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McIlwrath SL, Westlund KN. Pharmacological attenuation of chronic alcoholic pancreatitis induced hypersensitivity in rats. World J Gastroenterol 2015; 21:836-53. [PMID: 25624717 PMCID: PMC4299336 DOI: 10.3748/wjg.v21.i3.836] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 08/16/2014] [Accepted: 09/29/2014] [Indexed: 02/06/2023] Open
Abstract
AIM To characterize an alcohol and high fat diet induced chronic pancreatitis rat model that mimics poor human dietary choices. METHODS Experimental rats were fed a modified Lieber-DeCarli alcohol (6%) and high-fat (65%) diet (AHF) for 10 wk while control animals received a regular rodent chow diet. Weekly behavioral tests determined mechanical and heat sensitivity. In week 10 a fasting glucose tolerance test was performed, measuring blood glucose levels before and after a 2 g/kg bodyweight intraperitoneal (i.p.) injection of glucose. Post mortem histological analysis was performed by staining pancreas and liver tissue sections with hematoxylin and eosin. Pancreas sections were also stained with Sirius red and fast green to quantify collagen content. Insulin-expressing cells were identified immunohistochemically in separate sections. Tissue staining density was quantified using Image J software. After mechanical and heat sensitivity became stable (weeks 6-10) in the AHF-fed animals, three different drugs were tested for their efficacy in attenuating pancreatitis associated hypersensitivity: a Group II metabotropic glutamate receptor specific agonist (2R,4R)-4-Aminopyrrolidine-2,4-dicarboxylate (APDC, 3 mg/kg, ip; Tocris, Bristol, United Kingdom), nociceptin (20, 60, 200 nmol/kg, ip; Tocris), and morphine sulfate (3 mg/kg, μ-opioid receptor agonist; Baxter Healthcare, Deerfield, IL, United States). RESULTS Histological analysis of pancreas and liver determined that unlike control rats, AHF fed animals had pancreatic fibrosis, acinar and beta cell atrophy, with steatosis in both organs. Fat vacuolization was significantly increased in AHF fed rats (6.4% ± 1.1% in controls vs 23.8% ± 4.2%, P < 0.05). Rats fed the AHF diet had reduced fasting glucose tolerance in week 10 when peak blood glucose levels reached significantly higher concentrations than controls (127.4 ± 9.2 mg/dL in controls vs 161.0 ± 8.6 mg/dL, P < 0.05). This concurred with a 3.5 fold higher incidence of single and small 2-10 cell insulin-positive cell clusters (P < 0.05). Insulin expressing islet of Langerhans cells appeared hypertrophied while islet number and area measurements were not different from controls. Weekly behavioral tests determined that mechanical and heat sensitivities were significantly increased by 4 wk on AHF diet compared to controls. Hypersensitivity was attenuated with efficacy similar to morphine with single dose treatment of either metabotropic glutamate receptor 2/3 agonist APDC, or nociceptin, the endogenous ligand for opioid-receptor-like 1 receptor. CONCLUSION The AHF diet induces a chronic alcoholic pancreatitis in rats with measurable features resembling clinical patients with chronic pancreatitis and type 3c diabetes mellitus.
