1
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Zhang S, Kaiya H, Kitazawa T. Does ghrelin regulate intestinal motility in rabbits? An in vitro study using isolated duodenal strips. Gen Comp Endocrinol 2023; 344:114384. [PMID: 37722460 DOI: 10.1016/j.ygcen.2023.114384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/07/2023] [Accepted: 09/15/2023] [Indexed: 09/20/2023]
Abstract
Rabbit duodenum has been used for examining the ability of motilin to cause muscle contraction in vitro. A motilin-related peptide, ghrelin, is known to be involved in the regulation of gastrointestinal (GI) motility in various animals, but its ability to cause rabbit GI contraction have not been well examined. The aim of this study is to clarify the action of rat ghrelin and its interaction with motilin in the rabbit duodenum. The mRNA expression of ghrelin and motilin receptors was also examined using RT-PCR. Rat ghrelin (10-9-10-6 M) did not change the contractile activity of the duodenum measured by the mean muscle tonus and area under the curve of contraction waves. In agreement with this result, the distribution of ghrelin receptor mRNA in the rabbit GI tract varied depending on the GI region from which the samples were taken; the expression level in the duodenum was negligible, but that in the esophagus or stomach was significant. On the other hand, motilin (10-10-10-6 M) caused a concentration-dependent contraction by means of increased mean muscle tonus, and consistently, motilin receptor mRNA was expressed heterogeneously depending on the GI region (esophagus = stomach = colon = rectum < duodenum = jejunum = ileum < cecum). Expression level of motilin receptor was comparable to that of ghrelin receptor in the esophagus and stomach. Pretreatment with ghrelin (10-6 M) prior to motilin did not affect the contractile activity of motilin in the duodenum. In conclusion, ghrelin does not affect muscle contractility or motilin-induced contraction in the rabbit duodenum, which is due to the lack of ghrelin receptors. The present in vitro results suggest that ghrelin might not be a regulator of intestinal motility in rabbits.
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Affiliation(s)
- Shuangyi Zhang
- Laboratory of Veterinary Physiology, College of Veterinary Medicine, Inner Mongolia Agricultural University, Hohhot 010018, China; School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Hiroyuki Kaiya
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka 564-8565, Japan; Faculty of Science, University of Toyama, Toyama, Toyama 933-8555, Japan; Grandsoul Research Institute for Immunology, Inc., Uda, Nara 633-2221, Japan
| | - Takio Kitazawa
- School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan.
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2
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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] [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 Research, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
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3
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Zhang S, Kaiya H, Teraoka H, Kitazawa T. Pheasant motilin, its distribution and gastrointestinal contractility-stimulating action in the pheasant. Gen Comp Endocrinol 2021; 314:113897. [PMID: 34506789 DOI: 10.1016/j.ygcen.2021.113897] [Citation(s) in RCA: 1] [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: 06/24/2021] [Revised: 08/17/2021] [Accepted: 09/01/2021] [Indexed: 11/16/2022]
Abstract
Previously, pheasant motilin was identified as a 22-amino acid peptide with a sequence of FVPFFTQSDI QKMQEKERIK GQ. In the present study, the distribution of pheasant motilin mRNA was determined and compared with that of ghrelin, a motilin-related peptide. The effects of pheasant motilin on the cognate gastrointestinal (GI) muscle strips were also examined in an in vitro contraction study. The expression of pheasant motilin mRNA was highest in the small intestine (duodenum, jejunum and ileum), moderate in the colon and very low in the brain, lung, heart, pancreas, esophagus, proventriculus, gizzard and caecum, and this distribution was in contrast with that of ghrelin mRNA. Pheasant motilin caused contraction of the cognate GI tract in a region-dependent manner, similar to chicken motilin. The contraction in the small intestine was large and was not affected by atropine. In contrast, contraction in the proventriculus was small and was decreased by atropine. The crop and colon were insensitive to pheasant motilin. Neither GM109 nor MA2029, mammalian motilin receptor antagonists inhibited the contractions of pheasant motilin. Erythromycin was ineffective in the pheasant ileum, although it caused contraction of the rabbit duodenum. These results indicate that pheasant motilin caused contraction through an action on smooth muscles in the small intestine and an action on enteric cholinergic nerves in the proventriculus. This high responsiveness of the small intestine suggests that motilin is a regulator of small intestinal motility in avians, and the characteristic of the motilin receptor in the pheasant might be different from that in mammals, as is that in chickens.
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Affiliation(s)
- Shuangyi Zhang
- School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Hiroyuki Kaiya
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka 565-8565, Japan
| | - Hiroki Teraoka
- School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Takio Kitazawa
- School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan.
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4
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Li H, Yang L, Jin Y, Jin C. Roles of Endothelial Motilin Receptor and Its Signal Transduction Pathway in Motilin-Induced Left Gastric Artery Relaxation in Dogs. Front Physiol 2021; 12:770430. [PMID: 34777026 PMCID: PMC8581264 DOI: 10.3389/fphys.2021.770430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 10/05/2021] [Indexed: 12/04/2022] Open
Abstract
Background: Motilin increases left gastric artery (LGA) blood flow in dogs via the endothelial motilin receptor (MLNR). This article investigates the signaling pathways of endothelial MLNR. Methods: Motilin-induced relaxation of LGA rings was assessed using wire myography. Nitric oxide (NO), and cyclic guanosine monophosphate (cGMP) levels were measured using an NO assay kit and cGMP ELISA kit, respectively. Results: Motilin concentration-dependently (EC50=9.1±1.2×10−8M) relaxed LGA rings precontracted with U46619 (thromboxane A2 receptor agonist). GM-109 (MLNR antagonist) significantly inhibited motilin-induced LGA relaxation and the production of NO and cGMP. N-ethylmaleimide (NEM; G-protein antagonist), U73122 [phospholipase C (PLC) inhibitor], and 2-aminoethyl diphenylborinate [2-APB; inositol trisphosphate (IP3) blocker] partially or completely blocked vasorelaxation. In contrast, chelerythrine [protein kinase C (PKC) inhibitor] and H89 [protein kinase A (PKA) inhibitor] had no such effect. Low-calcium or calcium-free Krebs solutions also reduced vasorelaxation. N-nitro-L-arginine methyl ester [L-NAME; nitric oxide synthase (NOS) inhibitor] and ODQ [soluble guanylyl cyclase (sGC) inhibitor] completely abolished vasodilation and synthesis of NO and cGMP. Indomethacin (cyclooxygenase inhibitor), 18α-glycyrrhetinic acid [18α-GA; myoendothelial gap junction (MEGJ) inhibitor], and K+ channel inhibition through high K+ concentrations or tetraethylammonium (TEA-Cl; KCa channel blocker) partially decreased vasorelaxation, whereas glibenclamide (KATP channel blocker) had no such effect. Conclusion: The current study suggests that motilin-induced LGA relaxation is dependent on endothelial MLNR through the G protein-PLC-IP3 pathway and Ca2+ influx. The NOS-NO-sGC-cGMP pathway, prostacyclin, MEGJ, and K+ channels (especially KCa) are involved in endothelial-dependent relaxation of vascular smooth muscle (VSM) cells.
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Affiliation(s)
- HongYu Li
- Department of Ultrasound, China-Japan Union Hospital of Jilin University, Changchun, China.,Department of Ultrasound, The First Hospital of Jilin University, Changchun, China
| | - LanLan Yang
- Department of Ultrasound, China-Japan Union Hospital of Jilin University, Changchun, China.,Department of Hepatopancreatobiliary Medicine, The Second Hospital of Jilin University, Changchun, China
| | - Ying Jin
- Department of Breast Surgery, The First Hospital of Jilin University, Changchun, China
| | - ChunXiang Jin
- Department of Ultrasound, China-Japan Union Hospital of Jilin University, Changchun, China
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Yang L, Li H, Jin Y, He Y, Mei L, Jin C. Differential expression of motilin receptors on the endothelium of dog gastrointestinal arteries and motilin-induced motilin receptor dependent relaxation of corresponding arteries. Peptides 2021; 143:170574. [PMID: 34082070 DOI: 10.1016/j.peptides.2021.170574] [Citation(s) in RCA: 1] [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: 02/19/2021] [Revised: 05/09/2021] [Accepted: 05/14/2021] [Indexed: 12/14/2022]
Abstract
BACKGROUND Motilin's role in the regulation of vascular tone and hemodynamic besides gastrointestinal motility is concerned. This study aimed to investigate the expression of motilin receptors in gastrointestinal arteries and motilin-induced relaxation. MATERIAL AND METHODS The expression of motilin receptors in the left gastric artery (LGA), superior mesenteric artery (SMA), and inferior mesenteric artery (IMA) of adult dogs (1.5-5 years old) were analyzed by immunochemistry, RT-PCR, and western blotting. Motilin's effects on the gastrointestinal arteries were evaluated in a multi-wire myograph system. RESULTS Immunohistochemical staining showed that motilin receptor was expressed on the membranes of endothelial cells with the fluorescence intensity LGA > SMA > IMA (P < 0.01). The motilin receptor's mRNA and protein expression levels shared the same distribution patterns as it in fluorescence intensity (P < 0.01). In isolated LGA preparations precontracted with U46619 (a thromboxaneA2 analog), motilin induced a concentration-dependent relaxation, and the EC50 was 8.8 × 10-8 ± 0.9 × 10-8 M. Motilin-induced relaxation on the three arteries also shared the same pattern as it in fluorescence intensity (P < 0.01) and inhibited by denuded-endothelium and GM-109 (a motilin receptor antagonist) but not by atropine (a muscarinic receptor antagonist). CONCLUSIONS Motilin receptors are expressed differentially on the membranes of endothelial cells in dog gastrointestinal arteries with a significantly high expression in the LGA. Motilin-induced relaxation is endothelium- and motilin receptor-dependent. The motilin receptor expressed on the endothelial cell membrane of the LGA is the molecular basis for motilin regulating gastric blood flow under physiological conditions in dogs.
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Affiliation(s)
- Lanlan Yang
- Department of Ultrasound, China-Japan Union Hospital of Jilin University, Changchun, China; Department of Hepatopancreatobiliary Medicine, The Second Hospital of Jilin University, Changchun, China
| | - Hongyu Li
- Department of Ultrasound, China-Japan Union Hospital of Jilin University, Changchun, China; Department of Ultrasound, The First Hospital of Jilin University, Changchun, China
| | - Ying Jin
- Department of Breast Surgery, The First Hospital of Jilin University, Changchun, China
| | - Yu He
- Department of Ultrasound, China-Japan Union Hospital of Jilin University, Changchun, China
| | - Li Mei
- Department of Ultrasound, China-Japan Union Hospital of Jilin University, Changchun, China; Department of Ultrasound, The First Hospital of Jilin University, Changchun, China
| | - Chunxiang Jin
- Department of Ultrasound, China-Japan Union Hospital of Jilin University, Changchun, China.
