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Abstract
Ghrelin and motilin are released from gastrointestinal endocrine cells during hunger, to act through G protein-coupled receptors that have closely related amino acid sequences. The actions of ghrelin are more complex than motilin because ghrelin also exists outside the GI tract, it is processed to des-acyl ghrelin which has activity, ghrelin can exist in truncated forms and retain activity, the ghrelin receptor can have constitutive activity and is subject to biased agonism and finally additional ghrelin-like and des-acyl ghrelin receptors are proposed. Both ghrelin and motilin can stimulate gastric emptying, acting via different pathways, perhaps influenced by biased agonism at the receptors, but research is revealing additional pathways of activity. For example, it is becoming apparent that reduction of nausea may be a key therapeutic target for ghrelin receptor agonists and perhaps for compounds that modulate the constitutive activity of the ghrelin receptor. Reduction of nausea may be the mechanism through which gastroparesis symptoms are reduced. Intriguingly, a potential ability of motilin to influence nausea is also becoming apparent. Ghrelin interacts with digestive function through its effects on appetite, and ghrelin antagonists may have a place in treating Prader-Willi syndrome. Unlike motilin, ghrelin receptor agonists also have the potential to treat constipation by acting at the lumbosacral defecation centres. In conclusion, agonists of both ghrelin and motilin receptors hold potential as treatments for specific subsets of digestive system disorders.
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Barshop K, Kuo B. The investigational drug camicinal for the treatment of gastroparesis. Expert Opin Investig Drugs 2014; 24:133-140. [DOI: 10.1517/13543784.2015.975792] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Camilleri M, Acosta A. A ghrelin agonist fails to show benefit in patients with diabetic gastroparesis: let's not throw the baby out with the bath water. Neurogastroenterol Motil 2013; 25:859-63. [PMID: 24001134 DOI: 10.1111/nmo.12226] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 08/08/2013] [Indexed: 02/08/2023]
Abstract
Ghrelin is the endogenous ligand for the growth hormone secretagogue-1a receptor and is a potential target for treatment of gastroparesis. This viewpoint assesses the potential role of ghrelin agonists in the treatment of gastroparesis through a review of the early phase, randomized, controlled trials of ghrelin agonists in patients with diabetes and, either, delayed gastric emptying at the time of the trial or symptoms at the time of the trial, and prior documentation of delayed gastric emptying of solids. Whereas recent experience with ghrelin agonists that have a macrocycle structure (TZP-101, TZP-102) has not confirmed earlier promising results, there is little evidence that ghrelin receptors downregulate with repeated treatment, in contrast to motilin receptors. Phase IIa clinical trials performed with a different agent (RM-131, which is a small molecule ghrelin agonist) suggest that, as a class, ghrelin agonists may be efficacious in stimulating gastric emptying. It is premature to dismiss ghrelin agonists as potential therapies for gastroparesis.
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Affiliation(s)
- M Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (CENTER), Mayo Clinic, Rochester, MN, USA
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Guo WJ, Yao SK, Zhang YL, Yan J, Yin LJ, Li3 HL. Relationship between Symptoms and Gastric Emptying of Solids in Functional Dyspepsia. J Int Med Res 2012. [PMID: 23206454 DOI: 10.1177/030006051204000511] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Objective: Functional dyspepsia is a heterogeneous disorder and different pathophysiological mechanisms underlie its symptom patterns. This study investigated the relationship between dyspepsia symptoms and overall and proximal gastric emptying in patients with functional dyspepsia. Methods: A total of 93 patients with functional dyspepsia and 32 healthy subjects were enrolled in this cross-sectional study. Prevalence and severity of eight dyspepsia symptoms were recorded. Gastric emptying was measured using single photon emission computed tomography scanning. Results: Overall and proximal gastric emptying were delayed in 47.3% (44/93) and 46.2% (43/93) of the patients, respectively. Logistic regression analyses showed that presence of nausea was associated with delayed proximal gastric emptying (odds ratio 4.951; 95% confidence interval 1.321, 18.558). There were no significant differences between normal and delayed overall gastric emptying according to presence of symptoms. Conclusions: Presence of nausea might indicate delayed gastric emptying of the proximal stomach. Promotion of proximal gastric emptying may constitute an effective therapy for patients with functional dyspepsia who report nausea as the dominant symptom.
