty University of Zurich (UZH), Zurich, Switzerland
- Zurich Centre for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
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