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Vidal-Torres A, Fernández-Pastor B, García M, Ayet E, Cabot A, Burgueño J, Monroy X, Aubel B, Codony X, Romero L, Pascual R, Serafini MT, Encina G, Almansa C, Zamanillo D, Merlos M, Vela JM. Bispecific sigma-1 receptor antagonism and mu-opioid receptor partial agonism: WLB-73502, an analgesic with improved efficacy and safety profile compared to strong opioids. Acta Pharm Sin B 2023; 13:82-99. [PMID: 36815042 PMCID: PMC9939367 DOI: 10.1016/j.apsb.2022.09.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 06/17/2022] [Accepted: 07/18/2022] [Indexed: 11/01/2022] Open
Abstract
Opioids are the most effective painkillers, but their benefit-risk balance often hinder their therapeutic use. WLB-73502 is a dual, bispecific compound that binds sigma-1 (S1R) and mu-opioid (MOR) receptors. WLB-73502 is an antagonist at the S1R. It behaved as a partial MOR agonist at the G-protein pathway and produced no/unsignificant β-arrestin-2 recruitment, thus demonstrating low intrinsic efficacy on MOR at both signalling pathways. Despite its partial MOR agonism, WLB-73502 exerted full antinociceptive efficacy, with potency superior to morphine and similar to oxycodone against nociceptive, inflammatory and osteoarthritis pain, and superior to both morphine and oxycodone against neuropathic pain. WLB-73502 crosses the blood-brain barrier and binds brain S1R and MOR to an extent consistent with its antinociceptive effect. Contrary to morphine and oxycodone, tolerance to its antinociceptive effect did not develop after repeated 4-week administration. Also, contrary to opioid comparators, WLB-73502 did not inhibit gastrointestinal transit or respiratory function in rats at doses inducing full efficacy, and it was devoid of proemetic effect (retching and vomiting) in ferrets at potentially effective doses. WLB-73502 benefits from its bivalent S1R antagonist and partial MOR agonist nature to provide an improved antinociceptive and safety profile respect to strong opioid therapy.
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Carcolé M, Zamanillo D, Merlos M, Fernández-Pastor B, Cabañero D, Maldonado R. Blockade of the Sigma-1 Receptor Relieves Cognitive and Emotional Impairments Associated to Chronic Osteoarthritis Pain. Front Pharmacol 2019; 10:468. [PMID: 31130863 PMCID: PMC6510262 DOI: 10.3389/fphar.2019.00468] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/12/2019] [Indexed: 12/30/2022] Open
Abstract
Osteoarthritis is the most common musculoskeletal disease worldwide, often characterized by degradation of the articular cartilage, chronic joint pain and disability. Cognitive dysfunction, anxiety and depression are common comorbidities that impact the quality of life of these patients. In this study, we evaluated the involvement of sigma-1 receptor (σ1R) on the nociceptive, cognitive and emotional alterations associated with chronic osteoarthritis pain. Monosodium iodoacetate (MIA) was injected into the knee of Swiss-albino CD1 mice to induce osteoarthritis pain, which then received a repeated treatment with the σ1R antagonist E-52862 or its vehicle. Nociceptive responses and motor performance were assessed with the von Frey and the Catwalk gait tests. Cognitive alterations were evaluated using the novel object recognition task, anxiety-like behavior with the elevated plus maze and the zero-maze tests, whereas depressive-like responses were determined using the forced swimming test. We also studied the local effect of the σ1R antagonist on cartilage degradation, and its central effects on microglial reactivity in the medial prefrontal cortex. MIA induced mechanical allodynia and gait abnormalities that were prevented by the chronic treatment with the σ1R antagonist. E-52862 also reduced the memory impairment and the depressive-like behavior associated to osteoarthritis pain. Interestingly, the effect of E-52862 on depressive-like behavior was not accompanied by a modification of anxiety-like behavior. The pain-relieving effects of the σ1R antagonist were not due to a local effect on the articular cartilage, since E-52862 treatment did not modify the histological alterations of the knee joints. However, E-52862 induced central effects revealed by a reduction of the cortical microgliosis observed in mice with osteoarthritis pain. These findings show that σ1R antagonism inhibits mechanical hypersensitivity, cognitive deficits and depressive-like states associated with osteoarthritis pain in mice. These effects are associated with central modulation of glial activity but are unrelated to changes in cartilage degradation. Therefore, targeting the σ1R with E-52862 represents a promising pharmacological approach with effects on multiple aspects of chronic osteoarthritis pain that may go beyond the strict inhibition of nociception.
