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Hayakawa S, Tanaka T, Ogawa R, Ito S, Ueno S, Koyama H, Tomotaka O, Sagawa H, Tanaka T, Iwakura H, Takahashi H, Matsuo Y, Mitsui A, Kimura M, Takahashi S, Takiguchi S. Potential Role of TRPV4 in Stretch-Induced Ghrelin Secretion and Obesity. Int J Endocrinol 2022; 2022:7241275. [PMID: 36397882 PMCID: PMC9666045 DOI: 10.1155/2022/7241275] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 10/18/2022] [Accepted: 10/25/2022] [Indexed: 11/09/2022] Open
Abstract
Obesity is an important health problem, which can be prevented through appetite control. Ghrelin is an appetite-stimulating hormone considered to promote obesity. Thus, we examined whether gastric stretching affects ghrelin secretion. We investigated the role of transient receptor potential vanilloid 4 (TRPV4) in gastric glands in the regulation of ghrelin secretion. TRPV4 immunostaining was performed in tissue samples from 57 patients who underwent gastrectomy. TRPV4 expression was compared between patients with (body mass index (BMI) ≥ 30) and without (BMI <30) obesity. For in vitro experiments, we used MGN3-1 cells, a ghrelin-producing cell line derived from mice. To investigate the bioactivity of TRPV4, MGN3-1 cells were treated with TRPV4 agonists and antagonists, and changes in intracellular Ca2+ concentration were confirmed. The concentration of ghrelin in the cell supernatant was measured using the ELISA with and without 120% stretch stimulation. TRPV4 expression was significantly higher in patients with obesity than in those without at all sites, except the fornix. Immunostaining confirmed the expression of TRPV4 in MGN3-1 cells. TRPV4 agonist administration increased intracellular Ca2+ concentration and ghrelin secretion in MGN3-1 cells, whereas the administration of the agonist combined with the antagonist decreased intracellular Ca2+ concentration and ghrelin secretion. Ghrelin secretion significantly increased in response to a 120% stretch in MGN3-1 cells. However, secretion was not increased by stretch when cells were treated with a TRPV4 antagonist. TRPV4 regulates ghrelin secretion in response to stretch in the stomach, which may affect body weight.
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Affiliation(s)
- Shunsuke Hayakawa
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Tatsuya Tanaka
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Ryo Ogawa
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Sunao Ito
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Shuhei Ueno
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Hiroyuki Koyama
- Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Okubo Tomotaka
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Hiroyuki Sagawa
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Tomohiro Tanaka
- Department of Gastroenterology and Metabolism, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Hiroshi Iwakura
- Department of Pharmacotherapeutics, Wakayama Medical University, Kimiidera, Wakayama, Wakayama, Japan
| | - Hiroki Takahashi
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Yoichi Matsuo
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Akira Mitsui
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Masahiro Kimura
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Satoru Takahashi
- Department of Experimental Pathology and Tumor Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Shuji Takiguchi
- Department of Gastroenterological Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
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Romański KW. Importance of the enteric nervous system in the control of the migrating motility complex. Physiol Int 2017; 104:97-129. [PMID: 28665193 DOI: 10.1556/2060.104.2017.2.4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The migrating motility complex (MMC), a cyclical phenomenon, represents rudimentary motility pattern in the gastrointestinal tract. The MMC is observed mostly in the stomach and gut of man and numerous animal species. It contains three or four phases, while its phase III is the most characteristic. The mechanisms controlling the pattern are unclear in part, although the neural control of the MMC seems crucial. The main goal of this article was to discuss the importance of intrinsic innervation of the gastrointestinal tract in MMC initiation, migration, and cessation to emphasize that various MMC-controlling mechanisms act through the enteric nervous system. Two main neural regions, central and peripheral, are able to initiate the MMC. However, central regulation of the MMC may require cooperation with the enteric nervous system. When central mechanisms are not active, the MMC can be initiated peripherally in any region of the small bowel. The enteric nervous system affects the MMC in response to the luminal stimuli which can contribute to the initiation and cessation of the cycle, and it may evoke irregular phasic contractions within the pattern. The hormonal regulators released from the endocrine cells may exert a modulatory effect upon the MMC mostly through the enteric nervous system. Their central action could also be considered. It can be concluded that the enteric nervous system is involved in the great majority of the MMC-controlling mechanisms.
