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Pedrón VT, Canero EM, Varani AP, Aon AJ, Maldonado R, Balerio GN. Baclofen prevents morphine rewarding effects and associated biochemical alterations in male and female mice. Eur J Pharmacol 2024; 979:176768. [PMID: 39002637 DOI: 10.1016/j.ejphar.2024.176768] [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] [Received: 11/29/2023] [Revised: 06/20/2024] [Accepted: 06/23/2024] [Indexed: 07/15/2024]
Abstract
Previous studies from our laboratory have shown sex differences in the behavioral, molecular, and neurochemical manifestations of morphine withdrawal and they were related to an increased sensitivity to morphine effects in males. In addition, we observed an interaction between the GABAergic and opioid systems that could also be sex-dependent. Baclofen, a GABAB receptor agonist, prevented the somatic expression and the molecular and neurochemical changes induced by morphine withdrawal syndrome in mice. On the contrary, little is known about baclofen effects in the rewarding properties of morphine in male and female mice. The present study aimed to explore the effect of baclofen (1, 2 and 3 mg/kg, i.p.) pretreatment in the rewarding effects induced by morphine (7 mg/kg, s.c.) and its effect on c-Fos and brain-derived neurotrophic factor (BDNF) expression induced by the rewarding properties of morphine in prepubertal male and female mice. Baclofen (2 mg/kg) pretreatment prevented the rewarding effects of morphine only in male mice, while baclofen (3 mg/kg) reduced these effects in both sexes. Moreover, the rewarding effects of morphine were associated with a decrease of BDNF and c-Fos expression cingulate cortex, nucleus accumbens shell, cornu ammonis 1 (CA1), and cornu ammonis 3 (CA3) areas of the hippocampus only in male mice. In addition, baclofen pretreatment prevented these changes in BDNF, but not in c-Fos expression. In conclusion, our results show that GABAB receptors have a regulatory role in the rewarding effects of morphine that could be of interest for a potential future therapeutic application in opioid use disorders.
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Affiliation(s)
- Valeria T Pedrón
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina
| | - Eliana M Canero
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Cátedra de Farmacología, Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina
| | - Andrés P Varani
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina
| | - Amira J Aon
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina
| | - Rafael Maldonado
- Laboratori de Neurofarmacologia, Facultat de Ciències de La Salut I de La Vida, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Graciela N Balerio
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Cátedra de Farmacología, Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina.
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Mandabach M, Deichmann P, Massoll A, Graves S, Assimos D, Wood K, Ness TJ. Use of Baclofen Premedication as an Analgesic Adjuvant in Patients Undergoing Percutaneous Nephrolithotripsy: A Placebo-Controlled, Double-Blind Randomized Trial. Cureus 2024; 16:e64235. [PMID: 39130904 PMCID: PMC11312425 DOI: 10.7759/cureus.64235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2024] [Indexed: 08/13/2024] Open
Abstract
INTRODUCTION Baclofen, a clinically available GABAB receptor agonist, produces nonopioid analgesia in multiple models of pain but has had limited studies related to perioperative pain control. The present study seeks to study effects of baclofen on postoperative pain measures and opioid use in adult patients subjected to percutaneous nephrolithotomy (PCNL). METHODS Using a placebo-controlled, double-blind methodology, a single 10 mg oral dose of baclofen or placebo was given prior to a surgery in 34 patients undergoing PCNL. Standardized intraoperative and postoperative protocols related to opioid use were followed. Use of postoperative opioids in the post-anesthesia care unit and for the first 24 hours following surgery were recorded as were pain scores and other medication use. RESULTS There was a significant positive correlation in the use of postoperative opioids in patients who had a preceding history of opioid use. However, there were no significant differences in opioid use which could be attributed to baclofen. There were also no differences in postoperative vital signs, side effects or other medication use. CONCLUSIONS Analgesic benefits of preoperative baclofen were not observed at the dose employed. Safety of the drug was observed.