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Affiliation(s)
- W-J Guo
- Graduate School, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
- Department of Gastroenterology and 3Department of Nuclear Medicine, China-Japan Friendship Hospital, Ministry of Health, Beijing, China
| | - S-K Yao
- Department of Gastroenterology and 3Department of Nuclear Medicine, China-Japan Friendship Hospital, Ministry of Health, Beijing, China
| | - Y-L Zhang
- Department of Gastroenterology and 3Department of Nuclear Medicine, China-Japan Friendship Hospital, Ministry of Health, Beijing, China
| | - J Yan
- Department of Gastroenterology and 3Department of Nuclear Medicine, China-Japan Friendship Hospital, Ministry of Health, Beijing, China
| | - L-J Yin
- Graduate School, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - H-L Li3
- Graduate School, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
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Sanger GJ. Motilin receptor neuropharmacology: revised understanding. Curr Opin Pharmacol 2012; 12:641-6. [PMID: 22858405 DOI: 10.1016/j.coph.2012.07.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/12/2012] [Accepted: 07/17/2012] [Indexed: 12/17/2022]
Abstract
Although motilin was identified >40 years ago as a gastrointestinal hormone capable of stimulating gastric emptying, the relatively recent availability of molecular tools and focus on its neuronal activities are now clarifying mechanisms of action. In rodents, only motilin receptor pseudogenes are identified. In human stomach, facilitation of enteric cholinergic activity is identified as the main mechanism by which gastric emptying is increased; some motilin agonists act in a prolonged manner, contrasting with motilin itself and with studies using recombinant receptors. As such, assays using recombinant receptors seem poor predictors of in vivo activity. High-throughput screening enabled selective motilin agonists to be identified, which together with enhanced understanding into neuromuscular actions of motilin, promises to deliver rational treatments of disorders with delayed gastric emptying.
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Affiliation(s)
- Gareth J Sanger
- Neurogastroenterology Group, Blizard Institute, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, United Kingdom.
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Does grading the severity of gastroparesis based on scintigraphic gastric emptying predict the treatment outcome of patients with gastroparesis? Dig Dis Sci 2011; 56:1147-53. [PMID: 21113801 DOI: 10.1007/s10620-010-1485-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Accepted: 11/04/2010] [Indexed: 12/25/2022]
Abstract
OBJECTIVES The objectives of this study were as follows: (1) Whether gastric emptying is different between gastroparesis (GP) patients responding or not responding to standard medical therapy; (2) Identifying if mild, moderate, and severe degrees of gastroparesis based on the scintigraphic gastric emptying test (GET) can predict treatment responses for GP of diabetic (DM) and idiopathic (ID) origin. METHODS A total of 165 patients (119 F) diagnosed with GP [126 (76%) DM, 39 (24%) ID etiology] failed medical treatment and required the gastric electrical stimulation (GES) device (GES group). In addition, 112 patients (89 F) [37 (33%) DM, 75 (67%) ID] with GP who symptomatically responded to medical therapies are the comparison group (MED GP). All patients underwent a standardized scintigraphic GET consisting of low-fat (2%) isotope labeled egg beaters meal of 250 kcal. We also analyzed the GET data to find cut-off points for different degrees of GP and identified mild (11-20% retention), moderate (21-35%), and severe gastroparesis (>35%) based on percent retention of isotope at 4 h. RESULTS Overall gastric retention at 4 h was significantly greater in the GES group (45±1.9%) than MED GP (30±2%) (p<0.001). The distribution severity of the GET was different in GES-treated patients than MED treated (p<0.001). In the diabetics, 57% of GES patients retained >35% after 4 h (severe) similar to 43% in the DM MED group. However, 50% of the ID GES patients had retention>35% at 4 h significantly more than only 17% of ID MED GP. Significantly more ID patients who responded to medical therapy had mild gastroparesis and significantly more requiring GES had severe GET (p<0.05). CONCLUSIONS (1) GET in patients whose GP symptoms were refractory to standard medical therapy and required GES was significantly slower than in GP patients whose symptoms responded to medical therapy. (2) Stratifying GET into mild, moderate, and severe degrees of gastric retention does not predict whether a medical or surgical approach will be better to control the symptoms of diabetic GP but does correlate with treatment for the idiopathic GP subgroup.
