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Abstract
The interaction between the peptide hormone motilin and bicelles has been investigated by pulsed field gradient-nuclear magnetic resonance methods and by the use of paramagnetic probes. Diffusion coefficients were measured for motilin, the phospholipids with and without motilin, and for tetramethylsilane. The results show that around 90% of motilin is bound to acidic bicelles and 84% of motilin is bound to neutral bicelles. It is found that the apparent bicelle size is reduced by the presence of motilin. This cannot be explained by changes in 1,2-dihexanoyl-sn-glycero-3-phosphatidylcholine solubility. The use of paramagnetic agents to investigate the position of motilin shows that the turn in the N-terminus of motilin is inserted into the bicelle, while the helix most likely resides within the head-group layer.
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Affiliation(s)
- August Andersson
- Department of Biochemistry and Biophysics, Arrhenius Laboratory, Stockholm University, 10691, Stockholm, Sweden
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152
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SASAKI N, YAMADA H, HARA S. Medicinal Treatment to Equine Gastrointestinal Dysfunctions. J Equine Sci 2003. [DOI: 10.1294/jes.14.37] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Naoki SASAKI
- Department of Veterinary Surgery, Obihiro University of Agriculture & Veterinary Medicine
| | - Haruo YAMADA
- Department of Veterinary Surgery, Obihiro University of Agriculture & Veterinary Medicine
| | - Shigeo HARA
- Veterinary Surgery, Faculty of Agriculture, Iwate University
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153
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Asakawa A, Inui A, Ueno N, Makino S, Uemoto M, Fujino MA, Kasuga M. Ob/ob mice as a model of delayed gastric emptying. J Diabetes Complications 2003; 17:27-8. [PMID: 12505753 DOI: 10.1016/s1056-8727(02)00198-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Diabetic gastroparesis is a well-recognized delay of gastric emptying in diabetic patients. We assessed the gastric emptying rate in ob/ob mice, a genetic model of obesity and diabetes. The basal gastric emptying rate in 22- to 27-week-old ob/ob mice was significantly lower than that in 10- to 11-week-old ob/ob mice (P<.01). Our results indicate that the ob/ob mice are a useful model not only of glucose intolerance but also of delayed gastric emptying as a diabetic complication.
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Affiliation(s)
- Akihiro Asakawa
- Department of Clinical Molecular Medicine, Division of Diabetes, Digestive and Kidney Diseases, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Japan
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154
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Stanghellini V, De Ponti F, De Giorgio R, Barbara G, Tosetti C, Corinaldesi R. New developments in the treatment of functional dyspepsia. Drugs 2003; 63:869-92. [PMID: 12678573 DOI: 10.2165/00003495-200363090-00003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Functional dyspepsia is a clinical syndrome defined by chronic or recurrent pain or discomfort in the upper abdomen of unknown origin. Although generally accepted, investigators differently interpret this definition and clinical trials are often biased by inhomogeneous inclusion criteria. The poorly defined multifactorial pathogenesis of dyspeptic symptoms has hampered efforts to develop effective treatments. A general agreement exists on the irrelevant role played by Helicobacter pylori in the pathophysiology of functional dyspepsia. Gastric acid secretion is within normal limits in patients with functional dyspepsia but acid related symptoms may arise in a subgroup of them. Proton pump inhibitors appear to be effective in this subset of patients with dyspepsia. Non-painful dyspeptic symptoms are suggestive of underlying gastrointestinal motor disorders and such abnormalities can be demonstrated in a substantial proportion of patients. Postprandial fullness and vomiting have been associated with delayed gastric emptying of solids, and early satiety and weight loss to postcibal impaired accommodation of the gastric fundus. Prokinetics have been shown to exert beneficial effects, at least in some patients with dyspepsia. In contrast, drugs enhancing gastric fundus relaxation have been reported to improve symptoms, although conflicting results have also been published. An overdistended antrum may also generate symptoms, but its potential pathogenetic role and the effects of drugs on this abnormality have never been investigated formally. Visceral hypersensitivity plays a role in some dyspeptic patients and this abnormality is also a potential target for treatment. Both chemo- and mechanoreceptors can trigger hyperalgesic responses. Psychosocial abnormalities have been consistently found in functional digestive syndromes, including dyspepsia. Although useful in patients with irritable bowel syndromes (IBS), antidepressants have been only marginally explored in functional dyspepsia. Among the new potentially useful agents for the treatment of functional dyspepsia, serotonin 5-HT(4) receptor agonists have been shown to exert a prokinetic effect. Unlike motilides, 5-HT(4) receptor agonists do not appear to increase the gastric fundus tone and this may contribute to improve symptoms. 5-HT(3) receptor antagonists have been investigated mainly in the IBS and the few studies performed in functional dyspepsia have provided conflicting results. Also, kappa-opioid receptor agonists might be useful for functional digestive syndromes because of their antinociceptive effects, but available results in functional dyspepsia are scanty and inconclusive. Other receptors that represent potential clinical targets for antagonists include purinoceptors (i. e., P2X2/3 receptors), NMDA receptors (NR2B subtype), protease-activated receptor-2, the vanilloid receptor-1, tachykinin receptors (NK(1)/NK(2)) and cholecystokinin (CCK)(1) receptors.
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Affiliation(s)
- Vincenzo Stanghellini
- Department of Internal Medicine and Gastroenterology, University of Bologna, Bologna, Italy.
