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Pietrzak M, Yngve A, Hamilton JP, Asratian A, Gauffin E, Löfberg A, Gustavson S, Persson E, Capusan AJ, Leggio L, Perini I, Tinghög G, Heilig M, Boehme R. Ghrelin decreases sensitivity to negative feedback and increases prediction-error related caudate activity in humans, a randomized controlled trial. Neuropsychopharmacology 2024; 49:1042-1049. [PMID: 38409282 DOI: 10.1038/s41386-024-01821-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 02/01/2024] [Accepted: 02/04/2024] [Indexed: 02/28/2024]
Abstract
The stomach-derived hormone ghrelin plays not only a role in feeding, starvation, and survival, but it has been suggested to also be involved in the stress response, in neuropsychiatric conditions, and in alcohol and drug use disorders. Mechanisms related to reward processing might mediate ghrelin's broader effects on complex behaviors, as indicated by animal studies and mostly correlative human studies. Here, using a within-subject double-blind placebo-controlled design with intravenous ghrelin infusion in healthy volunteers (n = 30), we tested whether ghrelin alters sensitivity to reward and punishment in a reward learning task. Parameters were derived from a computational model of participants' task behavior. The reversal learning task with monetary rewards was performed during functional brain imaging to investigate ghrelin effects on brain signals related to reward prediction errors. Compared to placebo, ghrelin decreased punishment sensitivity (t = -2.448, p = 0.021), while reward sensitivity was unaltered (t = 0.8, p = 0.43). We furthermore found increased prediction-error related activity in the dorsal striatum during ghrelin administration (region of interest analysis: t-values ≥ 4.21, p-values ≤ 0.044). Our results support a role for ghrelin in reward processing that extends beyond food-related rewards. Reduced sensitivity to negative outcomes and increased processing of prediction errors may be beneficial for food foraging when hungry but could also relate to increased risk taking and impulsivity in the broader context of addictive behaviors.
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Affiliation(s)
- Michal Pietrzak
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, 58183, Sweden
- Department of Psychiatry, Linköping University Hospital, Linköping, 58183, Sweden
- Center for Medical Imaging and Visualization, Linköping University, Linköping, 58183, Sweden
| | - Adam Yngve
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, 58183, Sweden
- Center for Medical Imaging and Visualization, Linköping University, Linköping, 58183, Sweden
| | - J Paul Hamilton
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, 58183, Sweden
- Center for Medical Imaging and Visualization, Linköping University, Linköping, 58183, Sweden
- Department of Medical and Biological Psychology, University of Bergen, Bergen, 5007, Norway
| | - Anna Asratian
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, 58183, Sweden
- Center for Medical Imaging and Visualization, Linköping University, Linköping, 58183, Sweden
| | - Emelie Gauffin
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, 58183, Sweden
- Department of Psychiatry, Linköping University Hospital, Linköping, 58183, Sweden
- Center for Medical Imaging and Visualization, Linköping University, Linköping, 58183, Sweden
| | - Andreas Löfberg
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, 58183, Sweden
- Department of Psychiatry, Linköping University Hospital, Linköping, 58183, Sweden
- Center for Medical Imaging and Visualization, Linköping University, Linköping, 58183, Sweden
| | - Sarah Gustavson
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, 58183, Sweden
- Department of Psychiatry, Linköping University Hospital, Linköping, 58183, Sweden
- Center for Medical Imaging and Visualization, Linköping University, Linköping, 58183, Sweden
| | - Emil Persson
- Division of Economics, Department of Management and Engineering, Linköping University, Linköping, 58183, Sweden
| | - Andrea J Capusan
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, 58183, Sweden
- Department of Psychiatry, Linköping University Hospital, Linköping, 58183, Sweden
| | - Lorenzo Leggio
- Section on Clinical Psychoneuroendocrinology and Neuropsychopharmacology, Translational Addiction Medicine Branch, National Institute on Drug Abuse Intramural Research Program and National Institute on Alcohol Abuse and Alcoholism, Division of Intramural Clinical and Biological Research, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Irene Perini
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, 58183, Sweden
- Center for Medical Imaging and Visualization, Linköping University, Linköping, 58183, Sweden
| | - Gustav Tinghög
- Division of Economics, Department of Management and Engineering, Linköping University, Linköping, 58183, Sweden
- National Center for Health Care Priority Setting, Department of Health Medicine and Caring Sciences, Linköping University, 58183, Linköping, Sweden
| | - Markus Heilig
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, 58183, Sweden
- Department of Psychiatry, Linköping University Hospital, Linköping, 58183, Sweden
- Center for Medical Imaging and Visualization, Linköping University, Linköping, 58183, Sweden
| | - Rebecca Boehme
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, 58183, Sweden.
- Center for Medical Imaging and Visualization, Linköping University, Linköping, 58183, Sweden.