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Affiliation(s)
- K W Romański
- 1 Department of Animal Physiology, Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences , Wrocław, Poland
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Zan J, Song L, Wang J, Zou R, Hong F, Zhao J, Cheng Y, Xu M. Role of ghrelin in small intestinal motility following pediatric intracerebral hemorrhage in mice. Mol Med Rep 2017; 16:6958-6966. [DOI: 10.3892/mmr.2017.7468] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 04/25/2017] [Indexed: 11/06/2022] Open
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Hauberg K, Kohlmeier KA. The appetite-inducing peptide, ghrelin, induces intracellular store-mediated rises in calcium in addiction and arousal-related laterodorsal tegmental neurons in mouse brain slices. Peptides 2015; 65:34-45. [PMID: 25645492 DOI: 10.1016/j.peptides.2015.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Revised: 01/21/2015] [Accepted: 01/21/2015] [Indexed: 12/16/2022]
Abstract
Ghrelin, a gut and brain peptide, has recently been shown to be involved in motivated behavior and regulation of the sleep and wakefulness cycle. The laterodorsal tegmental nucleus (LDT) is involved in appetitive behavior and control of the arousal state of an organism, and accordingly, behavioral actions of ghrelin could be mediated by direct cellular actions within this nucleus. Consistent with this interpretation, postsynaptically mediated depolarizing membrane actions of ghrelin on LDT neurons have been reported. Direct actions were ascribed solely to closure of a potassium conductance however this peptide has been shown in other cell types to lead to rises in calcium via release of calcium from intracellular stores. To determine whether ghrelin induced intracellular calcium rises in mouse LDT neurons, we conducted calcium imaging studies in LDT brain slices loaded with the calcium binding dye, Fura-2AM. Ghrelin elicited TTX-insensitive changes in dF/F indicative of rises in calcium, and a portion of these rises were independent of membrane depolarization, as they persisted in conditions of high extracellular potassium solutions and were found to involve SERCA-pump mediated intracellular calcium stores. Involvement of the ghrelin receptor (GHR-S) in these actions was confirmed. Taken together with other studies, our data suggest that ghrelin has multiple cellular actions on LDT cells. Ghrelin's induction of calcium via intracellular release in the LDT could play a role in behavioral actions of this peptide as the LDT governs processes involved in stimulation of motivated behavior and control of cortical arousal.
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Affiliation(s)
- Katrine Hauberg
- Department of Drug Design and Pharmacology, Faculty of Health Sciences, Universitetsparken 2, University of Copenhagen, Copenhagen 2100, Denmark
| | - Kristi A Kohlmeier
- Department of Drug Design and Pharmacology, Faculty of Health Sciences, Universitetsparken 2, University of Copenhagen, Copenhagen 2100, Denmark.
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Heldsinger A, Grabauskas G, Wu X, Zhou S, Lu Y, Song I, Owyang C. Ghrelin induces leptin resistance by activation of suppressor of cytokine signaling 3 expression in male rats: implications in satiety regulation. Endocrinology 2014; 155:3956-69. [PMID: 25060362 PMCID: PMC4164930 DOI: 10.1210/en.2013-2095] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The anorexigenic adipocyte-derived hormone leptin and the orexigenic hormone ghrelin act in opposition to regulate feeding behavior via the vagal afferent pathways. The mechanisms by which ghrelin exerts its inhibitory effects on leptin are unknown. We hypothesized that ghrelin activates the exchange protein activated by cAMP (Epac), inducing increased SOCS3 expression, which negatively affects leptin signal transduction and neuronal firing in nodose ganglia (NG) neurons. We showed that 91 ± 3% of leptin receptor (LRb) -bearing neurons contained ghrelin receptors (GHS-R1a) and that ghrelin significantly inhibited leptin-stimulated STAT3 phosphorylation in rat NG neurons. Studies of the signaling cascades used by ghrelin showed that ghrelin caused a significant increase in Epac and suppressor of cytokine signaling 3 (SOCS3) expression in cultured rat NG neurons. Transient transfection of cultured NG neurons to silence SOCS3 and Epac genes reversed the inhibitory effects of ghrelin on leptin-stimulated STAT3 phosphorylation. Patch-clamp studies and recordings of single neuronal discharges of vagal primary afferent neurons showed that ghrelin markedly inhibited leptin-stimulated neuronal firing, an action abolished by silencing SOCS3 expression in NG. Plasma ghrelin levels increased significantly during fasting. This was accompanied by enhanced SOCS3 expression in the NG and prevented by treatment with a ghrelin antagonist. Feeding studies showed that silencing SOCS3 expression in the NG reduced food intake evoked by endogenous leptin. We conclude that ghrelin exerts its inhibitory effects on leptin-stimulated neuronal firing by increasing SOCS3 expression. The SOCS3 signaling pathway plays a pivotal role in ghrelin's inhibitory effect on STAT3 phosphorylation, neuronal firing, and feeding behavior.
