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Sanger GJ. Why is motilin active in some studies with mice, rats, and guinea pigs, but not in others? Implications for functional variability among rodents. Pharmacol Res Perspect 2022; 10:e00900. [PMID: 35191209 PMCID: PMC8860775 DOI: 10.1002/prp2.900] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 11/19/2021] [Indexed: 11/17/2022] Open
Abstract
The gastrointestinal (GI) hormone motilin helps control human stomach movements during hunger and promotes hunger. Although widely present among mammals, it is generally accepted that in rodents the genes for motilin and/or its receptor have undergone pseudonymization, so exogenous motilin cannot function. However, several publications describe functions of low concentrations of motilin, usually within the GI tract and CNS of mice, rats, and guinea pigs. These animals were from institute-held stocks, simply described with stock names (e.g., "Sprague-Dawley") or were inbred strains. It is speculated that variation in source/type of animal introduces genetic variations to promote motilin-sensitive pathways. Perhaps, in some populations, motilin receptors exist, or a different functionally-active receptor has a good affinity for motilin (indicating evolutionary pressures to retain motilin functions). The ghrelin receptor has the closest sequence homology, yet in non-rodents the receptors have a poor affinity for each other's cognate ligand. In rodents, ghrelin may substitute for certain GI functions of motilin, but no good evidence suggests rodent ghrelin receptors are highly responsive to motilin. It remains unknown if motilin has functional relationships with additional bioactive molecules formed from the ghrelin and motilin genes, or if a 5-TM motilin receptor has influence in rodents (e.g., to dimerize with GPCRs and create different pharmacological profiles). Is the absence/presence of responses to motilin in rodents' characteristic for systems undergoing gene pseudonymization? What are the consequences of rodent supplier-dependent variations in motilin sensitivity (or other ligands for receptors undergoing pseudonymization) on gross physiological functions? These are important questions for understanding animal variation.
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Affiliation(s)
- Gareth J. Sanger
- Blizard Institute and the National Centre for Bowel ResearchBarts and The London School of Medicine and DentistryQueen Mary University of LondonLondonUnited Kingdom
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Villarreal D, Pradhan G, Zhou Y, Xue B, Sun Y. Diverse and Complementary Effects of Ghrelin and Obestatin. Biomolecules 2022; 12:biom12040517. [PMID: 35454106 PMCID: PMC9028691 DOI: 10.3390/biom12040517] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 03/21/2022] [Accepted: 03/25/2022] [Indexed: 02/06/2023] Open
Abstract
Ghrelin and obestatin are two “sibling proteins” encoded by the same preproghrelin gene but possess an array of diverse and complex functions. While there are ample literature documenting ghrelin’s functions, the roles of obestatin are less clear and controversial. Ghrelin and obestatin have been perceived to be antagonistic initially; however, recent studies challenge this dogma. While they have opposing effects in some systems, they function synergistically in other systems, with many functions remaining debatable. In this review, we discuss their functional relationship under three “C” categories, namely complex, complementary, and contradictory. Their functions in food intake, weight regulation, hydration, gastrointestinal motility, inflammation, and insulin secretion are complex. Their functions in pancreatic beta cells, cardiovascular, muscle, neuroprotection, cancer, and digestive system are complementary. Their functions in white adipose tissue, thermogenesis, and sleep regulation are contradictory. Overall, this review accumulates the multifaceted functions of ghrelin and obestatin under both physiological and pathological conditions, with the intent of contributing to a better understanding of these two important gut hormones.
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Affiliation(s)
- Daniel Villarreal
- Department of Nutrition, Texas A & M University, College Station, TX 77843, USA;
| | - Geetali Pradhan
- USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA;
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yu Zhou
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao 266071, China;
| | - Bingzhong Xue
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA;
| | - Yuxiang Sun
- Department of Nutrition, Texas A & M University, College Station, TX 77843, USA;
- USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA;
- Correspondence: ; Tel.: +1-979-862-9143
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Neurohormonal Changes in the Gut–Brain Axis and Underlying Neuroendocrine Mechanisms following Bariatric Surgery. Int J Mol Sci 2022; 23:ijms23063339. [PMID: 35328759 PMCID: PMC8954280 DOI: 10.3390/ijms23063339] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/15/2022] [Accepted: 03/16/2022] [Indexed: 02/05/2023] Open
Abstract
Obesity is a complex, multifactorial disease that is a major public health issue worldwide. Currently approved anti-obesity medications and lifestyle interventions lack the efficacy and durability needed to combat obesity, especially in individuals with more severe forms or coexisting metabolic disorders, such as poorly controlled type 2 diabetes. Bariatric surgery is considered an effective therapeutic modality with sustained weight loss and metabolic benefits. Numerous genetic and environmental factors have been associated with the pathogenesis of obesity, while cumulative evidence has highlighted the gut–brain axis as a complex bidirectional communication axis that plays a crucial role in energy homeostasis. This has led to increased research on the roles of neuroendocrine signaling pathways and various gastrointestinal peptides as key mediators of the beneficial effects following weight-loss surgery. The accumulate evidence suggests that the development of gut-peptide-based agents can mimic the effects of bariatric surgery and thus is a highly promising treatment strategy that could be explored in future research. This article aims to elucidate the potential underlying neuroendocrine mechanisms of the gut–brain axis and comprehensively review the observed changes of gut hormones associated with bariatric surgery. Moreover, the emerging role of post-bariatric gut microbiota modulation is briefly discussed.
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Słupecka-Ziemilska M, Szczurek P, Boryczka M, Gajewska M, Wychowański P, Kuwahara A, Kato I, Dzięgelewska Ż, Woliński J. The effects of intra-stomach obestatin administration on intestinal contractility in neonatal piglets fed milk formula. PLoS One 2020; 15:e0230190. [PMID: 32203550 PMCID: PMC7089538 DOI: 10.1371/journal.pone.0230190] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Accepted: 02/24/2020] [Indexed: 12/03/2022] Open
Abstract
A 23-amino acid peptide named obestatin is derived from the ghrelin gene. The aim of the experiment was to study the effects of enteral obestatin administration for a 6-day period on intestinal contractility in piglets fed milk formula. Pigs were treated with 0.9% NaCl (group C) or varying doses of obestatin: 2 μg/kg body weight (BW) (group O2), 10 μg/kg BW (O10) or 15 μg/kg BW (O15) every 8 hours via a stomach tube. Blood was sampled for assessment of obestatin concentration. Duodenal and middle jejunum whole-thickness preparations were studied in an organ bath for isometric recording under electric field stimulation (EFS) and increasing doses of acetylcholine (ACh), and in the presence of atropine and tetrodotoxin (TTX). Additionally, the measurement of intestinal muscularis layer and the immunodetection of Muscarinic Acetylcholine Receptors (M1 and M2) were performed. In comparison to C animals, the obestatin concentration in blood plasma was significantly increased in groups O10 and O15. In both studied intestinal segments, significant increases in the frequency and amplitude of spontaneous contractions were observed in O15 and C groups. In the duodenum and middle jejunum significant differences in responsiveness to EFS (0.5, 5 and 50 Hz) were observed between the groups. The addition of 10−4 M ACh to the duodenum significantly increased the responsiveness in tissues. In contrast, in the middle jejunum a significant increase in the amplitude of contraction was observed after the addition of 10−9 and 10−6 M ACh (groups O15 and O10, respectively). Pretreatment with atropine and TTX resulted in a significant decrease in the responsiveness of the intestinal preparations from all groups, in both studied segments. The increased contractility was not dependent on the expression of muscarinic receptors. Results indicate the importance of enteral obestatin administration in the regulation of intestinal contractility in neonatal piglets.