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MESH Headings
- Analgesics/pharmacology
- Analgesics, Opioid/pharmacology
- Animals
- Behavior, Animal/drug effects
- Blood Glucose/drug effects
- Blood Glucose/metabolism
- Diabetes Mellitus/etiology
- Diet, High-Fat
- Disease Models, Animal
- Ethanol
- Excitatory Amino Acid Agonists/pharmacology
- Humans
- Hyperalgesia/etiology
- Hyperalgesia/metabolism
- Hyperalgesia/physiopathology
- Hyperalgesia/prevention & control
- Liver/drug effects
- Liver/metabolism
- Liver/pathology
- Male
- Morphine/pharmacology
- Nociception/drug effects
- Opioid Peptides/metabolism
- Pain Threshold/drug effects
- Pancreas/drug effects
- Pancreas/metabolism
- Pancreas/pathology
- Pancreatitis, Alcoholic/drug therapy
- Pancreatitis, Alcoholic/etiology
- Pancreatitis, Alcoholic/metabolism
- Pancreatitis, Alcoholic/physiopathology
- Proline/analogs & derivatives
- Proline/pharmacology
- Rats, Inbred F344
- Receptors, Metabotropic Glutamate/agonists
- Receptors, Metabotropic Glutamate/metabolism
- Time Factors
- Visceral Pain/etiology
- Visceral Pain/metabolism
- Visceral Pain/physiopathology
- Visceral Pain/prevention & control
- Nociceptin
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Stamer U, Book M, Comos C, Zhang L, Nauck F, Stüber F. Expression of the nociceptin precursor and nociceptin receptor is modulated in cancer and septic patients. Br J Anaesth 2011; 106:566-72. [DOI: 10.1093/bja/aer007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Joseph T, Lee TL, Li C, Siau C, Nishiuchi Y, Kimura T, Tachibana S. Levels of neuropeptides nocistatin, nociceptin/orphanin FQ and their precursor protein in a rat neuropathic pain model. Peptides 2007; 28:1433-40. [PMID: 17583384 DOI: 10.1016/j.peptides.2007.05.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Revised: 05/15/2007] [Accepted: 05/16/2007] [Indexed: 11/28/2022]
Abstract
Neuropeptides nociceptin/orphanin FQ (N/OFQ) and nocistatin (NST) are related to pain modulation. The amounts of these peptides and their precursor protein, prepronociceptin (ppN/OFQ) in the brain, spinal cord and serum samples of rats with partial sciatic nerve ligation (PSNL) were compared with those in naïve rats using radioimmunoassay (RIA). There was a significant rise in the levels of ppN/OFQ, N/OFQ and NST in the brains of PSNL rats. Their spinal cords showed significantly increased ppN/OFQ and NST levels but no change in N/OFQ levels. The PSNL rats also had increased serum NST (statistically significant) and N/OFQ (statistically insignificant) with decreased ppN/OFQ suggesting important roles of these peptides in neuropathic pain mechanism.
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Affiliation(s)
- Tessy Joseph
- Department of Anaesthesia, Yong Loo Lin School of Medicine, National University of Singapore, 5 Lower Kent Ridge Road, Singapore 119074, Singapore
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Chen Y, Sommer C. Nociceptin and its receptor in rat dorsal root ganglion neurons in neuropathic and inflammatory pain models: implications on pain processing. J Peripher Nerv Syst 2006; 11:232-40. [PMID: 16930285 DOI: 10.1111/j.1529-8027.2006.0093.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Nociceptin (NC), by activating its receptor, the opioid receptor-like 1 (ORL1) receptor, exerts an effect on a number of functions in the nervous system including locomotion, learning and memory, and processing of pain signals. Data on the expression of NC and ORL1 receptor in dorsal root ganglion (DRG) neurons and on its modulation after nerve injury and inflammation are controversial. We therefore sought to investigate the immunoreactivity (IR) of NC and ORL1 receptor in DRG neurons in two pain models, a pure neuropathic pain model, namely partial sciatic nerve transection (PST), and an inflammatory pain model, complete Freund's adjuvant (CFA) injection into the hindpaw. In intact DRG neurons, both NC and ORL1 receptor IR were present in mainly small- and medium-sized neurons, NC IR in 31% and ORL1 receptor IR in 33% of all neuronal profiles. Both NC and ORL1 receptor IR were upregulated 7 days after nerve injury (to 56 and 55%) and inflammation (to 53 and 48%), respectively. Activating transcription factor 3 (ATF3), a neuronal marker of nerve injury, was induced in DRG neurons 7 and 14 days after PST and 7 days after CFA injection. Double labeling with ATF3 revealed expression of NC and ORL1 receptor in intact as well as in injured primary afferent neurons. Thus, NC and the ORL1 receptor may be involved in the modulation of neuropathic and inflammatory pain at the level of the primary afferent neuron.