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6
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Kitazawa T, Kaiya H. Motilin Comparative Study: Structure, Distribution, Receptors, and Gastrointestinal Motility. Front Endocrinol (Lausanne) 2021; 12:700884. [PMID: 34497583 PMCID: PMC8419268 DOI: 10.3389/fendo.2021.700884] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/16/2021] [Indexed: 12/26/2022] Open
Abstract
Motilin, produced in endocrine cells in the mucosa of the upper intestine, is an important regulator of gastrointestinal (GI) motility and mediates the phase III of interdigestive migrating motor complex (MMC) in the stomach of humans, dogs and house musk shrews through the specific motilin receptor (MLN-R). Motilin-induced MMC contributes to the maintenance of normal GI functions and transmits a hunger signal from the stomach to the brain. Motilin has been identified in various mammals, but the physiological roles of motilin in regulating GI motility in these mammals are well not understood due to inconsistencies between studies conducted on different species using a range of experimental conditions. Motilin orthologs have been identified in non-mammalian vertebrates, and the sequence of avian motilin is relatively close to that of mammals, but reptile, amphibian and fish motilins show distinctive different sequences. The MLN-R has also been identified in mammals and non-mammalian vertebrates, and can be divided into two main groups: mammal/bird/reptile/amphibian clade and fish clade. Almost 50 years have passed since discovery of motilin, here we reviewed the structure, distribution, receptor and the GI motility regulatory function of motilin in vertebrates from fish to mammals.
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Affiliation(s)
- Takio Kitazawa
- Comparative Animal Pharmacology, Department of Veterinary Science, Rakuno Gakuen University, Ebetsu, Japan
| | - Hiroyuki Kaiya
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
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Singaram K, Gold-Smith FD, Petrov MS. Motilin: a panoply of communications between the gut, brain, and pancreas. Expert Rev Gastroenterol Hepatol 2020; 14:103-111. [PMID: 31996050 DOI: 10.1080/17474124.2020.1718492] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Introduction: Motilin was first alluded to nearly a century ago. But it remains a rather abstruse peptide, in the shadow of its younger but more lucid 'cousin' ghrelin.Areas covered: The review aimed to bring to the fore multifarious aspects of motilin research with a view to aiding prioritization of future studies on this gastrointestinal peptide.Expert opinion: Growing evidence indicates that rodents (mice, rats, guinea pigs) do not have functional motilin system and, hence, studies in these species are likely to have a minimal translational impact. Both the active peptide and motilin receptor were initially localized to the upper gastrointestinal tract only but more recently - also to the brain (in both humans and other mammals with functional motilin system). Motilin is now indisputably implicated in interdigestive contractile activity of the gastrointestinal tract (in particular, gastric phase III of the migrating motor complex). Beyond this role, evidence is building that there is a cross-talk between motilin system and the brain-pancreas axis, suggesting that motilin exerts not only contractile but also orexigenic and insulin secretagogue actions.
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Affiliation(s)
| | | | - Maxim S Petrov
- School of Medicine, University of Auckland, Auckland, New Zealand
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Zhang S, Okuhara Y, Iijima M, Takemi S, Sakata I, Kaiya H, Teraoka H, Kitazawa T. Identification of pheasant ghrelin and motilin and their actions on contractility of the isolated gastrointestinal tract. Gen Comp Endocrinol 2020; 285:113294. [PMID: 31585115 DOI: 10.1016/j.ygcen.2019.113294] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 09/02/2019] [Accepted: 09/29/2019] [Indexed: 12/11/2022]
Abstract
Motilin and ghrelin were identified in the pheasant by molecular cloning, and the actions of both peptides on the contractility of gastrointestinal (GI) strips were examined in vitro. Molecular cloning indicated that the deduced amino acid sequences of the pheasant motilin and ghrelin were a 22-amino acid peptide, FVPFFTQSDIQKMQEKERIKGQ, and a 26-amino acid peptide, GSSFLSPAYKNIQQQKDTRKPTGRLH, respectively. In in vitro studies using pheasant GI strips, chicken motilin caused contraction of the proventriculus and small intestine, whereas the crop and colon were insensitive. Human motilin, but not erythromycin, caused contraction of small intestine. Chicken motilin-induced contractions in the proventriculus and ileum were not inhibited by a mammalian motilin receptor antagonist, GM109. Neither atropine (a cholinergic receptor antagonist) nor tetrodotoxin (a neuron blocker) inhibited the responses of chicken motilin in the ileum but both drugs decreased the responses to motilin in the proventriculus, suggesting that the contractile mechanisms of motilin in the proventriculus was neurogenic, different from that of the small intestine (myogenic). On the other hand, chicken and quail ghrelin did not cause contraction in any regions of pheasant GI tract. Since interaction of ghrelin and motilin has been reported in the house musk shrew, interaction of two peptides was examined. The chicken motilin-induced contractions were not modified by ghrelin, and ghrelin also did not cause any contraction under the presence of motilin, suggesting the absence of interaction in both peptides. In conclusion, both the motilin system and ghrelin system are present in the pheasant. Regulation of GI motility by motilin might be common in avian species. However, absence of ghrelin actions in any GI regions suggests the avian species-related difference in regulation of GI contractility by ghrelin.
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Affiliation(s)
- Shuangyi Zhang
- Department of Veterinary Science, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan; School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Yuji Okuhara
- School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Mio Iijima
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Shota Takemi
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Ichiro Sakata
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Hiroyuki Kaiya
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka 565-8565, Japan
| | - Hiroki Teraoka
- School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Takio Kitazawa
- Department of Veterinary Science, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan.
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Liu D, Han R, Wang X, Li W, Tang S, Li W, Wang Y, Jiang R, Yan F, Wang C, Liu X, Kang X, Li Z. A novel 86-bp indel of the motilin receptor gene is significantly associated with growth and carcass traits in Gushi-Anka F 2 reciprocal cross chickens. Br Poult Sci 2019; 60:649-658. [PMID: 31469320 DOI: 10.1080/00071668.2019.1655710] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
1. A previous whole-genome association analysis has identified the motilin receptor gene (MLNR), which regulates gastrointestinal motility and gastric emptying, as a candidate gene related to chicken growth.2. MLNR mRNA was expressed in all tissues tested, and the expression level in digestive tissues was greater than in other tissues. Expression levels in the pancreas, duodenum and glandular stomach at day old and one, two and three weeks of age indicated a possible correlation with the digestive system. This suggested that the MLNR gene plays a central role in gastrointestinal tract function and affects the growth and development of chickens. Moreover, there was a significant difference in expression in the glandular stomach tissue between Ross 308 and Gushi chickens at six weeks of age.3. Re-sequencing revealed an 86-bp insertion/deletion polymorphism in the downstream region of the MLNR gene. The mutation locus was genotyped in 2,261 individuals from nine different chicken breeds. MLNR expression levels in the glandular stomach of chickens with DD genotypes were greater than those in chickens with the ID and II genotypes. The DD genotype was the most dominant genotype in commercial broiler's (Ross 308 and Arbor Acres broilers), and the D allele frequency in these breeds exceeded 91%. The deletion mutation tended towards fixation in commercial broilers.4. Association with growth and carcass traits analysed in a Gushi-Anka F2 intercrossed population, showed that the DD genotype was significantly associated with the greatest growth and carcass trait values, whereas values associated with the II genotype were the lowest in the F2 reciprocal cross chickens.5. The results suggest that the mutation is strongly associated with growth related traits and it is likely to be useful for marker-assisted selection of chickens.
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Affiliation(s)
- D Liu
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
| | - R Han
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
| | - X Wang
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
| | - W Li
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
| | - S Tang
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Zhengzhou, Henan, China
| | - W Li
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
| | - Y Wang
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
| | - R Jiang
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
| | - F Yan
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
| | - C Wang
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
| | - X Liu
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
| | - X Kang
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
| | - Z Li
- College of Animal Science and Veterinary Medicine, Henan Agricultural University, Henan Innovative Engineering Research Center of Poultry Germplasm Resource, Zhengzhou, Henan, China
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Zhou Y, Qi X, Wen H, Zhang K, Zhang X, Li J, Li Y, Fan H. Identification, expression analysis, and functional characterization of motilin and its receptor in spotted sea bass (Lateolabrax maculatus). Gen Comp Endocrinol 2019; 277:38-48. [PMID: 30771290 DOI: 10.1016/j.ygcen.2019.02.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 01/08/2019] [Accepted: 02/11/2019] [Indexed: 12/28/2022]
Abstract
Motilin (MLN), an interdigestive hormone secreted by endocrine cells of the intestinal mucosa, binds to a G protein-coupled receptor to exert its biological function of regulating gastrointestinal motility. In the present study, we identified the prepromotilin and mln receptor (mlnr) from the spotted sea bass, Lateolabrax maculatus. Mln consisted of an ORF of 336 nucleotides encoding 111 amino acids. The precursor protein contained a 17-amino-acid mature peptide. Mlnr had an ORF of 1089 bp encoding a protein of 362 amino acids. Seven transmembrane domains were predicted with TMHMM analysis. The phylogenetic analysis of mln and mlnr showed that they fell into the same clade with respective counterpart of selected fishes before clustering with other detected vertebrates. Both mln and mlnr genes were highly expressed in intestine of spotted sea bass using quantitative real-time PCR. In situ hybridization indicated that mln and mlnr mRNA were both localized in the lamina propria and the epithelial cell of intestinal villus. The expressions of both genes were regulated under short-term starvation in a time-dependent manner. In vitro experiments indicated that the expressions of ghrelin (ghrl), gastrin (gas) and cholecystokinin (cck) were enhanced by MLN after 3-h treatment, but the effect was absent after 6 or 12-h incubation. Taken together, the MLN and its receptor might play important roles in regulating intestinal motility in spotted sea bass.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Bass/genetics
- Cloning, Molecular
- Fasting
- Gene Expression Profiling
- Gene Expression Regulation
- Intestines/cytology
- Molecular Docking Simulation
- Motilin/chemistry
- Motilin/genetics
- Motilin/metabolism
- Phylogeny
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Gastrointestinal Hormone/chemistry
- Receptors, Gastrointestinal Hormone/genetics
- Receptors, Gastrointestinal Hormone/metabolism
- Receptors, Neuropeptide/chemistry
- Receptors, Neuropeptide/genetics
- Receptors, Neuropeptide/metabolism
- Sequence Analysis, DNA
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Affiliation(s)
- Yangyang Zhou
- Key Laboratory of Mariculture (Ocean University of China), Ministry of Education, Qingdao, 266003, PR China
| | - Xin Qi
- Key Laboratory of Mariculture (Ocean University of China), Ministry of Education, Qingdao, 266003, PR China
| | - Haishen Wen
- Key Laboratory of Mariculture (Ocean University of China), Ministry of Education, Qingdao, 266003, PR China
| | - Kaiqiang Zhang
- Key Laboratory of Mariculture (Ocean University of China), Ministry of Education, Qingdao, 266003, PR China
| | - Xiaoyan Zhang
- Key Laboratory of Mariculture (Ocean University of China), Ministry of Education, Qingdao, 266003, PR China
| | - Jin Li
- Ji'nan Aquatic Technology Extension Station, Ji'nan 250021, China
| | - Yun Li
- Key Laboratory of Mariculture (Ocean University of China), Ministry of Education, Qingdao, 266003, PR China.
| | - Hongying Fan
- Key Laboratory of Mariculture (Ocean University of China), Ministry of Education, Qingdao, 266003, PR China.
