1
|
Wee RWS, Mishchanchuk K, AlSubaie R, Church TW, Gold MG, MacAskill AF. Internal-state-dependent control of feeding behavior via hippocampal ghrelin signaling. Neuron 2024; 112:288-305.e7. [PMID: 37977151 DOI: 10.1016/j.neuron.2023.10.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/13/2023] [Accepted: 10/12/2023] [Indexed: 11/19/2023]
Abstract
Hunger is an internal state that not only invigorates feeding but also acts as a contextual cue for higher-order control of anticipatory feeding-related behavior. The ventral hippocampus is crucial for differentiating optimal behavior across contexts, but how internal contexts such as hunger influence hippocampal circuitry is unknown. In this study, we investigated the role of the ventral hippocampus during feeding behavior across different states of hunger in mice. We found that activity of a unique subpopulation of neurons that project to the nucleus accumbens (vS-NAc neurons) increased when animals investigated food, and this activity inhibited the transition to begin eating. Increases in the level of the peripheral hunger hormone ghrelin reduced vS-NAc activity during this anticipatory phase of feeding via ghrelin-receptor-dependent increases in postsynaptic inhibition and promoted the initiation of eating. Together, these experiments define a ghrelin-sensitive hippocampal circuit that informs the decision to eat based on internal state.
Collapse
Affiliation(s)
- Ryan W S Wee
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, UK
| | - Karyna Mishchanchuk
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, UK
| | - Rawan AlSubaie
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, UK
| | - Timothy W Church
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, UK
| | - Matthew G Gold
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, UK
| | - Andrew F MacAskill
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, UK.
| |
Collapse
|
2
|
Barrile F, Cassano D, Fernandez G, De Francesco PN, Reynaldo M, Cantel S, Fehrentz JA, Donato J, Schiöth HB, Zigman JM, Perello M. Ghrelin's orexigenic action in the lateral hypothalamic area involves indirect recruitment of orexin neurons and arcuate nucleus activation. Psychoneuroendocrinology 2023; 156:106333. [PMID: 37454647 PMCID: PMC10530520 DOI: 10.1016/j.psyneuen.2023.106333] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/30/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
OBJECTIVE Ghrelin is a potent orexigenic hormone, and the lateral hypothalamic area (LHA) has been suggested as a putative target mediating ghrelin's effects on food intake. Here, we aimed to investigate the presence of neurons expressing ghrelin receptor (a.k.a. growth hormone secretagogue receptor, GHSR) in the mouse LHA (LHAGHSR neurons), its physiological implications and the neuronal circuit recruited by local ghrelin action. METHODS We investigated the distribution of LHAGHSR neurons using different histologic strategies, including the use of a reporter mice expressing enhanced green fluorescent protein under the control of the GHSR promoter. Also, we investigated the physiological implications of local injections of ghrelin within the LHA, and the extent to which the orexigenic effect of intra-LHA-injected ghrelin involves the arcuate nucleus (ARH) and orexin neurons of the LHA (LHAorexin neurons) RESULTS: We found that: 1) LHAGHSR neurons are homogeneously distributed throughout the entire LHA; 2) intra-LHA injections of ghrelin transiently increase food intake and locomotor activity; 3) ghrelin's orexigenic effect in the LHA involves the indirect recruitment of LHAorexin neurons and the activation of ARH neurons; and 4) LHAGHSR neurons are not targeted by plasma ghrelin. CONCLUSIONS We provide a compelling neuroanatomical and functional characterization of LHAGHSR neurons in male mice that indicates that LHAGHSR cells are part of a hypothalamic neuronal circuit that potently induces food intake.
Collapse
Affiliation(s)
- Franco Barrile
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], La Plata, Buenos Aires, Argentina
| | - Daniela Cassano
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], La Plata, Buenos Aires, Argentina
| | - Gimena Fernandez
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], La Plata, Buenos Aires, Argentina
| | - Pablo N De Francesco
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], La Plata, Buenos Aires, Argentina
| | - Mirta Reynaldo
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], La Plata, Buenos Aires, Argentina
| | - Sonia Cantel
- Institut des Biomolécules Max Mousseron, Univ Montpellier, CNRS, ENSCM, Montpellier, France
| | - Jean-Alain Fehrentz
- Institut des Biomolécules Max Mousseron, Univ Montpellier, CNRS, ENSCM, Montpellier, France
| | - José Donato
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de São Paulo, São Paulo, Brazil
| | - Helgi B Schiöth
- Department of Surgical Sciences, Functional Pharmacology and Neuroscience, University of Uppsala, Uppsala, Sweden
| | - Jeffrey M Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, USA
| | - Mario Perello
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA), National University of La Plata], La Plata, Buenos Aires, Argentina; Department of Surgical Sciences, Functional Pharmacology and Neuroscience, University of Uppsala, Uppsala, Sweden.
| |
Collapse
|
3
|
Hirono M, Nakata M. Ghrelin signaling in the cerebellar cortex enhances GABAergic transmission onto Purkinje cells. Sci Rep 2023; 13:2150. [PMID: 36750743 PMCID: PMC9905081 DOI: 10.1038/s41598-023-29226-3] [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: 08/16/2022] [Accepted: 01/31/2023] [Indexed: 02/09/2023] Open
Abstract
Ghrelin, an orexigenic peptide ligand for growth hormone secretagogue receptor 1a (GHS-R1a), occurs not only in the stomach but also in the brain, and modulates neuronal activity and synaptic efficacy. Previous studies showed that GHS-R1a exists in the cerebellum, and ghrelin facilitates spontaneous firing of Purkinje cells (PCs). However, the effects of ghrelin on cerebellar GABAergic transmission have yet to be elucidated. We found that ghrelin enhanced GABAergic transmission between molecular layer interneurons (MLIs) and PCs using electrophysiological recordings in mouse cerebellar slices. This finding was consistent with the possibility that blocking synaptic transmission enhanced the ghrelin-induced facilitation of PC firing. Ghrelin profoundly increased the frequency of spontaneous inhibitory postsynaptic currents (IPSCs) in PCs without affecting miniature or stimulation-evoked IPSCs, whereas it significantly facilitated spontaneous firing of MLIs. This facilitation of MLI spiking disappeared during treatments with blockers of GHS-R1a, type 1 transient receptor potential canonical (TRPC1) channels and KCNQ channels. These results suggest that both activating TRPC1 channels and inhibiting KCNQ channels occur downstream the ghrelin-GHS-R1a signaling pathway probably in somatodendritic sites of MLIs. Thus, ghrelin can control PC firing directly and indirectly via its modulation of GABAergic transmission, thereby impacting activity in cerebellar circuitry.
Collapse
Affiliation(s)
- Moritoshi Hirono
- Department of Physiology, Wakayama Medical University, 811-1 Kimiidera, Wakayama, Wakayama, 641-8509, Japan.
| | - Masanori Nakata
- Department of Physiology, Wakayama Medical University, 811-1 Kimiidera, Wakayama, Wakayama, 641-8509, Japan
| |
Collapse
|
4
|
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: 45] [Impact Index Per Article: 22.5] [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.
Collapse
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
| |
Collapse
|
5
|
Ghrelin Regulates Expression of the Transcription Factor Pax6 in Hypoxic Brain Progenitor Cells and Neurons. Cells 2022; 11:cells11050782. [PMID: 35269403 PMCID: PMC8909042 DOI: 10.3390/cells11050782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 02/18/2022] [Accepted: 02/22/2022] [Indexed: 12/04/2022] Open
Abstract
The nature of brain impairment after hypoxia is complex and recovery harnesses different mechanisms, including neuroprotection and neurogenesis. Experimental evidence suggests that hypoxia may trigger neurogenesis postnatally by influencing the expression of a variety of transcription factors. However, the existing data are controversial. As a proof-of-principle, we subjected cultured cerebral cortex neurons, cerebellar granule neurons and organotypic cerebral cortex slices from rat brains to hypoxia and treated these cultures with the hormone ghrelin, which is well-known for its neuroprotective functions. We found that hypoxia elevated the expression levels and stimulated nuclear translocation of ghrelin’s receptor GHSR1 in the cultured neurons and the acute organotypic slices, whereas ghrelin treatment reduced the receptor expression to normoxic levels. GHSR1 expression was also increased in cerebral cortex neurons of mice with induced experimental stroke. Additional quantitative analyses of immunostainings for neuronal proliferation and differentiation markers revealed that hypoxia stimulated the proliferation of neuronal progenitors, whereas ghrelin application during the phase of recovery from hypoxia counteracted these effects. At the mechanistic level, we provide a link between the described post-ischemic phenomena and the expression of the transcription factor Pax6, an important regulator of neural progenitor cell fate. In contrast to the neurogenic niches in the brain where hypoxia is known to increase Pax6 expression, the levels of the transcription factor in cultured hypoxic cerebral cortex cells were downregulated. Moreover, the application of ghrelin to hypoxic neurons normalised the expression levels of these factors. Our findings suggest that ghrelin stimulates neurogenic factors for the protection of neurons in a GHSR1-dependent manner in non-neurogenic brain areas such as the cerebral cortex after exposure to hypoxia.
Collapse
|
6
|
Airapetov MI, Eresko SO, Lebedev AA, Bychkov ER, Shabanov PD. Expression of the growth hormone secretagogue receptor 1a (GHS-R1a) in the brain. Physiol Rep 2021; 9:e15113. [PMID: 34755494 PMCID: PMC8578894 DOI: 10.14814/phy2.15113] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 10/23/2021] [Accepted: 10/26/2021] [Indexed: 12/17/2022] Open
Abstract
The review presents data on the expression of growth hormone secretagogue receptor 1a (GHS-R1a) in the brain regions in model animals (zebrafish, rodents, primates), and in the human brain. Studies show widespread distribution of the receptor in the brain, which evidences the involvement of the receptor in many physiological processes. Using various organisms, data have been obtained regarding the participation of the GHS-R1a in the regulation of the anti- and pro-inflammatory response, proliferation, and apoptosis. It is known that the receptor plays an important role in eating behavior and is also involved in the pathogenetic mechanisms of drug addiction, obesity, and chronic alcohol consumption. Based on this, research is underway with the use of various therapeutic agents that can be used for the pharmacological correction of these conditions. This review also presents hypothetical pathways of intracellular signaling, in which GHS-R1a may participate. A complete understanding of these mechanisms has not yet been reached. The ghrelin intracellular signaling seem to be specific to brain region and, probably, also depend on the metabolic or stress status of the organism.