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155
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Koenig JB, Cote N, LaMarre J, Harris WH, Trout DR, Kenney DG, Monteith G. Binding of radiolabeled porcine motilin and erythromycin lactobionate to smooth muscle membranes in various segments of the equine gastrointestinal tract. Am J Vet Res 2002; 63:1545-50. [PMID: 12428665 DOI: 10.2460/ajvr.2002.63.1545] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
OBJECTIVE To identify and characterize motilin receptors in equine duodenum, jejunum, cecum, and large colon and to determine whether erythromycin lactobionate competes with porcine motilin for binding to these receptors. SAMPLE POPULATION Specimens of various segments of the intestinal tracts of 4 adult horses euthanatized for reasons unrelated to gastrointestinal tract disease. PROCEDURE Cellular membranes were prepared from smooth muscle tissues of the duodenum, jejunum, pelvic flexure, and cecum. Affinity and distribution of motilin binding on membrane preparations were determined by use of 125I-labeled synthetic porcine motilin. Displacement studies were used to investigate competition between 125I-labeled synthetic porcine motilin and erythromycin lactobionate for binding to motilin receptors in various segments of bowel. RESULTS Affinity of 125I-labeled synthetic porcine motilin for the equine motilin receptor was estimated to be 6.1nM. A significantly higher number of motilin receptors was found in the duodenum than in the pelvic flexure and cecum. The jejunum had a significantly higher number of motilin receptors than the cecum. Erythromycin lactobionate displacement of 125I-labeled porcine motilin from the equine motilin receptor did not differ significantly among various segments of bowel. CONCLUSIONS AND CLINICAL RELEVANCE Motilin receptors were found in the duodenum, jejunum, pelvic flexure, and cecum of horses. The highest number of motilin receptors was in the duodenum, and it decreased in more distal segments of bowel. Erythromycin lactobionate competed with motilin binding in the equine gastrointestinal tract. This suggests that 1 of the prokinetic actions of erythromycin in horses is likely to be secondary to binding on motilin receptors.
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Affiliation(s)
- Judith B Koenig
- Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Canada
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156
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Takayama I, Horiguchi K, Daigo Y, Mine T, Fujino MA, Ohno S. The interstitial cells of Cajal and a gastroenteric pacemaker system. ARCHIVES OF HISTOLOGY AND CYTOLOGY 2002; 65:1-26. [PMID: 12002607 DOI: 10.1679/aohc.65.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In spite of a claim by Kobayashi (1990) that they do not correspond to the cells originally depicted by CAJAL, a particular category of fibroblast-like cells have been identified in the gut by electron microscopy (Faussone-Pellegrini, 1977; Thuneberg, 1980) and by immunohistochemistry for Kit protein (Maeda et al., 1992) under the term of the "interstitial cells of Cajal (ICC)". Generating electrical slow waves, the ICC are intercalated between the intramural neurons and the effector smooth muscular cells, to form a gastroenteric pacemaker system. ICC at the level of the myenteric plexus (IC-MY) are multipolar cells forming a reticular network. The network of IC-MY which is believed to be the origin of electrical slow waves is morphologically independent from but associated with the myenteric plexus. On the other hand, intramuscular ICC (IC-IM) usually have spindle-shaped contours arranged in parallel with the bulk smooth muscle cells. Associated with nerve bundles and blood vessels, the IC-IM possess receptors for neurotransmitters and such circulating hormones as cholecystokinin, suggesting their roles in neuromuscular and hormone-muscular transmissions. In addition, gap junctions connect the IC-MY and IC-IM, thereby realizing the electrically synchronized integrity of ICC as a pacemaker system in the gut. The smooth muscle cells are also coupled with ICC via gap junctions, and the functional unit thus formed enables rhythmically synchronized contractions and relaxations. It has recently been found that a lack of Kit-expressing cells may induce hyper-contractility of the tunica muscularis in vitro, whereas a decrease in Kit expression within the muscle wall causes dysmotility-like symptoms in vivo. The pacemaker system in the gut thus seems to play a critical role in the maintenance of both moderate and normal motility of the digestive tract. A loss of Kit positive cells has been detected in several diseases with an impaired motor activity, including diabetic gastroenteropathy. Pathogenesis of these diseases is thought to be accounted for by impaired slow waves and neuromuscular transmissions; a pacemaker disorder may possibly induce a dysmotility-like symptom called 'gastroenteric arrhythmia'. A knowledge of the structure and function of the ICC and the pacemaker system provides a basis for clarifying the normal mechanism and the pathophysiology of motility in the digestive tract.
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Affiliation(s)
- Ichiro Takayama
- Department of Anatomy, Yamanashi Medical University School of Medicine, Japan.
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157
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Haramura M, Okamachi A, Tsuzuki K, Yogo K, Ikuta M, Kozono T, Takanashi H, Murayama E. Design and synthesis of motilin antagonists derived from the [1-4] fragment of porcine motilin. J Med Chem 2002; 45:670-5. [PMID: 11806718 DOI: 10.1021/jm010332u] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of cyclic peptides having the general structure H-Phe-c[-N(epsilon)-Lys-X-NH-(CH(2))(n)-CO-] were designed on the basis of structure-activity relationship studies of motilin. All were motilin antagonists. The cyclic peptides, in which X is a 3-tert-butyl-substituted tyrosine residue (H-Phe-c[-N(epsilon)-Lys-Tyr(3-tBu)-beta Ala-] (3), H-Phe-c[-N(epsilon)-Lys-Tyr(3-tBu)-Gly-] (6), H-Phe-c[-N(epsilon)-Lys-Tyr(3-tBu)-Abu-] (7), and H-Phe-c[-N(epsilon)-Lys-Tyr(3-tBu)-Ahx-] (8)) showed potent motilin receptor antagonistic activity in the rabbit smooth muscle (pA(2) > 7). The 3-tert-butyl Tyr was found to be the moiety responsible for enhanced binding to the motilin receptor, while the size of the ring had little importance.
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Affiliation(s)
- Masayuki Haramura
- Fuji-Gotemba Research Laboratories, Chugai Pharmaceutical Co. Ltd., 1-135 Komakado, Gotemba-shi, Shizuoka 412-8513, Japan.
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158
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Nogami K, Nishikubo T, Minowa H, Uchida Y, Kamitsuji H, Takahashi Y. Intravenous low-dose erythromycin administration for infants with feeding intolerance. Pediatr Int 2001; 43:605-10. [PMID: 11737737 DOI: 10.1046/j.1442-200x.2001.01448.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND This study was undertaken to determine the efficacy of low-dose intravenous erythromycin (EM) administration in infants with feeding intolerance. METHODS The subjects were 26 infants who would not accept enteral feeding within 5 days after birth. Fourteen infants (gestational age: 30.6+/-5.4 weeks and birthweight: 1466+/-825 g) were given EM intravenously at a dose of 1 mg/kg, three times daily (EM group). Doses were increased to 2 mg/kg in five infants who showed a poor response. Twelve infants (gestational age: 30.5+/-5.0 weeks and birthweight: 1317+/-672 g) were observed without EM administration (non-EM group). Blood concentrations of EM at 2 h after administration were measured on 8 (+/-2) days after the start of EM administration in the EM group. RESULTS Digestive perturbations and intestinal gasless and/or atonic shadows on X-ray findings markedly improved in the EM group soon after the treatment. Comparing the EM group and non-EM group, the postnatal ages at the start of successful enteral feeding were 9.1+/-3.2 days and 14.0+/-4.1 days, respectively (P<0.01). The postnatal ages at feeding of 100 mL/kg per day were 15.2+/-4.0 days and 23.4+/-6.2 days, respectively (P<0.01). The blood EM concentrations of 1 mg/kg and 2 mg/kg were 0.29+/-0.28 microg/mL and 0.57+/-0.20 microg/mL, respectively (P<0.05). No adverse effect on cardiac status or in blood examinations was observed in any infant in the EM group. CONCLUSION These results suggest that intravenous low-dose EM administration is a useful and safe treatment of feeding intolerance in infants including extremely low-birthweight infants.
