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Sanger GJ, Wang Y, Hobson A, Broad J. Motilin: towards a new understanding of the gastrointestinal neuropharmacology and therapeutic use of motilin receptor agonists. Br J Pharmacol 2013; 170:1323-32. [PMID: 23189978 PMCID: PMC3838679 DOI: 10.1111/bph.12075] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 10/26/2012] [Accepted: 11/15/2012] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED The gastrointestinal hormone motilin has been known about for >40 years, but after identification of its receptor and subsequent development of new tools and methods, a reappraisal of its actions is required. Firstly, it is important to note that motilin and ghrelin receptors are members of the same family (similar genomic organization, gastrointestinal distribution and abilities to stimulate gastrointestinal motility), yet each fails to recognize the ligand of the other; and whereas ghrelin and ghrelin receptors are widespread outside the gastrointestinal tract, motilin and its receptors are largely restricted to the gastrointestinal tract. Secondly, although some studies suggest motilin has activity in rodents, most do not, and receptor pseudogenes exist in rodents. Thirdly, motilin preferentially operates by facilitating enteric cholinergic activity rather than directly contracting the muscle, despite the relatively high expression of receptor immunoreactivity in muscle. This activity is ligand-dependent, with short-lasting actions of motilin contrasting with longer-lasting actions of the non-selective and selective motilin receptor agonists erythromycin and GSK962040. Finally, the use of erythromycin (also an antibiotic drug) to treat patients requiring acceleration of gastric emptying has led to concerns over safety and potential exacerbation of antibiotic resistance. Replacement motilin receptor agonists derived from erythromycin (motilides) have been unsuccessful. New, non-motilide, small molecule receptor agonists, designed to minimize self-desensitization, are now entering clinical trials for treating patients undergoing enteral feeding or with diabetic gastroparesis. Thus, for the translational pharmacologist, the study of motilin illustrates the need to avoid overreliance on artificial systems, on structural information and on animal studies. LINKED ARTICLES This article is part of a themed section on Neuropeptides. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.170.issue-7.
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Affiliation(s)
- G J Sanger
- Neurogastroenterology Group, Blizard Institute, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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Cheon GJ, Cui Y, Yeon DS, Kwon SC, Park BG. Mechanisms of motility change on trinitrobenzenesulfonic Acid-induced colonic inflammation in mice. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2012; 16:437-46. [PMID: 23269907 PMCID: PMC3526749 DOI: 10.4196/kjpp.2012.16.6.437] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 10/17/2012] [Accepted: 10/31/2012] [Indexed: 01/02/2023]
Abstract
Ulcerative colitis is an inflammatory bowel disease (IBD) characterized by recurrent episodes of colonic inflammation and tissue degeneration in human or animal models. The contractile force generated by the smooth muscle is significantly attenuated, resulting in altered motility leading to diarrhea or constipation in IBD. The aim of this study is to clarify the altered contractility of circular and longitudinal smooth muscle layers in proximal colon of trinitrobenzen sulfonic acid (TNBS)-induced colitis mouse. Colitis was induced by direct injection of TNBS (120 mg/kg, 50% ethanol) in proximal colon of ICR mouse using a 30 G needle anesthetized with ketamin (50 mg/kg), whereas animals in the control group were injected of 50% ethanol alone. In TNBS-induced colitis, the wall of the proximal colon is diffusely thickened with loss of haustration, and showed mucosal and mucular edema with inflammatory infiltration. The colonic inflammation is significantly induced the reduction of colonic contractile activity including spontaneous contractile activity, depolarization-induced contractility, and muscarinic acetylcholine receptor-mediated contractile response in circular muscle layer compared to the longitudinal muscle layer. The inward rectification of currents, especially, important to Ca(2+) and Na(+) influx-induced depolarization and contraction, was markedly reduced in the TNBS-induced colitis compared to the control. The muscarinic acetylcholine-mediated contractile responses were significantly attenuated in the circular and longitudinal smooth muscle strips induced by the reduction of membrane expression of canonical transient receptor potential (TRPC) channel isoforms from the proximal colon of the TNBS-induced colitis mouse than the control.
