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Szlis M, Wójcik-Gładysz A, Przybył BJ. Central obestatin administration affect the LH and FSH secretory activity in peripubertal sheep. Theriogenology 2020; 145:10-17. [PMID: 31982689 DOI: 10.1016/j.theriogenology.2020.01.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/14/2020] [Accepted: 01/14/2020] [Indexed: 02/06/2023]
Abstract
Obestatin - a 23 amino acid peptide is synthesized as another product of the ghrl gene and its synthesis occurs mainly in gastric mucosa cells. This hormone is involved in complex gut-brain neurohormonal networks, thereby can participates in the modulation of gonadotrophic axis activity. The aim of this study was to investigate the consequence of intracerebroventricular infusions of obestatin on LH and FSH pituitary cells secretory activity in peripubertal female sheep. Animals were randomly divided into two groups: the control group (n = 14) received intracerebroventricular infusions of Ringer-Lock solution (120 μL h-1), and the obestatin group (n = 14) was infused with obestatin (25 μg/120 μL h-1) diluted in Ringer-Lock solution. A series of four infusions was performed on three consecutive days. Blood samples were collected on day 0 and day 3. The sheep were slaughtered immediately after the end of the experiment. For molecular biological analysis, pituitaries from 7 sheep from each group (n = 7 + 7) were prepared and frozen in liquid nitrogen immediately after collection and then stored at -80 °C until Real Time RT-qPCR and RIA analyzes. For immunohistochemical analysis, pituitary tissues from the remaining animals (n = 7 + 7) was fixed in situ for further examination. Real-Time qPCR and immunohistochemistry analyses revealed substantial changes in the LH and FSH pituitary cells secretory activity in obestatin-infused sheep. Exogenous obestatin administration reduced LHβ mRNA expression and increased the accumulation of immunoreactive LH in gonadotrophic cells of the adenohypophysis. These changes were accompanied by a decrease in the mean LH concentration in the peripheral blood resulting from the lower LH pulse amplitude. Moreover, an increase in both FSHβ mRNA expression and FSH immunoreactivity and amount in pituitary cells were noted, while mean blood FSH concentration remained unchanged after obestatin treatment. The obtained results showed that exogenous obestatin affected LH secretory activity at the level of protein synthesis, accumulation and release as well as obestatin increase FSHβ mRNA expression and accumulation of this hormone but at the same time have no effect on FSH release to blood. Thus, obestatin can participate in the neuroendocrine network, which modulates gonadotrophic axis activity in sheep.
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Affiliation(s)
- Michał Szlis
- Department of Animal Physiology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110, Jabłonna, Poland
| | - Anna Wójcik-Gładysz
- Department of Animal Physiology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110, Jabłonna, Poland.
| | - Bartosz Jarosław Przybył
- Department of Animal Physiology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110, Jabłonna, Poland
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Wójcik-Gładysz A, Szlis M, Przybył BJ, Polkowska J. Obestatin may affect the GnRH/KNDy gene network in sheep hypothalamus. Res Vet Sci 2019; 123:51-58. [DOI: 10.1016/j.rvsc.2018.12.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 12/15/2018] [Accepted: 12/17/2018] [Indexed: 02/06/2023]
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Beberashvili I, Katkov A, Sinuani I, Azar A, Shapiro G, Feldman L, Gorelik O, Stav K, Efrati S. Serum Obestatin: A Biomarker of Cardiovascular and All-Cause Mortality in Hemodialysis Patients. Am J Nephrol 2018; 47:254-265. [PMID: 29694945 DOI: 10.1159/000488285] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Accepted: 03/07/2018] [Indexed: 01/10/2023]
Abstract
BACKGROUND Recent experimental studies have suggested that obestatin, a proposed anorexigenic gut hormone and a physiological opponent of acyl-ghrelin, has protective cardiovascular effects. We tested the hypothesis that obestatin is independent of inflammatory mediators and/or acyl-ghrelin in predicting outcomes of the maintenance hemodialysis (MHD) population. METHODS It was a 6-year cohort study on 261 MHD patients. Obestatin, acyl-ghrelin, adipokines (leptin and adiponectin), markers of inflammation and nutrition, prospective all-cause and cardiovascular mortality were studied. RESULTS During the follow-up, 160 patients died in total, with 74 deaths due to cardiovascular causes. For each ng/mL increase in baseline obestatin level in fully adjusted models (including malnutrition-inflammation score, Interleukin-6 [IL-6], adipokines and acyl-ghrelin), the hazard for death from all causes was 0.90 (95% CI 0.81-0.99) and for cardiovascular death 0.85 (95% CI 0.73-0.99). However, these associations were more robust in the subgroup of patients aged above 71 years: 0.85 (95% CI 0.73-0.98) for all-cause death and 0.66 (95% CI 0.52-0.85) for cardiovascular death. An interaction between high IL-6 (above median) and low obestatin (below median) levels for increased risk of all-cause mortality (synergy index [SI] 5.14, p = 0.001) and cardiovascular mortality (SI 4.81, p = 0.02) emerged in the development of multivariable adjusted models. Interactions were also observed between obestatin, Tumor necrosis factor-alpha, adipokines and acyl-ghrelin, which were associated with mortality risk. CONCLUSION Serum obestatin behaves as a biomarker for cardiovascular and all-cause mortality in MHD patients. The prognostic ability of obestatin in this regard is independent of inflammation, nutritional status, acyl-ghrelin's and adipokines' activity and is modified by age being very prominent in patients older than 71 years.