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Affiliation(s)
- K Nogami
- Neonatal Intensive Care Unit, Perinatal Medical Center, Nara Prefectural Hospital, 1-30-1 Hiramatsu-cho, Nara-City, Nara, 631-0846, Japan
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159
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Coulie B, Matsuura B, Dong M, Hadac EM, Pinon DI, Feighner SD, Howard AD, Miller LJ. Identification of peptide ligand-binding domains within the human motilin receptor using photoaffinity labeling. J Biol Chem 2001; 276:35518-22. [PMID: 11461914 DOI: 10.1074/jbc.m104489200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cDNA encoding the human motilin receptor was recently cloned and found to represent a G protein-coupled receptor that is structurally related to the growth hormone secretagogue receptors. Together, these represent a new Class I receptor family. Our aim in the present work is to gain insight into the molecular basis of binding of motilin to its receptor using photoaffinity labeling. To achieve this, we developed a Chinese hamster ovary cell line that overexpressed functional motilin receptor (CHO-MtlR; 175,000 sites per cell, with K(i) = 2.3 +/- 0.4 nm motilin and EC(50) = 0.3 +/- 0.1 nm motilin) and a radioiodinatable peptide analogue of human motilin that incorporated a photolabile p-benzoyl-l-phenylalanine (Bpa) residue into its pharmacophoric domain. This probe, [Bpa(1),Ile(13)]motilin, was a full agonist at the motilin receptor that increased intracellular calcium in a concentration-dependent manner (EC(50) = 1.5 +/- 0.4 nm). This photolabile ligand bound specifically and with high affinity to the motilin receptor (K(i) = 12.4 +/- 1.0 nm), and covalently labeled that molecule within its M(r) = 45,000 deglycosylated core. Cyanogen bromide cleavage demonstrated its covalent attachment to fragments of the receptor having apparent M(r) = 6,000 and M(r) = 31,000. These were demonstrated to represent fragments that included both the first and the large second extracellular loop domains, with the latter representing a unique structural feature of this receptor. The spatial approximation of the pharmacophoric domain of motilin with these receptor domains support their functional importance as well.
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Affiliation(s)
- B Coulie
- Center for Basic Research in Digestive Diseases, Departments of Internal Medicine and Biochemistry/Molecular Biology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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160
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Affiliation(s)
- A Inui
- Division of Diabetes, Digestive and Kidney Diseases, Department of Clinical Molecular Medicine, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
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161
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Briejer MR, Bosmans JP, Van Daele P, Jurzak M, Heylen L, Leysen JE, Prins NH, Schuurkes JA. The in vitro pharmacological profile of prucalopride, a novel enterokinetic compound. Eur J Pharmacol 2001; 423:71-83. [PMID: 11438309 DOI: 10.1016/s0014-2999(01)01087-1] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Prucalopride is a novel enterokinetic compound and is the first representative of the benzofuran class. We set out to establish its pharmacological profile in various receptor binding and organ bath experiments. Receptor binding data have demonstrated prucalopride's high affinity to both investigated 5-HT(4) receptor isoforms, with mean pK(i) estimates of 8.60 and 8.10 for the human 5-HT(4a) and 5-HT(4b) receptor, respectively. From the 50 other binding assays investigated in this study only the human D(4) receptor (pK(i) 5.63), the mouse 5-HT(3) receptor (pK(i) 5.41) and the human sigma(1) (pK(i) 5.43) have shown measurable affinity, resulting in at least 290-fold selectivity for the 5-HT(4) receptor. Classical organ bath experiments were done using isolated tissues from the rat, guinea-pig and dog gastrointestinal tract, using various protocols. Prucalopride was a 5-HT(4) receptor agonist in the guinea-pig colon, as it induced contractions (pEC(50)=7.48+/-0.06; insensitive to a 5-HT(2A) or 5-HT(3) receptor antagonist, but inhibited by a 5-HT(4) receptor antagonist) as well as the facilitation of electrical stimulation-induced noncholinergic contractions (blocked by a 5-HT(4) receptor antagonist). Furthermore, it caused relaxation of a rat oesophagus preparation (pEC(50)=7.81+/-0.17), in a 5-HT(4) receptor antagonist sensitive manner. Prucalopride did not cause relevant inhibition of 5-HT(2A), 5-HT(2B), or 5-HT(3), motilin or cholecystokinin (CCK(1)) receptor-mediated contractions, nor nicotinic or muscarinic acetylcholine receptor-mediated contractions, up to 10 microM. It is concluded that prucalopride is a potent, selective and specific 5-HT(4) receptor agonist. As it is intended for treatment of intestinal motility disorders, it is important to note that prucalopride is devoid of anti-cholinergic, anticholinesterase or nonspecific inhibitory activity and does not antagonise 5-HT(2A), 5-HT(2B) and 5-HT(3) receptors or motilin or CCK(1) receptors.
