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Fan BW, Liu YL, Zhu GX, Wu B, Zhang MM, Deng Q, Wang JL, Chen JX, Han RW, Wei J. The active fragments of ghrelin cross the blood-brain barrier and enter the brain to produce antinociceptive effects after systemic administration. Can J Physiol Pharmacol 2021; 99:1057-1068. [PMID: 34492212 DOI: 10.1139/cjpp-2020-0668] [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] [Indexed: 11/22/2022]
Abstract
G (1-5)-NH2, G (1-7)-NH2, and G (1-9) are the active fragments of ghrelin. The aim of this study was to investigate the antinociceptive effects, their ability to cross the blood-brain barrier, and the receptor mechanism(s) of these fragments using the tail withdrawal test in male Kunming mice. The antinociceptive effects of these fragments (2, 6, 20, and 60 nmol/mouse) were tested at 5, 10, 20, 30, 40, 50, and 60 min after intravenous (i.v.) injection. These fragments induced dose- and time-related antinociceptive effects relative to saline. Using the near infrared fluorescence imaging experiments, our results showed that these fragments could cross the brain-blood barrier and enter the brain. The antinociceptive effects of these fragments were completely antagonized by naloxone (intracerebroventricular, i.c.v.); however, naloxone methiodide (intraperitoneal, i.p.), which is the peripheral restricted opioid receptor antagonist, did not antagonize these antinociceptive effects. Furthermore, the GHS-R1α antagonist [D-Lys3]-GHRP-6 (i.c.v.) completely antagonized these antinociceptive effects, too. These results suggested that these fragments induced antinociceptive effects through central opioid receptors and GHS-R1α. In conclusion, our studies indicated that these active fragments of ghrelin could cross the brain-blood barrier and enter the brain and induce antinociceptive effects through central opioid receptors and GHS-R1α after intravenous injection.
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Affiliation(s)
- Bao-Wei Fan
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Yong-Ling Liu
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Gui-Xian Zhu
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Bing Wu
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Min-Min Zhang
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Qing Deng
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Jing-Lei Wang
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Jia-Xiang Chen
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Ren-Wen Han
- Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, China
| | - Jie Wei
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
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Gortan Cappellari G, Barazzoni R. Ghrelin forms in the modulation of energy balance and metabolism. Eat Weight Disord 2019; 24:997-1013. [PMID: 30353455 DOI: 10.1007/s40519-018-0599-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/16/2018] [Indexed: 02/06/2023] Open
Abstract
Ghrelin is a gastric hormone circulating in acylated (AG) and unacylated (UnAG) forms. This narrative review aims at presenting current emerging knowledge on the impact of ghrelin forms on energy balance and metabolism. AG represents ~ 10% of total plasma ghrelin, has an appetite-stimulating effect and is the only form for which a receptor has been identified. Moreover, other metabolic AG-induced effects have been reported, including the modulation of glucose homeostasis with stimulation of liver gluconeogenesis, the increase of fat mass and the improvement of skeletal muscle mitochondrial function. On the other hand, UnAG has no orexigenic effects, however recent reports have shown that it is directly involved in the modulation of skeletal muscle energy metabolism by improving a cluster of interlinked functions including mitochondrial redox activities, tissue inflammation and insulin signalling and action. These findings are in agreement with human studies which show that UnAG circulating levels are positively associated with insulin sensitivity both in metabolic syndrome patients and in a large cohort from the general population. Moreover, ghrelin acylation is regulated by a nutrient sensor mechanism, specifically set on fatty acids availability. These recent findings consistently point towards a novel independent role of UnAG as a regulator of muscle metabolic pathways maintaining energy status and tissue anabolism. While a specific receptor for UnAG still needs to be identified, recent evidence strongly supports the hypothesis that the modulation of ghrelin-related molecular pathways, including those involved in its acylation, may be a potential novel target in the treatment of metabolic derangements in disease states characterized by metabolic and nutritional complications.Level of evidence Level V, narrative review.
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Affiliation(s)
- Gianluca Gortan Cappellari
- Department of Medical, Surgical and Health Sciences, University of Trieste, Strada di Fiume, 447, 34149, Trieste, Italy.
| | - Rocco Barazzoni
- Department of Medical, Surgical and Health Sciences, University of Trieste, Strada di Fiume, 447, 34149, Trieste, Italy.
