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Sanger GJ. Why is motilin active in some studies with mice, rats, and guinea pigs, but not in others? Implications for functional variability among rodents. Pharmacol Res Perspect 2022; 10:e00900. [PMID: 35191209 PMCID: PMC8860775 DOI: 10.1002/prp2.900] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 11/19/2021] [Indexed: 11/17/2022] Open
Abstract
The gastrointestinal (GI) hormone motilin helps control human stomach movements during hunger and promotes hunger. Although widely present among mammals, it is generally accepted that in rodents the genes for motilin and/or its receptor have undergone pseudonymization, so exogenous motilin cannot function. However, several publications describe functions of low concentrations of motilin, usually within the GI tract and CNS of mice, rats, and guinea pigs. These animals were from institute-held stocks, simply described with stock names (e.g., "Sprague-Dawley") or were inbred strains. It is speculated that variation in source/type of animal introduces genetic variations to promote motilin-sensitive pathways. Perhaps, in some populations, motilin receptors exist, or a different functionally-active receptor has a good affinity for motilin (indicating evolutionary pressures to retain motilin functions). The ghrelin receptor has the closest sequence homology, yet in non-rodents the receptors have a poor affinity for each other's cognate ligand. In rodents, ghrelin may substitute for certain GI functions of motilin, but no good evidence suggests rodent ghrelin receptors are highly responsive to motilin. It remains unknown if motilin has functional relationships with additional bioactive molecules formed from the ghrelin and motilin genes, or if a 5-TM motilin receptor has influence in rodents (e.g., to dimerize with GPCRs and create different pharmacological profiles). Is the absence/presence of responses to motilin in rodents' characteristic for systems undergoing gene pseudonymization? What are the consequences of rodent supplier-dependent variations in motilin sensitivity (or other ligands for receptors undergoing pseudonymization) on gross physiological functions? These are important questions for understanding animal variation.
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Affiliation(s)
- Gareth J. Sanger
- Blizard Institute and the National Centre for Bowel ResearchBarts and The London School of Medicine and DentistryQueen Mary University of LondonLondonUnited Kingdom
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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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Dougnon G, Ito M. Role of Ascaridole and p-Cymene in the Sleep-Promoting Effects of Dysphania ambrosioides Essential Oil via the GABAergic System in a ddY Mouse Inhalation Model. JOURNAL OF NATURAL PRODUCTS 2021; 84:91-100. [PMID: 33325703 DOI: 10.1021/acs.jnatprod.0c01137] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The essential oil obtained from Dysphania ambrosioides leaves (DAEO) has antifungal, antioxidant, and antimicrobial properties. This study investigated DAEO's chemical composition and its sleep-promoting effects via administration by inhalation in ddY mice. Ascaridole (35.5%) and p-cymene (47.2%) were the major components. To obtain insight into DAEO's effects on the central nervous system (CNS), ascaridole and p-cymene were evaluated for sedative activity by using the caffeine-treated excitatory mouse model. DAEO administration significantly decreased locomotor activity at all doses except 0.000 04 mg per 400 μL of triethyl citrate. Both ascaridole and p-cymene were highly effective in decreasing locomotor activity of excited mice by more than 50%. In addition, ascaridole and p-cymene prolonged the pentobarbital-induced sleeping duration by 42% and 77%, respectively. These effects were antagonized by coadministration of gamma-aminobutyric acid (GABAA)-benzodiazepine receptor antagonist, flumazenil (3 mg/kg), indicating that the GABAergic system mediates the sedative effect. Finally, inhaled ascaridole and p-cymene had no negative effect on motor coordination, as observed during the Rota-rod test. Therefore, via activation of the GABAergic system, ascaridole and p-cymene mediate the sleep-promoting effect of DAEO. The results further extend the knowledge on their use as potential promising natural products for the management of sleep disorders and CNS-related ailments.
