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Unterköfler MS, McGorum BC, Milne EM, Licka TF. Establishment of a model for equine small intestinal disease: effects of extracorporeal blood perfusion of equine ileum on metabolic variables and histological morphology - an experimental ex vivo study. BMC Vet Res 2019; 15:400. [PMID: 31703590 PMCID: PMC6839147 DOI: 10.1186/s12917-019-2145-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 10/15/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In horses a number of small intestinal diseases is potentially life threatening. Among them are Equine Grass Sickness (EGS), which is characterised by enteric neurodegeneration of unknown aetiology, as well as reperfusion injury of ischaemic intestine (I/R), and post-operative ileus (POI), common after colic surgery. The perfusion of isolated organs is successfully used to minimize animal testing for the study of pathophysiology in other scenarios. However, extracorporeal perfusion of equine ileum sourced from horses slaughtered for meat production has not yet been described. Therefore the present study evaluated the potential of such a model for the investigation of small intestinal diseases in an ex vivo and cost-efficient system avoiding experiments in live animals. RESULT Nine ileum specimens were sourced from horses aged 1-10 years after routine slaughter at a commercial abattoir. Ileum perfusion with oxygenated autologous blood and plasma was successfully performed for 4 h in a warm isotonic bath (37.0-37.5 °C). Ileum specimens had good motility and overall pink to red mucosa throughout the experiment; blood parameters indicated good tissue vitality: 82 ± 34 mmHg mean arterial partial pressure of oxygen (pO2) compared to 50 ± 17 mmHg mean venous pO2, 48 ± 10 mmHg mean arterial partial pressure of carbon dioxide (pCO2) compared to 66 ± 7 mmHg venous pCO2 and 9.8 ± 2.8 mmol/L mean arterial lactate compared to 11.6 ± 2.7 mmol/L venous lactate. There was a mild increase in ileum mass reaching 105 ± 7.5% of the pre-perfusion mass after 4 hours. Histology of haematoxylin and eosin stained biopsy samples taken at the end of perfusion showed on average 99% (±1%) histologically normal neurons in the submucosal plexus and 76.1% (±23.9%) histologically normal neurons in the myenteric plexus and were not significantly different to control biopsies. CONCLUSION Extracorporeal, normothermic perfusion of equine ileum over 4 h using autologous oxygenated blood/plasma perfusate showed potential as experimental model to test whether haematogenous or intestinal exposure to neurotoxins suspected in the pathogenesis of EGS can induce neuronal damage typical for EGS. Also, this model may allow investigations into the effect of pharmaceuticals on I/R injury, as well as into the pathogenesis of equine POI.
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Affiliation(s)
- Maria S Unterköfler
- Department for Companion Animals and Horses, University Equine Hospital, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210, Vienna, Austria
| | - Bruce C McGorum
- Department of Veterinary Clinical Sciences, Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, UK
| | - Elspeth M Milne
- Department of Veterinary Clinical Sciences, Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, UK
| | - Theresia F Licka
- Department for Companion Animals and Horses, University Equine Hospital, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210, Vienna, Austria. .,Department of Veterinary Clinical Sciences, Royal (Dick) School of Veterinary Studies and The Roslin Institute, The University of Edinburgh, Easter Bush Campus, Midlothian, EH25 9RG, UK.