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Affiliation(s)
- Andrea Heldsinger
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48019
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Nutritional state-dependent ghrelin activation of vasopressin neurons via retrograde trans-neuronal-glial stimulation of excitatory GABA circuits. J Neurosci 2014; 34:6201-13. [PMID: 24790191 DOI: 10.1523/jneurosci.3178-13.2014] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Behavioral and physiological coupling between energy balance and fluid homeostasis is critical for survival. The orexigenic hormone ghrelin has been shown to stimulate the secretion of the osmoregulatory hormone vasopressin (VP), linking nutritional status to the control of blood osmolality, although the mechanism of this systemic crosstalk is unknown. Here, we show using electrophysiological recordings and calcium imaging in rat brain slices that ghrelin stimulates VP neurons in the hypothalamic paraventricular nucleus (PVN) in a nutritional state-dependent manner by activating an excitatory GABAergic synaptic input via a retrograde neuronal-glial circuit. In slices from fasted rats, ghrelin activation of a postsynaptic ghrelin receptor, the growth hormone secretagogue receptor type 1a (GHS-R1a), in VP neurons caused the dendritic release of VP, which stimulated astrocytes to release the gliotransmitter adenosine triphosphate (ATP). ATP activation of P2X receptors excited presynaptic GABA neurons to increase GABA release, which was excitatory to the VP neurons. This trans-neuronal-glial retrograde circuit activated by ghrelin provides an alternative means of stimulation of VP release and represents a novel mechanism of neuronal control by local neuronal-glial circuits. It also provides a potential cellular mechanism for the physiological integration of energy and fluid homeostasis.
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Eating and stress at work: The need for public health promotion intervention and an opportunity for food product development? Trends Food Sci Technol 2014. [DOI: 10.1016/j.tifs.2013.10.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Avau B, Carbone F, Tack J, Depoortere I. Ghrelin signaling in the gut, its physiological properties, and therapeutic potential. Neurogastroenterol Motil 2013; 25:720-32. [PMID: 23910374 DOI: 10.1111/nmo.12193] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Accepted: 06/26/2013] [Indexed: 02/08/2023]
Abstract
BACKGROUND Ghrelin, an orexigenic hormone secreted from the stomach, was soon after its discovery hypothesized to be a prokinetic agent, due to its homology to motilin. Studies in animals and humans, using ghrelin and ghrelin receptor agonists, confirmed this hypothesis, suggesting a therapeutic potential for the ghrelin receptor in the treatment of gastrointestinal motility disorders. Precilinical studies demonstrated that ghrelin can act directly on ghrelin receptors on the enteric nervous system, but the predominant route of action under physiological circumstances is signaling via the vagus nerve in the upper gastrointestinal tract and the pelvic nerves in the colon. Different pharmaceutical companies have designed stable ghrelin mimetics that revealed promising results in trials for the treatment of diabetic gastroparesis and post-operative ileus. Nevertheless, no drug was able to reach the market so far, facing problems proving superiority over placebo treatment in larger trials. PURPOSE This review aims to summarize the road that led to the current knowledge concerning the prokinetic properties of ghrelin with a focus on the therapeutic potential of ghrelin receptor agonists in the treatment of hypomotility disorders. In addition, we outline some of the problems that could be at the basis of the negative outcome of the trials with ghrelin agonists and question whether the right target groups were selected. It is clear that a new approach is needed to develop marketable drugs with this class of gastroprokinetic agents.