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Deloose E, Verbeure W, Depoortere I, Tack J. Motilin: from gastric motility stimulation to hunger signalling. Nat Rev Endocrinol 2019; 15:238-250. [PMID: 30675023 DOI: 10.1038/s41574-019-0155-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
After the discovery of motilin in 1972, motilin and the motilin receptor were studied intensely for their role in the control of gastrointestinal motility and as targets for treating hypomotility disorders. The genetic revolution - with the use of knockout models - sparked novel insights into the role of multiple peptides but contributed to a decline in interest in motilin, as this peptide and its receptor exist only as pseudogenes in rodents. The past 5 years have seen a major surge in interest in motilin, as a series of studies have shown its relevance in the control of hunger and regulation of food intake in humans in both health and disease. Luminal stimuli, such as bitter tastants, have been identified as modulators of motilin release, with effects on hunger and food intake. The current state of knowledge and potential implications for therapy are summarized in this Review.
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Affiliation(s)
- Eveline Deloose
- Translational Research in Gastrointestinal Disorders (TARGID), Department of Chronic Diseases, Metabolism and Ageing (CHROMETA), KU Leuven, Leuven, Belgium
| | - Wout Verbeure
- Translational Research in Gastrointestinal Disorders (TARGID), Department of Chronic Diseases, Metabolism and Ageing (CHROMETA), KU Leuven, Leuven, Belgium
| | - Inge Depoortere
- Translational Research in Gastrointestinal Disorders (TARGID), Department of Chronic Diseases, Metabolism and Ageing (CHROMETA), KU Leuven, Leuven, Belgium
| | - Jan Tack
- Translational Research in Gastrointestinal Disorders (TARGID), Department of Chronic Diseases, Metabolism and Ageing (CHROMETA), KU Leuven, Leuven, Belgium.
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Kitazawa T, Harada R, Sakata I, Sakai T, Kaiya H. A verification study of gastrointestinal motility-stimulating action of guinea-pig motilin using isolated gastrointestinal strips from rabbits and guinea-pigs. Gen Comp Endocrinol 2019; 274:106-112. [PMID: 30677392 DOI: 10.1016/j.ygcen.2019.01.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 01/07/2019] [Accepted: 01/17/2019] [Indexed: 12/13/2022]
Abstract
Motilin (MLN), a 22-amino-acid peptide hormone, is generally present in the mucosa of the upper gastrointestinal (GI) tract, mainly the duodenum of mammals, and it regulates GI motility, especially that related to interdigestive migrating contraction. However, MLN and its receptor are absent in mice and rats, and MLN does not cause any mechanical responses in the rat and mouse GI tracts. The guinea-pig is also a rodent, but expression of the MLN gene in the guinea-pig has been reported. In the present study, two guinea-pig MLNs, FIPIFTYSELRRTQEREQNKGL found in the Ensemble Genome Database (gpMLN-1) and FVPIFTYSELRRTQEREQNKRL reported by Xu et al. (2001) (gpMLN-2), were synthesized, and their biological activities were evaluated in the rabbit duodenum and guinea-pig GI tract in vitro. Both gpMLNs showed contractile activity in longitudinal muscle strips of the rabbit duodenum. The EC50 values of gpMLN-1 and gpMLN-2 were slightly higher than that of human MLN (hMLN), but the maximum contractions were as same as that of hMLN. Treatment with GM109 and hMLN-induced receptor desensitization decreased the contractile activity of both gpMLNs, indicating that the two gpMLN candidates are able to activate the MLN receptor (MLN-R) of the rabbit duodenum. In guinea-pig GI preparations, hMLN and gpMLNs did not show any mechanical responses in circular muscle strips from the gastric antrum or in longitudinal strips of the duodenum, ileum and colon although acetylcholine and 1,1-dimethyl-4-phenylpiperazinium (DMPP) caused definite mechanical responses. The DMPP-induced neural responses in the gastric circular muscle and ileal longitudinal muscles were not modified by gpMLN-1. Even in the gastric and ileal strips with intact mucosa, no mechanical responses were seen with either of the gpMLNs. Furthermore, RT-PCR using various primer sets failed to amplify the gpMLN-2 mRNA. In conclusion, gpMLNs including one that was already reported and the other that was newly found in a database were effective to the rabbit MLN-R, whereas they did not cause any contractions or modification of neural responses in the guinea-pig GI tract, indicating that the MLN system is vestigial and not functional in regulation of GI motility in the guinea-pig as well as in other rodents such as rats and mice.
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Affiliation(s)
- Takio Kitazawa
- Department of Veterinary Science, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan.
| | - Rio Harada
- Department of Veterinary Science, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Ichiro Sakata
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Takafumi Sakai
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Hiroyuki Kaiya
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka 565-8565, Japan
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13
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Kawamura T, Matsuura B, Miyake T, Abe M, Ikeda Y, Hiasa Y. Effects of Motilin Receptor Agonists and Ghrelin in Human motilin receptor Transgenic Mice. Int J Mol Sci 2019; 20:ijms20071521. [PMID: 30934667 PMCID: PMC6479874 DOI: 10.3390/ijms20071521] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/23/2019] [Accepted: 03/24/2019] [Indexed: 12/13/2022] Open
Abstract
Gastrointestinal motility is regulated by neural factors and humoral factors. Both motilin and ghrelin improve gastrointestinal motility, but many issues remain unclear. We prepared human motilin receptor transgenic (Tg) mice and performed experiments evaluating the effects of motilin, erythromycin (EM), and ghrelin. EM and ghrelin promoted gastric emptying (GE) when administered either peripherally or centrally to Tg mice. Atropine (a muscarinic receptor antagonist) counteracted GE induced by centrally administered EM, but not that induced by peripherally administered EM. The administration of EM in this model promoted the effect of mosapride (a selective serotonin 5-hydroxytryptamine 4 (5-HT4) receptor agonist), and improved loperamide (a μ-opioid receptor agonist)-induced gastroparesis. The level of acyl-ghrelin was significantly attenuated by EM administration. Thus, we have established an animal model appropriate for the evaluation of motilin receptor agonists. These data and the model are expected to facilitate the identification of novel compounds with clinical potential for relieving symptoms of dyspepsia and gastroparesis.
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MESH Headings
- Animals
- Benzamides/pharmacology
- Erythromycin/administration & dosage
- Erythromycin/pharmacology
- Gastric Emptying/drug effects
- Gastroparesis/blood
- Gastroparesis/chemically induced
- Gastroparesis/drug therapy
- Gastroparesis/physiopathology
- Ghrelin/blood
- Ghrelin/pharmacology
- Humans
- Loperamide/adverse effects
- Male
- Mice, Inbred C57BL
- Mice, Transgenic
- Morpholines/pharmacology
- Postprandial Period
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Gastrointestinal Hormone/agonists
- Receptors, Gastrointestinal Hormone/genetics
- Receptors, Gastrointestinal Hormone/metabolism
- Receptors, Ghrelin/genetics
- Receptors, Ghrelin/metabolism
- Receptors, Neuropeptide/agonists
- Receptors, Neuropeptide/genetics
- Receptors, Neuropeptide/metabolism
- Stomach/drug effects
- Stomach/pathology
- Stomach/physiopathology
- Vagus Nerve/drug effects
- Vagus Nerve/physiology
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Affiliation(s)
- Tomoe Kawamura
- Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Toon City 791-0295, Japan.
| | - Bunzo Matsuura
- Department of Lifestyle-related Medicine and Endocrinology, Ehime University Graduate School of Medicine, Toon City 791-0295, Japan.
| | - Teruki Miyake
- Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Toon City 791-0295, Japan.
| | - Masanori Abe
- Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Toon City 791-0295, Japan.
| | - Yoshiou Ikeda
- Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Toon City 791-0295, Japan.
| | - Yoichi Hiasa
- Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Toon City 791-0295, Japan.
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Kato S, Takahashi A, Shindo M, Yoshida A, Kawamura T, Matsumoto K, Matsuura B. Characterization of the gastric motility response to human motilin and erythromycin in human motilin receptor-expressing transgenic mice. PLoS One 2019; 14:e0205939. [PMID: 30789939 PMCID: PMC6383879 DOI: 10.1371/journal.pone.0205939] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 02/06/2019] [Indexed: 12/27/2022] Open
Abstract
Motilin is a gastrointestinal peptide hormone that stimulates gastrointestinal motility. Motilin is produced primarily in the duodenum and jejunum. Motilin receptors (MTLRs) are G protein-coupled receptors that may represent a clinically useful pharmacological target as they can be activated by erythromycin. The functions of motilin are highly species-dependent and remain poorly understood. As a functional motilin system is absent in rodents such as rats and mice, these species are not commonly used for basic studies. In this study, we examine the usefulness of human MTLR-overexpressing transgenic (hMTLR-Tg) mice by identifying the mechanisms of the gastric motor response to human motilin and erythromycin. The distribution of hMTLR was examined immunohistochemically in male wild-type (WT) and hMTLR-Tg mice. The contractile response of gastric strips was measured isometrically in an organ bath, while gastric emptying was determined using phenol red. hMTLR expression was abundant in the gastric smooth muscle layer. Interestingly, higher levels of hMTLR expression were observed in the myenteric plexus of hMTLR-Tg mice but not WT mice. hMTLR was not co-localized with vesicular acetylcholine transporter, a marker of cholinergic neurons in the myenteric plexus. Treatment with human motilin and erythromycin caused concentration-dependent contraction of gastric strips obtained from hMTLR-Tg mice but not from WT mice. The contractile response to human motilin and erythromycin in hMTLR-Tg mice was affected by neither atropine nor tetrodotoxin and was totally absent in Ca2+-free conditions. Furthermore, intraperitoneal injection of erythromycin significantly promoted gastric emptying in hMTLR-Tg mice but not in WT mice. Human motilin and erythromycin stimulate gastric smooth muscle contraction in hMTLR-Tg mice. This action is mediated by direct contraction of smooth muscle via the influx of extracellular Ca2+. Thus, hMTLR-Tg mice may be useful for the evaluation of MTLR agonists as gastric prokinetic agents.