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Affiliation(s)
- Godfried Dougnon
- Department of Pharmacognosy, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Michiho Ito
- Department of Pharmacognosy, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
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Anxiolytic actions of motilin in the basolateral amygdala. Mol Neurobiol 2013; 47:892-902. [PMID: 23307330 DOI: 10.1007/s12035-012-8383-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 12/04/2012] [Indexed: 10/27/2022]
Abstract
Motilin is a 22-amino-acid gastrointestinal polypeptide that was first isolated from the porcine intestine. We identified that motilin receptor is highly expressed in GABAergic interneurons in the basolateral nucleus (BLA) of the amygdala, the structure of which is closely involved in assigning stress disorder and anxiety. However, little is known about the role of motilin in BLA neuronal circuits and the molecular mechanisms of stress-related anxiety. Whole-cell recordings from amygdala slices showed that motilin depolarized the interneurons and facilitated GABAergic transmission in the BLA, which is mimicked by the motilin receptor agonist, erythromycin. BLA local injection of erythromycin or motilin can reduce the anxiety-like behavior in mice after acute stress. Therefore, motilin is essential in regulating interneuron excitability and GABAergic transmission in BLA. Moreover, the anxiolytic actions of motilin can partly be explained by modulating the BLA neuronal circuits. The present data demonstrate the importance of motilin in anxiety and the development of motilin receptor non-peptide agonist as a clear target for the potential treatment of anxiety disorders.
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U-shaped relation between plasma oxytocin levels and behavior in the trust game. PLoS One 2012; 7:e51095. [PMID: 23227239 PMCID: PMC3515439 DOI: 10.1371/journal.pone.0051095] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 10/29/2012] [Indexed: 11/19/2022] Open
Abstract
Trust underpins much of social and economic exchanges across human societies. In experimental economics, the Trust Game has served as the workhorse for the study of trust in a controlled incentivized setting. Recent evidence using intranasal drug administration, aka ‘sniffing’, suggests that oxytocin (OT) can function as a social hormone facilitating trust and other affiliative behaviors. Here we hypothesized that baseline plasma OT is a biomarker that partially predicts the degree of trust and trustworthiness observed in the trust game. Using a large sample of 1,158 participants, we observed a significant U-shaped relationship between plasma OT with the level of trust, and marginally with the level of trustworthiness, especially among males. Specifically, subjects with more extreme levels of plasma OT were more likely to be trusting as well as trustworthy than those with moderate levels of plasma OT. Our results contribute to a deeper understanding of the biological basis of human trust and underscore the usefulness of peripheral plasma OT measures in characterizing human social behavior.
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Miyamoto C, Yoshida M, Yoshikawa M, Mizushige T, Ohinata K. Complement C5a exhibits anxiolytic-like activity via the prostaglandin D2−DP1 receptor system coupled to adenosine A2A and GABAA receptors. Prostaglandins Other Lipid Mediat 2012; 98:17-22. [DOI: 10.1016/j.prostaglandins.2012.03.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 03/27/2012] [Accepted: 03/30/2012] [Indexed: 10/28/2022]
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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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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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Zhao H, Ohinata K, Yoshikawa M. Central prostaglandin D(2) exhibits anxiolytic-like activity via the DP(1) receptor in mice. Prostaglandins Other Lipid Mediat 2008; 88:68-72. [PMID: 19007903 DOI: 10.1016/j.prostaglandins.2008.10.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Accepted: 10/10/2008] [Indexed: 11/18/2022]
Abstract
We found that prostaglandin (PG) D(2), the most abundant PG produced in the central nervous system (CNS), exhibited anxiolytic-like activity at a dose of 10-100pmol/mouse after intracerebroventricular (i.c.v.) administration in the elevated plus-maze test in mice. A DP(1) receptor-selective agonist, BW245C, mimicked the anxiolytic-like activity of PGD(2), while a DP(2) receptor agonist 13,14-dihydro-15-keto-PGD(2) was inactive. The anxiolytic-like activity of PGD(2) was blocked by a DP(1) antagonist, BWA868C, suggesting that PGD(2)-induced anxiolytic-like activity was mediated by the DP(1) receptor. Adenosine A(2A) or GABA(A) receptor antagonists, SCH58261 or bicuculline, respectively, also blocked its anxiolytic-like activity. Taken together, centrally administered PGD(2) may induce anxiolytic-like activity via the A(2A) and GABA(A) receptors, downstream of the DP(1) receptor.