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Affiliation(s)
- Ilia Beberashvili
- Division of Nephrology, Assaf Harofeh Medical Center, Affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | - Anna Katkov
- Division of Nephrology, Assaf Harofeh Medical Center, Affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | - Inna Sinuani
- Department of Pathology, Assaf Harofeh Medical Center, Affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | - Ada Azar
- Department of Nutrition, Assaf Harofeh Medical Center, Affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | - Gregory Shapiro
- Division of Nephrology, Assaf Harofeh Medical Center, Affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | - Leonid Feldman
- Division of Nephrology, Assaf Harofeh Medical Center, Affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | - Oleg Gorelik
- Department of Internal Medicine F, Assaf Harofeh Medical Center, Affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | - Kobi Stav
- Department of Urology, Assaf Harofeh Medical Center, Affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | - Shai Efrati
- Division of Nephrology, Assaf Harofeh Medical Center, Affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
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Szlis M, Polkowska J, Skrzeczyńska E, Przybył BJ, Wójcik-Gładysz A. Does obestatin modulate the hypothalamic appetite-regulating network in peripubertal sheep? J Anim Physiol Anim Nutr (Berl) 2018; 102:690-700. [DOI: 10.1111/jpn.12879] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 01/28/2018] [Indexed: 12/12/2022]
Affiliation(s)
- M. Szlis
- Department of Animal Physiology; The Kielanowski Institute of Animal Physiology and Nutrition; Polish Academy of Sciences; Jabłonna Poland
| | - J. Polkowska
- Department of Animal Physiology; The Kielanowski Institute of Animal Physiology and Nutrition; Polish Academy of Sciences; Jabłonna Poland
| | - E. Skrzeczyńska
- Department of Animal Physiology; The Kielanowski Institute of Animal Physiology and Nutrition; Polish Academy of Sciences; Jabłonna Poland
| | - B. J. Przybył
- Department of Animal Physiology; The Kielanowski Institute of Animal Physiology and Nutrition; Polish Academy of Sciences; Jabłonna Poland
| | - A. Wójcik-Gładysz
- Department of Animal Physiology; The Kielanowski Institute of Animal Physiology and Nutrition; Polish Academy of Sciences; Jabłonna Poland
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Green BD, Grieve DJ. Biochemical properties and biological actions of obestatin and its relevence in type 2 diabetes. Peptides 2018; 100:249-259. [PMID: 29412827 DOI: 10.1016/j.peptides.2017.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/05/2017] [Accepted: 12/06/2017] [Indexed: 12/15/2022]
Abstract
Obestatin was initially discovered in rat stomach extract, and although it is principally produced in the gastric mucosa, it can be found throughout the gastrointestinal tract. This 23-amino acid C-terminally amidated peptide is derived from preproghrelin and has been ascribed a wide range of metabolic effects relevant to type 2 diabetes. Obestatin reportedly inhibits gastrointestinal motility, reduces food intake and lowers body weight and improves lipid metabolism. Furthermore, it appears to exert actions on the pancreatic β-cell, most notably increasing β-cell mass and upregulating genes associated with insulin production and β-cell regeneration, with relevance to type 2 diabetes. It is becoming evident that obestatin also exerts pleiotropic effects on the cardiovascular system, possibly modulating blood pressure, endothelial function and triggering cardioprotective mechanisms, which may be important in determining cardiovascular outcomes in type 2 diabetes. Furthermore, it seems that like other gut peptides obestatin has neuroprotective properties. This review examines the biochemical properties of the obestatin peptide (its structure, sequence, stability and distribution) and the candidate receptors through which it may act. It provides a balanced examination of the reported pancreatic and extrapancreatic actions of obestatin and evaluates its potential relevance with respect to diabetes therapy, together with discussion of direct evidence linking alterations in obestatin signalling with obesity/diabetes and other diseases.
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Affiliation(s)
- Brian D Green
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, BT9 5BN, UK.
| | - David J Grieve
- Centre for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7AE, UK
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Obestatin stimulates the somatotrophic axis activity in sheep. Brain Res 2018; 1678:278-287. [DOI: 10.1016/j.brainres.2017.10.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 09/25/2017] [Accepted: 10/31/2017] [Indexed: 01/12/2023]
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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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Hassouna R, Labarthe A, Tolle V. Hypothalamic regulation of body growth and appetite by ghrelin-derived peptides during balanced nutrition or undernutrition. Mol Cell Endocrinol 2016; 438:42-51. [PMID: 27693419 DOI: 10.1016/j.mce.2016.09.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 09/25/2016] [Accepted: 09/26/2016] [Indexed: 12/16/2022]
Abstract
Among the gastrointestinal hormones that regulate food intake and energy homeostasis, ghrelin plays a unique role as the first one identified to increases appetite and stimulate GH secretion. This review highlights the latest mechanism by which ghrelin modulates body growth, appetite and energy metabolism by exploring pharmacological actions of the hormone and consequences of genetic or pharmacological blockade of the ghrelin/GHS-R (Growth Hormone Secretagogue Receptor) system on physiological responses in specific nutritional situations. Within the hypothalamus, novel mechanisms of action of this hormone involve its interaction with other ghrelin-derived peptides, such as desacyl ghrelin and obestatin, which are thought to act as functional ghrelin antagonists, and possible modulation of the GHS-R with other G-protein coupled receptors. During chronic undernutrition such as anorexia nervosa, variations of ghrelin-derived peptides may be an adaptative metabolic response to maintain normal glycemic control. Interestingly, some of ghrelin's metabolic actions are thought to be relayed through modulation of GH, an anabolic and hyperglycemic agent.
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Affiliation(s)
- Rim Hassouna
- UMR-S 894 INSERM, Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, 2 ter rue d'Alésia, 75014, Paris, France; Naomi Berrie Diabetes Center, Department of Pediatrics, Columbia University Medical Center, New York, NY, 10032, USA
| | - Alexandra Labarthe
- UMR-S 894 INSERM, Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, 2 ter rue d'Alésia, 75014, Paris, France
| | - Virginie Tolle
- UMR-S 894 INSERM, Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, 2 ter rue d'Alésia, 75014, Paris, France.
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Cowan E, Burch KJ, Green BD, Grieve DJ. Obestatin as a key regulator of metabolism and cardiovascular function with emerging therapeutic potential for diabetes. Br J Pharmacol 2016; 173:2165-81. [PMID: 27111465 DOI: 10.1111/bph.13502] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 04/05/2016] [Accepted: 04/15/2016] [Indexed: 01/01/2023] Open
Abstract
Obestatin is a 23-amino acid C-terminally amidated gastrointestinal peptide derived from preproghrelin and which forms an α helix. Although obestatin has a short biological half-life and is rapidly degraded, it is proposed to exert wide-ranging pathophysiological actions. Whilst the precise nature of many of its effects is unclear, accumulating evidence supports positive actions on both metabolism and cardiovascular function. For example, obestatin has been reported to inhibit food and water intake, body weight gain and gastrointestinal motility and also to mediate promotion of cell survival and prevention of apoptosis. Obestatin-induced increases in beta cell mass, enhanced adipogenesis and improved lipid metabolism have been noted along with up-regulation of genes associated with beta cell regeneration, insulin production and adipogenesis. Furthermore, human circulating obestatin levels generally demonstrate an inverse association with obesity and diabetes, whilst the peptide has been shown to confer protective metabolic effects in experimental diabetes, suggesting that it may hold therapeutic potential in this setting. Obestatin also appears to be involved in blood pressure regulation and to exert beneficial effects on endothelial function, with experimental studies indicating that it may also promote cardioprotective actions against, for example, ischaemia-reperfusion injury. This review will present a critical appraisal of the expanding obestatin research area and discuss the emerging therapeutic potential of this peptide for both metabolic and cardiovascular complications of diabetes.