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Affiliation(s)
- Shinichi Kato
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Misasagi, Yamashina, Kyoto, Japan
- * E-mail:
| | - Aoi Takahashi
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Misasagi, Yamashina, Kyoto, Japan
| | - Mai Shindo
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Misasagi, Yamashina, Kyoto, Japan
| | - Ayano Yoshida
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Misasagi, Yamashina, Kyoto, Japan
| | - Tomoe Kawamura
- Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
| | - Kenjiro Matsumoto
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Misasagi, Yamashina, Kyoto, Japan
| | - Bunzo Matsuura
- Department of Lifestyle-related Medicine and Endocrinology, Ehime University Graduate School of Medicine, Toon, Ehime, Japan
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15
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Kitazawa T, Kaiya H. Regulation of Gastrointestinal Motility by Motilin and Ghrelin in Vertebrates. Front Endocrinol (Lausanne) 2019; 10:278. [PMID: 31156548 PMCID: PMC6533539 DOI: 10.3389/fendo.2019.00278] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 04/16/2019] [Indexed: 12/14/2022] Open
Abstract
The energy balance of vertebrates is regulated by the difference in energy input and energy expenditure. Generally, most vertebrates obtain their energy from nutrients of foods through the gastrointestinal (GI) tract. Therefore, food intake and following food digestion, including motility of the GI tract, secretion and absorption, are crucial physiological events for energy homeostasis. GI motility changes depending on feeding, and GI motility is divided into fasting (interdigestive) and postprandial (digestive) contraction patterns. GI motility is controlled by contractility of smooth muscles of the GI tract, extrinsic and intrinsic neurons (motor and sensory) and some hormones. In mammals, ghrelin (GHRL) and motilin (MLN) stimulate appetite and GI motility and contribute to the regulation of energy homeostasis. GHRL and MLN are produced in the mucosal layer of the stomach and upper small intestine, respectively. GHRL is a multifunctional peptide and is involved in glucose metabolism, endocrine/exocrine functions and cardiovascular and reproductive functions, in addition to feeding and GI motility in mammals. On the other hand, the action of MLN is restricted and species such as rodentia, including mice and rats, lack MLN peptide and its receptor. From a phylogenetic point of view, GHRL and its receptor GHS-R1a have been identified in various vertebrates, and their structural features and various physiological functions have been revealed. On the other hand, MLN or MLN-like peptide (MLN-LP) and its receptors have been found only in some fish, birds and mammals. Here, we review the actions of GHRL and MLN with a focus on contractility of the GI tract of species from fish to mammals.
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Affiliation(s)
- Takio Kitazawa
- Comparative Animal Pharmacology, Department of Veterinary Science, Rakuno Gakuen University, Ebetsu, Japan
- *Correspondence: Takio Kitazawa
| | - Hiroyuki Kaiya
- Department of Biochemistry, National Cerebral and Cardiovascular Center Research Institute, Suita, Japan
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16
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Deloose E, Biesiekierski JR, Vanheel H, Depoortere I, Tack J. Effect of motilin receptor activation on food intake and food timing. Am J Clin Nutr 2018; 107:537-543. [PMID: 29635488 DOI: 10.1093/ajcn/nqx044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 11/20/2017] [Indexed: 12/17/2022] Open
Abstract
Background Motilin plasma concentrations are positively correlated with hunger ratings during the fasting state. Moreover, the motilin agonist erythromycin stimulates meal requests. Objectives The first aim of the study was to evaluate the effect of erythromycin on ad libitum food intake. The second aim was to study the involvement of endogenous motilin and octanoylated ghrelin on voluntary meal initiations. Design Study 1: Fourteen healthy participants were studied twice after an overnight fast. Intravenous administration of placebo (saline) or erythromycin (40 mg) was given in a double-blind randomized order. Participants had the opportunity to eat ad libitum from an excess free-choice buffet (2330 kcal) for the duration of 1 h. The primary outcome was total caloric intake. Study 2: Thirteen healthy participants were studied after an overnight fast. Baseline blood samples were collected before a breakfast (245 kcal). After a rest period of 90 min, blood samples were collected every 15 min for a duration of 5 h. During this period, volunteers could request small meal portions (164 kcal/serving) at time points of their choosing and unlimited in numbers. The primary outcome was the determination of plasma concentrations before postbreakfast spontaneous meal requests. Results Ad libitum food intake did not differ between placebo and erythromycin groups (difference compared with placebo: 79 kcal; 95% CI: -245.9, 403.97 kcal; P = 0.3). Octanoylated ghrelin concentrations before spontaneous meal requests were, on average, 36% (95% CI: 5.8%, 65.7%; P = 0.02) higher than values before breakfast, whereas motilin concentrations did not increase (6% increase: 95% CI: -5.9%, 17.2% increase; P = 0.3). Conclusions Motilin receptor stimulation during the fasting state does not affect total caloric intake nor does endogenous motilin stimulate meal requests after breakfast in the current study population. This trial was registered at www.clinicaltrials.gov as NCT03024879.
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Affiliation(s)
- Eveline Deloose
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Jessica R Biesiekierski
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Hanne Vanheel
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Inge Depoortere
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
| | - Jan Tack
- Translational Research Center for Gastrointestinal Disorders, University of Leuven, Leuven, Belgium
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17
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Abstract
Ghrelin and motilin are released from gastrointestinal endocrine cells during hunger, to act through G protein-coupled receptors that have closely related amino acid sequences. The actions of ghrelin are more complex than motilin because ghrelin also exists outside the GI tract, it is processed to des-acyl ghrelin which has activity, ghrelin can exist in truncated forms and retain activity, the ghrelin receptor can have constitutive activity and is subject to biased agonism and finally additional ghrelin-like and des-acyl ghrelin receptors are proposed. Both ghrelin and motilin can stimulate gastric emptying, acting via different pathways, perhaps influenced by biased agonism at the receptors, but research is revealing additional pathways of activity. For example, it is becoming apparent that reduction of nausea may be a key therapeutic target for ghrelin receptor agonists and perhaps for compounds that modulate the constitutive activity of the ghrelin receptor. Reduction of nausea may be the mechanism through which gastroparesis symptoms are reduced. Intriguingly, a potential ability of motilin to influence nausea is also becoming apparent. Ghrelin interacts with digestive function through its effects on appetite, and ghrelin antagonists may have a place in treating Prader-Willi syndrome. Unlike motilin, ghrelin receptor agonists also have the potential to treat constipation by acting at the lumbosacral defecation centres. In conclusion, agonists of both ghrelin and motilin receptors hold potential as treatments for specific subsets of digestive system disorders.
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18
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Molecular Ghrelin System in the Pancreatic Acinar Cells: The Role of the Polypeptide, Caerulein and Sensory Nerves. Int J Mol Sci 2017; 18:ijms18050929. [PMID: 28468316 PMCID: PMC5454842 DOI: 10.3390/ijms18050929] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/09/2017] [Accepted: 04/19/2017] [Indexed: 12/25/2022] Open
Abstract
Ghrelin (GHRL) is an endogenous ligand for the growth hormone secretagogue receptor (GHS-R). Experimental studies showed that GHRL protects the stomach and pancreas against acute damage, but the effect of GHRL on pancreatic acinar cells was still undetermined. Aim: To investigate the effect of GHRL and caerulein on the functional ghrelin system in pancreatic acinar cells taking into account the role of sensory nerves (SN). Methods: Experiments were carried out on isolated pancreatic acinar cells and AR42J cells. Before acinar cells isolation, GHRL was administered intraperitoneally at a dose of 50 µg/kg to rats with intact SN or with capsaicin deactivation of SN (CDSN). After isolation, pancreatic acinar cells were incubated in caerulein-free or caerulein containing solution. AR42J cells were incubated under basal conditions and stimulated with caerulein, GHRL or a combination of the above. Results: Incubation of isolated acinar cells with caerulein inhibited GHS-R and GHRL expression at the level of mRNA and protein in those cells. Either in rats with intact SN or with CDSN, administration of GHRL before isolation of acinar cells increased expression of GHRL and GHS-R in those cells and reversed the caerulein-induced reduction in expression of those parameters. Similar upregulation of GHS-R and GHRL was observed after administration of GHRL in AR42J cells. Conclusions: GHRL stimulates its own expression and expression of its receptor in isolated pancreatic acinar cells and AR42J cells on the positive feedback pathway. This mechanism seems to participate in the pancreatoprotective effect of GHRL in the course of acute pancreatitis.
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Apu AS, Mondal A, Kitazawa T, Takemi S, Sakai T, Sakata I. Molecular cloning of motilin and mechanism of motilin-induced gastrointestinal motility in Japanese quail. Gen Comp Endocrinol 2016; 233:53-62. [PMID: 27179882 DOI: 10.1016/j.ygcen.2016.05.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 05/10/2016] [Accepted: 05/11/2016] [Indexed: 12/16/2022]
Abstract
Motilin, a peptide hormone produced in the upper intestinal mucosa, plays an important role in the regulation of gastrointestinal (GI) motility. In the present study, we first determined the cDNA and amino acid sequences of motilin in the Japanese quail and studied the distribution of motilin-producing cells in the gastrointestinal tract. We also examined the motilin-induced contractile properties of quail GI tracts using an in vitro organ bath, and then elucidated the mechanisms of motilin-induced contraction in the proventriculus and duodenum of the quail. Mature quail motilin was composed of 22 amino acid residues, which showed high homology with chicken (95.4%), human (72.7%), and dog (72.7%) motilin. Immunohistochemical analysis showed that motilin-immunopositive cells were present in the mucosal layer of the duodenum (23.4±4.6cells/mm(2)), jejunum (15.2±0.8cells/mm(2)), and ileum (2.5±0.7cells/mm(2)), but were not observed in the crop, proventriculus, and colon. In the organ bath study, chicken motilin induced dose-dependent contraction in the proventriculus and small intestine. On the other hand, chicken ghrelin had no effect on contraction in the GI tract. Motilin-induced contraction in the duodenum was not inhibited by atropine, hexamethonium, ritanserin, ondansetron, or tetrodotoxin. However, motilin-induced contractions in the proventriculus were significantly inhibited by atropine and tetrodotoxin. These results suggest that motilin is the major stimulant of GI contraction in quail, as it is in mammals and the site of action of motilin is different between small intestine and proventriculus.