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Affiliation(s)
- Mireia Carcolé
- Neuropharmacology Laboratory, Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | - Daniel Zamanillo
- Drug Discovery and Preclinical Development, Laboratories Esteve, Barcelona Science Park, Barcelona, Spain
| | - Manuel Merlos
- Drug Discovery and Preclinical Development, Laboratories Esteve, Barcelona Science Park, Barcelona, Spain
| | - Begoña Fernández-Pastor
- Drug Discovery and Preclinical Development, Laboratories Esteve, Barcelona Science Park, Barcelona, Spain
| | - David Cabañero
- Neuropharmacology Laboratory, Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
| | - Rafael Maldonado
- Neuropharmacology Laboratory, Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
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Vidal-Torres A, Fernández-Pastor B, Carceller A, Vela JM, Merlos M, Zamanillo D. Supraspinal and Peripheral, but Not Intrathecal, σ 1R Blockade by S1RA Enhances Morphine Antinociception. Front Pharmacol 2019; 10:422. [PMID: 31068818 PMCID: PMC6491787 DOI: 10.3389/fphar.2019.00422] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 04/03/2019] [Indexed: 12/26/2022] Open
Abstract
Sigma-1 receptor (σ1R) antagonism increases the effects of morphine on acute nociceptive pain. S1RA (E-52862) is a selective σ1R antagonist widely used to study the role of σ1Rs. S1RA alone exerted antinociceptive effect in the formalin test in rats and increased noradrenaline levels in the spinal cord, thus accounting for its antinociceptive effect. Conversely, while systemic S1RA failed to elicit antinociceptive effect by itself in the tail-flick test in mice, it did potentiate the antinociceptive effect of opioids in this acute pain model. The present study aimed to investigate the site of action and the involvement of spinal noradrenaline on the potentiation of opioid antinociception by S1RA on acute thermal nociception using the tail-flick test in rats. Local administration was performed after intrathecal catheterization or intracerebroventricular and rostroventral medullar (RVM) cannulae implantation. Noradrenaline levels in the spinal cord were evaluated using the concentric microdialysis technique in awake, freely-moving rats. Systemic or supraspinal administration of S1RA alone, while having no effect on antinociception, enhanced the effect of morphine in rats. However, spinal S1RA administration did not potentiate the antinociceptive effect of morphine. Additionally, the peripherally restricted opioid agonist loperamide was devoid of antinociceptive effect but produced antinociception when combined with S1RA. Neurochemical studies revealed that noradrenaline levels in the dorsal horn of the spinal cord were not increased at doses exerting potentiation of the antinociceptive effect of the opioid. In conclusion, the site of action of σ1R for opioid modulation on acute thermal nociception is located at the peripheral and supraspinal levels, and the opioid-potentiating effect is independent of the spinal noradrenaline increase produced by S1RA.