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Affiliation(s)
- Hui Zhao
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 611-0011, Japan
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Calabrese EJ. An Assessment of Anxiolytic Drug Screening Tests: Hormetic Dose Responses Predominate. Crit Rev Toxicol 2008; 38:489-542. [DOI: 10.1080/10408440802014238] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Abstract
Biology is replete with examples of hormesis, the term introduced and developed by Calabrese. The corresponding concept in the field of peptide research has been characterized as the inverted U-shaped dose-response relationship. The articles by Calabrese in this issue summarize the notable progress occurring in the past three decades. In contrast to the skepticism encountered when we introduced this concept for peptides in the early 1970s, hormesis is now becoming recognized as characteristic of many actions of these small proteins. Calabrese is performing a considerable service by his strong advocacy and promotion of the concept to a more general readership. Hopefully, hormesis will be routinely considered in the design of research projects and the discovery of pharmaceutical agents.
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Affiliation(s)
- Abba J Kastin
- Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, USA.
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Zhao H, Ohinata K, Yoshikawa M. Rubimetide (Met-Arg-Trp) derived from Rubisco exhibits anxiolytic-like activity via the DP1 receptor in male ddY mice. Peptides 2008; 29:629-32. [PMID: 18243414 DOI: 10.1016/j.peptides.2007.12.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 12/11/2007] [Accepted: 12/14/2007] [Indexed: 11/24/2022]
Abstract
In this study, we found that Met-Arg-Trp (rubimetide), which had been isolated as a hypotensive peptide from a pepsin-pancreatin digest of spinach ribulose bisphosphate carboxylase/oxygenase (Rubisco), has anxiolytic-like activity in the elevated plus-maze test at a dose of 0.1mg/kg (i.p.) or 1.0mg/kg (p.o.) in mice with p<0.01 and p<0.05, respectively. The anxiolytic-like activity of rubimetide (0.1mg/kg, i.p.) was blocked by BW A868C (60microg/kg, i.p.), an antagonist for the DP1 receptor, suggesting the anxiolytic-like activity of rubimetide is mediated by prostaglandin D2 and the DP1 receptor.
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Affiliation(s)
- Hui Zhao
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
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Hirata H, Sonoda S, Agui S, Yoshida M, Ohinata K, Yoshikawa M. Rubiscolin-6, a delta opioid peptide derived from spinach Rubisco, has anxiolytic effect via activating sigma1 and dopamine D1 receptors. Peptides 2007; 28:1998-2003. [PMID: 17766012 DOI: 10.1016/j.peptides.2007.07.024] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2007] [Revised: 07/21/2007] [Accepted: 07/23/2007] [Indexed: 10/23/2022]
Abstract
Rubiscolin-6 (Tyr-Pro-Leu-Asp-Leu-Phe) is a delta opioid peptide derived from the large subunit of spinach d-ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). We previously reported that rubiscolin-6 had an analgesic effect and stimulated memory consolidation. Here we show that intraperitoneally (i.p.) or orally administered rubiscolin-6 has an anxiolytic effect at a dose of 10 mg/kg or 100 mg/kg, respectively, in the elevated plus-maze test in mice. The anxiolytic effects of rubscolin-6 after i.p. (10 mg/kg) and oral (100 mg/kg) administration were blocked by a delta opioid receptor antagonist, naltrindole (1 mg/kg, s.c.), suggesting that the anxiolytic activity of rubiscolin-6 is mediated by delta opioid receptor. The anxiolytic effect of rubiscolin-6 (10 mg/kg, i.p.) was also blocked by a dopamine D(1) antagonist, SCH23390 (30 microg/kg, i.p.), but not by a dopamine D(2) antagonist, raclopride (15 microg/kg, i.p.). The anxiolytic effect of rubiscolin-6 (10 mg/kg, i.p.) was blocked by sigma(1) receptor antagonist, BMY14802 (0.5 mg/kg, i.p.) or BD1047 (10 mg/kg, i.p.). Taken together, the anxiolytic effect of rubiscolin-6 is mediated by sigma(1) and dopamine D(1) receptors downstream of delta opioid receptor.
