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Soares-Santos RR, Machado DP, Romero TL, Duarte IDG. Nitric oxide and potassium channels but not opioid and cannabinoid receptors mediate tramadol-induced peripheral antinociception in rat model of paw pressure withdrawal. Can J Physiol Pharmacol 2024; 102:218-227. [PMID: 37976474 DOI: 10.1139/cjpp-2023-0314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Tramadol, an analgesic classified as an "atypical opioid", exhibits both opioid and non-opioid mechanisms of action. This study aimed to explore these mechanisms, specifically the opioid-, cannabinoid-, nitric oxide-, and potassium channel-based mechanisms, which contribute to the peripheral antinociception effect of tramadol, in an experimental rat model. The nociceptive threshold was determined using paw pressure withdrawal. To examine the mechanisms of action, several substances were administered intraplantarly: naloxone, a non-selective opioid antagonist (50 µg/paw); AM251 (80 µg/paw) and AM630 (100 µg/paw) as the selective antagonists for types 1 and 2 cannabinoid receptors, respectively; nitric oxide synthase inhibitors L-NOArg, L-NIO, L-NPA, and L-NIL (24 µg/paw); and the enzyme inhibitors of guanylatocyclase and phosphodiesterase of cGMP, ODQ, and zaprinast. Additionally, potassium channel blockers glibenclamide, tetraethylammonium, dequalinium, and paxillin were used. The results showed that opioid and cannabinoid receptor antagonists did not reverse tramadol's effects. L-NOarg, L-NIO, and L-NPA partially reversed antinociception, while ODQ completely reversed, and zaprinast enhanced tramadol's antinociception effect. Notably, glibenclamide blocked tramadol's antinociception in a dose-dependent manner. These findings suggest that tramadol's peripheral antinociception effect is likely mediated by the nitrergic pathway and sensitive ATP potassium channels, rather than the opioid and cannabinoid pathways.
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Affiliation(s)
- Raquel R Soares-Santos
- Department of Pharmacology, Federal University of Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Daniel P Machado
- Department of Pharmacology, Federal University of Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Thiago L Romero
- Department of Pharmacology, Federal University of Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Igor D G Duarte
- Department of Pharmacology, Federal University of Minas Gerais (UFMG), Belo Horizonte, Brazil
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Schmidt H, Böttcher A, Gross T, Schmidtko A. cGMP signalling in dorsal root ganglia and the spinal cord: Various functions in development and adulthood. Br J Pharmacol 2021; 179:2361-2377. [PMID: 33939841 DOI: 10.1111/bph.15514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 03/12/2021] [Accepted: 03/31/2021] [Indexed: 12/27/2022] Open
Abstract
Cyclic GMP (cGMP) is a second messenger that regulates numerous physiological and pathophysiological processes. In recent years, more and more studies have uncovered multiple roles of cGMP signalling pathways in the somatosensory system. Accumulating evidence suggests that cGMP regulates different cellular processes from embryonic development through to adulthood. During embryonic development, a cGMP-dependent signalling cascade in the trunk sensory system is essential for axon bifurcation, a specific form of branching of somatosensory axons. In adulthood, various cGMP signalling pathways in distinct cell populations of sensory neurons and dorsal horn neurons in the spinal cord play an important role in the processing of pain and itch. Some of the involved enzymes might serve as a target for future therapies. In this review, we summarise the knowledge regarding cGMP-dependent signalling pathways in dorsal root ganglia and the spinal cord during embryonic development and adulthood, and the potential of targeting these pathways.