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Affiliation(s)
- Gab Jin Cheon
- Department of Gastroenterology, Gangneung Asan Medical Center, Gangneung 210-701, Korea
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Bajka BH, Clarke JM, Topping DL, Cobiac L, Abeywardena MY, Patten GS. Butyrylated starch increases large bowel butyrate levels and lowers colonic smooth muscle contractility in rats. Nutr Res 2010; 30:427-34. [PMID: 20650351 DOI: 10.1016/j.nutres.2010.06.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 06/06/2010] [Accepted: 06/07/2010] [Indexed: 11/28/2022]
Abstract
The short-chain fatty acids acetate, propionate, and butyrate are produced by colonic bacterial fermentation of carbohydrates. Butyrate is important in the regulation of the colonocyte cell cycle and gut motility and may also reduce the risk of large bowel cancer. We have shown that dietary butyrylated starch can deliver butyrate to the large bowel in a sustained manner. We hypothesized that ingestion of butyrylated starch increases large bowel butyrate levels and decreases colonic contractility. Groups of male Sprague-Dawley rats (n = 8) were fed AIN-93G-based diet containing a highly digestible low-amylose maize starch (LAMS) control or 5% or 10% butyrylated LAMS (LAMSB) for 10 days. We found that cecal but not colonic tissue weight as well as cecal and distal colonic digesta weights and fecal output were higher in LAMSB fed rats. Butyrylated LAMS lowered digesta pH throughout the large bowel. Cecal, proximal, and distal colonic butyrate pools and portal venous butyrate concentrations were higher in rats fed LAMSB. Electrically stimulated and receptor-dependent carbachol and prostaglandin E(2)-induced isotonic contractions were lower in isolated intact sections of proximal colon (P < .05) but not the terminal ileum after 10% LAMSB ingestion. These results demonstrated that elevation of butyrate levels in the large bowel of the rat correlated with reduction of contractile activity of the colonic musculature, which may assist in the reabsorption of water and minerals.
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Affiliation(s)
- Balazs H Bajka
- CSIRO Preventative Health National Research Flagship, Food and Nutritional Sciences, Adelaide, South Australia 5000, Australia
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Depoortere I, Thijs T, Janssen S, De Smet B, Tack J. Colitis affects the smooth muscle and neural response to motilin in the rabbit antrum. Br J Pharmacol 2009; 159:384-93. [PMID: 20002099 DOI: 10.1111/j.1476-5381.2009.00537.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND AND PURPOSE The underlying mechanisms of gastric dysfunction during or after an episode of intestinal inflammation are poorly understood. This study investigated the effects of colitis on the contractile effects of motilin, an important endocrine regulator of gastric motility, in the antrum. EXPERIMENTAL APPROACH Myeloperoxidase (MPO) activity, NF-kappaB activity and motilin receptor density were determined in the antrum of rabbits 5 days after the induction of 2,4,6-trinitrobenzenesulphonic acid colitis. Smooth muscle and neural responses to motilin were studied in antral smooth muscle strips in vitro. KEY RESULTS Colitis did not affect MPO activity, but increased NF-kappaB activity in the antrum. Motilin receptor density in the antrum was not affected. Under control conditions, motilin induced a slowly developing tonic smooth muscle contraction. Five days post-inflammation, tonic contractions to motilin were reduced and preceded by a rapid initial contraction. Other kinases were recruited for the phosphorylation of myosin light chain (MLC) (a multi-functional MLC kinase), and for the inhibition of MLC phosphatase (Rho kinase in addition to protein kinase C) to mediate the motilin-induced contractions during inflammation. Colitis potentiated the cholinergic neural on-contractions in the antrum. This was associated with a hyper-reactivity to motilin and an increased muscle response to ACh. CONCLUSIONS AND IMPLICATIONS Colitis altered the course of the motilin-induced smooth muscle contraction in the antrum. This involved changes in the kinases phosphorylating MLC. Increased cholinergic excitability to motilin in the antrum may play a role in the pathogenesis of inflammation-associated gastric motility disorders.
