Publications by authors named "Clodagh Prendergast"

18 Publications

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HYPOXIA AND REPRODUCTIVE HEALTH: Hypoxia and labour.

Reproduction 2021 Jan;161(1):F67-F80

Department of Women's and Children's Health, University of Liverpool, Liverpool, Merseyside, UK.

Intermittent myometrial hypoxia is a normal feature of labour, as the powerful contractions compress blood vessels. In this review, we focus on the relation between hypoxia, myometrial metabolism, and contractility. We dissect how hypoxia can feedback and limit an ongoing contraction and help prevent foetal distress. The mechanisms involve acidification from lactate, decreased excitability, and a fall of intracellular calcium concentration. As this cycle of contraction and relaxation repeats in labour, the hypoxia also engenders mechanisms that increase force; hypoxia-induced force increase, HIFI. We also discuss the role of the myometrial blood vessels in dysfunctional labour, which is associated with lactic acidosis. In synthesising these studies, we have attempted to unify findings by considering the importance of experimental protocols and finding direct mechanistic evidence from human myometrium or in vivo studies. We have made suggestions for future studies to fill the holes in our understanding and speed up the translation of our knowledge to improve births for mothers and babies everywhere.
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http://dx.doi.org/10.1530/REP-20-0327DOI Listing
January 2021

Justicia flava leaf extract potently relaxes pregnant human myometrial contractility: a lead plant for drug discovery of new tocolytic drugs.

Exp Physiol 2020 12 2;105(12):2033-2037. Epub 2020 Nov 2.

Department of Women and Children's Health, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK.

New Findings: What is the central question of this study? Can Justicia flava leaf extract (JF) inhibit human myometrial contractility as was previously shown in mouse myometrium? What is the main finding and its importance? JF abolished human myometrial contractions and therefore presents as a lead plant in drug discovery studies involving drugs for preterm birth.

Abstract: In the search for new potent therapies for preterm labour, Justicia flava leaf extract (JF) was previously shown to potently inhibit uterine contractility in both pregnant and non-pregnant mouse uterus. This study took the investigation a step further and investigated the activity of JF on pregnant human myometrial contractility. JF potently inhibited human myometrial contractility in a concentration-dependent manner. This pilot study provides evidence that JF should be further investigated as a lead plant in the drug discovery of new uterine relaxants.
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http://dx.doi.org/10.1113/EP088819DOI Listing
December 2020

Human myometrial artery function and endothelial cell calcium signalling are reduced by obesity: Can this contribute to poor labour outcomes?

Acta Physiol (Oxf) 2019 12 1;227(4):e13341. Epub 2019 Aug 1.

Department of Molecular and Cellular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK.

Aims: Determining how obesity affects function in human myometrial arteries, to help understand why childbirth has poor outcomes in obese women.

Methods: Myometrial arteries were studied from 84 biopsies. Contraction (vasopressin and U-46619) and relaxation (carbachol, bradykinin, SNAP) was assessed using wire myography. eNOS activity was assessed using L-NAME. Cholesterol was reduced using methyl-β-cyclodextrin to determine whether it altered responses. Differences in endothelial cell intracellular Ca signalling were assessed using confocal microscopy.

Results: The effects of BMI on relaxation were agonist specific and very marked; all vessels, irrespective of BMI, relaxed to bradykinin but 0% of vessels (0/13) from obese women relaxed to carbachol, compared to 59% (10/17) from normal weight women. Cholesterol-lowering drugs did not restore carbachol responses (n = 6). All vessels, irrespective of BMI, relaxed when NO was directly released by SNAP (n = 19). Inhibition of eNOS with L-NAME had a significant effect in normal but not overweight/obese vessels. Compared to bradykinin, a lower proportion of endothelial cells responded to carbachol and the amplitude of the calcium response was significantly less, in all vessels. Furthermore, a significantly lower proportion of endothelial cells responded to carbachol in the overweight/obese group compared to control. In contrast to relaxation, the effect of contractile agonists was unchanged with increasing BMI.