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Affiliation(s)
- M R Briejer
- Department of Gastrointestinal Pharmacology, Janssen Research Foundation, Turnhoutseweg 30, 2340 Beerse, Belgium
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162
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Kihara N, Fujimura M, Yamamoto I, Itoh E, Inui A, Fujimiya M. Effects of central and peripheral urocortin on fed and fasted gastroduodenal motor activity in conscious rats. Am J Physiol Gastrointest Liver Physiol 2001; 280:G406-19. [PMID: 11171623 DOI: 10.1152/ajpgi.2001.280.3.g406] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Since few previous studies have examined the effects of urocortin on physiological fed and fasted gastrointestinal motility, we administered urocortin intracerebroventricularly (icv) or intravenously (iv) in freely moving conscious rats and examined the changes in antral and duodenal motility. Icv and iv injection of urocortin disrupted fasted motor patterns of gastroduodenal motility, which were replaced by fed-like motor patterns. When urocortin was given icv and iv in the fed state, the motor activity remained like the fed patterns but % motor index (%MI) was decreased in the antrum and increased in the duodenum. Increase in the %MI in the duodenum induced by urocortin was shown as a nonpropagated event, since the transit of nonnutrient contents in the duodenum was decreased by icv and iv injection of urocortin. Changes in the gastroduodenal motility induced by icv injection of urocortin were abolished in animals with truncal vagotomy but not altered in animals with mechanical sympathectomy, suggesting that the vagal pathway may mediate the central action of urocortin. Neither urocortin antiserum nor alpha-helical CRF-(9-41) affected fed and fasted gastroduodenal motility, suggesting that endogenous urocortin is not involved in regulation of basal gastroduodenal motility.
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Affiliation(s)
- N Kihara
- Department of Surgery, Shiga University of Medical Science, Otsu, Japan
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163
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Ueno N, Inui A, Asakawa A, Takao F, Ichibangase A, Komatsu Y, Kasuga M. Erythromycin administration before sleep is effective in decreasing fasting hyperglycemia in type 2 diabetic patients. Diabetes Care 2001; 24:607. [PMID: 11289494 DOI: 10.2337/diacare.24.3.607] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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164
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Asakawa A, Inui A, Kaga T, Yuzuriha H, Nagata T, Ueno N, Makino S, Fujimiya M, Niijima A, Fujino MA, Kasuga M. Ghrelin is an appetite-stimulatory signal from stomach with structural resemblance to motilin. Gastroenterology 2001; 120:337-45. [PMID: 11159873 DOI: 10.1053/gast.2001.22158] [Citation(s) in RCA: 826] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND & AIMS : Ghrelin, an endogenous ligand for growth hormone secretagogue receptor, was recently identified in the rat stomach. We examined the effects of the gastric peptide ghrelin on energy balance in association with leptin and vagal nerve activity. METHODS : Food intake, oxygen consumption, gastric emptying, and hypothalamic neuropeptide Y (NPY) messenger RNA expression were measured after intra-third cerebroventricular or intraperitoneal injections of ghrelin in mice. The gastric vagal nerve activity was recorded after intravenous administration in rats. Gastric ghrelin gene expression was assessed by Northern blot analysis. Repeated coadministration of ghrelin and interleukin (IL)-1 beta was continued for 5 days. RESULTS : Ghrelin exhibited gastroprokinetic activity with structural resemblance to motilin and potent orexigenic activity through action on the hypothalamic neuropeptide Y (NPY) and Y(1) receptor, which was lost after vagotomy. Ghrelin decreased gastric vagal afferent discharge in contrast to other anorexigenic peptides that increased the activity. Ghrelin gene expression in the stomach was increased by fasting and in ob/ob mice, and was decreased by administration of leptin and IL-1 beta. Peripherally administered ghrelin blocked IL-1 beta-induced anorexia and produced positive energy balance by promoting food intake and decreasing energy expenditure. CONCLUSIONS : Ghrelin, which is negatively regulated by leptin and IL-1 beta, is secreted by the stomach and increases arcuate NPY expression, which in turn acts through Y(1) receptors to increase food intake and decrease energy expenditure. Gastric peptide ghrelin may thus function as part of the orexigenic pathway downstream from leptin and is a potential therapeutic target not only for obesity but also for anorexia and cachexia.
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Affiliation(s)
- A Asakawa
- Second Department of Internal Medicine, Kobe University School of Medicine, Kobe, Japan
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165
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Haramura M, Okamachi A, Tsuzuki K, Yogo K, Ikuta M, Kozono T, Takanashi H, Murayama E. Design and synthesis of N-terminal cyclic motilin partial peptides: a novel pure motilin antagonist. Chem Pharm Bull (Tokyo) 2001; 49:40-3. [PMID: 11201222 DOI: 10.1248/cpb.49.40] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Motilin antagonist was designed and synthesized on the basis of the structure-activity relationship analysis of porcine motilin that we reported recently. The drug design was performed on a specific concept to reduce a flexibility of peptide conformation of porcine motilin partial peptide by its cyclization. The cyclic peptide was synthesized using Boc (tert-butyloxycarbonyl) solid phase methodology, followed by cyclization using the azide procedure, and tested for the binding activity to motilin receptor and smooth muscle contractile activity. The cyclic peptides 3, 4, and 5 showed antagonistic property on contraction assay (pA2 [the negative logarithm of molar concentration of antagonist causing a 2-hold shift to the right of the concentration-response curve for motilin]: 4.5, 4.34, and 4.04, respectively, in rabbit duodenum) and no contractile activity even at high concentration.
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Affiliation(s)
- M Haramura
- Fuji-Gotemba Research Laboratories, Chugai Pharmaceutical Co. Ltd., Shizuoka, Japan.
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166
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Affiliation(s)
- L J Miller
- Center for Basic Research in Digestive Diseases, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
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167
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Masuda Y, Tanaka T, Inomata N, Ohnuma N, Tanaka S, Itoh Z, Hosoda H, Kojima M, Kangawa K. Ghrelin stimulates gastric acid secretion and motility in rats. Biochem Biophys Res Commun 2000; 276:905-8. [PMID: 11027567 DOI: 10.1006/bbrc.2000.3568] [Citation(s) in RCA: 645] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ghrelin, a novel growth-hormone-releasing peptide, was discovered in rat and human stomach tissues. However, its physiological and pharmacological actions in the gastric function remain to be determined. Therefore, we studied the effects of rat ghrelin on gastric functions in urethane-anesthetized rats. Intravenous administrations of rat ghrelin at 0.8 to 20 microgram/kg dose-dependently increased not only gastric acid secretion measured by a lumen-perfused method, but also gastric motility measured by a miniature balloon method. The maximum response in gastric acid secretion was almost equipotent to that of histamine (3 mg/kg, i.v.). Moreover, these actions were abolished by pretreatment with either atropine (1 mg/kg, s.c.) or bilateral cervical vagotomy, but not by a histamine H(2)-receptor antagonist (famotidine, 1 mg/kg, s.c.). These results taken together suggest that ghrelin may play a physiological role in the vagal control of gastric function in rats.