Collapse
Affiliation(s)
- Marat I. Airapetov
- Department of NeuropharmacologyInstitute of Experimental MedicineSt. PetersburgRussia
- Department of PharmacologySt. Petersburg State Pediatric Medical UniversitySt. PetersburgRussia
| | - Sergei O. Eresko
- Department of NeuropharmacologyInstitute of Experimental MedicineSt. PetersburgRussia
- Research and Training Center of Molecular and Cellular TechnologiesSt. Petersburg State Chemical Pharmaceutical UniversitySt PetersburgRussia
- Department of BiologySaint‐Petersburg State UniversitySt PetersburgRussia
| | - Andrei A. Lebedev
- Department of NeuropharmacologyInstitute of Experimental MedicineSt. PetersburgRussia
| | - Evgenii R. Bychkov
- Department of NeuropharmacologyInstitute of Experimental MedicineSt. PetersburgRussia
- Department of PharmacologyKirov Military Medical AcademySt. PetersburgRussia
| | - Petr D. Shabanov
- Department of NeuropharmacologyInstitute of Experimental MedicineSt. PetersburgRussia
- Department of PharmacologyKirov Military Medical AcademySt. PetersburgRussia
| |
Collapse
|
7
|
Micioni Di Bonaventura E, Botticelli L, Del Bello F, Giorgioni G, Piergentili A, Quaglia W, Cifani C, Micioni Di Bonaventura MV. Assessing the role of ghrelin and the enzyme ghrelin O-acyltransferase (GOAT) system in food reward, food motivation, and binge eating behavior. Pharmacol Res 2021; 172:105847. [PMID: 34438062 DOI: 10.1016/j.phrs.2021.105847] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/19/2021] [Accepted: 08/20/2021] [Indexed: 02/06/2023]
Abstract
The peripheral peptide hormone ghrelin is a powerful stimulator of food intake, which leads to body weight gain and adiposity in both rodents and humans. The hormone, thus, increases the vulnerability to obesity and binge eating behavior. Several studies have revealed that ghrelin's functions are due to its interaction with the growth hormone secretagogue receptor type 1a (GHSR1a) in the hypothalamic area; besides, ghrelin also promotes the reinforcing properties of hedonic food, acting at extra-hypothalamic sites and interacting with dopaminergic, cannabinoid, opioid, and orexin signaling. The hormone is primarily present in two forms in the plasma and the enzyme ghrelin O-acyltransferase (GOAT) allows the acylation reaction which causes the transformation of des-acyl-ghrelin (DAG) to the active form acyl-ghrelin (AG). DAG has been demonstrated to show antagonist properties; it is metabolically active, and counteracts the effects of AG on glucose metabolism and lipolysis, and reduces food consumption, body weight, and hedonic feeding response. Both peptides seem to influence the hypothalamic-pituitary-adrenal (HPA) axis and the corticosterone/cortisol level that drive the urge to eat under stressful conditions. These findings suggest that DAG and inhibition of GOAT may be targets for obesity and bingeing-related eating disorders and that AG/DAG ratio may be an important potential biomarker to assess the risk of developing maladaptive eating behaviors.
Collapse
Affiliation(s)
| | - Luca Botticelli
- School of Pharmacy, Pharmacology Unit, University of Camerino, via Madonna delle Carceri, 9, 62032 Camerino, Italy
| | - Fabio Del Bello
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, via S. Agostino, 1, 62032 Camerino, Italy
| | - Gianfabio Giorgioni
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, via S. Agostino, 1, 62032 Camerino, Italy
| | - Alessandro Piergentili
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, via S. Agostino, 1, 62032 Camerino, Italy
| | - Wilma Quaglia
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, via S. Agostino, 1, 62032 Camerino, Italy
| | - Carlo Cifani
- School of Pharmacy, Pharmacology Unit, University of Camerino, via Madonna delle Carceri, 9, 62032 Camerino, Italy.
| | | |
Collapse
|
8
|
Airapetov MI, Eresko SO, Lebedev AA, Bychkov ER, Shabanov PD. Expression of Ghrelin Receptor GHS-R1a in the Brain (Mini Review). Mol Biol 2021. [DOI: 10.1134/s002689332103002x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
9
|
Orellana ER, Piscura MK, Horvath N, Hajnal A. Differential Response in Ethanol Behaviors of Female Rats Given Various Weight Loss Surgeries. Alcohol Alcohol 2021; 56:599-604. [PMID: 34343232 DOI: 10.1093/alcalc/agab054] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/12/2021] [Accepted: 07/14/2021] [Indexed: 12/15/2022] Open
Abstract
AIMS Currently, the only effective treatment for morbid obesity and its comorbidities is weight loss surgery (WLS). Growing evidence suggests that different types of WLS, such as Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), have differential effects on alcohol consumption in humans and rats. Thus, we aimed to directly compare the effects of these two surgical procedures, for the first time in female rats, and to determine whether presence or absence of the ghrelin-producing stomach tissue has critical influence on postoperative alcohol intake. METHODS We performed two experiments using an identical behavioral protocol, a continuous-access two-bottle choice protocol for various concentrations of ethanol (EtOH). In Experiment 1, 23 high fat diet (HFD) obese, female rats were randomized to three groups: RYGB, SG or sham-operated food-restricted (Sham) controls. In Experiment 2, HFD obese female rats received either sham (n = 11) or a modified RYGB surgery where the remnant stomach was removed (RYGB-X; n = 12). RESULTS SG rats drank significantly less than RYGB for 4, 6 and 8% and significantly less than Sham for 6, 8 and 8% reinstatement. RYGB-X consumed significantly less EtOH than Sham across all concentrations, reaching significance for 6 and 8% reinstatement. CONCLUSION These findings confirm reduced EtOH consumption by female SG rats as opposed to increased intake following RYGB, and provide the first experimental evidence that the remnant stomach in the RYGB procedure is contributory. Future studies in rats and humans are warranted to confirm that ghrelin plays a critical role in susceptibility to AUD development following WLS.
Collapse
Affiliation(s)
- Elise R Orellana
- Georgetown University, School of Medicine, Department of Biochemistry and Molecular & Cellular Biology, 3900 Reservoir Road NW, Washington, DC, 20009
| | - Mary K Piscura
- The Pennsylvania State University, College of Medicine, Department of Neural and Behavioral Sciences, 700 HMC Crescent road, Hershey, PA 17033
| | - Nelli Horvath
- The Pennsylvania State University, College of Medicine, Department of Neural and Behavioral Sciences, 700 HMC Crescent road, Hershey, PA 17033
| | - Andras Hajnal
- The Pennsylvania State University, College of Medicine, Department of Neural and Behavioral Sciences, 700 HMC Crescent road, Hershey, PA 17033
| |
Collapse
|
10
|
Stoyanova I, Lutz D. Ghrelin-Mediated Regeneration and Plasticity After Nervous System Injury. Front Cell Dev Biol 2021; 9:595914. [PMID: 33869167 PMCID: PMC8046019 DOI: 10.3389/fcell.2021.595914] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 02/24/2021] [Indexed: 12/17/2022] Open
Abstract
The nervous system is highly vulnerable to different factors which may cause injury followed by an acute or chronic neurodegeneration. Injury involves a loss of extracellular matrix integrity, neuronal circuitry disintegration, and impairment of synaptic activity and plasticity. Application of pleiotropic molecules initiating extracellular matrix reorganization and stimulating neuronal plasticity could prevent propagation of the degeneration into the tissue surrounding the injury. To find an omnipotent therapeutic molecule, however, seems to be a fairly ambitious task, given the complex demands of the regenerating nervous system that need to be fulfilled. Among the vast number of candidates examined so far, the neuropeptide and hormone ghrelin holds within a very promising therapeutic potential with its ability to cross the blood-brain barrier, to balance metabolic processes, and to stimulate neurorepair and neuroactivity. Compared with its well-established systemic effects in treatment of metabolism-related disorders, the therapeutic potential of ghrelin on neuroregeneration upon injury has received lesser appreciation though. Here, we discuss emerging concepts of ghrelin as an omnipotent player unleashing developmentally related molecular cues and morphogenic cascades, which could attenuate and/or counteract acute and chronic neurodegeneration.
Collapse
Affiliation(s)
- Irina Stoyanova
- Department of Anatomy and Cell Biology, Medical University Varna, Varna, Bulgaria
| | - David Lutz
- Department of Neuroanatomy and Molecular Brain Research, Ruhr University Bochum, Bochum, Germany
| |
Collapse
|
11
|
Cornejo MP, Mustafá ER, Barrile F, Cassano D, De Francesco PN, Raingo J, Perello M. THE INTRIGUING LIGAND-DEPENDENT AND LIGAND-INDEPENDENT ACTIONS OF THE GROWTH HORMONE SECRETAGOGUE RECEPTOR ON REWARD-RELATED BEHAVIORS. Neurosci Biobehav Rev 2020; 120:401-416. [PMID: 33157147 DOI: 10.1016/j.neubiorev.2020.10.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/18/2020] [Accepted: 10/20/2020] [Indexed: 02/07/2023]
Abstract
The growth hormone secretagogue receptor (GHSR) is a G-protein-coupled receptor (GPCR) highly expressed in the brain, and also in some peripheral tissues. GHSR activity is evoked by the stomach-derived peptide hormone ghrelin and abrogated by the intestine-derived liver-expressed antimicrobial peptide 2 (LEAP2). In vitro, GHSR displays ligand-independent actions, including a high constitutive activity and an allosteric modulation of other GPCRs. Beyond its neuroendocrine and metabolic effects, cumulative evidence shows that GHSR regulates the activity of the mesocorticolimbic pathway and modulates complex reward-related behaviors towards different stimuli. Here, we review current evidence indicating that ligand-dependent and ligand-independent actions of GHSR enhance reward-related behaviors towards appetitive stimuli and drugs of abuse. We discuss putative neuronal networks and molecular mechanisms that GHSR would engage to modulate such reward-related behaviors. Finally, we briefly discuss imaging studies showing that ghrelin would also regulate reward processing in humans. Overall, we conclude that GHSR is a key regulator of the mesocorticolimbic pathway that influences its activity and, consequently, modulates reward-related behaviors via ligand-dependent and ligand-independent actions.
Collapse
Affiliation(s)
- María P Cornejo
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Emilio R Mustafá
- Laboratory of Electrophysiology of the IMBICE, 1900 La Plata, Buenos Aires, Argentina
| | - Franco Barrile
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Daniela Cassano
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Pablo N De Francesco
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina
| | - Jesica Raingo
- Laboratory of Electrophysiology of the IMBICE, 1900 La Plata, Buenos Aires, Argentina
| | - Mario Perello
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology [IMBICE, Argentine Research Council (CONICET) and Scientific Research Commission, Province of Buenos Aires (CIC-PBA). National University of La Plata], 1900 La Plata, Buenos Aires, Argentina.
| |
Collapse
|
12
|
Islam MN, Mita Y, Maruyama K, Tanida R, Zhang W, Sakoda H, Nakazato M. Liver-expressed antimicrobial peptide 2 antagonizes the effect of ghrelin in rodents. J Endocrinol 2020; 244:13-23. [PMID: 31539874 PMCID: PMC6839046 DOI: 10.1530/joe-19-0102] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 09/19/2019] [Indexed: 12/21/2022]
Abstract
Ghrelin, a stomach-derived peptide, promotes feeding and growth hormone (GH) secretion. A recent study identified liver-expressed antimicrobial peptide 2 (LEAP2) as an endogenous inhibitor of ghrelin-induced GH secretion, but the effect of LEAP2 in the brain remained unknown. In this study, we showed that intracerebroventricular (i.c.v.) administration of LEAP2 to rats suppressed central ghrelin functions including Fos expression in the hypothalamic nuclei, promotion of food intake, blood glucose elevation, and body temperature reduction. LEAP2 did not inhibit neuropeptide Y (NPY)-induced food intake or des-acyl ghrelin-induced reduction in body temperature, indicating that the inhibitory effects of LEAP2 were specific for GHSR. Plasma LEAP2 levels varied according to feeding status and seemed to be dependent on the hepatic Leap2 expression. Furthermore, ghrelin suppressed the expression of hepatic Leap2 via AMPK activation. Together, these results reveal that LEAP2 inhibits central ghrelin functions and crosstalk between liver and stomach.