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Affiliation(s)
- Hajime Hirata
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan
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Jia YD, Liu CQ, Tang M, Jiang ZY. Expression of motilin in the hypothalamus and the effect of central erythromycin on gastric motility in diabetic rats. Neurosci Bull 2007; 23:75-82. [PMID: 17592529 PMCID: PMC5550590 DOI: 10.1007/s12264-007-0011-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE To investigate the expression of motilin-immunoreactive neurons in the hypothalamus and the effect of central administration of erythromycin (EM) on the regulation of gastric motility in diabetic rats. METHODS The motilin immunoreactive neurons in the hypothalamus and the hippocampus were detected by immunohistochemistry with rabbit anti-motilin polyclonal antibody. To measure the gastric motility, force transducers were surgically affixed to the gastric serosa. A microinjection syringe was connected via a plastic tube to an injection cannula, which was connected with a stainless steel guide cannula. The syringe was inserted into the right lateral cerebral ventricle for microinjecting the chemicals. RESULTS Diabetic mellitus was successfully induced in cohorts of rats. Motilin-immunoreactive neurons significantly increased in the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus in the diabetic rats. Intracerebroventricular (i.c.v.) administration of EM, a motilin receptor agonist, stimulated the gastric motility of diabetic rats. EM (91.56 nmol, i.c.v.) dose-dependently increased the amplitude by (174.82 +/- 48.62)% (P<0.05), and increased the frequency by (70.43 +/- 27.11)% (P < 0.05) in 5 min. The stimulatory effect lasted more than 15 min to the end of the measurement, and can be blocked partially by the prior treatment of motilin receptor antagonist GM-109. CONCLUSION Motilin-immunoreactive neurons are increased in the PVN and SON of the hypothalamus in diabetic rats. Centrally administered EM may regulate gastric motility by binding to the central motilin receptors, and central motilin might be involved in regulation of gastric motility in diabetic rats.
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Affiliation(s)
- Yun-Dan Jia
- Department of Physiology, School of Medicine, Qingdao University, Qingdao, 266071 China
| | - Chang-Qin Liu
- Department of Physiology, School of Medicine, Qingdao University, Qingdao, 266071 China
| | - Ming Tang
- Department of Physiology, School of Medicine, Qingdao University, Qingdao, 266071 China
| | - Zheng-Yao Jiang
- Department of Physiology, School of Medicine, Qingdao University, Qingdao, 266071 China
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Feng X, Peeters TL, Tang M. Motilin activates neurons in the rat amygdala and increases gastric motility. Peptides 2007; 28:625-31. [PMID: 17222944 DOI: 10.1016/j.peptides.2006.11.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 11/19/2006] [Accepted: 11/20/2006] [Indexed: 12/11/2022]
Abstract
Motilin and motilin receptors have been found in most regions of the brain, including the amygdala, one of the most important parts of the limbic system. Our previous study found that administration of motilin in the hippocampus stimulates gastric motility. We now explore the effect of motilin in the amygdala on gastric motility. In conscious rats, gastric motility was recorded after microinjection of motilin, motilin receptor antagonist (GM-109) or a mixture of the two into the basomedial amygdala nucleus (BMA). In anesthetized rats the changes of spontaneous discharges of gastric distention sensitive neurons (GDSN) in the BMA were recorded after intracerebroventricular (i.c.v.) microinjection of motilin or GM-109. In conscious rats the amplitude of gastric contractions increased dose-dependently after microinjection of motilin in the BMA, and decreased after microinjection of GM-109. The excitatory or inhibitory effects induced by motilin or GM-109 alone, were weakened by microinjection of a mixture solution of both. The spontaneous discharge frequency of gastric distention excitatory neuron (GDEN) was mainly inhibited by i.c.v. microinjection of motilin but excited by GM-109. In contrast, the spontaneous discharge frequency of gastric distention inhibitory neuron (GDIN) was mainly excited by motilin, but inhibited by GM-109. Our findings suggest that motilin may regulate gastric motility by modulating neural pathways in the BMA.