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Affiliation(s)
- Y Masuda
- Suntory Institute for Medicinal Research & Development, 2716-1 Kurakake, Akaiwa, Chiyoda-machi, Ohra-gun, Gunma, 370-0503, Japan
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168
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Tomasetto C, Karam SM, Ribieras S, Masson R, Lefèbvre O, Staub A, Alexander G, Chenard MP, Rio MC. Identification and characterization of a novel gastric peptide hormone: the motilin-related peptide. Gastroenterology 2000; 119:395-405. [PMID: 10930375 DOI: 10.1053/gast.2000.9371] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS This study looked for new proteins with expression restricted to the gastric epithelium that may provide insight to the differentiation and function of the gastric unit. METHODS A novel complementary DNA was isolated and sequenced, and its expression was examined in mouse tissues at both messenger RNA and protein levels. Subcellular localization was studied using immunoelectron microscopy. The posttraductional processing of the protein was analyzed in vitro by protein microsequencing and in vivo by Western blotting. RESULTS We identified a novel protein that is mainly expressed by the secretory granules of the stomach enteroendocrine cells. This protein has sequence similarity with prepromotilin, the precursor of the motilin hormone and the motilin-associated peptide. As for the prepromotilin, a posttraductional maturation leads to a secreted peptide that is further cleaved at a dibasic site and gives rise to the motilin-related peptide (MTLRP) and MTLRP-associated peptide. CONCLUSIONS We have identified and characterized a novel gene encoding the preproMTLRP protein. MTLRP presents similarity to motilin and is specifically expressed by enteroendocrine cells of the stomach and therefore represents a novel hormone.
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Affiliation(s)
- C Tomasetto
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS/INSERM Unité 184/ULP, Strasbourg, France
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169
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Tsukamoto K, Mizutani M, Yamano M, Tagi Y, Takeda M. The effect of SK-896 on post-operative ileus in dogs: gastrointestinal motility pattern and transit. Eur J Pharmacol 2000; 401:97-107. [PMID: 10915842 DOI: 10.1016/s0014-2999(00)00446-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The aim of this study was to investigate the effect of SK-896 (Phe-Val-Pro-Ile-Phe-Thr-Try-Gly-Glu-Leu-Gln-Arg-Leu-Gln-Glu-Lys-Glu- Arg-Asn-Lys-Gly-Gln-Hse), a new motilin analogue, on gastrointestinal motility and transit in dogs with post-operative ileus, and to compare the effects of this agent on these parameters with the effects of prostaglandin F(2alpha), a well-known gastroprokinetic agent. We used chronically implanted force transducers to measure motility and radiography of radio-opaque markers to measure transit. Infusion of SK-896 1 microgram/kg/h, for 20 min twice a day induced interdigestive migrating contractions-like motility. Infusion of prostaglandin F(2alpha), 20 microgram/kg/h, for 1 h twice a day induced continuous contractions in the distal part of the small intestine. The time of first appearance of interdigestive migrating contractions in the stomach (gastric-interdigestive migrating contractions) and the gastric emptying time of the solid marker with the administration of SK-896 were significantly less than those noted with the administration of prostaglandin F(2alpha). It appears that gastric-interdigestive migrating contractions play an important role in the transit of substances, especially solid substances, in the gastrointestinal tract. We conclude that SK-896, which induced gastric-interdigestive migrating contractions, is effective to induce early recovery from post-operative ileus.
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Affiliation(s)
- K Tsukamoto
- Central Research Laboratory, Sanwa Kagaku Kenkyusho Co., Ltd., 363 Siosaki Hokusei-cho, Inabe-gun, 511-0406, Mie, Japan.
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170
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Tsukamoto K, Kuboyama N, Yamano M, Nakazawa T, Suzuki T. In vitro pharmacological profile of SK-896, a new human motilin analogue. Pharmacology 2000; 60:128-35. [PMID: 10754449 DOI: 10.1159/000028357] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
SK-896 ([Leu(13)]motilin-Hse) is a new human motilin analogue synthesized by Escherichia coli using a biotechnological method. We investigated the binding of SK-896 to motilin receptors and the contractile effect of SK-896 on smooth muscle preparations isolated from the gastrointestinal tract and various regional organs in order to clarify its in vitro pharmacological profile. SK-896 inhibited the binding of (125)I-human motilin to rabbit gastroduodenal motilin receptors with the same potency as unlabeled human motilin. The IC(50) values of SK-896 and human motilin were 3.5 +/- 1.5 and 3.1 +/- 1.8 nmol/l, respectively. The K(d) of human motilin was 3.0 +/- 1.5 nmol/l, and the Ki of SK-896 was 3.4 +/- 1.5 nmol/l. SK-896 induced contraction of smooth muscle preparations isolated from rabbit duodenum in a concentration-dependent manner. However, there was no effect of SK-896 on duodenal preparations isolated from the dog and the rat. SK-896 thus exhibited species specificity in its contractile effect. We next investigated the effect of SK-896 on various smooth muscle preparations isolated from rabbit gastrointestinal tract, trachea, bladder, gallbladder, uterus, vas deferens and artery. Results showed that SK-896 induced contraction of smooth muscle preparations isolated from gastrointestinal tract, with potencies in the order duodenum > gastric pylorus = jejunum = descending colon > ascending colon >/= ileum. However, there was no effect of SK-896 on smooth muscle preparations from gastric fundus and other regional organs. SK-896 thus exhibited regional specificity in its contractile effect. Moreover, the effects of SK-896 on smooth muscle preparations from rabbit duodenum were the same as those of human motilin, and were not inhibited by pretreatment with tetrodotoxin and atropine but were inhibited by verapamil. These findings indicate that SK-896 has the same pharmacological profile as human motilin. They suggest that SK-896 acts on gastrointestinal smooth muscle isolated from rabbit directly and specifically.
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Affiliation(s)
- K Tsukamoto
- Pharmaceutical Laboratory, Sanwa Kagaku Kenkyusho Co., Ltd., Mie, Japan.