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Affiliation(s)
- Mark Mandabach
- Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, USA
| | - Page Deichmann
- Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, USA
| | - Anthony Massoll
- Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, USA
| | - Shanna Graves
- Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, USA
| | - Dean Assimos
- Urology, University of Alabama at Birmingham, Birmingham, USA
| | - Kyle Wood
- Urology, University of Alabama at Birmingham, Birmingham, USA
| | - Timothy J Ness
- Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, USA
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Alpay B, Cimen B, Akaydin E, Onat F, Bolay H, Sara Y. Extrasynaptic δGABAA receptors mediate resistance to migraine-like phenotype in rats. J Headache Pain 2024; 25:75. [PMID: 38724972 PMCID: PMC11083752 DOI: 10.1186/s10194-024-01777-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Accepted: 04/22/2024] [Indexed: 05/12/2024] Open
Abstract
BACKGROUND GABA, a key inhibitory neurotransmitter, has synaptic and extrasynaptic receptors on the postsynaptic neuron. Background GABA, which spills over from the synaptic cleft, acts on extrasynaptic delta subunit containing GABAA receptors. The role of extrasynaptic GABAergic input in migraine is unknown. We investigated the susceptibility to valid migraine-provoking substances with clinically relevant behavioral readouts in Genetic Absence Epilepsy of Rats Strasbourg (GAERS), in which the GABAergic tonus was altered. Subsequently, we screened relevant GABAergic mechanisms in Wistar rats by pharmacological means to identify the mechanisms. METHODS Wistar and GAERS rats were administered nitroglycerin (10 mg/kg) or levcromakalim (1 mg/kg). Mechanical allodynia and photophobia were assessed using von Frey monofilaments and a dark-light box. Effects of GAT-1 blocker tiagabine (5 mg/kg), GABAB receptor agonist baclofen (2 mg/kg), synaptic GABAA receptor agonist diazepam (1 mg/kg), extrasynaptic GABAA receptor agonists gaboxadol (4 mg/kg), and muscimol (0.75 mg/kg), T-type calcium channel blocker ethosuximide (100 mg/kg) or synaptic GABAA receptor antagonist flumazenil (15 mg/kg) on levcromakalim-induced migraine phenotype were screened. RESULTS Unlike Wistar rats, GAERS exhibited no reduction in mechanical pain thresholds or light aversion following nitroglycerin or levcromakalim injection. Ethosuximide did not reverse the resistant phenotype in GAERS, excluding the role of T-type calcium channel dysfunction in this phenomenon. Tiagabine prevented levcromakalim-induced mechanical allodynia in Wistar rats, suggesting a key role in enhanced GABA spillover. Baclofen did not alleviate mechanical allodynia. Diazepam failed to mitigate levcromakalim-induced migraine phenotype. Additionally, the resistant phenotype in GAERS was not affected by flumazenil. Extrasynaptic GABAA receptor agonists gaboxadol and muscimol inhibited periorbital allodynia in Wistar rats. CONCLUSION Our study introduced a rat strain resistant to migraine-provoking agents and signified a critical involvement of extrasynaptic δGABAergic receptors. Extrasynaptic δ GABAA receptors, by mediating constant background inhibition on the excitability of neurons, stand as a novel drug target with a therapeutic potential in migraine.
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Affiliation(s)
- Berkay Alpay
- Department of Medical Pharmacology, Faculty of Medicine, Hacettepe University, Sihhiye, Ankara, 06320, Türkiye
- Neuroscience and Neurotechnology Excellence Joint Application and Research Center (NÖROM), Ankara, 06560, Türkiye
| | - Bariscan Cimen
- Department of Medical Pharmacology, Faculty of Medicine, Hacettepe University, Sihhiye, Ankara, 06320, Türkiye
- Neuroscience and Neurotechnology Excellence Joint Application and Research Center (NÖROM), Ankara, 06560, Türkiye
| | - Elif Akaydin
- Department of Medical Pharmacology, Faculty of Medicine, Hacettepe University, Sihhiye, Ankara, 06320, Türkiye
- Neuroscience and Neurotechnology Excellence Joint Application and Research Center (NÖROM), Ankara, 06560, Türkiye
| | - Filiz Onat
- Department of Medical Pharmacology, Faculty of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, 34752, Türkiye
| | - Hayrunnisa Bolay
- Neuroscience and Neurotechnology Excellence Joint Application and Research Center (NÖROM), Ankara, 06560, Türkiye.
- Department of Neurology and Algology, Faculty of Medicine, Gazi University, Besevler, Ankara, 06560, Türkiye.
| | - Yildirim Sara
- Department of Medical Pharmacology, Faculty of Medicine, Hacettepe University, Sihhiye, Ankara, 06320, Türkiye.
- Neuroscience and Neurotechnology Excellence Joint Application and Research Center (NÖROM), Ankara, 06560, Türkiye.
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Huo Y, Ma L, Zhang M, Niu M, Gu X, Zhang W, Yan M, Wei G. Development of Anticancer Peptides with Low Hemolysis, High Penetrating Membrane Activity, Certain Analgesic Activity and the Synergistic Anticancer Effect. Biomater Sci 2022; 10:1724-1741. [DOI: 10.1039/d1bm02024b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Herein, an amphiphilic cationic α-helical anticancer lipopeptide P10 with the low toxicity and high penetrating membrane activity was developed. The lipopeptide could self-assemble into stable spherical aggregates in aqueous solution,...