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Affiliation(s)
- Hannes Schmidt
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Alexandra Böttcher
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Tilman Gross
- Institute of Pharmacology and Clinical Pharmacy, Goethe University, Frankfurt am Main, Germany
| | - Achim Schmidtko
- Institute of Pharmacology and Clinical Pharmacy, Goethe University, Frankfurt am Main, Germany
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Omarjee L, Le Pabic E, Custaud MA, Fontaine C, Locher C, Renault A, Jaquinandi V, Azzola V, Barbeau-Terrier C, Laporte I, Ripoche M, Onillon Y, Chretien JM, Daniel V, Chao de la Barca JM, Homedan C, Reynier P, Abraham P, Mahé G. Effects of sildenafil on maximum walking time in patients with arterial claudication: The ARTERIOFIL study. Vascul Pharmacol 2019; 118-119:106563. [DOI: 10.1016/j.vph.2019.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 05/07/2019] [Accepted: 05/26/2019] [Indexed: 01/18/2023]
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Zakaria ZA, Abdul Rahim MH, Mohd Sani MH, Omar MH, Ching SM, Abdul Kadir A, Ahmed QU. Antinociceptive activity of petroleum ether fraction obtained from methanolic extract of Clinacanthus nutans leaves involves the activation of opioid receptors and NO-mediated/cGMP-independent pathway. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2019; 19:79. [PMID: 30940120 PMCID: PMC6446312 DOI: 10.1186/s12906-019-2486-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 03/20/2019] [Indexed: 12/18/2022]
Abstract
BACKGROUND Methanol extract (MECN) of Clinacanthus nutans Lindau leaves (family Acanthaceae) demonstrated peripherally and centrally mediated antinociceptive activity via the modulation of opioid/NO-mediated, but cGMP-independent pathway. In the present study, MECN was sequentially partitioned to obtain petroleum ether extract of C. nutans (PECN), which was subjected to antinociceptive study with aims of establishing its antinociceptive potential and determining the role of opioid receptors and L-arginine/nitric oxide/cyclic-guanosine monophosphate (L-arg/NO/cGMP) pathway in the observed antinociceptive activity. METHODS The antinociceptive potential of orally administered PECN (100, 250, 500 mg/kg) was studied using the abdominal constriction-, hot plate- and formalin-induced paw licking-test in mice (n = 6). The effect of PECN on locomotor activity was also evaluated using the rota rod assay. The role of opioid receptors was determined by pre-challenging 500 mg/kg PECN (p.o.) with antagonist of opioid receptor subtypes, namely β-funaltrexamine (β-FNA; 10 mg/kg; a μ-opioid antagonist), naltrindole (NALT; 1 mg/kg; a δ-opioid antagonist) or nor-binaltorphimine (nor-BNI; 1 mg/kg; a κ-opioid antagonist) followed by subjection to the abdominal constriction test. In addition, the role of L-arg/NO/cGMP pathway was determined by prechallenging 500 mg/kg PECN (p.o.) with L-arg (20 mg/kg; a NO precursor), 1H-[1, 2, 4] oxadiazolo [4,3-a]quinoxalin-1-one (ODQ; 2 mg/kg; a specific soluble guanylyl cyclase inhibitor), or the combinations thereof (L-arg + ODQ) for 5 mins before subjection to the abdominal constriction test. PECN was also subjected to phytoconstituents analyses. RESULTS PECN significantly (p < 0.05) inhibited nociceptive effect in all models in a dose-dependent manner. The highest dose of PECN (500 mg/kg) also did not significantly (p > 0.05) affect the locomotor activity of treated mice. The antinociceptive activity of PECN was significantly (p < 0.05) inhibited by all antagonists of μ-, δ-, and κ-opioid receptors. In addition, the antinociceptive activity of PECN was significantly (p < 0.05) reversed by L-arg, but insignificantly (p > 0.05) affected by ODQ. HPLC analysis revealed the presence of at least cinnamic acid in PECN. CONCLUSION PECN exerted antinocicpetive activity at peripheral and central levels possibly via the activation of non-selective opioid receptors and modulation of the NO-mediated/cGMP-independent pathway partly via the synergistic action of phenolic compounds.