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Affiliation(s)
- Alba Vidal-Torres
- Drug Discovery and Preclinical Development, Esteve Pharmaceuticals, Parc Científic Barcelona, Barcelona, Spain
| | - Begoña Fernández-Pastor
- Drug Discovery and Preclinical Development, Esteve Pharmaceuticals, Parc Científic Barcelona, Barcelona, Spain
| | - Alicia Carceller
- Drug Discovery and Preclinical Development, Esteve Pharmaceuticals, Parc Científic Barcelona, Barcelona, Spain
| | - José Miguel Vela
- Drug Discovery and Preclinical Development, Esteve Pharmaceuticals, Parc Científic Barcelona, Barcelona, Spain
| | - Manuel Merlos
- Drug Discovery and Preclinical Development, Esteve Pharmaceuticals, Parc Científic Barcelona, Barcelona, Spain
| | - Daniel Zamanillo
- Drug Discovery and Preclinical Development, Esteve Pharmaceuticals, Parc Científic Barcelona, Barcelona, Spain
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Fernández-Pastor B, Ortega JE, Grandoso L, Castro E, Ugedo L, Pazos Á, Meana JJ. Chronic citalopram administration desensitizes prefrontal cortex but not somatodendritic α 2-adrenoceptors in rat brain. Neuropharmacology 2016; 114:114-122. [PMID: 27908769 DOI: 10.1016/j.neuropharm.2016.11.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/18/2016] [Accepted: 11/26/2016] [Indexed: 12/27/2022]
Abstract
Selective serotonin reuptake inhibitors (SSRIs) regulate brain noradrenergic neurotransmission both at somatodendritic and nerve terminal areas. Previous studies have demonstrated that noradrenaline (NA) reuptake inhibitors are able to desensitize α2-adrenoceptor-mediated responses. The present study was undertaken to elucidate the effects of repeated treatment with the SSRI citalopram on the α2-adrenoceptor sensitivity in locus coeruleus (LC) and prefrontal cortex (PFC), by using in vivo microdialysis and electrophysiological techniques, and in vitro stimulation of [35S]GTPγS binding autoradiography. Repeated, but not acute, treatment with citalopram (5 mg/kg, i.p., 14 days) increased extracellular NA concentration selectively in PFC. The α2-adrenoceptor agonist clonidine (0.3 mg/kg, i.p.), administered to saline-treated animals (1 ml/kg i.p., 14 days) induced NA decrease in LC (Emax = -44 ± 4%; p < 0.001) and in PFC (Emax = -61 ± 5%, p < 0.001). In citalopram chronically-treated rats, clonidine administration exerted a lower decrease of NA (Emax = -25 ± 7%; p < 0.001) in PFC whereas the effect in LC was not different to controls (Emax = -36 ± 4%). Clonidine administration (0.625-20 μg/kg, i.v.) evoked a dose-dependent decrease of the firing activity of LC noradrenergic neurons in both citalopram- (ED50 = 3.2 ± 0.4 μg/kg) and saline-treated groups (ED50 = 2.6 ± 0.5 μg/kg). No significant differences between groups were found in ED50 values. The α2-adrenoceptor agonist UK14304 stimulated specific [35S]GTPγS binding in brain sections containing LC (144 ± 14%) and PFC (194 ± 32%) of saline-treated animals. In citalopram-treated animals, this increase did not differ from controls in LC (146 ± 22%) but was lower in PFC (141 ± 8%; p < 0.05). Taken together, long-term citalopram treatment induces a desensitization of α2-adrenoceptors acting as axon terminal autoreceptors in PFC without changes in somatodendritic α2-adrenoceptor sensitivity.
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Affiliation(s)
| | - Jorge E Ortega
- Department of Pharmacology, University of the Basque Country UPV/EHU, Leioa, Bizkaia, Spain; Centro de Investigación Biomédica en Red de Salud Mental CIBERSAM, Spain; BioCruces Health Research Institute, Bizkaia, Spain.