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Affiliation(s)
- Yong Chen
- Department of Neurology, Julius-Maximilians-University, Würzburg, Germany.
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Valencia-de Ita S, Lawand NB, Lin Q, Castañeda-Hernandez G, Willis WD. Role of the Na+-K+-2Cl- cotransporter in the development of capsaicin-induced neurogenic inflammation. J Neurophysiol 2006; 95:3553-61. [PMID: 16709721 DOI: 10.1152/jn.01091.2005] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recent behavioral and electrophysiological studies have attributed an important role to dorsal root reflexes (DRRs) in the initiation and development of neurogenic inflammation produced by intradermal capsaicin (CAP). The DRRs can occur in peptidergic fibers, resulting in peripheral release of neuromediators that produce vasodilation, plasma extravasation and subsequently hyperalgesia and allodynia. In this study, we have evaluated the effect of spinal administration of bumetanide (a blocker of the Na+-K+-2Cl- cotransporter, NKCC) on DRR activity, changes in cutaneous blood flow (vasodilation), hindpaw edema, mechanical allodynia, and hyperalgesia induced by intradermal injection of 1% CAP in Sprague-Dawley rats. Vasodilation was monitored using laser Doppler flowmetry, neurogenic edema was evaluated by measurements of hindpaw volume, and secondary mechanical allodynia and hyperalesia were tested using von Frey filaments (10 and 200 mN) applied to the plantar surface of the paw. Changes in the blood flow were blocked significantly by intrathecal bumetanide at 10 and 100 microM in both pre- and posttreatment studies. Spinal bumetanide at 10 and 100 microM blocked neurogenic edema when it was administered before CAP injection, but only bumetanide at 100 microM administered after CAP injection reduced the paw edema significantly. Furthermore, the administration of bumetanide onto the spinal cord reduced the increment in DRR activity produced by CAP. Finally, both secondary mechanical allodynia and hyperalesia were reduced by bumetanide at 1, 10, and 100 microM. Taken together these results suggest that NKCC is involved in the increases in DRR activity, neurogenic inflammation and hyperalgesia and allodynia induced by intradermal CAP.
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Affiliation(s)
- Sandra Valencia-de Ita
- Seccion Externa de Farmacologia, Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, Mexico, DF Mexico
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Okuda-Ashitaka E, Minami T, Matsumura S, Takeshima H, Reinscheid RK, Civelli O, Ito S. The opioid peptide nociceptin/orphanin FQ mediates prostaglandin E2-induced allodynia, tactile pain associated with nerve injury. Eur J Neurosci 2006; 23:995-1004. [PMID: 16519664 DOI: 10.1111/j.1460-9568.2006.04623.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pain often outlasts its usefulness as warning and aid in wound healing, and becomes chronic and intractable after tissue damage and nerve injury. Many molecules have been implicated as mediators and modulators in persistent pain such as hyperalgesia and tactile pain (allodynia). We previously showed that prostaglandin (PG) E(2), PGF(2alpha) or the neuropeptide nociceptin, also called orphanin FQ (N/OFQ) administered intrathecally (i.t.) produced allodynia in conscious mice. In the present study, we examined the relationship of pain responses between PGs and N/OFQ using the N/OFQ receptor (NOP) antagonist, N-(4-amino-2-methylquinolin-6-yl)-2-(4-ethylphenoxy-methyl)benzamide monohydrochloride (JTC-801), and in mice lacking the N/OFQ prepropeptide (ppN/OFQ(-/-)) and the NOP receptor (NOP(-/-)). JTC-801 dose-dependently blocked the N/OFQ- and PGE(2)-induced allodynia, but not the PGF(2alpha)-induced one. Neither N/OFQ nor PGE(2) induced allodynia in NOP(-/-) mice. By contrast, the N/OFQ-induced allodynia was not affected by inhibition of PG production by a 60-min pretreatment with the non-steroidal anti-inflammatory drug, indomethacin. Among PGE receptor (EP) subtype-selective agonists, the EP4 agonist, AE1-329, markedly stimulated the release of N/OFQ from spinal slices and induced allodynia. AE1-329 also increased nitric oxide production in spinal slices using fluorescent nitric oxide detection, which was blocked by pretreatment with JTC-801. Conversely, PGE(2)-induced allodynia was not observed in ppN/OFQ(-/-) mice. N/OFQ immunoreactive puncta were colocalized with EP4. Taken together, these results demonstrate that PGE(2) induced allodynia by stimulation of N/OFQ release in the spinal cord via EP4 receptor subtypes.