Collapse
Affiliation(s)
- Md Nurul Islam
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Yuichiro Mita
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- Systems Life Sciences Laboratory, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, Japan
| | - Keisuke Maruyama
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Ryota Tanida
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- Department of Sports and Fitness, Faculty of Wellness, Shigakkan University, Aichi, Japan
| | - Weidong Zhang
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Hideyuki Sakoda
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Masamitsu Nakazato
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- CREST (Japan) Agency for Medical Research and Development (A-MED) 1-7-1 Otemachi, Tokyo, Japan
- Correspondence should be addressed to M Nakazato:
| |
Collapse
|
13
|
Ratcliff M, Rees D, McGrady S, Buntwal L, Hornsby AKE, Bayliss J, Kent BA, Bussey T, Saksida L, Beynon AL, Howell OW, Morgan AH, Sun Y, Andrews ZB, Wells T, Davies JS. Calorie restriction activates new adult born olfactory-bulb neurones in a ghrelin-dependent manner but acyl-ghrelin does not enhance subventricular zone neurogenesis. J Neuroendocrinol 2019; 31:e12755. [PMID: 31179562 DOI: 10.1111/jne.12755] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 06/06/2019] [Accepted: 06/06/2019] [Indexed: 12/25/2022]
Abstract
The ageing and degenerating brain show deficits in neural stem/progenitor cell (NSPC) plasticity that are accompanied by impairments in olfactory discrimination. Emerging evidence suggests that the gut hormone ghrelin plays an important role in protecting neurones, promoting synaptic plasticity and increasing hippocampal neurogenesis in the adult brain. In the present study, we investigated the role of ghrelin with respect to modulating adult subventricular zone (SVZ) NSPCs that give rise to new olfactory bulb (OB) neurones. We characterised the expression of the ghrelin receptor, growth hormone secretagogue receptor (GHSR), using an immunohistochemical approach in GHSR-eGFP reporter mice to show that GHSR is expressed in several regions, including the OB but not in the SVZ of the lateral ventricle. These data suggest that acyl-ghrelin does not mediate a direct effect on NSPC in the SVZ. Consistent with these findings, treatment with acyl-ghrelin or genetic silencing of GHSR did not alter NSPC proliferation within the SVZ. Similarly, using a bromodeoxyuridine pulse-chase approach, we show that peripheral treatment of adult rats with acyl-ghrelin did not increase the number of new adult-born neurones in the granule cell layer of the OB. These data demonstrate that acyl-ghrelin does not increase adult OB neurogenesis. Finally, we investigated whether elevating ghrelin indirectly, via calorie restriction (CR), regulated the activity of new adult-born cells in the OB. Overnight CR induced c-Fos expression in new adult-born OB cells but not in developmentally born cells, whereas neuronal activity was absent following re-feeding. These effects were not present in ghrelin-/- mice, suggesting that adult-born cells are uniquely sensitive to changes in ghrelin mediated by fasting and re-feeding. In summary, ghrelin does not promote neurogenesis in the SVZ and OB; however, new adult-born OB cells are activated by CR in a ghrelin-dependent manner.
Collapse
Affiliation(s)
- Michael Ratcliff
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Daniel Rees
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Scott McGrady
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Luke Buntwal
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Amanda K E Hornsby
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Jaqueline Bayliss
- Biomedical Discovery Unit, Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Brianne A Kent
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | | | | | - Amy L Beynon
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Owain W Howell
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Alwena H Morgan
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| | - Yuxiang Sun
- Department of Nutrition and Food Science, Texas A&M University, College Station, Texas, USA
| | - Zane B Andrews
- Biomedical Discovery Unit, Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Timothy Wells
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Jeffrey S Davies
- Molecular Neurobiology, Institute of Life Sciences, School of Medicine, Swansea University, Swansea, UK
| |
Collapse
|
14
|
Abizaid A. Stress and obesity: The ghrelin connection. J Neuroendocrinol 2019; 31:e12693. [PMID: 30714236 DOI: 10.1111/jne.12693] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 01/01/2019] [Accepted: 01/29/2019] [Indexed: 12/20/2022]
Abstract
Ghrelin is a hormone associated with feeding and energy balance. Not surprisingly, this hormone is secreted in response to acute stressors and it is chronically elevated after exposure to chronic stress in tandem with a number of metabolic changes aimed at attaining homeostatic balance. In the present review, we propose that ghrelin plays a key role in these stress-induced homeostatic processes. Ghrelin targets the hypothalamus and brain stem nuclei that are part of the sympathetic nervous system to increase appetite and energy expenditure and promote the use of carbohydrates as a source of fuel at the same time as sparing fat. Ghrelin also targets mesolimbic brain regions such as the ventral segmental area and the hippocampus to modulate reward processes, to protect against damage associated with chronic stress, as well as to potentially increase resilience to stress. In all, these data support the notion that ghrelin, similar to corticosterone, is a critical metabolic hormone that is essential for the stress response.
Collapse
Affiliation(s)
- Alfonso Abizaid
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| |
Collapse
|
15
|
Mani BK, Shankar K, Zigman JM. Ghrelin's Relationship to Blood Glucose. Endocrinology 2019; 160:1247-1261. [PMID: 30874792 PMCID: PMC6482034 DOI: 10.1210/en.2019-00074] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 03/09/2019] [Indexed: 12/16/2022]
Abstract
Much effort has been directed at studying the orexigenic actions of administered ghrelin and the potential effects of the endogenous ghrelin system on food intake, food reward, body weight, adiposity, and energy expenditure. Although endogenous ghrelin's actions on some of these processes remain ambiguous, its glucoregulatory actions have emerged as well-recognized features during extreme metabolic conditions. The blood glucose-raising actions of ghrelin are beneficial during starvation-like conditions, defending against life-threatening falls in blood glucose, but they are seemingly detrimental in obese states and in certain monogenic forms of diabetes, contributing to hyperglycemia. Also of interest, blood glucose negatively regulates ghrelin secretion. This article reviews the literature suggesting the existence of a blood glucose-ghrelin axis and highlights the factors that mediate the glucoregulatory actions of ghrelin, especially during metabolic extremes such as starvation and diabetes.
Collapse
Affiliation(s)
- Bharath K Mani
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Kripa Shankar
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jeffrey M Zigman
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas
- Correspondence: Jeffrey M. Zigman, MD, PhD, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390. E-mail:
| |
Collapse
|
16
|
Dos-Santos RC, Reis LC, Perello M, Ferguson AV, Mecawi AS. The actions of ghrelin in the paraventricular nucleus: energy balance and neuroendocrine implications. Ann N Y Acad Sci 2019; 1455:81-97. [PMID: 31008525 DOI: 10.1111/nyas.14087] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 02/28/2019] [Accepted: 03/10/2019] [Indexed: 12/15/2022]
Abstract
Ghrelin is a peptide mainly produced and secreted by the stomach. Since its discovery, the impact of ghrelin on the regulation of food intake has been the most studied function of this hormone; however, ghrelin affects a wide range of physiological systems, many of which are controlled by the hypothalamic paraventricular nucleus (PVN). Several pathways may mediate the effects of ghrelin on PVN neurons, such as direct or indirect effects mediated by circumventricular organs and/or the arcuate nucleus. The ghrelin receptor is expressed in PVN neurons, and the peripheral or intracerebroventricular administration of ghrelin affects PVN neuronal activity. Intra-PVN application of ghrelin increases food intake and decreases fat oxidation, which chronically contribute to the increased adiposity. Additionally, ghrelin modulates the neuroendocrine axes controlled by the PVN, increasing the release of vasopressin and oxytocin by magnocellular neurons and corticotropin-releasing hormone by neuroendocrine parvocellular neurons, while possibly inhibiting the release of thyrotropin-releasing hormone. Thus, the PVN is an important target for the actions of ghrelin. Our review discusses the mechanisms of ghrelin actions in the PVN, and its potential implications for energy balance, neuroendocrine, and integrative physiological control.
Collapse
Affiliation(s)
- Raoni C Dos-Santos
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Luís C Reis
- Department of Physiological Sciences, Federal Rural University of Rio de Janeiro, Seropédica, Brazil
| | - Mario Perello
- Laboratory of Neurophysiology, Multidisciplinary Institute of Cell Biology, La Plata, Argentina
| | - Alastair V Ferguson
- Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
| | - André S Mecawi
- Laboratory of Neuroendocrinology, Department of Biophysics, Paulista Medical School, Federal University of São Paulo, São Paulo, Brazil
| |
Collapse
|
17
|
Kirsch M. On the Abilities of Unconscious Freudian Motivational Drives to Evoke Conscious Emotions. Front Psychol 2019; 10:470. [PMID: 30899234 PMCID: PMC6416170 DOI: 10.3389/fpsyg.2019.00470] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 02/18/2019] [Indexed: 12/27/2022] Open
Abstract
Human beings use conscious emotions to direct their behaviors. There is some agreement in the scientific community that unconscious motivations are able to evoke conscious emotions. This manuscript focuses on Freudian motivational drives as inductors for unconscious motivation, and also on Panksepp's framework of affective neuroscience for describing the generation of emotions. Recently, it has been suggested that imperative motor factors of Freudian drives (i.e., the hormones ghrelin, testosterone, angiotensin II and adenosine) have the ability to activate both a drive-specific brain area and brain areas of the SEEKING command system. In fact, this manuscript contends that all imperative motor factors have typical SEEKING targets (i.e., so-called receptors) in the brain areas of both nucleus accumbens and lateral hypothalamus. In addition, all imperative motor factors are able to target the central amygdala directly, a brain area classified by Panksepp as the instinctual part of the FEAR command system. Another point of interest may be the evaluation that imperative motor factors of the sexual drive, hunger and thirst can directly activate the RAGE command system by targeting the medial amygdala. Surprisingly, all imperative motor factors are able to modulate Panksepp's granddaddy mechanism, i.e., to stimulate all seven command systems via the lateral hypothalamus. Orexinergic neurons exclusively located in the lateral hypothalamus have targets for imperative motor factors and project axons to characteristic brain areas of all seven command systems. From the fact that the imperative motor factors of the sexual drive and hunger act in an excitatory manner on orexinergic neurons whereas those of thirst and sleep inhibit such neurons, temporary termination of hunger by thirst may be understood as a very simple example of a co-regulation of Freudian drives. The author wishes to note that there are motivational drives other than the ones described by Freud. Bowlby was obviously the first in describing such drives, and Bowlbyian drive activities cannot be explained with the intermediacy of imperative motor factors. Nevertheless, the ignorance of the magnificent importance of imperative motor factors must be discarded.