- Azienda Sanitaria Universitaria Integrata di Trieste (ASUITS), Trieste, Italy.
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3
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Wu B, Liu Y, Liu F, Deng Q, Wang J, Han R, Zhang D, Chen J, Wei J. The antinociceptive effects and molecular mechanisms of ghrelin(1–7)-NH2 at the supraspinal level in acute pain in mice. Brain Res Bull 2019; 146:112-123. [DOI: 10.1016/j.brainresbull.2018.12.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 12/07/2018] [Accepted: 12/26/2018] [Indexed: 01/01/2023]
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Liu FY, Zhang MM, Zeng P, Liu WW, Wang JL, Yang B, Dai Q, Wei J. Study on the molecular mechanism of antinociception induced by ghrelin in acute pain in mice. Peptides 2016; 83:1-7. [PMID: 27474249 DOI: 10.1016/j.peptides.2016.07.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 07/24/2016] [Accepted: 07/25/2016] [Indexed: 01/04/2023]
Abstract
Ghrelin has been identified as the endogenous ligand for the GHS-R1α (growth hormone secretagogue receptor 1 alpha). Our previous experiments have indicated that ghrelin (i.c.v.) induces antinociceptive effects in acute pain in mice, and the effects were mediated through the central opioid receptors and GHS-R1α. However, which opioid receptor (OR) mediates the antinociceptive effects and the molecular mechanisms are also needed to be further explored. In the present study, the antinociceptive effects of ghrelin (i.c.v.) could be fully antagonized by δ-opioid receptor antagonist NTI. Furthermore, the mRNA and protein levels of δ-opioid peptide PENK and δ-opioid receptor OPRD were increased after i.c.v injection of ghrelin. Thus, it showed that the antinociception of ghrelin was correlated with the GHS-R1α and δ-opioid receptors. To explore which receptor was firstly activated by ghrelin, GHS-R1α antagonist [D-Lys(3)]-GHRP-6 was co-injection (i.c.v.) with deltorphin II (selective δ-opioid receptor agonist). Finally, the antinociception induced by deltorphin II wasn't blocked by the co-injection (i.c.v.) of [D-Lys(3)]-GHRP-6, indicating that the GHS-R1α isn't on the backward position of δ-opioid receptor. The results suggested that i.c.v. injection of ghrelin initially activated the GHS-R1α, which in turn increased the release of endogenous PENK to activation of OPRD to produce antinociception.
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Affiliation(s)
- Fu-Yan Liu
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Min-Min Zhang
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Ping Zeng
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Wen-Wen Liu
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Jing-Lei Wang
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Bei Yang
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China
| | - Qun Dai
- Medical Experimental Teaching Department, Nanchang University, Nanchang 330031, China
| | - Jie Wei
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China.
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Nissley DA, O'Brien EP. Altered Co-Translational Processing Plays a Role in Huntington's Pathogenesis-A Hypothesis. Front Mol Neurosci 2016; 9:54. [PMID: 27458341 PMCID: PMC4933702 DOI: 10.3389/fnmol.2016.00054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 06/22/2016] [Indexed: 11/13/2022] Open
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by the expansion of a CAG codon repeat region in the HTT gene's first exon that results in huntingtin protein aggregation and neuronal cell death. The development of therapeutic treatments for HD is hindered by the fact that while the etiology and symptoms of HD are understood, the molecular processes connecting this genotype to its phenotype remain unclear. Here, we propose the novel hypothesis that the perturbation of a co-translational process affects mutant huntingtin due to altered translation-elongation kinetics. These altered kinetics arise from the shift of a proline-induced translational pause site away from Htt's localization sequence due to the expansion of the CAG-repeat segment between the poly-proline and localization sequences. Motivation for this hypothesis comes from recent experiments in the field of protein biogenesis that illustrate the critical role that temporal coordination of co-translational processes plays in determining the function, localization, and fate of proteins in cells. We show that our hypothesis is consistent with various experimental observations concerning HD pathology, including the dependence of the age of symptom onset on CAG repeat number. Finally, we suggest three experiments to test our hypothesis.