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Abot A, Lucas A, Bautzova T, Bessac A, Fournel A, Le-Gonidec S, Valet P, Moro C, Cani PD, Knauf C. Galanin enhances systemic glucose metabolism through enteric Nitric Oxide Synthase-expressed neurons. Mol Metab 2018; 10:100-108. [PMID: 29428595 PMCID: PMC5985240 DOI: 10.1016/j.molmet.2018.01.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 01/12/2018] [Accepted: 01/23/2018] [Indexed: 12/14/2022] Open
Abstract
Objective Decreasing duodenal contraction is now considered as a major focus for the treatment of type 2 diabetes. Therefore, identifying bioactive molecules able to target the enteric nervous system, which controls the motility of intestinal smooth muscle cells, represents a new therapeutic avenue. For this reason, we chose to study the impact of oral galanin on this system in diabetic mice. Methods Enteric neurotransmission, duodenal contraction, glucose absorption, modification of gut–brain axis, and glucose metabolism (glucose tolerance, insulinemia, glucose entry in tissue, hepatic glucose metabolism) were assessed. Results We show that galanin, a neuropeptide expressed in the small intestine, decreases duodenal contraction by stimulating nitric oxide release from enteric neurons. This is associated with modification of hypothalamic nitric oxide release that favors glucose uptake in metabolic tissues such as skeletal muscle, liver, and adipose tissue. Oral chronic gavage with galanin in diabetic mice increases insulin sensitivity, which is associated with an improvement of several metabolic parameters such as glucose tolerance, fasting blood glucose, and insulin. Conclusion Here, we demonstrate that oral galanin administration improves glucose homeostasis via the enteric nervous system and could be considered a therapeutic potential for the treatment of T2D. Targeting the enteric nervous system (ENS) is an innovative solution to treat diabetes. The ENS controls duodenal contractions to modulate glycemia via the gut–brain axis. ENS/contractions are targeted by the neuropeptide galanin in the intestine. Oral galanin treatment decreases duodenal hyper-contractility in diabetic mice. Oral galanin restores the gut–brain axis to improve glycemia in diabetic mice.
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Affiliation(s)
- Anne Abot
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1220, Université Paul Sabatier, UPS, Institut de Recherche en Santé Digestive et Nutrition (IRSD), CHU Purpan, Place du Docteur Baylac, CS 60039, 31024 Toulouse Cedex 3, France; NeuroMicrobiota, European Associated Laboratory (EAL) INSERM/UCL, France
| | - Alexandre Lucas
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1048, Université Paul Sabatier, UPS, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), CHU Rangueil, 1 Avenue Jean Poulhès, BP84225, 31432 Toulouse Cedex 4, France
| | - Tereza Bautzova
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1220, Université Paul Sabatier, UPS, Institut de Recherche en Santé Digestive et Nutrition (IRSD), CHU Purpan, Place du Docteur Baylac, CS 60039, 31024 Toulouse Cedex 3, France; NeuroMicrobiota, European Associated Laboratory (EAL) INSERM/UCL, France
| | - Arnaud Bessac
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1220, Université Paul Sabatier, UPS, Institut de Recherche en Santé Digestive et Nutrition (IRSD), CHU Purpan, Place du Docteur Baylac, CS 60039, 31024 Toulouse Cedex 3, France; NeuroMicrobiota, European Associated Laboratory (EAL) INSERM/UCL, France
| | - Audren Fournel
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1220, Université Paul Sabatier, UPS, Institut de Recherche en Santé Digestive et Nutrition (IRSD), CHU Purpan, Place du Docteur Baylac, CS 60039, 31024 Toulouse Cedex 3, France; NeuroMicrobiota, European Associated Laboratory (EAL) INSERM/UCL, France
| | - Sophie Le-Gonidec
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1048, Université Paul Sabatier, UPS, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), CHU Rangueil, 1 Avenue Jean Poulhès, BP84225, 31432 Toulouse Cedex 4, France
| | - Philippe Valet
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1048, Université Paul Sabatier, UPS, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), CHU Rangueil, 1 Avenue Jean Poulhès, BP84225, 31432 Toulouse Cedex 4, France
| | - Cédric Moro
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1048, Université Paul Sabatier, UPS, Institut des Maladies Métaboliques et Cardiovasculaires (I2MC), CHU Rangueil, 1 Avenue Jean Poulhès, BP84225, 31432 Toulouse Cedex 4, France
| | - Patrice D Cani
- NeuroMicrobiota, European Associated Laboratory (EAL) INSERM/UCL, France; Université Catholique de Louvain (UCL), Louvain Drug Research Institute, LDRI, Metabolism and Nutrition Research Group, WELBIO (Walloon Excellence in Life sciences and BIOtechnology), Avenue E. Mounier, 73 B1.73.11, B-1200, Brussels, Belgium.
| | - Claude Knauf
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1220, Université Paul Sabatier, UPS, Institut de Recherche en Santé Digestive et Nutrition (IRSD), CHU Purpan, Place du Docteur Baylac, CS 60039, 31024 Toulouse Cedex 3, France; NeuroMicrobiota, European Associated Laboratory (EAL) INSERM/UCL, France.