Collapse
Affiliation(s)
- Michael Kirsch
- Institute of Physiological Chemistry, Essen University Hospital, Essen, Germany
| |
Collapse
|
18
|
Morris LS, Voon V, Leggio L. Stress, Motivation, and the Gut-Brain Axis: A Focus on the Ghrelin System and Alcohol Use Disorder. Alcohol Clin Exp Res 2018; 42:10.1111/acer.13781. [PMID: 29797564 PMCID: PMC6252147 DOI: 10.1111/acer.13781] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 05/17/2018] [Indexed: 01/04/2023]
Abstract
Since its discovery, the gut hormone, ghrelin, has been implicated in diverse functional roles in the central nervous system. Central and peripheral interactions between ghrelin and other hormones, including the stress-response hormone cortisol, govern complex behavioral responses to external cues and internal states. By acting at ventral tegmental area dopaminergic projections and other areas involved in reward processing, ghrelin can induce both general and directed motivation for rewards, including craving for alcohol and other alcohol-seeking behaviors. Stress-induced increases in cortisol seem to increase ghrelin in the periphery, suggesting a pathway by which ghrelin influences how stressful life events trigger motivation for rewards. However, in some states, ghrelin may be protective against the anxiogenic effects of stressors. This critical review brings together a dynamic and growing literature, that is, at times inconsistent, on the relationships between ghrelin, central reward-motivation pathways, and central and peripheral stress responses, with a special focus on its emerging role in the context of alcohol use disorder.
Collapse
Affiliation(s)
- Laurel S. Morris
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, UK
- Department of Psychology, University of Cambridge, UK
- Mood and Anxiety Disorders Program, Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Valerie Voon
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, UK
- Department of Psychiatry, University of Cambridge, UK
| | - Lorenzo Leggio
- Section on Clinical Psychoneuroendocrinology and Neuropsychopharmacology, National Institute on Alcohol Abuse and Alcoholism and National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, USA
- Center for Alcohol and Addiction Studies, Department of Behavioral and Social Sciences, Brown University, Providence, RI, USA
| |
Collapse
|
19
|
So M, Hashimoto H, Saito R, Yamamoto Y, Motojima Y, Ueno H, Sonoda S, Yoshimura M, Maruyama T, Kusuhara K, Ueta Y. Inhibition of ghrelin-induced feeding in rats by pretreatment with a novel dual orexin receptor antagonist. J Physiol Sci 2018; 68:129-136. [PMID: 28054308 PMCID: PMC6394659 DOI: 10.1007/s12576-016-0517-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 12/22/2016] [Indexed: 12/14/2022]
Abstract
Orexin-A and -B, and ghrelin are potent orexigenic peptides. The effects of ACT462206, a novel dual orexin receptor antagonist (DORA), on ghrelin-induced feeding were examined in adult male Wistar rats. Hyperphagia induced by the intracerebroventricular (icv) administration of ghrelin was significantly suppressed for at least 2 h by pretreatment with icv administration of DORA. A marked increase was observed in the number of neurons showing Fos immunoreactivity in the paraventricular nucleus, arcuate nucleus and lateral hypothalamic area (LHA), 90 min after icv administration of ghrelin. Pretreatment with DORA significantly decreased the number of Fos-immunoreactive (IR) neurons; however, Fos immunoreactivity remained significantly increased. Double-immunostaining for Fos and orexin-A showed that many orexin-A-IR neurons in the LHA coexisted with Fos immunoreactivity after icv administration of ghrelin, but their number was reduced significantly by DORA pretreatment. These results suggest that centrally administered ghrelin may activate the orexinergic and non-orexinergic pathways responsible for the regulation of feeding.
Collapse
Affiliation(s)
- Mariko So
- Department of Health and Nutritional Care, Faculty of Medical Science, University of East Asia, Shimonoseki, 751-0807, Japan
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, 807-8555, Japan
| | - Hirofumi Hashimoto
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, 807-8555, Japan
| | - Reiko Saito
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, 807-8555, Japan
- Department of Pediatrics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555, Japan
| | - Yukiyo Yamamoto
- Department of Pediatrics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555, Japan
| | - Yasuhito Motojima
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, 807-8555, Japan
| | - Hiromichi Ueno
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, 807-8555, Japan
| | - Satomi Sonoda
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, 807-8555, Japan
| | - Mitsuhiro Yoshimura
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, 807-8555, Japan
| | - Takashi Maruyama
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, 807-8555, Japan
| | - Koichi Kusuhara
- Department of Pediatrics, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555, Japan
| | - Yoichi Ueta
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu, 807-8555, Japan.
| |
Collapse
|
20
|
Camargo-Silva G, Turones LC, da Cruz KR, Gomes KP, Mendonça MM, Nunes A, de Jesus IG, Colugnati DB, Pansani AP, Pobbe RLH, Santos R, Fontes MAP, Guatimosim S, de Castro CH, Ianzer D, Ferreira RN, Xavier CH. Ghrelin potentiates cardiac reactivity to stress by modulating sympathetic control and beta-adrenergic response. Life Sci 2018; 196:84-92. [PMID: 29366747 DOI: 10.1016/j.lfs.2018.01.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 01/10/2018] [Accepted: 01/18/2018] [Indexed: 02/07/2023]
Abstract
Prior evidence indicates that ghrelin is involved in the integration of cardiovascular functions and behavioral responses. Ghrelin actions are mediated by the growth hormone secretagogue receptor subtype 1a (GHS-R1a), which is expressed in peripheral tissues and central areas involved in the control of cardiovascular responses to stress. AIMS In the present study, we assessed the role of ghrelin - GHS-R1a axis in the cardiovascular reactivity to acute emotional stress in rats. MAIN METHODS AND KEY FINDINGS Ghrelin potentiated the tachycardia evoked by restraint and air jet stresses, which was reverted by GHS-R1a blockade. Evaluation of the autonomic balance revealed that the sympathetic branch modulates the ghrelin-evoked positive chronotropy. In isolated hearts, the perfusion with ghrelin potentiated the contractile responses caused by stimulation of the beta-adrenergic receptor, without altering the amplitude of the responses evoked by acetylcholine. Experiments in isolated cardiomyocytes revealed that ghrelin amplified the increases in calcium transient changes evoked by isoproterenol. SIGNIFICANCE Taken together, our results indicate that the Ghrelin-GHS-R1a axis potentiates the magnitude of stress-evoked tachycardia by modulating the autonomic nervous system and peripheral mechanisms, strongly relying on the activation of cardiac calcium transient and beta-adrenergic receptors.
Collapse
Affiliation(s)
- Gabriel Camargo-Silva
- Laboratory of Cardiovascular Physiology and Therapeutics, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil
| | - Larissa Córdova Turones
- Laboratory of Cardiovascular Physiology and Therapeutics, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil
| | - Kellen Rosa da Cruz
- Laboratory of Cardiovascular Physiology and Therapeutics, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil
| | - Karina Pereira Gomes
- Integrative Laboratory of Cardiovascular and Neurological Pathophysiology, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil
| | - Michelle Mendanha Mendonça
- Laboratory of Cardiovascular Physiology and Therapeutics, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil
| | - Allancer Nunes
- Integrative Laboratory of Cardiovascular and Neurological Pathophysiology, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil
| | - Itamar Guedes de Jesus
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Diego Basile Colugnati
- Integrative Laboratory of Cardiovascular and Neurological Pathophysiology, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil
| | - Aline Priscila Pansani
- Integrative Laboratory of Cardiovascular and Neurological Pathophysiology, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil
| | - Roger Luis Henschel Pobbe
- Laboratory of Cardiovascular Physiology and Therapeutics, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil
| | - Robson Santos
- National Institute of Science and Technology Nanobiopharmaceutics (INCT NanoBioFar), Brazil
| | | | - Silvia Guatimosim
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil; National Institute of Science and Technology Nanobiopharmaceutics (INCT NanoBioFar), Brazil
| | - Carlos Henrique de Castro
- Integrative Laboratory of Cardiovascular and Neurological Pathophysiology, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil; National Institute of Science and Technology Nanobiopharmaceutics (INCT NanoBioFar), Brazil
| | - Danielle Ianzer
- Laboratory of Cardiovascular Physiology and Therapeutics, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil; National Institute of Science and Technology Nanobiopharmaceutics (INCT NanoBioFar), Brazil
| | - Reginaldo Nassar Ferreira
- Laboratory of Cardiovascular Physiology and Therapeutics, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil
| | - Carlos Henrique Xavier
- Laboratory of Cardiovascular Physiology and Therapeutics, Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiania, GO, Brazil; National Institute of Science and Technology Nanobiopharmaceutics (INCT NanoBioFar), Brazil.
| |
Collapse
|
21
|
Ubaldo-Reyes L, Buijs R, Escobar C, Ángeles-Castellanos M. Scheduled meal accelerates entrainment to a 6-h phase advance by shifting central and peripheral oscillations in rats. Eur J Neurosci 2017; 46:1875-1886. [DOI: 10.1111/ejn.13633] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 04/24/2017] [Accepted: 06/20/2017] [Indexed: 12/11/2022]
Affiliation(s)
- L.M. Ubaldo-Reyes
- Departamento de Anatomía; Facultad de Medicina; Universidad Nacional Autónoma de México; México DF 04510 Mexico
| | - R.M. Buijs
- Laboratorio Mecanismos de Integración Hipotalámica; Instituto de Investigaciones Biomédicas; Universidad Nacional Autónoma de México; México DF Mexico
| | - C. Escobar
- Departamento de Anatomía; Facultad de Medicina; Universidad Nacional Autónoma de México; México DF 04510 Mexico
| | - M. Ángeles-Castellanos
- Departamento de Anatomía; Facultad de Medicina; Universidad Nacional Autónoma de México; México DF 04510 Mexico
| |
Collapse
|
22
|
Ge T, Yang W, Fan J, Li B. Preclinical evidence of ghrelin as a therapeutic target in epilepsy. Oncotarget 2017; 8:59929-59939. [PMID: 28938694 PMCID: PMC5601790 DOI: 10.18632/oncotarget.18349] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 05/22/2017] [Indexed: 12/17/2022] Open
Abstract
Ghrelin, an orexigenic peptide synthesized by endocrine cells of the gastric mucosa, plays a major role in inhibiting seizures. However, the underlying mechanism of ghrelin's anticonvulsant action is still unclear. Nowadays, there are considerable evidences showing that ghrelin is implicated in various neurophysiological processes, including learning and memory, neuroprotection, neurogenesis, and inflammatory effects. In this review, we will summarize the effects of ghrelin on epilepsy. It may provide a comprehensive picture of the role of ghrelin in epilepsy.
Collapse
Affiliation(s)
- Tongtong Ge
- Jilin Provincial Key Laboratory on Molecular and Chemical Genetics, The Second Hospital of Jilin University, Changchun 130041, PR China
| | - Wei Yang
- Jilin Provincial Key Laboratory on Molecular and Chemical Genetics, The Second Hospital of Jilin University, Changchun 130041, PR China
| | - Jie Fan
- Jilin Provincial Key Laboratory on Molecular and Chemical Genetics, The Second Hospital of Jilin University, Changchun 130041, PR China
| | - Bingjin Li
- Jilin Provincial Key Laboratory on Molecular and Chemical Genetics, The Second Hospital of Jilin University, Changchun 130041, PR China
| |
Collapse
|
23
|
Anderson LL, Jeftinija S, Scanes CG. Growth Hormone Secretion: Molecular and Cellular Mechanisms and In Vivo Approaches. Exp Biol Med (Maywood) 2016; 229:291-302. [PMID: 15044712 DOI: 10.1177/153537020422900403] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Growth hormone (GH) release is under the direct control of hypothalamic releasing hormones, some being also produced peripherally. The role of these hypothalamic factors has been understood by in vitro studies together with such in vivo approaches as stalk sectioning. Secretion of GH is stimulated by GH-releasing hormone (GHRH) and ghrelin (acting via the GH secretagogue [GHS] receptor [GHSR]), and inhibited by somatostatin (SRIF). Other peptides/proteins influence GH secretion, at least in some species. The cellular mechanism by which the releasing hormones affect GH secretion from the somatotrope requires specific signal transduction systems (cAMP and/or calcium influx and/or mobilization of intracellular calcium) and/or tyrosine kinase(s) and/or nitric oxide (NO)/cGMP. At the subcellular level, GH release (at least in response to GHS) is accomplished by the following. The GH-containing secretory granules are moved close to the cell surface. There is then transient fusion of the secretory granules with the fusion pores in the multiple secretory pits in the somatotrope cell surface.