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Chen Y, Li H, Kong T, Shan L, Hao L, Wang F. The low ratio of ghrelin in plasma and cerebrospinal fluid might be beneficial to sleep. Pharmacol Biochem Behav 2023; 233:173672. [PMID: 37944671 DOI: 10.1016/j.pbb.2023.173672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/30/2023] [Accepted: 11/01/2023] [Indexed: 11/12/2023]
Abstract
OBJECTIVE Ghrelin is physiologically important for maintaining sleep rhythm. Cigarette smoking has been demonstrated to significantly increase the risk of insufficient sleep by regulating ghrelin at the central and peripheral levels. No research has been published to study the relationship between active smoking and sleep via ghrelin level in cerebrospinal fluid (CSF). METHODS A total of 139 Chinese males were recruited and divided into active smokers (n = 77) and non-smokers (n = 62). The levels of CSF and plasma ghrelin were measured. The Pittsburgh Sleep Quality Index (PSQI) was used to evaluate sleep. RESULTS Non-smokers had lower PSQI scores (1.71 ± 1.93) than active smokers (3.70 ± 1.78). Non-smokers have significantly lower plasma ghrelin levels and lower plasma/CSF ghrelin ratio but higher CSF ghrelin than active smokers. Among non-smokers, plasma ghrelin levels were not correlated with PSQI scores (all p > 0.05), CSF ghrelin levels were positively correlated with PSQI scores (r = 0.309, p = 0.019), and the plasma/CSF ghrelin ratio was negatively correlated with PSQI scores (r = -0.346, p = 0.008). CONCLUSIONS This study is the first to reveal the relationship between cigarette smoking, high CSF ghrelin levels and insufficient sleep, suggesting that maintaining a normal plasma/CSF ghrelin ratio may be the physiological mechanism of healthy sleep, and the insufficient sleep population must quit smoking.
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Affiliation(s)
- Yuanyuan Chen
- Medical Neurobiology Lab, Inner Mongolia Medical University, Huhhot 010110, China
| | - Hui Li
- Department of Biomedical Engineering, College of Future Technology, Peking University, Beijing 100871, China
| | - Tiantian Kong
- Xinjiang Key Laboratory of Neurological Disorder Research, the Second Affiliated Hospital of Xinjiang Medical University, Urumqi 830063, China
| | - Ligang Shan
- Department of Anesthesiology, the Second Affiliated Hospital of Xiamen Medical College, Xiamen 361021, China
| | - Lei Hao
- Medical Neurobiology Lab, Inner Mongolia Medical University, Huhhot 010110, China.
| | - Fan Wang
- Beijing Hui-Long-Guan Hospital, Peking University, Beijing 100096, China.
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Álvarez-Vásquez JL, Bravo-Guapisaca MI, Gavidia-Pazmiño JF, Intriago-Morales RV. Adipokines in dental pulp: physiological, pathological, and potential therapeutic roles. J Oral Biosci 2021; 64:59-70. [PMID: 34808362 DOI: 10.1016/j.job.2021.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 11/12/2021] [Accepted: 11/15/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND Hundreds of adipokines have been identified, and their extensive range of endocrine functions-regulating distant organs such as oral tissues-and local autocrine/paracrine roles have been studied. In dentistry, however, adipokines are poorly known proteins in the dental pulp; few of them have been studied despite their large number. This study reviews recent advances in the investigation of dental-pulp adipokines, with an emphasis on their roles in inflammatory processes and their potential therapeutic applications. HIGHLIGHTS The most recently identified adipokines in dental pulp include leptin, adiponectin, resistin, ghrelin, oncostatin, chemerin, and visfatin. They have numerous physiological and pathological functions in the pulp tissue: they are closely related to pulp inflammatory mechanisms and actively participate in cell differentiation, mineralization, angiogenesis, and immune-system modulation. CONCLUSION Adipokines have potential clinical applications in regenerative endodontics and as biomarkers or targets for the pharmacological management of inflammatory and degenerative processes in dental pulp. A promising direction for the development of new therapies may be the use of agonists/antagonists to modulate the expression of the most studied adipokines.
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van Loenen MR, Geenen B, Arnoldussen IAC, Kiliaan AJ. Ghrelin as a prominent endocrine factor in stress-induced obesity. Nutr Neurosci 2020; 25:1413-1424. [PMID: 33373270 DOI: 10.1080/1028415x.2020.1863740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Objectives: Ghrelin acts on a variety of central- and peripheral organs causing an orexigenic effect, conclusively followed by increased caloric intake. Recent studies have indicated that ghrelin's function as an orexigenic agent does not entirely reflect the full functional properties of the peptide. Specifically, ghrelin regulates stress-hormone synthesis and secretion therewith affecting the stress-axis. The role of stress in the development of obesity has been extensively studied. However, the orexigenic and underlying stress-regulatory effect of ghrelin has not yet been further considered in the development of stress-induced obesity.Methods: Therefore, this review aims to accentuate the potential of ghrelin as a factor in the pathological development of stress-induced obesity.Results: In this review we discuss (1) the ghrelin-mediated intracellular cascades and elucidate the overall bioactivation of the peptide, and (2) the mechanisms of ghrelin signalling and regulation within the central nervous system and the gastro-intestinal system.Discussion: These biological processes will be ultimately discussed in relation to the pathogenesis of stress-induced obesity.