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Affiliation(s)
- Emiko Okuda-Ashitaka
- Department of Medical Chemistry, Kansai Medical University, 10-15 Fumizono, Moriguchi 570-8506, Japan
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7
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D'Agostino B, Marrocco G, De Nardo M, Calò G, Guerrini R, Gallelli L, Advenier C, Rossi F. Activation of the nociceptin/orphanin FQ receptor reduces bronchoconstriction and microvascular leakage in a rabbit model of gastroesophageal reflux. Br J Pharmacol 2005; 144:813-20. [PMID: 15685213 PMCID: PMC1576063 DOI: 10.1038/sj.bjp.0706066] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2004] [Revised: 09/22/2004] [Accepted: 10/20/2004] [Indexed: 12/12/2022] Open
Abstract
1. Nociceptin/orphanin FQ (N/OFQ) is the endogenous peptide ligand for a specific G-protein coupled receptor, the N/OFQ peptide receptor (NOP). The N/OFQ-NOP receptor system has been reported to play an important role in pain, anxiety and appetite regulation. In airways, N/OFQ was found to inhibit the release of tachykinins and the bronchoconstriction and cough provoked by capsaicin. 2. Here we evaluated the effects of NOP receptor activation in bronchoconstriction and airway microvascular leakage induced by intraesophageal (i.oe.) hydrochloric acid (HCl) instillation in rabbits. We also tested the effects of NOP receptor activation in SP-induced plasma extravasation and bronchoconstriction. 3. In anesthetized New Zealand rabbits bronchopulmonary function (total lung resistance (R(L)) and dynamic compliance (C(dyn))) and airway microvascular leakage (extravasation of Evans blue dye) were evaluated. 4. Infusion of i.oe. HCl (1 N) led to a significant increase in bronchoconstriction and plasma extravasation in the main bronchi and trachea of rabbits pretreated with propranolol, atropine and phosphoramidon. 5. Bronchoconstriction and airway microvascular leakage were inhibited by N/OFQ (3-30 microg kg(-1) i.v.) in a dose-dependent manner. The NOP receptor agonist [Arg14,Lys15]N/OFQ mimicked the inhibitory effect of N/OFQ, being 10-fold more potent, UFP-101, a peptide selective NOP receptor antagonist, blocked the inhibitory effects of both agonists. 6. Under the same experimental conditions, N/OFQ and [Arg14,Lys15]N/OFQ did not counteract the bronchoconstriction and airway microvascular leakage induced by substance P. 7. These results suggest that bronchoconstriction and airway plasma extravasation induced by i.oe. HCl instillation are inhibited by activation of prejunctional NOP receptors.
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Affiliation(s)
- Bruno D'Agostino
- Department of Experimental Medicine-Section of Pharmacology, Faculty of Medicine and Surgery, 2nd University of Naples, via Constantinopoli 16, 80138 Naples, Italy.