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Affiliation(s)
- Elaine Cowan
- Queen's University Belfast, Institute for Global Food Security, School of Biological Sciences, Belfast, UK
| | - Kerry J Burch
- Queen's University Belfast, Wellcome-Wolfson Institute for Experimental Medicine, Belfast, UK
| | - Brian D Green
- Queen's University Belfast, Institute for Global Food Security, School of Biological Sciences, Belfast, UK
| | - David J Grieve
- Queen's University Belfast, Wellcome-Wolfson Institute for Experimental Medicine, Belfast, UK
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Lemarié F, Beauchamp E, Legrand P, Rioux V. Revisiting the metabolism and physiological functions of caprylic acid (C8:0) with special focus on ghrelin octanoylation. Biochimie 2015; 120:40-8. [PMID: 26253695 DOI: 10.1016/j.biochi.2015.08.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 08/01/2015] [Indexed: 12/22/2022]
Abstract
Caprylic acid (octanoic acid, C8:0) belongs to the class of medium-chain saturated fatty acids (MCFAs). Dairy products and specific oils like coconut oil are natural sources of dietary C8:0 but higher intakes of this fatty acid can be provided with MCT (Medium-Chain Triglycerides) oil that consists in 75% of C8:0. MCFAs have physical and metabolic properties that are distinct from those of long-chain saturated fatty acids (LCFAs ≥ 12 carbons). Beneficial physiological effects of dietary C8:0 have been studied for a long time and MCT oil has been used as a special energy source for patients suffering from pancreatic insufficiency, impaired lymphatic chylomicron transport and fat malabsorption. More recently, caprylic acid was also shown to acylate ghrelin, the only known peptide hormone with an orexigenic effect. Through its covalent binding to the ghrelin peptide, caprylic acid exhibits an emerging and specific role in modulating physiological functions themselves regulated by octanoylated ghrelin. Dietary caprylic acid is therefore now suspected to provide the ghrelin O-acyltransferase (GOAT) enzyme with octanoyl-CoA co-substrates necessary for the acyl modification of ghrelin. This review tries to highlight the discrepancy between the formerly described beneficial effects of dietary MCFAs on body weight loss and the C8:0 newly reported effect on appetite stimulation via ghrelin octanoylation. The subsequent aim of this review is to demonstrate the relevance of carrying out further studies to better understand the physiological functions of this particular fatty acid.
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Affiliation(s)
- Fanny Lemarié
- Laboratoire de Biochimie-Nutrition Humaine, Agrocampus Ouest, INRA USC 1378, Rennes, France
| | - Erwan Beauchamp
- Laboratoire de Biochimie-Nutrition Humaine, Agrocampus Ouest, INRA USC 1378, Rennes, France
| | - Philippe Legrand
- Laboratoire de Biochimie-Nutrition Humaine, Agrocampus Ouest, INRA USC 1378, Rennes, France
| | - Vincent Rioux
- Laboratoire de Biochimie-Nutrition Humaine, Agrocampus Ouest, INRA USC 1378, Rennes, France.
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Yuan X, Cai W, Liang XF, Su H, Yuan Y, Li A, Tao YX. Obestatin partially suppresses ghrelin stimulation of appetite in "high-responders" grass carp, Ctenopharyngodon idellus. Comp Biochem Physiol A Mol Integr Physiol 2015; 184:144-9. [PMID: 25737031 DOI: 10.1016/j.cbpa.2015.02.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 01/01/2015] [Accepted: 02/23/2015] [Indexed: 12/17/2022]
Abstract
Ghrelin and obestatin are two gastrointestinal peptides obtained by post-translational processing of a common precursor, preproghrelin. The effect of obestatin on food intake is still controversial. The aim of the present study was to investigate the effects of ghrelin and obestatin on food intake in grass carp, Ctenopharyngodon idellus. Fish received intraperitoneal (IP) injection of saline, ghrelin (100 ng g(-1)BW), obestatin-like (25 ng g(-1)BW) and ghrelin in combination with obestatin-like. Ghrelin stimulation of food intake varied considerably among individual fish with 70.8% eliciting a robust response. In these high-responders, food intake was significantly increased by IP ghrelin within 2 h. Co-administration of ghrelin and obestatin-like resulted in a decrease in food intake, indicating that obestatin was able to antagonize the effect of ghrelin. However, IP obestatin-like alone could not regulate food intake in grass carp. RT-PCR analysis demonstrated that IP ghrelin peptide led to a significant increase in mRNA abundance of NPY, Y8a and Y8b genes compared to saline injected fish, while in combination with obestatin-like peptide decreased ghrelin-induced gene expressions of these three genes. IP sole obestatin-like peptide did not modify the expression levels of NPY, Y8a, Y8b, CART and POMC compared to the control group. Therefore, IP administration of obestatin-like peptide, partially blocking the ghrelin-induced appetite, investigated the possible involvement of obestatin as a mediator of the ghrelin stimulatory action on food intake, at least in "high-responders" grass carp.
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Affiliation(s)
- Xiaochen Yuan
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Hubei Collaborative Innovation Center for Freshwater Aquaculture, Wuhan, Hubei 430070, China
| | - Wenjing Cai
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Hubei Collaborative Innovation Center for Freshwater Aquaculture, Wuhan, Hubei 430070, China
| | - Xu-Fang Liang
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Hubei Collaborative Innovation Center for Freshwater Aquaculture, Wuhan, Hubei 430070, China.
| | - Hang Su
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Hubei Collaborative Innovation Center for Freshwater Aquaculture, Wuhan, Hubei 430070, China
| | - Yongchao Yuan
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Hubei Collaborative Innovation Center for Freshwater Aquaculture, Wuhan, Hubei 430070, China.
| | - Aixuan Li
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Hubei Collaborative Innovation Center for Freshwater Aquaculture, Wuhan, Hubei 430070, China
| | - Ya-Xiong Tao
- College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, Hubei 430070, China; Hubei Collaborative Innovation Center for Freshwater Aquaculture, Wuhan, Hubei 430070, China
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Sobrino Crespo C, Perianes Cachero A, Puebla Jiménez L, Barrios V, Arilla Ferreiro E. Peptides and food intake. Front Endocrinol (Lausanne) 2014; 5:58. [PMID: 24795698 PMCID: PMC4005944 DOI: 10.3389/fendo.2014.00058] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 04/09/2014] [Indexed: 12/19/2022] Open
Abstract
The mechanisms for controlling food intake involve mainly an interplay between gut, brain, and adipose tissue (AT), among the major organs. Parasympathetic, sympathetic, and other systems are required for communication between the brain satiety center, gut, and AT. These neuronal circuits include a variety of peptides and hormones, being ghrelin the only orexigenic molecule known, whereas the plethora of other factors are inhibitors of appetite, suggesting its physiological relevance in the regulation of food intake and energy homeostasis. Nutrients generated by food digestion have been proposed to activate G-protein-coupled receptors on the luminal side of enteroendocrine cells, e.g., the L-cells. This stimulates the release of gut hormones into the circulation such as glucagon-like peptide-1 (GLP-1), oxyntomodulin, pancreatic polypeptides, peptide tyrosine tyrosine, and cholecystokinin, which inhibit appetite. Ghrelin is a peptide secreted from the stomach and, in contrast to other gut hormones, plasma levels decrease after a meal and potently stimulate food intake. Other circulating factors such as insulin and leptin relay information regarding long-term energy stores. Both hormones circulate at proportional levels to body fat content, enter the CNS proportionally to their plasma levels, and reduce food intake. Circulating hormones can influence the activity of the arcuate nucleus (ARC) neurons of the hypothalamus, after passing across the median eminence. Circulating factors such as gut hormones may also influence the nucleus of the tractus solitarius (NTS) through the adjacent circumventricular organ. On the other hand, gastrointestinal vagal afferents converge in the NTS of the brainstem. Neural projections from the NTS, in turn, carry signals to the hypothalamus. The ARC acts as an integrative center, with two major subpopulations of neurons influencing appetite, one of them coexpressing neuropeptide Y and agouti-related protein (AgRP) that increases food intake, whereas the other subpopulation coexpresses pro-opiomelanocortin (POMC) and cocaine and amphetamine-regulated transcript that inhibits food intake. AgRP antagonizes the effects of the POMC product, α-melanocyte-stimulating hormone (α-MSH). Both populations project to areas important in the regulation of food intake, including the hypothalamic paraventricular nucleus, which also receives important inputs from other hypothalamic nuclei.