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Affiliation(s)
- Inge Depoortere
- Centre for Gastroenterological Research, Catholic University of Leuven, Leuven, Belgium.
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Constitutive basal and stimulated human small bowel contractility is enhanced in obesity. ANNALS OF SURGICAL INNOVATION AND RESEARCH 2009; 3:4. [PMID: 19379492 PMCID: PMC2673225 DOI: 10.1186/1750-1164-3-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Accepted: 04/20/2009] [Indexed: 11/10/2022]
Abstract
Small bowel contractility may be more prominent in obese subjects, such that there is enhanced nutrient absorption and hunger stimulation. However, there is little evidence to support this. This study examined in vitro small bowel contractility in obese patients versus non-obese patients. Samples of histologically normal small bowel were obtained at laparoscopic Roux-en-Y gastric bypass from obese patients. Control specimens were taken from non-obese patients undergoing small bowel resection for benign disease or formation of an ileal pouch-anal anastamosis. Samples were transported in a pre-oxygenated Krebs solution. Microdissected circular smooth muscle strips were suspended under 1 g of tension in organ baths containing Krebs solution oxygenated with 95% O2/5% CO2 at 37°C. Contractile activity was recorded using isometric transducers at baseline and in response to receptor-mediated contractility using prostaglandin F2a, a nitric oxide donor and substance P under both equivocal and non-adreneregic, non-cholinergic conditions (guanethidine and atropine). Following equilibration, the initial response to the cholinergic agonist carbachol (0.1 mmol/L) was significantly increased in the obese group (n = 63) versus the lean group (n = 61) with a mean maximum response: weight ratio of 4.58 ± 0.89 vs 3.53 ± 0.74; (p = 0.032). Following washout and re-calibration, cumulative application of substance P and prostaglandin F2a produced concentration-dependent contractions of human small bowel smooth muscle strips. Contractile responses of obese small bowel under equivocal conditions were significantly increased compared with non-obese small bowel (p < 0.05 for all agonists). However, no significant differences were shown between the groups when the experiments were performed under NANC conditions. There were no significant differences found between the groups when challenged with nitric oxide, under either equivocal or NANC conditions. Stimulated human small bowel contractility is increased in obese patients suggesting faster enteric emptying and more rapid intestinal transit. This may translate into enhanced appetite and reduced satiety.
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Hirota CL, McKay DM. Loss of Ca-mediated ion transport during colitis correlates with reduced ion transport responses to a Ca-activated K channel opener. Br J Pharmacol 2009; 156:1085-97. [PMID: 19298254 DOI: 10.1111/j.1476-5381.2009.00122.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND AND PURPOSE Epithelial surface hydration is critical for proper gut function. However, colonic tissues from individuals with inflammatory bowel disease or animals with colitis are hyporesponsive to Cl(-) secretagogues. The Cl(-) secretory responses to the muscarinic receptor agonist bethanechol are virtually absent in colons of mice with dextran sodium sulphate (DSS)-induced colitis. Our aim was to define the mechanism underlying this cholinergic hyporesponsiveness. EXPERIMENTAL APPROACH Colitis was induced by 4% DSS water, given orally. Epithelial ion transport was measured in Ussing chambers. Colonic crypts were isolated and processed for mRNA expression via RT-PCR and protein expression via immunoblotting and immunolocalization. KEY RESULTS Expression of muscarinic M(3) receptors in colonic epithelium was not decreased during colitis. Short-circuit current (I(SC)) responses to other Ca(2+)-dependent secretagogues (histamine, thapsigargin, cyclopiazonic acid and calcium ionophore) were either absent or severely attenuated in colonic tissue from DSS-treated mice. mRNA levels of several ion transport molecules (a Ca(2+)-regulated Cl(-) channel, the intermediate-conductance Ca(2+)-activated K(+) channel, the cystic fibrosis transmembrane conductance regulator, the Na(+)/K(+)-ATPase pump or the Na(+)/K(+)/2Cl(-) co-transporter) were not reduced in colonic crypts from DSS-treated mice. However, protein expression of Na(+)/K(+)-ATPase alpha1 subunits was decreased twofold during colitis. Activation of Ca(2+)-activated K(+) channels increased I(SC) significantly less in DSS colons compared with control, as did the protein kinase C activator, phorbol 12-myristate 13-acetate. CONCLUSIONS AND IMPLICATIONS Decreased Na(+)/K(+)-ATPase expression probably contributes to overall epithelial hyporesponsiveness during colitis, while dysfunctional K(+) channels may account, at least partially, for lack of epithelial secretory responses to Ca(2+)-mediated secretagogues.