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Affiliation(s)
- B Avau
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
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STENGEL A, GOEBEL-STENGEL M, WANG L, LUCKEY A, HU E, RIVIER J, TACHÉ Y. Central administration of pan-somatostatin agonist ODT8-SST prevents abdominal surgery-induced inhibition of circulating ghrelin, food intake and gastric emptying in rats. Neurogastroenterol Motil 2011; 23:e294-308. [PMID: 21569179 PMCID: PMC3117963 DOI: 10.1111/j.1365-2982.2011.01721.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Activation of brain somatostatin receptors (sst(1-5) ) with the stable pan-sst(1-5) somatostatin agonist, ODT8-SST blocks acute stress and central corticotropin-releasing factor (CRF)-mediated activation of endocrine and adrenal sympathetic responses. Brain CRF signaling is involved in delaying gastric emptying (GE) immediately post surgery. We investigated whether activation of brain sst signaling pathways modulates surgical stress-induced inhibition of gastric emptying and food intake. METHODS Fasted rats were injected intracisternally (i.c.) with somatostatin agonists and underwent laparotomy and 1-min cecal palpation. Gastric emptying of a non-nutrient solution and circulating acyl and desacyl ghrelin levels were assessed 50min post surgery. Food intake was monitored for 24 h. KEY RESULTS The abdominal surgery-induced inhibition of GE (65%), food intake (73% at 2h) and plasma acyl ghrelin levels (67%) was completely prevented by ODT8-SST (1μg per rat, i.c.). The selective sst(5) agonist, BIM-23052 prevented surgery-induced delayed GE, whereas selective sst(1) , sst(2) , or sst(4) agonists had no effect. However, the selective sst(2) agonist, S-346-011 (1μg per rat, i.c.) counteracted the abdominal surgery-induced inhibition of acyl ghrelin and food intake but not the delayed GE. The ghrelin receptor antagonist, [D-Lys(3) ]-GHRP-6 (0.93mg kg(-1) , intraperitoneal, i.p.) blocked i.p. ghrelin-induced increased GE, while not influencing i.c. ODT8-SST-induced prevention of delayed GE and reduced food intake after surgery. CONCLUSIONS & INFERENCES ODT8-SST acts in the brain to prevent surgery-induced delayed GE likely via activating sst(5) . ODT8-SST and the sst(2) agonist prevent the abdominal surgery-induced decrease in food intake and plasma acyl ghrelin indicating dissociation between brain somatostatin signaling involved in preventing surgery-induced suppression of GE and feeding response.
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Affiliation(s)
- A. STENGEL
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Health Care System, CA 90073, USA
| | - M. GOEBEL-STENGEL
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Health Care System, CA 90073, USA
| | - L. WANG
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Health Care System, CA 90073, USA
| | - A. LUCKEY
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Health Care System, CA 90073, USA
| | - E. HU
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Health Care System, CA 90073, USA
| | - J. RIVIER
- Peptide Biology Laboratories, Salk Institute, La Jolla, CA, USA
| | - Y. TACHÉ
- CURE/Digestive Diseases Research Center, Center for Neurobiology of Stress, Department of Medicine, Digestive Diseases Division at the University of California Los Angeles, and VA Greater Los Angeles Health Care System, CA 90073, USA
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Bülbül M, Babygirija R, Zheng J, Ludwig K, Xu H, Lazar J, Takahashi T. Food intake and interdigestive gastrointestinal motility in ghrelin receptor mutant rats. J Gastroenterol 2011; 46:469-78. [PMID: 21258824 DOI: 10.1007/s00535-010-0366-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 12/19/2010] [Indexed: 02/04/2023]
Abstract