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Zalecki M, Sienkiewicz W, Franke-Radowiecka A, Klimczuk M, Kaleczyc J. The Influence of Gastric Antral Ulcerations on the Expression of Galanin and GalR1, GalR2, GalR3 Receptors in the Pylorus with Regard to Gastric Intrinsic Innervation of the Pyloric Sphincter. PLoS One 2016; 11:e0155658. [PMID: 27175780 PMCID: PMC4866767 DOI: 10.1371/journal.pone.0155658] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/02/2016] [Indexed: 01/29/2023] Open
Abstract
Gastric antrum ulcerations are common disorders occurring in humans and animals. Such localization of ulcers disturbs the gastric emptying process, which is precisely controlled by the pylorus. Galanin (Gal) and its receptors are commonly accepted to participate in the regulation of inflammatory processes and neuronal plasticity. Their role in the regulation of gastrointestinal motility is also widely described. However, there is lack of data considering antral ulcerations in relation to changes in the expression of Gal and GalR1, GalR2, GalR3 receptors in the pyloric wall tissue and galaninergic intramural innervation of the pylorus. Two groups of pigs were used in the study: healthy gilts and gilts with experimentally induced antral ulcers. By double immunocytochemistry percentages of myenteric and submucosal neurons expressing Gal-immunoreactivity were determined in the pyloric wall tissue and in the population of gastric descending neurons supplying the pyloric sphincter (labelled by retrograde Fast Blue neuronal tracer). The percentage of Gal-immunoreactive neurons increased only in the myenteric plexus of the pyloric wall (from 16.14±2.06% in control to 25.5±2.07% in experimental animals), while no significant differences in other neuronal populations were observed between animals of both groups. Real-Time PCR revealed the increased expression of mRNA encoding Gal and GalR1 receptor in the pyloric wall tissue of the experimental animals, while the expression(s) of GalR2 and GalR3 were not significantly changed. The results obtained suggest the involvement of Gal, GalR1 and galaninergic pyloric myenteric neurons in the response of pyloric wall structures to antral ulcerations.
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Affiliation(s)
- Michal Zalecki
- Department of Animal Anatomy, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
- * E-mail:
| | - Waldemar Sienkiewicz
- Department of Animal Anatomy, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
| | - Amelia Franke-Radowiecka
- Department of Animal Anatomy, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
| | - Magdalena Klimczuk
- Department of Animal Anatomy, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
| | - Jerzy Kaleczyc
- Department of Animal Anatomy, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
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Neuronally released vasoactive intestinal polypeptide alters atrial electrophysiological properties and may promote atrial fibrillation. Heart Rhythm 2015; 12:1352-61. [PMID: 25748673 DOI: 10.1016/j.hrthm.2015.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Indexed: 11/22/2022]
Abstract
BACKGROUND Vagal hyperactivity promotes atrial fibrillation (AF), which has been almost exclusively attributed to acetylcholine. Vasoactive intestinal polypeptide (VIP) and acetylcholine are neurotransmitters co-released during vagal stimulation. Exogenous VIP has been shown to promote AF by shortening action potential duration (APD), increasing APD spatial heterogeneity, and causing intra-atrial conduction block. OBJECTIVE The purpose of this study was to investigate the effects of neuronally released VIP on atrial electrophysiologic properties during vagal stimulation. METHODS We used a specific VIP antagonist (H9935) to uncover the effects of endogenous VIP released during vagal stimulation in canine hearts. RESULTS H9935 significantly attenuated (1) the vagally induced shortening of atrial effective refractory period and widening of atrial vulnerability window during stimulation of cervical vagosympathetic trunks (VCNS) and (2) vagal effects on APD during stimulation through fat-pad ganglion plexus (VGPS). Atropine completely abolished these vagal effects during VCNS and VGPS. In contrast, VGPS-induced slowing of local conduction velocity was completely abolished by either VIP antagonist or atropine. In pacing-induced AF during VGPS, maximal dominant frequencies and their spatial gradients were reduced significantly by H9935 and, more pronouncedly, by atropine. Furthermore, VIP release in the atria during vagal stimulation was inhibited by atropine, which may account for the concealment of VIP effects with muscarinic blockade. CONCLUSION Neuronally released VIP contributes to vagal effects on atrial electrophysiologic properties and affects the pathophysiology of vagally induced AF. Neuronal release of VIP in the atria is inhibited by muscarinic blockade, a novel mechanism by which VIP effects are concealed by atropine during vagal stimulation.