Conclusions: The ability of human myometrial arteries to relax is significantly impaired with obesity, and our data suggest this is due to a deficit in endothelial calcium signalling. This inability to recover following compression during contractions, might contribute to poor labours in obese women.
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http://dx.doi.org/10.1111/apha.13341DOI Listing
December 2019

The Myometrium: From Excitation to Contractions and Labour.

Adv Exp Med Biol 2019 ;1124:233-263

Department of Cellular and Molecular Physiology, Harris-Wellbeing Preterm Birth Centre, Institute of Translational Medicine, University of Liverpool, Liverpool, UK.

We start by describing the functions of the uterus, its structure, both gross and fine, innervation and blood supply. It is interesting to note the diversity of the female's reproductive tract between species and to remember it when working with different animal models. Myocytes are the overwhelming cell type of the uterus (>95%) and our focus. Their function is to contract, and they have an intrinsic pacemaker and rhythmicity, which is modified by hormones, stretch, paracrine factors and the extracellular environment. We discuss evidence or not for pacemaker cells in the uterus. We also describe the sarcoplasmic reticulum (SR) in some detail, as it is relevant to calcium signalling and excitability. Ion channels, including store-operated ones, their contributions to excitability and action potentials, are covered. The main pathway to excitation is from depolarisation opening voltage-gated Ca channels. Much of what happens downstream of excitability is common to other smooth muscles, with force depending upon the balance of myosin light kinase and phosphatase. Mechanisms of maintaining Ca balance within the myocytes are discussed. Metabolism, and how it is intertwined with activity, blood flow and pH, is covered. Growth of the myometrium and changes in contractile proteins with pregnancy and parturition are also detailed. We finish with a description of uterine activity and why it is important, covering progression to labour as well as preterm and dysfunctional labours. We conclude by highlighting progress made and where further efforts are required.
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http://dx.doi.org/10.1007/978-981-13-5895-1_10DOI Listing
August 2019

Atherosclerosis differentially affects calcium signalling in endothelial cells from aortic arch and thoracic aorta in Apolipoprotein E knockout mice.

Physiol Rep 2014 Oct 24;2(10). Epub 2014 Oct 24.

Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK.

Apolipoprotein-E knockout (ApoE(-/-)) mice develop hypercholesterolemia and are a useful model of atherosclerosis. Hypercholesterolemia alters intracellular Ca(2+) signalling in vascular endothelial cells but our understanding of these changes, especially in the early stages of the disease process, is limited. We therefore determined whether carbachol-mediated endothelial Ca(2+) signals differ in plaque-prone aortic arch compared to plaque-resistant thoracic aorta, of wild-type and ApoE(-/-) mice, and how this is affected by age and the presence of hypercholesterolemia. The extent of plaque development was determined using en-face staining with Sudan IV. Tissues were obtained from wild-type and ApoE(-/-) mice at 10 weeks (pre-plaques) and 24 weeks (established plaques). We found that even before development of plaques, significantly increased Ca(2+) responses were observed in arch endothelial cells. Even with aging and plaque formation, ApoE(-/-) thoracic responses were little changed, however a significantly enhanced Ca(2+) response was observed in arch, both adjacent to and away from lesions. In wild-type mice of any age, 1-2% of cells had oscillatory Ca(2+) responses. In young ApoE(-/-) and plaque-free regions of older ApoE(-/-), this is unchanged. However a significant increase in oscillations (~13-15%) occurred in thoracic and arch cells adjacent to lesions in older mice. Our data suggest that Ca(2+) signals in endothelial cells show specific changes both before and with plaque formation, that these changes are greatest in plaque-prone aortic arch cells, and that these changes will contribute to the reported deterioration of endothelium in atherosclerosis.
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http://dx.doi.org/10.14814/phy2.12171DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4254096PMC
October 2014

Atherosclerosis affects calcium signalling in endothelial cells from apolipoprotein E knockout mice before plaque formation.

Cell Calcium 2014 Mar 22;55(3):146-54. Epub 2014 Feb 22.

Department of Cellular & Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom.