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Affiliation(s)
- Monika Słupecka-Ziemilska
- Department of Animal Physiology, Polish Academy of Sciences, The Kielanowski Institute of Animal Physiology and Nutrition, Jabłonna, Poland
| | - Paulina Szczurek
- Department of Animal Nutrition and Feed Sciences, National Research Institute of Animal Production, Balice, Poland
| | - Maria Boryczka
- Department of Animal Physiology, Polish Academy of Sciences, The Kielanowski Institute of Animal Physiology and Nutrition, Jabłonna, Poland
| | - Małgorzata Gajewska
- Department of Physiological Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Warsaw, Poland
| | - Piotr Wychowański
- Department of Dental Surgery, Medical University of Warsaw, Warsaw, Poland
| | - Atsukazu Kuwahara
- Laboratory of Physiology, Institute for Environmental Sciences & Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan
| | - Ikuo Kato
- Department of Medical Biochemistry, Kobe Pharmaceutical University, Kobe, Japan
| | - Żaneta Dzięgelewska
- Department of Physiological Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Warsaw, Poland
| | - Jarosław Woliński
- Department of Animal Physiology, Polish Academy of Sciences, The Kielanowski Institute of Animal Physiology and Nutrition, Jabłonna, Poland
- * E-mail:
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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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Słupecka M, Grzesiak P, Kwiatkowski J, Gajewska M, Kuwahara A, Kato I, Woliński J. The influence of enteral obestatin administration to suckling rats on intestinal contractility. Gen Comp Endocrinol 2017; 248:69-78. [PMID: 28212895 DOI: 10.1016/j.ygcen.2017.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Revised: 01/24/2017] [Accepted: 02/13/2017] [Indexed: 12/13/2022]
Abstract
This study investigated the effect of enteral administration of obestatin on the contractility of whole-thickness preparations of duodenum and middle jejunum, as well as on the morphology of the enteric nervous system (ENS). Suckling rats were assigned to 3 groups (n=12) treated with: C-saline solution; LO-obestatin (125nmol/kgb.wt); HO-obestatin (250nmol/kgb.wt). Saline solution or obestatin were administered twice daily, from the 14th to the 21st day of life. Sections were studied in an organ bath, for isometric recording in the presence of acetylocholine (ACh), atropine (ATR) and tetradotoxin (TTX). Thickness of intestinal muscularis layer, the number of interstitial cells of Cajal (ICC) were measured in the paraffin sections. The immunodetection of Muscarinic Acetylocholine Receptor 2 (M2 receptor) was performed in the intestinal segments. In both intestinal segments HO treatment decreased the amplitude of spontaneous contraction compared to that observed in the C group. In the middle jejunum, the LO treatment also decreased the amplitude. TTX and ATR had no effect on amplitude of spontaneous contraction in the jejunum of LO and HO-treated animals. Compared to the C group, duodenal sections from HO animals and middle jejunum sections from LO and HO groups displayed a lower amplitude in response to ACh and EFS evoked contraction. An increase in the thickness of the muscularis layer was observed in the duodenum of LO and HO groups whereas the number ICC did not change significantly after treatment with obestatin. Moreover, the enteral administration of obestatin did not effect significantly on the cytoplasmic expression of M2 receptor in the jejunum. Our study demonstrated that enteral administration of obestatin to suckling rats influences small intestine contractility in the segment specific manner.
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Affiliation(s)
- M Słupecka
- Department of Animal Physiology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Jabłonna, Poland.
| | - P Grzesiak
- Department of Animal Physiology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Jabłonna, Poland
| | - J Kwiatkowski
- Department of Animal Physiology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Jabłonna, Poland
| | - M Gajewska
- Department of Physiological Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Warsaw, Poland
| | - A Kuwahara
- Laboratory of Physiology, Institute for Environmental Sciences and Graduate School of Nutritional and Enviromental Science, University of Shizuoka, Japan
| | - I Kato
- Department of Medical Biochemistry, Kobe Pharmaceutical University, Japan
| | - J Woliński
- Department of Animal Physiology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Jabłonna, Poland
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7
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Xing YX, Yang L, Kuang HY, Gao XY, Liu HL. Function of obestatin in the digestive system. Nutrition 2017; 34:21-28. [DOI: 10.1016/j.nut.2016.08.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 04/18/2016] [Accepted: 08/29/2016] [Indexed: 02/07/2023]
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Nagaraj S, Manjappara UV. Studies on the influence of CCK-8 on the ability of obestatin to reduce food intake, gain in body weight and related lipid parameters. Biochimie 2016; 125:126-30. [DOI: 10.1016/j.biochi.2016.03.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Accepted: 03/21/2016] [Indexed: 10/22/2022]
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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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Yamawaki H, Futagami S, Shimpuku M, Shindo T, Maruki Y, Nagoya H, Kodaka Y, Sato H, Gudis K, Kawagoe T, Sakamoto C. Leu72Met408 Polymorphism of the Ghrelin Gene Is Associated With Early Phase of Gastric Emptying in the Patients With Functional Dyspepsia in Japan. J Neurogastroenterol Motil 2015; 21:93-102. [PMID: 25540946 PMCID: PMC4288091 DOI: 10.5056/jnm14086] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Revised: 09/11/2014] [Accepted: 09/13/2014] [Indexed: 12/11/2022] Open
Abstract
Background/Aims There are no available data about the relationship between ghrelin gene genotypes and early phase of gastric emptying in functional dyspepsia (FD) as defined by Rome III classification. Methods We enrolled 74 patients presenting with typical symptoms of FD and 64 healthy volunteers. Gastric motility was evaluated using the 13C-acetate breath test. We used Rome III criteria to evaluate upper abdominal symptoms and self-rating questionnaires for depression (SRQ-D) scores to determine status of depression. The Arg51Gln (346G>A), preproghrelin (3056T>C), Leu72Met (408C>A), Gln90Leu (3412T>A) and G-protein β3 (825C>T) polymorphisms were analyzed in the DNA from blood samples of enrolled subjects. Genotyping was performed by polymerase chain reaction. Results There was a significant relationship between the Gln90Leu3412 genotype and SRQ-D score in FD patients (P = 0.009). Area under the curve at 15 minutes (AUC15) value was significantly associated with the Leu72Met408 genotype (P = 0.015) but not with entire gastric emptying. Conclusions The Leu72Met (408C>A) single nucleotide polymorphism was significantly associated with early phase of gastric emptying in FD patients. Further studies will be necessary to clarify the association between ghrelin gene single nucleotide polymorphisms and early phase of gastric emptying in FD patients.
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Affiliation(s)
- Hiroshi Yamawaki
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School, Sendagi, Tokyo, Japan
| | - Seiji Futagami
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School, Sendagi, Tokyo, Japan
| | - Mayumi Shimpuku
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School, Sendagi, Tokyo, Japan
| | - Tomotaka Shindo
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School, Sendagi, Tokyo, Japan
| | - Yuuta Maruki
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School, Sendagi, Tokyo, Japan
| | - Hiroyuki Nagoya
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School, Sendagi, Tokyo, Japan
| | - Yasuhiro Kodaka
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School, Sendagi, Tokyo, Japan
| | - Hitomi Sato
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School, Sendagi, Tokyo, Japan
| | - Katya Gudis
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School, Sendagi, Tokyo, Japan
| | - Tetsuro Kawagoe
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School, Sendagi, Tokyo, Japan
| | - Choitsu Sakamoto
- Division of Gastroenterology, Department of Internal Medicine, Nippon Medical School, Sendagi, Tokyo, Japan
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Słupecka M, Pierzynowski SG, Kuwahara A, Kato I, Woliński J. Age-dependent effect of obestatin on intestinal contractility in Wistar rats. Gen Comp Endocrinol 2014; 208:109-15. [PMID: 25193331 DOI: 10.1016/j.ygcen.2014.08.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 05/28/2014] [Accepted: 08/10/2014] [Indexed: 11/26/2022]
Abstract
Obestatin is a 23-amino acid peptide encoded by the ghrelin gene. We have investigated the effect of obestatin on intestinal contractility in rats ranging from the suckling period till adolescence. Duodenal and middle jejunum whole-thickness preparations from neonatal and adult rats were studied in an organ bath, for isometric recording under treatment with obestatin (1μmolL(-1)) in the presence of acetylocholine (ACh), atropine and tetradotoxin (TTX). Both the EFS and ACh-stimulated contractile response, as well as spontaneous contractile activity is age-dependent and specific for the segment of jejunum. Except for the middle jejunum of 7day old rats, treatment with obestatin caused a significant TTX-sensitive increase in the amplitude of EFS-stimulated off-contraction of both intestinal segments studied. Following injection of obestatin, the amplitude of spontaneous contraction in the duodenum increased in 7day old rats. In the middle jejunum, treatment with obestatin significantly increased both the amplitude and frequency of spontaneous contraction in rats till the 28th day of life, whereas in adult rats the observed effect of obestatin was the opposite (P<0.001 and P<0.0001, respectively). The effects of treatment with obestatin on stimulation with increasing doses of ACh were only observed in the preparations from suckling rats. ACh-stimulated contractility in the duodenum was decreased while in the middle jejunum the observed effect was opposite. These results indicate the importance of peripheral obestatin in the cholinergic control of intestinal contractility in both neonatal and adult rats.