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Koroleva SV, Nikolaeva AA, Ashmarin IP. Types of bioinformatic programs in the continuum of regulatory peptides and non-peptide mediators. Traits of interaction of dopamine and serotonin systems. NEUROCHEM J+ 2012. [DOI: 10.1134/s1819712412020031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Hansen L, Lampert S, Mineo H, Holst JJ. Neural regulation of glucagon-like peptide-1 secretion in pigs. Am J Physiol Endocrinol Metab 2004; 287:E939-47. [PMID: 15475512 DOI: 10.1152/ajpendo.00197.2004] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucagon-like peptide (GLP)-1 is secreted rapidly from the intestine postprandially. We therefore investigated its possible neural regulation. With the use of isolated perfused porcine ileum, GLP-1 secretion was measured in response to electrical stimulation of the mixed, perivascular nerve supply and infusions of neuroactive agents alone and in combination with different blocking agents. Electrical nerve stimulation inhibited GLP-1 secretion, an effect abolished by phentolamine. Norepinephrine inhibited secretion, and phentolamine abolished this effect. GLP-1 secretion was stimulated by isoproterenol (abolished by propranolol). Acetylcholine stimulated GLP-1 secretion, and atropine blocked this effect. Dimethylphenylpiperazine stimulated GLP-1 secretion. In chloralose-anesthetized pigs, however, electrical stimulation of the vagal trunks at the level of the diaphragm had no effect on GLP-1 or GLP-2 and weak effects on glucose-dependent insulinotropic peptide and somatostatin secretion, although this elicited a marked atropine-resistant release of the neuropeptide vasoactive intestinal polypeptide to the portal circulation. Thus GLP-1 secretion is inhibited by the sympathetic nerves to the gut and may be stimulated by intrinsic cholinergic nerves, whereas the extrinsic vagal supply has no effect.
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Affiliation(s)
- Lene Hansen
- Dept. of Medical Physiology, University of Copenhagen, the Panum Institute, Blegdamsvej 3, DK-2200 Copenhagen, Denmark
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Hansen L, Hartmann B, Bisgaard T, Mineo H, Jørgensen PN, Holst JJ. Somatostatin restrains the secretion of glucagon-like peptide-1 and -2 from isolated perfused porcine ileum. Am J Physiol Endocrinol Metab 2000; 278:E1010-8. [PMID: 10827002 DOI: 10.1152/ajpendo.2000.278.6.e1010] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Suspecting that paracrine inhibition might influence neuronal regulation of the endocrine L cells, we studied the role of somatostatin (SS) in the regulation of the secretion of the proglucagon-derived hormones glucagon-like peptide-1 and -2 (GLP-1 and GLP-2). This was examined using the isolated perfused porcine ileum stimulated with acetylcholine (ACh, 10(-6) M), neuromedin C (NC, 10(-8) M), and electrical nerve stimulation (NS) with or without alpha-adrenergic blockade (phentolamine 10(-5) M), and perfusion with a high-affinity monoclonal antibody against SS. ACh and NC significantly increased GLP secretion, whereas NS had little effect. SS immunoneutralization increased GLP secretion eight- to ninefold but had little influence on the GLP responses to ACh, NC, and NS. Basal SS secretion (mainly SS28) was unaffected by NS alone. Phentolamine + NS and NC abstract strongly stimulated release mainly of SS14, whereas ACh had little effect. Infused intravascularly, SS14 weakly and SS28 strongly inhibited GLP secretion. We conclude that GLP secretion is tonically inhibited by a local release of SS28 from epithelial paracrine cells, whereas SS14, supposedly derived from enteric neurons, only weakly influences GLP secretion.