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Yin J, Chen J, Chen JDZ. Ameliorating effects and mechanisms of electroacupuncture on gastric dysrhythmia, delayed emptying, and impaired accommodation in diabetic rats. Am J Physiol Gastrointest Liver Physiol 2010; 298:G563-70. [PMID: 20093561 DOI: 10.1152/ajpgi.00252.2009] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The aim of this study was to investigate the effects and mechanisms of electroacupuncture (EA) on gastric accommodation, gastric dysrhythmia, and gastric emptying (GE) in streptozotocin (STZ)-induced diabetic rats. Five experiments were performed in five groups of STZ-induced diabetic rats to study the effects of EA at ST-36 (Zusanli) on gastric slow-wave dysrhythmia, delayed GE and intestinal transit, impaired gastric accommodation, and the mechanisms of EA involving the autonomic and opioidergic pathways. We found the following: 1) EA improved gastric dysrhythmia in the diabetic rats. The normal percentage of slow waves was 55.4 +/- 2.9% at baseline and significantly increased to 69.2 +/- 2.2% with EA (P = 0.01); this effect was blocked by naloxone. 2) EA resulted in a 21.4% increase in GE and 18.2% increase in small intestinal transit in the diabetic rats. 3) EA restored diabetes-induced impairment in gastric accommodation. Gastric accommodation was 0.98 +/- 0.13 ml with sham EA and significantly increased to 1.21 +/- 0.15 ml with EA (P = 0.01), and this effect was blocked by naloxone. 4) EA increased vagal activity assessed by the spectral analysis of the heart rate variability. We concluded that EA at ST-36 improves gastric dysrhythmia, delayed GE and intestinal transit, and impaired accommodation in STZ-induced diabetic rats, and the improvement seems to be mainly mediated via the vagal pathway. EA may have a promising therapeutic potential for diabetic gastroparesis.
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Affiliation(s)
- Jieyun Yin
- Division of Gastroenterology, University of Texas Medical Branch, Galveston, Texas, USA
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8
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sanger GJ, westaway SM, barnes AA, macpherson DT, muir AI, jarvie EM, bolton VN, cellek S, näslund E, hellström PM, borman RA, unsworth WP, matthews KL, lee K. GSK962040: a small molecule, selective motilin receptor agonist, effective as a stimulant of human and rabbit gastrointestinal motility. Neurogastroenterol Motil 2009. [DOI: 10.1111/j.1365-2982.2009.01270.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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9
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Zuo XL, Li YQ, Yang XZ, Guo M, Guo YT, Lu XF, Li JM, Desmond PV. Plasma and gastric mucosal 5-hydroxytryptamine concentrations following cold water intake in patients with diarrhea-predominant irritable bowel syndrome. J Gastroenterol Hepatol 2007; 22:2330-7. [PMID: 18265445 DOI: 10.1111/j.1440-1746.2006.04772.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND AND AIM The purpose of the present paper was to investigate the effects of cold water intake on 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindole acetic acid (5-HIAA) in diarrhea-predominant irritable bowel syndrome (d-IBS) patients, and to observe the relationship between 5-HT and symptomatology. METHODS The plasma 5-HT/5-HIAA concentrations at 0, 30 min, 60 min, 90 min, 120 min, 150 min and 180 min following cold or warm water intake were investigated in 32 female subjects with d-IBS and 21 healthy female subjects. Gastric mucosal 5-HT under fasting conditions and following water intake were further investigated in 15 d-IBS patients and nine healthy subjects. Symptomatology was assessed throughout the study. RESULTS The plasma 5-HT concentrations in IBS patients were significantly higher than those of controls at 30 min (P = 0.022), 60 min (P < 0.001), 90 min (P < 0.001), 120 min (P < 0.001) and 150 min (P = 0.001) after cold water intake. The peak plasma 5-HT/5-HIAA and area under the curve for 5-HT/5-HIAA were also higher in d-IBS patients (P < 0.001). Gastric mucosal 5-HT in d-IBS patients and controls did not show any significant differences both under fasting condition (P = 0.596) and after cold water intake (P = 0.426). Last, the d-IBS patients with symptoms had higher 5-HT concentration (P < 0.001) and there was a positive correlation (r = 0.714, P = 0.001)between the symptomatology and plasma 5-HT level. CONCLUSIONS These data suggest that symptomatology following cold water intake may be associated with increased plasma 5-HT concentrations in female subjects with d-IBS.