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Affiliation(s)
- M Słupecka
- Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Jabłonna, Poland.
| | - S G Pierzynowski
- Department of Biology, Lund University, Lund, Sweden; Department of Medical Biology, Institute of Agricultural Medicine, Lublin, Poland
| | - A Kuwahara
- Laboratory of Physiology, Institute for Environmental Sciences & Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan
| | - I Kato
- Department of Bioorganic Chemistry, Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa, Japan
| | - J Woliński
- Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Jabłonna, Poland
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Prodam F, Filigheddu N. Ghrelin gene products in acute and chronic inflammation. Arch Immunol Ther Exp (Warsz) 2014; 62:369-84. [PMID: 24728531 DOI: 10.1007/s00005-014-0287-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Accepted: 03/21/2014] [Indexed: 12/27/2022]
Abstract
Ghrelin gene products--the peptides ghrelin, unacylated ghrelin, and obestatin--have several actions on the immune system, opening new perspectives within neuroendocrinology, metabolism and inflammation. The aim of this review is to summarize the available evidence regarding the less known role of these peptides in the machinery of inflammation and autoimmunity, outlining some of their most promising therapeutic applications.
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Affiliation(s)
- Flavia Prodam
- Departmant of Health Sciences, Università del Piemonte Orientale "Amedeo Avogadro", Novara, Italy
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13
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Gahete MD, Rincón-Fernández D, Villa-Osaba A, Hormaechea-Agulla D, Ibáñez-Costa A, Martínez-Fuentes AJ, Gracia-Navarro F, Castaño JP, Luque RM. Ghrelin gene products, receptors, and GOAT enzyme: biological and pathophysiological insight. J Endocrinol 2014; 220:R1-24. [PMID: 24194510 DOI: 10.1530/joe-13-0391] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ghrelin is a 28-amino acid acylated hormone, highly expressed in the stomach, which binds to its cognate receptor (GHSR1a) to regulate a plethora of relevant biological processes, including food intake, energy balance, hormonal secretions, learning, inflammation, etc. However, ghrelin is, in fact, the most notorious component of a complex, intricate regulatory system comprised of a growing number of alternative peptides (e.g. obestatin, unacylated ghrelin, and In1-ghrelin, etc.), known (GHSRs) and, necessarily unknown receptors, as well as modifying enzymes (e.g. ghrelin-O-acyl-transferase), which interact among them as well as with other regulatory systems in order to tightly modulate key (patho)-physiological processes. This multiplicity of functions and versatility of the ghrelin system arise from a dual, genetic and functional, complexity. Importantly, a growing body of evidence suggests that dysregulation in some of the components of the ghrelin system can lead to or influence the development and/or progression of highly concerning pathologies such as endocrine-related tumors, inflammatory/cardiovascular diseases, and neurodegeneration, wherein these altered components could be used as diagnostic, prognostic, or therapeutic targets. In this context, the aim of this review is to integrate and comprehensively analyze the multiple components and functions of the ghrelin system described to date in order to define and understand its biological and (patho)-physiological significance.
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Affiliation(s)
- Manuel D Gahete
- Department of Cell Biology, Physiology and Immunology, Campus Universitario de Rabanales, Edificio Severo Ochoa (C6), Planta 3, University of Córdoba, 14014-Córdoba; Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), University of Córdoba; Reina Sofia University Hospital, Córdoba; and CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Córdoba, Spain
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Squecco R, Garella R, Francini F, Baccari MC. Influence of obestatin on the gastric longitudinal smooth muscle from mice: mechanical and electrophysiological studies. Am J Physiol Gastrointest Liver Physiol 2013; 305:G628-37. [PMID: 23989009 DOI: 10.1152/ajpgi.00059.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Obestatin is a hormone released from the stomach deriving from the same peptide precursor as ghrelin. It is known to act as an anorectic hormone decreasing food intake, but contrasting results have been reported about the effects of obestatin on gastrointestinal motility. The aim of the present study was to investigate whether this peptide may act on the gastric longitudinal smooth muscle by using a combined mechanical and electrophysiological approach. When fundal strips from mice were mounted in organ baths for isometric recording of the mechanical activity, obestatin caused a tetrodotoxin-insensitive decrease of the basal tension and a reduction in amplitude of the neurally induced cholinergic contractile responses, even in the presence of the nitric oxide synthesis inhibitor N(G)-nitro-l-arginine. Obestatin reduced the amplitude of the response to the ganglionic stimulating agent dimethylphenyl piperazinium iodide but did not influence that to methacholine. In nonadrenergic, noncholinergic conditions, obestatin still decreased the basal tension of the preparations without influencing the neurally induced relaxant responses. For comparison, in circular fundal strips, obestatin had no effects. Notably, in the longitudinal antral ones, obestatin only caused a decrease of the basal tension. Electrophysiological experiments, performed by a single microelectrode inserted in a gastric longitudinal smooth muscle cell, showed that obestatin had similar effects in fundal and antral preparations: it decreased the resting specific membrane conductance, inhibited Ca(2+) currents, and positively shifted their voltage threshold of activation. In conclusion, the present results indicate that obestatin influences gastric smooth muscle exerting site-specific effects.
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Affiliation(s)
- Roberta Squecco
- Dipartimento di Medicina Sperimentale e Clinica, Sezione di Scienze Fisiologiche, Università degli Studi, Firenze, Viale Morgagni 63, 50134, Italy.
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15
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Ren G, He Z, Cong P, Yu J, Qin Y, Chen Y, Liu X. Effect of TAT-obestatin on proliferation, differentiation, apoptosis and lipolysis in 3T3-L1 preadipocytes. J Pept Sci 2013; 19:684-91. [PMID: 24106000 DOI: 10.1002/psc.2550] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 07/17/2013] [Accepted: 08/13/2013] [Indexed: 12/11/2022]
Abstract
It has been reported that obestatin regulates adipocyte metabolism via receptors on the cell surface. We wondered whether obestatin can interact with intracellular components that activated signalling pathways in adipocytes. Because obestatin (human) only presents one lysine (at position 10), which cannot penetrate the cell membrane, therefore, we used a cell-permeable peptide TAT (49-57) as a vector to carry obestatin across the cell membrane. The goal of this study was to further understand the function of obestatin after penetrating the cell membrane. Our results showed that TAT-obestatin could cross the 3T3-L1 cell membrane in the absence of cytotoxicity. TAT-obestatin showed no effect on the proliferation of 3T3-L1 preadipocytes. In contrast, obestatin significantly stimulated proliferation at a dose of 10(-11) M and 10(-13) M. In addition, TAT-obestatin demonstrated a more potent inhibitory effect on cell apoptosis induced by serum starvation than that of obestatin. During the progress of adipocyte differentiation, TAT-obestatin and obestatin had no effect on adipogenesis. In the lipolysis assay, TAT-obestatin significantly increased glycerol and free fatty acid release from 3T3-L1 adipocytes after 3 h treatment but showed no significant effect on lipolysis after 24 h and 48 h of treatment. In contrast, obestatin (10(-7) M) had no effect on glycerol release after 3, 24 and 48 h of treatment. The difference between the effect of TAT-obestatin and obestatin on adipocytes metabolism indicated that TAT-obestatin may trigger intracellular signalling as well as signalling at the cell membrane.