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Affiliation(s)
- L Hansen
- Department of Medical Physiology, the Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark
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Erlwanger KH, Unmack MA, Grøndahl ML, Skadhauge E, Thorbøll JE. Effect of age on vasoactive intestinal polypeptide-induced short-circuit current in porcine jejunum. Comp Biochem Physiol A Mol Integr Physiol 1999; 124:29-33. [PMID: 10605064 DOI: 10.1016/s1095-6433(99)00077-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Vasoactive intestinal polypeptide is a transmitter at the neuroepithelial junction of the small intestine in cholera toxin-induced secretion. We investigated whether the secretory effect in vitro of vasoactive intestinal polypeptide in porcine jejunum was changed with age. Stripped tissue preparations from three age groups, neonatal (7-11 days), young (6-8 weeks) and adult (13-15 weeks) pigs, were mounted in Ussing chambers and short-circuited. Vasoactive intestinal polypeptide produced concentration dependent increases in short-circuit current in all three age groups with EC50 values (in nM) of 14.5 +/- 1.9, 16.2 +/- 2.0 and 147 +/- 0 in neonatal, young and adult pigs, respectively. The peak increases in short-circuit current in adult pigs were significantly decreased compared with the other two age groups. To evaluate the secretory capacity, theophylline was added to tissue preparations in which baseline short-circuit current again was established. Theophylline caused a significantly lesser increase in short-circuit current in adult pigs (25.4 +/- 2.0 microA.cm-2) than neonatal (57.1 +/- 3.6 microA.cm-2) and young pigs (63.1 +/- 2.9 microA.cm-2). In conclusion, vasoactive intestinal polypeptide showed a marked decrease in the secretory response with age in porcine jejunum, at least partly caused by a reduced secretory capacity of the enterocytes.
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Affiliation(s)
- K H Erlwanger
- Faculty of Veterinary Science, University of Zimbabwe, Harare
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Thorbøll JE, Bindslev N, Tindholdt TT, Schmidt P, Christensen P, Skadhauge E. Tachykinins mediate changes in ion transport in porcine jejunum through release of prostaglandins and neurotransmitters. REGULATORY PEPTIDES 1998; 77:105-11. [PMID: 9809803 DOI: 10.1016/s0167-0115(98)00106-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In the present study, we investigated the mediators involved in substance P (SP) and neurokinin A (NKA) induced ion transport. Stripped preparations of porcine jejunal tissue were mounted in Ussing-chambers and short-circuited. The cyclo-oxygenase inhibitor, piroxicam (10 microM) and the neuronal conduction blocker, tetrodotoxin (TTX) (0.1 microM) both significantly decreased the SP (0.1 microM) (66% and 36%, respectively) and NKA (1 microM) (64% and 31%, respectively) induced increase in short-circuit current (SCC). Pretreatment with both piroxicam and TTX totally abolished the SP and NKA response. SP (0.1 microM) caused a significant release of prostaglandin E2 (PGE2), whereas the release of PGE2 induced by NKA was not significant. Experiments were performed to clarify if vasoactive intestinal polypeptide (VIP) was mediating SP or NKA responses. VIP caused a TTX-insensitive and a concentration-dependent increase in SCC. Two VIP antagonists did not change the response to VIP (10 nM and 0.1 microM). Thus, these antagonists could not be used to further elucidate the role of VIP. We were unable to measure a significant release of VIP after SP or NKA treatment. These results indicate, that SP and NKA regulate ion transport in porcine jejunum, entirely through the release of prostaglandins and enteric neurotransmitters.
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Affiliation(s)
- J E Thorbøll
- Department of Anatomy and Physiology, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
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Pooga M, Juréus A, Razaei K, Hasanvan H, Saar K, Kask K, Kjellén P, Land T, Halonen J, Mäeorg U, Uri A, Solyom S, Bartfai T, Langel U. Novel galanin receptor ligands. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 1998; 51:65-74. [PMID: 9495593 DOI: 10.1111/j.1399-3011.1998.tb00418.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Galanin is a neuroendocrine peptide which is 29/30 amino acids in length and is recognised by G-protein-coupled central nervous system receptors via its N-terminus. We synthesised several galanin receptor ligands and fragments around C-terminal extensions of galanin(1-13) to yield chimeric peptides with C-terminals corresponding to bioactive peptides like bradykinin(2-9), mastoparan, neuropeptide Y(25-36) or substance P(5-11), respectively. We also synthesised short galanin analogs in which galanin(1-13) was C-terminally elongated with Lys14; different pharmacologically active small molecules were then attached to the epsilon-amino group of Lys14. Several cysteine-substituted linear and ring closed analogs of galanin(1-9) and galanin(1-16) were also synthesised. The equilibrium binding constants for these peptides at hypothalamic galanin receptors were determined and found in the subnanomolar to micromolar range. The large number of peptides and their binding affinities presented here permit structure-activity relationship analysis of peptide-type ligands to galanin receptors.