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Affiliation(s)
- Xiu Li Zuo
- Department of Gastroenterology, Qilu Hospital, Shandong University, Jinan, China
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McCallum RW, Cynshi O. Clinical trial: effect of mitemcinal (a motilin agonist) on gastric emptying in patients with gastroparesis - a randomized, multicentre, placebo-controlled study. Aliment Pharmacol Ther 2007; 26:1121-30. [PMID: 17894654 DOI: 10.1111/j.1365-2036.2007.03461.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Mitemcinal is an orally active motilin agonist that could potentially improve gastric emptying. AIM To investigate the effect of mitemcinal on gastric emptying in patients with idiopathic and diabetic gastroparesis. METHODS In a randomized, double-blind design, 106 patients were randomized into four dosing regimens (22 to placebo and 21 each to mitemcinal 10 mg, 20 mg, 30 mg bid or 20 mg tid) for 28 days. A standardized scintigraphic gastric emptying test was performed at screening and again after completing the 4-week protocol. RESULTS All doses of mitemcinal showed prokinetic activity. A significant improvement in meal retention at 240 min was noted even in the lowest dose group with the greatest improvement observed with 30 mg bid group (75% vs. 10% in placebo group). Diabetic patients responded better than the idiopathic subgroup. In diabetic patients, blood glucose at 1 h after a meal showed dose-dependent elevation. Although gastroparetic symptoms improved with both mitemcinal and placebo, the prominent placebo effect was not statistically exceeded by mitemcinal. Baseline scintigraphy results exhibited no clear correlation between the severity of gastroparetic symptoms and the status of gastric emptying. CONCLUSION Mitemcinal is capable of accelerating gastric emptying in both diabetic and idiopathic patients with gastroparesis.
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Affiliation(s)
- R W McCallum
- Center for GI Nerve and Muscle Function, University of Kansas Medical Center, Kansas City, KS, USA
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11
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Karamanolis G, Caenepeel P, Arts J, Tack J. Determinants of symptom pattern in idiopathic severely delayed gastric emptying: gastric emptying rate or proximal stomach dysfunction? Gut 2007; 56:29-36. [PMID: 16840507 PMCID: PMC1856678 DOI: 10.1136/gut.2005.089508] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Revised: 06/03/2006] [Accepted: 06/12/2006] [Indexed: 12/22/2022]
Abstract
BACKGROUND Idiopathic gastroparesis is a syndrome characterised by severely delayed gastric emptying of solids without an obvious underlying organic cause. Although delayed gastric emptying is traditionally considered the mechanism underlying the symptoms in these patients, poor correlations with symptom severity have been reported. AIMS To investigate proximal stomach function and to study the correlation of delayed gastric emptying and proximal stomach dysfunction with symptom pattern and severity in idiopathic gastroparesis. METHODS 58 consecutive patients (19 men, mean (standard deviation) age 41 (2) years) with severely delayed solid gastric emptying (gastric half-emptying time (t(1/2))>109 min) without an organic cause were recruited. They filled out a symptom-severity questionnaire and underwent a gastric barostat study for assessment of gastric sensitivity and accommodation. Correlation of these mechanisms with symptom pattern and overall symptom severity (sum of individual symptoms) was analysed. RESULTS At two different cut-off levels for gastric emptying (upper limit of normal t(1/2) up to 1.5 and 2 times), no significant change in symptom pattern occurred. 25 (43%) patients had impaired accommodation, and this was associated with higher prevalence of early satiety (p<0.005) and weight loss (p = 0.009). 17 (29%) patients had hypersensitivity to gastric distension, and this was associated with higher prevalences of epigastric pain (p = 0.005), early satiety (p = 0.04) and weight loss (p<0.005). Overall symptom severity was not correlated with gastric emptying or accommodation, but only with sensitivity to gastric distension (R = -0.3898, p = 0.003) and body weight (R = -0.4233, p = 0.001). CONCLUSIONS In patients with idiopathic gastroparesis, the symptom pattern is determined by proximal stomach dysfunction rather than by the severity of delayed emptying.