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Affiliation(s)
- Guangcai Ren
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510006, China
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16
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Yagi T, Asakawa A, Ueda H, Miyawaki S, Inui A. The role of ghrelin in patients with functional dyspepsia and its potential clinical relevance (Review). Int J Mol Med 2013; 32:523-31. [PMID: 23778458 DOI: 10.3892/ijmm.2013.1418] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 06/03/2013] [Indexed: 12/31/2022] Open
Abstract
Functional dyspepsia (FD) is a functional gastrointestinal disorder (FGID). According to the Rome III consensus, FD is divided into 2 subgroups: epigastric pain syndrome (EPS) and postprandial distress syndrome (PDS). Although multiple mechanisms of FD pathogenesis have been suggested, its underlying etiology and pharmacological therapy remain unclear. Ghrelin is a gut-derived peptide found in the stomach. It plays a role in the regulation of gastric motility and appetite. The ghrelin gene encodes 3 molecular forms, acyl ghrelin, des-acyl ghrelin and obestatin. Acyl ghrelin acts as an endogenous ligand for growth hormone secretagogue receptor; furthermore, it is orexigenic, with effects on food intake, energy homeostasis and gastrointestinal motility. Des-acyl ghrelin exerts an opposite effect to acyl ghrelin. Obestatin exerts an inhibitory effect on the motor activity of the antrum and duodenum in fed animals. These peptides exert differential effects on gut motility and food intake. The therapeutic potential of ghrelin has attracted attention due to its varied bioactivities. Certain studies have shown that total ghrelin levels are significantly lower in patients with FD compared with healthy volunteers and that the acyl ghrelin levels of patients with FD are higher compared with healthy volunteers. However, a recent study demonstrated that acyl ghrelin levels in patients with PDS were lower compared with healthy volunteers; the association between FD and other ghrelin family gene products also remains unclear. Although certain studies have demonstrated the beneficial effects of acyl ghrelin administration and its agonist in patients with FD, only a few clinical reports exist. Further studies are required in order to examine the effects of ghrelin on FD.
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Affiliation(s)
- Takakazu Yagi
- Department of Orthodontics and Dentofacial Orthopedics, Medical and Dental Hospital, Kagoshima University, Kagoshima 890-8544, Japan
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17
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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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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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Agnew AJ, Robinson E, McVicar CM, Harvey AP, Ali IHA, Lindsay JE, McDonald DM, Green BD, Grieve DJ. The gastrointestinal peptide obestatin induces vascular relaxation via specific activation of endothelium-dependent NO signalling. Br J Pharmacol 2012; 166:327-38. [PMID: 22035179 DOI: 10.1111/j.1476-5381.2011.01761.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND AND PURPOSE Obestatin is a recently discovered gastrointestinal peptide with established metabolic actions, which is linked to diabetes and may exert cardiovascular benefits. Here we aimed to investigate the specific effects of obestatin on vascular relaxation. EXPERIMENTAL APPROACH Cumulative relaxation responses to obestatin peptides were assessed in rat isolated aorta and mesenteric artery (n≥ 8) in the presence and absence of selective inhibitors. Complementary studies were performed in cultured bovine aortic endothelial cells (BAEC). KEY RESULTS Obestatin peptides elicited concentration-dependent relaxation in both aorta and mesenteric artery. Responses to full-length obestatin(1-23) were greater than those to obestatin(1-10) and obestatin(11-23). Obestatin(1-23)-induced relaxation was attenuated by endothelial denudation, l-NAME (NOS inhibitor), high extracellular K(+) , GDP-β-S (G-protein inhibitor), MDL-12,330A (adenylate cyclase inhibitor), wortmannin (PI3K inhibitor), KN-93 (CaMKII inhibitor), ODQ (guanylate cyclase inhibitor) and iberiotoxin (BK(Ca) blocker), suggesting that it is mediated by an endothelium-dependent NO signalling cascade involving an adenylate cyclase-linked GPCR, PI3K/PKB, Ca(2+) -dependent eNOS activation, soluble guanylate cyclase and modulation of vascular smooth muscle K(+) . Supporting data from BAEC indicated that nitrite production, intracellular Ca(2+) and PKB phosphorylation were increased after exposure to obestatin(1-23). Relaxations to obestatin(1-23) were unaltered by inhibitors of candidate endothelium-derived hyperpolarizing factors (EDHFs) and combined SK(Ca) /IK(Ca) blockade, suggesting that EDHF-mediated pathways were not involved. CONCLUSIONS AND IMPLICATIONS Obestatin produces significant vascular relaxation via specific activation of endothelium-dependent NO signalling. These actions may be important in normal regulation of vascular function and are clearly relevant to diabetes, a condition characterized by endothelial dysfunction and cardiovascular complications.
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Affiliation(s)
- Andrew J Agnew
- School of Biological Sciences, Queen's University Belfast, Belfast, UK
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20
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Abstract
The migrating motor complex (MMC) is a cyclic, recurring motility pattern that occurs in the stomach and small bowel during fasting; it is interrupted by feeding. The MMC is present in the gastrointestinal tract of many species, including humans. The complex can be subdivided into four phases, of which phase III is the most active, with a burst of contractions originating from the antrum or duodenum and migrating distally. Control of the MMC is complex. Phase III of the MMC with an antral origin can be induced in humans through intravenous administration of motilin, erythromycin or ghrelin, whereas administration of serotonin or somatostatin induces phase III activity with duodenal origin. The role of the vagus nerve in control of the MMC seems to be restricted to the stomach, as vagotomy abolishes the motor activity in the stomach, but leaves the periodic activity in the small bowel intact. The physiological role of the MMC is incompletely understood, but its absence has been associated with gastroparesis, intestinal pseudo-obstruction and small intestinal bacterial overgrowth. Measuring the motility of the gastrointestinal tract can be important for the diagnosis of gastrointestinal disorders. In this Review we summarize current knowledge of the MMC, especially its role in health and disease.
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21
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Fujimiya M, Ataka K, Asakawa A, Chen CY, Kato I, Inui A. Ghrelin, des-acyl ghrelin and obestatin on the gastrointestinal motility. Peptides 2011; 32:2348-51. [PMID: 21835213 DOI: 10.1016/j.peptides.2011.07.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 06/21/2011] [Accepted: 07/22/2011] [Indexed: 12/11/2022]
Abstract
Ghrelin, des-acyl ghrelin and obestatin are derived from a common prohormone, preproghrelin by posttranslational processing, originating from endocrine cells in the stomach. Ghrelin exerts stimulatory effects on the motility of antrum and duodenum in both fed and fasted state of animals. On the other hand, des-acyl ghrelin exerts inhibitory effects on the motility of antrum but not on the motility of duodenum in the fasted state of animals. Obestatin exerts inhibitory effects on the motility of antrum and duodenum in the fed state but not in the fasted state of animals. NPY Y2 and Y4 receptors in the brain may mediate the action of ghrelin, CRF type 2 receptor in the brain may mediate the action of des-acyl ghrelin, whereas CRF type 1 and type 2 receptors in the brain may mediate the action of obestatin.
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Affiliation(s)
- Mineko Fujimiya
- Department of Anatomy, Sapporo Medical University School of Medicine, Sapporo, Japan.
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22
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23
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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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24
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Qian Q, Chen W, Guo C, Wu W, Qian W, Li S. Xiao-Ban-Xia-Tang inhibits cisplatin-induced pica by down regulating obestatin in rats. JOURNAL OF ETHNOPHARMACOLOGY 2011; 135:186-193. [PMID: 21396996 DOI: 10.1016/j.jep.2011.03.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 02/22/2011] [Accepted: 03/03/2011] [Indexed: 05/30/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Xiao-Ban-Xia-Tang (XBXT), a traditional Chinese herbal medicine, has been used in China for more than 2000 years, and proved to be effective in various cases of vomiting in the clinic. OBJECTIVE To investigate the inhibitive effect of XBXT on cisplatin-induced pica behaviour and its effective mechanism on obestatin, CCK and CGRP in the pica model of rat. MATERIALS AND METHODS The inhibitive effect of XBXT was investigated in the pica model of rats induced by cisplatin (3mg kg(-1), i.p.) in 72h observation, the expression of obestatin in the area postrema and ileum was measured by immunohistochemistry and PCR, and the levels of CCK and CGRP in blood were measured by Elisa. RESULTS The weight of kaolin eaten in rats induced by cisplatin was significantly reduced by pretreatment with XBXT in a dose-dependent manner during the 0-24h and 24-72h periods (P<0.05). XBXT exhibited effective dose-dependent (P<0.05) inhibition on the increase of expression levels of obestatin in both the ileum and area postrema, and markedly suppressed the increase levels of CCK and CGRP in blood induced by cisplatin in a dose-dependent manner (P<0.05). CONCLUSIONS XBXT has good activity against cisplatin-induced eating kaolin in rats possibly by inhibiting central or peripheral increase of obestatin, or the levels of CCK and CGRP in blood.
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Affiliation(s)
- Qiuhai Qian
- Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan 250011, Shandong, China.