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Affiliation(s)
- Christina L Hirota
- Intestinal Disease Research Programme, Department of Pathology and Molecular Medicine, McMaster University, 3330 Hospital Drive Northwest, Calgary, Alberta, Canada.
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Soares PMG, Mota JMSC, Gomes AS, Oliveira RB, Assreuy AMS, Brito GAC, Santos AA, Ribeiro RA, Souza MHLP. Gastrointestinal dysmotility in 5-fluorouracil-induced intestinal mucositis outlasts inflammatory process resolution. Cancer Chemother Pharmacol 2008; 63:91-8. [PMID: 18324404 DOI: 10.1007/s00280-008-0715-9] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Accepted: 02/17/2008] [Indexed: 12/22/2022]
Abstract
AIM To evaluate gastrointestinal motility during 5-fluorouracil (5-FU)-induced intestinal mucositis. MATERIALS AND METHODS Wistar rats received 5-FU (150 mg kg(-1), i.p.) or saline. After the 1st, 3rd, 5th, 15th and 30th day, sections of duodenum, jejunum and ileum were removed for assessment of epithelial damage, apoptotic and mitotic indexes, MPO activity and GSH concentration. In order to study gastrointestinal motility, on the 3rd or 15th day after 5-FU treatment, gastric emptying in vivo was measured by scintilographic method, and stomach or duodenal smooth muscle contractions induced by CCh were evaluated in vitro. RESULTS On the third day of treatment, 5-FU induced a significant villi shortening, an increase in crypt depth and intestinal MPO activity and a decrease in villus/crypt ratio and GSH concentration. On the first day after 5-FU there was an increase in the apoptosis index and a decrease in the mitosis index in all intestinal segments. After the 15th day of 5-FU treatment, a complete reversion of all these parameters was observed. There was a delay in gastric emptying in vivo and a significant increase in gastric fundus and duodenum smooth muscle contraction, after both the 3rd and 15th day. CONCLUSION 5-FU-induced gastrointestinal dysmotility outlasts intestinal mucositis.