Little is known about how hypercholesterolaemia affects Ca(2+) signalling in the vasculature of ApoE(-/-) mice, a model of atherosclerosis. Our objectives were therefore to determine (i) if hypercholesterolaemia alters Ca(2+) signalling in aortic endothelial cells before overt atherosclerotic lesions occur, (ii) how Ca(2+) signals are affected in older plaque-containing mice, and (iii) whether Ca(2+) signalling changes were translated into contractility differences. Using confocal microscopy we found agonist-specific Ca(2+) changes in endothelial cells. ATP responses were unchanged in ApoE(-/-) cells and methyl-β-cyclodextrin, which lowers cholesterol, was without effect. In contrast, Ca(2+) signals to carbachol were significantly increased in ApoE(-/-) cells, an effect methyl-β-cyclodextrin reversed. Ca(2+) signals were more oscillatory and store-operated Ca(2+) entry decreased as mice aged and plaques formed. Despite clearly increased Ca(2+) signals, aortic rings pre-contracted with phenylephrine had impaired relaxation to carbachol. This functional deficit increased with age, was not related to ROS generation, and could be partially rescued by methyl-β-cyclodextrin. In conclusion, carbachol-induced calcium signalling and handling are significantly altered in endothelial cells of ApoE(-/-) mice before plaque development. We speculate that reduction in store-operated Ca(2+) entry may result in less efficient activation of eNOS and thus explain the reduced relaxatory response to CCh, despite the enhanced Ca(2+) response.
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http://dx.doi.org/10.1016/j.ceca.2014.02.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4024193PMC
March 2014

JNJ-26070109 [(R)4-bromo-N-[1-(2,4-difluoro-phenyl)-ethyl]-2-(quinoxaline-5-sulfonylamino)-benzamide]: a novel, potent, and selective cholecystokinin 2 receptor antagonist with good oral bioavailability.

J Pharmacol Exp Ther 2011 Jul 14;338(1):328-36. Epub 2011 Apr 14.

Johnson & Johnson Pharmaceutical Research & Development, LLC San Diego, California 92101, USA.

JNJ-26070109 [(R)4-bromo-N-[1-(2,4-difluoro-phenyl)-ethyl]-2-(quinoxaline-5-sulfonylamino)-benzamide] is a representative of a new chemical class of competitive antagonists of cholecystokinin 2 (CCK2) receptors. In this study, the primary in vitro pharmacology of JNJ-26070109 was evaluated along with the pharmacokinetic and pharmacodynamic properties of this compound in rat and canine models of gastric acid secretion. JNJ-26070109 expressed high affinity for human (pK(I) = 8.49 ± 0.13), rat (pK(I) = 7.99 ± 0.08), and dog (pK(I) = 7.70 ± 0.14) CCK2 receptors. The selectivity of JNJ-26070109 at the CCK2 receptor versus the CCK1 receptor was species-dependent, with the greatest degree of selectivity (>1200-fold) measured at the human isoforms of the CCK1 receptor (selectivity at CCK2 versus CCK1 receptors: human, ∼1222-fold; rat, ∼324-fold; dog ∼336-fold). JNJ-26070109 behaved as a surmountable, competitive, antagonist of human CCK2 receptors in a calcium mobilization assay (pK(B) = 8.53 ± 0.05) and in pentagastrin-stimulated gastric acid secretion in the isolated, lumen-perfused, mouse stomach assay (pK(B) = 8.19 ± 0.13). The pharmacokinetic profile of this compound was determined in vivo in rats and dogs. JNJ-26070109 was shown to have high oral bioavailability (%F rat = 73 ± 16; %F dog = 92 ± 12) with half lives of 1.8 ± 0.3 and 1.2 ± 0.1 h in rat and dog, respectively. The pharmacodynamic properties of this compound were investigated using two in vivo models. In conscious rat and dog chronic gastric fistula models of pentagastrin-stimulated acid secretion, JNJ-26070109 had oral EC(50) values of 1.5 and 0.26 μM, respectively. Overall, we have demonstrated that JNJ-26070109 is a high-affinity, selective CCK2 receptor antagonist with good pharmacokinetic properties.
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http://dx.doi.org/10.1124/jpet.110.178483DOI Listing
July 2011

Targeting gastrin for the treatment of gastric acid related disorders and pancreatic cancer.