| | - Laura Grandoso
- Department of Pharmacology, University of the Basque Country UPV/EHU, Leioa, Bizkaia, Spain
| | - Elena Castro
- Centro de Investigación Biomédica en Red de Salud Mental CIBERSAM, Spain; Department of Physiology and Pharmacology, Institute of Biomedicine & Biotechnology of Cantabria (IBBTEC), University of Cantabria-CSIC-IDICAN, Santander, Cantabria, Spain
| | - Luisa Ugedo
- Department of Pharmacology, University of the Basque Country UPV/EHU, Leioa, Bizkaia, Spain
| | - Ángel Pazos
- Centro de Investigación Biomédica en Red de Salud Mental CIBERSAM, Spain; Department of Physiology and Pharmacology, Institute of Biomedicine & Biotechnology of Cantabria (IBBTEC), University of Cantabria-CSIC-IDICAN, Santander, Cantabria, Spain
| | - J Javier Meana
- Department of Pharmacology, University of the Basque Country UPV/EHU, Leioa, Bizkaia, Spain; Centro de Investigación Biomédica en Red de Salud Mental CIBERSAM, Spain; BioCruces Health Research Institute, Bizkaia, Spain
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Vidal-Torres A, Fernández-Pastor B, Carceller A, Vela JM, Merlos M, Zamanillo D. Effects of the selective sigma-1 receptor antagonist S1RA on formalin-induced pain behavior and neurotransmitter release in the spinal cord in rats. J Neurochem 2014; 129:484-94. [PMID: 24384038 DOI: 10.1111/jnc.12648] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 12/03/2013] [Accepted: 12/30/2013] [Indexed: 12/21/2022]
Abstract
We have previously shown that the selective sigma-1 receptor (σ1 R) antagonist S1RA (E-52862) inhibits neuropathic pain and activity-induced spinal sensitization in various pre-clinical pain models. In this study we characterized both the behavioral and the spinal neurochemical effects of S1RA in the rat formalin test. Systemic administration of S1RA produced a dose-related attenuation of flinching and lifting/licking behaviors in the formalin test. Neurochemical studies using concentric microdialysis in the ipsilateral dorsal horn of awake, freely moving rats revealed that the systemic S1RA-induced antinociceptive effect occurs concomitantly with an enhancement of noradrenaline levels and an attenuation of formalin-evoked glutamate release in the spinal dorsal horn. Intrathecal pre-treatment with idazoxan prevented the systemic S1RA antinociceptive effect, suggesting that the S1RA antinociception depends on the activation of spinal α2 -adrenoceptors which, in turn, could induce an inhibition of formalin-evoked glutamate release. When administered locally, intrathecal S1RA inhibited only the flinching behavior, whereas intracerebroventricularly or intraplantarly injected also attenuated the lifting/licking behavior. These results suggest that S1RA supraspinally activates the descending noradrenergic pain inhibitory system, which may explain part of its antinociceptive properties in the formalin test; however, effects at other central and peripheral sites also account for the overall effect. Formalin-induced nociceptive effect occurs concomitantly with an enhancement of glutamate (Glu) level in the dorsal horn spinal cord. The selective σ1 receptor antagonist S1RA results in inhibition of formalin-evoked Glu release, no modification of GABA levels, and enhancement of noradrenaline (NA) levels. This increased spinal NA activates spinal α2-adrenoceptors producing the attenuation of the formalin-induced pain behaviour.
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Affiliation(s)
- Alba Vidal-Torres
- Drug Discovery and Preclinical Development, Laboratorios Esteve. Parc Científic Barcelona, Barcelona, Spain
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Sánchez-Fernández C, Montilla-García Á, González-Cano R, Nieto FR, Romero L, Artacho-Cordón A, Montes R, Fernández-Pastor B, Merlos M, Baeyens JM, Entrena JM, Cobos EJ. Modulation of peripheral μ-opioid analgesia by σ1 receptors. J Pharmacol Exp Ther 2014; 348:32-45. [PMID: 24155346 DOI: 10.1124/jpet.113.208272] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We evaluated the effects of σ1-receptor inhibition on μ-opioid-induced mechanical antinociception and constipation. σ1-Knockout mice exhibited marked mechanical antinociception in response to several μ-opioid analgesics (fentanyl, oxycodone, morphine, buprenorphine, and tramadol) at systemic (subcutaneous) doses that were inactive in wild-type mice and even unmasked the antinociceptive effects of the peripheral μ-opioid agonist loperamide. Likewise, systemic (subcutaneous) or local (intraplantar) treatment of wild-type mice with the selective σ1 antagonists BD-1063 [1-[2-(3,4-dichlorophenyl)ethyl]-4-methylpiperazine dihydrochloride] or S1RA [4-[2-[[5-methyl-1-(2-naphthalenyl)1H-pyrazol-3-yl]oxy]ethyl] morpholine hydrochloride] potentiated μ-opioid antinociception; these effects were fully reversed by the σ1 agonist PRE-084 [2-(4-morpholinethyl)1-phenylcyclohexanecarboxylate) hydrochloride], showing the selectivity of the pharmacological approach. The μ-opioid antinociception potentiated by σ1 inhibition (by σ1-receptor knockout or σ1-pharmacological antagonism) was more sensitive to the peripherally restricted opioid antagonist naloxone methiodide than opioid antinociception under normal conditions, indicating a key role for peripheral opioid receptors in the enhanced antinociception. Direct interaction between the opioid drugs and σ1 receptor cannot account for our results, since the former lacked affinity for σ1 receptors (labeled with [(3)H](+)-pentazocine). A peripheral role for σ1 receptors was also supported by their higher density (Western blot results) in peripheral nervous tissue (dorsal root ganglia) than in several central areas involved in opioid antinociception (dorsal spinal cord, basolateral amygdala, periaqueductal gray, and rostroventral medulla). In contrast to its effects on nociception, σ1-receptor inhibition did not alter fentanyl- or loperamide-induced constipation, a peripherally mediated nonanalgesic opioid effect. Therefore, σ1-receptor inhibition may be used as a systemic or local adjuvant to enhance peripheral μ-opioid analgesia without affecting opioid-induced constipation.