BACKGROUND Ghrelin is the endogenous ligand for the growth hormone secretagogue receptor (GHSR). Ghrelin regulates feeding activity and interdigestive contractions of the stomach in rodents. To investigate the role of endogenous ghrelin in the digestive system, we have developed GHSR-mutant rats, named FHH-Ghsr(m1Mcwi), using the Fawn-Hooded Hypertensive (FHH) parental strain. METHODS N-ethyl-N-nitrosourea (ENU) was used as a mutagen. Genomic DNA prepared from a tail clip was analyzed using the targeting induced local lesions in genomes (TILLING) approach. The non-synonymous mutation in position 343 (NM_032075) led to the generation of a premature stop codon, causing deletion of the last 22 amino acids at the C-terminal of ghrelin receptor protein. Spontaneous and ghrelin-stimulated food intake was measured in wild-type (WT) FHH and FHH-Ghsr(m1Mcwi) rats. For interdigestive motility recording, two strain gauge transducers were sutured on the antrum and duodenum. Spontaneous gastroduodenal contractions were recorded in freely moving conscious rats. RESULTS Ghrelin (40 μg/kg) failed to stimulate food intake in the mutant rats, while spontaneous food intake was not significantly different between the WT rats and FHH-Ghsr(m1Mcwi) rats. Phase III-like contractions were observed in stomach and duodenum both in the WT and FHH-Ghsr(m1Mcwi) rats. In the WT rats, ghrelin (12 μg/kg) administration enhanced spontaneous phase III-like contractions, and a GHSR antagonist, (D-lys3)GHRP-6 (0.28 mg/kg), abolished the spontaneous phase III-like contractions. In FHH-Ghsr(m1Mcwi) rats, ghrelin and (D-lys3)GHRP-6 did not affect phase III-like contractions. CONCLUSIONS It is suggested that the intact GHSR structure is essential for the ghrelin-dependent regulation of interdigestive motility and feeding behavior. Even in FHH-Ghsr(m1Mcwi) rats, spontaneous gastric phase III-like contractions were still observed, suggesting the development of a compensatory mechanism to maintain these contractions.
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Affiliation(s)
- Mehmet Bülbül
- Department of Surgery, Medical College of Wisconsin and Zablocki VA Medical Center, 5000 West National Avenue, Milwaukee, WI 53295, USA
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Hansen MB, Wallin L, Husebye E, Dommergaard L, Gregersen H. Migrating Motor Complex in Colectomized Ileo Stoma Patients. Basic Clin Pharmacol Toxicol 2011; 108:349-58. [DOI: 10.1111/j.1742-7843.2010.00665.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Zietlow A, Nakajima H, Taniguchi H, Ludwig K, Takahashi T. Association between plasma ghrelin and motilin levels during MMC cycle in conscious dogs. ACTA ACUST UNITED AC 2010; 164:78-82. [PMID: 20609429 DOI: 10.1016/j.regpep.2010.05.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 05/10/2010] [Accepted: 05/25/2010] [Indexed: 11/16/2022]
Abstract
BACKGROUND Migrating motor complex (MMC) is well characterized by the appearance of gastrointestinal contractions in the interdigestive state. Gastric phase III contractions of MMC are regulated by motilin, but not ghrelin, in dogs. Ghrelin regulates feeding activity in dogs and rodents. It remains unclear how motilin and ghrelin interact during the MMC cycle in dogs. METHODS Four strain gauge transducers were implanted on stomach and intestine in 6 female dogs. To investigate the correlation between ghrelin and motilin, plasma motilin and acyl ghrelin (active type) levels were measured by radioimmunoassay (RIA) during MMC cycle. RESULTS The peak of plasma motilin levels was always observed at the period of gastric phase III contractions. The peak of ghrelin levels were followed 20-25 min after the peak of plasma motilin levels in 13 cases of 18 observations (72.2%). These were frequently observed at the early stage of gastric phase I contractions. In 3 of 16 observations (18.8%), the ghrelin peak was not associated with the motilin peaks. Immediately after the feeding, the interdigestive GI motor pattern was changed to the postprandial pattern. No significant increases of the plasma motilin levels and ghrelin levels were observed after the feeding. CONCLUSION This is the first demonstration showing the correlation between ghrelin and motilin levels during gastric MMC cycle in conscious dogs. As it is rather difficult to evaluate the hunger score in dogs, it remains unclear whether increased ghrelin levels after finishing gastric phase III contractions may mediate hunger sensation in dogs.