Collapse
Affiliation(s)
- Lloyd L Anderson
- Department of Animal Science, Iowa State University, Ames, Iowa 50011, USA.
| | | | | |
Collapse
|
24
|
Edwards A, Abizaid A. Driving the need to feed: Insight into the collaborative interaction between ghrelin and endocannabinoid systems in modulating brain reward systems. Neurosci Biobehav Rev 2016; 66:33-53. [PMID: 27136126 DOI: 10.1016/j.neubiorev.2016.03.032] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 03/08/2016] [Accepted: 03/31/2016] [Indexed: 01/29/2023]
Abstract
Independent stimulation of either the ghrelin or endocannabinoid system promotes food intake and increases adiposity. Given the similar distribution of their receptors in feeding associated brain regions and organs involved in metabolism, it is not surprising that evidence of their interaction and its importance in modulating energy balance has emerged. This review documents the relationship between ghrelin and endocannabinoid systems within the periphery and hypothalamus (HYP) before presenting evidence suggesting that these two systems likewise work collaboratively within the ventral tegmental area (VTA) to modulate non-homeostatic feeding. Mechanisms, consistent with current evidence and local infrastructure within the VTA, will be proposed.
Collapse
Affiliation(s)
- Alexander Edwards
- Department of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
| | - Alfonso Abizaid
- Department of Neuroscience, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
| |
Collapse
|
25
|
Growth Hormone Secretagogue Receptor Dimers: A New Pharmacological Target. eNeuro 2015; 2:eN-REV-0053-14. [PMID: 26464979 PMCID: PMC4596092 DOI: 10.1523/eneuro.0053-14.2015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/25/2015] [Accepted: 04/07/2015] [Indexed: 01/04/2023] Open
Abstract
The growth hormone secretagogue receptor (GHSR1a), the target of the ghrelin peptide, is widely distributed throughout the brain, and, while studies have often reported very low or absent levels of central ghrelin, it is now known that GHSR1a, even in the absence of a natural ligand, has physiological roles. Not only do these roles originate from the receptor's constitutive activity, but recent data indicate that GHSR1a dimerizes with a wide array of other receptors. These include the dopamine 1 receptor (D1R), the dopamine 2 receptor (D2R), the melanocortin-3 receptor (MC3R), the serotonin 2C receptor (5-HT2C), and possibly the cannabinoid type 1 receptor (CB1). Within these dimers, signaling of the protomers involved are modified through facilitation, inhibition, and even modification of signaling pathways resulting in physiological consequences not seen in the absence of these dimers. While in some cases the ghrelin peptide is not required for these modifications to occur, in others, the presence is necessary for these changes to take effect. These heterodimers demonstrate the broad array of roles and complexity of the ghrelin system. By better understanding how these dimers work, it is hoped that improved treatments for a variety of disorders, including Parkinson's disease, schizophrenia, addiction, obesity, diabetes, and more, can be devised. In this review, we examine the current state of knowledge surrounding GHSR heterodimers, and how we can apply this knowledge to various pharmacological treatments.
Collapse
|
26
|
Gali Ramamoorthy T, Begum G, Harno E, White A. Developmental programming of hypothalamic neuronal circuits: impact on energy balance control. Front Neurosci 2015; 9:126. [PMID: 25954145 PMCID: PMC4404811 DOI: 10.3389/fnins.2015.00126] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 03/26/2015] [Indexed: 01/08/2023] Open
Abstract
The prevalence of obesity in adults and children has increased globally at an alarming rate. Mounting evidence from both epidemiological studies and animal models indicates that adult obesity and associated metabolic disorders can be programmed by intrauterine and early postnatal environment- a phenomenon known as "fetal programming of adult disease." Data from nutritional intervention studies in animals including maternal under- and over-nutrition support the developmental origins of obesity and metabolic syndrome. The hypothalamic neuronal circuits located in the arcuate nucleus controlling appetite and energy expenditure are set early in life and are perturbed by maternal nutritional insults. In this review, we focus on the effects of maternal nutrition in programming permanent changes in these hypothalamic circuits, with experimental evidence from animal models of maternal under- and over-nutrition. We discuss the epigenetic modifications which regulate hypothalamic gene expression as potential molecular mechanisms linking maternal diet during pregnancy to the offspring's risk of obesity at a later age. Understanding these mechanisms in key metabolic genes may provide insights into the development of preventative intervention strategies.
Collapse
Affiliation(s)
| | - Ghazala Begum
- School of Clinical and Experimental Medicine, University of Birmingham Birmingham, UK
| | - Erika Harno
- Faculty of Life Sciences, University of Manchester Manchester, UK
| | - Anne White
- Faculty of Life Sciences, University of Manchester Manchester, UK ; Faculty of Medical and Human Sciences, Centre for Endocrinology and Diabetes, University of Manchester Manchester, UK
| |
Collapse
|
27
|
Bouret S, Levin BE, Ozanne SE. Gene-environment interactions controlling energy and glucose homeostasis and the developmental origins of obesity. Physiol Rev 2015; 95:47-82. [PMID: 25540138 PMCID: PMC4281588 DOI: 10.1152/physrev.00007.2014] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Obesity and type 2 diabetes mellitus (T2DM) often occur together and affect a growing number of individuals in both the developed and developing worlds. Both are associated with a number of other serious illnesses that lead to increased rates of mortality. There is likely a polygenic mode of inheritance underlying both disorders, but it has become increasingly clear that the pre- and postnatal environments play critical roles in pushing predisposed individuals over the edge into a disease state. This review focuses on the many genetic and environmental variables that interact to cause predisposed individuals to become obese and diabetic. The brain and its interactions with the external and internal environment are a major focus given the prominent role these interactions play in the regulation of energy and glucose homeostasis in health and disease.
Collapse
Affiliation(s)
- Sebastien Bouret
- The Saban Research Institute, Neuroscience Program, Childrens Hospital Los Angeles, University of Southern California, Los Angeles, California; Inserm U837, Jean-Pierre Aubert Research Center, University Lille 2, Lille, France; Neurology Service, Veterans Administration Medical Center, East Orange, New Jersey; Department of Neurology and Neurosciences, Rutgers, New Jersey Medical School, Newark, New Jersey; and University of Cambridge Institute of Metabolic Science and MRC Metabolic Diseases Unit, Cambridge, United Kingdom
| | - Barry E Levin
- The Saban Research Institute, Neuroscience Program, Childrens Hospital Los Angeles, University of Southern California, Los Angeles, California; Inserm U837, Jean-Pierre Aubert Research Center, University Lille 2, Lille, France; Neurology Service, Veterans Administration Medical Center, East Orange, New Jersey; Department of Neurology and Neurosciences, Rutgers, New Jersey Medical School, Newark, New Jersey; and University of Cambridge Institute of Metabolic Science and MRC Metabolic Diseases Unit, Cambridge, United Kingdom
| | - Susan E Ozanne
- The Saban Research Institute, Neuroscience Program, Childrens Hospital Los Angeles, University of Southern California, Los Angeles, California; Inserm U837, Jean-Pierre Aubert Research Center, University Lille 2, Lille, France; Neurology Service, Veterans Administration Medical Center, East Orange, New Jersey; Department of Neurology and Neurosciences, Rutgers, New Jersey Medical School, Newark, New Jersey; and University of Cambridge Institute of Metabolic Science and MRC Metabolic Diseases Unit, Cambridge, United Kingdom
| |
Collapse
|
28
|
Mani BK, Walker AK, Lopez Soto EJ, Raingo J, Lee CE, Perelló M, Andrews ZB, Zigman JM. Neuroanatomical characterization of a growth hormone secretagogue receptor-green fluorescent protein reporter mouse. J Comp Neurol 2014; 522:3644-66. [PMID: 24825838 DOI: 10.1002/cne.23627] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 05/08/2014] [Accepted: 05/09/2014] [Indexed: 12/15/2022]
Abstract
Growth hormone secretagogue receptor (GHSR) 1a is the only molecularly identified receptor for ghrelin, mediating ghrelin-related effects on eating, body weight, and blood glucose control, among others. The expression pattern of GHSR within the brain has been assessed previously by several neuroanatomical techniques. However, inherent limitations to these techniques and the lack of reliable anti-GHSR antibodies and reporter rodent models that identify GHSR-containing neurons have prevented a more comprehensive functional characterization of ghrelin-responsive neurons. Here we have systematically characterized the brain expression of an enhanced green fluorescence protein (eGFP) transgene controlled by the Ghsr promoter in a recently reported GHSR reporter mouse. Expression of eGFP in coronal brain sections was compared with GHSR mRNA expression detected in the same sections by in situ hybridization histochemistry. eGFP immunoreactivity was detected in several areas, including the prefrontal cortex, insular cortex, olfactory bulb, amygdala, and hippocampus, which showed no or low GHSR mRNA expression. In contrast, eGFP expression was low in several midbrain regions and in several hypothalamic nuclei, particularly the arcuate nucleus, where robust GHSR mRNA expression has been well-characterized. eGFP expression in several brainstem nuclei showed high to moderate degrees of colocalization with GHSR mRNA labeling. Further quantitative PCR and electrophysiological analyses of eGFP-labeled hippocampal cells confirmed faithful expression of eGFP within GHSR-containing, ghrelin-responsive neurons. In summary, the GHSR-eGFP reporter mouse model may be a useful tool for studying GHSR function, particularly within the brainstem and hippocampus; however, it underrepresents GHSR expression in nuclei within the hypothalamus and midbrain.
Collapse
Affiliation(s)
- Bharath K Mani
- Division of Hypothalamic Research and Division of Endocrinology and Metabolism, Department of Internal Medicine and Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, 75390-9077
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Abstract
After the discovery in 1996 of the GH secretagogue-receptor type-1a (GHS-R1a) as an orphan G-protein coupled receptor, many research groups attempted to identify the endogenous ligand. Finally, Kojima and colleagues successfully isolated the peptide ligand from rat stomach extracts, determined its structure, and named it ghrelin. The GHS-R1a is now accepted to be the ghrelin receptor. The existence of the ghrelin system has been demonstrated in many animal classes through biochemical and molecular biological strategies as well as through genome projects. Our work, focused on identifying the ghrelin receptor and its ligand ghrelin in laboratory animals, particularly nonmammalian vertebrates, has provided new insights into the molecular evolution of the ghrelin receptor. In mammals, it is assumed that the ghrelin receptor evolution is in line with the plate tectonics theory. In contrast, the evolution of the ghrelin receptor in nonmammalian vertebrates differs from that of mammals: multiplicity of the ghrelin receptor isoforms is observed in nonmammalian vertebrates only. This multiplicity is due to genome duplication and polyploidization events that particularly occurred in Teleostei. Furthermore, it is likely that the evolution of the ghrelin receptor is distinct from that of its ligand, ghrelin, because only one ghrelin isoform has been detected in all species examined so far. In this review, we summarize current knowledge related to the molecular evolution of the ghrelin receptor in mammalian and nonmammalian vertebrates.