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Affiliation(s)
- Daniel A Nissley
- O'Brien Lab, Department of Chemistry, The Pennsylvania State University University Park, PA, USA
| | - Edward P O'Brien
- O'Brien Lab, Department of Chemistry, The Pennsylvania State University University Park, PA, USA
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Integrating solid-state NMR and computational modeling to investigate the structure and dynamics of membrane-associated ghrelin. PLoS One 2015; 10:e0122444. [PMID: 25803439 PMCID: PMC4372444 DOI: 10.1371/journal.pone.0122444] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 02/11/2015] [Indexed: 12/18/2022] Open
Abstract
The peptide hormone ghrelin activates the growth hormone secretagogue receptor 1a, also known as the ghrelin receptor. This 28-residue peptide is acylated at Ser3 and is the only peptide hormone in the human body that is lipid-modified by an octanoyl group. Little is known about the structure and dynamics of membrane-associated ghrelin. We carried out solid-state NMR studies of ghrelin in lipid vesicles, followed by computational modeling of the peptide using Rosetta. Isotropic chemical shift data of isotopically labeled ghrelin provide information about the peptide’s secondary structure. Spin diffusion experiments indicate that ghrelin binds to membranes via its lipidated Ser3. Further, Phe4, as well as electrostatics involving the peptide’s positively charged residues and lipid polar headgroups, contribute to the binding energy. Other than the lipid anchor, ghrelin is highly flexible and mobile at the membrane surface. This observation is supported by our predicted model ensemble, which is in good agreement with experimentally determined chemical shifts. In the final ensemble of models, residues 8–17 form an α-helix, while residues 21–23 and 26–27 often adopt a polyproline II helical conformation. These helices appear to assist the peptide in forming an amphipathic conformation so that it can bind to the membrane.
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Zeng P, Li S, Zheng YH, Liu FY, Wang JL, Zhang DL, Wei J. Ghrelin receptor agonist, GHRP-2, produces antinociceptive effects at the supraspinal level via the opioid receptor in mice. Peptides 2014; 55:103-9. [PMID: 24607724 DOI: 10.1016/j.peptides.2014.02.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 02/20/2014] [Accepted: 02/20/2014] [Indexed: 02/04/2023]
Abstract
GHRP-2 is a synthetic agonist of ghrelin receptor. GHRP-2 has similar physiological functions with ghrelin. In our previous study, ghrelin (i.c.v.) could induce analgesic effect through an interaction with GHS-R1α and with the central opioid system in the acute pain in mice. To date, the function of GHRP-2 in pain processing was not understood. Therefore the aim of this study was to investigate the effects of GHRP-2 on pain modulation at supraspinal level in mice using the tail immersion test. Intracerebroventricular (i.c.v.) administration of GHRP-2 (0.1, 0.3, 1, 3 and 10 nmol/L) produced a concentration- and time-related antinociceptive effect. This effect could be fully antagonized by GHS-R1α antagonist [d-Lys(3)]-GHRP-6, indicating that the analgesic effect induced by GHRP-2 is mediated through the activation of GHS-R1α. Interestingly, naloxone, naltrindole and nor-binaltorphimine, but not β-funaltrexamine, could also block the analgesic effect markedly, suggesting that δ- and κ-opioid receptor is involved in the analgesic response evoked by GHRP-2. Moreover, i.c.v. administration of GHRP-2 potentiated the analgesic effect induced by morphine (i.c.v., 1 nmol/L) and this potentiated effect could not be reversed by [d-Lys(3)]-GHRP-6. Thus these findings may be a new strategy on investigating the interaction between ghrelin system and opioids on pain modulation. Furthermore, GHRP-2 may be a promising peptide for developing new analgesic drugs.
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Affiliation(s)
- Ping Zeng
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi 330006, China
| | - Shu Li
- Key Laboratory of Poyang Lake Environmental and Resource Utilization, Ministry of Education, School of Environmental and Chemical Engineering, Nanchang University, Nanchang, Jiangxi 330029, China
| | - Yue-hui Zheng
- Medical Experimental Teaching Department, Nanchang University, Nanchang 330031, China
| | - Fu-Yan Liu
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi 330006, China
| | - Jing-lei Wang
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi 330006, China
| | - Da-lei Zhang
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi 330006, China
| | - Jie Wei
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi 330006, China.