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Agabio R, Baldwin DS, Amaro H, Leggio L, Sinclair JMA. The influence of anxiety symptoms on clinical outcomes during baclofen treatment of alcohol use disorder: A systematic review and meta-analysis. Neurosci Biobehav Rev 2021; 125:296-313. [PMID: 33454289 DOI: 10.1016/j.neubiorev.2020.12.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 12/17/2020] [Accepted: 12/27/2020] [Indexed: 12/22/2022]
Abstract
Given the high coexistence of anxiety symptoms in people with alcohol use disorder (AUD), we aimed to determine the influence of anxiety symptoms on outcomes in patients with AUD treated with the GABAB receptor agonist baclofen. A meta-analysis of 13 comparisons (published 2010-2020) including baseline and outcome data on alcohol consumption and anxiety after 12 weeks was undertaken. There were significantly higher rates of abstinent days in patients treated with baclofen compared to placebo (p = 0.004; high certainty evidence); specifically in those with higher baseline anxiety levels (p < 0.00001; high certainty evidence) compared to those with lower baseline anxiety levels (p = 0.20; moderate certainty evidence). The change in anxiety ratings over 12 weeks did not differ between those treated with baclofen or placebo (p = 0.84; moderate certainty evidence). This may be due to different anxiety constructs being measured by scales not validated in this patient group, or that anxiety is not a biobehavioral mechanism by which baclofen may reduce alcohol drinking. Given the prevalence of anxiety symptoms in AUD all these factors warrant further research.
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Affiliation(s)
- Roberta Agabio
- Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, University of Cagliari, Italy.
| | - David S Baldwin
- Faculty of Medicine, University of Southampton, Southampton, UK; University Department of Psychiatry and Mental Health, University of Cape Town, South Africa.
| | - Hugo Amaro
- Faculty of Medicine, University of Southampton, Southampton, UK
| | - Lorenzo Leggio
- Clinical Psychoneuroendocrinology and Neuropsychopharmacology Section, Translational Addiction Medicine Branch, National Institute on Drug Abuse Intramural Research Program and National Institute on Alcohol Abuse and Alcoholism Division of Intramural Clinical and Biological Research, National Institutes of Health, Baltimore and Bethesda, MD, United States; Medication Development Program, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, MD, United States; Center for Alcohol and Addiction Studies, Department of Behavioral and Social Sciences, School of Public Health, Brown University, Providence, RI, United States; Division of Addiction Medicine, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, United States; Department of Neuroscience, Georgetown University Medical Center, Washington DC, United States.
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Ogawa Y, Irifune M, Mukai A, Shimizu Y, Doi M, Oue K, Yoshida M, Kanematsu T, Morioka N, Nakata Y, Sakai N. The indirect γ-aminobutyric acid (GABA) receptor agonist gabaculine-induced loss of the righting reflex may inhibit the descending analgesic pathway. Pharmacol Biochem Behav 2020; 198:173034. [PMID: 32910929 DOI: 10.1016/j.pbb.2020.173034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/27/2020] [Accepted: 09/02/2020] [Indexed: 10/23/2022]
Abstract
In the spinal cord, γ-aminobutyric acid (GABA) interneurons play an essential role in antinociception. However, not all actions of GABA favor antinociception at the supraspinal level. We previously reported that gabaculine, which increases endogenous GABA in the synaptic clefts, induces loss of the righting reflex (LORR) that is one indicator of hypnosis, but not immobility in response to noxious stimulus. A slow pain is transmitted to the spinal cord via C fibers and evokes substance P (SP) release from their terminals. However, the antinociceptive effects of gabaculine are still unknown. Our study examined whether the analgesic effects of the opioid morphine or the α2-adrenoceptor agonist dexmedetomidine, whose actions are mediated through facilitation of the descending analgesic pathway, are affected by gabaculine-induced LORR. We also explored the effects of GABA receptor agonists on SP release from cultured dorsal root ganglion (DRG) neurons. All drugs were administered systemically to mice. To assess antinociception, loss of nociceptive response (analgesia) and immobility were evaluated. DRG cells were dissected from rats. Gabaculine produced no analgesia. Either morphine or dexmedetomidine in combination with gabaculine induced immobility; however, the doses of each drug required to induce immobility were much higher than those required to induce analgesia. Capsaicin significantly increased SP release from DRG cells, but a high concentration (1 mM) of the GABA receptor agonist muscimol, propofol, gaboxadol, or baclofen did not inhibit the capsaicin-induced SP release, suggesting that their antinociceptive effects were not through this mechanism. Thus, the gabaculine-induced LORR may inhibit the descending analgesic pathway.
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Affiliation(s)
- Yuya Ogawa
- Section of Dental Anesthesiology, Department of Oral & Maxillofacial Surgery and Oral Medicine, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan
| | - Masahiro Irifune
- Department of Dental Anesthesiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan.