Trends Pharmacol Sci 2011 Apr 10;32(4):201-5. Epub 2011 Mar 10.

Johnson & Johnson Pharmaceutical Research & Development, L.L.C., 3210 Merryfield Row, San Diego, CA 92121, USA.

Gastrin, acting through peripheral cholecystokinin (CCK) 2 receptors, is a major hormonal regulator of gastric acid secretion. The effects of gastrin on acid secretion occur both acutely and chronically because gastrin directly stimulates gastric acid secretion and also exerts trophic effects on the enterochromaffin-like and parietal cells that together constitute the acid secretory apparatus of the stomach. Several antagonists that target the CCK2 receptor have been identified and investigated for the treatment of gastroesophageal reflux disease and pancreatic cancer. In this paper, we discuss the contribution of gastrin to these disease pathologies and the data generated to date from clinical studies investigating CCK2 receptor antagonists.
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http://dx.doi.org/10.1016/j.tips.2011.02.003DOI Listing
April 2011

Cholesterol depletion alters coronary artery myocyte Ca(2+) signalling in a stimulus-specific manner.

Cell Calcium 2010 Jan;47(1):84-91

University of Liverpool, Merseyside, UK.

Although there is evidence that caveolae and cholesterol play an important role in myocyte signalling processes, details of the mechanisms involved remain sparse. In this paper we have studied for the first time the clinically relevant intact coronary artery and measured in situ Ca(2+) signals in individual myocytes using confocal microscopy. We have examined the effect of the cholesterol-depleting agents, methyl-cyclodextrin (MCD) and cholesterol oxidase, on high K(+), caffeine and agonist-induced Ca(2+) signals. We find that cholesterol depletion produces a stimulus-specific alteration in Ca(2+) responses; with 5-HT (10microM) and endothelin-1 (10nM) responses being selectively decreased, the phenylephrine response (100microM) increased and the responses to high K(+) (60mM) and caffeine (10mM) unaffected. Agonist-induced Ca(2+) signals were restored when cholesterol was replenished using cholesterol-saturated MCD. In additional experiments, enzymatically isolated myocytes were patch clamped. We found that cholesterol depletion caused a selective modification of ion channel function, with whole cell inward Ca(2+) current being unaltered, whereas outward K(+) current was increased, due to BK(Ca) channel activation. There was also a significant decrease in cell capacitance. These data are discussed in terms of the involvement of caveolae in receptor localisation, Ca(2+) entry pathways and SR Ca(2+) release, and the role of these in agonist signalling.
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http://dx.doi.org/10.1016/j.ceca.2009.11.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824115PMC
January 2010

Anthranilic sulfonamide CCK1/CCK2 dual receptor antagonists II: tuning of receptor selectivity and in vivo efficacy.

Bioorg Med Chem Lett 2009 Nov 23;19(22):6376-8. Epub 2009 Sep 23.

Johnson & Johnson Pharmaceutical Research and Development, L.L.C., 3210 Merryfield Row, San Diego, CA 92121, USA.

In the previous article we demonstrated how certain CCK2R-selective anthranilic amides could be structurally modified to afford high-affinity, selective CCK1R activity. We now describe our efforts at modulating and optimizing the CCK1R and CCK2R affinities aimed at producing compounds with good pharmacokinetics properties and in vivo efficacy in rat models of gastric acid and pancreatic amylase secretion.
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http://dx.doi.org/10.1016/j.bmcl.2009.09.065DOI Listing
November 2009

Anthranilic sulfonamide CCK1/CCK2 dual receptor antagonists I: discovery of CCKR1 selectivity in a previously CCKR2-selective lead series.

Bioorg Med Chem Lett 2009 Nov 23;19(22):6373-5. Epub 2009 Sep 23.