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8
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Zeng P, Chen JX, Yang B, Zhi X, Guo FX, Sun ML, Wang JL, Wei J. Attenuation of systemic morphine-induced analgesia by central administration of ghrelin and related peptides in mice. Peptides 2013; 50:42-9. [PMID: 24113541 DOI: 10.1016/j.peptides.2013.09.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/27/2013] [Accepted: 09/27/2013] [Indexed: 12/28/2022]
Abstract
Ghrelin, an acylated 28-amino peptide secreted in the gastric endocrine cells, has been demonstrated to stimulate the release of growth hormone, increase food intake, and inhibit pro-inflammatory cascade, etc. Ghrelin mainly combines with its receptor (GHS-R1α) to play the role in physiological and pathological functions. It has been reported that ghrelin plays important roles in the control of pain through interaction with the opioid system in inflammatory pain and acute pain. However, very few studies show the effect of supraspinal ghrelin system on antinociception induced by intraperitoneal (i.p.) administration of morphine. In the present study, intracerebroventricular (i.c.v.) injection of ghrelin (0.1, 1, 10 and 100 nmol/L) produced inhibition of systemic morphine (6 mg/kg, i.p.) analgesia in the tail withdrawal test. Similarly, i.c.v. injection GHRP-6 and GHRP-2 which are the agonists of GHS-R1α, also decreased analgesia effect induced by morphine injected intraperitoneally in mice. Furthermore, these anti-opioid activities of ghrelin and related peptides were not blocked by pretreatment with the GHS-R1α selective antagonist [d-Lys(3)]-GHRP-6 (100 nmol/L, i.c.v.). These results demonstrated that central ghrelin and related peptides could inhibit the analgesia effect induced by intraperitoneal (i.p.) administration of morphine. The anti-opioid effects of ghrelin and related peptides do not interact with GHS-R1a. These findings may pave the way for a new strategy on investigating the interaction between ghrelin system and opioids on pain modulation.
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Affiliation(s)
- Ping Zeng
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi 330006, China
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9
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Delporte C. Structure and physiological actions of ghrelin. SCIENTIFICA 2013; 2013:518909. [PMID: 24381790 PMCID: PMC3863518 DOI: 10.1155/2013/518909] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 11/10/2013] [Indexed: 05/30/2023]
Abstract
Ghrelin is a gastric peptide hormone, discovered as being the endogenous ligand of growth hormone secretagogue receptor. Ghrelin is a 28 amino acid peptide presenting a unique n-octanoylation modification on its serine in position 3, catalyzed by ghrelin O-acyl transferase. Ghrelin is mainly produced by a subset of stomach cells and also by the hypothalamus, the pituitary, and other tissues. Transcriptional, translational, and posttranslational processes generate ghrelin and ghrelin-related peptides. Homo- and heterodimers of growth hormone secretagogue receptor, and as yet unidentified receptors, are assumed to mediate the biological effects of acyl ghrelin and desacyl ghrelin, respectively. Ghrelin exerts wide physiological actions throughout the body, including growth hormone secretion, appetite and food intake, gastric secretion and gastrointestinal motility, glucose homeostasis, cardiovascular functions, anti-inflammatory functions, reproductive functions, and bone formation. This review focuses on presenting the current understanding of ghrelin and growth hormone secretagogue receptor biology, as well as the main physiological effects of ghrelin.
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Affiliation(s)
- Christine Delporte
- Laboratory of Pathophysiological and Nutritional Biochemistry, Université Libre de Bruxelles, 808 Route de Lennik, Bat G/E-CP611, 1070 Brussels, Belgium
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10
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De Ricco R, Valensin D, Gaggelli E, Valensin G. Conformation propensities of des-acyl-ghrelin as probed by CD and NMR. Peptides 2013; 43:62-7. [PMID: 23470254 DOI: 10.1016/j.peptides.2013.02.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 02/20/2013] [Accepted: 02/20/2013] [Indexed: 12/30/2022]
Abstract
Des-acyl-ghrelin is a 28 amino acid peptide secreted by both human and rat stomach. Together with ghrelin and obestatin, it is obtained by post-translational modification of a 117 aminoacid prepropeptide mainly expressed in distinct endocrine cell type in the stomach. Although its receptor has not been unambiguously identified so far, des-acyl-ghrelin is considered one of the strongest antagonists of ghrelin in activating the growth hormone secretagogue receptor (GHS-R). Here the secondary structure of des-acyl-ghrelin in different experimental conditions has been investigated and compared with that of obestatin, a bioactive peptide having similar biological functions. CD and NMR techniques have been combined for gaining the desired conformational features. The obtained structures support a steady alpha-helix structure spanning residues from 7 to 14, very similar to that observed for obestatin at the same experimental conditions, leading to suggest that a similar secondary structure can be associated with the similar biological role.