| | - Akari Mukai
- Department of Dental Anesthesiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Yoshitaka Shimizu
- Department of Dental Anesthesiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Mitsuru Doi
- Department of Dental Anesthesiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Kana Oue
- Section of Dental Anesthesiology, Department of Oral & Maxillofacial Surgery and Oral Medicine, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan
| | - Mitsuhiro Yoshida
- Section of Dental Anesthesiology, Department of Oral & Maxillofacial Surgery and Oral Medicine, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan
| | - Takashi Kanematsu
- Department of Cellular and Molecular Pharmacology, Graduate School of Biomedical and Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Norimitsu Morioka
- Department of Pharmacology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Yoshihiro Nakata
- Department of Pharmacology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Norio Sakai
- Department of Molecular and Pharmacological Neuroscience, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
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Martínez-Campos Z, Pastor N, Pineda-Urbina K, Gómez-Sandoval Z, Fernández-Zertuche M, Razo-Hernández RS. In silico structure-based design of GABA B receptor agonists using a combination of docking and QSAR. Chem Biol Drug Des 2019; 94:1782-1798. [PMID: 31207116 DOI: 10.1111/cbdd.13580] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/29/2019] [Accepted: 06/02/2019] [Indexed: 12/27/2022]
Abstract
The study of γ-aminobutyric acid B receptor (GABAB ) activation is of great interest for several brain disorders. The search of new GABAB receptor agonists has been carried out by many research groups. As a result, Baclofen has become the prototypical GABAB receptor agonist. However, several attempts have been made to modify its structure to generate derivatives with improved activity. In this work, we carried out a theoretical and computational study for a wide range of GABAB receptor agonists reported in the literature. Molecular docking and QSAR techniques were combined by using the interaction energies of the agonists with the key residues of GABAB receptor, as molecular descriptors for the QSAR construction. The resulting mathematical model suggests that the activity of GABAB receptor agonists is influenced by three factors: their shape and molecular size (PW5 and PJI2), their constitutional features (ELUMO and T(N…O)) and the energy interaction with GABAB receptor (ETRP278 ). This model was validated by the QUIK, REDUNDANCY and OVERFITTING rules, and its predicted ability was tasted by the QLOO , QASYM , R 0 2 and r m 2 rules. Finally, six new compounds are proposed (35-40) with high potential to be used as GABAB receptor agonists.
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Affiliation(s)
- Zuleyma Martínez-Campos
- Instituto de Investigación en Ciencias Básicas y Aplicadas, Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - Nina Pastor
- Instituto de Investigación en Ciencias Básicas y Aplicadas, Centro de Investigación en Dinámica Celular, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | | | | | - Mario Fernández-Zertuche
- Instituto de Investigación en Ciencias Básicas y Aplicadas, Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - Rodrigo Said Razo-Hernández
- Instituto de Investigación en Ciencias Básicas y Aplicadas, Centro de Investigación en Dinámica Celular, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
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Pedrón VT, Varani AP, Bettler B, Balerio GN. GABA B receptors modulate morphine antinociception: Pharmacological and genetic approaches. Pharmacol Biochem Behav 2019; 180:11-21. [PMID: 30851293 DOI: 10.1016/j.pbb.2019.02.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 02/28/2019] [Accepted: 02/28/2019] [Indexed: 10/27/2022]
Abstract
Previous studies in our laboratory showed an interaction between the GABAergic and opioid systems involved in the analgesic effect of baclofen (BAC). Furthermore, it is known that sex differences exist regarding various pharmacological responses of morphine (MOR) and they are related to an increased sensitivity to MOR effects in males. The aims of the present study were to evaluate the possible involvement of the GABAB receptors in the antinociceptive responses induced by MOR (1, 3 and 9 mg/kg, s.c.) administration using both pharmacological (BAC 2 mg/kg, i.p.; and 2-OH-saclofen, SAC 0.3 mg/kg, intra cisterna magna) and genetic approaches (GABAB1 knockout mice; GABAB1 KO) in mice of both sexes. In addition, we explored the alterations in c-Fos expression of different brain areas involved in the antinociceptive effect of MOR using both approaches. The pharmacological approach showed a higher dose-dependent antinociceptive effect of MOR in male mice compared to female mice. BAC and SAC pretreatment potentiated and attenuated the antinociceptive effect of MOR, respectively, in both sexes. The genetic approach revealed a dose-dependent antinociceptive effect of MOR in the wild type mice, but not in the GABAB1 KO mice and no sex differences were observed. Additionally, BAC and SAC pretreatment and the lack of GABAB1 subunit of the GABAB receptor prevented the changes observed in c-Fos expression in the cingulate cortex and nucleus accumbens of male mice. Our results suggest that the GABAB receptors are involved in the MOR antinociceptive effect of both male and female mice.
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Affiliation(s)
- Valeria T Pedrón
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Andrés P Varani
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Bernhard Bettler
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland
| | - Graciela N Balerio
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Cátedra de Farmacología, Buenos Aires, Argentina.