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Omarjee L, Fontaine C, Mahe G, Jaquinandi V. Improvement of peripheral artery disease with Sildenafil and Bosentan combined therapy in a patient with limited cutaneous systemic sclerosis: A case report. Medicine (Baltimore) 2017; 96:e6988. [PMID: 28640077 PMCID: PMC5484185 DOI: 10.1097/md.0000000000006988] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
RATIONALE Sildenafil, a phosphodiesterase-5-inhibitor and Bosentan, an endothelin-1-receptor antagonist combined therapy could have beneficial effect in systemic sclerosis (SSc) patients with peripheral artery disease. PATIENT CONCERNS We report a case of a 48-year-old Black woman, who developed severe left limb claudication and walking limitation following a left femoropopliteal bypass occlusion in 2014. She was a heavy smoker and had a history of right middle cerebral artery ischemic stroke and bilateral Raynaud phenomenon. DIAGNOSES According to the American College of Rheumatology/European League Against Rheumatism-2013 criteria, diagnosis of limited cutaneous SSc was retained with macrovascular lesions. She was referred for investigation of left limb claudication on treadmill using transcutaneous oxygen pressure measurement during exercise to argue for the vascular origin of the walking impairment. She had a severe left limb ischemia and the maximum walking distance (MWD) she reached was 118 m in March 2015 despite the medical optimal treatment and walking rehabilitation. INTERVENTIONS Sildenafil, 20 mg tid, was introduced due to active digital ulcers. In July 2015, the MWD increased to 288 m, then to 452 m in December 2015. Adding Bosentan to Sildenafil to prevent recurrent digital ulcers resulted in an MWD of 1576 m. OUTCOMES Recently, the patient is treated with the combined therapy. She has no more pain during walking and his quality of life has improved. LESSONS Sildenafil and Bosentan combined therapy was associated in our case with an improvement of MWD without adverse effect. Further clinical trials are necessary to confirm our original observation.
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Affiliation(s)
- Loukman Omarjee
- Unité de Médecine Vasculaire, INSERM CIC 1414, Pôle Imagerie Médicale et Explorations Fonctionnelles, CHU de Rennes, 35033 Rennes Cedex, France
- MitoVasc Institute, UMR CNRS 6015—INSERM U1083, Angers University Hospital, Angers Cedex
| | - Cedric Fontaine
- Unité de Médecine Vasculaire, Plateau des Consultations Médicales, Cholet Cedex France
| | - Guillaume Mahe
- Unité de Médecine Vasculaire, INSERM CIC 1414, Pôle Imagerie Médicale et Explorations Fonctionnelles, CHU de Rennes, 35033 Rennes Cedex, France
| | - Vincent Jaquinandi
- Unité de Médecine Vasculaire, INSERM CIC 1414, Pôle Imagerie Médicale et Explorations Fonctionnelles, CHU de Rennes, 35033 Rennes Cedex, France
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Omarjee L, Camarzana A, Henni S, Abraham P. Nonrevascularizable buttock claudication improved with Sildenafil: A case report. Medicine (Baltimore) 2017; 96:e6186. [PMID: 28225505 PMCID: PMC5569413 DOI: 10.1097/md.0000000000006186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
RATIONALE Sildenafil, a phosphodiesterase-5-inhibitor (PDE5i), could represent a new treatment in addition to the medical treatment and advice to walk in peripheral arterial disease (PAD). PATIENT CONCERNS AND DIAGNOSES We report a case of a 62-year-old heavy smoker man who developed a buttock claudication and a severe walking limitation following an aorto-bi-femoral bypass in 1992. Since 2003, each year, he has been referred for investigation of bilateral buttock claudication on treadmill using transcutaneous oxygen pressure (tcpO2) measurement during exercise to argue for the vascular origin of the walking impairment. He had a severe bilateral buttock ischemia and the maximum walking distance (MWD) he reached was 258 m in 2011 despite the medical optimal treatment and walking rehabilitation. Ethical approval is not necessary for this case report according to the French legislation and written consent to publication was obtained from the patient. INTERVENTIONS Sildenafil, 100 mg/d, was introduced in February 2015 and the MWD increased to 310 m only after 2 h after the first oral intake, then to 713 m after 3 weeks, and finally to 1313 m in January 2017. OUTCOMES Recently, the patient is treated with Sildenafil 100 mg/d. He has no more pain during walking and his quality of life has improved. MAIN LESSONS TO LEARN Sildenafil, a PDE5i, may represent a new therapeutic option in addition to the conventional optimal medical therapy in patients with arterial claudication. tcpO2 measurement during exercise is a promising technique for the diagnosis and monitoring of patients with PAD. A crossover, double-blind, prospective randomized monocenter study (ARTERIOFIL-NCT02832570) and a double-blind prospective randomized multicenter study (VALSTAR-NCT02930811) are ongoing to confirm our original observation.