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Affiliation(s)
- Pedro M G Soares
- Centro de Biomedicina, Faculdade de Medicina, Universidade Federal do Ceará, Rodolfo Teófilo, Fortaleza, Brazil
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Akiho H, Khan WI, Al-Kaabi A, Blennerhassett P, Deng Y, Collins SM. Cytokine modulation of muscarinic receptors in the murine intestine. Am J Physiol Gastrointest Liver Physiol 2007; 293:G250-5. [PMID: 17431212 DOI: 10.1152/ajpgi.00545.2006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The extent to which gut motility and smooth muscle contractility are altered by intestinal inflammation depends on the nature of the underlying immune activation. The muscarinic receptor on smooth muscle plays a critical role in mediating acetylcholine-driven motor function. We examined the ability of cytokines to influence muscarinic receptor characteristics on intestinal longitudinal muscle and related the findings to studies on carbachol-induced contraction. Cells were isolated from longitudinal muscle myenteric plexus (LMMP). Cytokine receptor expression, muscle contractility, and muscarinic agonist receptor characteristics were examined by agonist displacement of [N-methyl-(3)H]scopolamine ([(3)H]NMS) binding. The TGF-beta1 receptor (543 bp) and the IFN-gamma receptor 1 (660 bp) were identified on smooth muscle cells. Scatchard analysis revealed dissociation constant and maximum binding values for [(3)H]NMS of 2.6 nM and 2.4 x 10(4) sites/cell, respectively, in control cells. Nematode infection was accompanied by a reduction in inhibitory constant of the high-affinity sites (K(H)), and this was independent of signal transduction and activator of transcription 6. Preincubation with TGF-beta1 enhanced longitudinal muscle contractility and decreased the K(H) to 2.2 pM (increased muscarinic receptor affinity), whereas preincubation with IFN-gamma increased the K(H) to 0.4 muM (decreased muscarinic receptor affinity) and decreased longitudinal muscle contractility. Preincubation of LMMP with IL-13 decreased the K(H) to 0.2 nM. Cytokines exert differential effects on the muscarinic receptor on intestinal longitudinal smooth muscle. These findings explain the basis for altered muscle contractility observed in Th1 and Th2 models of inflammation, as well as in the post-nematode-infected state.
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Affiliation(s)
- Hirotada Akiho
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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Mu ZB, Huang YX, Zhao BM, Liu ZX, Zhang BH, Wang QL. Effect of explosive noise on gastrointestinal transit and plasma levels of polypeptide hormones. World J Gastroenterol 2006; 12:2284-7. [PMID: 16610038 PMCID: PMC4087663 DOI: 10.3748/wjg.v12.i14.2284] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effect of firing noise on gastrointestinal transit and probe its mechanism by measuring the levels of plasma polypeptide hormones.
METHODS: A total of 64 SD rats were randomly divided into a control group and three stimulating groups. Firing noise of different intensity by sub-machine guns was used as inflicting factor. The effect of firing noise on liquid substance gastrointestinal transit and solid substance gastrointestinal transit was observed by measuring the ratio of carbon powder suspension transmitting and barium sticks transmitting respectively. Plasma levels of polypeptide hormones were measured by radio-immunoassay.
RESULTS: The noise accelerated gastrointestinal transit of solid food by more than 80 db;and accelerated gastrointestinal transit of liquid food significantly by more than 120 db. Meantime, plasma levels of plasma motilin (MTL)(157.47±16.08; 151.90±17.08), somatostatin (SS)(513.97±88.77; 458.25±104.30), substance P (SP)(115.52±20.70; 110.28±19.96) and vasoactive intestinal peptide (VIP) (214.21±63.17; 251.76±97.24) remarkably changed also.
CONCLUSION: Within a certain intensity range, the firing noise changes the levels of rat plasma gastrointestinal hormones, but the gastrointestinal transit is still normal. Beyond the range, the noise induces plasma hormone levels disturbance and gastrointestinal transit disorder.
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Affiliation(s)
- Zhen-Bin Mu
- Department of Gastroenterology, Tang Du Hospital of the Fourth Military Medical University, Xi'an 710038, Shaanxi Province, China.