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Affiliation(s)
- Auvijit Saha Apu
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Anupom Mondal
- Area of Life-NanoBio, Division of Strategy Research, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Takio Kitazawa
- Comparative Animal Pharmacology Department of Veterinary Science, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501, Japan
| | - Shota Takemi
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Takafumi Sakai
- Area of Life-NanoBio, Division of Strategy Research, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Ichiro Sakata
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan.
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20
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Hellström PM, Tack J, Johnson LV, Hacquoil K, Barton ME, Richards DB, Alpers DH, Sanger GJ, Dukes GE. The pharmacodynamics, safety and pharmacokinetics of single doses of the motilin agonist, camicinal, in type 1 diabetes mellitus with slow gastric emptying. Br J Pharmacol 2016; 173:1768-77. [PMID: 26924243 DOI: 10.1111/bph.13475] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 01/29/2016] [Accepted: 02/14/2016] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE Here we have investigated the pharmacokinetics, pharmacodynamics and safety of single doses of camicinal in type 1 diabetes mellitus (T1DM) patients with a history of slow gastric emptying with symptoms consistent with gastroparesis. EXPERIMENTAL APPROACH In a randomized, double-blind, placebo-controlled, incomplete block, three-period, two-centre crossover study, patients received oral administration of placebo and two of the three possible doses of camicinal (25, 50 or 125 mg). Gastric emptying ((13) C-octanoic acid breath test), pharmacokinetics and safety were primary outcomes. KEY RESULTS Nine of the 10 patients enrolled completed the study. Gastric half-emptying time decreased by -95 min (95% CI: -156.8, -34.2) after a single dose of camicinal 125 mg compared with placebo (52 vs. 147 min, P < 0.05), representing a 65% improvement. A decrease of the gastric half-emptying time compared with placebo (approximately 39 min) was observed with camicinal 25 and 50 mg, representing a 27% reduction for both doses (not statistically significant). A positive exposure-response relationship was demonstrated across all doses. The effects of camicinal on gastric half-emptying time were not influenced by fasting glucose levels. Single doses up to 125 mg were well tolerated. Camicinal was well absorbed, exhibiting linear and approximately dose-proportional pharmacokinetic characteristics and a clear exposure-response relationship with gastric emptying. CONCLUSIONS AND IMPLICATIONS Camicinal significantly accelerated gastric emptying of solids in T1DM patients following administration of a single oral dose. Camicinal was well tolerated and exhibited similar pharmacokinetic characteristics in diabetic patients to those previously reported in healthy volunteers.
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Affiliation(s)
| | | | | | | | | | | | - David H Alpers
- Washington University School of Medicine, St Louis, MO, USA
| | - Gareth J Sanger
- Barts & The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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Broad J, Takahashi N, Tajimi M, Sudo M, Góralczyk A, Parampalli U, Mannur K, Yamamoto T, Sanger GJ. RQ-00201894: A motilin receptor agonist causing long-lasting facilitation of human gastric cholinergically-mediated contractions. J Pharmacol Sci 2016; 130:60-5. [DOI: 10.1016/j.jphs.2015.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 10/05/2015] [Accepted: 11/11/2015] [Indexed: 12/11/2022] Open
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Abstract
The gastrointestinal tract is the major source of the related hormones ghrelin and motilin, which act on structurally similar G protein-coupled receptors. Nevertheless, selective receptor agonists are available. The primary roles of endogenous ghrelin and motilin in the digestive system are to increase appetite or hedonic eating (ghrelin) and initiate phase III of gastric migrating myoelectric complexes (motilin). Ghrelin and motilin also both inhibit nausea. In clinical trials, the motilin receptor agonist camicinal increased gastric emptying, but at lower doses reduced gastroparesis symptoms and improved appetite. Ghrelin receptor agonists have been trialled for the treatment of diabetic gastroparesis because of their ability to increase gastric emptying, but with mixed results; however, relamorelin, a ghrelin agonist, reduced nausea and vomiting in patients with this disorder. Treatment of postoperative ileus with a ghrelin receptor agonist proved unsuccessful. Centrally penetrant ghrelin receptor agonists stimulate defecation in animals and humans, although ghrelin itself does not seem to control colorectal function. Thus, the most promising uses of motilin receptor agonists are the treatment of gastroparesis or conditions with slow gastric emptying, and ghrelin receptor agonists hold potential for the reduction of nausea and vomiting, and the treatment of constipation. Therapeutic, gastrointestinal roles for receptor antagonists or inverse agonists have not been identified.
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23
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Broad J, Sanger GJ. The antibiotic azithromycin is a motilin receptor agonist in human stomach: comparison with erythromycin. Br J Pharmacol 2015. [PMID: 23190027 DOI: 10.1111/bph.12077] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE The antibiotic azithromycin is a suggested alternative to erythromycin for treating patients with delayed gastric emptying. However, although hypothesized to activate motilin receptors, supportive evidence is unavailable. This was investigated using recombinant and naturally expressed motilin receptors in human stomach, comparing azithromycin with erythromycin. EXPERIMENTAL APPROACH [(125)I]-motilin binding and calcium flux experiments were conducted using human recombinant motilin receptors in CHO cells. Neuromuscular activities were studied using circular muscle of human gastric antrum, after electrical field stimulation (EFS) of intrinsic nerves. KEY RESULTS Azithromycin (1-100 μM) and erythromycin (3-30 μM) concentration-dependently displaced [(125)I]-motilin binding to the motilin receptor (52 ± 7 and 58 ± 18% displacement at 100 and 30 μM respectively). Azithromycin, erythromycin and motilin concentration-dependently caused short-lived increases in intracellular [Ca(2+)] in cells expressing the motilin receptor. EC50 values were, respectively, 2.9, 0.92 and 0.036 μM (n = 3 each); and maximal activities were similar. In human stomach, EFS evoked cholinergically mediated contractions, attenuated by simultaneous nitrergic activation. Azithromycin and erythromycin lactobionate (30-300 μM each) facilitated these contractions (apparent E(max) values of 2007 ± 396 and 1924 ± 1375%, n = 3-4 each concentration, respectively). These actions were slow in onset and faded slowly. The higher concentrations also evoked short-lived muscle contraction. Contractions to a submaximally effective concentration of carbachol were unaffected by either drug. CONCLUSIONS AND IMPLICATIONS Azithromcyin activates human recombinant motilin receptors in therapeutically relevant concentrations, similar to erythromycin. In humans, gastric antrum azithromycin caused long-lasting facilitation of cholinergic activity. These actions explain the gastric prokinetic activity of azithromycin.
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Affiliation(s)
- John Broad
- Neurogastroenterology Group, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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Takahashi H, Rikimaru K, Komatsu M, Uemoto Y, Suzuki K. Association between Motilin Receptor Gene Haplotypes and Growth Traits in Japanese Hinai-dori Crossbred Chickens. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2014; 27:316-23. [PMID: 25049957 PMCID: PMC4093263 DOI: 10.5713/ajas.2013.13500] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 11/16/2013] [Accepted: 10/10/2013] [Indexed: 12/29/2022]
Abstract
We previously identified quantitative trait loci (QTL) for body weight and average daily gain in a common region between ADL0198 (chr 1: 171.7 Mb) and ABR0287 (chr 1: 173.4 Mb) on chicken chromosome 1 in an F2 resource population produced by crossing low- and high-growth lines of the Hinai-dori breed. Motilin receptor (MLNR) is a candidate gene affecting growth traits in the region. In this study, we genotyped polymorphisms of the MLNR gene and investigated its association with growth traits in a Hinai-dori F2 intercross population. All the exons of the MLNR gene in the parental population were subjected to PCR amplification, nucleotide sequenced and haplotypes identified. To distinguish resultant diplotype individuals in the F2 population, a mismatch amplification mutation assay was performed. Three haplotypes (Haplotypes 1–3) were accordingly identified. Six genotypes produced by the combination of three haplotypes (Haplotype 1, 2, and 3) were examined in order to identify associations between MLNR haplotypes and growth traits. The data showed that Haplotype 1 was superior to Haplotype 2 and 3 in body weight at 10 and 14 weeks of age, average daily gain between 4 and 10 weeks, 10 and 14 weeks, and 0 and 14 weeks of age in female in F2 females. It was concluded that MLNR is a useful marker of growth traits and could be used to develop strategies for improving growth traits in the Hinai-dori breed.
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Affiliation(s)
- Hideaki Takahashi
- Akita Prefectural Livestock Experiment Station, Daisen 019-1701, Japan
| | - Kazuhiro Rikimaru
- Akita Prefectural Livestock Experiment Station, Daisen 019-1701, Japan
| | - Megumi Komatsu
- Akita Prefectural Livestock Experiment Station, Daisen 019-1701, Japan
| | - Yoshinobu Uemoto
- National Livestock Breeding Center, Nishigo, Fukushima 961-8511, Japan
| | - Keiichi Suzuki
- Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan
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Broad J, Góralczyk A, Mannur K, Dukes GE, Sanger GJ. Drugs acting at 5-HT4 , D2 , motilin, and ghrelin receptors differ markedly in how they affect neuromuscular functions in human isolated stomach. Neurogastroenterol Motil 2014; 26:851-61. [PMID: 24750304 DOI: 10.1111/nmo.12338] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 03/10/2014] [Indexed: 02/08/2023]
Abstract
BACKGROUND Progress in identifying safer, effective drugs to increase gastric emptying is impeded by failed clinical trials. One potential reason for failure is lack of translation from animal models to the human condition. To make progress, the actions of existing drugs and new therapeutic candidates need to be understood in human isolated stomach. METHODS Neuromuscular activities were evoked in human gastric antrum circular muscle by electrical field stimulation (EFS), defined phenotypically using pharmacological tools. KEY RESULTS EFS evoked cholinergically mediated contractions, attenuated by simultaneous nitrergic activation. The 5-HT4 receptor agonist/D2 antagonist metoclopramide and the selective 5-HT4 agonist prucalopride, facilitated contractions in the absence (respectively, Emax 95 ± 29% and 42 ± 9%, n = 3-6 each concentration) and presence (139 ± 38%, 55 ± 13%, n = 3-5) of the NO synthase inhibitor L-NAME, without affecting submaximal contractions to carbachol; the 5-HT4 antagonist SB204070 prevented facilitation by metoclopramide 100 μM (respectively, -5 (range -26 to 34) and 167 (12-1327)% in presence and absence; n = 5-6). The selective motilin receptor agonist camicinal provided considerably greater facilitation (478 (12-2080)% at 30 μM, n = 8). Domperidone (0.001-100 μM; n = 3-6) and acylated or des-acylated ghrelin (1-300 nM; n = 2-4) had no consistent activity, even with protease inhibitors. CONCLUSIONS & INFERENCES 5-HT4 receptor agonists show different efficacies. Motilin receptor activation has greater potential to increase gastric emptying, whereas ghrelin and D2 receptor antagonism have no direct activity. Drugs stimulating human gastric motility directly can act regardless of disease mechanisms, whereas drugs without direct activity but an ability to block nausea/vomiting may be effective only if these symptoms exist.