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Affiliation(s)
- M Pooga
- Department of Neurochemistry and Neurotoxicology, Stockholm University, Sweden
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Abstract
The involvement of the tachykinins in extrinsic nervous control of motility was studied in isolated, vascularly perfused, porcine ileal segments. Substance P and neurokinin A (10(-8) M) stimulated motility, and nonpeptide NK1 and NK2 receptor antagonists (10(-6) M) abolished this. Electrical stimulation of the mixed extrinsic nerves (8 Hz) had no effect alone or with atropine (10(-6) M) or phentolamine (10(-5) M), but increased motility during coinfusion of both blockers. This effect was abolished by hexamethonium (3 x 10(-5) M), and was reduced by over 80% by the NK1 receptor antagonist. As previously shown, substance P and neurokinin A were released during nerve stimulation, only during blockade of alpha-adrenergic and muscarinic receptors, and the release was abolished by hexamethonium. Capsaicin infusions (10(-5) M) increased substance P and neurokinin A release, and weakly stimulated small intestinal motility, but this was not inhibited by the tachykinin antagonists. Our results suggest that intrinsic tachykinin-producing neurons, controlled by extrinsic, nicotinic, excitatory neural pathways, and extrinsic adrenergic, inhibitory pathways, participate in the regulation of small intestinal motility.
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Affiliation(s)
- P T Schmidt
- Institute of Medical Physiology, Panum Institute, National University Hospital, University of Copenhagen, Denmark
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Stadelmann AM, Telford GL, Appel DA, Walgenbach-Telford S, Hopp K, Meier DA, Koch TR. Expression of mRNA for vasoactive intestinal peptide in rat small intestine. Mol Cell Endocrinol 1996; 116:31-7. [PMID: 8822262 DOI: 10.1016/0303-7207(95)03693-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Transplantation of small intestine is a neural model that permits studies of expression of the neuropeptide, vasoactive intestinal peptide, following extrinsic denervation, transection of intrinsic neural pathways, and an ischemic interval. Tissue levels of vasoactive intestinal peptide were examined at 3 months in ileum from a sham operation, in ileum after resection of proximal small intestine, in ileum after resection of proximal small intestine and extrinsic denervation, in ileum after resection of proximal small intestine and 30 min of ischemia, and in ileum obtained 3 months after ileal isografting in Lewis-to-Lewis combinations. Vasoactive intestinal peptide levels were increased in transplanted rat ileum, resection controls, denervation controls, and ischemic controls compared to sham-operated ileum (pANOVA < 0.01). The increased levels of this peptide were highest in denervation controls and lowest in ischemic controls. Northern blot analysis using rat vasoactive intestinal peptide cDNA identified a single 1.7-kb transcript in normal and transplanted rat ileum. The density of vasoactive intestinal peptide transcripts was increased in transplanted ileum (8450 +/- 540) compared to normal ileum (5790 +/- 620) (P < 0.01), and the ratio of this transcript to glyceraldehyde-3-phosphate dehydrogenase density units was also increased in transplanted ileum (0.81 +/- 0.08) compared to normal ileum (0.40 +/- 0.07; P < 0.01). Enhanced transcriptional regulation was the likely mechanism for increased tissue vasoactive intestinal peptide. The increased tissue levels appeared to be a response to extrinsic denervation and transection of intrinsic neural pathways, while an ischemic interval appeared to decrease tissue levels of the peptide.