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25
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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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26
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Sanger GJ, Hellström PM, Näslund E. The hungry stomach: physiology, disease, and drug development opportunities. Front Pharmacol 2011; 1:145. [PMID: 21927604 PMCID: PMC3174087 DOI: 10.3389/fphar.2010.00145] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 12/22/2010] [Indexed: 01/28/2023] Open
Abstract
During hunger, a series of high-amplitude contractions of the stomach and small intestine (phase III), which form part of a cycle of quiescence and contractions (known as the migrating motor complex, MMC), play a "housekeeping" role prior to the next meal, and may contribute toward the development of hunger. Several gastrointestinal (GI) hormones are associated with phase III MMC activity, but currently the most prominent is motilin, thought to at least partly mediate phase III contractions of the gastric MMC. Additional GI endocrine and neuronal systems play even more powerful roles in the development of hunger. In particular, the ghrelin-precursor gene is proving to have a complex physiology, giving rise to three different products: ghrelin itself, which is formed from a post-translational modification of des-acyl-ghrelin, and obestatin. The receptors acted on by des-acyl-ghrelin and by obestatin are currently unknown but both these peptides seem able to exert actions which oppose that of ghrelin, either indirectly or directly. An increased understanding of the actions of these peptides is helping to unravel a number of different eating disorders and providing opportunities for the discovery of new drugs to regulate dysfunctional gastric behaviors and appetite. To date, ghrelin and motilin receptor agonists and antagonists have been described. The most advanced are compounds which activate the ghrelin and motilin receptors which are being progressed for disorders associated with gastric hypomotility.
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Affiliation(s)
- Gareth J. Sanger
- Wingate Institute of Neurogastroenterology, Barts and The London School of Medicine and Dentistry, Queen Mary University of LondonLondon, UK
| | - Per M. Hellström
- Department of Medical Sciences, Uppsala UniversityUppsala, Sweden
| | - Erik Näslund
- Division of Surgery, Department of Clinical Sciences, Danderyd Hospital, Karolinska InstitutetStockholm, Sweden
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27
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Balagopal PB, Gidding SS, Buckloh LM, Yarandi HN, Sylvester JE, George DE, Funanage VL. Changes in circulating satiety hormones in obese children: a randomized controlled physical activity-based intervention study. Obesity (Silver Spring) 2010; 18:1747-53. [PMID: 20094040 DOI: 10.1038/oby.2009.498] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The aims of this study are to examine in children: (i) obesity-related alterations in satiety factors such as leptin, ghrelin, and obestatin; (ii) the link between satiety factors and cardiometabolic risk factors; and (iii) the impact of a physical activity-based lifestyle intervention on the levels of these satiety factors in the obese. We studied a total of 21 adolescents (BMI percentile, 99.0 +/- 0.6 for 15 obese and 56.2 +/- 1.1 for 6 lean). The obese subjects underwent a 3-month randomized controlled physical activity-based lifestyle intervention. Leptin, soluble leptin receptor (sOB-R), ghrelin, and obestatin levels were determined as the primary outcome measures. Other markers of cardiometabolic disease such as inflammation and insulin resistance were also determined. Body composition was measured by dual-energy X-ray absorptiometry. The concentrations of ghrelin, obestatin, and sOB-R were significantly lower in the obese children compared to the lean controls, whereas that of leptin was higher (all P < 0.05). Although intervention led to a net increase in obestatin (P < 0.01) and no change in ghrelin levels, the balance between ghrelin and obestatin (ratio of ghrelin to obestatin, G/O) decreased (P < 0.02). Intervention reduced leptin and increased sOB-R (P < 0.01 for both). Significant associations between satiety factors and other cardiometabolic risk factors were also observed. Taken together, alterations in the levels of satiety factors are evident early in the clinical course of obesity, but physical activity-based lifestyle intervention either prevented their continued increase or normalized their levels. These beneficial effects appear to aid in the maintenance of body weight and reduction in cardiovascular risk.
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28
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Chen CY, Doong ML, Li CP, Liaw WJ, Lee HF, Chang FY, Lin HC, Lee SD. A novel simultaneous measurement method to assess the influence of intracerebroventricular obestatin on colonic motility and secretion in conscious rats. Peptides 2010; 31:1113-7. [PMID: 20338205 DOI: 10.1016/j.peptides.2010.03.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Revised: 03/17/2010] [Accepted: 03/17/2010] [Indexed: 12/14/2022]
Abstract
Obestatin, a novel putative 23-amino acid peptide, is derived from mammalian preproghrelin gene via a bioinformatics approach. Although obestatin regulates thirst, sleep, memory, anxiety, activates cortical neurons in the brain and stimulate proliferation of retinal pigment epithelial cells, there is no study to explore its central impacts on the lower gut motility and secretion. We investigated the influence of intracerebroventricular (ICV) injection of obestatin on rat colonic motor and secretory functions. Colonic transit time, fecal pellet output and fecal content were assessed in freely fed, conscious rats, which were implanted with ICV and colonic catheters chronically. Human/rat corticotropin-releasing factor (h/rCRF) was applied as a stimulatory inducer of colonic motility and secretion. ICV injection of obestatin (0.1, 0.3, 1.0 nmol/rat) did not modify the colonic transit time, whereas ICV injection of h/rCRF (0.3 nmol/rat) significantly shortened colonic transit time. ICV obestatin in any dose we tested did not affect the fecal pellet output, frequency of watery diarrhea, total fecal weight, fecal dried solid weight, or fecal fluid weight in the first hour post-injection, either. In contrast, ICV injection of h/rCRF effectively stimulated fecal pellet output, as well as increased total fecal weight, fecal dried solid weight and fecal fluid weight during the first hour post-injection, compared to ICV saline controls. In conclusion, using our novel simultaneous measurement method, acutely central administration of obestatin exhibits no influence on colonic motility and secretion in conscious rats.
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Affiliation(s)
- Chih-Yen Chen
- Faculty of Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan.
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29
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St-Pierre DH, Settanni F, Olivetti I, Gramaglia E, Tomelini M, Granata R, Prodam F, Benso A, Ghigo E, Broglio F. Circulating obestatin levels in normal and Type 2 diabetic subjects. J Endocrinol Invest 2010; 33:211-4. [PMID: 20503481 DOI: 10.1007/bf03345780] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND Obestatin has been discovered as a new product of the ghrelin gene. Its physiological actions are still a matter of debate, but it seems that this peptide is likely to be involved in the control of insulin secretion and action as well as of adipocyte function. It has been already shown that obestatin secretion in humans is negatively modulated by food intake. AIM To clarify obestatin secretion in normal subjects and in patients with Type 2 diabetes (T2D) in basal conditions and after a standardized meal. SUBJECTS/METHODS Five normal subjects and 5 T2D patients were studied during infusion of saline (iv for over 5 h from -120 to +180 min). A standardized lunch was served at 0 min. Obestatin, glucose, and insulin levels were assayed at -120, -90, -60, -45, -30, -15, 0, 15, 30, 45, 60, 90, 120, 150, and 180 min. RESULTS From -120 to 0 min, obestatin levels in normal and T2D subjects were similar (area under the curve: 32.3+/-5.6 pg/ml/min vs 31.1+/-1.0 pg/ml/min). After the meal, circulating obestatin levels underwent a clear decrease in normal subjects (0 min: 300.6+/-34.7 pg/ml vs nadir at 60 min: 161.8+/-29.4 pg/ml; p=0.002) but not in diabetic patients (0 min: 267.2+/-16.5 pg/ml vs nadir at 180 min: 226.0+/-10.5 pg/ml). CONCLUSION This study shows that normal and diabetic subjects display similar levels of circulating obestatin in fasting condition. However patients with T2D look refractory to the inhibitory effect of meal on obestatin secretion.
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Affiliation(s)
- D H St-Pierre
- Division of Endocrinology, Diabetology and Metabolism, Department of Internal Medicine, Molinette Hospital, University of Turin, Turin, Italy
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Ghrelin, des-acyl ghrelin, and obestatin: regulatory roles on the gastrointestinal motility. INTERNATIONAL JOURNAL OF PEPTIDES 2010; 2010. [PMID: 20721292 PMCID: PMC2915652 DOI: 10.1155/2010/305192] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Accepted: 12/22/2009] [Indexed: 12/16/2022]
Abstract
Ghrelin, des-acyl ghrelin, and obestatin are derived from a common prohormone, preproghrelin by posttranslational processing, originating from endocrine cells in the stomach. To examine the regulatory roles of these peptides, we applied the manometric measurement of gastrointestinal motility in freely moving conscious rat or mouse model. Ghrelin exerts stimulatory effects on the motility of antrum and duodenum in both fed and fasted state of animals. Des-acyl ghrelin exerts inhibitory effects on the motility of antrum but not on the motility of duodenum in the fasted state of animals. Obestatin exerts inhibitory effects on the motility of antrum and duodenum in the fed state but not in the fasted state of animals. NPY Y2 and Y4 receptors in the brain may mediate the action of ghrelin, CRF type 2 receptor in the brain may mediate the action of des-acyl ghrelin, whereas CRF type 1 and type 2 receptors in the brain may mediate the action of obestatin. Vagal afferent pathways might be involved in the action of ghrelin, but not involved in the action of des-acyl ghrelin, whereas vagal afferent pathways might be partially involved in the action of obestatin.