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Affiliation(s)
- J Broad
- Neurogastroenterology Group, Blizard Institute, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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Sanger GJ, Broad J, Kung V, Knowles CH. Translational neuropharmacology: the use of human isolated gastrointestinal tissues. Br J Pharmacol 2014; 168:28-43. [PMID: 22946540 DOI: 10.1111/j.1476-5381.2012.02198.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 08/08/2012] [Accepted: 08/23/2012] [Indexed: 12/22/2022] Open
Abstract
Translational sciences increasingly emphasize the measurement of functions in native human tissues. However, such studies must confront variations in patient age, gender, genetic background and disease. Here, these are discussed with reference to neuromuscular and neurosecretory functions of the human gastrointestinal (GI) tract. Tissues are obtained after informed consent, in collaboration with surgeons (surgical techniques help minimize variables) and pathologists. Given the difficulties of directly recording from human myenteric neurones (embedded between muscle layers), enteric motor nerve functions are studied by measuring muscle contractions/relaxations evoked by electrical stimulation of intrinsic nerves; responses are regionally dependent, often involving cholinergic and nitrergic phenotypes. Enteric sensory functions can be studied by evoking the peristaltic reflex, involving enteric sensory and motor nerves, but this has rarely been achieved. As submucosal neurones are more accessible (after removing the mucosa), direct neuronal recordings are possible. Neurosecretory functions are studied by measuring changes in short-circuit current across the mucosa. For all experiments, basic questions must be addressed. Because tissues are from patients, what are the controls and the influence of disease? How long does it take before function fully recovers? What is the impact of age- and gender-related differences? What is the optimal sample size? Addressing these and other questions minimizes variability and raises the scientific credibility of human tissue research. Such studies also reduce animal use. Further, the many differences between animal and human GI functions also means that human tissue research must question the ethical validity of using strains of animals with unproved translational significance.
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Affiliation(s)
- G J Sanger
- Neurogastroenterology Group, Blizard Institute, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, UK.
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Sanger GJ. Ghrelin and motilin receptor agonists: time to introduce bias into drug design. Neurogastroenterol Motil 2014; 26:149-55. [PMID: 24438586 DOI: 10.1111/nmo.12300] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 12/11/2013] [Indexed: 02/08/2023]
Abstract
Ghrelin and motilin receptor agonists increase gastric motility and are attractive drug targets. However, 14 years after the receptors were described (18-24 years since ligands became available) the inactivity of the ghrelin agonist TZP-102 in patients with gastroparesis joins the list of unsuccessful motilin agonists. Fundamental questions must be asked. Pustovit et al., have now shown that the ghrelin agonist ulimorelin evokes prolonged increases in rat colorectal propulsion yet responses to other ghrelin agonists fade. Similarly, different motilin agonists induce short- or long-lasting effects in a cell-dependent manner. Together, these and other data create the hypothesis that the receptors can be induced to preferentially signal ('biased agonism') via particular pathways to evoke different responses with therapeutic advantages/disadvantages. Biased agonism has been demonstrated for ghrelin. Are motilin agonists which cause long-lasting facilitation of human stomach cholinergic function (compared with motilin) biased agonists (e.g., camicinal, under development for patients with gastric hypo-motility)? For ghrelin, additional complications exist because the therapeutic aims/mechanisms of action are uncertain, making it difficult to select the best (biased) agonist. Will ghrelin agonists be useful treatments of nausea and/or as suggested by Pustovit et al., chronic constipation? How does ghrelin increase gastric motility? As gastroparesis symptoms poorly correlate with delayed gastric emptying (yet gastro-prokinetic drugs can provide relief: e.g., low-dose erythromycin), would low doses of ghrelin and motilin agonists relieve symptoms simply by restoring neuromuscular rhythm? These questions on design and functions need addressing if ghrelin and motilin agonists are to reach patients as drugs.
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Affiliation(s)
- G J Sanger
- Neurogastroenterology Group, Blizard Institute, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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Sanger GJ, Wang Y, Hobson A, Broad J. Motilin: towards a new understanding of the gastrointestinal neuropharmacology and therapeutic use of motilin receptor agonists. Br J Pharmacol 2013; 170:1323-32. [PMID: 23189978 PMCID: PMC3838679 DOI: 10.1111/bph.12075] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 10/26/2012] [Accepted: 11/15/2012] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED The gastrointestinal hormone motilin has been known about for >40 years, but after identification of its receptor and subsequent development of new tools and methods, a reappraisal of its actions is required. Firstly, it is important to note that motilin and ghrelin receptors are members of the same family (similar genomic organization, gastrointestinal distribution and abilities to stimulate gastrointestinal motility), yet each fails to recognize the ligand of the other; and whereas ghrelin and ghrelin receptors are widespread outside the gastrointestinal tract, motilin and its receptors are largely restricted to the gastrointestinal tract. Secondly, although some studies suggest motilin has activity in rodents, most do not, and receptor pseudogenes exist in rodents. Thirdly, motilin preferentially operates by facilitating enteric cholinergic activity rather than directly contracting the muscle, despite the relatively high expression of receptor immunoreactivity in muscle. This activity is ligand-dependent, with short-lasting actions of motilin contrasting with longer-lasting actions of the non-selective and selective motilin receptor agonists erythromycin and GSK962040. Finally, the use of erythromycin (also an antibiotic drug) to treat patients requiring acceleration of gastric emptying has led to concerns over safety and potential exacerbation of antibiotic resistance. Replacement motilin receptor agonists derived from erythromycin (motilides) have been unsuccessful. New, non-motilide, small molecule receptor agonists, designed to minimize self-desensitization, are now entering clinical trials for treating patients undergoing enteral feeding or with diabetic gastroparesis. Thus, for the translational pharmacologist, the study of motilin illustrates the need to avoid overreliance on artificial systems, on structural information and on animal studies. LINKED ARTICLES This article is part of a themed section on Neuropeptides. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.170.issue-7.
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Affiliation(s)
- G J Sanger
- Neurogastroenterology Group, Blizard Institute, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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Sanger GJ, Broad J, Andrews PL. The relationship between gastric motility and nausea: Gastric prokinetic agents as treatments. Eur J Pharmacol 2013; 715:10-4. [DOI: 10.1016/j.ejphar.2013.06.031] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 06/05/2013] [Accepted: 06/21/2013] [Indexed: 12/26/2022]
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Broad J, Mukherjee S, Samadi M, Martin JE, Dukes GE, Sanger GJ. Regional- and agonist-dependent facilitation of human neurogastrointestinal functions by motilin receptor agonists. Br J Pharmacol 2013; 167:763-74. [PMID: 22537158 DOI: 10.1111/j.1476-5381.2012.02009.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND AND PURPOSE Delayed gastric emptying is poorly managed. Motilin agonists are potential treatments but inadequate understanding into how enteric nerve functions are stimulated compromises drug/dose selection. Resolution is hampered by extreme species dependency so methods were developed to study human gastrointestinal neuromuscular activities and the neurobiology of motilin. EXPERIMENTAL APPROACH Protocols to study neuromuscular activities were developed for different regions of human stomach and intestine (71 patients) using circular muscle preparations and electrical field stimulation (EFS) of intrinsic nerves. Other tissues were fixed for immunohistochemistry. KEY RESULTS EFS evoked contractions and/or relaxations via cholinergic and nitrergic neurons, with additional tachykinergic activity in colon; these were consistent after 154 min (longer if stored overnight). Motilin 1-300 nM and the selective motilin agonist GSK962040 0.1-30 µM acted pre-junctionally to strongly facilitate cholinergic contractions of the antrum (E(max) ≈ 1000% for motilin), with smaller increases in fundus, duodenum and ileum; high concentrations increased baseline muscle tension in fundus and small intestine. There were minimal effects in the colon. In the antrum, cholinergic facilitation by motilin faded irregularly, even with peptidase inhibitors, whereas facilitation by GSK962040 was long lasting. Motilin receptor immunoreactivity was identified in muscle and myenteric plexus predominantly in the upper gut, co-expressed with choline acetyltransferase in neurons. CONCLUSIONS AND IMPLICATIONS Motilin and GSK962040 strongly facilitated cholinergic activity in the antrum, with lower activity in fundus and small intestine only. Facilitation by motilin was short lived, consistent with participation in migrating motor complexes. Long-lasting facilitation by GSK962040 suggests different receptor interactions and potential for clinical evaluation.
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Affiliation(s)
- J Broad
- Neurogastroenterology group, Blizard Institute, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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Depoortere I. Can small non-peptide motilin agonists force a breakthrough as gastroprokinetic drugs? Br J Pharmacol 2013; 167:760-2. [PMID: 22616752 DOI: 10.1111/j.1476-5381.2012.02046.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
GSK962040 is a small selective motilin receptor agonist currently under investigation in clinical trials for the treatment of conditions associated with delayed gastric emptying. As reported in this issue of the British Journal of Pharmacology, Broad et al., studied for the first time the region-dependent contractile effects of motilin and GSK962040 in human smooth muscle strips. Both compounds facilitated cholinergically mediated contractions of human gastric antral muscle strips at low concentrations and induced smooth muscle contractions at high concentrations. The effect was less pronounced in the fundus and almost absent in the colon. The long-lasting facilitation of cholinergic responses in the antrum by GSK962040 compared with the fading responses to motilin may be of importance from a clinical point of view. The approach used by Broad et al. with human tissue is a validated model to identify motilin receptor agonists with therapeutic value.