Collapse
Affiliation(s)
- Hiroyuki Kaiya
- Department of BiochemistryNational Cerebral and Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan
| | - Kenji Kangawa
- Department of BiochemistryNational Cerebral and Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan
| | - Mikiya Miyazato
- Department of BiochemistryNational Cerebral and Cardiovascular Center Research Institute, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan
| |
Collapse
|
30
|
Sárvári M, Kocsis P, Deli L, Gajári D, Dávid S, Pozsgay Z, Hegedűs N, Tihanyi K, Liposits Z. Ghrelin modulates the fMRI BOLD response of homeostatic and hedonic brain centers regulating energy balance in the rat. PLoS One 2014; 9:e97651. [PMID: 24830778 PMCID: PMC4022590 DOI: 10.1371/journal.pone.0097651] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 04/22/2014] [Indexed: 12/22/2022] Open
Abstract
The orexigenic gut-brain peptide, ghrelin and its G-protein coupled receptor, the growth hormone secretagogue receptor 1a (GHS-R1A) are pivotal regulators of hypothalamic feeding centers and reward processing neuronal circuits of the brain. These systems operate in a cooperative manner and receive a wide array of neuronal hormone/transmitter messages and metabolic signals. Functional magnetic resonance imaging was employed in the current study to map BOLD responses to ghrelin in different brain regions with special reference on homeostatic and hedonic regulatory centers of energy balance. Experimental groups involved male, ovariectomized female and ovariectomized estradiol-replaced rats. Putative modulation of ghrelin signaling by endocannabinoids was also studied. Ghrelin-evoked effects were calculated as mean of the BOLD responses 30 minutes after administration. In the male rat, ghrelin evoked a slowly decreasing BOLD response in all studied regions of interest (ROI) within the limbic system. This effect was antagonized by pretreatment with GHS-R1A antagonist JMV2959. The comparison of ghrelin effects in the presence or absence of JMV2959 in individual ROIs revealed significant changes in the prefrontal cortex, nucleus accumbens of the telencephalon, and also within hypothalamic centers like the lateral hypothalamus, ventromedial nucleus, paraventricular nucleus and suprachiasmatic nucleus. In the female rat, the ghrelin effects were almost identical to those observed in males. Ovariectomy and chronic estradiol replacement had no effect on the BOLD response. Inhibition of the endocannabinoid signaling by rimonabant significantly attenuated the response of the nucleus accumbens and septum. In summary, ghrelin can modulate hypothalamic and mesolimbic structures controlling energy balance in both sexes. The endocannabinoid signaling system contributes to the manifestation of ghrelin's BOLD effect in a region specific manner. In females, the estradiol milieu does not influence the BOLD response to ghrelin.
Collapse
Affiliation(s)
- Miklós Sárvári
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- * E-mail:
| | - Pál Kocsis
- Preclinical Imaging Center, Gedeon Richter Ltd., Budapest, Hungary
| | - Levente Deli
- Preclinical Imaging Center, Gedeon Richter Ltd., Budapest, Hungary
| | - Dávid Gajári
- Preclinical Imaging Center, Gedeon Richter Ltd., Budapest, Hungary
| | - Szabolcs Dávid
- Preclinical Imaging Center, Gedeon Richter Ltd., Budapest, Hungary
| | - Zsófia Pozsgay
- Preclinical Imaging Center, Gedeon Richter Ltd., Budapest, Hungary
| | - Nikolett Hegedűs
- Preclinical Imaging Center, Gedeon Richter Ltd., Budapest, Hungary
| | - Károly Tihanyi
- Preclinical Imaging Center, Gedeon Richter Ltd., Budapest, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary
| |
Collapse
|
31
|
Stoyanova II, le Feber J. Ghrelin accelerates synapse formation and activity development in cultured cortical networks. BMC Neurosci 2014; 15:49. [PMID: 24742241 PMCID: PMC3998954 DOI: 10.1186/1471-2202-15-49] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 04/14/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND While ghrelin was initially related to appetite stimulation and growth hormone secretion, it also has a neuroprotective effect in neurodegenerative diseases and regulates cognitive function. The cellular basis of those processes is related to synaptic efficacy and plasticity. Previous studies have shown that ghrelin not only stimulates synapse formation in cultured cortical neurons and hippocampal slices, but also alters some of the electrophysiological properties of neurons in the hypothalamus, amygdala and other subcortical areas. However, direct evidence for ghrelin's ability to modulate the activity in cortical neurons is not available yet. In this study, we investigated the effect of acylated ghrelin on the development of the activity level and activity patterns in cortical neurons, in relation to its effect on synaptogenesis. Additionally, we quantitatively evaluated the expression of the receptor for acylated ghrelin--growth hormone secretagogue receptor-1a (GHSR-1a) during development. RESULTS We performed electrophysiology and immunohistochemistry on dissociated cortical cultures from neonates, treated chronically with acylated ghrelin. On average 76±4.6% of the cortical neurons expressed GHSR-1a. Synapse density was found to be much higher in ghrelin treated cultures than in controls across all age groups (1, 2 or 3 weeks). In all cultures (control and ghrelin treated), network activity gradually increased until it reached a maximum after approximately 3 weeks, followed by a slight decrease towards a plateau. During early developmental stages (1-2 weeks), the activity was much higher in ghrelin treated cultures and consequently, they reached the plateau value almost a week earlier than controls. CONCLUSIONS Acylated ghrelin leads to earlier network formation and activation in cultured cortical neuronal networks, the latter being a possibly consequence of accelerated synaptogenesis.
Collapse
Affiliation(s)
- Irina I Stoyanova
- Biomedical Signals and Systems, Faculty of Electrical Engineering, Mathematics and Computer Sciences, Institute for Biomedical Engineering and Technical Medicine MIRA, BSS, ZH 226, University of Twente, P,O, Box 217, Enschede 7500 AE, The Netherlands.
| | | |
Collapse
|
32
|
Ariyasu H, Yamada G, Iwakura H, Matsumura S, Inoue K, Kangawa K, Nakao K, Akamizu T. Reduction in circulating ghrelin concentration after maturation does not affect food intake. Endocr J 2014; 61:1041-52. [PMID: 25029956 DOI: 10.1507/endocrj.ej14-0255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Ghrelin has a potent orexigenic effect and induces adiposity when administered exogenously. Since plasma ghrelin levels rise before meals, ghrelin was thought to play a crucial role in the regulation of appetite. In contrast, mice deficient in the production of ghrelin or the corresponding receptor, GHS-R, do not eat less, throwing the role of ghrelin in the regulation of energy homeostasis into question. Since these mice lack ghrelin or GHS-R from the time of conception, the possibility that compensatory mechanisms may have arisen during development cannot be ruled out. In this study, we used a transgenic mouse model that expresses human diphtheria toxin (DT) receptor cDNA under the control of the ghrelin promoter (GPDTR-Tg mice). As previously reported, an injection of DT into this mouse model ablates ghrelin-secreting cells in the stomach but not in the hypothalamus, resulting in a reduction in circulating ghrelin levels. We used this model system to evaluate the physiological roles of circulating ghrelin in the regulation of food intake. Meal patterns, diurnal and nocturnal meal sizes, and cumulative food intake of DT-treated GPDTR-Tg mice were not affected, although circulating ghrelin levels markedly decreased even after fasting. These mice also displayed normal responses to starvation; however, the use of fat increased and slower weight gain when maintained on a high fat diet was observed. Together, these data suggest that circulating ghrelin does not play a crucial role in feeding behavior, but rather is involved in maintaining body weight.
Collapse
Affiliation(s)
- Hiroyuki Ariyasu
- Department of Endocrinology and Metabolism, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Ghrelin but not nesfatin-1 affects certain forms of learning and memory in both rats and mice. Brain Res 2013; 1541:42-51. [DOI: 10.1016/j.brainres.2013.10.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 10/09/2013] [Accepted: 10/13/2013] [Indexed: 12/16/2022]
|
34
|
Ghrelin administration enhances neurogenesis but impairs spatial learning and memory in adult mice. Neuroscience 2013; 257:175-85. [PMID: 24211302 DOI: 10.1016/j.neuroscience.2013.10.063] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 10/11/2013] [Accepted: 10/25/2013] [Indexed: 12/11/2022]
Abstract
Ghrelin, an orexigenic brain-gut hormone promoting feeding and regulating energy metabolism in human and rodents, was reported to enhance both adult neurogenesis and hippocampus-dependent memory formation. However, it is still unclear whether ghrelin-induced hippocampus neurogenesis is responsible for its memory improvement. Using 5-bromo-2' deoxyuridien (BrdU) to birth-date newborn neurons and c-Fos expression to identify dentate gyrus (DG) neurons involved in memory processes, we checked here the effect of ghrelin treatment on adult neurogenesis and cognitive behaviors in mice. We further examined the possible effect of ghrelin on the recruitment of new neurons into the spatial memory traces in intact mice. We found that systemic ghrelin treatment (80μg/kg, ip injection once daily for 8days) stimulated neurogenesis in the adult hippocampus, but had no effect on spatial memory formation. Consistently, it did not affect the incorporation of newborn neurons into the spatial memory circuits. On the contrary, local infusion of ghrelin (8ng/0.5μl into CA1 region of the hippocampus) impaired spatial memory formation, but did not affect adult neurogenesis. Our results thus suggested that ghrelin plays distinct roles in modulating adult neurogenesis and the memory acquisition in the hippocampus, the two processes may not be correlated and may be mediated by different mechanisms.
Collapse
|
35
|
Lamont EW, Bruton J, Blum ID, Abizaid A. Ghrelin receptor-knockout mice display alterations in circadian rhythms of activity and feeding under constant lighting conditions. Eur J Neurosci 2013; 39:207-17. [DOI: 10.1111/ejn.12390] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 09/16/2013] [Indexed: 12/01/2022]
Affiliation(s)
- E. Waddington Lamont
- Department of Neuroscience; Carleton University; 1125 Colonel By Drive Ottawa ON K1S 5B6 Canada
- Department of Psychology; Thompson Rivers University; Kamloops BC Canada
| | - J. Bruton
- Department of Neuroscience; Carleton University; 1125 Colonel By Drive Ottawa ON K1S 5B6 Canada
| | - I. D. Blum
- Department of Neuroscience; Carleton University; 1125 Colonel By Drive Ottawa ON K1S 5B6 Canada
| | - A. Abizaid
- Department of Neuroscience; Carleton University; 1125 Colonel By Drive Ottawa ON K1S 5B6 Canada
| |
Collapse
|
36
|
Mason BL, Wang Q, Zigman JM. The central nervous system sites mediating the orexigenic actions of ghrelin. Annu Rev Physiol 2013; 76:519-33. [PMID: 24111557 DOI: 10.1146/annurev-physiol-021113-170310] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The peptide hormone ghrelin is important for both homeostatic and hedonic eating behaviors, and its orexigenic actions occur mainly via binding to the only known ghrelin receptor, the growth hormone secretagogue receptor (GHSR). GHSRs are located in several distinct regions of the central nervous system. This review discusses those central nervous system sites that have been found to play critical roles in the orexigenic actions of ghrelin, including hypothalamic nuclei, the hippocampus, the amygdala, the caudal brain stem, and midbrain dopaminergic neurons. Hopefully, this review can be used as a stepping stone for the reader wanting to gain a clearer understanding of the central nervous system sites of direct ghrelin action on feeding behavior, and as inspiration for future studies to provide an even-more-detailed map of the neurocircuitry controlling eating and body weight.