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Affiliation(s)
- Riccardo De Ricco
- Department of Biotechnology, University of Siena, Via A. Moro 2, 53100 Siena, Italy
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11
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Wei J, Zhi X, Wang XL, Zeng P, Zou T, Yang B, Wang JL. In vivo characterization of the effects of ghrelin on the modulation of acute pain at the supraspinal level in mice. Peptides 2013; 43:76-82. [PMID: 23500519 DOI: 10.1016/j.peptides.2013.03.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 03/04/2013] [Accepted: 03/04/2013] [Indexed: 12/12/2022]
Abstract
Ghrelin, an acylated peptide produced in the stomach, increases food intake and growth hormone secretion, inhibits pro-inflammatory cascade, etc. Ghrelin and its receptor (GHS-R1a) mRNA were found in the area related to the regions for controlling pain transmission, such as the hypothalamus, the midbrain, the spinal cord, etc. Ghrelin has been shown to have antinociceptive activity and also anti-inflammatory properties in inflammatory pain and chronic neuropathic pain. Therefore, the aim of the present study was to investigate the effects of ghrelin for the first time in the acute pain modulation at the supraspinal level, using the tail withdrawal test and hot-plate test in mice. Intracerebroventricular (i.c.v.) administration of ghrelin (mouse, 0.1-3 nmol) produced a dose- and time-related antinociceptive effect in the tail withdrawal test and hot-plate test, respectively. Antinociceptive effect elicited by ghrelin (i.c.v., 1 nmol) was significantly antagonized by opioid receptor antagonist naloxone (i.c.v., 10 nmol co-injection or i.p., 10mg/kg, 10 min prior to ghrelin) in both tail withdrawal test and hot-plate test. At these doses, naloxone significantly antagonized the antinociceptive effect induced by morphine (i.c.v., 3 nmol). Ghrelin (i.c.v., 1 nmol)-induced antinociception was significantly antagonized by co-injection with 10 nmol [d-Lys3]-GHRP-6, the selective antagonist of GHS-R1a identified more recently, while [d-Lys3]-GHRP-6 (10 nmol) alone induced neither hyperalgesia nor antinociception. Overall this data indicate that ghrelin could produce antinociception through an interaction with GHS-R1a and with the central opioid system. Thus ghrelin may be a promising peptide for developing new analgesic drugs.
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Affiliation(s)
- Jie Wei
- Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi 330006, China.
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12
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Min C, Ohta K, Kajiya M, Zhu T, Sharma K, Shin J, Mawardi H, Howait M, Hirschfeld J, Bahammam L, Ichimonji I, Ganta S, Amiji M, Kawai T. The antimicrobial activity of the appetite peptide hormone ghrelin. Peptides 2012; 36:151-6. [PMID: 22634233 PMCID: PMC3402649 DOI: 10.1016/j.peptides.2012.05.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 05/13/2012] [Accepted: 05/14/2012] [Indexed: 01/22/2023]
Abstract
The present study examined the antimicrobial activity of the peptide ghrelin. Both major forms of ghrelin, acylated ghrelin (AG) and desacylated ghrelin (DAG), demonstrated the same degree of bactericidal activity against Gram-negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa), while bactericidal effects against Gram-positive Staphylococcus aureus (S. aureus) and Enterococcus faecalis (E. faecalis) were minimal or absent, respectively. To elucidate the bactericidal mechanism of AG and DAG against bacteria, we monitored the effect of the cationic peptides on the zeta potential of E. coli. Our results show that AG and DAG similarly quenched the negative surface charge of E. coli, suggesting that ghrelin-mediated bactericidal effects are influenced by charge-dependent binding and not by acyl modification. Like most cationic antimicrobial peptides (CAMPs), we also found that the antibacterial activity of AG was attenuated in physiological NaCl concentration (150mM). Nonetheless, these findings indicate that both AG and DAG can act as CAMPs against Gram-negative bacteria.