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Affiliation(s)
- Inge Depoortere
- Translational Research Center for Gastrointestinal Disorders, Catholic University of Leuven, Herestraat 49, Leuven, Belgium.
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Javid FA, Bulmer DC, Broad J, Aziz Q, Dukes GE, Sanger GJ. Anti-emetic and emetic effects of erythromycin in Suncus murinus: role of vagal nerve activation, gastric motility stimulation and motilin receptors. Eur J Pharmacol 2012. [PMID: 23201066 DOI: 10.1016/j.ejphar.2012.11.035] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Paradoxically, erythromycin is associated with nausea when used as an antibiotic but at lower doses erythromycin activates motilin receptors and is used to treat delayed gastric emptying and nausea. The aim of this study was to characterise pro- and anti-emetic activity of erythromycin and investigate mechanisms of action. Japanese House musk shrews (Suncus murinus) were used. Erythromycin was administered alone or prior to induction of emesis with abnormal motion or subcutaneous nicotine (10mg/kg). The effects of erythromycin and motilin on vagal nerve activity and on cholinergically mediated contractions of the stomach (evoked by electrical field stimulation) were studied in vitro. The results showed that erythromycin (1 and 5mg/kg) reduced vomiting caused by abnormal motion (e.g., from 10.3 ± 1.8 to 4.0 ± 1.1 emetic episodes at 5mg/kg) or by nicotine (from 9.5 ± 2.0 to 3.1 ± 2.0 at 5mg/kg), increasing latency of onset to emesis; lower or higher doses had no effects. When administered alone, erythromycin 100mg/kg induced vomiting in two of four animals, whereas lower doses did not. In vitro, motilin (1, 100 nM) increased gastric vagal afferent activity without affecting jejunal afferent mesenteric nerve activity. Cholinergically mediated contractions of the stomach (prevented by tetrodotoxin 1 μM or atropine 1 μM, facilitated by l-NAME 300 μM) were facilitated by motilin (1-100 nM) and erythromycin (10-30 μM). In conclusion, low doses of erythromycin have anti-emetic activity. Potential mechanisms of action include increased gastric motility (overcoming gastric stasis) and/ or modulation of vagal nerve pathways involved in emesis, demonstrated by first-time direct recording of vagal activation by motilin.
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Affiliation(s)
- Farideh A Javid
- School of Applied Sciences, Division of Pharmacy and Pharmaceuticals Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK
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He J, Zhou T, Irwin DM, Shen Y, Zhang Y. The Motilin Gene Evolved a New Function in Kangaroo Rats and Kangaroo Mice (Dipodomyinae). J Mol Evol 2012; 75:112-8. [DOI: 10.1007/s00239-012-9522-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 09/24/2012] [Indexed: 12/20/2022]
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Sanger GJ. Motilin receptor neuropharmacology: revised understanding. Curr Opin Pharmacol 2012; 12:641-6. [PMID: 22858405 DOI: 10.1016/j.coph.2012.07.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/12/2012] [Accepted: 07/17/2012] [Indexed: 12/17/2022]
Abstract
Although motilin was identified >40 years ago as a gastrointestinal hormone capable of stimulating gastric emptying, the relatively recent availability of molecular tools and focus on its neuronal activities are now clarifying mechanisms of action. In rodents, only motilin receptor pseudogenes are identified. In human stomach, facilitation of enteric cholinergic activity is identified as the main mechanism by which gastric emptying is increased; some motilin agonists act in a prolonged manner, contrasting with motilin itself and with studies using recombinant receptors. As such, assays using recombinant receptors seem poor predictors of in vivo activity. High-throughput screening enabled selective motilin agonists to be identified, which together with enhanced understanding into neuromuscular actions of motilin, promises to deliver rational treatments of disorders with delayed gastric emptying.
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Affiliation(s)
- Gareth J Sanger
- Neurogastroenterology Group, Blizard Institute, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom.
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Nunoi H, Matsuura B, Utsunomiya S, Ueda T, Miyake T, Furukawa S, Kumagi T, Ikeda Y, Abe M, Hiasa Y, Onji M. A relationship between motilin and growth hormone secretagogue receptors. ACTA ACUST UNITED AC 2012; 176:28-35. [DOI: 10.1016/j.regpep.2012.03.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 02/27/2012] [Accepted: 03/20/2012] [Indexed: 12/19/2022]
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Miegueu P, Cianflone K, Richard D, St-Pierre DH. Motilin stimulates preadipocyte proliferation and differentiation and adipocyte lipid storage. Am J Physiol Endocrinol Metab 2011; 301:E758-66. [PMID: 21771971 DOI: 10.1152/ajpendo.00089.2011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Motilin is a circulating gastrointestinal peptide secreted primarily by duodenal mucosal M cells and recognized for its prokinetic effects on gastrointestinal tissues. Little information is available regarding effects on insulin/glucose homeostasis or adipocyte function. Our aim was to evaluate the effects of motilin on adipocyte proliferation, differentiation, lipolysis, and macronutrient uptake in adipocytes. 3T3-L1 cells and primary rat adipocytes were treated acutely and chronically with varying motilin concentrations, and effects were compared with vehicle alone (control), set as 100% for all assays. In preadipocytes, motilin stimulated proliferation ([(3)H]thymidine incorporation) and mitochondrial activity (141 ± 10%, P < 0.001 and 158 ± 10%, respectively, P < 0.001), in a concentration-dependent manner. Chronic supplementation with motilin during differentiation further increased lipogenesis (Oil red O staining 191 ± 27%, P < 0.05) and was associated with an upregulation of PPARγ (148 ± 8%, P < 0.01), C/EBPα (142 ± 17%, P < 0.05), and Cav3 (166 ± 20%, P < 0.05) expression. In mature 3T3-L1 adipocytes motilin increased fatty acid uptake/incorporation (≤ 202 ± 12%; P < 0.01) and glucose uptake (146 ± 9% P < 0.05) and decreased net fatty acid release (maximal -31%, P < 0.05) without influencing total lipolysis (glycerol release). Similar effects were obtained in primary rat adipocytes. Motilin acutely increased expression of PPARγ, CEBPβ, DGAT1, and CD36 while decreasing adiponectin mRNA and secretion. In human adipose tissue, motilin receptor GPR38 correlated with HOMA-IR and GHSR1 (r = 0.876, P < 0.0001). Motilin binding and fatty acid incorporation into adipocytes were inhibited by antagonists MB10 and [D-lys3]-GRP6 and PI 3-kinase inhibitor wortmannin. Taken together, these results suggest that motilin may directly influence adipocyte functions by stimulating energy storage.
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Affiliation(s)
- Pierre Miegueu
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec, Canada
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Leming S, Broad J, Cozens SJ, Otterson M, Winchester W, Lee K, Dukes GE, Sanger GJ. GSK962040: a small molecule motilin receptor agonist which increases gastrointestinal motility in conscious dogs. Neurogastroenterol Motil 2011; 23:958-e410. [PMID: 21895874 DOI: 10.1111/j.1365-2982.2011.01770.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND GSK962040, a small molecule motilin receptor agonist, was identified to address the need for a safe, efficacious gastric prokinetic agent. However, as laboratory rodents lack a functional motilin system, studies in vivo have been limited to a single dose, which increased defecation in rabbits. Motilin agonists do not usually increase human colonic motility, so gastric prokinetic activity needs to be demonstrated. METHODS The effect of intravenous GSK962040 on gastro-duodenal motility was assessed in fasted dogs implanted with strain gauges. Activity was correlated with blood plasma concentrations of GSK962040 (measured by HPLC-MS/MS) and potency of GSK962040 at the dog recombinant receptor [using a Fluorometric Imaging Plate Reader (Molecular Devices, Wokingham, UK) after expression in HEK293 cells]. KEY RESULTS GSK962040 activated the dog motilin receptor (pEC(50) 5.79; intrinsic activity 0.72, compared with [Nle(13) ]-motilin). In vivo, GSK962040 induced phasic contractions, the duration of which was dose-related (48 and 173 min for 3 and 6 mg kg(-1) ), driven by mean plasma concentrations >1.14 μmol L(-1) . After the effects of GSK962040 faded, migrating motor complex (MMC) activity returned. Migrating motor complex restoration was unaffected by 3 mg kg(-1) GSK962040 but at 6 mg kg(-1) , MMCs returned 253 min after dosing, compared with 101 min after saline (n=5 each). CONCLUSIONS & INFERENCES The results are consistent with lower potency for agonists at the dog motilin receptor, compared with humans. They also define the doses of GSK962040 which stimulate gastric motility. Correlation of in vivo and in vitro data in the same species, together with plasma concentrations, guides further studies and translation to other species.
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Affiliation(s)
- S Leming
- Zablocki VAMC, Wisconsin Corporation for Biomedical Research, Milwaukee, WI, USA
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Miegueu P, St Pierre D, Broglio F, Cianflone K. Effect of desacyl ghrelin, obestatin and related peptides on triglyceride storage, metabolism and GHSR signaling in 3T3-L1 adipocytes. J Cell Biochem 2011; 112:704-14. [PMID: 21268092 DOI: 10.1002/jcb.22983] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Acyl-ghrelin (AG), desacyl-ghrelin (DAG) and obestatin are all derived from the same gene transcript; however their plasma levels do not necessarily change in parallel. The influence of these peptides towards the development of obesity and their direct effects on adipocyte physiology has not been thoroughly investigated. This study was designed to evaluate the direct effects of peptides of the ghrelin family on preadipocyte proliferation, differentiation and adipocyte lipid and glucose metabolism in 3T3-L1 cells. 3T3 cells were treated with physiological peptide concentrations for 1 h to 9 days, and the relevant assays measured. In preadipocytes, AG, GHRP-6 and DAG stimulated proliferation, measured as (3)H-thymidine incorporation (up to 200%, P < 0.05), while all peptides stimulated differentiation (up to 300%, P < 0.01) as compared to standard differentiation conditions. In adipocytes, FA uptake was increased in a concentration-dependent manner especially with obestatin (three- to fourfold, P < 0.001) and DAG (three- to fivefold, P < 0.001). By contrast, glucose transport was unchanged. DAG and obestatin significantly decreased lipolysis measured as non-esterified fatty acid and glycerol release by 50%, P < 0.05-0.01 and 51%, P < 0.01, respectively. Interestingly, DAG stimulation of FA uptake was blocked with GHSR1 antagonist (D-lys(3))-GHRP-6 (P < 0.05), phospholipase C inhibitor U73122 and phosphatidylinositol-3-kinase inhibitor wortmannin (P < 0.001). Finally, in omental but not subcutaneous human adipose tissue, GHSR1 correlated with BMI (r = 0.549, P < 0.05) and insulin (r = 0.681, P < 0.01). Taken together, these results suggest that ghrelin-related peptides may directly affect adipose tissue metabolism.