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Affiliation(s)
- Mark R van Loenen
- Department of Medical Imaging, Anatomy, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Preclinical Imaging Center PRIME, Nijmegen, Netherlands
| | - Bram Geenen
- Department of Medical Imaging, Anatomy, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Preclinical Imaging Center PRIME, Nijmegen, Netherlands
| | - Ilse A C Arnoldussen
- Department of Medical Imaging, Anatomy, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Preclinical Imaging Center PRIME, Nijmegen, Netherlands
| | - Amanda J Kiliaan
- Department of Medical Imaging, Anatomy, Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Preclinical Imaging Center PRIME, Nijmegen, Netherlands
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Perello M, Cabral A, Cornejo MP, De Francesco PN, Fernandez G, Uriarte M. Brain accessibility delineates the central effects of circulating ghrelin. J Neuroendocrinol 2019; 31:e12677. [PMID: 30582239 DOI: 10.1111/jne.12677] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 12/04/2018] [Accepted: 12/04/2018] [Indexed: 12/27/2022]
Abstract
Ghrelin is a hormone produced in the gastrointestinal tract that acts via the growth hormone secretagogue receptor. In the central nervous system, ghrelin signalling is able to recruit different neuronal targets that regulate the behavioural, neuroendocrine, metabolic and autonomic effects of the hormone. Notably, several studies using radioactive or fluorescent variants of ghrelin have found that the accessibility of circulating ghrelin into the mouse brain is both strikingly low and restricted to some specific brain areas. A variety of studies addressing central effects of systemically injected ghrelin in mice have also provided indirect evidence that the accessibility of plasma ghrelin into the brain is limited. Here, we review these previous observations and discuss the putative pathways that would allow plasma ghrelin to gain access into the brain together with their physiological implications. Additionally, we discuss some potential features regarding the accessibility of plasma ghrelin into the human brain based on the observations reported by studies that investigate the consequences of ghrelin administration to humans.
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Affiliation(s)
- Mario Perello
- Laboratorio de Neurofisiología del Instituto Multidisciplinario de Biología Celular, Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Universidad Nacional de La Plata y Comisión de Investigaciones Científicas-Provincia de Buenos Aires, Buenos Aires, Argentina
| | - Agustina Cabral
- Laboratorio de Neurofisiología del Instituto Multidisciplinario de Biología Celular, Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Universidad Nacional de La Plata y Comisión de Investigaciones Científicas-Provincia de Buenos Aires, Buenos Aires, Argentina
| | - María P Cornejo
- Laboratorio de Neurofisiología del Instituto Multidisciplinario de Biología Celular, Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Universidad Nacional de La Plata y Comisión de Investigaciones Científicas-Provincia de Buenos Aires, Buenos Aires, Argentina
| | - Pablo N De Francesco
- Laboratorio de Neurofisiología del Instituto Multidisciplinario de Biología Celular, Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Universidad Nacional de La Plata y Comisión de Investigaciones Científicas-Provincia de Buenos Aires, Buenos Aires, Argentina
| | - Gimena Fernandez
- Laboratorio de Neurofisiología del Instituto Multidisciplinario de Biología Celular, Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Universidad Nacional de La Plata y Comisión de Investigaciones Científicas-Provincia de Buenos Aires, Buenos Aires, Argentina
| | - Maia Uriarte
- Laboratorio de Neurofisiología del Instituto Multidisciplinario de Biología Celular, Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina, Universidad Nacional de La Plata y Comisión de Investigaciones Científicas-Provincia de Buenos Aires, Buenos Aires, Argentina
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Clarifying the Ghrelin System's Ability to Regulate Feeding Behaviours Despite Enigmatic Spatial Separation of the GHSR and Its Endogenous Ligand. Int J Mol Sci 2017; 18:ijms18040859. [PMID: 28422060 PMCID: PMC5412441 DOI: 10.3390/ijms18040859] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 04/04/2017] [Accepted: 04/11/2017] [Indexed: 12/23/2022] Open
Abstract
Ghrelin is a hormone predominantly produced in and secreted from the stomach. Ghrelin is involved in many physiological processes including feeding, the stress response, and in modulating learning, memory and motivational processes. Ghrelin does this by binding to its receptor, the growth hormone secretagogue receptor (GHSR), a receptor found in relatively high concentrations in hypothalamic and mesolimbic brain regions. While the feeding and metabolic effects of ghrelin can be explained by the effects of this hormone on regions of the brain that have a more permeable blood brain barrier (BBB), ghrelin produced within the periphery demonstrates a limited ability to reach extrahypothalamic regions where GHSRs are expressed. Therefore, one of the most pressing unanswered questions plaguing ghrelin research is how GHSRs, distributed in brain regions protected by the BBB, are activated despite ghrelin’s predominant peripheral production and poor ability to transverse the BBB. This manuscript will describe how peripheral ghrelin activates central GHSRs to encourage feeding, and how central ghrelin synthesis and ghrelin independent activation of GHSRs may also contribute to the modulation of feeding behaviours.
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Yu J, Xu H, Shen X, Jiang H. Ghrelin protects MES23.5 cells against rotenone via inhibiting mitochondrial dysfunction and apoptosis. Neuropeptides 2016; 56:69-74. [PMID: 26459609 DOI: 10.1016/j.npep.2015.09.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 09/25/2015] [Accepted: 09/29/2015] [Indexed: 12/21/2022]
Abstract
Ghrelin is an endogenous ligand for the growth hormone secretagogue (GHS) receptor and has several important physiological functions. Recently, particular attention has been paid to its neuroprotective effect. Rotenone is used to investigate the pathogenesis of Parkinson's disease (PD) for its ability to inhibit mitochondrial complex I. The current study was carried out to investigate the neuroprotective effects of ghrelin against rotenone in MES 23.5 dopaminergic cells and explored the possible mechanisms underlying this protection. Our results showed that rotenone induced significant decrease in cell viability which was counteracted by ghrelin treatment. In addition, rotenone challenge reduced mitochondrial membrane potential, inhibited the activity of mitochondrial complex I and depressed cytochrome C release from mitochondria. This mitochondrial dysfunction was reversed by ghrelin treatment. Furthermore, our results demonstrated that ghrelin protected MES23.5 cells against rotenone-induced apoptosis by inhibiting activation of caspase-3. Overall, our findings showed ghrelin provided protective effects on MES23.5 dopaminergic cells against rotenone via restoring mitochondrial dysfunction and inhibiting mitochondrial dependent apoptosis.