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Affiliation(s)
- Xin Feng
- Department of Physiology, Medical College of Qingdao University, 38 Dengzhou Road, Qingdao, Shandong 266021, PR China.
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Takeshita E, Matsuura B, Dong M, Miller LJ, Matsui H, Onji M. Molecular characterization and distribution of motilin family receptors in the human gastrointestinal tract. J Gastroenterol 2006. [PMID: 16699856 DOI: 10.1007/s00535-00] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Motilin and ghrelin have been recognized as important endogenous regulators of gastrointestinal motor function in mammals, mediated respectively by the motilin receptor and by the closely related ghrelin receptor. The aims of this study were to explore the distribution of motilin and ghrelin receptors along the human gastrointestinal tract and to establish the molecular nature of the human motilin receptor. METHODS Post mortem and surgical human tissue specimens with no hemorrhage, necrosis, or tumor were obtained from various parts of the gastrointestinal tract. We analyzed levels of expression of mRNA for motilin and ghrelin receptors and examined their molecular identities. Portions of some specimens were also studied by immunohistochemistry for expression of the motilin and ghrelin receptor. RESULTS The long form of the motilin receptor, but not the short form, was expressed in all parts of the gastrointestinal tract, and expressed at higher levels in muscle than in mucosa. Motilin receptor immunoreactivity was present in muscle cells and the myenteric plexus, but not in mucosal or submucosal cells. In contrast, ghrelin receptor mRNA was expressed equally in all parts of the gastrointestinal tract, with similar levels of expression in mucosal and muscle layers. CONCLUSIONS Both the motilin and ghrelin receptors are expressed along the human gastrointestinal tract, but they have clearly distinct distributions in regard to both level and layer. The diffuse muscle expression of the motilin receptor, at both the levels of the gene and the protein product, along the entire gastrointestinal tract makes it a useful potential target for motilide drugs for dysmotility.
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Affiliation(s)
- Eiji Takeshita
- Third Department of Internal Medicine, Ehime University School of Medicine, Shitsukawa 454, Toon, 791-0295, Japan
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Takeshita E, Matsuura B, Dong M, Miller LJ, Matsui H, Onji M. Molecular characterization and distribution of motilin family receptors in the human gastrointestinal tract. J Gastroenterol 2006; 41:223-30. [PMID: 16699856 DOI: 10.1007/s00535-005-1739-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2005] [Accepted: 11/14/2005] [Indexed: 02/04/2023]
Abstract
BACKGROUND Motilin and ghrelin have been recognized as important endogenous regulators of gastrointestinal motor function in mammals, mediated respectively by the motilin receptor and by the closely related ghrelin receptor. The aims of this study were to explore the distribution of motilin and ghrelin receptors along the human gastrointestinal tract and to establish the molecular nature of the human motilin receptor. METHODS Post mortem and surgical human tissue specimens with no hemorrhage, necrosis, or tumor were obtained from various parts of the gastrointestinal tract. We analyzed levels of expression of mRNA for motilin and ghrelin receptors and examined their molecular identities. Portions of some specimens were also studied by immunohistochemistry for expression of the motilin and ghrelin receptor. RESULTS The long form of the motilin receptor, but not the short form, was expressed in all parts of the gastrointestinal tract, and expressed at higher levels in muscle than in mucosa. Motilin receptor immunoreactivity was present in muscle cells and the myenteric plexus, but not in mucosal or submucosal cells. In contrast, ghrelin receptor mRNA was expressed equally in all parts of the gastrointestinal tract, with similar levels of expression in mucosal and muscle layers. CONCLUSIONS Both the motilin and ghrelin receptors are expressed along the human gastrointestinal tract, but they have clearly distinct distributions in regard to both level and layer. The diffuse muscle expression of the motilin receptor, at both the levels of the gene and the protein product, along the entire gastrointestinal tract makes it a useful potential target for motilide drugs for dysmotility.