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9
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Sowaileh MF, Salyer AE, Roy KK, John JP, Woods JR, Doerksen RJ, Hockerman GH, Colby DA. Agonists of the γ-aminobutyric acid type B (GABA B) receptor derived from β-hydroxy and β-amino difluoromethyl ketones. Bioorg Med Chem Lett 2018; 28:2697-2700. [PMID: 29657102 PMCID: PMC6152937 DOI: 10.1016/j.bmcl.2018.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/31/2018] [Accepted: 04/02/2018] [Indexed: 01/26/2023]
Abstract
β-Hydroxy difluoromethyl ketones represent the newest class of agonists of the GABA-B receptor, and they are structurally distinct from all other known agonists at this receptor because they do not display the carboxylic acid or amino group of γ-aminobutyric acid (GABA). In this report, the design, synthesis, and biological evaluation of additional analogues of β-hydroxy difluoromethyl ketones characterized the critical nature of the substituted aromatic group on the lead compound. The importance of these new data is interpreted by docking studies using the X-ray structure of the GABA-B receptor. Moreover, we also report that the synthesis and biological evaluation of β-amino difluoromethyl ketones provided the most potent compound across these two series.
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Affiliation(s)
- Munia F Sowaileh
- Department of BioMolecular Sciences, University of Mississippi, University, MS 38677, United States
| | - Amy E Salyer
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, United States
| | - Kuldeep K Roy
- Department of BioMolecular Sciences, University of Mississippi, University, MS 38677, United States
| | - Jinu P John
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, United States
| | - James R Woods
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, United States
| | - Robert J Doerksen
- Department of BioMolecular Sciences, University of Mississippi, University, MS 38677, United States
| | - Gregory H Hockerman
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, United States
| | - David A Colby
- Department of BioMolecular Sciences, University of Mississippi, University, MS 38677, United States.
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Varani AP, Pedrón VT, Aon AJ, Höcht C, Acosta GB, Bettler B, Balerio GN. Nicotine-induced molecular alterations are modulated by GABA B receptor activity. Addict Biol 2018; 23:230-246. [PMID: 28419642 DOI: 10.1111/adb.12506] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 02/22/2017] [Accepted: 02/23/2017] [Indexed: 12/22/2022]
Abstract
It has been demonstrated that GABAB receptors modulate nicotine (NIC) reward effect; nevertheless, the mechanism implicated is not well known. In this regard, we evaluated the involvement of GABAB receptors on the behavioral, neurochemical, biochemical and molecular alterations associated with the rewarding effects induced by NIC in mice, from a pharmacological and genetic approach. NIC-induced rewarding properties (0.5 mg/kg, subcutaneously, sc) were evaluated by conditioned place preference (CPP) paradigm. CPP has three phases: preconditioning, conditioning and postconditioning. GABAB receptor antagonist 2-hydroxysaclofen (0.25, 0.5 and 1 mg/kg; intraperitoneally, ip) or the GABAB receptor agonist baclofen (3 mg/kg; ip) was injected before NIC during the conditioning phase. GABAB1 knockout (GABAB1 KO) mice received NIC during the conditioning phase. Vehicle and wild-type controls were employed. Neurochemical (dopamine, serotonin and their metabolites), biochemical (nicotinic receptor α4β2, α4β2nAChRs) and molecular (c-Fos) alterations induced by NIC were analyzed after the postconditioning phase by high-performance liquid chromatography (HPLC), receptor-ligand binding assays and immunohistochemistry, respectively, in nucleus accumbens (Acb), prefrontal cortex (PFC) and ventral tegmental area (VTA). NIC induced rewarding effects in the CPP paradigm and increased dopamine levels in Acb and PFC, α4β2nAChRs density in VTA and c-Fos expression in Acb shell (AcbSh), VTA and PFC. We showed that behavioral, neurochemical, biochemical and molecular alterations induced by NIC were prevented by baclofen. However, in 2-hydroxysaclofen pretreated and GABAB1 KO mice, these alterations were potentiated, suggesting that GABAB receptor activity is necessary to control alterations induced by NIC-induced rewarding effects. Therefore, the present findings provided important contributions to the mechanisms implicated in NIC-induced rewarding effects.
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Affiliation(s)
- Andres P Varani
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Valeria T Pedrón
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Amira J Aon
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Christian Höcht
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Cátedra de Farmacología, Buenos Aires, Argentina
| | - Gabriela B Acosta
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
| | - Bernhard Bettler
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, University of Basel, Switzerland
| | - Graciela N Balerio
- CONICET - Universidad de Buenos Aires, Instituto de Investigaciones Farmacológicas (ININFA), Buenos Aires, Argentina
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Cátedra de Farmacología, Buenos Aires, Argentina
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Kannampalli P, Poli SM, Boléa C, Sengupta JN. Analgesic effect of ADX71441, a positive allosteric modulator (PAM) of GABA B receptor in a rat model of bladder pain. Neuropharmacology 2017; 126:1-11. [PMID: 28823612 DOI: 10.1016/j.neuropharm.2017.08.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 07/26/2017] [Accepted: 08/16/2017] [Indexed: 01/12/2023]
Abstract
Therapeutic use of GABAB receptor agonists for conditions like chronic abdominal pain, overactive bladder (OAB) and gastroesophageal reflux disease (GERD) is severely affected by poor blood-brain barrier permeability and potential side effects. ADX71441 is a novel positive allosteric modulator (PAM) of the GABAB receptor that has shown encouraging results in pre-clinical models of anxiety, pain, OAB and alcohol addiction. The present study investigates the analgesic effect of ADX71441 to noxious stimulation of the urinary bladder and colon in rats. In female Sprague-Dawley rats, systemic (i.p), but not intrathecal (i.t), administration of ADX71441 produced a dose-dependent decrease in viscero-motor response (VMR) to graded urinary bladder distension (UBD) and colorectal distension (CRD). Additionally, intra-cerebroventricular (i.c.v.) administration of ADX71441 significantly decreased the VMRs to noxious UBD. In electrophysiology experiments, the drug did not attenuate the responses of UBD-sensitive pelvic nerve afferent (PNA) fibers to UBD. In contrast, ADX71441 significantly decreased the responses of UBD-responsive lumbosacral (LS) spinal neurons in spinal intact rats. However, ADX71441 did not attenuate these LS neurons in cervical (C1-C2) spinal transected rats. During cystometrogram (CMG) recordings, ADX71441 (i.p.) significantly decreased the VMR to slow infusion without affecting the number of voiding contraction. These results indicate that ADX71441 modulate bladder nociception via its effect at the supra-spinal sites without affecting the normal bladder motility and micturition reflex in naïve adult rats.