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Affiliation(s)
- Aaron Zietlow
- Department of Surgery, Medical College of Wisconsin and Zablocki VA Medical Center, Milwaukee, WI, USA
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The prokinetic face of ghrelin. INTERNATIONAL JOURNAL OF PEPTIDES 2010; 2010. [PMID: 20721347 PMCID: PMC2915793 DOI: 10.1155/2010/493614] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 12/03/2009] [Indexed: 01/03/2023]
Abstract
This review evaluated published data regarding the effects of ghrelin on GI motility using the PubMed database for English articles from 1999 to September 2009. Our strategy was to combine all available information from previous literature, in order to provide a complete structured review on the prokinetic properties of exogenous ghrelin and its potential use for treatment of
various GI dysmotility ailments. We classified the literature into two major groups, depending on whether studies were done in health
or in disease. We sub-classified the studies into stomach, small intestinal and colon studies, and broke them down further into
studies done in vitro, in vivo (animals) and in humans. Further more, the reviewed studies were presented in a chronological order
to guide the readers across the scientific advances in the field. The review shows evidences that ghrelin and its (receptor)
agonists possess a strong prokinetic potential to serve in the treatment of diabetic, neurogenic or idiopathic gastroparesis and
possibly, chemotherapy-associated dyspepsia, postoperative, septic or post-burn ileus, opiate-induced bowel dysfunction and chronic
idiopathic constipation. Further research is necessary to close the gap in knowledge about the effect of ghrelin on the human
intestines in health and disease.
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Castañeda TR, Tong J, Datta R, Culler M, Tschöp MH. Ghrelin in the regulation of body weight and metabolism. Front Neuroendocrinol 2010; 31:44-60. [PMID: 19896496 DOI: 10.1016/j.yfrne.2009.10.008] [Citation(s) in RCA: 243] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 10/26/2009] [Accepted: 10/26/2009] [Indexed: 12/25/2022]
Abstract
Ghrelin, a peptide hormone predominantly produced by the stomach, was isolated as the endogenous ligand for the growth hormone secretagogue receptor. Ghrelin is a potent stimulator of growth hormone (GH) secretion and is the only circulatory hormone known to potently enhance feeding and weight gain and to regulate energy homeostasis following central and systemic administration. Therapeutic intervention with ghrelin in catabolic situations may induce a combination of enhanced food intake, increased gastric emptying and nutrient storage, coupled with an increase in GH thereby linking nutrient partitioning with growth and repair processes. These qualities have fostered the idea that ghrelin-based compounds may have therapeutic utility in treating malnutrition and wasting induced by various sub-acute and chronic disorders. Conversely, compounds that inhibit ghrelin action may be useful for the prevention or treatment of metabolic syndrome components such as obesity, impaired lipid metabolism or insulin resistance. In recent years, the effects of ghrelin on glucose homeostasis, memory function and gastrointestinal motility have attracted considerable amount of attention and revealed novel therapeutic targets in treating a wide range of pathologic conditions. Furthermore, discovery of ghrelin O-acyltransferase has also opened new research opportunities that could lead to major understanding of ghrelin physiology. This review summarizes the current knowledge on ghrelin synthesis, secretion, mechanism of action and biological functions with an additional focus on potential for ghrelin-based pharmacotherapies.
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Affiliation(s)
- T R Castañeda
- Dept. of Physiology and Pharmacology, Center for Diabetes and Endocrine Research, College of Medicine, University of Toledo, Toledo, OH, USA
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Charoenthongtrakul S, Giuliana D, Longo KA, Govek EK, Nolan A, Gagne S, Morgan K, Hixon J, Flynn N, Murphy BJ, Hernández AS, Li J, Tino JA, Gordon DA, DiStefano PS, Geddes BJ. Enhanced gastrointestinal motility with orally active ghrelin receptor agonists. J Pharmacol Exp Ther 2009; 329:1178-86. [PMID: 19252061 DOI: 10.1124/jpet.108.150193] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2025] Open
Abstract
The orexigenic peptide ghrelin has been shown to have prokinetic activity in the gastrointestinal (GI) system of several species, including humans. In this series of experiments, we have evaluated the prokinetic activity of novel, small-molecule ghrelin receptor (GhrR) agonists after parenteral and peroral dosing in mice and rats. Gastric emptying, small intestinal transport, and fecal output were determined after intraperitoneal and intracerebroventricular dosing of GhrR agonists, using ghrelin as a positive control. These same parameters were evaluated after oral gavage dosing of the synthetic agonists. Regardless of dose route, GhrR agonist treatment increased gastric emptying, small intestinal transit, and fecal output. However, fecal output was only increased by GhrR agonist treatment if mice were able to feed during the stimulatory period. Thus, GhrR agonists can stimulate upper GI motility, and the orexigenic action of the compounds can indirectly contribute to prokinetic activity along the entire GI tract. The orexigenic and prokinetic effects of either ghrelin or small-molecule GhrR agonists were selective for the GhrR because they were absent when evaluated in GhrR knockout mice. We next evaluated the efficacy of the synthetic GhrR agonists dosed in a model of opiate-induced bowel dysfunction induced by a single injection of morphine. Oral dosing of a GhrR agonist normalized GI motility in opiate-induced dysmotility. These data demonstrate the potential utility of GhrR agonists for treating gastrointestinal hypomotility disorders.