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Affiliation(s)
- Jianhan Yu
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Medical College of Qingdao University, Qingdao, 266071, China
| | - Huamin Xu
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Medical College of Qingdao University, Qingdao, 266071, China
| | - Xiaoli Shen
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Medical College of Qingdao University, Qingdao, 266071, China
| | - Hong Jiang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Medical College of Qingdao University, Qingdao, 266071, China.
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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.
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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
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Orts-Del'immagine A, Wanaverbecq N, Tardivel C, Tillement V, Dallaporta M, Trouslard J. Properties of subependymal cerebrospinal fluid contacting neurones in the dorsal vagal complex of the mouse brainstem. J Physiol 2012; 590:3719-41. [PMID: 22570378 DOI: 10.1113/jphysiol.2012.227959] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cerebrospinal fluid (CSF) contacting neurones have been observed in various brain regions such as the hypothalamus, the dorsal nucleus of the raphe and around the central canal (cc) of the spinal cord but their functional role remains unclear. At the level of the spinal cord, subependymal cerebrospinal fluid contacting neurones (S-CSF-cNs) present a peculiar morphology with a soma close to the ependymal layer, a process projecting towards the cc and ending with a bud and a cilium. These neurones were recently shown to express polycystin kidney disease 2-like 1 (PKD2L1 or TRPP3) channels that are members of the polycystin subtype of the transient receptor potential (TRP) channel superfamily and that have been proposed as either chemo- or mechanoreceptors in several tissues. Using immunohistological techniques and whole-cell electrophysiological recordings in brain slices obtained from PKD2L1:EGFP transgenic adult mice, we looked for and determined the functional properties of S-CSF-cNs in the dorsal vagal complex (DVC), a hindbrain structure controlling autonomic functions such as blood pressure, energy balance and food intake. Here, we demonstrate that S-CSF-cNs received GABAergic and/or glycinergic synaptic entries and were also characterised by the presence of non-selective cationic channels of large conductance that could be detected even under whole-cell configuration. The channel activity was not affected by Psalmopoeus cambridgei toxin 1, a blocker of acid sensing ion channels (ASICs), but was blocked by amiloride and by a strong extracellular acidification. In contrast, extracellular alkalinisation and hypo-osmotic shocks increased channel activity. Based on these properties, we suggest that the single-channel activity recorded in medullar S-CSF-cNs is carried by PKD2L1 channels. Our study therefore reinforces the idea that PKD2L1 is a marker of S-CSF-cNs and points toward a role for S-CSF-cNs in the detection of circulating signals and of modifications in the extracellular environment.
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Affiliation(s)
- Adeline Orts-Del'immagine
- Laboratoire de Physiologie et Physiopathologie du Système Nerveux Somato-moteur et Neurovégétatif (PPSN) EA 4674 Aix-Marseille Université (AMU), Faculté des Sciences et Techniques St. Jérôme, BP 352, Avenue Escadrille Normandie Niemen, F-13397 Marseille cedex 20, France
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Tang B, Chen J, Yao Q, Pan Z, Xu W, Wang S, Zhang W. Characterization of a trehalose-6-phosphate synthase gene from Spodoptera exigua and its function identification through RNA interference. JOURNAL OF INSECT PHYSIOLOGY 2010; 56:813-821. [PMID: 20193689 DOI: 10.1016/j.jinsphys.2010.02.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 02/12/2010] [Accepted: 02/12/2010] [Indexed: 05/28/2023]
Abstract
Trehalose is an important disaccharide and a key regulation factor for the development of many organisms, including plants, bacteria, fungi and insects. In order to study the trehalose synthesis pathway, a cDNA for a trehalose-6-phosphate synthase from Spodoptera exigua (SeTPS) was cloned which contained an open reading frame of 2481 nucleotides encoding a protein of 826 amino acids with a predicted molecular weight of 92.65kDa. The SeTPS genome has 12 exons and 11 introns. Northern blot and RT-PCR analyses showed that SeTPS mRNA was expressed in the fat body and in the ovary. Competitive RT-PCR revealed that SeTPS mRNA was expressed in the fat body at different developmental stages and was present at a high level in day 1 S. exigua pupae. The concentrations of trehalose and glucose in the hemolymph were determined by HPLC and showed that they varied at different developmental stages and were negatively correlated to each other. The survival rates of the insects injected with dsRNA corresponding to SeTPS gene reached 53.95%, 49.06%, 34.86% and 33.24% for 36, 48, 60 and 204h post-injection respectively which were significantly lower than those of the insects in three control groups. These findings provide new data on the tissue distribution, expression patterns and potential function of the trehalose-6-phosphate synthase gene.