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31
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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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32
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Epelbaum J, Bedjaoui N, Dardennes R, Feng DD, Gardette R, Grouselle D, Loudes C, Simon A, Tolle V, Yang SK, Zizzari P. Role of the ghrelin/obestatin balance in the regulation of neuroendocrine circuits controlling body composition and energy homeostasis. Mol Cell Endocrinol 2010; 314:244-7. [PMID: 19733621 DOI: 10.1016/j.mce.2009.08.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Accepted: 08/30/2009] [Indexed: 11/16/2022]
Abstract
Ghrelin and obestatin are two peptides isolated from the gastrointestinal tract and encoded by the same preproghrelin gene. They convey to the central nervous system informations concerning the nutritional status and/or the energy stores. Ghrelin, mostly acting through the GH secretagogue receptor GHS-R, is a potent GH secretagogue, an orexigenic peptide and a long-term regulator of energy homeostasis. Obestatin was initially described for its anorexigenic effects and its binding to the G protein-coupled receptor 39 (GPR39). However, the role of obestatin is still controversial and the nature of the obestatin receptor remains an open question. This review is focussed on the possible implication of the ghrelin/obestatin system in psychiatric diseases with particular emphasis on eating disorders.
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Affiliation(s)
- Jacques Epelbaum
- Centre de Psychiatrie & Neurosciences, UMR 894 Inserm, Faculté de Médecine, Université Paris Descartes, Paris, France.
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33
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Xin X, Ren AJ, Zheng X, Qin YW, Zhao XX, Yuan WJ, Guo ZF. Disturbance of circulating ghrelin and obestatin in chronic heart failure patients especially in those with cachexia. Peptides 2009; 30:2281-5. [PMID: 19666068 DOI: 10.1016/j.peptides.2009.07.026] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 07/30/2009] [Accepted: 07/30/2009] [Indexed: 11/21/2022]
Abstract
Plasma ghrelin was elevated in chronic heart failure (CHF) patients with cachexia. Obestatin, a sibling of ghrelin, opposes several actions of ghrelin. We, therefore, investigated plasma obestatin and ghrelin levels in patients with CHF. Total plasma ghrelin and obestatin levels were measured in 65 patients with CHF (22 with cardiac cachexia) and 15 controls. Ghrelin levels were significantly higher in patients with cachexia (1237.8+/-47.9 pg/ml) than those without cachexia (P=0.041) and controls (P<0.01). Obestatin levels correlated positively with ghrelin levels, and obestatin levels were significantly increased in patients with cachexia (282.3+/-13.0 pg/ml) than patients without cachexia and controls (both P<0.01). However, the ghrelin to obestatin ratios (4.5+/-0.2) were significantly lower in CHF patients with cachexia than controls (P<0.01). Ghrelin and ratio of ghrelin to obestatin were independent predictors of the development of cardiac cachexia. No association was found between ghrelin, obestatin and New York Heart Association functional class, brain natriuretic peptide. There was disturbance of circulating ghrelin and obestatin in the CHF patients especially those with cachexia, which may have a role in the pathogenesis of cardiac cachexia in CHF.
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Affiliation(s)
- Xing Xin
- Department of Cardiovascular Diseases, Changhai Hospital, Second Military Medical University, 168 Changhai Road, Shanghai 200433, China
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34
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Perboni S, Inui A. Appetite and gastrointestinal motility: role of ghrelin-family peptides. Clin Nutr 2009; 29:227-34. [PMID: 19945199 DOI: 10.1016/j.clnu.2008.10.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Revised: 09/28/2008] [Accepted: 10/30/2008] [Indexed: 12/26/2022]
Abstract
Eating disorders, obesity and cachexia endanger the lives of millions of people worldwide. Fortunately, in last decade, there has been a rapid and substantial progress toward uncovering the molecular and neural mechanisms by which energy imbalance develops. In 1999, ghrelin was identified as the first orexigenic gut-derived peptide. It stimulates appetite and controls the gastric motility and the acid secretion through the activation of the growth hormone secretagogue-receptor. After the discovery of ghrelin, other forms of ghrelin-related proteins were isolated from the rat stomach. The unmodified des-n-octanoyl form (des-acyl ghrelin) and the recent obestatin act through distinct receptors and contrarily to acyl ghrelin, show an anorexigenic activity. The finding that these three peptide hormones derive from the same precursor exert opposing physiological actions, highlights the importance of post-translational regulatory mechanisms. Further investigations are required to highlight the complexity of ghrelin physiology in order to better understand the mechanisms regulating the energy balance and provide a successful treatment of eating disorders, obesity and cachexia.
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Affiliation(s)
- Simona Perboni
- Unità Operativa Day-Hospital Area Medica, Ospedale di Manerbio, Azienda Ospedaliera di Desenzano del Garda, Brescia I-25025, Italy.
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35
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Nagaraj S, Peddha MS, Manjappara UV. Fragment analogs as better mimics of obestatin. ACTA ACUST UNITED AC 2009; 158:143-8. [DOI: 10.1016/j.regpep.2009.08.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 08/07/2009] [Accepted: 08/16/2009] [Indexed: 10/20/2022]
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36
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Ghrelin and obestatin levels in type 2 diabetic patients with and without delayed gastric emptying. Dig Dis Sci 2009; 54:2161-6. [PMID: 19082715 DOI: 10.1007/s10620-008-0622-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Accepted: 11/03/2008] [Indexed: 12/12/2022]
Abstract
Alterations in the neurohumoral regulation of the upper intestine may change rhythmicity and pattern of ghrelin and obestatin, the latter presumably antagonizing ghrelin effects. Five nongastroparetic diabetic patients and five with gastroparesis were investigated. Over 390 min including breakfast and lunch, ghrelin was significantly lower in patients with gastroparesis compared with in those without (P = 0.015). Ghrelin subsequent to lunch decreased significantly (P = 0.011) in patients without gastroparesis, but not in gastroparetic patients (P = 0.669). Obestatin was similar in both groups and unchanged. No significant differences in ghrelin-to-obestatin ratio were observed (P = 0.530). Loss of rhythmicity in the ghrelin levels of gastroparetic diabetics highlights the importance of integrity of the neurohumoral-intestinal axis. Stable diurnal obestatin levels do not support the concept of interaction between ghrelin and obestatin in terms of regulation of food intake and gastric emptying.