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Affiliation(s)
- Pradeep Kannampalli
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Sonia-Maria Poli
- Addex Therapeutics, 14 Chemin des Aulx, CH-1228 Plan-les-Ouates, Geneva, Switzerland
| | - Christelle Boléa
- Addex Therapeutics, 14 Chemin des Aulx, CH-1228 Plan-les-Ouates, Geneva, Switzerland
| | - Jyoti N Sengupta
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Pediatric Gastroenterology, Medical College of Wisconsin, Milwaukee, WI, USA.
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Fung T, Asiri YI, Wall R, Schwarz SKW, Puil E, MacLeod BA. Variations of isovaline structure related to activity in the formalin foot assay in mice. Amino Acids 2017; 49:1203-1213. [PMID: 28432424 DOI: 10.1007/s00726-017-2421-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 04/10/2017] [Indexed: 01/25/2023]
Abstract
Current centrally acting analgesics such as opioids are associated with adverse effects that limit their use and threaten patient safety. Isovaline is a novel prototype analgesic that produces peripheral antinociception in several pain models with little or no effect on the central nervous system. The aim of this study was to establish a preliminary structure-activity relationship for isovaline derivatives by assaying efficacy in the formalin foot assay and central adverse effect profile in mice. Selected compounds were tested using the formalin foot assay to determine efficacy in reducing formalin-induced behaviors. Of the compounds tested, R-isovaline, S-isovaline, and 1-amino-1-cyclobutanecarboxylic acid reduced nocifensive behavior in phase II of the assay. These effects occurred without affecting performance on the rotarod, indicating that the reduction in nocifensive behaviors was not due to sedation or motor incoordination. Modifications to isovaline that increased its steric size without a cyclobutane ring formation produced compounds with no activity in the formalin foot assay. These findings indicate that the conformational stability of isovaline or the ability to form a cyclobutane ring is necessary for activity in the formalin foot assay.
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Affiliation(s)
- Timothy Fung
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Yahya I Asiri
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Richard Wall
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Stephan K W Schwarz
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.,Department of Anesthesia, Providence Health Care/St. Paul's Hospital, Vancouver, BC, V6Z 1Y6, Canada
| | - Ernest Puil
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Bernard A MacLeod
- Department of Anesthesiology, Pharmacology & Therapeutics, Hugill Anesthesia Research Centre, The University of British Columbia, 2176 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
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Central GABAA receptors are involved in inflammatory and cardiovascular consequences of endotoxemia in conscious rats. Naunyn Schmiedebergs Arch Pharmacol 2015; 389:279-88. [PMID: 26685896 DOI: 10.1007/s00210-015-1201-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 12/14/2015] [Indexed: 02/06/2023]
Abstract
γ-Aminobutyric acid (GABA), the principal brain inhibitory neurotransmitter, modulates inflammatory and neurodegenerative disease. Here, we tested the hypothesis that central GABAergic neurotransmission mediates the detrimental inflammatory, hemodynamic, and cardiac autonomic actions of endotoxemia. The effects of drugs that block GABA receptors or interfere with GABA uptake or degradation on blood pressure (BP), heart rate (HR), and HR variability (HRV) responses elicited by i.v. lipopolysaccharide (LPS) were assessed in conscious rats. The hypotensive effect of LPS (10 mg/kg) was blunted after intracisternal (i.c.) administration of bicuculline (GABAA receptor antagonist) or saclofen (GABAB receptor antagonist). By contrast, the concomitant LPS-evoked tachycardia and decreases in time domain and frequency domain indices of HRV (measures of cardiac autonomic control) were abolished upon treatment with bicuculline but not saclofen. Increases in serum tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) caused by LPS disappeared in the presence of bicuculline or saclofen, whereas LPS-evoked increases in serum nitric oxide metabolites (NOx) were counteracted by bicuculline only. None of the endotoxemia effects was altered in rats treated with i.c. tiagabine (GABA reuptake inhibitor) or vigabatrin (GABA transaminase inhibitor). These data suggest a major role for central GABAA receptors in the inflammatory and cardiovascular effects of endotoxemia.