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Affiliation(s)
- G Karamanolis
- Center for Gastroenterological Research, KU Leuven, Belgium
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12
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Tack J, Coulie B, Verbeke K, Janssens J. Influence of delaying gastric emptying on meal-related symptoms in healthy subjects. Aliment Pharmacol Ther 2006; 24:1045-50. [PMID: 16984498 DOI: 10.1111/j.1365-2036.2006.03095.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Although delayed gastric emptying is often found in functional dyspepsia, a causal role for delayed emptying in inducing symptoms has not been demonstrated. AIM To investigate the influence of delaying gastric emptying rate in healthy volunteers on the occurrence of meal-related symptoms. METHODS Fourteen healthy subjects (six men, mean age 23 +/- 1) underwent gastric emptying studies twice using the 14C octanoic acid and 13C glycin breath test after pre-treatment with saline or sumatriptan 6 mg s.c. Breath samples were taken before meal and at 15-min intervals for a period of 360 min postprandially. At each breath sampling, the subject was asked to grade the intensity (0-6) of four dyspeptic symptoms. RESULTS Sumatriptan pre-treatment significantly delayed solid but not liquid gastric emptying (t1/2 respectively 159 +/- 11 vs. 112 +/- 9 min, P < 0.005 and 134 +/- 11 vs. 116 +/- 12 min, N.S.). Sumatriptan significantly decreased the mean cumulative symptom score (21.3 +/- 5.5 vs. 8.0 +/- 2.6, P = 0.01), as well as scores for each individual symptom. CONCLUSION A moderate delay in gastric emptying in health is not associated with an increase of meal-related symptoms. This observation argues against a causal role for delayed gastric emptying in the pathogenesis of dyspeptic symptoms.
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Affiliation(s)
- J Tack
- Department of Gastroenterology, University Hospitals Leuven, Leuven, Belgium.
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Ma B, Wynn G, Dunn PM, Burnstock G. Increased 5-HT(3)-mediated signalling in pelvic afferent neurons from mice deficient in P2X(2) and/or P2X (3) receptor subunits. Purinergic Signal 2006; 2:481-9. [PMID: 18404485 PMCID: PMC2096651 DOI: 10.1007/s11302-006-9017-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Accepted: 10/25/2005] [Indexed: 01/18/2023] Open
Abstract
Extracellular ATP and 5-hydroxytryptamine (5-HT) are both involved in visceral sensory pathways by interacting with P2X and 5-HT3 receptors, respectively. We have investigated the changes in P2X and 5-HT3-mediated signalling in pelvic afferent neurons in mice deficient in P2X2 and/or P2X3 subunits by whole-cell recording of L6–S2 dorsal root ganglion (DRG) neurons and by multi-unit recording of pelvic afferents of the colorectum. In wildtype DRG neurons, ATP evoked transient, sustained or mixed (biphasic) inward currents. Transient currents were absent in P2X3−/− neurons, whereas sustained currents were absent in P2X2−/− DRG neurons. Neither transient nor sustained currents were observed following application of ATP or α,β-methylene ATP (α,β-meATP) in P2X2/P2X3Dbl−/− DRG neurons. 5-HT was found to induce a fast inward current in 63% of DRG neurons from wildtype mice, which was blocked by tropisetron, a 5-HT3 receptor antagonist. The percentage of DRG neurons responding to 5-HT was significantly increased in P2X 2−/−, P2X3−/− and P2X2/P2X3Dbl−/− mice, and the amplitude of 5-HT response was significantly increased in P2X2/P2X3Dbl−/− mice. The pelvic afferent response to colorectal distension was attenuated in P2X2/P2X3Dbl−/− mice, but the response to serosal application of 5-HT was enhanced. Furthermore, tropisetron resulted in a greater reduction in pelvic afferent responses to colorectal distension in the P2X2/P2X3Dbl−/− preparations. These data suggest that P2X receptors containing the P2X2 and/or P2X3 subunits mediate purinergic activation of colorectal afferents and that 5-HT signalling in pelvic afferent neurons is up-regulated in mice lacking P2X2 or P2X3 receptor genes. This effect is more pronounced when both subunits are absent.