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37
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Volante M, Rosas R, Ceppi P, Rapa I, Cassoni P, Wiedenmann B, Settanni F, Granata R, Papotti M. Obestatin in human neuroendocrine tissues and tumours: expression and effect on tumour growth. J Pathol 2009; 218:458-66. [DOI: 10.1002/path.2551] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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38
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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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39
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Annemie VD, Debby VD, Valentijn V, Bart DS, Walter L, Liliane S, Peter Paul DD. Central administration of obestatin fails to show inhibitory effects on food and water intake in mice. ACTA ACUST UNITED AC 2009; 156:77-82. [DOI: 10.1016/j.regpep.2009.04.014] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 04/06/2009] [Accepted: 04/29/2009] [Indexed: 11/29/2022]
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40
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Mitchell NA, Pepperell E, Ociepka S, Brown JD, Witherington J, Tuladhar B, Sanger GJ, Lee K, Cellek S. 5-hydroxyindalpine, an agonist at the putative 5-HT receptor, has no activity on human recombinant monoamine receptors but accelerates distension-induced peristalsis in mouse isolated colon. Neurogastroenterol Motil 2009; 21:760-e48. [PMID: 19309442 DOI: 10.1111/j.1365-2982.2009.01275.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Although the putative 5-HT(1P) receptor has been implicated to have a role in peristalsis, experiments which suggest this function are preliminary or have measured only components of the reflex. We have, therefore, further characterized a reported agonist at this receptor (5-hydroxyindalpine; 5-OHIP) and investigated the effects of 5-OHIP and 5-hydroxytrytophan-dipeptide (5-HTP-DP), a reported 5-HT(1P) receptor antagonist, on distension-induced peristalsis in mouse colon. The effects of 5-OHIP on intracellular calcium, cyclic adenosine monophosphate concentrations or GTPgammaS binding were measured in cell lines expressing human recombinant 5-HT(1A, 1B, 1D, 2A, 2B, 2C, 3, 4, 6, 7) and alpha(1A), alpha(1B), D(1), D(2), D(3), H(1), H(3) receptors. The effects of 5-OHIP and 5-HTP-DP on peristalsis were assessed by measuring changes in frequency and times to reach threshold of peristaltic contractions, as well as the threshold and maximum pressures of each peristaltic stroke. 5-hydroxyindalpine (1 nmol L(-1)-10 micromol L(-1)) had no significant activity at any of the receptors studied. However, 5-OHIP (0.1 nmol L(-1)-1 micromol L(-1)) concentration-dependently increased the frequency of peristalsis (EC(50) = 4.4 nmol L(-1)) and reduced the time taken to reach threshold and threshold pressure, without altering maximum pressures. The maximum effect of 5-OHIP was at 1 micromol L(-1) (68.0 +/- 14.5% increase in frequency); 10 micromol L(-1) decreased peristalsis. 5-hydroxytrytophan-dipeptide (1-300 nmol L(-1)) also increased the frequency of peristalsis and prevented the actions of 5-OHIP. The higher concentration (1 micromol L(-1)) transiently inhibited peristalsis and after recovery, prevented the actions of 5-OHIP but not the excitatory activity of the cholinesterase inhibitor neostigmine. In summary, the present data demonstrate an interaction of '5-HT(1P)-ligands' with the peristaltic reflex. However, the absence of an effect of 5-OHIP on a range of different monoamine receptors continues to highlight the need to investigate the identity of the putative 5-HT(1P) receptor.
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Affiliation(s)
- N A Mitchell
- Immuno Inflammation Centre of Excellence in Drug Discovery, GlaxoSmithKline, Stevenage, UK
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41
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Bassil AK, Bourdu S, Townson KA, Wheeldon A, Jarvie EM, Zebda N, Abuin A, Grau E, Livi GP, Punter L, Latcham J, Grimes AM, Hurp DP, Downham KM, Sanger GJ, Winchester WJ, Morrison AD, Moore GBT. UDP-glucose modulates gastric function through P2Y14 receptor-dependent and -independent mechanisms. Am J Physiol Gastrointest Liver Physiol 2009; 296:G923-30. [PMID: 19164486 DOI: 10.1152/ajpgi.90363.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
P2Y receptors have been reported to modulate gastrointestinal functions. The newest family member is the nucleotide-sugar receptor P2Y14. P2ry14 mRNA was detected throughout the rat gut, with the highest level being in the forestomach. We investigated the role of the receptor in stomach motility using cognate agonists and knockout (KO) mice. In rat isolated forestomach, 100 microM UDP-glucose and 100 muM UDP-galactose both increased the baseline muscle tension (BMT) by 6.2+/-0.6 and 1.6+/-0.6 mN (P<0.05, n=3-4), respectively, and the amplitude of contractions during electrical field stimulation (EFS) by 3.7+/-1.7 and 4.3+/-2.5 mN (P<0.05, n=3-4), respectively. In forestomach from wild-type (WT) mice, 100 microM UDP-glucose increased the BMT by 1.0+/-0.1 mN (P<0.05, n=6) but this effect was lost in the KO mice (change of -0.1+/-0.1 mN, n=6). The 100 microM UDP-glucose also increased the contraction amplitude during EFS in this tissue from the WT animals (0.9+/-0.4 mN, P < 0.05, n=6) but not from the KO mice (0.0+/-0.2 mN, n=6). In vivo, UDP-glucose at 2,000 mg/kg ip reduced gastric emptying in rats by 49.7% (P<0.05, n=4-6) and in WT and KO mice by 56.1 and 66.2%, respectively (P<0.05, n=7-10) vs. saline-treated control animals. There was no significant difference in gastric emptying between WT and KO animals receiving either saline or d-glucose. These results demonstrate a novel function of the P2Y14 receptor associated with contractility in the rodent stomach that does not lead to altered gastric emptying after receptor deletion and an ability of UDP-glucose to delay gastric emptying without involving the P2Y14 receptor.
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Affiliation(s)
- Anna K Bassil
- Department of Gastrointestinal Research, Neurology and Gastrointestinal Centre of Excellence for Drug Discovery, Harlow, UK
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Dong XY, He JM, Tang SQ, Li HY, Jiang QY, Zou XT. Is GPR39 the natural receptor of obestatin? Peptides 2009; 30:431-8. [PMID: 18977259 DOI: 10.1016/j.peptides.2008.09.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2008] [Revised: 08/25/2008] [Accepted: 09/25/2008] [Indexed: 12/15/2022]
Abstract
GPR39, an orphan receptor belonging to the family of G protein-coupled receptors, was originally reported to be the receptor of obestatin. However recently, numerous reports have questioned this conclusion. In mammals, GPR39 was reported to be involved in the regulation of gastrointestinal and the metabolic functions. In this article, a latest and brief review on the receptor family, structure, distribution and physiological functions of GPR39 has been reported.
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Affiliation(s)
- Xiao-Ying Dong
- College of Yingdong Bioengineering, Shaoguan University, Daxue Avenue, Zhenjiang District, Shaoguan 512005, China
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43
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Shafton AD, Sanger GJ, Witherington J, Brown JD, Muir A, Butler S, Abberley L, Shimizu Y, Furness JB. Oral administration of a centrally acting ghrelin receptor agonist to conscious rats triggers defecation. Neurogastroenterol Motil 2009; 21:71-7. [PMID: 18694442 DOI: 10.1111/j.1365-2982.2008.01176.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Agonists of ghrelin receptors that cross the blood-brain barrier, but not ghrelin itself, administered peripherally (intravenous or subcutaneous), cause defecation by acting on centres in the lumbo-sacral spinal cord. It is not established whether orally administered ghrelin receptor agonists can have this action. We tested GSK894281 for its effectiveness at the ghrelin receptor and its ability to cross the blood-brain barrier. GSK894281 was effective at the human and rat ghrelin receptors at 1-10 nmol L(-1), but was >1000-fold less potent at the motilin receptor. It achieved a similar blood concentration by oral or intravenous administration. Oral bioavailability was 74% and brain : blood ratio at steady state was 0.7 : 1. GSK894281 administered orally (1-100 mg kg(-1)) caused a prompt, dose-related production of faecal pellets; at 10 mg kg(-1) faecal output was four times greater than after carrier. The output was the greatest in the first half hour and subsided over the next 90 min. At an oral dose of 10 mg kg(-1), the compound was effective on eight successive days. Faecal output was, on average, increased threefold over control in the 2 h after administration on each of the 8 days. This dose also significantly increased food consumption. Rats showed no adverse behavioural effects to the drug on a single application, but at the end of a week of administration they avoided the gavaging pipette. Oral administration of ghrelin receptor agonists that enter the central nervous system could possibly be used to relieve acute cases of constipation or to clear the bowel for colonoscopy.