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Brown KM, Roy KK, Hockerman GH, Doerksen RJ, Colby DA. Activation of the γ-Aminobutyric Acid Type B (GABA(B)) Receptor by Agonists and Positive Allosteric Modulators. J Med Chem 2015; 58:6336-47. [PMID: 25856547 DOI: 10.1021/jm5018913] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Since the discovery of the GABA(B) agonist and muscle relaxant baclofen, there have been substantial advancements in the development of compounds that activate the GABA(B) receptor as agonists or positive allosteric modulators. For the agonists, most of the existing structure-activity data apply to understanding the role of substituents on the backbone of GABA as well as replacing the carboxylic acid and amine groups. In the cases of the positive allosteric modulators, the allosteric binding site(s) and structure-activity relationships are less well-defined; however, multiple classes of molecules have been discovered. The recent report of the X-ray structure of the GABA(B) receptor with bound agonists and antagonists provides new insights for the development of compounds that bind the orthosteric site of this receptor. From a therapeutic perspective, these data have enabled efforts in drug discovery in areas of addiction-related behavior, the treatment of anxiety, and the control of muscle contractility.
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Affiliation(s)
- Katie M Brown
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University , West Lafayette, Indiana 47907, United States
| | - Kuldeep K Roy
- Department of Biomolecular Sciences, University of Mississippi , University, Mississippi 38677, United States
| | - Gregory H Hockerman
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University , West Lafayette, Indiana 47907, United States
| | - Robert J Doerksen
- Department of Biomolecular Sciences, University of Mississippi , University, Mississippi 38677, United States
| | - David A Colby
- Department of Biomolecular Sciences, University of Mississippi , University, Mississippi 38677, United States
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Huynh TG, Cuny H, Slesinger PA, Adams DJ. Novel Mechanism of Voltage-Gated N-type (Cav2.2) Calcium Channel Inhibition Revealed through α-Conotoxin Vc1.1 Activation of the GABAB Receptor. Mol Pharmacol 2014; 87:240-50. [DOI: 10.1124/mol.114.096156] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Varani AP, Aso E, Maldonado R, Balerio GN. Baclofen and 2-hydroxysaclofen modify acute hypolocomotive and antinociceptive effects of nicotine. Eur J Pharmacol 2014; 738:200-5. [DOI: 10.1016/j.ejphar.2014.05.039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 05/21/2014] [Accepted: 05/22/2014] [Indexed: 11/28/2022]
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Varani AP, Moutinho Machado L, Balerio GN. Baclofen prevented the changes in c-Fos and brain-derived neutrophic factor expressions during mecamylamine-precipitated nicotine withdrawal in mice. Synapse 2014; 68:508-17. [DOI: 10.1002/syn.21763] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 06/12/2014] [Accepted: 06/30/2014] [Indexed: 12/13/2022]
Affiliation(s)
- Andrés P. Varani
- Instituto de Investigaciones Farmacológicas (UBA-CONICET); Junín 956, 5° piso, (C1113AAD) Buenos Aires Argentina
| | - Lirane Moutinho Machado
- Instituto de Investigaciones Farmacológicas (UBA-CONICET); Junín 956, 5° piso, (C1113AAD) Buenos Aires Argentina
| | - Graciela N. Balerio
- Instituto de Investigaciones Farmacológicas (UBA-CONICET); Junín 956, 5° piso, (C1113AAD) Buenos Aires Argentina
- Cátedra de Farmacología; Facultad de Farmacia y Bioquímica; Universidad de Buenos Aires; Junín 956 5° Piso, (C1113AAD) Buenos Aires Argentina
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Varani AP, Aso E, Moutinho LM, Maldonado R, Balerio GN. Attenuation by baclofen of nicotine rewarding properties and nicotine withdrawal manifestations. Psychopharmacology (Berl) 2014; 231:3031-40. [PMID: 24553576 DOI: 10.1007/s00213-014-3469-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 01/29/2014] [Indexed: 11/28/2022]
Abstract
RATIONALE Nicotine is a major active ingredient in tobacco and plays a major role in tobacco addiction. In rodents, repeated nicotine administration produces behavioral responses related to its addictive properties, such as reinforcing effects and physical dependence. OBJECTIVES The aim of the present study was to evaluate the possible role of GABAB receptor in responses induced by repeated nicotine administration in Swiss Webster mice. RESULTS Nicotine hydrogen tartrate salt (0.5 mg/kg, s.c.) administration induced rewarding properties in the conditioning place preference test. The GABAB receptor agonist, baclofen (3 mg/kg, i.p.) abolished the rewarding properties induced by nicotine hydrogen tartrate salt (0.5 mg/kg, s.c.). In addition, naloxone-precipitated nicotine withdrawal induced somatic manifestations, anxiety-like effects in the elevated plus maze test and dysphoric manifestations in the conditioned place aversion paradigm. Baclofen (2 and 3 mg/kg, i.p.) prevented the somatic manifestations and the anxiety-like effects associated with naloxone-precipitated nicotine withdrawal but not the dysphoric manifestations. CONCLUSIONS These results showed that nicotine rewarding properties and negative aspects of nicotine withdrawal, such as anxiety-like effects and somatic manifestations, can be modulated by the GABAB receptor activity. This study now reveals a novel possible application of baclofen to develop new therapeutic strategies to achieve smoking cessation.