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Affiliation(s)
- Carmen Sobrino Crespo
- Biochemistry and Molecular Biology Unit, Department of Systems Biology, Faculty of Medicine, University of Alcalá, Alcalá de Henares, Spain
| | - Aránzazu Perianes Cachero
- Biochemistry and Molecular Biology Unit, Department of Systems Biology, Faculty of Medicine, University of Alcalá, Alcalá de Henares, Spain
| | - Lilian Puebla Jiménez
- Biochemistry and Molecular Biology Unit, Department of Systems Biology, Faculty of Medicine, University of Alcalá, Alcalá de Henares, Spain
| | - Vicente Barrios
- Department of Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación La Princesa, Madrid, Spain
- Centro de Investigación Biomédica en Red Fisiopatología Obesidad y Nutrición, Instituto de Salud Carlos III, Madrid, Spain
| | - Eduardo Arilla Ferreiro
- Biochemistry and Molecular Biology Unit, Department of Systems Biology, Faculty of Medicine, University of Alcalá, Alcalá de Henares, Spain
- *Correspondence: Eduardo Arilla Ferreiro, Biochemistry and Molecular Biology Unit, Department of Systems Biology, Faculty of Medicine, University of Alcalá, Alcalá de Henares, Madrid E-28871, Spain e-mail:
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Low serum concentration of obestatin as a predictor of mortality in maintenance hemodialysis patients. BIOMED RESEARCH INTERNATIONAL 2013; 2013:796586. [PMID: 24102059 PMCID: PMC3786512 DOI: 10.1155/2013/796586] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 07/19/2013] [Indexed: 12/04/2022]
Abstract
Obestatin, a proposed anorexigenic gut hormone, has been shown to have a number of beneficial cardiotropic effects in experimental studies. We hypothesized that obestatin alteration in hemodialysis patients may link to clinical outcomes. This cross-sectional study with prospective followup for almost 4 years was performed on 94 prevalent hemodialysis patients. Obestatin, leptin, proinflammatory cytokines (tumor necrosis factor-α [TNF-α], interleukin-6, and various nutritional markers were measured. Patients with low obestatin levels, defined as a level less than median, had a worse all-cause mortality and cardiovascular mortality. The crude all-cause (HR 2.23, 95% CI 1.17 to 4.24) and cardiovascular mortality hazard ratios (HR 4.03, 95% CI 1.27 to 12.76) in these patients continued to be significant after adjustment for various confounders for all-cause mortality. Across the four obestatin-TNF-α categories, the group with low obestatin and high TNF-α (above median level) exhibited a worse outcome in both all-cause mortality and cardiovascular mortality. Clinical characteristics of patients in low obestatin high TNF-α group did not differ from other obestatin-TNF-α categorized groups. In summary, low serum obestatin concentration is an independent predictor of mortality in prevalent hemodialysis patients. Novel interactions were observed between obestatin and TNF-α, which were associated with mortality risk, especially those due to cardiovascular causes.
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Ren G, He Z, Cong P, Chen H, Guo Y, Yu J, Liu Z, Ji Q, Song Z, Chen Y. Peripheral administration of TAT-obestatin can influence the expression of liporegulatory genes but fails to affect food intake in mice. Peptides 2013; 42:8-14. [PMID: 23313740 DOI: 10.1016/j.peptides.2013.01.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 01/03/2013] [Accepted: 01/03/2013] [Indexed: 12/14/2022]
Abstract
Obestatin is a 23-amino-acid peptide originally regarded as an anorexigenic factor. However, most of the subsequent studies failed to confirm the initially reported anorexigenic properties of obestatin. Obestatin is incapable of crossing the blood brain barrier (BBB), which may affect its biological function. Here, we report the physiological effects of obestatin in mice after intraperitoneal administration of obestatin conjugated to the cell-permeable peptide TAT, which is capable of delivering different types of proteins through the BBB. Acute peripheral administration of 1 μmol/kg of TAT-obestatin did not influence the 24 h cumulative food intake and body weight gain of mice that were fasted for 18 h. Fed mice were injected intraperitoneally with 100 nmol/kg of TAT-obestatin daily for 25 d. Compared with control groups, on day 3, the gain in body weight was significantly altered; on day 7, abdominal fat mass was remarkably reduced; however, on day 25, there was a surprisingly notable increase in abdominal and epididymal fat mass. In comparison with control groups, on day 25, the expression levels of adiponectin, ADD1, C/EBPα, PPARG and GLUT4 were significantly up-regulated in liver tissues; in white adipose tissue, the expression level of C/EBPα was significantly up-regulated, but adiponectin and GLUT4 were significantly down-regulated. In addition, GPR39, the suspected receptor of obestatin, was up-regulated in white adipose tissue on day 25. These findings suggest that TAT-obestatin might play a role in white adipose tissue metabolism, but its physiological effects on food intake and body weight gain regulation remain unclear.
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Affiliation(s)
- Guangcai Ren
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510006, People's Republic of China
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16
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Smitka K, Papezova H, Vondra K, Hill M, Hainer V, Nedvidkova J. The role of "mixed" orexigenic and anorexigenic signals and autoantibodies reacting with appetite-regulating neuropeptides and peptides of the adipose tissue-gut-brain axis: relevance to food intake and nutritional status in patients with anorexia nervosa and bulimia nervosa. Int J Endocrinol 2013; 2013:483145. [PMID: 24106499 PMCID: PMC3782835 DOI: 10.1155/2013/483145] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 07/11/2013] [Indexed: 12/13/2022] Open
Abstract
Eating disorders such as anorexia (AN) and bulimia nervosa (BN) are characterized by abnormal eating behavior. The essential aspect of AN is that the individual refuses to maintain a minimal normal body weight. The main features of BN are binge eating and inappropriate compensatory methods to prevent weight gain. The gut-brain-adipose tissue (AT) peptides and neutralizing autoantibodies play an important role in the regulation of eating behavior and growth hormone release. The mechanisms for controlling food intake involve an interplay between gut, brain, and AT. Parasympathetic, sympathetic, and serotoninergic systems are required for communication between brain satiety centre, gut, and AT. These neuronal circuits include neuropeptides ghrelin, neuropeptide Y (NPY), peptide YY (PYY), cholecystokinin (CCK), leptin, putative anorexigen obestatin, monoamines dopamine, norepinephrine (NE), serotonin, and neutralizing autoantibodies. This extensive and detailed report reviews data that demonstrate that hunger-satiety signals play an important role in the pathogenesis of eating disorders. Neuroendocrine dysregulations of the AT-gut-brain axis peptides and neutralizing autoantibodies may result in AN and BN. The circulating autoantibodies can be purified and used as pharmacological tools in AN and BN. Further research is required to investigate the orexigenic/anorexigenic synthetic analogs and monoclonal antibodies for potential treatment of eating disorders in clinical practice.