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171
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Fujimiya M, Itoh E, Kihara N, Yamamoto I, Fujimura M, Inui A. Neuropeptide Y induces fasted pattern of duodenal motility via Y(2) receptors in conscious fed rats. Am J Physiol Gastrointest Liver Physiol 2000; 278:G32-8. [PMID: 10644559 DOI: 10.1152/ajpgi.2000.278.1.g32] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Neuropeptide Y (NPY), a 36-amino acid peptide abundantly expressed in the brain, has been implicated in the regulation of feeding and visceral functions. The present study was designed to investigate whether or not NPY specifically regulates duodenal motility. The manometric method was used to measure duodenal motility in conscious, freely moving rats. The rat duodenum showed phasic contractions mimicking the migrating motor complex in the fasted state that were replaced by irregular contractions after the ingestion of food. NPY powerfully affected the contractile activity after intracerebroventricular (i.c.v.) administration, changing fed (postprandial) patterns into phasic contractions characterized as fasted (interdigestive) patterns. This effect was mediated via receptors with pharmacological profiles similar to rat Y(2) and Y(4) receptors, although neither Y(1) nor Y(5) agonists had any effects on motility despite potent feeding-stimulatory effects. Immunoneutralization with anti-NPY antiserum administered i.c.v. abolished fasted patterns and induced fed-like motor activities. An i.c.v. dose of peptide YY produced a different effect from NPY, with increase in the motor activities of both fed and fasted patterns. These results indicate that fasted and fed motor activities are regulated processes and that NPY induces fasted activity through Y(2), and possibly Y(4), receptors, which may represent an integrated mechanism linked to the onset of feeding behavior.
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Affiliation(s)
- M Fujimiya
- Department of Anatomy, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
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172
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Honein MA, Paulozzi LJ, Himelright IM, Lee B, Cragan JD, Patterson L, Correa A, Hall S, Erickson JD. Infantile hypertrophic pyloric stenosis after pertussis prophylaxis with erythromcyin: a case review and cohort study. Lancet 1999; 354:2101-5. [PMID: 10609814 DOI: 10.1016/s0140-6736(99)10073-4] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND In February, 1999, a local US health department identified a cluster of pertussis cases among neonates born at a community hospital and recommended oral erythromycin for post-exposure prophylaxis for about 200 neonates born at that hospital between Feb 1 and Feb 24, 1999. We investigated a cluster of seven cases of infantile hypertrophic pyloric stenosis (IHPS) that occurred the following month among the neonates who had received erythromycin. METHODS We obtained a masked, independent review of the IHPS ultrasonography diagnoses, calculated the monthly IHPS incidence, and compared index and historical (1998-99) IHPS cases with respect to several characteristics including erythromycin exposure. We used a retrospective cohort of infants born in January and February, 1999, to investigate further erythromycin exposure and development of IHPS. FINDINGS An independent review confirmed the ultrasonographic diagnoses of all seven index IHPS cases. All index cases versus none of the historical IHPS cases had been given erythromycin for pertussis prophylaxis. The IHPS rate for infants born in the hospital in February, 1999, was 32.3 per 1000 liveborn infants, representing nearly a seven-fold increase over 1997-98 (relative risk 6.8 [95% CI 3.0-15.7]). Among infants born in January and February, 1999, erythromycin was associated with IHPS (absolute risk 4.5%, relative risk infinity [1.7-infinity]). INTERPRETATION Neonates receiving oral erythromycin may have an increased risk of IHPS. The risks and benefits of erythromycin for neonatal pertussis prophylaxis should be re-evaluated, and caution should be used in defining risk groups for prophylaxis.
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Affiliation(s)
- M A Honein
- Division of Birth Defects, Child Development, and Disability and Health, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341-3724, USA.
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173
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Tonini M, De Ponti F, Di Nucci A, Crema F. Review article: cardiac adverse effects of gastrointestinal prokinetics. Aliment Pharmacol Ther 1999; 13:1585-91. [PMID: 10594392 DOI: 10.1046/j.1365-2036.1999.00655.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Gastrointestinal prokinetics, such as metoclopramide, cisapride and levosulpiride, are widely used for the management of functional gut disorders. Recently, several studies have shown that cisapride (a partial 5-HT4 receptor agonist) can induce dose-dependent cardiac adverse effects, including lengthening of the electrocardiographic QT interval, syncopal episodes and ventricular dysrhythmias. Until recently, it was not clear whether these effects were dependent on 5-HT4 receptor activation or related to peculiar characteristics in the molecular structure of single agents within the benzamide class. Experimental evidence now favours the second hypothesis: cisapride possesses Class III antiarrhythmic properties and prolongs the action potential duration through blockade of distinct voltage-dependent K+ channels, thus delaying cardiac repolarization and prolonging the QT interval. Patients at risk of cardiac adverse effects are children, subjects with idiopathic, congenital or acquired long QT syndrome and, in particular, those receiving concomitant medication with Class III antiarrhythmic agents, some H1-receptor antagonists (e.g. terfenadine), or drugs such as azole antifungals (e.g. ketoconazole, itraconazole, miconazole and fluconazole) and macrolide antibacterials (e.g. erythromycin, clarithrod-mycin and troleandomycin), which can inhibit cisapride metabolism by interfering with the CYP3A4 isoenzyme.
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Affiliation(s)
- M Tonini
- Department of Internal Medicine and Therapeutics, Section of Experimental and Clinical Pharmacology, University of Pavia, Pavia, Italy.
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174
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Feighner SD, Tan CP, McKee KK, Palyha OC, Hreniuk DL, Pong SS, Austin CP, Figueroa D, MacNeil D, Cascieri MA, Nargund R, Bakshi R, Abramovitz M, Stocco R, Kargman S, O'Neill G, Van Der Ploeg LH, Evans J, Patchett AA, Smith RG, Howard AD. Receptor for motilin identified in the human gastrointestinal system. Science 1999; 284:2184-8. [PMID: 10381885 DOI: 10.1126/science.284.5423.2184] [Citation(s) in RCA: 273] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Motilin is a 22-amino acid peptide hormone expressed throughout the gastrointestinal (GI) tract of humans and other species. It affects gastric motility by stimulating interdigestive antrum and duodenal contractions. A heterotrimeric guanosine triphosphate-binding protein (G protein)-coupled receptor for motilin was isolated from human stomach, and its amino acid sequence was found to be 52 percent identical to the human receptor for growth hormone secretagogues. The macrolide antibiotic erythromycin also interacted with the cloned motilin receptor, providing a molecular basis for its effects on the human GI tract. The motilin receptor is expressed in enteric neurons of the human duodenum and colon. Development of motilin receptor agonists and antagonists may be useful in the treatment of multiple disorders of GI motility.