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Affiliation(s)
- Pierre Miegueu
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec, QC, Canada
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Sanger GJ, Holbrook JD, Andrews PLR. The translational value of rodent gastrointestinal functions: a cautionary tale. Trends Pharmacol Sci 2011; 32:402-9. [PMID: 21531468 DOI: 10.1016/j.tips.2011.03.009] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Revised: 03/18/2011] [Accepted: 03/22/2011] [Indexed: 02/06/2023]
Abstract
Understanding relationships between gene complements and physiology is important, especially where major species-dependent differences are apparent. Molecular and functional differences between rodents (rats, mice, guinea pigs) and humans are increasingly reported. Recently, the motilin gene, which encodes a gastrointestinal hormone widely detected in mammals, was found to be absent in rodents where the receptors are pseudogenes; however, actions of motilin in rodents are sometimes observed. Although ghrelin shares common ancestry with motilin, major species-dependent abberations are not reported. The apparently specific absence of functional motilin in rodents is associated with specialised digestive physiology, including loss of ability to vomit; motilin is functional in mammals capable of vomiting. The exception is rabbit, the only other mammal unable to vomit, in which motilin might be conserved to regulate caecotrophy, another specialised digestive process. Motilin illustrates a need for caution when translating animal functions to humans. Nevertheless, motilin receptor agonists are under development as gastroprokinetic drugs.
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Affiliation(s)
- Gareth J Sanger
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, 26 Ashfield Street, London, E1 2AJ, UK.
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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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Popovics P, Stewart AJ. GPR39: a Zn(2+)-activated G protein-coupled receptor that regulates pancreatic, gastrointestinal and neuronal functions. Cell Mol Life Sci 2011; 68:85-95. [PMID: 20812023 PMCID: PMC11114682 DOI: 10.1007/s00018-010-0517-1] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 08/16/2010] [Accepted: 08/17/2010] [Indexed: 10/19/2022]
Abstract
GPR39 is a vertebrate G protein-coupled receptor related to the ghrelin/neurotensin receptor subfamily. The receptor is expressed in a range of tissues including the pancreas, gut/gastrointestinal tract, liver, kidney and in some regions of the brain. GPR39 was initially thought to be the cognitive receptor for the peptide hormone, obestatin. However, subsequent in vitro studies have failed to demonstrate binding of this peptide to the receptor. Zn(2+) has been shown to be a potent stimulator of GPR39 activity via the Gα(q), Gα(12/13) and Gα(s) pathways. The potency and specificity of Zn(2+) in activating GPR39 suggest it to be a physiologically important agonist. GPR39 is now emerging as an important transducer of autocrine and paracrine Zn(2+) signals, impacting upon cellular processes such as insulin secretion, gastric emptying, neurotransmission and epithelial repair. This review focuses on the molecular, structural and biological properties of GPR39 and its various physiological functions.
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Affiliation(s)
- Petra Popovics
- School of Medicine, University of St Andrews, Medical and Biological Sciences Building, St Andrews, Fife KY16 9TF UK
| | - Alan J. Stewart
- School of Medicine, University of St Andrews, Medical and Biological Sciences Building, St Andrews, Fife KY16 9TF UK
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De Smet B, Mitselos A, Depoortere I. Motilin and ghrelin as prokinetic drug targets. Pharmacol Ther 2009; 123:207-23. [DOI: 10.1016/j.pharmthera.2009.04.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 04/09/2009] [Indexed: 12/13/2022]
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sanger GJ, westaway SM, barnes AA, macpherson DT, muir AI, jarvie EM, bolton VN, cellek S, näslund E, hellström PM, borman RA, unsworth WP, matthews KL, lee K. GSK962040: a small molecule, selective motilin receptor agonist, effective as a stimulant of human and rabbit gastrointestinal motility. Neurogastroenterol Motil 2009. [DOI: 10.1111/j.1365-2982.2009.01270.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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Venkova K, Thomas H, Fraser GL, Meerveld BGV. Effect of TZP-201, a novel motilin receptor antagonist, in the colon of the musk shrew ( Suncus murinus). J Pharm Pharmacol 2009. [DOI: 10.1211/jpp.61.03.0012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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45
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Westaway SM, Sanger GJ. The identification of and rationale for drugs which act at the motilin receptor. PROGRESS IN MEDICINAL CHEMISTRY 2009; 48:31-80. [PMID: 21544957 DOI: 10.1016/s0079-6468(09)04802-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Affiliation(s)
- Susan M Westaway
- Immuno-Inflammation CEDD, GlaxoSmithKline, Medicines Research Centre, Gunnels Wood Road, Stevenage, Herts SG1 2NY, UK
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Westaway SM, Brown SL, Conway E, Heightman TD, Johnson CN, Lapsley K, Macdonald GJ, MacPherson DT, Mitchell DJ, Myatt JW, Seal JT, Stanway SJ, Stemp G, Thompson M, Celestini P, Colombo A, Consonni A, Gagliardi S, Riccaboni M, Ronzoni S, Briggs MA, Matthews KL, Stevens AJ, Bolton VJ, Boyfield I, Jarvie EM, Stratton SC, Sanger GJ. The discovery of biaryl carboxamides as novel small molecule agonists of the motilin receptor. Bioorg Med Chem Lett 2008; 18:6429-36. [DOI: 10.1016/j.bmcl.2008.10.072] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 10/15/2008] [Accepted: 10/16/2008] [Indexed: 11/26/2022]
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47
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Heightman TD, Conway E, Corbett DF, Macdonald GJ, Stemp G, Westaway SM, Celestini P, Gagliardi S, Riccaboni M, Ronzoni S, Vaidya K, Butler S, McKay F, Muir A, Powney B, Winborn K, Wise A, Jarvie EM, Sanger GJ. Identification of small molecule agonists of the motilin receptor. Bioorg Med Chem Lett 2008; 18:6423-8. [PMID: 18980843 DOI: 10.1016/j.bmcl.2008.10.071] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 10/15/2008] [Accepted: 10/16/2008] [Indexed: 11/19/2022]
Abstract
High-throughput screening resulted in the identification of a series of novel motilin receptor agonists with relatively low molecular weights. The series originated from an array of biphenyl derivatives designed to target 7-transmembrane (7-TM) receptors. Further investigation of the structure-activity relationship within the series resulted in the identification of compound (22) as a potent and selective agonist at the motilin receptor.
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Affiliation(s)
- Tom D Heightman
- Neurology & GI Centre of Excellence for Drug Discovery, GlaxoSmithKline, New Frontiers Science Park, Third Avenue, Harlow, Essex CM19 5AW, UK.
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Abstract
The endogenous ligand for growth-hormone secretagogue receptor (GHS-R) was purified from the stomach and we named it "ghrelin", after a word root ("ghre") in Proto-Indo-European languages meaning "grow", since ghrelin has potent growth hormone (GH) releasing activity. In addition, ghrelin stimulates appetite by acting on the hypothalamic arcuate nucleus, a region known to control food intake. Ghrelin is orexigenic; it is secreted from the stomach and circulates in the blood stream under fasting conditions, indicating that it transmits a hunger signal from the periphery to the central nervous system. Taking into account all these activities, ghrelin plays important roles for maintaining growth hormone release and energy homeostasis in vertebrates. The diverse functions of ghrelin raise the possibility of its clinical application for GH deficiency, eating disorder, gastrointestinal disease, cardiovascular disease, osteoporosis and aging, etc.
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Yamamoto I, Kaiya H, Tsutsui C, Sakai T, Tsukada A, Miyazato M, Tanaka M. Primary structure, tissue distribution, and biological activity of chicken motilin receptor. Gen Comp Endocrinol 2008; 156:509-14. [PMID: 18433751 DOI: 10.1016/j.ygcen.2008.03.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 03/10/2008] [Accepted: 03/11/2008] [Indexed: 10/22/2022]
Abstract
Motilin is a peptide hormone involved in gastrointestinal motility. GPR38, initially cloned as an orphan receptor, is now considered a specific receptor for motilin. Previously, molecular characterization of the motilin receptor had only been performed in mammalian and fish species. In this study, we cloned cDNA for chicken motilin receptor from the duodenum and characterized its primary structure, tissue distribution, and biological activity. The cDNA encoded 349 amino acids showing significant overall sequence identity to mammalian motilin receptors. Chicken motilin increased intracellular Ca2+ concentration in human embryonic kidney (HEK) 293 cells transiently expressing the recombinant chicken motilin receptor. Comparison of the cDNA sequence with the genomic sequence of chicken motilin receptor revealed that the chicken motilin receptor gene consists of two exons separated by an intron. Real-time PCR analysis showed that chicken motilin receptor mRNA is expressed in a wide range of tissues in 21-day-old chickens, with markedly high levels in the proventriculus, duodenum, and oviduct. The expression levels of the mRNA in the proventriculus and duodenum were highest just before hatching and rapidly decreased during post-hatch development. These results suggest that chicken motilin receptor is largely involved in gastrointestinal functions at pre- and post-hatch periods through an intracellular signaling pathway accompanied by an increase in Ca2+ levels.
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Affiliation(s)
- Ichiro Yamamoto
- High-Tech Research Center, Nippon Veterinary and Life Science University, Musashino, Tokyo 180-8602, Japan
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50
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Sanger GJ, Lee K. Hormones of the gut-brain axis as targets for the treatment of upper gastrointestinal disorders. Nat Rev Drug Discov 2008; 7:241-54. [PMID: 18309313 DOI: 10.1038/nrd2444] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The concept of the gut forming the centre of an integrated gut-brain-energy axis - modulating appetite, metabolism and digestion - opens up new paradigms for drugs that can tackle multiple symptoms in complex upper gastrointestinal disorders. These include eating disorders, nausea and vomiting, gastroesophageal reflux disease, gastroparesis, dyspepsia and irritable bowel syndrome. The hormones that modulate gastric motility represent targets for gastric prokinetic drugs, and peptides that modify eating behaviours may be targeted to develop drugs that reduce nausea, a currently poorly treated condition. The gut-brain axis may therefore provide a range of therapeutic opportunities that deliver a more holistic treatment of upper gastrointestinal disorders.
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Affiliation(s)
- Gareth J Sanger
- Immuno Inflammation Centre of Excellence for Drug Discovery, GlaxoSmithKline, Stevenage, Hertfordshire SG1 2NY, UK.
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