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Sakurada S, Watanabe H, Mizoguchi H, Yonezawa A, Orito T, Katsuyama S, Kuramasu A, Sakurada C, Yanai K, Sakurada T. Involvement of the histaminergic system in the nociceptin-induced pain-related behaviors in the mouse spinal cord. Pain 2004; 112:171-82. [PMID: 15494198 DOI: 10.1016/j.pain.2004.08.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2003] [Revised: 08/03/2004] [Accepted: 08/23/2004] [Indexed: 11/22/2022]
Abstract
Intrathecal (i.t.) injection of nociceptin elicited a behavioral response mainly consisting of biting and licking, which were eliminated by the i.t. co-administration of opioid receptor-like-1 (ORL-1) receptor antagonists. The behavioral response induced by nociceptin was characteristically similar to that by i.t.-administered histamine, and was attenuated by i.t. co-administration of the H1 receptor antagonists, but not by the H2 receptor antagonists, whereas the H3 receptor antagonist promoted the nociceptin-induced behavior. H1 receptor knockout (H1R-KO) mice did not show the nociceptin-induced nociceptive behavior, which was observed in wild-type mice. Pretreatment with a histamine antiserum or a histidine decarboxylase inhibitor resulted in a significant reduction of the response to nociceptin. The previous studies showed that NK1 receptor antagonists and a novel substance P (SP)-specific antagonist given i.t. could reduce the behavioral response to nociceptin and histamine. On the other hand, the nociceptive response induced by nociceptin, but not histamine, was completely attenuated by the i.t. co-administration of agonists for GABAA and GABAB receptors. In contrast, the antagonists for GABAA and GABAB receptors injected i.t. showed same nociceptive response with nociceptin and histamine, and their nociceptive responses were significantly blocked by the i.t. co-administration of the H1 receptor antagonists, but not H2 receptor antagonists or ORL-1 receptor antagonists. The present results suggest that the activation of the ORL-1 receptor by nociceptin may induce the disinhibition of histaminergic neuron and enhance the release of histamine, which subsequently acts on the H1 receptor located on the SP-containing neurons to produce the spinal cord-mediated nociceptive response.
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Affiliation(s)
- Shinobu Sakurada
- Department of Physiology and Anatomy, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan.
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Rouget C, Cui YY, D'Agostino B, Faisy C, Naline E, Bardou M, Advenier C. Nociceptin inhibits airway microvascular leakage induced by HCl intra-oesophageal instillation. Br J Pharmacol 2004; 141:1077-83. [PMID: 14993101 PMCID: PMC1574276 DOI: 10.1038/sj.bjp.0705704] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2003] [Revised: 01/13/2004] [Accepted: 01/19/2004] [Indexed: 01/16/2023] Open
Abstract
1. Gastro-oesophageal acid reflux may cause airway responses such as cough, bronchoconstriction and inflammation in asthmatic patients. Our previous results suggest that microvascular leakage induced, in the guinea-pig airways, by intra-oesophageal hydrochloric acid (HCl) infusion was mainly dependent on the release of tachykinins. Nociceptin, an endogenous ligand of the opioid receptor NOP, has been shown to inhibit bronchoconstriction and cough in guinea-pig or cat by inhibiting tachykinin release. 2. The purpose of this study was to investigate the effects of nociceptin on the intra-oesophageal HCl-induced airway microvascular leakage evaluated by Evans blue dye extravasation measurement in anaesthetised guinea-pigs pretreated with propranolol, atropine and phosphoramidon. 3. Infusion of intra-oesophageal HCl led to a significant increase in plasma extravasation in the main bronchi and trachea. This increase was abolished when animals underwent a bilateral vagotomy. 4. Airway microvascular leakage was inhibited by nociceptin (3-30 microg x kg(-1) i.v.) in a dose-dependent manner (maximal inhibition at the dose of 30 microg x kg(-1): 19.76+/-1.13 vs 90.92+/-14.00 ng x mg(-1) tissue for nociceptin and HCl infusion, respectively, in the main bronchi, P<0.01). The NOP receptor agonist [Arg(14),Lys(15)]N/OFQ mimicked the inhibitory effect of nociceptin, but at a 10-fold lower dose (3 microg x kg(-1) i.v). The NOP receptor antagonist J-113397 had no effect on plasma protein extravasation by itself, but was able to block the inhibitory effect of nociceptin. 5. Morphine (1 mg x kg(-1)) had a similar inhibitory effect as that of nociceptin. Naloxone pretreatment abolished the effect of morphine, but was enable to block the inhibitory effect of nociceptin. 6. Under similar conditions, nociceptin, in the previous range of concentration, was unable to counteract the airway microvascular leakage induced by substance P (SP). 7. These results suggest that airway plasma extravasation induced by intra-oesophageal HCl instillation might be inhibited by specific stimulation of the NOP receptor with nociceptin. Nociceptin is likely to act at a pre-junctional level, by inhibiting tachykinin release, since it was unable to prevent SP-induced airway plasma extravasation.