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MESH Headings
- Analgesics, Opioid/antagonists & inhibitors
- Analgesics, Opioid/pharmacology
- Animals
- Constipation/chemically induced
- Constipation/genetics
- Constipation/metabolism
- Female
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/physiology
- Mice
- Mice, Knockout
- Pain Measurement/methods
- Receptors, Opioid, mu/metabolism
- Receptors, Opioid, mu/physiology
- Receptors, sigma/deficiency
- Receptors, sigma/genetics
- Receptors, sigma/physiology
- Sigma-1 Receptor
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Affiliation(s)
- Cristina Sánchez-Fernández
- Departments of Pharmacology (C.S.-F., A.M.-G., R.G.-C., F.R.N., L.R., A.A.-C., J.M.B., E.J.C.) and Physiology (R.M.), School of Medicine, University of Granada, Granada, Spain; Institute of Neuroscience, Biomedical Research Center, University of Granada, Granada, Spain (C.S.-F., R.G.-C., F.R.N., R.M., J.M.B., J.M.E., E.J.C.); Animal Behavior Research Unit, Scientific Instrumentation Center, University of Granada, Granada, Spain (J.M.E.); and Drug Discovery and Preclinical Development, Barcelona, Spain (B.F.-P., M.M.)
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Vidal-Torres A, de la Puente B, Rocasalbas M, Touriño C, Bura SA, Fernández-Pastor B, Romero L, Codony X, Zamanillo D, Buschmann H, Merlos M, Baeyens JM, Maldonado R, Vela JM. Sigma-1 receptor antagonism as opioid adjuvant strategy: enhancement of opioid antinociception without increasing adverse effects. Eur J Pharmacol 2013; 711:63-72. [PMID: 23632394 DOI: 10.1016/j.ejphar.2013.04.018] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 04/02/2013] [Accepted: 04/04/2013] [Indexed: 10/26/2022]
Abstract
While opioids are potent analgesics widely used in the management of pain, a number of well-known adverse effects limit their use. The sigma-1 receptor is a ligand-regulated molecular chaperone involved in pain processing, including modulation of opioid antinociception. However, data supporting the potential use of sigma-1 receptor ligands as suitable opioid adjuvants are based on studies that use non selective ligands. Also, safety issues derived from combination therapy are poorly addressed. In this study we used the new selective sigma-1 receptor antagonist S1RA (E-52862) to characterize the effect of selective sigma-1 receptor blockade on opioid-induced efficacy- and safety-related outcomes in mice. S1RA (40 mg/kg) had no effect in the tail-flick test but did enhance the antinociceptive potency of several opioids by a factor between 2 and 3.3. The potentiating effect of S1RA on morphine antinociception did not occur in sigma-1 receptor knockout mice, which supports the selective involvement of the sigma-1 receptor. Interestingly, S1RA co-administration restored morphine antinociception in tolerant mice and reverted the reward effects of morphine in the conditioned place preference paradigm. In addition, enhancement of antinociception was not accompanied by potentiation of other opioid-induced effects, such as the development of morphine analgesic tolerance, physical dependence, inhibition of gastrointestinal transit, or mydriasis. The use of sigma-1 receptor antagonists as opioid adjuvants could represent a promising pharmacological strategy to enhance opioid potency and, most importantly, to increase the safety margin of opioids. S1RA is currently in phase II clinical trials for the treatment of several pain conditions.