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MESH Headings
- Alternative Splicing
- Amino Acid Sequence
- Base Sequence
- Binding Sites
- Calcium/metabolism
- Cell Line
- Chromosome Mapping
- Chromosomes, Human, Pair 13
- Cloning, Molecular
- Colon/metabolism
- Erythromycin/metabolism
- GTP-Binding Proteins/metabolism
- Gastric Mucosa/metabolism
- Humans
- In Situ Hybridization
- Intestine, Small/metabolism
- Ligands
- Molecular Sequence Data
- Motilin/analogs & derivatives
- Motilin/metabolism
- Receptors, Gastrointestinal Hormone/chemistry
- Receptors, Gastrointestinal Hormone/genetics
- Receptors, Gastrointestinal Hormone/metabolism
- Receptors, Neuropeptide/chemistry
- Receptors, Neuropeptide/genetics
- Receptors, Neuropeptide/metabolism
- Thyroid Gland/metabolism
- Transfection
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Affiliation(s)
- S D Feighner
- Department of Metabolic Disorders, Department of Medicinal Chemistry, Merck Research Laboratories, Building RY-80Y-265, 126 East Lincoln Avenue, Rahway, NJ 07065, USA
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175
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Davidson AJ, Stephan FK. Plasma glucagon, glucose, insulin, and motilin in rats anticipating daily meals. Physiol Behav 1999; 66:309-15. [PMID: 10336159 DOI: 10.1016/s0031-9384(98)00308-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The circadian food entrainable oscillator (FEO) mediates an increase in activity preceding access to periodic meals. The FEO is anatomically independent of the suprachiasmatic nucleus (SCN), but its locus remains to be established. Whether the FEO is located in the central nervous system (CNS) or in the periphery, it seems reasonable to assume that there is a link of communication between the digestive system and the CNS because only nutritive meals entrain the FEO. Subdiaphragmatic vagotomy and visceral deafferentation with capsaicin do not eliminate food-anticipatory activity (FAA), indicating that a neural signal is not necessary. The present study investigates the hypothesis that humoral signals from the digestive system act upon the CNS to trigger or entrain FAA. Intact rats and rats with SCN lesions were entrained to daily meals and then sacrificed prior to FAA or during FAA, but before meal access. Average plasma concentrations of glucose and insulin were nearly identical in both groups. Plasma and duodenal mucosal motilin concentrations also were not different between the two times. Corticosterone was elevated during anticipation, but the difference was not statistically reliable. Glucagon concentration was decreased during FAA compared to concentration prior to FAA in both intact and SCN-lesioned subjects. This difference was not observed in control rats fasted for the same number of hours, but not previously entrained to a daily meal. Although the decrease in glucagon could be a signal that initiates FAA, a causal role remains to be established.
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Affiliation(s)
- A J Davidson
- Department of Psychology, Florida State University, Tallahassee 32306-1270, USA
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176
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Faghih R, Burnell-Curty C, Lartey PA, Petersen A, Klein LL, Bennani YL, Nellans HN. Synthesis of 8(R),9(R)-9-deoxo-4''-deoxy-6,9-epoxyerythromycin: potent motilides. Eur J Med Chem 1999. [DOI: 10.1016/s0223-5234(99)80059-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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177
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Clark MJ, Wright T, Bertrand PP, Bornstein JC, Jenkinson KM, Verlinden M, Furness JB. Erythromycin derivatives ABT 229 and GM 611 act on motilin receptors in the rabbit duodenum. Clin Exp Pharmacol Physiol 1999; 26:242-5. [PMID: 10081621 DOI: 10.1046/j.1440-1681.1999.03022.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. The present study was undertaken to determine whether the macrolide antibiotic erythromycin, its stable motilide derivatives ABT 229 and GM 611 and motilin act at the same receptors on intestinal muscle 2. Each compound contracted the longitudinal muscle of the rabbit duodenum in a concentration-dependent manner that was unaffected by 1 mumol/L tetrodotoxin. The potency order (pEC50 values in brackets) was motilin (8.4), ABT 229 (7.6), GM 611 (7.5) and erythromycin (6.0). 3. The motilin receptor antagonists GM 109 and [phe3, leu13]-motilin, both shifted the concentration-response curves for each agonist to the right, but did not affect concentration-response relationships for the muscarinic agonist carbachol. Schild regression analysis yielded similar pA2 values for GM 109 (in the range 7.2-7.5) for all agonists. This analysis was not done for [phe3, leu13]motilin, which was a non-competitive antagonist and partial agonist. 4. It is concluded that erythromycin, the motilides and motilin act at the same (motilin) receptor on rabbit duodenal muscle and do not have any detectable actions at other receptors in this preparation.
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Affiliation(s)
- M J Clark
- Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria, Australia
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178
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Sasaki N, Yoshihara T. The effect of motilin on the regulation mechanism of intestinal motility in conscious horses. J Vet Med Sci 1999; 61:167-70. [PMID: 10081757 DOI: 10.1292/jvms.61.167] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Laparotomy was performed on seven thoroughbreds to attach a force transducer to the proximal jejunum, distal jejunum, and ileum, as well as to the serous membrane of the cecum. Following observation of intestinal motility in conscious horses, they were intravenously injected with motilin (0.6 microgram/kg) to examine its effect on intestinal motility. Strong contractions peculiar to horses were observed in small intestine. Further, motilin caused strong contractions in the proximal jejunum. The results suggested the involvement of motilin in the regulation mechanism of intestinal motility.