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Affiliation(s)
- Céline Rouget
- UPRES EA220 – Pharmacology, University of Versailles and UFR Biomédicale des Saints Pères, 45 rue des Saints Pères, F-75006 Paris, France
| | - Yong Yao Cui
- UPRES EA220 – Pharmacology, University of Versailles and UFR Biomédicale des Saints Pères, 45 rue des Saints Pères, F-75006 Paris, France
| | - Bruno D'Agostino
- Department of Experimental Medicine – Section of Pharmacology, Faculty of Medicine and Surgery, 2nd University of Naples, Via Constantinopoli 16, 80138 Naples, Italy
| | - Christophe Faisy
- UPRES EA220 – Pharmacology, University of Versailles and UFR Biomédicale des Saints Pères, 45 rue des Saints Pères, F-75006 Paris, France
| | - Emmanuel Naline
- UPRES EA220 – Pharmacology, University of Versailles and UFR Biomédicale des Saints Pères, 45 rue des Saints Pères, F-75006 Paris, France
| | - Marc Bardou
- UPRES EA220 – Pharmacology, University of Versailles and UFR Biomédicale des Saints Pères, 45 rue des Saints Pères, F-75006 Paris, France
- Clinical Pharmacology Unit, LPPCE, Faculty of Medicine, 7 bd Jeanne d'Arc, BP 87900, 21079 Dijon Cedex, France
| | - Charles Advenier
- UPRES EA220 – Pharmacology, University of Versailles and UFR Biomédicale des Saints Pères, 45 rue des Saints Pères, F-75006 Paris, France
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Abstract
This paper is the twenty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2002 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, USA.
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Meunier JC. Utilizing functional genomics to identify new pain treatments : the example of nociceptin. AMERICAN JOURNAL OF PHARMACOGENOMICS : GENOMICS-RELATED RESEARCH IN DRUG DEVELOPMENT AND CLINICAL PRACTICE 2003; 3:117-30. [PMID: 12749729 DOI: 10.2165/00129785-200303020-00005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nociceptin/orphanin FQ (noc/oFQ) is the first novel bioactive substance to have been discovered by the implementation of a functional genomics/reverse pharmacology approach. The neuropeptide was indeed identified in brain extracts as the natural ligand of a previously cloned orphan G protein-coupled receptor, the opioid receptor-like 1 (ORL1) receptor. Since its discovery in 1995, noc/oFQ has been the subject of intensive study to establish its role in normal brain function and its possible involvement in neurophysiopathology. Although the neuropeptide, an inhibitor of neuronal activity, has been found to have a wide spectrum of pharmacological effects in vivo, none has been as intensively investigated as its action on nociception and nociceptive processing. There is now substantial evidence that noc/oFQ has a modulatory role in nociception. However, dependent on the dose and site of injection, and possibly the animal's genetic background and even psychological status, the peptide has been variously reported to cause allodynia, hyperalgesia, analgesia, and even pain, in rodents. Overall, noc/oFQ tends to facilitate pain when administered supraspinally, and to inhibit it when administered spinally. These opposing effects beg the obvious, yet still unanswered, question as to what would be the net effect on nociception of an ORL1 receptor ligand, agonist or antagonist, able to target supraspinal and spinal sites simultaneously. Owing to the research effort of several drug companies, such ligands, i.e. nonpeptidic, brain-penetrating agonists and antagonists, have recently been produced whose systematic screening in animal models of acute and inflammatory pain may help validate the ORL1 receptor as the target for novel, non-opioid analgesics.
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Affiliation(s)
- Jean-Claude Meunier
- Institute of Pharmacology and Structural Biology, National Centre for Scientific Research, Toulouse, France.
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