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Affiliation(s)
- Kvido Smitka
- Institute of Endocrinology, Laboratory of Clinical and Experimental Neuroendocrinology, Narodni 8, 116 94 Prague 1, Czech Republic
| | - Hana Papezova
- Psychiatric Clinic, First Faculty of Medicine, Charles University, Ke Karlovu 11, 121 08 Prague 2, Czech Republic
| | - Karel Vondra
- Institute of Endocrinology, Laboratory of Clinical and Experimental Neuroendocrinology, Narodni 8, 116 94 Prague 1, Czech Republic
| | - Martin Hill
- Institute of Endocrinology, Laboratory of Clinical and Experimental Neuroendocrinology, Narodni 8, 116 94 Prague 1, Czech Republic
| | - Vojtech Hainer
- Institute of Endocrinology, Laboratory of Clinical and Experimental Neuroendocrinology, Narodni 8, 116 94 Prague 1, Czech Republic
| | - Jara Nedvidkova
- Institute of Endocrinology, Laboratory of Clinical and Experimental Neuroendocrinology, Narodni 8, 116 94 Prague 1, Czech Republic
- *Jara Nedvidkova:
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Hassouna R, Zizzari P, Viltart O, Yang SK, Gardette R, Videau C, Badoer E, Epelbaum J, Tolle V. A natural variant of obestatin, Q90L, inhibits ghrelin's action on food intake and GH secretion and targets NPY and GHRH neurons in mice. PLoS One 2012; 7:e51135. [PMID: 23251435 PMCID: PMC3519497 DOI: 10.1371/journal.pone.0051135] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 10/29/2012] [Indexed: 01/04/2023] Open
Abstract
Background Ghrelin and obestatin are two gut-derived peptides originating from the same ghrelin/obestatin prepropeptide gene (GHRL). While ghrelin stimulates growth hormone (GH) secretion and food intake and inhibits γ-aminobutyric-acid synaptic transmission onto GHRH (Growth Hormone Releasing Hormone) neurons, obestatin blocks these effects. In Humans, GHRL gene polymorphisms have been associated with pathologies linked to an unbalanced energy homeostasis. We hypothesized that one polymorphism located in the obestatin sequence (Q to L substitution in position 90 of the ghrelin/obestatin prepropeptide, rs4684677) may impact on the function of obestatin. In the present study, we tested the activity of native and Q90L obestatin to modulate ghrelin-induced food intake, GH secretion, cFos activity in GHRH and Neuropeptide Y (NPY) neurons and γ-aminobutyric-acid activity onto GHRH neurons. Methodology/Principal findings Food intake, GH secretion and electrophysiological recordings were assessed in C57BL/6 mice. cFos activity was measured in NPY-Renilla-GFP and GHRH-eGFP mice. Mice received saline, ghrelin or ghrelin combined to native or Q90L obestatin (30 nmol each) in the early light phase. Ghrelin stimulation of food intake and GH secretion varied considerably among individual mice with 59–77% eliciting a robust response. In these high-responders, ghrelin-induced food intake and GH secretion were reduced equally by native and Q90L obestatin. In contrast to in vivo observations, Q90L was slightly more efficient than native obestatin in inhibiting ghrelin-induced cFos activation within the hypothalamic arcuate nucleus and the nucleus tractus solitarius of the brainstem. After ghrelin injection, 26% of NPY neurons in the arcuate nucleus expressed cFos protein and this number was significantly reduced by co-administration of Q90L obestatin. Q90L was also more potent that native obestatin in reducing ghrelin-induced inhibition of γ-aminobutyric-acid synaptic transmission onto GHRH neurons. Conclusions/Significance These data support the hypothesis that Q90L obestatin partially blocks ghrelin-induced food intake and GH secretion by acting through NPY and GHRH neurons.
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Affiliation(s)
- Rim Hassouna
- UMR-S 894 INSERM, Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Philippe Zizzari
- UMR-S 894 INSERM, Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Odile Viltart
- UMR 837 INSERM, Laboratoire “Développement et Plasticité du Cerveau Postnatal”, Centre de Recherches JPARC, Lille and Université Lille Nord de France (USTL- Lille 1), Lille, France
| | - Seung-Kwon Yang
- School of Biomedical Sciences, The University of Queensland, Skerman Building (65), St Lucia, Queensland, Australia
| | - Robert Gardette
- UMR-S 894 INSERM, Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Catherine Videau
- UMR-S 894 INSERM, Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Emilio Badoer
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Bundoora, Melbourne, Victoria, Australia
| | - Jacques Epelbaum
- UMR-S 894 INSERM, Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Virginie Tolle
- UMR-S 894 INSERM, Centre de Psychiatrie et Neurosciences, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
- * E-mail:
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18
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Chopin LK, Seim I, Walpole CM, Herington AC. The ghrelin axis--does it have an appetite for cancer progression? Endocr Rev 2012; 33:849-91. [PMID: 22826465 DOI: 10.1210/er.2011-1007] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ghrelin, the endogenous ligand for the GH secretagogue receptor (GHSR), is a peptide hormone with diverse physiological roles. Ghrelin regulates GH release, appetite and feeding, gut motility, and energy balance and also has roles in the cardiovascular, immune, and reproductive systems. Ghrelin and the GHSR are expressed in a wide range of normal and tumor tissues, and a fluorescein-labeled, truncated form of ghrelin is showing promise as a biomarker for prostate cancer. Plasma ghrelin levels are generally inversely related to body mass index and are unlikely to be useful as a biomarker for cancer, but may be useful as a marker for cancer cachexia. Some single nucleotide polymorphisms in the ghrelin and GHSR genes have shown associations with cancer risk; however, larger studies are required. Ghrelin regulates processes associated with cancer, including cell proliferation, apoptosis, cell migration, cell invasion, inflammation, and angiogenesis; however, the role of ghrelin in cancer is currently unclear. Ghrelin has predominantly antiinflammatory effects and may play a role in protecting against cancer-related inflammation. Ghrelin and its analogs show promise as treatments for cancer-related cachexia. Further studies using in vivo models are required to determine whether ghrelin has a role in cancer progression.