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Asai S, Katabami T, Obi N, Matsui T, Kato H, Obi R, Ogawa Y, Kawata T, Takama H, Ohta A, Tanaka Y. No ghrelin response to oral glucose in diabetes mellitus with gastroparesis. Endocr J 2009; 56:79-87. [PMID: 18946177 DOI: 10.1507/endocrj.k08e-169] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
To investigate the role of ghrelin, an endogenous ligand of the growth hormone secretagogue receptor, in diabetic gastroparesis, we evaluated the plasma ghrelin profile during the oral glucose tolerance test in 55 patients with diabetes (men/women: 36/19, mean +/- SE of age: 55.1 +/- 1.7 years) with or without gastroparesis (diagnosed by the (13)C-acetate breath test). We also further examined cardiac autonomic neuropathy by assessing 24-hour variation of the R-R interval in randomly selected 32 patients with diabetes (men/women: 23/9, mean +/- SE of age: 54.2 +/- 2.5 years), and evaluated the influence of autonomic neuropathy on ghrelin. The fasting plasma ghrelin level was significantly lower in diabetes mellitus with gastroparesis than in healthy controls (7.9 +/- 0.7 fmol/ml versus 16.6 +/- 5.3 fmol/ml, p = 0.006). Patients with diabetes with gastroparesis showed no decrease of plasma ghrelin after glucose loading, unlike patients without gastroparesis or healthy controls. Diabetes mellitus with autonomic neuropathy, but not those without it, also showed no decrease of plasma ghrelin after glucose loading. Diabetic gastroparesis may be related to ghrelin-associated neurohormonal abnormalities, but the pathophysiological meaning of this abnormal ghrelin response needs further clarification.
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Affiliation(s)
- Shiko Asai
- Department of Internal Medicine, Division of Metabolism and Endocrinology, St. Marianna University School of Medicine, Kawasaki, Japan
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Taniguchi H, Ariga H, Zheng J, Ludwig K, Takahashi T. Effects of ghrelin on interdigestive contractions of the rat gastrointestinal tract. World J Gastroenterol 2008; 14:6299-302. [PMID: 19009642 PMCID: PMC2766108 DOI: 10.3748/wjg.14.6299] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [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
Ghrelin causes interdigestive contractions of the stomach in rats. However, it remains unknown whether ghrelin causes interdigestive contractions in the small intestine. Four strain gauge transducers were implanted on the antrum, duodenum, proximal and distal jejunum. After an overnight fast, gastrointestinal (GI) contractions were recorded in freely moving conscious rats. Spontaneous phase III-like contractions were observed at every 13-16 min in rat GI tract. The fasted motor patterns were replaced by the fed motor pattern immediately after food intake. Two minutes after finishing the spontaneous phase III-like contractions in the antrum, acyl ghrelin (0.8, 2.4 and 8.0 μg/kg per min) was continuously infused for 30 min. Three-five minutes after the starting ghrelin infusion, augmented phase III-like contractions were observed at the antrum, duodenum, and jejunum. Ghrelin infusion (0.8, 2.4 and 8.0 μg/kg per min) significantly increased motility index of phase III-like contractions at the antrum and jejunum in a dose dependent manner, compared to that of saline injection. Thus, it is likely that exogenously administered ghrelin causes phase III-like contraction at the antrum, which migrates to the duodenum and jejunum. The possible role of 5-HT, in addition to ghrelin, in mediating intestinal migrating motor complex (MMC), is discussed.