Johnson & Johnson Pharmaceutical Research and Development, L.L.C., 3210 Merryfield Row, San Diego, CA 92121, USA.

A series of CCK2R-selective anthranilic amides is shown to derive CCK1R affinity via selective substitution of the amide side chain. Thus, extending the length of the original benzamide side chain by a single methylene unit imparts CCK1R affinity to the series, and further fine tuning of the affinity results in CCK1R selectivity of greater than 100-fold.
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http://dx.doi.org/10.1016/j.bmcl.2009.09.064DOI Listing
November 2009

Discovery of potent cholecystokinin-2 receptor antagonists: elucidation of key pharmacophore elements by X-ray crystallographic and NMR conformational analysis.

Bioorg Med Chem 2008 Apr 5;16(7):3917-25. Epub 2008 Feb 5.

Johnson & Johnson Pharmaceutical Research and Development, L.L.C., Drug Discover, 3210 Merryfield Row, San Diego, CA 92121, USA.

A novel series of cholecystokinin-2 receptor (CCK-2R) antagonists has been identified, as exemplified by anthranilic sulfonamide 1 (pK(i)=7.6). Pharmacokinetic and stability studies indicated that this series of compounds suffered from metabolic degradation, and that both the benzothiadiazole and piperidine rings were rapidly oxidized by liver enzymes. A combination of synthesis, computational methods, (1)H NMR conformational studies, and X-ray crystallographic analyses were applied to elucidate key pharmacophore elements, and to discover analogs with improved pharmacokinetic profiles, and high receptor binding affinity and selectivity.
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http://dx.doi.org/10.1016/j.bmc.2008.01.059DOI Listing
April 2008

Synthesis and solid-phase purification of anthranilic sulfonamides as CCK-2 ligands.

Bioorg Med Chem Lett 2007 Dec 29;17(24):6905-9. Epub 2007 Sep 29.

Johnson & Johnson Pharmaceutical Research and Development, 3210 Merryfield Row, San Diego, CA 92121, USA.

A novel strategy for the synthesis of cholecystokinin-2 receptor ligands was developed. The route employs a solution-phase synthesis of a series of anthranilic sulfonamides followed by a resin capture purification strategy to produce multi-milligram quantities of compounds for bioassay. The synthesis was used to produce >100 compounds containing various functional groups, highlighting the general applicability of this strategy and to address specific metabolism issues in our CCK-2 program.
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http://dx.doi.org/10.1016/j.bmcl.2007.09.087DOI Listing
December 2007

3-[5-(3,4-Dichloro-phenyl)-1-(4-methoxy-phenyl)-1H-pyrazol-3-yl]-2-m-tolyl-propionate (JNJ-17156516), a novel, potent, and selective cholecystokinin 1 receptor antagonist: in vitro and in vivo pharmacological comparison with dexloxiglumide.

J Pharmacol Exp Ther 2007 Nov 7;323(2):562-9. Epub 2007 Aug 7.

Johnson & Johnson Pharmaceutical Research & Development L.L.C., San Diego, California 92121, USA.

3-[5-(3,4-Dichloro-phenyl)-1-(4-methoxy-phenyl)-1H-pyrazol-3-yl]-2-m-tolyl-propionate (JNJ-17156516) is a novel, potent, and selective cholecystokinin (CCK)1-receptor antagonist. In this study, the pharmacology of JNJ-17156516 was investigated both in vitro and in vivo, and the pharmacokinetic profile was evaluated in rats. JNJ-17156516 expressed high-affinity at the cloned human (pK(I) = 7.96 +/- 0.11), rat (pK(I) = 8.02 +/- 0.11), and canine (pK(I) = 7.98 +/- 0.04) CCK1 receptors, and it was also highly selective for the CCK1 receptor compared with the CCK2 receptor across the same species ( approximately 160-, approximately 230-, and approximately 75-fold, respectively). The high affinity of JNJ-17156516 at CCK1 receptors in vitro was confirmed in radioligand binding studies on fresh human gallbladder tissue (pK(I) = 8.22 +/- 0.05). In a functional in vitro assay of guinea pig gallbladder contraction, JNJ-17156516 behaved as a competitive antagonist, with a pK(B) value of 8.00 +/- 0.07. In vivo, JNJ-17156516 produced a parallel, rightward shift in the CCK-8S-evoked contraction of the guinea pig gallbladder. The dose required to shift the CCK-8S dose-response curve was 240 nmol kg(-1) i.v. In the anesthetized rat, JNJ-17156516 produced a dose-related decrease in the number of duodenal contractions evoked by infusion of CCK-8S, with an ED(50) = 484 nmol kg(-1). Pharmacokinetic analysis of JNJ-17156516 in rats, revealed that JNJ-17156516 had a half-life of 3.0 +/- 0.5 h and a very high bioavailability (108 +/- 10%) in this species. Overall, we have demonstrated that JNJ-17156516 is a high-affinity selective human CCK1 receptor antagonist with good pharmacokinetic properties in rats.
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http://dx.doi.org/10.1124/jpet.107.124578DOI Listing
November 2007