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Abstract
BACKGROUND Infants' healthy growth and development are predicated, in part, on regular functioning of the gastrointestinal (GI) tract. In the first 6 months of life, infants typically double their birth weights. During this period of intense growth, the GI tract needs to be highly active and to function optimally. Identifying modifiable causes of GI tract dysregulation is important for understanding the pathophysiologic processes of such dysregulation, for identifying effective and efficient interventions, and for developing early prevention and health promotion strategies. One such modifiable cause seems to be maternal smoking, both during and after pregnancy. Purpose. This article brings together information that strongly suggests that infants' exposure to tobacco smoke is linked to elevated blood motilin levels, which in turn are linked to an increased risk of GI dysregulation, including colic and acid reflux. We base this hypothesis on evidence supporting a link between maternal smoking and infantile colic (IC) and on additional evidence proposing increased motilin release, attributable to exposure to tobacco smoke and its metabolites, as a physiologic mechanism linking maternal smoking with infantile GI dysregulation. METHODS We critically review and synthesize epidemiologic, physiologic, and biological evidence pertaining to smoking and colic, smoking and motilin levels, and motilin and colic. RESULTS Six studies have investigated the link between maternal smoking and IC, but IC was defined according to Wessel's rule of threes (crying for > or =3 hours per day, > or =3 days per week, for > or =3 weeks) in only 1 of these studies. The remaining studies used definitions that ranged from less-stringent variations of Wessel's criteria to definitions that would suggest excessive crying but not necessarily colic. Results from 5 of these studies suggest that there is an independent association between maternal smoking and excessive crying, as well as IC. Recent studies of the GI system provide strong, but indirect, corroborating evidence suggesting physiologic pathways through which maternal smoking can be linked to IC. This physiologic evidence can be outlined as follows: (1) smoking is linked to increased plasma and intestinal motilin levels and (2) higher-than-average levels of motilin are linked to elevated risks of IC. Although these findings from disparate fields suggest a physiologic mechanism linking maternal smoking with IC, the entire chain of events has not been examined in a single cohort. A prospective study, begun in pregnancy and continuing through the first 4 months of life, could provide definitive evidence linking these disparate lines of research. Key points for such a study are considered. CONCLUSIONS New epidemiologic evidence suggests that exposure to cigarette smoke and its metabolites may be linked to IC. Moreover, studies of the GI system provide corroborating evidence that suggests that (1) smoking is linked to increased plasma and intestinal motilin levels and (2) higher-than-average intestinal motilin levels are linked to elevated risks of IC. In the United States, nearly one-half of all women smokers continue to smoke during their pregnancies. This amounts to approximately 12% of all women who give birth. Moreover, it is estimated that 50% to 80% of employed adults have regular exposure to environmental tobacco smoke and that >30% of nonsmokers live with smokers. If, as we suspect, exposure to cigarette smoke increases the risk of colic, then this would provide additional incentives to parents to abstain from smoking. Decreased exposure to tobacco smoke can be expected to provide widespread and long-term health benefits to maternal and child populations.
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Affiliation(s)
- Edmond D Shenassa
- Department of Community Health and Centers for Behavioral and Preventive Medicine, Brown Medical School, One Hoppin St, Suite 500, Providence, RI 02903, USA.
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Wells RW, Blennerhassett MG. Persistent and selective effects of inflammation on smooth muscle cell contractility in rat colitis. Pflugers Arch 2004; 448:515-24. [PMID: 15107998 DOI: 10.1007/s00424-004-1286-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2004] [Accepted: 03/23/2004] [Indexed: 10/26/2022]
Abstract
Intestinal inflammation affects smooth muscle contractility contributing to altered motility, but changes to the individual smooth muscle cells are not well described. We used video microscopy to study the contractility of circular smooth muscle cells (CSMC) isolated from the rat mid-descending colon throughout the course of TNBS-induced colitis, measuring their shortening response to carbachol (CCh), 5-HT, histamine or high K(+). In control CSMC, CCh caused a maximal shortening response of 28 (2%), similar to that for 5-HT of 27 (1%), but by day 4 of colitis, these responses were decreased by 35% and 37%, respectively. By day 36, all aspects of cholinergic contraction returned to control levels, while 5-HT-induced contraction remained significantly attenuated. In contrast, the contractile responses to histamine remained similar at all time points. K(+)-induced contraction was impaired only on day 4, and the maximal response remained substantially greater than CCh or 5-HT. Colitis caused a 121% increase in CSMC length by day 2 that persisted through day 36, independent evidence for phenotypic change. We conclude that impaired CSMC contractility at both the receptor and non-receptor levels contribute to altered smooth muscle function during colitis. Persistent changes in contractile response remained detectable after resolution of inflammation, and similar events may occur in post-enteritis syndromes seen in humans.