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Affiliation(s)
- Bei Ma
- Autonomic Neuroscience Centre, Royal Free and University College Medical School, Rowland Hill Street, London, NW3 2PF, UK
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Abstract
Recent research has provided new information about drugs that could be used to treat functional motility disorders. Promotility drugs accelerate gastric emptying or colonic transit and these properties may contribute to their efficacy in treating symptoms associated with gastroparesis, functional dyspepsia or constipation. 5-Hydroxytryptamine4 receptors are targets for drugs (tegaserod, renzapride) that treat symptoms in constipated irritable bowel syndrome patients and in gastroparesis. Drugs acting at motilin (erythromycin) and cholecystokinin-1 (dexloxiglumide) receptors accelerate gastric emptying. Dexloxiglumide might be useful in the treatment of functional dyspepsia particularly that associated with lipid intake. Alvimopan is a mu-opioid receptor antagonist that does not cross the blood brain barrier. Alvimopan is effective in treating postsurgical ileus and perhaps opiate-induced bowel dysfunction. Successes and failures of recent efforts to develop promotility agents revealed opportunities and challenges for developing new promotility drugs. The pharmacological properties of partial agonists might be exploited to develop effective promotility drugs. However, opposing actions of promotility agents on motility (increased contraction vs decreased accommodation) limit the clinical efficacy of drugs with these opposing actions. Selection of appropriate patient populations for evaluation of new drugs is also critical.
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Affiliation(s)
- J J Galligan
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA.
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Thielemans L, Depoortere I, Perret J, Robberecht P, Liu Y, Thijs T, Carreras C, Burgeon E, Peeters TL. Desensitization of the Human Motilin Receptor by Motilides. J Pharmacol Exp Ther 2005; 313:1397-405. [PMID: 15764739 DOI: 10.1124/jpet.104.081497] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tachyphylaxis may have contributed to the failure of the motilide ABT-229 [N-ethyl, N-methyl 4'' deoxy erythromycin (EM)-B enolether] in clinical trials. We compared the desensitizing potency of structurally related motilides [EM-A, EM-A enolether (ME4), N-ethyl, N-methyl EM-A (ME36), EM-B enolether (ME67), N-ethyl, N-methyl EM-A enolether (EM523), ABT-229 and 4'' deoxy EM-A enolether (KOS1326)] in a Chinese hamster ovary (CHO)-K1 cell line expressing the human motilin receptor (MTLR) and in rabbit duodenal segments. CHO-MTLR cells were preincubated with motilides prior to stimulation with motilin. The negative logarithm of the preincubation concentration reducing the maximal motilin-induced Ca(2+) flux to 50% was calculated (pDC(50)). Internalization was visualized in CHO-K1 cells containing an enhanced green fluorescent protein (EGFP)-tagged MTLR and quantified in binding experiments. The contractile response of repeated stimulations was measured in duodenal segments. In CHO-MTLR cells, the pDC(50) was ABT-229 (8.78) > motilin (7.77) > EM-A (4.78), different from their order of potency to induce Ca(2+) release (pEC(50)): motilin (9.39) > ABT-229 (8.46) > EM-A (7.11). In cells with the EGFP-tagged MTLR, ABT-229 decreased membrane fluorescence by 25 +/- 2% compared with 16 +/- 2% for motilin and 8 +/- 2% for EM-A. Binding studies confirmed that EM-A did not induce MTLR internalization (residual binding 96 +/- 4% compared with motilin, 31 +/- 3% and ABT-229, 21 +/- 1%). Comparison of the pDC(50) and pEC(50) values of the other motilides ME4 (5.90; 8.08), ME67 (6.03; 8.12), ME36 (3.32; 6.62), EM-523 (6.02; 8.22), and KOS1326 (7.32; 8.14) suggested that the strong desensitizing properties of ABT-229 are mostly related to the removal of the 4''-OH of the cladinose sugar. The decline of the contractile response in duodenal segments correlated with the pDC(50). The ability to desensitize and internalize the MTLR is not only determined by potency. This may be an important criterion for the development of a clinically useful compound.