Collapse
Affiliation(s)
- B L Mason
- Departments of Internal Medicine (Divisions of Hypothalamic Research and of Endocrinology & Metabolism) and Psychiatry, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077; , ,
| | | | | |
Collapse
|
37
|
Cabral A, Fernandez G, Perello M. Analysis of brain nuclei accessible to ghrelin present in the cerebrospinal fluid. Neuroscience 2013; 253:406-15. [PMID: 24042041 DOI: 10.1016/j.neuroscience.2013.09.008] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 08/21/2013] [Accepted: 09/04/2013] [Indexed: 01/24/2023]
Abstract
Ghrelin is a stomach-derived peptide hormone that acts in the brain to regulate many important physiological functions. Ghrelin receptor, named the growth hormone secretagogue receptor (GHSR), is present in many brain areas with or without obvious direct access to ghrelin circulating in the bloodstream. Ghrelin is also present in the cerebrospinal fluid (CSF) but the brain targets of CSF ghrelin are unclear. Here, we studied which brain areas are accessible to ghrelin present in the CSF. For this purpose, we centrally injected mice with fluorescein-labeled ghrelin (F-ghrelin) peptide tracer and then systematically mapped the distribution of F-ghrelin signal through the brain. Our results indicated that centrally injected F-ghrelin labels neurons in most of the brain areas where GHSR is present. Also, we detected F-ghrelin uptake in the ependymal cells of both wild-type and GHSR-null mice. We conclude that CSF ghrelin is able to reach most of brain areas expressing GHSR. Also, we propose that the accessibility of CSF ghrelin to the brain parenchyma occurs through the ependymal cells in a GHSR-independent manner.
Collapse
Affiliation(s)
- A Cabral
- Laboratory of Neurophysiology of the Multidisciplinary Institute of Cell Biology, Argentine Research Council (CONICET) and Scientific Research Commission, La Plata, Province of Buenos Aires (CIC-PBA), Argentina
| | | | | |
Collapse
|
38
|
Stoyanova II, le Feber J, Rutten WL. Ghrelin stimulates synaptic formation in cultured cortical networks in a dose-dependent manner. ACTA ACUST UNITED AC 2013; 186:43-8. [DOI: 10.1016/j.regpep.2013.07.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Revised: 07/03/2013] [Accepted: 07/13/2013] [Indexed: 11/17/2022]
|
39
|
Bron R, Yin L, Russo D, Furness JB. Expression of the ghrelin receptor gene in neurons of the medulla oblongata of the rat. J Comp Neurol 2013; 521:2680-702. [DOI: 10.1002/cne.23309] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 12/12/2012] [Accepted: 01/17/2013] [Indexed: 01/29/2023]
Affiliation(s)
- Romke Bron
- Department of Anatomy & Neuroscience; University of Melbourne; Parkville; Victoria 3010; Australia
| | - Lei Yin
- Department of Anatomy & Neuroscience; University of Melbourne; Parkville; Victoria 3010; Australia
| | - Domenico Russo
- Department of Veterinary Morphophysiology and Animal Production; University of Bologna; 40064 Ozzano Emilia; Bologna; Italy
| | - John B. Furness
- Department of Anatomy & Neuroscience; University of Melbourne; Parkville; Victoria 3010; Australia
| |
Collapse
|
40
|
Song L, Zhu Q, Liu T, Yu M, Xiao K, Kong Q, Zhao R, Li GD, Zhou Y. Ghrelin modulates lateral amygdala neuronal firing and blocks acquisition for conditioned taste aversion. PLoS One 2013; 8:e65422. [PMID: 23762368 PMCID: PMC3676403 DOI: 10.1371/journal.pone.0065422] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 04/24/2013] [Indexed: 12/31/2022] Open
Abstract
Ghrelin is an orexigenic brain-gut hormone promoting feeding and regulating energy metabolism in human and rodents. An increasing number of studies have reported that ghrelin and its identified receptor, the growth hormone secretagogue receptor 1a (GHS-R1a), produces remarkably wide and complex functions and biological effects on specific populations of neurons in central nervous system. In this study, we sought to explore the in vivo effects of acute ghrelin exposure on lateral amygdala (LA) neurons at the physiological and behavioral levels. In vivo extracellular single-unit recordings showed that ghrelin with the concentration of several nanomolars (nM) stimulated spontaneous firing of the LA neurons, an effect that was dose-dependent and could be blocked by co-application of a GHS-R1a antagonist D-Lys3-GHRP-6. We also found that D-Lys3-GHRP-6 inhibited spontaneous firing of the LA neurons in a dose-dependent manner, revealing that tonic GHS-R1a activity contributes to orchestrate the basal activity of the LA neurons. Behaviorally, we found that microinfusion of ghrelin (12 ng) into LA before training interfered with the acquisition of conditioned taste aversion (CTA) as tested at 24 h after conditioning. Pre-treatment with either purified IgG against GHS-R1a or GHS-R1a antagonist blocked ghrelin’s effect on CTA memory acquisition. Ghrelin (12 ng) had no effect on CTA memory consolidation or the expression of acquired CTA memory; neither did it affect the total liquid consumption of tested rats. Altogether, our data indicated that ghrelin locally infused into LA blocks acquisition of CTA and its modulation effects on neuronal firing may be involved in this process.
Collapse
Affiliation(s)
- Lige Song
- Department of Physiology, Medical College of Qingdao University, Qingdao, Shandong, China
- Department of Neurology, Medical College Affiliated General Hospital, Qingdao, Shandong, China
| | - Qianqian Zhu
- Department of Physiology, Medical College of Qingdao University, Qingdao, Shandong, China
| | - Tianwei Liu
- Department of Physiology, Medical College of Qingdao University, Qingdao, Shandong, China
- Research Institute of Cerebrovascular Diseases, Medical College of Qingdao University, Qingdao, Shandong, China
| | - Ming Yu
- Department of Physiology, Medical College of Qingdao University, Qingdao, Shandong, China
| | - Kewei Xiao
- Department of Physiology, Medical College of Qingdao University, Qingdao, Shandong, China
| | - Qingnuan Kong
- Department of Physiology, Medical College of Qingdao University, Qingdao, Shandong, China
| | - Renliang Zhao
- Department of Neurology, Medical College Affiliated General Hospital, Qingdao, Shandong, China
| | - Guo-Dong Li
- Department of Anesthesiology, Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail: (YZ); (GDL)
| | - Yu Zhou
- Department of Physiology, Medical College of Qingdao University, Qingdao, Shandong, China
- * E-mail: (YZ); (GDL)
| |
Collapse
|
41
|
The expression of GHS-R in primary neurons is dependent upon maturation stage and regional localization. PLoS One 2013; 8:e64183. [PMID: 23755116 PMCID: PMC3673981 DOI: 10.1371/journal.pone.0064183] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 04/12/2013] [Indexed: 01/03/2023] Open
Abstract
Ghrelin is a hormone with a crucial role in the regulation of appetite, regulation of inflammation, glucose metabolism and cell proliferation. In the brain ghrelin neurons are located in the cortex (sensorimotor area, cingular gyrus), and the fibres of ghrelin neurons in hypothalamus project directly to the dorsal vagal complex (DVC). Ghrelin binds the growth hormone secretagogue receptor (GHS-R) a G-protein-coupled receptor with a widespread tissue distribution, indeed these receptors are localized both in nonnervous, organs/tissues (i.e. adipose tissue, myocardium, adrenals, gonads, lung, liver, arteries, stomach, pancreas, thyroid, and kidney) as well as in central nervous system (CNS) and higher levels of expression in the pituitary gland and the hypothalamus and lower levels of expression in other organs, including brain. A GHS-R specific monoclonal antibody has been developed and characterized and through it we demonstrate that GHS-R is expressed in primary neurons and that its expression is dependent upon their developmental stage and shows differences according to the brain region involved, with a more pronounced expression in hippocampal rather than cortical neurons. A characterization of GHS-R within the central nervous system is of extreme importance in order to gain insights on its role in the modulation of neurodegenerative events such as Alzheimer’s disease.
Collapse
|
42
|
Kwon Jeong J, Dae Kim J, Diano S. Ghrelin regulates hypothalamic prolyl carboxypeptidase expression in mice. Mol Metab 2013; 2:23-30. [PMID: 24024131 DOI: 10.1016/j.molmet.2013.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 12/28/2012] [Accepted: 01/03/2013] [Indexed: 12/25/2022] Open
Abstract
Hypothalamic Prolyl carboxypeptidase (PRCP) plays a role in the regulation of energy metabolism by inactivating hypothalamic α-melanocyte stimulating hormone (α-MSH) levels and thus affecting melanocortin signaling. Alpha-MSH production is highly regulated both at transcriptional and posttranslational levels. Here we show that fasting induces a hypothalamic-specific up-regulation of Prcp mRNA and protein levels. Since fasting is characterized by elevated circulating ghrelin levels, we tested the effect of peripheral and central administration of ghrelin, and found that ghrelin increases hypothalamic Prcp mRNA expression. No changes in Prcp mRNA levels were detected in ghrelin knockout mice compared to their controls. Finally, ghrelin effect on PRCP expression was ghrelin receptor-mediated. Altogether our data show that ghrelin is a key regulator of hypothalamic PRCP expression, and up-regulation of PRCP by ghrelin may be an additional mechanism to decrease melanocortin signaling.
Collapse
Key Words
- (ARC), Arcuate nucleus
- (AgRP), Agouti related peptide
- (CTX), Cortex
- (DMH), Dorsomedial nucleus
- (GHS-R), Growth hormone secretagogue receptor
- (Hcrt), Hypocretin
- (LH), Lateral hypothalamus
- (MCH), Melanin concentrating hormone
- (NPY), Neuropeptide Y
- (POMC), Proopiomelanocortin
- (PRCP), Prolyl carboxypeptidase
- (Prcpgt/gt), Prcp-ablated mice
- (VMH), Ventromedial nucleus
- (α-MSH), α-Melanocyte stimulating hormone
- Alpha-melanocyte stimulating hormone
- Fasting
- Ghrelin
- Hypothalamus
- Prolyl carboxypeptidase
Collapse
Affiliation(s)
- Jin Kwon Jeong
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, New Haven, CT, 06520, USA ; Department of Ob/Gyn & Reproductive Sciences, New Haven, CT, 06520, USA
| | | | | |
Collapse
|
43
|
Abstract
Brain development is a complex and dynamic process, and many environmental factors have been found to influence the normal development of neural pathways. Cumulative evidence suggests that metabolic hormones that regulate the hypothalamic circuits that control energy homeostasis function in much the same way that sex steroids act on sexually dimorphic circuits. For example, although the effects of the adipocyte-derived hormone leptin were originally thought to be limited to the neural control of energy homeostasis in adult animals, it is now becoming increasingly clear that leptin can also determine patterns of neurogenesis, axon growth, and synaptic plasticity in the developing hypothalamus. More recent studies have also extended the role of the metabolic hormones ghrelin and insulin in various aspects of brain development. Examining how metabolic hormones control hypothalamic development will help our understanding of the developmental origin of adult metabolic diseases and, hopefully, improve our ability to predict adverse outcomes.