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Affiliation(s)
- Bin Tang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong 510275, China
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Plasma ghrelin levels and polymorphisms of ghrelin gene in Chinese obese children and adolescents. Ir J Med Sci 2010; 179:345-9. [PMID: 20517652 DOI: 10.1007/s11845-010-0494-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 05/03/2010] [Indexed: 10/19/2022]
Abstract
AIM To evaluate the role of fasting plasma ghrelin levels [ln(ghrelin)] and polymorphisms of ghrelin gene in Chinese obese children. METHODS Genotyping for ghrelin polymorphism was performed in 230 obese and 100 normal weight children. Among them, plasma ghrelin levels were measured in 91 obese and 23 health subjects. RESULTS (1) Bivariate correlation analysis showed the ln(ghrelin) was inversely correlated with abnormality of glucose metabolism (r = -0.240, P = 0.023). Stepwise multiple regression analysis showed that abnormality of glucose metabolism was an independent determinant of plasma ghrelin levels (P = 0.023). (2) There was no difference in frequency of Leu72Met polymorphisms between obese and control groups (36.09 vs. 41.00%). CONCLUSION Ghrelin is associated with obesity in childhood, especially associated with the glucose homeostasis. Lower ghrelin levels might be a result of obesity, but not a cause of obesity. The Leu72Met polymorphism of ghrelin gene is not associated with obesity and metabolic syndrome in Chinese children.
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Kos K, Harte AL, O'Hare PJ, Kumar S, McTernan PG. Ghrelin and the differential regulation of des-acyl (DSG) and oct-anoyl ghrelin (OTG) in human adipose tissue (AT). Clin Endocrinol (Oxf) 2009; 70:383-9. [PMID: 18616714 DOI: 10.1111/j.1365-2265.2008.03321.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVES Ghrelin, an important central acting orexigenic hormone, is predominantly secreted in the gastrointestinal tract. However little is known about the action of ghrelin in human adipose tissue (AT). AIM To study the expression of ghrelin in AT, the effects of octanoyl-(OTG) and des-acyl (DSG) ghrelin on lipolysis and lipogenesis, leptin release and potential peripheral signalling through the Y1 receptor. METHODS Ex vivo human AT was obtained from women undergoing elective surgery (46 (mean +/- SD) 6.8 years, body mass index (BMI): 25.6 +/- 5.0 kg/m(2), n = 20). Abdominal-subcutaneous (AbdSc) adipocytes were isolated and treated with recombinant human (rh) OTG and DSG to assess lipid metabolism leptin release and the influence of Y1-receptor blocker. RESULTS Ghrelin was expressed in AbdScAT and negatively correlated with BMI (lean: 3.6 +/- 0.74 optical-density-units (OD), obese: 1.64 +/- 0.45 OD, *P < 0.05). Only DSG significantly suppressed glycerol release (Control (C): 286 +/- 58 microl/l; DSG 1 nm: 224 +/- 38 microl/l downward arrow*; DSG 100 nm: 172 +/- 13 microl/l downward arrow*,* downward arrow P < 0.05, n = 7) and reduced hormone sensitive lipase expression (C: 1.0 +/- 0.3 OD; DSG 1 nm: 0.8 +/- 0.3 OD downward arrow*; DSG 100 nm: 0.6 +/- 0.1 OD downward arrow*, n = 4). However, both isoforms increased lipoprotein lipase expression (C: 1.0 +/- 0.3OD; DSG 100 nm: 0.2 +/- 0.4 OD upward arrow*; OTG 100 nm: 2.5 +/- 0.3 OD upward arrow*, n = 4), whilst blockade of Y1 eliminated this effect in both. Leptin was down-regulated by DSG only (DSG 1 nm: 5.3 +/- 0.7 ng/ml; DSG 100 nm: 4.1 +/- 0.7 ng/ml*) and was significant after BMI adjustment (P = 0.029). CONCLUSION Ghrelin was expressed in human AbdSc AT. In vitro, both OGT and DSG appear to mediate fat deposition with the lipogenic effects in part mediated by the Y1 receptor, whilst the influence of DSG affected lipolysis, lipogenesis and leptin secretion. Taken together, these studies support a local action for ghrelin isoforms on lipid and adipokine metabolism that further supports a cross talk between organs.
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Affiliation(s)
- K Kos
- Unit for Diabetes and Metabolism, Clinical Sciences Research Institute (CSRI), Warwick Medical School, Coventry, CV2 2DX West Midlands, UK
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Zou CC, Liang L, Wang CL, Fu JF, Zhao ZY. The change in ghrelin and obestatin levels in obese children after weight reduction. Acta Paediatr 2009; 98:159-65. [PMID: 18710433 DOI: 10.1111/j.1651-2227.2008.00997.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
AIM To investigate the role of ghrelin and obestatin in obesity mechanisms. METHODS A total of 88 obese children and 25 normal children were enrolled. Moreover, 46 obese children took part in a summer camp for weight reduction. Fasting ghrelin, obestatin and other biochemical parameters were measured in all subjects and re-measured in 45 obese children finishing the camp. RESULTS The ghrelin levels in the control and obese groups were 67.26 +/- 23.41 pmol/L and 56.53 +/- 15.97 pmol/L with a significant difference (p = 0.039), while the obestatin levels (89.41 +/- 23.63 vs. 83.13 +/- 17.21 pmol/L) were not significantly different (p = 0.083). The ghrelin/obestatin ratio in the controls was significantly higher than that in the obese group (p = 0.014). In the latter, fasting insulin and alanine aminotransferase were independent factors for ghrelin; fasting insulin, weight and gender were independent factors for obestatin and alanine aminotransferase was an independent factor for ghrelin/obestatin. Moreover, ghrelin, obestatin and ghrelin/obestatin increased after weight reduction (p < 0.05, respectively), and the increment in ghrelin and obestatin was associated with a decrement in insulin resistance. CONCLUSION These data suggest that ghrelin, obestatin and/or the ghrelin/obestatin ratio are associated with obesity in childhood.