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Affiliation(s)
- R W Wells
- Gastrointestinal Diseases Research Unit, Queen's University, K7L 5G2, Kingston, Ontario, Canada
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Kingham PJ, McLean WG, Walsh MT, Fryer AD, Gleich GJ, Costello RW. Effects of eosinophils on nerve cell morphology and development: the role of reactive oxygen species and p38 MAP kinase. Am J Physiol Lung Cell Mol Physiol 2003; 285:L915-24. [PMID: 12794004 DOI: 10.1152/ajplung.00094.2003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The adhesion of eosinophils to nerve cells and the subsequent release of eosinophil products may contribute to the pathogenesis of conditions such as asthma and inflammatory bowel disease. In this study we have separately examined the consequences of eosinophil adhesion and degranulation for nerve cell morphology and development. Eosinophils induced neurite retraction of cultured guinea pig parasympathetic nerves and differentiated IMR32 cholinergic neuroblastoma cells. Inhibition of eosinophil adhesion to IMR32 cells attenuated this retraction. Eosinophil adhesion to IMR32 cells led to tyrosine phosphorylation of a number of nerve cell proteins, activation of p38 MAP kinase, and generation of neuronal reactive oxygen species (ROS). Inhibition of tyrosine kinases with genistein prevented both the generation of ROS in the nerve cells and neurite retraction. The p38 MAP kinase inhibitor SB-239063 prevented neurite retraction but had no effect on the induction of ROS. Thus eosinophils induced neurite retraction via two distinct pathways: by generation of tyrosine kinase-dependent ROS and by p38 MAP kinase. Eosinophils also prevented neurite outgrowth during differentiation of IMR32 cells. In contrast to their effect on neurite retraction, this effect was mimicked by medium containing products released from eosinophils and by eosinophil major basic protein. These results indicate that eosinophils modify the morphology of nerve cells by distinct mechanisms that involve adhesion and released proteins.
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Affiliation(s)
- Paul J Kingham
- Dept. of Pharmacology and Therapeutics, Univ. of Liverpool, The Sherrington Bldgs., Ashton St., Liverpool L69 3GE, UK
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Depoortere I, Thijs T, Thielemans L, Peeters TL. Mechanisms involved in the loss of excitatory post-stimulus responses by inflammation. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2003; 367:245-52. [PMID: 12644896 DOI: 10.1007/s00210-003-0696-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2002] [Accepted: 01/07/2003] [Indexed: 10/25/2022]
Abstract
AIM Electrical stimulation of colonic muscles elicits a response during the stimulation period, and a transient excitation after the stimulus. Post-stimulus or "rebound" excitation has been linked to pathways involving inhibitory neurotransmitters, prostaglandins and substance P but the mechanism is incompletely understood. Because rabbit colitis is characterized by a loss of inhibitory neurotransmission we hypothesized it might affect the rebound response. Therefore we characterized rebound responses in non-inflamed and inflamed tissue by comparing the effect of antagonists/blockers of putative (nitric oxide [NO], ATP, substance P, prostaglandins) and new (serotonin) neurotransmitters. METHODS Strips from rabbits with colitis induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS) were subjected to electrical field stimulation. Because rebound responses are more prominent under nonadrenergic noncholinergic (NANC) conditions, the effect of specific antagonists (N(omega)-nitro-L-arginine methyl ester (L-NAME), indomethacin, SR140333, methiothepin) on the rebound response was compared under normal and NANC conditions. RESULTS NANC-conditions