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Affiliation(s)
- Leen Thielemans
- Gut Hormone Lab, Center for Gastroenterological Research, Department of Pathophysiology, Katholieke Universiteit Leuven, Belgium
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Nam JH, Alnoah Z, Yenumula SR, Murthy S. Epidemiology, pathogenesis and treatment of irritable bowel syndrome. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.13.8.1213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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17
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Dhir R, Richter JE. Erythromycin in the short- and long-term control of dyspepsia symptoms in patients with gastroparesis. J Clin Gastroenterol 2004; 38:237-42. [PMID: 15128069 DOI: 10.1097/00004836-200403000-00008] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Few prokinetic drugs are available to treat gastroparesis. Data are limited on short-term and long-term efficacy of erythromycin as a prokinetic drug. GOALS Assess efficacy of low-dose erythromycin suspension to treat gastroparesis. STUDY Patients with dyspepsia and gastroparesis by gastric emptying study were treated with low-bulk diet and low-dose (50-100 mg 3 times a day and at bedtime) oral erythromycin suspension. Data were collected by retrospective chart review and telephone questionnaire for short- and long-term follow-up, respectively. RESULTS Of 25 patients, 18 had short-term follow-up, 18 had longterm follow-up, and 14 had both. On short-term follow-up, 15 patients (83%) experienced some or dramatic improvement, while 3 (17%) experienced worsening or no change in symptoms (P = 0.005). Mean duration of long-term use was 11 +/- 7 months. On long-term followup, 12 (67%) patients noticed some or dramatic improvement, while 6 (33%) experienced worsening or no change in symptoms (P = 0.16). Correlation (0.7) between short- and long-term response was significant (P < 0.005). Of the 3 patients with poor short-term response, none did well long term. Of the 11 patients with some or dramatic response in short-term, 7 continued to have some response long term. There was no relation between gastric emptying time and response to erythromycin suspension. CONCLUSIONS Treatment of gastroparesis with low-dose erythromycin and low-bulk diet results in a dramatic short-term improvement in the majority of patients. Short-term response predicts long-term response. This response may not be as great, possibly due to tachyphylaxis.
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Affiliation(s)
- Rohtashav Dhir
- Department of Gastroenterology and Hepatology, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
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Drewes AM, Gregersen H, Arendt-Nielsen L. Experimental pain in gastroenterology: a reappraisal of human studies. Scand J Gastroenterol 2003; 38:1115-30. [PMID: 14686714 DOI: 10.1080/00365520310004399] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- A M Drewes
- Center for Visceral Biomechanics and Pain, Dept. of Medical Gastroenterology, Aalborg University Hospital, Denmark.
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19
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Abstract
Colonic motility disorders are common conditions. However, our understanding of normal, and, consequently, pathological motor function of the colon remains limited, mainly due to the relative inaccessibility of this organ for study. Investigation of colonic motility may encompass one or more of the four separate components (myoelectric activity, phasic and tonic contractile activity and movement of intraluminal content) using electrophysiological, manometric or transit studies. Although transit studies provide the best 'functional' appreciation of colonic motor activity, and are the only techniques used in contemporary clinical practice, manometric methods are becoming increasingly popular, as they allow a direct study of colonic contractile activity over prolonged periods. To date, the majority of studies have been limited to the pelvic colon by a retrograde (per rectal) approach; however, recent technological advances have facilitated 'pan-colonic' investigation. This review concentrates on manometry of the human colon proximal to the sigmoid, and includes evaluation of both phasic and tonic motor activity, by utilization of perfused-tube and solid-state manometric catheters, and also the electronic barostat. Methodological techniques, experimental protocols and the analysis and interpretation of recorded data are critically explored, and a contemporary classification of colonic contractile activities is presented.
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Affiliation(s)
- S M Scott
- Academic Department of Surgery, GI Physiology Unit, Barts and the London, Queen Mary School of Medicine & Dentistry, The Royal London Hospital, Whitechapel, London, UK.
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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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