Collapse
Affiliation(s)
- Sebastien G Bouret
- The Saban Research Institute, Neuroscience Program, Children's Hospital Los Angeles, University of Southern California, Los Angeles, CA 90027, USA.
| |
Collapse
|
44
|
Abstract
Ghrelin was discovered in 1999 as growth hormone secretagouge released from the gut. Soon after it was recognized that ghrelin is a fundamental driver of appetite in rodents and humans and that its mode of action requires alteration of hypothalamic circuit function. Here we review aspects of ghrelin's action that revolve around the central nervous system with the goal to highlight these pathways in integrative physiology of metabolism regulation including ghrelin's cross-talk with the action of the adipose hormone, leptin.
Collapse
Affiliation(s)
- Alfonso Abizaid
- Department of Neuroscience, Carlton University, Ottawa, ON, Canada
| | - Tamas L. Horvath
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Section of Comparative Medicine, Yale University School of Medicine, New Haven, CT, USA
| |
Collapse
|
45
|
Szentirmai É. Central but not systemic administration of ghrelin induces wakefulness in mice. PLoS One 2012; 7:e41172. [PMID: 22815958 PMCID: PMC3398952 DOI: 10.1371/journal.pone.0041172] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 06/18/2012] [Indexed: 11/19/2022] Open
Abstract
Ghrelin is a brain-gut peptide hormone widely known for its orexigenic and growth hormone-releasing activities. Findings from our and other laboratories indicate a role of ghrelin in sleep regulation. The effects of exogenous ghrelin on sleep-wake activity in mice are, however, unknown. The aim of the present study was to determine the sleep-modulating effects of ghrelin after central and systemic administrations in mice. Sleep-wake activity after intracerebroventricular (i.c.v.) administration of 0.2, 1 and 5 µg ghrelin and intraperitoneal injections of 40, 100, and 400 µg/kg ghrelin prior to light onset were determined in C57BL/6 mice. In addition, body temperature, motor activity and 1-hour food intake was measured after the systemic injections. Sleep effects of systemic ghrelin (40 and 400 µg/kg) injected before dark onset were also determined. I.c.v. injection of ghrelin increased wakefulness and suppressed non-rapid-eye-movement sleep and electroencephalographic slow-wave activity in the first hour after injections. Rapid-eye-movement sleep was decreased for 2-4 hours after each dose of ghrelin. Sytemic administration of ghrelin did not induce changes in sleep-wake activity in mice at dark or light onset. Motor activity and body temperature remained unaltered and food intake was significantly increased after systemic injections of ghrelin given prior the light period. These findings indicate that the activation of central, but not peripheral, ghrelin-sensitive mechanisms elicits arousal in mice. The results are consistent with the hypothesis that the activation of the hypothalamic neuronal circuit formed by ghrelin, orexin, and neuropeptide Y neurons triggers behavioral sequence characterized by increased wakefulness, motor activity and feeding in nocturnal rodents.
Collapse
Affiliation(s)
- Éva Szentirmai
- Washington, Wyoming, Alaska, Montana and Idaho (WWAMI) Medical Education Program, Washington State University, Spokane, Washington, United States of America.
| |
Collapse
|
46
|
Perello M, Scott MM, Sakata I, Lee CE, Chuang JC, Osborne-Lawrence S, Rovinsky SA, Elmquist JK, Zigman JM. Functional implications of limited leptin receptor and ghrelin receptor coexpression in the brain. J Comp Neurol 2012; 520:281-94. [PMID: 21674492 DOI: 10.1002/cne.22690] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The hormones leptin and ghrelin act in apposition to one another in the regulation of body weight homeostasis. Interestingly, both leptin receptor expression and ghrelin receptor expression have been observed within many of the same nuclei of the central nervous system (CNS), suggesting that these hormones may act on a common population of neurons to produce changes in food intake and energy expenditure. In the present study we explored the extent of this putative direct leptin and ghrelin interaction in the CNS and addressed the question of whether a loss of ghrelin signaling would affect sensitivity to leptin. Using histological mapping of leptin receptor and ghrelin receptor expression, we found that cells containing both leptin receptors and ghrelin receptors are mainly located in the medial part of the hypothalamic arcuate nucleus. In contrast, coexpression was much less extensive elsewhere in the brain. To assess the functional consequences of this observed receptor distribution, we explored the effect of ghrelin receptor deletion on leptin sensitivity. In particular, the responses of ad libitum-fed, diet-induced obese and fasted mice to the anorectic actions of leptin were examined. Surprisingly, we found that deletion of the ghrelin receptor did not affect the sensitivity to exogenously administrated leptin. Thus, we conclude that ghrelin and leptin act largely on distinct neuronal populations and that ghrelin receptor deficiency does not affect sensitivity to the anorexigenic and body weight-lowering actions of leptin.
Collapse
Affiliation(s)
- Mario Perello
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Pellinen J, Szentirmai É. The effects of C75, an inhibitor of fatty acid synthase, on sleep and metabolism in mice. PLoS One 2012; 7:e30651. [PMID: 22348016 PMCID: PMC3278418 DOI: 10.1371/journal.pone.0030651] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 12/22/2011] [Indexed: 12/19/2022] Open
Abstract
Sleep is greatly affected by changes in metabolic state. A possible mechanism where energy-sensing and sleep-regulatory functions overlap is related to lipid metabolism. Fatty acid synthase (FAS) plays a central role in lipid metabolism as a key enzyme in the formation of long-chain fatty acids. We studied the effects of systemic administration of C75, an inhibitor of FAS, on sleep, behavioral activity and metabolic parameters in mice. Since the effects of C75 on feeding and metabolism are the opposite of ghrelin's and C75 suppresses ghrelin production, we also tested the role of ghrelin signaling in the actions of C75 by using ghrelin receptor knockout (KO) mice. After a transient increase in wakefulness, C75 elicited dose-dependent and long lasting inhibition of REMS, motor activity and feeding. Simultaneously, C75 significantly attenuated slow-wave activity of the electroencephalogram. Energy expenditure, body temperature and respiratory exchange ratio were suppressed. The diurnal rhythm of feeding was completely abolished by C75. There was significant correlation between the anorectic effects, the decrease in motor activity and the diminished energy expenditure after C75 injection. We found no significant difference between wild-type and ghrelin receptor KO mice in their sleep and metabolic responses to C75. The effects of C75 resemble to what was previously reported in association with visceral illness. Our findings suggest that sleep and metabolic effects of C75 in mice are independent of the ghrelin system and may be due to its aversive actions in mice.
Collapse
Affiliation(s)
- Jacob Pellinen
- Washington, Wyoming, Alaska, Montana and Idaho (WWAMI) Medical Education Program, Washington State University, Spokane, Washington, United States of America
| | - Éva Szentirmai
- Washington, Wyoming, Alaska, Montana and Idaho (WWAMI) Medical Education Program, Washington State University, Spokane, Washington, United States of America
- Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Spokane, Washington, United States of America
- Sleep and Performance Research Center, Washington State University, Spokane, Washington, United States of America
- * E-mail:
| |
Collapse
|
48
|
Blum I, Lamont EW, Abizaid A. Competing clocks: Metabolic status moderates signals from the master circadian pacemaker. Neurosci Biobehav Rev 2012; 36:254-70. [DOI: 10.1016/j.neubiorev.2011.06.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 05/27/2011] [Accepted: 06/02/2011] [Indexed: 11/28/2022]
|
49
|
Esposito M, Pellinen J, Kapás L, Szentirmai É. Impaired wake-promoting mechanisms in ghrelin receptor-deficient mice. Eur J Neurosci 2011; 35:233-43. [PMID: 22211783 DOI: 10.1111/j.1460-9568.2011.07946.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ghrelin receptors are expressed by key components of the arousal system. Exogenous ghrelin induces behavioral activation, promotes wakefulness and stimulates eating. We hypothesized that ghrelin-sensitive mechanisms play a role in the arousal system. To test this, we investigated the responsiveness of ghrelin receptor knockout (KO) mice to two natural wake-promoting stimuli. Additionally, we assessed the integrity of their homeostatic sleep-promoting system using sleep deprivation. There was no significant difference in the spontaneous sleep-wake activity between ghrelin receptor KO and wild-type (WT) mice. WT mice mounted robust arousal responses to a novel environment and food deprivation. Wakefulness increased for 6 h after cage change accompanied by increases in body temperature and locomotor activity. Ghrelin receptor KO mice completely lacked the wake and body temperature responses to new environment. When subjected to 48 h food deprivation, WT mice showed marked increases in their waking time during the dark periods of both days. Ghrelin receptor KO mice failed to mount an arousal response on the first night and wake increases were attenuated on the second day. The responsiveness to sleep deprivation did not differ between the two genotypes. These results indicate that the ghrelin-receptive mechanisms play an essential role in the function of the arousal system but not in homeostatic sleep-promoting mechanisms.
Collapse
Affiliation(s)
- Matthew Esposito
- Washington, Wyoming, Alaska, Montana and Idaho (WWAMI) Medical Education Program, Washington State University, PO Box 1495, Spokane, WA 99210-1495, USA
| | | | | | | |
Collapse
|
50
|
Skibicka KP, Dickson SL. Ghrelin and food reward: the story of potential underlying substrates. Peptides 2011; 32:2265-73. [PMID: 21621573 DOI: 10.1016/j.peptides.2011.05.016] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 05/11/2011] [Accepted: 05/12/2011] [Indexed: 10/18/2022]
Abstract
The incidence of obesity is increasing at an alarming rate and this worldwide epidemic represents a significant decrease in life span and quality of life of a large part of the affected population. Therefore an understanding of mechanisms underlying food overconsumption and obesity development is urgent and essential to find potential treatments. Research investigating mechanisms underlying obesity and the control of food intake has recently experienced a major shift in focus, from the brain's hypothalamus to additional important neural circuits controlling emotion, cognition and motivated behavior. Among them, the mesolimbic system, and the changes in reward and motivated behavior for food, emerge as new promising treatment targets. Furthermore, there is also growing appreciation of the impact of peripheral hormones that signal nutrition status to the mesolimbic areas, and especially the only known circulating orexigenic hormone, ghrelin. This review article provides a synthesis of recent evidence concerning the impact of manipulation of ghrelin and its receptor on models of food reward/food motivation behavior and the mesolimbic circuitry. Particular attention is given to the potential neurocircuitry and neurotransmitter systems downstream of ghrelin's effects on food reward.
Collapse
Affiliation(s)
- Karolina P Skibicka
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, SE-405 30 Gothenburg, Sweden.
| | | |
Collapse
|