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Affiliation(s)
- Christine Min
- Department of Immunology, Forsyth Institute, Cambridge, MA 02142, USA
| | - Kouji Ohta
- Department of Immunology, Forsyth Institute, Cambridge, MA 02142, USA
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Mikihito Kajiya
- Department of Immunology, Forsyth Institute, Cambridge, MA 02142, USA
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Tongbo Zhu
- Department of Immunology, Forsyth Institute, Cambridge, MA 02142, USA
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Kanika Sharma
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Jane Shin
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA
| | - Hani Mawardi
- Department of Immunology, Forsyth Institute, Cambridge, MA 02142, USA
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA
- Oral Medicine & Oral Diagnosis Division, Oral Basic & Clinical Sciences Department, King Abdul Aziz University, P.O. Box 80209, Jeddah 21589, Saudi Arabia
| | - Mohammed Howait
- Department of Immunology, Forsyth Institute, Cambridge, MA 02142, USA
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA
- Endodontics Division, Department of Conservative Dental Sciences, Faculty of Dentistry, King Abdul Aziz University, P.O. Box 80209, Jeddah 21589, Saudi Arabia
| | | | - Laila Bahammam
- Department of Immunology, Forsyth Institute, Cambridge, MA 02142, USA
- Endodontics Division, Department of Conservative Dental Sciences, Faculty of Dentistry, King Abdul Aziz University, P.O. Box 80209, Jeddah 21589, Saudi Arabia
| | - Isao Ichimonji
- Department of Immunology, Forsyth Institute, Cambridge, MA 02142, USA
| | - Srinivas Ganta
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Mansoor Amiji
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
| | - Toshihisa Kawai
- Department of Immunology, Forsyth Institute, Cambridge, MA 02142, USA
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA
- Corresponding author, Toshihisa Kawai, Department of Immunology, Forsyth Institute, Tel: +1-617-892-8317, Fax: +1-617-892-8437, , 245 First Street, Cambridge, MA 02142, USA
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Zizzari P, Hassouna R, Grouselle D, Epelbaum J, Tolle V. Physiological roles of preproghrelin-derived peptides in GH secretion and feeding. Peptides 2011; 32:2274-82. [PMID: 21530598 DOI: 10.1016/j.peptides.2011.04.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 04/04/2011] [Accepted: 04/07/2011] [Indexed: 12/26/2022]
Abstract
Among the factors playing a crucial role in the regulation of energy metabolism, gastro-intestinal peptides are essential signals to maintain energy homeostasis as they relay to the central nervous system the informations about the nutritional status of the body. Among these factors, preproghrelin is a unique prohormone as it encodes ghrelin, a powerful GH secretagogue and the only orexigenic signal from the gastrointestinal tract and obestatin, a proposed functional ghrelin antagonist. These preproghrelin-derived peptides may contribute to balance energy intake, metabolism and body composition by regulating the activity of the GH/IGF-1 axis and appetite. Whereas the contribution of ghrelin has been well characterized, the role of the more recently identified obestatin, in this regulatory process is still controversial. In this chapter, we describe the contribution of these different preproghrelin-derived peptides and their receptors in the regulation of GH secretion and feeding. Data obtained from pharmacological approaches, mutant models and evaluation of the hormones in animal and human models are discussed.
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Affiliation(s)
- Philippe Zizzari
- UMR894 INSERM, Centre de Psychiatrie et Neurosciences, Université Paris Descartes, 2 ter rue d'Alésia, 75014 Paris, France
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Huang Y, Li L, Washington JM, Xu X, Sando JJ, Lin D, Zuo Z. Inhibition of isoflurane-induced increase of cell-surface redistribution and activity of glutamate transporter type 3 by serine 465 sequence-specific peptides. Eur J Pharmacol 2011; 655:16-22. [PMID: 21266171 DOI: 10.1016/j.ejphar.2011.01.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 12/08/2010] [Accepted: 01/07/2011] [Indexed: 01/17/2023]
Abstract
Excitatory amino acid transporters (EAAT) transport glutamate into cells to regulate glutamate neurotransmission and to maintain nontoxic extracellular glutamate levels for neurons. We showed previously that the commonly used volatile anesthetic isoflurane increases the transporting activity of EAAT3, the major neuronal EAAT. This effect requires a protein kinase C (PKC) α-mediated and S465-dependent EAAT3 redistribution to the plasma membrane. Thus, we hypothesize that specific peptides can be designed to block this effect. We conjugated a 10-amino acid synthetic peptide with a sequence identical to that of EAAT3 around the S465 to a peptide that can facilitate permeation of the plasma membrane. This fusion peptide inhibited the isoflurane-increased EAAT3 activity and redistribution to the plasma membrane in C6 cells and hippocampus. It did not affect the basal EAAT3 activity. This peptide also attenuated isoflurane-induced increase of PKCα in the immunoprecipitates produced by an anti-EAAT3 antibody. A scrambled peptide that has the same amino acid composition as the S465 sequence-specific peptide but has a random sequence did not change the effects of isoflurane on EAAT3. The S465 sequence-specific peptide, but not the scrambled peptide, is a good PKCα substrate in in vitro assay. These peptides did not affect cell viability. These results, along with our previous findings, strongly suggest that PKCα interacts with EAAT3 to regulate its functions. The S465 sequence-specific peptide may interrupt this interaction and is an effective inhibitor for the regulation of EAAT3 activity and trafficking by PKCα and isoflurane.