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Affiliation(s)
- N Sasaki
- Equine Research Institute, Japan Racing Association, Tochigi, Japan
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179
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Furness JB, Clark MJ, Wright T, Bertrand PP, Bornstein JC, Verlinden M. An action of erythromycin in the intestine that is not mediated via motilin receptors. Clin Exp Pharmacol Physiol 1999; 26:100-4. [PMID: 10065328 DOI: 10.1046/j.1440-1681.1999.03002.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. Erythromycin lactobionate caused a concentration-dependent inhibition of nerve-mediated contractions of the longitudinal muscle of the guinea-pig ileum, with a threshold for effect of 10-30 mumol/L. The non-antibiotic derivative of erythromycin ABT-229 had a similar effect, but was approximately 10-fold less potent. At a greater concentration (1 mmol/L), erythromycin also depressed the direct contractile effect of 10 mumol/L carbachol on the muscle. 2. Human/porcine motilin (up to 100 mumol/L) did not reduce the nerve-mediated contractions, although it did contract the muscle (threshold 30 mumol/L). Antagonists of motilin receptors (phe3leu13motilin, up to 1 mumol/L, and GM-109, up to 3 mumol/L) did not reduce responses to erythromycin. 3. Erythromycin contracted the longitudinal muscle of the rabbit duodenum, with a threshold concentration of 0.1 mumol/L and ABT-229 contracted this tissue at a threshold concentration of 0.01 mumol/L. Effects of both agonists were antagonized by the motilin receptor antagonists phe3leu13motilin (0.3 mumol/L) and GM-109 (1 mumol/L). 4. It is concluded that the site(s) at which erythromycin acts in the guinea-pig ileum is not a motilin receptor and that ABT-229 is selective for the motilin receptor in comparison with non-motilin erythromycin sites and is unlikely to act at the latter site in therapeutic doses.
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Affiliation(s)
- J B Furness
- Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria, Australia.
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180
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Abstract
In humans as well as in other animal species, the ingestion of food provides the fundamental source of energy for various cellular activities. The intake of food and the ability of controlling the plasma levels of substrates for energy production involve complex mechanisms that ensure a constantly adequate supply of metabolites both in the fasting and in the fed state. A number of hormonal peptides released from the gastrointestinal (GI) tract in response to the ingestion of food have been shown to play a critical role in the postprandial control of glucose homeostasis. They are known to act through three main mechanisms of action. These include; (1) stimulation of insulin secretion of pancreatic islet (beta) cells; (2) inhibition of hepatic gluconeogenesis by suppression of glucagon secretion; and (3) inhibition of GI motility. While for some of these hormones all three mechanisms of action are utilized under physiological conditions, others preferentially use one or a combination of two mechanisms for lowering postprandial hyperglycemia. Although the term glucoincretins (or incretins, or insulinotropic hormones) etymologically only describes factors capable of inducing insulin secretion, it is more frequently used to identify a larger class of peptides that, rather than manifesting a specific mechanism of action (i.e., insulin secretion), share the ability of controlling glucose excursion in the fed state (with or without a direct insulinotropic effect). The latter more inclusive meaning, incretins, is used in this article. This review summarizes recent advances on synthesis, secretion, blood plasma patterns, and metabolism of some of the major GI regulatory peptides acting in the postprandial state.
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Affiliation(s)
- R Perfetti
- Division of Endocrinology and Metabolism, Room B-131, Department of Medicine, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA.
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181
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Abstract
The feeding-entrained circadian oscillator (FEO) organizes locomotor activity and other variables to anticipate daily timed meals. Whether the biological substrate for the FEO is in the central nervous system or in the periphery, there must be communication between the gut and the brain to result in a behavioral output. To investigate potential neural routes of communication, rats with suprachiasmatic lesions were given systemic capsaicin (total dose: 100 mg/kg, i.p.) to produce visceral deafferentation. Deafferentation was confirmed using the phenyl-p-benzoquinone stretch test and the corneal irritation test. A 3-h meal was made available at the same time each day while wheel running was recorded for several weeks. Results indicated that rats with capsaicin lesions were somewhat more active overall and during nonanticipation times, but the onset time and the amount of anticipatory wheel running did not differ from vehicle-treated controls. In addition, reentrainment following a phase delay of mealtime and the persistence of anticipatory activity during food deprivation were similar between the groups. Since capsaicin deafferentation and subdiaphragmatic vagotomy do not prevent food-anticipatory activity, it is likely that communication between the gut and the brain is accomplished via a humoral route.
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Affiliation(s)
- A J Davidson
- Department of Psychology, Florida State University, Tallahassee 32306-1270, USA
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182
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De Ponti F, Malagelada JR. Functional gut disorders: from motility to sensitivity disorders. A review of current and investigational drugs for their management. Pharmacol Ther 1998; 80:49-88. [PMID: 9804054 DOI: 10.1016/s0163-7258(98)00021-7] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Functional gut disorders include several clinical entities defined on the basis of symptom patterns (e.g., functional dyspepsia, irritable bowel syndrome, functional abdominal pain, functional abdominal bloating), for which there is no established pathophysiological mechanism. Because there is no well-defined pathophysiological target, treatment should be aimed at symptom improvement. Prokinetics and antispasmodics have been widely used in the treatment of functional gut disorders on the assumption that disordered motility is the underlying cause of symptoms, and symptom improvement is indeed achievable with these compounds in some, but not all, patients with features of hypo- or hypermotility, respectively. In the first part of this review, we cover the basic pharmacology and discuss the rationale for the clinical use of prokinetics and antispasmodics. On the other hand, in the past few years, the explosive growth in the research focusing on visceral sensitivity and visceral reflexes has suggested that at least some patients with functional gut disorders have altered visceral perception. Thus, the second part of the review covers these developments and focuses on studies addressing the issue of drugs modulating visceral sensitivity.
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Affiliation(s)
- F De Ponti
- Department of Internal Medicine and Therapeutics, University of Pavia, Italy
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183
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Momose K, Inui A, Asakawa A, Ueno N, Nakajima M, Kasuga M. Anxiolytic effect of motilin and reversal with GM-109, a motilin antagonist, in mice. Peptides 1998; 19:1739-42. [PMID: 9880080 DOI: 10.1016/s0196-9781(98)00131-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
There have been few reports on the effects of the brain-gut peptide motilin on the central nervous system (CNS). We administered motilin intracerebroventricularly to mice and investigated the effect of motilin on anxiety using an elevated plus-maze. Motilin produced a significant decrease in anxiety with an inverted U-shaped dose response. To determine whether the anxiolytic effect of motilin was mediated via motilin receptors in the brain, the effect of GM-109, a novel motilin receptor antagonist, was investigated. GM-109 showed a significant and dose-dependent antagonism on the motilin-induced anxiolytic effect. GM-109 administered alone had no effect on anxiety. These results suggest that motilin receptors are present in the brain and may have a role in anxiety and emotion.
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Affiliation(s)
- K Momose
- Second Department of Internal Medicine, Kobe University School of Medicine, Japan
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