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Affiliation(s)
- Chao Chun Zou
- Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine, 57 Zhugan Xiang, Hangzhou, China.
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Zou CC, Liang L, Zhao ZY. Factors associated with fasting plasma ghrelin levels in children and adolescents. World J Gastroenterol 2008; 14:790-4. [PMID: 18205273 PMCID: PMC2684010 DOI: 10.3748/wjg.14.790] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To measure plasma ghrelin levels in children and adolescents, analyze the associated factors, and investigate the role of ghrelin in obesity, insulin resistance and reproductive physiology.
METHODS: A total of 283 subjects aged 4.8-15.8 year were enrolled. Fasting blood samples were collected and plasma ghrelin levels were measured by radioimmunoassay. Fasting glucose (FG), fasting insulin (FI), baseline testosterone (T), estradiol (E2), prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), serum total cholesterol (TC), triglyceride (TG), alanine aminotransferase (ALT) and uric acid (UA) were measured. Body mass index (BMI), insulin resistance by homeostasis model (HOMA-IR) and beta cell function by homeostasis model (HOMA-β) were calculated.
RESULTS: The median ghrelin level was 290 ng/L (15.0-1325.0 ng/L). Bivariate correlation analysis showed that ghrelin levels were inversely correlated with BMI, ALT, TG, UA, LH, FI and HOMA-IR (all P < 0.05). No other significant correlation was found between ghrelin levels and age, gender, TC, E2, FSH, PRL, FG and HOMA-β. Stepwise multiple regression analysis showed that only BMI and FI were independent determinants of plasma ghrelin levels in these children and adolescents (P = 0.018 and P = 0.046, respectively), which explained 25.4% of the variance.
CONCLUSION: These data suggest that the lower ghrelin levels in obese subjects may be the result of obesity and hyperinsulinemia, which is very common in obese subjects. Moreover, ghrelin may regulate human reproductive physiology indirectly.
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Wurst FM, Graf I, Ehrenthal HD, Klein S, Backhaus J, Blank S, Graf M, Pridzun L, Wiesbeck GA, Junghanns K. Gender Differences for Ghrelin Levels in Alcohol-Dependent Patients and Differences Between Alcoholics and Healthy Controls. Alcohol Clin Exp Res 2007; 31:2006-11. [DOI: 10.1111/j.1530-0277.2007.00527.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Barazzoni R, Zanetti M, Cattin MR, Visintin L, Vinci P, Cattin L, Stebel M, Guarnieri G. Ghrelin enhances in vivo skeletal muscle but not liver AKT signaling in rats. Obesity (Silver Spring) 2007; 15:2614-23. [PMID: 18070752 DOI: 10.1038/oby.2007.313] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Ghrelin administration can induce fat weight gain and hyperglycemia (potentially through ghrelin-induced hepatic glucose production), but plasma ghrelin is positively associated with whole-body insulin sensitivity (mainly reflecting muscle insulin action) being increased in lean individuals or after diet-induced weight loss and reduced in obesity or after diet-induced weight gain. To investigate potential mechanisms, we measured in vivo effects of sustained ghrelin administration at a non-orexigenic dose on skeletal muscle and liver insulin signaling at the AKT level and adipokine expression changes. RESEARCH METHODS AND PROCEDURES Young-adult male rats received 4-day, twice daily subcutaneous ghrelin (200 mug/injection) or saline. We measured skeletal muscle (mixed, gastrocnemius; oxidative, soleus) and liver protein levels of activated [phosphorylated (P)] and total (T) AKT and glycogen synthase kinase (GSK; reflecting AKT-dependent GSK inactivation) and epididymal adipose tissue adipokine mRNA. RESULTS Ghrelin increased body weight (+1.4%) and blood glucose (both p < 0.05 vs. saline) but not food intake, plasma insulin, or free fatty acids. Ghrelin, however, enhanced P/T/AKT and P/T/GSK ratios and glucose transporter-4 mRNA in soleus (p < 0.05), but not in gastrocnemius, muscle. In contrast, ghrelin reduced hepatic P/T-AKT and P/T-GSK. No alterations occurred in adiponectin, leptin, or resistin transcripts or plasma adiponectin. DISCUSSION Despite moderate weight gain and in the absence of insulin-free fatty acid changes, sustained ghrelin administration enhanced oxidative muscle AKT activation. Reduced liver AKT signaling could potentially contribute to concomitant blood glucose increments. These findings support ghrelin as a novel tissue-specific modulator of lean tissue AKT signaling with insulin-sensitizing effects in skeletal muscle but not in liver in vivo.
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Affiliation(s)
- Rocco Barazzoni
- Clinica Medica, Dipartimento di Scienze Cliniche, Morfologiche, e Tecnologiche, University of Trieste, Trieste, Italy.
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Obesity in neurobiology. Prog Neurobiol 2007; 84:85-103. [PMID: 18006138 DOI: 10.1016/j.pneurobio.2007.09.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 06/21/2007] [Accepted: 09/23/2007] [Indexed: 01/25/2023]
Abstract
Obesity reflects an imbalance between energy uptake and expenditure that is mediated by behavior. Obesity is a growing epidemic and a major risk factor for neurobiological diseases like stroke, dementia, intracranial hypertension and sleep disorders. Conversely, obesity can also be induced by neurobiological disorders and drugs. The etiology of obesity is complex and includes biology, behavior and environment. Physicians are faced with the need to manage obesity while strategies for prevention and sustained weight reduction are limited. Present treatment options comprise lifestyle modification, diet, pharmacotherapy and bariatric surgery. Considerable headway has been made into elucidating the neurobiological underpinnings of obesogenic behavior. There is now a growing understanding of the metabolic, hormonal and behavioral circuitries that contribute to the complex and redundant system for energy balance. Changing the net balance of this system to prevent or reduce obesity requires multimodal and long-term interventions.