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Affiliation(s)
- Yueming Huang
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA 22908, USA
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15
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Großauer J, Kosol S, Schrank E, Zangger K. The peptide hormone ghrelin binds to membrane-mimetics via its octanoyl chain and an adjacent phenylalanine. Bioorg Med Chem 2010; 18:5483-8. [PMID: 20621491 PMCID: PMC3038380 DOI: 10.1016/j.bmc.2010.06.062] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 06/15/2010] [Accepted: 06/16/2010] [Indexed: 02/01/2023]
Abstract
The peptide hormone ghrelin, which is the natural ligand of the membrane-bound growth hormone secretagogue receptor (GHS-R), regulates overall body and cell growth, energy homeostasis, carbohydrate, protein and lipid metabolism and water electrolyte balance. It contains an O-acyl linked octanoyl group on Ser3 and is the only peptide known to contain such a modification. Using solution state NMR spectroscopy and ultrafiltration we found that human ghrelin binds to membrane-mimetic environments via its octanoyl group as well as the aromatic moiety of Phe4. Relaxation enhancements in a paramagnetic environment reveal that both the octanoyl group on Ser3 and the aromatic group on Phe4 are inserted deep into the hydrophobic core of phosphocholine assemblies while the remaining peptide is freely mobile in solution. In contrast, no binding was observed for des-octanoyl ghrelin. Thus, the octanoyl chain, together with the Phe4 aromatic group of ghrelin, functions as a membrane anchor. Our results are in parallel with the previous finding that a bulky hydrophobic group on Ser3 and Phe4 of ghrelin are necessary for its function and thus indicate that membrane-binding is essential for ghrelin function.
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Affiliation(s)
| | | | | | - Klaus Zangger
- Institute of Chemistry/Organic and Bioorganic Chemistry, University of Graz, Graz, Austria
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16
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Staes E, Absil PA, Lins L, Brasseur R, Deleu M, Lecouturier N, Fievez V, Rieux AD, Mingeot-Leclercq MP, Raussens V, Préat V. Acylated and unacylated ghrelin binding to membranes and to ghrelin receptor: towards a better understanding of the underlying mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:2102-13. [PMID: 20637180 DOI: 10.1016/j.bbamem.2010.07.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 07/02/2010] [Accepted: 07/06/2010] [Indexed: 10/19/2022]
Abstract
The O-octanoylation of human ghrelin is a natural post-translational modification that enhances its binding to model membranes and could potentially play a central role in ghrelin biological activities. Here, we aimed to clarify the mechanisms that drive ghrelin to the membrane and hence to its receptor that mediates most of its endocrinological effects. As the acylation enhances ghrelin lipophilicity and that ghrelin contains many basic residues, we examined the electrostatic attraction and/or hydrophobic interactions with membranes. Using various liposomes and buffer conditions in binding, zeta potential and isothermal titration calorimetry studies, we found that whereas acylated and unacylated ghrelin were both electrostatically attracted towards the membrane, only acylated ghrelin penetrated into the headgroup and the lipid backbone regions of negatively charged membranes. The O-acylation induced a 120-fold increase in ghrelin local concentration in the membrane. However, acylated ghrelin did not deeply penetrate the membrane nor did it perturb its organisation. Conformational studies by circular dichroism and attenuated total reflection Fourier transformed infrared as well as in silico modelling revealed that both forms of ghrelin mainly adopted the same structure in aqueous, micellar and bilayer environments even though acylated ghrelin structure is slightly more α-helical in a lipid bilayer environment. Altogether our results suggest that membrane acts as a "catalyst" in acylated ghrelin binding to the ghrelin receptor and hence could explain why acylated and unacylated ghrelin are both full agonists of this receptor but in the nanomolar and micromolar range, respectively.