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Taniguchi H, Ariga H, Zheng J, Ludwig K, Mantyh C, Pappas TN, Takahashi T. Endogenous ghrelin and 5-HT regulate interdigestive gastrointestinal contractions in conscious rats. Am J Physiol Gastrointest Liver Physiol 2008; 295:G403-11. [PMID: 18566321 DOI: 10.1152/ajpgi.90260.2008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Endogenous ghrelin causes interdigestive contractions of the stomach in rats. In contrast, previous studies showed that 5-HT(3) and 5-HT(4) receptors were involved in regulating intestinal interdigestive contractions. We studied the possible role of endogenous ghrelin and 5-HT regulating interdigestive gastrointestinal (GI) contractions in rats. Four strain gauge transducers were implanted on the antrum, duodenum, and proximal and distal jejunum. After an overnight fast, GI contractions were recorded in freely moving conscious rats and ghrelin receptor antagonists [(d-lys3)GHRP6; 1 micromol/kg], 5-HT(3) antagonists (Ondansetron; 0.5 mg/kg) and 5-HT(4) antagonists (GR 125,487; 1 mg/kg) were administered (bolus iv). To evaluate the relationship between the luminal concentrations of 5-HT and phase III-like contractions of the duodenum, duodenal juice was collected via the intraduodenal catheter. 5-HT content of the duodenal juice was measured by HPLC. (d-lys3)GHRP6 significantly attenuated the occurrence and amplitude of phase III-like contractions of the antrum, but not the duodenum and jejunum. 5-HT(4) antagonists significantly reduced spontaneous phase III-like contractions of the jejunum, without affecting those of the antrum and duodenum. In contrast, 5-HT(3) antagonists did not affect phase III-like contractions in GI tract. Luminal concentration of 5-HT at the phase III-like contraction (36.0 +/- 13.3 ng/ml, n = 9) was significantly higher than that at the phase I-like contractions of the duodenum (4.9 +/- 1.6 ng/ml, n = 9, P < 0.05). It is suggested that released ghrelin from the gastric mucosa mediates gastric phase III-like contractions, whereas 5-HT released from enterochromaffin cells of the duodenal mucosa mediates intestinal phase III-like contractions via 5-HT(4) receptors.
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Affiliation(s)
- Hiroshi Taniguchi
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA
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Tümer C, Oflazoğlu HD, Obay BD, Kelle M, Taşdemir E. Effect of ghrelin on gastric myoelectric activity and gastric emptying in rats. ACTA ACUST UNITED AC 2008; 146:26-32. [PMID: 17825442 DOI: 10.1016/j.regpep.2007.07.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Accepted: 07/02/2007] [Indexed: 12/15/2022]
Abstract
Ghrelin is a recently discovered peptide in the endocrine cells of the stomach, which may stimulate gastric motility via the vagal nerve pathway. However, the mechanism of ghrelin-induced changes in gastrointestinal motility has not been clearly defined. The purpose of this study was to investigate the pharmacological effects of ghrelin on gastric myoelectrical activity and gastric emptying in rats, and to investigate whether cholinergic activity is involved in the effects of ghrelin. The study was performed on Sprague-Dawley rats implanted with serosal electrodes for electrogastrographic recording. Gastric slow waves were recorded from fasting rats at baseline and after injection of saline, ghrelin, atropine, or atropine+ghrelin. Gastric emptying of non-caloric liquid was measured by the spectrophotometric method in conscious rats. Intravenous administration of rat ghrelin (20 microg/kg) increased not only dominant frequency, dominant power and regularity of the gastric slow wave but also the gastric emptying rate when compared with the control rats (P<0.01, P<0.05, P<0.05, P<0.001 respectively). These stimulatory actions of ghrelin on both gastric myoelectrical activity and gastric emptying were not fully eliminated by pretreatment with atropine sulphate. These results taken together suggest that ghrelin may play a physiological role in the enteric neurotransmission controlling gastric contractions in rats.
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Affiliation(s)
- Cemil Tümer
- Mustafa Kemal University Medical Faculty, Department of Physiology, Hatay, Turkey
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Bibliography. Current world literature. Growth and development. Curr Opin Endocrinol Diabetes Obes 2008; 15:79-101. [PMID: 18185067 DOI: 10.1097/med.0b013e3282f4f084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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