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Aydin S, Ozercan IH, Geckil H, Dagli F, Aydin S, Kumru S, Kilic N, Sahin I, Ozercan MR. Ghrelin is Present in Teeth. BMB Rep 2007; 40:368-72. [PMID: 17562288 DOI: 10.5483/bmbrep.2007.40.3.368] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ghrelin belongs to the family of a gut-brain hormone that promotes food intake and controls energy balance. Recently, it has also been shown to regulate bone formation directly. Dental tissue shares several functional, developmental and anatomical similarities with bone, and in the present study we have investigated the presence of ghrelin in 44 human teeth using immunocytochemistry and radioimmunoassay. Both methods showed that the hormone is present in canines and molars, mainly in the odontoblasts but also in the pulp. Ghrelin could potentially play interesting physiological roles in teeth.
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Affiliation(s)
- Suleyman Aydin
- Department of Biochemistry and Clinical Biochemistry, Firat University, Medical School (Firat Medical Center), 23119 Elazig, Turkey.
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Abstract
Ghrelin is produced primarily in the stomach in response to hunger, and circulates in the blood. Plasma ghrelin levels increase during fasting and decrease after ingesting glucose and lipid, but not protein. The efferent vagus nerve contributes to the fasting-induced increase in ghrelin secretion. Ghrelin secreted by the stomach stimulates the afferent vagus nerve and promotes food intake. Ghrelin also stimulates pituitary gland secretion of growth hormone (GH) via the afferent vagus nerve. GH inhibits stomach ghrelin secretion. These findings indicate that the vagal circuit between the central nervous system and stomach has a crucial role in regulating plasma ghrelin levels. Moreover, body mass index modulates plasma ghrelin levels. In a lean state and anorexia nervosa, plasma ghrelin levels are increased, whereas in obesity, except in Prader-Willi syndrome, plasma ghrelin levels are decreased and the feeding- and sleeping-induced decline in plasma ghrelin levels is disrupted. There are two forms of ghrelin: active n-octanoyl-modified ghrelin and des-acyl ghrelin. Fasting increases both ghrelin types compared with the fed state. Hyperphagia and obesity are likely to decrease plasma des-acyl ghrelin, but not n-octanoyl-modified ghrelin levels. Hypothalamic serum and glucocorticoid-inducible kinase-1 and serotonin 5-HT2C/1B receptor gene expression levels are likely to be proportional to plasma des-acyl ghrelin levels during fasting, whereas they are likely to be inversely proportional to plasma des-acyl ghrelin levels in an increased energy storage state such as obesity. Thus, a dysfunction of the ghrelin feedback systems might contribute to the pathophysiology of obesity and eating disorders.
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Affiliation(s)
- Katsunori Nonogaki
- Center of Excellence, Division of Molecular Metabolism and Diabetes, Tohoku University Graduate School of Medicine, Miyagi, Japan
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Couce ME, Cottam D, Esplen J, Teijeiro R, Schauer P, Burguera B. Potential role of hypothalamic ghrelin in the pathogenesis of human obesity. J Endocrinol Invest 2006; 29:599-605. [PMID: 16957407 DOI: 10.1007/bf03344158] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Ghrelin is a potent appetite stimulator, mainly synthesized in the stomach but also made in the brain. Paradoxically, obese subjects have lower plasma ghrelin than lean subjects and increase their weight in spite of low ghrelin levels. We hypothesize that central, and not peripheral ghrelin, is primarily responsible for overeating in humans. The aim of this study was to determine hypothalamic ghrelin levels in lean vs obese subjects. We collected anterior hypothalamus from lean and obese patients at the time of autopsy, and Western blots and semiquantitative RT-PCR for ghrelin and neuropeptide Y (NPY) were carried out. Our results showed that ghrelin expression was significantly higher in the hypothalamus of obese subjects compared to lean ones. This finding correlates with similar increases in NPY in the obese group. Ghrelin and NPY mRNA levels followed the same trend and were significantly higher in the hypothalamus in obese compared to lean subjects, suggesting a central origin for the increased protein content in the obese subjects. In conclusion, obesity in humans is associated with elevated central ghrelin. This data questions the significance of the role of peripheral ghrelin in the regulation of appetite in humans and suggests an important role for central ghrelin in the pathogenesis of obesity in humans.
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Affiliation(s)
- M E Couce
- Division of Neuropathology, University of Pittsburgh School of Medicine, Pittsburgh, USA.