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Affiliation(s)
- A D Shafton
- Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria, Australia
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44
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Egido EM, Hernández R, Marco J, Silvestre RA. Effect of obestatin on insulin, glucagon and somatostatin secretion in the perfused rat pancreas. ACTA ACUST UNITED AC 2009; 152:61-6. [DOI: 10.1016/j.regpep.2008.08.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 07/08/2008] [Accepted: 08/07/2008] [Indexed: 11/17/2022]
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Nunes S, Nogueira-Silva C, Dias E, Moura RS, Correia-Pinto J. Ghrelin and obestatin: different role in fetal lung development? Peptides 2008; 29:2150-8. [PMID: 18789988 DOI: 10.1016/j.peptides.2008.08.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 08/07/2008] [Accepted: 08/08/2008] [Indexed: 12/28/2022]
Abstract
Ghrelin and obestatin are two proteins that originate from post-translational processing of the preproghrelin peptide. Various authors claim an opposed role of ghrelin and obestatin in several systems. Preproghrelin mRNA is significantly expressed in airway epithelium throughout lung development, predominantly during the earliest stages. The aim of this study was to evaluate the role of ghrelin and obestatin in fetal lung development in vitro. Immunohistochemistry studies were performed at different gestational ages in order to clarify the expression pattern of ghrelin, GHS-R1a, obestatin and GPR39 during fetal lung development. Fetal rat lung explants were harvested at 13.5 days post-conception (dpc) and cultured during 4 days with increasing doses of total ghrelin, acylated ghrelin, desacyl-ghrelin, ghrelin antagonist (D-Lys(3)-GHRP-6) or obestatin. Immunohistochemistry studies demonstrated that ghrelin, GHS-R1a, obestatin and GPR39 proteins were expressed in primitive rat lung epithelium throughout all studied gestational ages. Total and acylated ghrelin supplementation significantly increased the total number of peripheral airway buds, whereas desacyl-ghrelin induced no effect. Moreover, GHS-R1a antagonist significantly decreased lung branching. Finally, obestatin supplementation induced no significant effect in the measured parameters. The present study showed that ghrelin has a positive effect in fetal lung development through its GHS-R1a receptor, whereas obestatin has no effect on lung branching.
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Affiliation(s)
- Susana Nunes
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
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46
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Fujimiya M, Asakawa A, Ataka K, Kato I, Inui A. Different effects of ghrelin, des-acyl ghrelin and obestatin on gastroduodenal motility in conscious rats. World J Gastroenterol 2008; 14:6318-26. [PMID: 19009646 PMCID: PMC2766112 DOI: 10.3748/wjg.14.6318] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Three peptides, ghrelin, des-acyl ghrelin and obestatin are derived from a common prohormone, preproghrelin by posttranslational processing, originating from endocrine cells in the stomach. To examine the effects of these peptides, we applied the manometric measurement of gastrointestinal motility in freely moving conscious rat models. Ghrelin exerts stimulatory effects on the motility of antrum and duodenum in both fed and fasted state of animals. Des-acyl ghrelin exerts inhibitory effects on the motility of antrum, but not on the motility of duodenum in the fasted state of animals. Obestatin exerts inhibitory effects on the motility of antrum and duodenum in the fed state, but not in the fasted state of animals. NPY Y2 or Y4 receptors in the brain may mediate the action of ghrelin, CRF type 2 receptors in the brain mediate the action of des-acyl ghrelin, whereas CRF type 1 and type 2 receptors in the brain mediate the action of obestatin. Vagal afferent pathways might be involved in the action of ghrelin, but not involved in the action of des-acyl ghrelin, whereas vagal afferent pathways might be partially involved in the action of obestatin.
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47
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Rudholm T, Hellström PM, Theodorsson E, Campbell CA, McLean PG, Näslund E. Bravo capsule system optimizes intragastric pH monitoring over prolonged time: Effects of ghrelin on gastric acid and hormone secretion in the rat. World J Gastroenterol 2008; 14:6180-7. [PMID: 18985808 PMCID: PMC2761579 DOI: 10.3748/wjg.14.6180] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To evaluate measurements of intragastric pH with the Bravo capsule system over a prolonged time.
METHODS: A Bravo capsule was placed inside the rat gastric body and pH was studied for periods up to five consecutive days. For comparison, a gastric fistula model was used. Effects of ghrelin and esomeprazole, with or without pentagastrin, on gastric pH were studied. In addition, effects of esomeprazole on plasma ghrelin, gastrin and somatostatin were analyzed.
RESULTS: All rats recovered after surgery. The average 24-h pH during free feeding was 2.3 ± 0.1 (n = 20) with a variation of 18% ± 6% over 5 d. Ghrelin, 2400 pmol/kg, t.i.d. increased pH from 1.7 ± 0.1 to 3.1 ± 0.3 (P < 0.01) as recorded with the Bravo system. After esomeprazole (1 mg/kg, 3 mg/kg and 5 mg/kg) there was a dose-dependent pH increase of maximally 3.4 ± 0.1, with day-to-day variation over the entire period of 8% ± 3%. The fistula and pH studies generated similar results. Acid inhibition with esomeprazole increased plasma ghrelin from 10 ± 2 pmol/L to 65 ± 26 pmol/L (P < 0.001), and somatostatin from 10 ± 2 pmol/L to 67 ± 18 pmol/L (P < 0.001).
CONCLUSION: pH measurements with the Bravo capsule are reliable, and comparable to those of the gastric fistula model. The Bravo system optimizes accurate intragastric pH monitoring over prolonged periods and allows both short- and long-term evaluation of effects of drugs and hormones.
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Wu ZQ, Wang WG, Wang ZG, Zheng Q. Roles of obestatin and its receptor in regulation of gastrointestinal motility. Shijie Huaren Xiaohua Zazhi 2008; 16:2974-2979. [DOI: 10.11569/wcjd.v16.i26.2974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Obestatin, a novel 23-amino acid amidated brain/gut peptide synthesized in the stomach, was initially reported to reduce food intake, body weight gain and gastric emptying and suppress intestinal motility through an interaction with the orphan G-protein coupled receptor GPR39. Obestatin is derived from the same gene product as ghrelin by differential posttranslational processing and modification, which exerts effects opposite to those of ghrelin. However, recent reports have shown that the above findings had been questioned by several groups. According to the controversy that obestatin is unlikely to be the endogenous ligand for GPR39 and obestatin has no impacts on gastrointestinal motility, this paper reviews the studies related to obestatin and GPR39 and its impacts on gastrointestinal motility.
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Erlanson-Albertsson C, Lindqvist A. Vagotomy and accompanying pyloroplasty down-regulates ghrelin mRNA but does not affect ghrelin secretion. ACTA ACUST UNITED AC 2008; 151:14-8. [PMID: 18804492 DOI: 10.1016/j.regpep.2008.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 05/08/2008] [Accepted: 08/28/2008] [Indexed: 11/25/2022]
Abstract
In this study, we have examined how the lack of vagus activity affects the long-term secretion of total and active ghrelin. We subjected mice to sham-operation, pyloroplasty or vagotomy and pyloroplasty. The study lasted for 2 weeks, during which body weight development and daily food intake was monitored. At the end of the study, the mice were sacrificed, and serum and fundus were collected. Measurements of total and active serum ghrelin revealed no difference between the surgical groups and sham-operated mice, despite the fact that fundic ghrelin mRNA was down-regulated. The results presented here suggest that the vagus activity is not required for the long-term secretion of neither total nor active ghrelin in mice. They also suggest that fundic ghrelin mRNA expression is affected by pyloroplasty and vagotomy but that this effect does not translate into changes in ghrelin levels in the circulation.
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Chen CY, Chien EJ, Chang FY, Lu CL, Luo JC, Lee SD. Impacts of peripheral obestatin on colonic motility and secretion in conscious fed rats. Peptides 2008; 29:1603-8. [PMID: 18565623 DOI: 10.1016/j.peptides.2008.05.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 05/03/2008] [Accepted: 05/07/2008] [Indexed: 12/14/2022]
Abstract
Obestatin, a novel putative 23-amino acid peptide, was found to be derived from a mammalian preproghrelin gene by using a bioinformatics approach. Although the effects of obestatin on food intake and upper gut motility remain controversial, no studies have been carried out to explore its influence on lower gut motility and secretion. We investigated the impacts of intravenous (IV) injection of obestatin on rat colonic motor and secretory functions. Colonic transit time, fecal pellet output, and fecal content were measured in freely fed, conscious rats, which were chronically implanted with IV and colonic catheters. To test the validity of this animal model, human/rat corticotropin-releasing factor (h/rCRF) served as a stimulatory inducer of colonic motility and secretion. IV injection of obestatin (45, 100, and 300 nmol/kg) did not affect the colonic transit time, whereas IV injection of h/rCRF (30 nmol/kg) effectively accelerated colonic transit time. IV obestatin, in every dose we tested, also did not modify fecal pellet output, frequency of watery diarrhea, total fecal weight, fecal dried solid weight, or fecal fluid weight in the first hour after injection. On the other hand, IV injection of h/rCRF significantly enhanced fecal pellet output, as well as increased the frequency of watery diarrhea, total fecal weight, fecal dried solid weight, and fecal fluid weight during the first hour after injection compared with IV saline controls. In conclusion, peripheral obestatin administration has no impact on colonic motility and secretion in conscious fed rats.
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Affiliation(s)
- C Y Chen
- Division of Gastroenterology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.
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