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Affiliation(s)
- Loukman Omarjee
- Vascular Investigations and Physiology Department, Angers University Hospital
- MitoVasc Institute, UMR CNRS 6015, INSERM U1083, Angers University, Angers, France
| | - Audrey Camarzana
- Vascular Investigations and Physiology Department, Angers University Hospital
| | - Samir Henni
- Vascular Investigations and Physiology Department, Angers University Hospital
- MitoVasc Institute, UMR CNRS 6015, INSERM U1083, Angers University, Angers, France
| | - Pierre Abraham
- Vascular Investigations and Physiology Department, Angers University Hospital
- MitoVasc Institute, UMR CNRS 6015, INSERM U1083, Angers University, Angers, France
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Repeated Mu-Opioid Exposure Induces a Novel Form of the Hyperalgesic Priming Model for Transition to Chronic Pain. J Neurosci 2015; 35:12502-17. [PMID: 26354917 DOI: 10.1523/jneurosci.1673-15.2015] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The primary afferent nociceptor was used as a model system to study mechanisms of pain induced by chronic opioid administration. Repeated intradermal injection of the selective mu-opioid receptor (MOR) agonist DAMGO induced mechanical hyperalgesia and marked prolongation of prostaglandin E2 (PGE2) hyperalgesia, a key feature of hyperalgesic priming. However, in contrast to prior studies of priming induced by receptor-mediated (i.e., TNFα, NGF, or IL-6 receptor) or direct activation of protein kinase Cε (PKCε), the pronociceptive effects of PGE2 in DAMGO-treated rats demonstrated the following: (1) rapid induction (4 h compared with 3 d); (2) protein kinase A (PKA), rather than PKCε, dependence; (3) prolongation of hyperalgesia induced by an activator of PKA, 8-bromo cAMP; (4) failure to be reversed by a protein translation inhibitor; (5) priming in females as well as in males; and (6) lack of dependence on the isolectin B4-positive nociceptor. These studies demonstrate a novel form of hyperalgesic priming induced by repeated administration of an agonist at the Gi-protein-coupled MOR to the peripheral terminal of the nociceptor. Significance statement: The current study demonstrates the molecular mechanisms involved in the sensitization of nociceptors produced by repeated activation of mu-opioid receptors and contributes to our understanding of the painful condition observed in patients submitted to chronic use of opioids.
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Li H, Shang XJ, Dong QR. Effects of Transcutaneous Electrical Nerve Stimulation on Rats with the Third Lumbar Vertebrae Transverse Process Syndrome. Acupunct Med 2015; 33:400-5. [PMID: 26104377 DOI: 10.1136/acupmed-2014-010752] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2015] [Indexed: 11/03/2022]
Abstract
Objective To investigate the analgesic and anti-inflammatory effects of transcutaneous electrical nerve stimulation (TENS) at local or distant acupuncture points in a rat model of the third lumbar vertebrae transverse process syndrome. Methods Forty Sprague–Dawley rats were randomly divided into control, model, model plus local acupuncture point stimulation at BL23 (model+LAS) and model plus distant acupuncture point stimulation at ST36 (model+DAS) groups. All rats except controls underwent surgical third lumbar vertebrae transverse process syndrome modelling on day 2. Thereafter, rats in the model+LAS and model+DAS groups were treated daily with TENS for a total of six treatments (2/100 Hz, 30 min/day) from day 16 to day 29. Thermal pain thresholds were measured once a week during treatment and were continued until day 57, when local muscle tissue was sampled for RT-PCR and histopathological examination after haematoxylin and eosin staining. mRNA expression of interleukin-1 β (IL-1β), tumour necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) was determined. Results Thermal pain thresholds of all model rats decreased relative to the control group. Both LAS and DAS significantly increased the thermal pain threshold at all but one point during the treatment period. Histopathological assessment revealed that the local muscle tissues around the third lumbar vertebrae transverse process recovered to some degree in both the model+LAS and model+DAS groups; however, LAS appeared to have a greater effect. mRNA expression of IL-1β, TNF-α and iNOS in the local muscle tissues was increased after modelling and attenuated in both model+LAS and model+DAS groups. The beneficial effect was greater after LAS than after DAS. Conclusions TENS at both local (BL23) and distant (ST36) acupuncture points had a pain-relieving effect in rats with the third lumbar vertebrae transverse process syndrome, and LAS appeared to have greater anti-inflammatory and analgesic effects than DAS. Trial Registration Number 09073.