increased rebound responses in non-inflamed strips, but this effect was reduced or abolished in inflamed strips. Rebound responses were reduced by pretreatment with the NO-synthase inhibitor, L-NAME, under NANC conditions in non-inflamed strips but not affected in inflamed tissue. In contrast, the P(2) purine receptor antagonist, suramin, did not affect rebound responses in inflamed and non-inflamed strips. The effect of the cyclo-oxygenase inhibitor (COX), indomethacin, on rebound responses was reversed from excitatory to inhibitory by inflammation. Under NANC conditions rebound contractions were also reduced by the neurokinin-1 (NK(1)) antagonist, SR140333, both in normal and inflamed strips. The most pronounced reduction in rebound responses in inflamed and non-inflamed strips under normal conditions was observed with the 5-hydroxytryptamin (1,2) (5-HT(1,2)) antagonist, methiothepin. CONCLUSION Rebound responses are mainly non-cholinergic and involve NO, substance P, serotonin and inhibitory prostaglandins. In inflamed tissue the nitrergic pathway is absent, excitatory prostaglandins prevail and the cholinergic and tachykinergic components are relatively more important. However there remains an important serotonergic contribution. Our data suggest that inflammation damages different neural pathways to a different extent and is most selective for nitrergic pathways.
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Affiliation(s)
- Inge Depoortere
- Department of Pathophysiology, Center for Gastroenterological Research, University of Leuven, Gasthuisberg O and N, 3000 Leuven, Belgium.
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Depoortere I, Thijs T, Peeters TL. Generalized loss of inhibitory innervation reverses serotonergic inhibition into excitation in a rabbit model of TNBS-colitis. Br J Pharmacol 2002; 135:2011-9. [PMID: 11959805 PMCID: PMC1573313 DOI: 10.1038/sj.bjp.0704648] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
1. Inflammation may affect subpopulations of neurons of the myenteric plexus. 2. In the present study the effect of trinitrobenzene sulphonic acid (TNBS) induced colitis on nitrergic, purinergic and adrenergic inhibitory neurotransmission was studied as well as the consequences of the related changes on the response of 5-HT agonists using these neurotransmitters to mediate their effect. 3. Strips from normal and colitis rabbits (135 mg kg(-1) TNBS) were subjected to electrical field stimulation (EFS, 0.3 ms, 6V, 0.5 - 32 Hz, 10 s train). The response was measured isometrically in the absence or presence of L-NAME, suramin, guanethidine, the 5-HT agonists (5-HT(1/5A/7): 5-carboxamidotryptamine (5-CT), 5-HT(2): alpha-methyl-5-HT, 5-HT(3): 2-methyl-5-HT, 5-HT(4): 5-methoxytryptamine (5-MeOT)) or a combination. 4. In normal strips L-NAME (1 - 32 Hz), suramin (0.5 - 2, 8 Hz) and guanethidine (4, 16, 32 Hz) increased the response to EFS. This effect was abolished in inflamed strips and was accompanied by a decrease in nNOS expression. 5. In normal strips all 5-HT agonists induced pronounced (5-CT, alpha-methyl-5-HT) or small (2-methyl-5-HT, 5-MeOT) inhibitory neural responses. In inflamed strips this was reversed to cholinergic excitatory responses. 6. The effect of inflammation on the 5-HT(4) response was mimicked by preincubation of normal strips with L-NAME or suramin. Accordingly, in inflamed strips L-NAME or suramin did not affect the excitatory effects of 5-MeOT. 7. TNBS-colitis abolishes nitrergic, purinergic and adrenergic neurotransmission. This reverses serotonergic inhibition into excitation.
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Affiliation(s)
- Inge Depoortere
- Centre for Gastroenterological Research, Department of Pathophysiology, University of Leuven, B-3000 Leuven, Belgium.
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