Identification and optimization of anthranilic sulfonamides as novel, selective cholecystokinin-2 receptor antagonists.

J Med Chem 2006 Oct;49(21):6371-90

Johnson and Johnson Pharmaceutical Research and Development, LLC, 3210 Merryfield Row, San Diego, California 92121, USA.

A high throughput screening approach to the identification of selective cholecystokinin-2 receptor (CCK-2R) ligands resulted in the discovery of a novel series of antagonists, represented by 1-[2-[(2,1,3-benzothiadiazol-4-ylsulfonyl)amino]-5-chlorobenzoyl]-piperidine (1; CCK-2R, pK(I) = 6.4). Preliminary exploration of the structure-activity relationships around the anthranilic ring and the amide and sulfonamide moieties led to a nearly 50-fold improvement of receptor affinity and showed a greater than 1000-fold selectivity over the related cholecystokinin-1 receptor. Pharmacokinetic evaluation led to the identification of 4-[4-iodo-2-[(5-quinoxalinylsulfonyl)amino]benzoyl]-morpholine, 26d, a compound that demonstrates promising pharmacokinetic properties in the rat and dog with respect to plasma clearance and oral bioavailability and is a potent inhibitor in vivo of pentagastrin-stimulated acid secretion in the rat when dosed orally.
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http://dx.doi.org/10.1021/jm060590xDOI Listing
October 2006

Neuromedin U stimulates contraction of human long saphenous vein and gastrointestinal smooth muscle in vitro.

Regul Pept 2006 Sep 19;136(1-3):109-16. Epub 2006 Jun 19.

Department of Surgery, Royal Free and University College Medical School, The Middlesex Hospital, Mortimer Street, London W1T 3AA, UK.

The neuropeptide Neuromedin U (NMU) stimulates smooth muscle contraction, and modulates local blood flow and adrenocortical function via two endogenous receptors, NMU1 and NMU2. Although its amino-acid sequence is highly conserved across species, the physiological effects of NMU are variable between species and little is known of its effects on human tissues. We have examined the contractile effects of NMU-25 on human smooth muscles of the gastrointestinal (GI) tract (ascending colon, gallbladder) and long saphenous vein (LSV) using in vitro organ bath bioassays. From LSV, ileum, gallbladder, caecum and colon, NMU receptor transcripts were amplified by RT-PCR and expression levels were determined by semi-quantitative scanning densitometry. NMU-25 produced a concentration-dependent, sustained contraction of isolated smooth muscle (p[A](50)+/-s.e.m., ascending colon, 8.93+/-0.18; gallbladder, 7.01+/-0.15; LSV, 8.67+/-0.09). NMU1 and NMU2 receptor transcription was detected in all tissues; transcription of both receptors was similar in gallbladder, but NMU1 receptor transcription was predominant in the sigmoid colon and LSV. In summary, these studies indicate that NMU may control tone in the human GI tract and LSV through an action on smooth muscle. Development of NMU receptor subtype-selective ligands will aid the further elucidation of the physiological roles of NMU and its two receptors.
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http://dx.doi.org/10.1016/j.regpep.2006.05.003DOI Listing
September 2006

Species-dependent smooth muscle contraction to Neuromedin U and determination of the receptor subtypes mediating contraction using NMU1 receptor knockout mice.