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Affiliation(s)
- A M Stadelmann
- Department of Medicine, Zablocki VA Medical Center, Milwaukee 53295, USA
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Kimura H, Ito S, Ohta T, Asano T, Nakazato Y. Vasoactive intestinal peptide released by acetylcholine in the dog ileum. JOURNAL OF THE AUTONOMIC NERVOUS SYSTEM 1994; 48:167-74. [PMID: 8089398 DOI: 10.1016/0165-1838(94)90032-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Release of vasoactive intestinal peptide (VIP) in response to acetylcholine (ACh) was characterized in the dog ileum using cholinergic antagonists. In blood-perfused ileum, ACh (2-200 nmol/min) produced a dose-dependent increase in venous VIP output, which was slightly reduced by hexamethonium (10 nmol/min) and blocked by hexamethonium and atropine (10 nmol/min) in combination. In isolated ileal tissues containing the submucous or myenteric plexus, excess KCl (75 mM), veratridine (0.1 mM) and ACh (0.1 mM) evoked the release of VIP. ACh-induced VIP output was decreased slightly by hexamethonium (0.1 mM), and blocked by atropine (0.1 mM) or pirenzepine (0.1 mM). Dimethylphenylpiperazinium (0.1 mM) also caused a small increase in VIP output sensitive to hexamethonium in the ileal tissues containing either the submucous or myenteric plexus. It is concluded that ACh evokes the release of VIP from VIP-containing neurons of the submucous and myenteric plexuses in the dog ileum mainly through the activation of M1 muscarinic receptors.
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Affiliation(s)
- H Kimura
- Department of Pharmacology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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14
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Abstract
Pancreastatin, a 49-amino acid peptide with a COOH-terminal glycine amide, was originally isolated from porcine pancreas, but pancreastatin immunoreactivity has been found in several neuroendocrine tissues. There are strong indications that pancreastatin is derived from chromogranin A, since the amino acid sequence 240-288 in porcine chromogranin A corresponds to pancreastatin flanked by typical signals for proteolytic processing. We have studied the effect of electric stimulation of the nervous supply to perfused porcine pancreas, antrum, nonantral stomach, and small intestine on the release of immunoreactive pancreastatin, and we characterized the molecular nature of the secreted immunoreactivity by using a radioimmunoassay specific for the COOH-terminal glycine amide of porcine pancreastatin in combination with chromatography. In all tissues nerve stimulation significantly increased the release of immunoreactive pancreastatin. The secreted immunoreactive pancreastatin was heterogeneous, consisting of pancreastatin itself, a COOH-terminal pancreastatin fragment, and NH2-terminally extended pancreastatin forms. Pancreastatin predominated in the perfusate from pancreas and antrum, whereas mainly NH2-terminally extended molecular forms were secreted from the antrectomized stomach and small intestine. The different molecular forms of pancreastatin were secreted from the perfused organs in the same molar ratio as they occur in extracts of the corresponding tissues. Thus, pancreastatin and other chromogranin A-derived peptides in organ-specific proportions regularly accompany the secretion of the peptide hormones from the gastrointestinal tissues on appropriate stimulation.
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Affiliation(s)
- T D Jensen
- Dept. of Clinical Chemistry, Bispebjerg Hospital, Denmark
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15
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Schmidt P, Rasmussen TN, Holst JJ. Release of immunoreactive somatostatin, vasoactive intestinal polypeptide (VIP), and galanin during propulsive complexes in isolated pig ileum. Peptides 1993; 14:215-20. [PMID: 7683399 DOI: 10.1016/0196-9781(93)90032-c] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We studied the release of immunoreactive somatostatin, VIP, and galanin during net aboral propulsive complexes (NAP) in isolated, perfused, 80-cm segments of porcine ileum. Net aboral propulsive complexes were induced by controlled infusion of liquid (perfusion medium, 3.5 ml/min) into the proximal opening of the ileum segment. In response to liquid infusion, the ileum segments generated propulsive complexes rapidly propagating along the entire segment in the aboral direction, resulting in emptying of the luminal contents. The NAPs occurred with an average interval of 7 minutes. The concentrations of galanin, somatostatin, and VIP in the venous effluent, which in control experiments without luminal infusion did not change, increased significantly (by 63.6 +/- 23.7%, 43.8 +/- 31.8%, and 38.8 +/- 14.6%, respectively) during NAPs and emptying. Atropine (10(-6) mol/l) and hexamethonium (10(-5) mol/l) abolished both NAP generation and peptide responses. It is concluded that the enteric neuropeptides, somatostatin, VIP, and galanin, all of which have pronounced intestinal motor effects, may participate in the generation of net aboral propulsive complexes in the ileum of the pig, possibly mainly in descending relaxation.
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Affiliation(s)
- P Schmidt
- Department of Medical Physiology C, Panum Institute, Copenhagen, Denmark
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