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Affiliation(s)
- Lisa K Chopin
- Ghrelin Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology and Australian Prostate Cancer Research Centre-Queensland, Brisbane, Queensland 4001, Australia.
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19
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Functional and structural features of adipokine family. Cytokine 2012; 61:1-14. [PMID: 23022179 DOI: 10.1016/j.cyto.2012.08.036] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 08/29/2012] [Accepted: 08/31/2012] [Indexed: 12/13/2022]
Abstract
In the mid-1990s, the interest in adipose tissue was revived by the discovery of leptin. Since then numerous other hormones have been isolated from white adipose tissue that has no longer considered an inert tissue mainly devoted to energy storage but emerged as an active participant in regulating physiologic and pathologic processes, including immunity and inflammation. Adipose tissue produces and releases a variety of proinflammatory and anti-inflammatory factors, including the adipokines, as well as cytokines and chemokines. Proinflammatory molecules produced by adipose tissue have been implicated as active participants in the development of insulin resistance and the increased risk of cardiovascular disease associated with obesity. In contrast, reduced leptin levels might predispose to increased susceptibility to infection caused by reduced T-cell responses in malnourished individuals. Altered adipokine levels have been observed in a variety of inflammatory conditions, although their pathogenic role has not been completely clarified. In this paper we want to review: (i) the role of adipose tissue in different biological processes, (ii) the functional and structural description of all the known adipokines subdivided in different subfamilies, (iii) the adipokine involvement in obesity and cancers, and (iv) the adipokine interactome.
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20
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Stengel A, Taché Y. Yin and Yang - the Gastric X/A-like Cell as Possible Dual Regulator of Food Intake. J Neurogastroenterol Motil 2012; 18:138-49. [PMID: 22523723 PMCID: PMC3325299 DOI: 10.5056/jnm.2012.18.2.138] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 03/11/2012] [Indexed: 01/14/2023] Open
Abstract
Ingestion of food affects secretion of hormones from enteroendocrine cells located in the gastrointestinal mucosa. These hormones are involved in the regulation of various gastrointestinal functions including the control of food intake. One cell in the stomach, the X/A-like has received much attention over the past years due to the production of ghrelin. Until now, ghrelin is the only known orexigenic hormone that is peripherally produced and centrally acting to stimulate food intake. Subsequently, additional peptide products of this cell have been described including desacyl ghrelin, obestatin and nesfatin-1. Desacyl ghrelin seems to be involved in the regulation of food intake as well and could play a counter-balancing role of ghrelin's orexigenic effect. In contrast, the initially proposed anorexigenic action of obestatin did not hold true and therefore the involvement of this peptide in the regulation of feeding is questionable. Lastly, the identification of nesfatin-1 in the same cell in different vesicles than ghrelin extended the function of this cell type to the inhibition of feeding. Therefore, this X/A-like cell could play a unique role by encompassing yin and yang properties to mediate not only hunger but also satiety.
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Affiliation(s)
- Andreas Stengel
- Department of Medicine, Division Psychosomatic Medicine and Psychotherapy, Charité, Campus Mitte, Universitätsmedizin Berlin, Berlin, Germany
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21
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De Spiegeleer B, Van Dorpe S, Vergote V, Wynendaele E, Pauwels E, Van De Wiele C, Garcia-Solis P, Solis-Sainz JC. In vitro metabolic stability of iodinated obestatin peptides. Peptides 2012; 33:272-8. [PMID: 22222609 DOI: 10.1016/j.peptides.2011.12.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 12/18/2011] [Accepted: 12/18/2011] [Indexed: 10/14/2022]
Abstract
Different iodinated mouse obestatin peptides have been characterized toward their in vitro stability in the main metabolic compartments plasma, liver and kidney. Using HPLC-UV for quantification, significant differences in the degradation kinetics of the iodinated peptides, arising from both enzymatic proteolysis and dehalogenation, were found when compared to the native, unmodified peptide. HPLC-MS/MS analysis demonstrated that the cleavage sites were dependent upon the biological matrix and the location of the amino acid residue incorporating the iodine atom(s). The degrading proteases were found to target peptide bonds further away from the iodine incorporation, while proteolytic cleavages of nearby peptide bonds were more limited. Diiodinated amino acid residue containing peptides were found to be more susceptible to deiodination than the mono-iodinated derivative. In plasma, the percentage of peptide degradation solely attributed to deiodinase activity after 20 min incubation reached up to 25% for 2,5-diiodo-H(19)-obestatin compared to 20% and only 3% for (3,5-diiodo-Y(16))- and (3-iodo-Y(16)) obestatin, respectively. Hence, our results demonstrate that the different iodinated peptides pose significantly different metabolization properties and thus, also different biological activities are expected for peptides upon iodination.
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Affiliation(s)
- Bart De Spiegeleer
- Drug Quality and Registration Group, Faculty of Pharmaceutical Sciences, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium.
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22
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Baragli A, Lanfranco F, Allasia S, Granata R, Ghigo E. Neuroendocrine and metabolic activities of ghrelin gene products. Peptides 2011; 32:2323-32. [PMID: 22056513 DOI: 10.1016/j.peptides.2011.10.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 10/03/2011] [Accepted: 10/25/2011] [Indexed: 12/15/2022]
Abstract
Acylated ghrelin (AG) is a 28 amino acid gastric peptide a natural ligand for the growth hormone secretagogue (GHS) receptor type 1a (GHS-R1a), endowed with GH-secreting and orexigenic properties. Besides, ghrelin exerts several peripheral metabolic actions, including modulation of glucose homeostasis and stimulation of adipogenesis. Notably, AG administration causes hyperglycemia in rodents as in humans. Ghrelin pleiotropy is supported by a widespread expression of the ghrelin gene, of GHS-R1a and other unknown ghrelin binding sites. The existence of alternative receptors for AG, of several natural ligands for GHS-R1a and of acylation-independent ghrelin non-neuroendocrine activities, suggests that there might be a complex 'ghrelin system' not yet completely explored. Moreover, the patho-physiological implications of unacylated ghrelin (UAG), and obestatin (Ob), the other two ghrelin gene-derived peptides, need to be clarified. Within the next few years, we may better understand the 'ghrelin system', where we might envisage clinical applications.
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Affiliation(s)
- Alessandra Baragli
- Laboratory of Molecular and Cellular Endocrinology, Division of Endocrinology, Department of Internal Medicine, University of Turin, Turin, Italy.
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23
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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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24
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Seim I, Walpole C, Amorim L, Josh P, Herington A, Chopin L. The expanding roles of the ghrelin-gene derived peptide obestatin in health and disease. Mol Cell Endocrinol 2011; 340:111-7. [PMID: 21459124 DOI: 10.1016/j.mce.2011.03.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/23/2011] [Accepted: 03/25/2011] [Indexed: 01/18/2023]
Abstract
Obestatin is a 23 amino acid, ghrelin gene-derived peptide hormone produced in the stomach and a range of other tissues throughout the body. While it was initially reported that obestatin opposed the actions of ghrelin with regards to appetite and food intake, it is now clear that obestatin is not an endogenous ghrelin antagonist, but it is a multi-functional peptide hormone in its own right. In this review we will discuss the controversies associated with the discovery of obestatin and explore emerging central and peripheral roles of obestatin, which includes adipogenesis, pancreatic homeostasis and cancer.