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Affiliation(s)
- Eiji Takeshita
- Third Department of Internal Medicine, Ehime University School of Medicine, Shitsukawa 454, Toon, 791-0295, Japan
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Wu M, Tang M, Adriaensen D, Depoortere I, Peeters TL, Timmermans JP. Central, but not peripheral application of motilin increases c-Fos expression in hypothalamic nuclei in the rat brain. Histochem Cell Biol 2005; 123:139-45. [PMID: 15714315 DOI: 10.1007/s00418-005-0763-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2004] [Accepted: 12/13/2004] [Indexed: 01/23/2023]
Abstract
Previous immunocytochemical studies have shown the presence of motilin-immunoreactive neurons in specific brain areas of rats and autoradiographic studies in rabbits demonstrated motilin-binding sites in the central nervous system as well. Therefore, the aim of this study was to determine the anatomical localisation and neurochemical features of neurons activated by central administration of motilin (Mo) in rats. One week after cannulation, an intracerebroventricular injection of Mo (ICV, 3 microg/6 mul 0.9% saline) was given. For comparative purposes, a group of animals received an intravenous injection of motilin (IV, 9 microg/300 mul 0.9% saline) or an equal volume of saline. Neuronal excitation was assessed by c-Fos immunocytochemistry and combined with immunostaining for neurotransmitter markers. In contrast to the IV motilin-treated animals, the ICV motilin-treated animals displayed a significant increase in c-Fos expression in the supraoptic nuclei (SO) and paraventricular nuclei of the hypothalamus (PVH). At the level of the dorsomedial, ventromedial and lateral hypothalamic nuclei, ICV administration of motilin did not induce changes in c-Fos expression. In addition, the cerebellum did not show c-Fos expression after ICV motilin administration either. These findings might suggest distinct pathways and actions of centrally released and systemic motilin, but, particularly in rodents, do not rule out the possibility that the effects seen in the SO and PVH after ICV application are aspecific in nature. At present, we cannot exclude the fact that the results observed with motilin in rodents are due to cross-interaction with other related (e.g. ghrelin) or not yet identified receptors.
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Affiliation(s)
- Mei Wu
- Medical College, University of Qingdao, 38 Dengzhou Road, 266021 Qingdao, People's Republic of China
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Pan W, Kastin AJ, Banks WA, Zadina JE. Effects of peptides: a cross-listing of peptides and their central actions published in the journal Peptides from 1994 through 1998. Peptides 1999; 20:1127-38. [PMID: 10499432 DOI: 10.1016/s0196-9781(99)00109-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Effects of peptides on the central nervous system are presented in two ways so as to provide a cross-listing. In the first table, the peptides are listed alphabetically. In the second table, the central nervous system effects are arranged alphabetically. No longer can there be any doubt that peptides affect the central nervous system, sometimes in several ways.
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Affiliation(s)
- W Pan
- VA Medical Center and Tulane University School of Medicine, Neuroscience Training Program and Department of Medicine, New Orleans, LA 70112-1262, USA.
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