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Affiliation(s)
- Alba Vidal-Torres
- Esteve, Drug Discovery and Preclinical Development. Parc Científic de Barcelona. Carrer Baldiri Reixac, 4-8. 08028 Barcelona, Spain
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Vidal-Torres A, Carceller A, Zamanillo D, Merlos M, Vela JM, Fernández-Pastor B. Evaluation of formalin-induced pain behavior and glutamate release in the spinal dorsal horn using in vivo microdialysis in conscious rats. J Pharmacol Sci 2012; 120:129-32. [PMID: 22986364 DOI: 10.1254/jphs.12105sc] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Measurement of neurotransmitters in the spinal dorsal horn in conscious animals remains a technical challenge. Here we applied concentric microdialysis to measure formalin-induced glutamate (Glu) release in the ipsilateral dorsal horn in conscious, freely-moving rats. Hind paw formalin injection induced flinching nociceptive behaviors accompanied by increased Glu in the dorsal horn (maximum = 294%). Both flinching and Glu increase were prevented by morphine (3 mg/kg, s.c.). Accordingly, concentric microdialysis is a sensitive technique for studying neurochemical modulation induced by pain and analgesics in the spinal dorsal horn of awake rats. Measurement of Glu provides information on modulation of excitatory signals.
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Affiliation(s)
- Alba Vidal-Torres
- Department of Pharmacology, Drug Discovery and Preclinical Development, ESTEVE, Barcelona, Spain
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Fernández-Pastor B, Mateo Y, Gómez-Urquijo S, Javier Meana J. Characterization of noradrenaline release in the locus coeruleus of freely moving awake rats by in vivo microdialysis. Psychopharmacology (Berl) 2005; 180:570-9. [PMID: 15717207 DOI: 10.1007/s00213-005-2181-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2004] [Accepted: 01/10/2005] [Indexed: 11/26/2022]
Abstract
RATIONALE The origin and regulation of noradrenaline (NA) in the locus coeruleus (LC) is unknown. OBJECTIVES The neurochemical features of NA overflow (nerve impulse dependence, neurotransmitter synthesis, vesicle storage, reuptake, alpha2-adrenoceptor-mediated regulation) were characterized in the LC. METHODS Brain microdialysis was performed in awake rats. Dialysates were analyzed for NA. RESULTS NA in the LC decreased via local infusion of Ca2+-free medium (-42+/-5%) or the sodium channel blocker tetrodotoxine (TTX) (-47+/-8%) but increased (333+/-40%) via KCl-induced depolarization. The tyrosine hydroxylase (TH) inhibitor alpha-methyl-p-tyrosine (250 mg kg(-1), i.p.) and the vesicle depletory drug reserpine (5 mg kg(-1), i.p.) decreased NA. Therefore, extracellular NA in the LC satisfies the criteria for an impulse flow-dependent vesicular exocytosis of neuronal origin. Local perfusion of the alpha2-adrenoceptor agonist clonidine (0.1-100 microM) decreased NA (E(max)=-79+/-5%) in the LC, whereas the opposite effect (E(max)=268+/-53%) was observed with the alpha2A-adrenoceptor antagonist BRL44408 (0.1-100 microM). This suggests a tonic modulation of NA release through local alpha2A-adrenoceptors. The selective NA reuptake inhibitor desipramine (DMI) (0.1-100 microM) administered into the LC increased NA in the LC (E(max)=223+/-40%) and simultaneously decreased NA in the cingulate cortex, confirming the modulation exerted by NA in the LC on firing activity of noradrenergic cells and on the subsequent NA release in noradrenergic terminals. CONCLUSION Synaptic processes underlying NA release in the LC are similar to those in noradrenergic terminal areas. NA in the LC could represent local somatodendritic release, but also the presence of neurotransmitter release from collateral axon terminals.