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Affiliation(s)
- Inge Seim
- Queensland University of Technology, Queensland, Brisbane, Australia
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25
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Stengel A, Taché Y. Interaction between gastric and upper small intestinal hormones in the regulation of hunger and satiety: ghrelin and cholecystokinin take the central stage. Curr Protein Pept Sci 2011; 12:293-304. [PMID: 21428875 PMCID: PMC3670092 DOI: 10.2174/138920311795906673] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 03/23/2011] [Indexed: 12/13/2022]
Abstract
Several peptides are produced and released from endocrine cells scattered within the gastric oxyntic and the small intestinal mucosa. These peptide hormones are crucially involved in the regulation of gastrointestinal functions and food intake by conveying their information to central regulatory sites located in the brainstem as well as in the forebrain, such as hypothalamic nuclei. So far, ghrelin is the only known hormone that is peripherally produced in gastric X/A-like cells and centrally acting to stimulate food intake, whereas the suppression of feeding seems to be much more redundantly controlled by a number of gut peptides. Cholecystokinin produced in the duodenum is a well established anorexigenic hormone that interacts with ghrelin to modulate food intake indicating a regulatory network located at the first site of contact with nutrients in the stomach and upper small intestine. In addition, a number of peptides including leptin, urocortin 2, amylin and glucagon-like peptide 1 interact synergistically with CCK to potentiate its satiety signaling effect. New developments have led to the identification of additional peptides in X/A-like cells either derived from the pro-ghrelin gene by alternative splicing and posttranslational processing (obestatin) or a distinct gene (nucleobindin2/nesfatin-1) which have been investigated for their influence on food intake.
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Affiliation(s)
- Andreas Stengel
- Department of Medicine, CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division UCLA, and VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Yvette Taché
- Department of Medicine, CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division UCLA, and VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
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26
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Li JB, Asakawa A, Cheng K, Li Y, Chaolu H, Tsai M, Inui A. Biological effects of obestatin. Endocrine 2011; 39:205-11. [PMID: 21424587 DOI: 10.1007/s12020-011-9453-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 02/05/2011] [Indexed: 10/18/2022]
Abstract
Obestatin, a 23-amino-acid peptide, is derived from the preproghrelin precursor. Obestatin was identified in 2005 as a hormone regulating food intake and energy, and having opposite effects to those of ghrelin. However, as studies have progressed, many disputes on the physiological function of obestatin have emerged. The food intake suppressive effects of obestatin have not been replicated in many studies. Nonetheless, many biological roles of obestatin have been revealed, and obestatin is thought to be associated with a variety of biological functions such as feeding, drinking, incretion, memory, and sleep, and with neuropsychiatric manifestations. The biological effects of obestatin will be reviewed in this article.
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Affiliation(s)
- Jiang-Bo Li
- Department of Social and Behavioral Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan
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Agnew A, Calderwood D, Chevallier OP, Greer B, Grieve DJ, Green BD. Chronic treatment with a stable obestatin analog significantly alters plasma triglyceride levels but fails to influence food intake; fluid intake; body weight; or body composition in rats. Peptides 2011; 32:755-62. [PMID: 21167891 DOI: 10.1016/j.peptides.2010.12.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 12/02/2010] [Accepted: 12/02/2010] [Indexed: 01/21/2023]
Abstract
Obestatin (OB(1-23) is a 23 amino acid peptide encoded on the preproghrelin gene, originally reported to have metabolic actions related to food intake, gastric emptying and body weight. The biological instability of OB(1-23) has recently been highlighted by studies demonstrating its rapid enzymatic cleavage in a number of biological matrices. We assessed the stability of both OB(1-23) and an N-terminally PEGylated analog (PEG-OB(1-23)) before conducting chronic in vivo studies. Peptides were incubated in rat liver homogenate and degradation monitored by LC-MS. PEG-OB(1-23) was approximately 3-times more stable than OB(1-23). Following a 14 day infusion of Sprague-Dawley rats with 50 nmol/kg/day of OB(1-23) or a N-terminally PEGylated analog (PEG-OB(1-23)), we found no changes in food/fluid intake, body weight and plasma glucose or cholesterol between groups. Furthermore, morphometric liver, muscle and white adipose tissue (WAT) weights and tissue triglyceride concentrations remained unaltered between groups. However, with stabilized PEG-OB(1-23) we observed a 40% reduction in plasma triglycerides. These findings indicate that PEG-OB(1-23) is an OB(1-23) analog with significantly enhanced stability and suggest that obestatin could play a role in modulating physiological lipid metabolism, although it does not appear to be involved in regulation of food/fluid intake, body weight or fat deposition.
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Affiliation(s)
- A Agnew
- School of Biological Sciences, Queens University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, UK
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Maier C, Riedl M, Vila G, Wolzt M, Clodi M, Ludvik B, Luger A. Differential regulation of plasma obestatin and ghrelin by meal intake and the cholinergic system in lean, but not obese individuals. J Clin Endocrinol Metab 2010; 95:E214-8. [PMID: 20660037 DOI: 10.1210/jc.2010-0243] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT Obestatin is cosecreted with and stemming from the same precursor as ghrelin and is apparently involved in energy metabolism. Relatively little is known about the regulation of obestatin release. OBJECTIVE The regulation of obestatin release and obestatin-to-ghrelin ratios by meal intake and the cholinergic system were studied in lean and obese subjects. DESIGN, PARTICIPANTS, AND SETTING We conducted a randomized, double-blind, placebo-controlled, crossover study with 4 study days in eight obese (body mass index >30 kg/m(2)) and eight matched lean (body mass index <25 kg/m(2)) healthy subjects (two males and six females per group) at a University Clinical Research Unit. INTERVENTIONS Atropine (1 mg iv) was administered alone and in combination with breakfast (550 kcal) intake, or placebo (isotonic saline) alone and in combination with breakfast. MAIN OUTCOME MEASURES We measured plasma obestatin and obestatin/ghrelin ratios. RESULTS Both obestatin and ghrelin/obestatin ratios decreased significantly from baseline by either atropine or meal intake in lean individuals, with the two effects adding up on the combined atropine/breakfast day. In contrast, there were no statistically significant differences in obese subjects, who also showed significantly greater association between ghrelin and obestatin values than their lean counterparts. CONCLUSIONS Obestatin and ghrelin release is differentially regulated by meal intake and the cholinergic system in lean individuals. This regulation is impaired in obesity.
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Affiliation(s)
- Christina Maier
- Department of Clinical Endocrinology and Metabolism, University Clinics of Medicine III, Medical University of Vienna, Vienna, Austria.