Br J Pharmacol 2006 Apr;147(8):886-96

Johnson & Johnson Pharmaceutical Research & Development, L.L.C., 3210 Merryfield Row, San Diego, CA 92121, USA.

The peptide ligand neuromedin U (NMU) has been implicated in an array of biological activities, including contraction of uterine, intestinal and urinary bladder smooth muscle. However, many of these responses appear to be species-specific. This study was undertaken to fully elucidate the range of smooth muscle-stimulating effects of NMU in rats, mice and guinea-pigs, and to examine the extent of the species differences. In addition, the NMU1 receptor knockout mouse was used to determine which receptor subtype mediates the contractile responses generated by NMU in the mouse. A range of isolated organ in vitro bioassays were carried out, which were chosen to re-confirm previous literature reports (uterine and stomach fundus contraction) and also to explore potentially novel smooth muscle responses to NMU. This investigation uncovered a number of previously unidentified NMU-mediated responses: contraction of rat lower esophageal sphinster (LES), rat ileum, mouse gallbladder, enhancement of electrically evoked contractions in rat and mouse vas deferens, and a considerable degree of cross-species differences. Studies using the NMU1 receptor knockout mice revealed that in the mouse fundus and gallbladder assays the NMU contractile response was mediated entirely through the NMU1 receptor subtype, whereas, in assays of mouse uterus and vas deferens, the response to NMU was unchanged in the NMU1 receptor knockout mouse, suggesting that the NMU response may be mediated through the NMU2 receptor subtype. NMU receptor subtype-selective antagonists are required to further elucidate the role of the individual receptor subtypes.
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http://dx.doi.org/10.1038/sj.bjp.0706677DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1760708PMC
April 2006

TNF alpha reduces tachykinin, PGE2-dependent, relaxation of the cultured mouse trachea by increasing the activity of COX-2.

Br J Pharmacol 2005 Jan;144(2):220-30

Laboratory of Clinical and Experimental Allergy Research, Department of Otorhinolaryngology, Malmö University Hospital, Malmö SE-20502, Sweden.

1. Chronic inflammation is a central feature of asthma. The inflammatory cytokine tumour necrosis factor alpha (TNFalpha) has been implicated in this disease, and is known to alter airway smooth muscle functionally. 2. The aim of this study was to investigate the influence of TNFalpha on tachykinin-induced airway relaxation. Mouse tracheae were cultured in the absence and presence of TNFalpha for 1 or 4 days. 3. In the absence of TNFalpha, substance P (SP) and neurokinin A (NKA) induced comparable levels of relaxation in fresh and cultured segments. Functional studies with selective antagonists/inhibitors indicated that the relaxation was mediated by the NK(1) receptor coupled to cyclooxygenase (COX)-2 activation and subsequent release of prostaglandin E(2) (PGE(2)). TNFalpha attenuated SP- and NKA-induced relaxation in a time- and concentration-dependent manner, decreasing the ability of PGE(2) to relax tissues. 4. Further studies indicated that TNFalpha elevated COX-2 activity and that concomitant inhibition of COX-2 reversed TNFalpha-attenuated PGE(2) relaxation. Culture with PGE(2) decreased SP- and PGE(2)-mediated relaxation, further implicating the activity of COX-2 in the attenuation of tachykinin signalling. 5. Gene expression analysis demonstrated that TNFalpha increased the expression of smooth muscle COX-2, PGE(2) synthase and EP(2) receptor mRNA, and decreased the expression of the EP(4) receptor. 6. Overall, these results show that NK(1) receptor-mediated relaxation induced by PGE(2) is attenuated by prolonged TNFalpha stimulation. Increased COX-2 activity induced by TNFalpha appears to be central to this process.
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http://dx.doi.org/10.1038/sj.bjp.0706067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1575996PMC
January 2005