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Fernández-Pastor B, Meana JJ. In vivo tonic modulation of the noradrenaline release in the rat cortex by locus coeruleus somatodendritic alpha(2)-adrenoceptors. Eur J Pharmacol 2002; 442:225-9. [PMID: 12065075 DOI: 10.1016/s0014-2999(02)01543-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The regulation of noradrenaline release in the rat cingulate cortex by somatodendritic alpha(2)-adrenoceptors placed in the locus coeruleus was evaluated by dual-probe microdialysis. The alpha(2)-adrenoceptor antagonists BRL44408 (2-[2H-(1-methyl-1,3-dihydroisoindole)methyl]-4,5-dihydroimidazole), RS79948 ((8,12,13)-decahydro-3methoxy-12-(ethylsulphonyl)-6H-isoquino[2,1-g][1,6]-naphthyridine) and RX821002 (2-methoxyidazoxan) administered by reverse dialysis into the locus coeruleus increased concentration-dependently (0.01-100 microM) noradrenaline release in the cortex (maximal effects 170+/-30%, 543+/-17%, 195+/-26%, respectively). Administration of the alpha(2)-adrenoceptor antagonist idazoxan increased at lower (0.1-10 microM) but decreased at the highest dose (100 microM) noradrenaline in the cortex. These data demonstrate that somatodendritic alpha(2)-adrenoceptors in the locus coeruleus exert an inhibitory tonic modulation on noradrenaline release in noradrenergic terminal areas.
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Affiliation(s)
- Begoña Fernández-Pastor
- Department of Pharmacology, University of the Basque Country, E-48940, Leioa, Bizkaia, Spain
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Mateo Y, Fernández-Pastor B, Meana JJ. Acute and chronic effects of desipramine and clorgyline on alpha(2)-adrenoceptors regulating noradrenergic transmission in the rat brain: a dual-probe microdialysis study. Br J Pharmacol 2001; 133:1362-70. [PMID: 11498523 PMCID: PMC1621148 DOI: 10.1038/sj.bjp.0704196] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The effects of desipramine (3 mg kg(-1) i.p.) and clorgyline (1 mg kg(-1) i.p.) on extracellular noradrenaline (NA) in the locus coeruleus (LC) and cingulate cortex were assessed in freely-moving rats by dual-probe microdialysis. Functional activities of alpha(2)-adrenoceptors regulating NA release in the LC and cingulate cortex were determined by systemic (0.3 mg kg(-1) i.p.) or local (0.1 - 100 microM) clonidine administration. 2. Extracellular NA was increased in the LC and cingulate cortex following acute desipramine but not clorgyline treatment. Systemic clonidine decreased NA similarly in desipramine-, clorgyline-, and saline-treated animals, in both brain areas. 3. Long-term (twice daily, 14 days) but not short-term (twice daily, 7 days) desipramine, and long-term clorgyline (once daily, 21 days) treatments increased NA (3 fold) in cingulate cortex but not in the LC. Following long-term treatments, responses of NA to systemic clonidine were attenuated in the LC and cingulate cortex. 4. Clonidine perfusion by reverse dialysis into the cingulate cortex decreased local NA (-55 +/- 9%). The effect was attenuated by long-term desipramine (-31 +/- 9%) and clorgyline (-10 +/- 2%) treatments. 5. Clonidine perfusion by reverse dialysis into the LC decreased NA in the LC (-89 +/- 2%) and in cingulate cortex (-52 +/- 12%). This effect was attenuated in the LC following long-term desipramine (-72 +/- 4%) and clorgyline (-62 +/- 12%) treatments but it was not modified in the cingulate cortex (-57 +/- 10% and -68 +/- 6%, respectively). 6. These findings demonstrate that chronic desipramine or clorgyline treatments increase NA in noradrenergic terminal areas and desensitize alpha(2)-adrenoceptors modulating local NA release at somatodendritic and terminal levels. However, somatodendritic alpha(2)-adrenoceptors that control LC firing activity are not desensitized.
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Affiliation(s)
- Y Mateo
- Department of Pharmacology, University of the Basque Country, E-48940 Leioa, Bizkaia, Spain
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