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Affiliation(s)
- Huan Li
- Department of Orthopaedics, The Second Affiliated Hospital of Suzhou University, Suzhou, China
- Department of Orthopaedics, The First People's Hospital of Changzhou and the Third Affiliated Hospital of Suzhou University, Changzhou, China
| | - Xiao-Jun Shang
- Department of Orthopaedics, The First People's Hospital of Changzhou and the Third Affiliated Hospital of Suzhou University, Changzhou, China
| | - Qi-Rong Dong
- Department of Orthopaedics, The Second Affiliated Hospital of Suzhou University, Suzhou, China
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Freitas CS, Roveda AC, Truzzi DR, Garcia AC, Cunha TM, Cunha FQ, Franco DW. Anti-inflammatory and Anti-nociceptive Activity of Ruthenium Complexes with Isonicotinic and Nicotinic Acids (Niacin) as Ligands. J Med Chem 2015; 58:4439-48. [DOI: 10.1021/acs.jmedchem.5b00133] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Cristina S. Freitas
- Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, CEP 14049-900, Ribeirão Preto, SP, Brazil
| | - Antonio C. Roveda
- Instituto de Química de São Carlos, Universidade de São Paulo−USP, P.O. Box 780, CEP 13566-590, São Carlos, SP, Brazil
| | - Daniela R. Truzzi
- Instituto de Química de São Carlos, Universidade de São Paulo−USP, P.O. Box 780, CEP 13566-590, São Carlos, SP, Brazil
| | - André C. Garcia
- Instituto de Química de São Carlos, Universidade de São Paulo−USP, P.O. Box 780, CEP 13566-590, São Carlos, SP, Brazil
| | - Thiago M. Cunha
- Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, CEP 14049-900, Ribeirão Preto, SP, Brazil
| | - Fernando Q. Cunha
- Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, CEP 14049-900, Ribeirão Preto, SP, Brazil
| | - Douglas W. Franco
- Instituto de Química de São Carlos, Universidade de São Paulo−USP, P.O. Box 780, CEP 13566-590, São Carlos, SP, Brazil
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Li J, Xue B, Han T, Huang K, Gong L, Ma X, Liu K, Cui S, Zhang M, Kunze W, Liu C. Oxytocin down-regulates mesenteric afferent sensitivity via the enteric OTR/nNOS/NO/KATP pathway in rat. Neurogastroenterol Motil 2015; 27:51-62. [PMID: 25346204 DOI: 10.1111/nmo.12469] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 10/08/2014] [Indexed: 12/21/2022]
Abstract
BACKGROUND Oxytocin plays an analgesic role in modulation of nociception and pain. Most work to date has focused on the central mechanisms of oxytocin analgesia, but little is known about whether peripheral mechanisms are also involved. METHODS The mesenteric afferent discharge was recorded in vitro. The expressions of oxytocin receptor (OTR) and neuronal nitric oxide synthase (nNOS) in longitudinal muscle myenteric plexus (LMMP) was identified by immunofluorescence. KEY RESULTS Oxytocin per se had no effect on the jejunal mesenteric afferent discharge, however, it markedly attenuated the bradykinin- or distention-evoked increase of mesenteric afferent discharge, which was mimiced by the nitric oxide (NO) donor sodium nitroprusside (SNP). Pretreatment of either NOS inhibitor L-NAME or NPLA largely reduced the inhibitory effect of oxytocin on bradykinin-evoked mesenteric afferent discharge. Such effect, to a large extent, was also alleviated by N-and P-type voltage-dependent calcium channel antagonists or KATP blocker glibenclamide. In addition, immunofluorescence studies show strong colocalization of OTR with nNOS in LMMP of the rat jejunum. CONCLUSIONS & INFERENCES Oxytocin down-regulates the mesenteric afferent sensitivity through nNOS-NO-KATP pathway. Our findings may reveal a new peripheral mechanism for oxytocin analgesia.