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Tritos NA, Kokkotou EG. The physiology and potential clinical applications of ghrelin, a novel peptide hormone. Mayo Clin Proc 2006; 81:653-60. [PMID: 16706263 DOI: 10.4065/81.5.653] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Ghrelin, a peptide hormone originally identified as the endogenous ligand of the growth hormone secretagogue receptor, is secreted primarily from the stomach and secondarily from the small intestine and colon. Ghrelin may also be expressed in the pancreatic islets, hypothalamus, pituitary, and several tissues in the periphery. The growth hormone secretagogue receptor is widely expressed, suggesting diverse physiologic roles for ghrelin. A growing body of evidence suggests that, in addition to its predictable effect on growth hormone secretion, ghrelin has an important role in the short-term regulation of appetite and the long-term regulation of energy balance and glucose homeostasis. Recent studies have implicated ghrelin in the regulation of gastrointestinal, cardiovascular, and immune function and have suggested a role for ghrelin in bone physiology. The identification of obestatin, a novel peptide hormone derived from the same gene as ghrelin, has recently added further complexity to ghrelin physiology. Obestatin appears to have actions opposite of ghrelin on energy homeostasis and gastrointestinal function. Despite the rapid progress, many questions remain unanswered, including the regulation of ghrelin and obestatin secretion, the downstream pathways that mediate their effects, and their precise physiologic endocrine and paracrine roles. This review presents data on ghrelin structure, expression, and function, with emphasis placed on human studies, highlighting areas that require future investigation and providing speculation about potential clinical applications of ghrelin agonists or antagonists.
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Affiliation(s)
- Nicholas A Tritos
- Department of Endocrinology, Lahey Clinic Medical Center, Burlington, MA 01805, USA.
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Orr J, Davy B. Dietary Influences on Peripheral Hormones Regulating Energy Intake: Potential Applications for Weight Management. ACTA ACUST UNITED AC 2005; 105:1115-24. [PMID: 15983531 DOI: 10.1016/j.jada.2005.04.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The significant burden of overweight and obesity on our society necessitates the development of lifestyle strategies that facilitate successful long-term body weight management. Recently, the discovery of novel cellular modulators of the brain-gut axis have generated much interest in possible therapeutic manipulation of these and other hormones that regulate energy intake. These modulators include the enterohormones ghrelin, peptide YY 3-36, and cholecystokinin, and the adipocyte-derived hormone leptin. There is some evidence that dietary macronutrient composition can influence concentrations of these hormones, which could impact sensations of hunger, satiety, and ultimately energy intake. The purpose of this review is to provide background information on these four peripheral hormones involved in energy intake regulation, to discuss what is currently known about their mechanism of action, and to present research findings related to the effect of macronutrient composition on concentrations and efficacy of these hormones. Potential applications of this information are also discussed.
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Affiliation(s)
- Jeb Orr
- Department of Human Nutrition, Foods and Exercise, Virginia Tech, Blacksburg 24061, USA
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Kim MS, Namkoong C, Kim HS, Jang PG, Kim Pak YM, Katakami H, Park JY, Lee KU. Chronic central administration of ghrelin reverses the effects of leptin. Int J Obes (Lond) 2004; 28:1264-71. [PMID: 15278100 DOI: 10.1038/sj.ijo.0802647] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To determine whether chronic central administration of ghrelin can block the effects of leptin on food intake, adiposity, and plasma concentrations of metabolic parameters and hormones. DESIGN Intracerebroventricular (ICV) infusions of leptin (5 microg/day) for 7 days, with or without ghrelin (1.2 microg/day), in rats. Rats administered leptin plus ghrelin were divided into ad lib-fed and food-restricted groups. MEASUREMENT Body weight and food intake were monitored daily. Following killing on day 8, epididymal fat weight and fasting plasma concentrations of glucose, insulin, leptin, ghrelin, IGF-1, and adiponectin were determined. RESULTS ICV infusion of leptin decreased food intake by 39% and fat weight by 41%. Leptin decreased plasma concentrations of glucose, insulin, and leptin and increased plasma ghrelin levels. Central coadministration of ghrelin blocked the effects of leptin. Most of the effects of ghrelin were diminished by food restriction but ghrelin effect on adiposity and plasma insulin concentrations remained in food-restricted rats. CONCLUSION Chronic central administration of ghrelin reversed the effects of leptin, primarily by altering food intake, but ghrelin may have regulatory effects on adiposity and plasma insulin levels independent of feeding effect.
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Affiliation(s)
- M-S Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Ulsan College of Medicine, Seoul 138-736, Korea
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van der Lely AJ, Tschöp M, Heiman ML, Ghigo E. Biological, physiological, pathophysiological, and pharmacological aspects of ghrelin. Endocr Rev 2004; 25:426-57. [PMID: 15180951 DOI: 10.1210/er.2002-0029] [Citation(s) in RCA: 802] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ghrelin is a peptide predominantly produced by the stomach. Ghrelin displays strong GH-releasing activity. This activity is mediated by the activation of the so-called GH secretagogue receptor type 1a. This receptor had been shown to be specific for a family of synthetic, peptidyl and nonpeptidyl GH secretagogues. Apart from a potent GH-releasing action, ghrelin has other activities including stimulation of lactotroph and corticotroph function, influence on the pituitary gonadal axis, stimulation of appetite, control of energy balance, influence on sleep and behavior, control of gastric motility and acid secretion, and influence on pancreatic exocrine and endocrine function as well as on glucose metabolism. Cardiovascular actions and modulation of proliferation of neoplastic cells, as well as of the immune system, are other actions of ghrelin. Therefore, we consider ghrelin a gastrointestinal peptide contributing to the regulation of diverse functions of the gut-brain axis. So, there is indeed a possibility that ghrelin analogs, acting as either agonists or antagonists, might have clinical impact.
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Affiliation(s)
- Aart J van der Lely
- Department of Internal Medicine, Erasmus Medical Center, 3015 GD Rotterdam, The Netherlands.
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