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Affiliation(s)
- Edith Staes
- Université catholique de Louvain, Unité de Pharmacie Galénique, 1200 Brussels, Belgium.
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Currie PJ, John CS, Nicholson ML, Chapman CD, Loera KE. Hypothalamic paraventricular 5-hydroxytryptamine inhibits the effects of ghrelin on eating and energy substrate utilization. Pharmacol Biochem Behav 2010; 97:152-5. [PMID: 20573591 DOI: 10.1016/j.pbb.2010.05.027] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 05/21/2010] [Accepted: 05/26/2010] [Indexed: 01/17/2023]
Abstract
Ghrelin microinjections into discrete regions of the hypothalamus, including the paraventricular nucleus (PVN), stimulate eating and promote carbohydrate oxidation, effects similar to PVN microinjection of neuropeptide Y (NPY). We have also reported that NPY's orexigenic and metabolic effects are antagonized by pretreatment with 5-hydroxytryptamine (5-HT) or 5-HT receptor agonists. In order to determine whether 5-HT also inhibits ghrelin's orexigenic and metabolic actions, the present study examined the effects of 5-HT pretreatment on ghrelin-induced alterations in eating and energy substrate utilization following direct injections into the hypothalamic PVN. Both 5-HT (5-20 nmol) and ghrelin (100 pmol) were administered at the onset of the dark cycle. Food intake was measured 2h postinjection. A separate group of rats (n=8) was injected with 5-HT paired with ghrelin and respiratory quotient (RQ; VCO(2)/VO(2)) was measured over 2h using an open circuit calorimeter. PVN injections of ghrelin increased food intake and increased RQ, reflecting a shift in energy substrate utilization in favor of carbohydrate oxidation. 5-HT effectively blocked the effects of ghrelin on both food intake and RQ. We then administered the 5-HT(2A/2C), receptor agonist, DOI, immediately prior to ghrelin. Similar to 5-HT, PVN DOI blocked ghrelin-induced eating and inhibited the peptide's effect on substrate utilization. These data are in agreement with other evidence suggesting that ghrelin functions as a gut-brain peptide in the control of food intake and energy metabolism, and indicate that 5-HT acts within the PVN to modulate ghrelin's orexigenic and metabolic signaling.
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Affiliation(s)
- Paul J Currie
- Department of Psychology, Reed College, Portland, OR 97202, USA.
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Interaction between ghrelin and the ghrelin receptor (GHS-R1a), a NMR study using living cells. Bioorg Med Chem 2010; 18:1583-90. [DOI: 10.1016/j.bmc.2010.01.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Revised: 12/24/2009] [Accepted: 01/02/2010] [Indexed: 02/02/2023]
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Seim I, Herington AC, Chopin LK. New insights into the molecular complexity of the ghrelin gene locus. Cytokine Growth Factor Rev 2009; 20:297-304. [DOI: 10.1016/j.cytogfr.2009.07.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Yin X, Li Y, Xu G, An W, Zhang W. Ghrelin fluctuation, what determines its production? Acta Biochim Biophys Sin (Shanghai) 2009; 41:188-97. [PMID: 19280057 DOI: 10.1093/abbs/gmp001] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Ghrelin, a 28 amino acid gut brain peptide, acts as an endogenous ligand for its receptor, the growth hormone secretagogue receptor, to exercise a variety of functions ranging from stimulation of growth hormone secretion, regulation of appetite and energy metabolism, and cell protection to modulation of inflammation. This review summarizes the advance in the regulation of ghrelin expression and secretion. We introduce the structure of ghrelin promoter, the processing and modification of ghrelin precursor, and the regulation mechanism in these processes. Then we discuss factors found to be important in the regulation of ghrelin production, including nutrients, hormones, and autonomic nervous system. Finally, we outline the alteration in the level of ghrelin in certain physiological and pathological status.
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Affiliation(s)
- Xuefeng Yin
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing 100191, China
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