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Brunetti L, Di Nisio C, Recinella L, Orlando G, Ferrante C, Chiavaroli A, Leone S, Di Michele P, Shohreh R, Vacca M. Obestatin inhibits dopamine release in rat hypothalamus. Eur J Pharmacol 2010; 641:142-7. [PMID: 20553917 DOI: 10.1016/j.ejphar.2010.05.059] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 04/14/2010] [Accepted: 05/31/2010] [Indexed: 10/19/2022]
Abstract
We have investigated the effects of the gastric peptide obestatin injected into the arcuate nucleus of the rat hypothalamus on the hypothalamic mRNA expression of peptides which play master roles as feeding behavior modulators. We have also evaluated the effects of obestatin on dopamine, norepinephrine and serotonin release from rat hypothalamic synaptosomes in vitro. After 4 daily intrahypothalamic injections of obestatin (1 nmol/kg), we recorded a significant reduction of daily caloric intake and body weight gain. Gene expressions of either anorexigenic (cocaine- and amphetamine-regulated transcript, corticotropin releasing hormone, proopiomelanocortin) or orexigenic (agouti-related peptide, neuropeptide Y, orexin-A) peptide mRNAs in the hypothalamus, as evaluated by real-time quantitative PCR, were not different in respect to vehicle treated rats. Moreover, ghrelin/obestatin prepropeptide gene expression in the hypothalamus was not affected by obestatin treatment. In hypothalamic synaptosomes perfused with obestatin (1-100 nM), we found a dose-dependent inhibition of depolarization-induced dopamine release, while norepinephrine and serotonin releases were not modified by obestatin treatment. When ghrelin (1 nM) and obestatin (1 nM) were co-perfused, we observed that ghrelin reversed obestatin-induced inhibition of dopamine release, and obestatin was able to block ghrelin-induced inhibition of serotonin release. We can conclude that obestatin plays an anorectic role in the hypothalamus which could be partially mediated by the acute inhibition of dopamine release, with the possible involvement of antagonism of the hypothalamic serotonin inhibitory effects of ghrelin.
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Affiliation(s)
- Luigi Brunetti
- Department of Drug Sciences, School of Pharmacy, G. d'Annunzio University, via dei Vestini, Chieti, Italy
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Chen CY, Asakawa A, Fujimiya M, Lee SD, Inui A. Ghrelin gene products and the regulation of food intake and gut motility. Pharmacol Rev 2010; 61:430-81. [PMID: 20038570 DOI: 10.1124/pr.109.001958] [Citation(s) in RCA: 161] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A breakthrough using "reverse pharmacology" identified and characterized acyl ghrelin from the stomach as the endogenous cognate ligand for the growth hormone (GH) secretagogue receptor (GHS-R) 1a. The unique post-translational modification of O-n-octanoylation at serine 3 is the first in peptide discovery history and is essential for GH-releasing ability. Des-acyl ghrelin, lacking O-n-octanoylation at serine 3, is also produced in the stomach and remains the major molecular form secreted into the circulation. The third ghrelin gene product, obestatin, a novel 23-amino acid peptide identified from rat stomach, was found by comparative genomic analysis. Three ghrelin gene products actively participate in modulating appetite, adipogenesis, gut motility, glucose metabolism, cell proliferation, immune, sleep, memory, anxiety, cognition, and stress. Knockdown or knockout of acyl ghrelin and/or GHS-R1a, and overexpression of des-acyl ghrelin show benefits in the therapy of obesity and metabolic syndrome. By contrast, agonism of acyl ghrelin and/or GHS-R1a could combat human anorexia-cachexia, including anorexia nervosa, chronic heart failure, chronic obstructive pulmonary disease, liver cirrhosis, chronic kidney disease, burn, and postsurgery recovery, as well as restore gut dysmotility, such as diabetic or neurogenic gastroparesis, and postoperative ileus. The ghrelin acyl-modifying enzyme, ghrelin O-Acyltransferase (GOAT), which attaches octanoate to serine-3 of ghrelin, has been identified and characterized also from the stomach. To date, ghrelin is the only protein to be octanylated, and inhibition of GOAT may have effects only on the stomach and is unlikely to affect the synthesis of other proteins. GOAT may provide a critical molecular target in developing novel therapeutics for obesity and type 2 diabetes.
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Affiliation(s)
- Chih-Yen Chen
- Faculty of Medicine, National Yang-Ming University School of Medicine, Taipei, Japan
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Stengel A, Goebel M, Wang L, Taché Y. Ghrelin, des-acyl ghrelin and nesfatin-1 in gastric X/A-like cells: role as regulators of food intake and body weight. Peptides 2010; 31:357-69. [PMID: 19944123 PMCID: PMC3166546 DOI: 10.1016/j.peptides.2009.11.019] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 11/12/2009] [Accepted: 11/16/2009] [Indexed: 02/07/2023]
Abstract
Numerous peptides released from endocrine cells in the intestinal mucosa were established early on to be involved in the physiological regulation of food intake with a prominent role in termination of food ingestion when nutrients pass along the intestinal tract. Recently, peptides released from X/A-like endocrine cells of the gastric oxyntic mucosa were recognized as additional key players in the regulation of feeding and energy expenditure. Gastric X/A-like cells release the octanoylated peptide, ghrelin, the only known peripherally produced hormone stimulating food intake through interaction with growth hormone secretagogue 1a receptor (GHS-R1a). Additionally, non-octanoylated (des-acyl) ghrelin present in the circulation at higher levels than ghrelin is currently discussed as potential modulator of food intake by opposing ghrelin's action independent from GHS-R1a although the functional significance remains to be established. Obestatin, a ghrelin-associated peptide was initially reported as anorexigenic modulator of ghrelin's orexigenic action. However, subsequent reports did not support this contention. Interesting is the recent identification of nesfatin-1, a peptide derived from the nucleobindin2 gene prominently expressed in gastric X/A-like cells in different vesicles than ghrelin. Circulating nesfatin-1 levels vary with metabolic state and peripheral or central injection inhibits dark phase feeding in rodents. Overall, these data point to an important role of gastric X/A-like cells in food intake regulation through the expression of the orexigenic peptide ghrelin along with des-acyl ghrelin and nesfatin-1 capable of reducing food intake upon exogenous injection although their mechanisms of action and functional significance remain to be established.
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Affiliation(s)
- Andreas Stengel
- CURE: Digestive Diseases Research Center and Neurobiology of Stress, Digestive Diseases Division, David Geffen School of Medicine at University of California Los Angeles and Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA.
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Svenson J, Vergote V, Karstad R, Burvenich C, Svendsen JS, De Spiegeleer B. Metabolic Fate of Lactoferricin-Based Antimicrobial Peptides: Effect of Truncation and Incorporation of Amino Acid Analogs on the In Vitro Metabolic Stability. J Pharmacol Exp Ther 2009; 332:1032-9. [DOI: 10.1124/jpet.109.162826] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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