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Affiliation(s)
- J Li
- Department of Physiology, Shandong Provincial Key Laboratory of Mental Disorders, Shandong University School of Medicine, Jinan, China
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Guo C, Liu N, Li X, Sun H, Hu B, Lu J, Guo Y, Liang C, Xu H, Wu H. Effect of acupotomy on nitric oxide synthase and beta-endorphin in third lumbar vertebrae transverse process syndrome model rats. J TRADIT CHIN MED 2014; 34:194-8. [DOI: 10.1016/s0254-6272(14)60078-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Castro J, Harrington AM, Hughes PA, Martin CM, Ge P, Shea CM, Jin H, Jacobson S, Hannig G, Mann E, Cohen MB, MacDougall JE, Lavins BJ, Kurtz CB, Silos-Santiago I, Johnston JM, Currie MG, Blackshaw LA, Brierley SM. Linaclotide inhibits colonic nociceptors and relieves abdominal pain via guanylate cyclase-C and extracellular cyclic guanosine 3',5'-monophosphate. Gastroenterology 2013; 145:1334-46.e1-11. [PMID: 23958540 DOI: 10.1053/j.gastro.2013.08.017] [Citation(s) in RCA: 190] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 08/02/2013] [Accepted: 08/13/2013] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Linaclotide is a minimally absorbed agonist of guanylate cyclase-C (GUCY2C or GC-C) that reduces symptoms associated with irritable bowel syndrome with constipation (IBS-C). Little is known about the mechanism by which linaclotide reduces abdominal pain in patients with IBS-C. METHODS We determined the effects of linaclotide on colonic sensory afferents in healthy mice and those with chronic visceral hypersensitivity. We assessed pain transmission by measuring activation of dorsal horn neurons in the spinal cord in response to noxious colorectal distention. Levels of Gucy2c messenger RNA were measured in tissues from mice using quantitative reverse transcription polymerase chain reaction and in situ hybridization. We used human intestinal cell lines to measure release of cyclic guanosine-3',5'-monophosphate (cGMP) by linaclotide. We performed a post-hoc analysis of data from a phase III, double-blind, parallel-group study in which 805 patients with IBS-C were randomly assigned to groups given an oral placebo or 290 μg linaclotide once daily for 26 weeks. We quantified changes in IBS-C symptoms, including abdominal pain. RESULTS In mice, linaclotide inhibited colonic nociceptors with greater efficacy during chronic visceral hypersensitivity. Intra-colonic administration of linaclotide reduced signaling of noxious colorectal distention to the spinal cord. The colonic mucosa, but not neurons, was found to express linaclotide's target, GC-C. The downstream effector of GC-C, cGMP, was released after administration of linaclotide and also inhibited nociceptors. The effects of linaclotide were lost in Gucy2c(-/-) mice and prevented by inhibiting cGMP transporters or removing the mucosa. During 26 weeks of linaclotide administration, a significantly greater percentage of patients (70%) had at least a 30% reduction in abdominal pain compared with patients given placebo (50%). CONCLUSIONS We have identified an analgesic mechanism of linaclotide: it activates GC-C expressed on mucosal epithelial cells, resulting in the production and release of cGMP. This extracellular cGMP acts on and inhibits nociceptors, thereby reducing nociception. We also found that linaclotide reduces chronic abdominal pain in patients with IBS-C.
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Affiliation(s)
- Joel Castro
- Nerve-Gut Research Laboratory, Discipline of Medicine, Faculty of Health Sciences, The University of Adelaide, Adelaide, South Australia, Australia; Department of Gastroenterology and Hepatology, Hanson Institute, Royal Adelaide Hospital, Adelaide, South Australia, Australia
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