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Affiliation(s)
- Andrés P Varani
- Instituto de Investigaciones Farmacológicas (CONICET), Junín 956 5° Piso, Buenos Aires, C1113AAD, Argentina
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Varani AP, Antonelli MC, Balerio GN. Mecamylamine-precipitated nicotine withdrawal syndrome and its prevention with baclofen: an autoradiographic study of α4β2 nicotinic acetylcholine receptors in mice. Prog Neuropsychopharmacol Biol Psychiatry 2013; 44:217-25. [PMID: 23500668 DOI: 10.1016/j.pnpbp.2013.02.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 02/13/2013] [Accepted: 02/27/2013] [Indexed: 11/26/2022]
Abstract
A previous study from our laboratory showed that baclofen (BAC, GABAB receptor agonist) was able to prevent the behavioral expression of nicotine (NIC) withdrawal syndrome. To further investigate the mechanisms underlying this effect, we conducted this study, with the aims of analyzing α4β2 nicotinic receptor density during NIC withdrawal and, in case we found any changes, of determining whether they could be prevented by pretreatment with BAC. Swiss Webster albino mice received NIC (2.5 mg/kg, s.c.) 4 times daily, for 7 days. On the 8th day, NIC-treated mice received the nicotinic antagonist mecamylamine (MEC; 2 mg/kg, i.p.) 1 h after the last dose of NIC. A second group of NIC-treated mice received BAC (2 mg/kg, i.p.) prior to MEC administration. Thirty minutes after MEC, mice were sacrificed and brain autoradiography with [(3)H]epibatidine was carried out at five different anatomical levels. Autoradiographic mapping showed a significant increase of α4β2 nicotinic receptor labeling during NIC withdrawal in the nucleus accumbens shell (AcbSh), medial habenular nucleus (HbM), thalamic nuclei, dorsal lateral geniculate (DLG) nucleus, fasciculus retroflexus (fr), ventral tegmental area, interpeduncular nucleus and superior colliculus. BAC pretreatment prevented the increased α4β2 nicotinic receptor binding sites in the AcbSh, MHb, thalamic nuclei, DLG nucleus and fr. The present results suggest a relationship between BAC's preventive effect of the expression of NIC withdrawal signs, and its ability to restore the changes in α4β2 nicotinic receptor labeling, evidenced in specific brain areas in NIC withdrawn animals.
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Affiliation(s)
- Andrés P Varani
- Instituto de Investigaciones Farmacológicas (UBA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina
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20
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Li X, Risbrough VB, Cates-Gatto C, Kaczanowska K, Finn MG, Roberts AJ, Markou A. Comparison of the effects of the GABAB receptor positive modulator BHF177 and the GABAB receptor agonist baclofen on anxiety-like behavior, learning, and memory in mice. Neuropharmacology 2013; 70:156-67. [PMID: 23376712 PMCID: PMC3644349 DOI: 10.1016/j.neuropharm.2013.01.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 01/02/2013] [Accepted: 01/12/2013] [Indexed: 12/14/2022]
Abstract
γ-Aminobutyric acid B (GABAB) receptor activation is a potential therapeutic approach for the treatment of drug addiction, pain, anxiety, and depression. However, full agonists of this receptor induce side-effects, such as sedation, muscle relaxation, tolerance, and cognitive disruption. Positive allosteric modulators (PAMs) of the GABAB receptor may have similar therapeutic effects as agonists with superior side-effect profiles. The present study behaviorally characterized N-([1R,2R,4S]-bicyclo[2.2.1]hept-2-yl)-2-methyl-5-(4-[trifluoromethyl]phenyl)-4-pyrimidinamine (BHF177), a GABAB receptor PAM, in mouse models of anxiety-like behavior, learning and memory. In addition, the effects of BHF177 were compared with the agonist baclofen. Unlike the anxiolytic chlordiazepoxide, baclofen (0.5, 1.5, and 2.5 mg/kg, intraperitoneally) and BHF177 (10, 20, and 40 mg/kg, orally) had no effect on anxiety-like behavior in the elevated plus maze, light/dark box, or Vogel conflict test. Baclofen increased punished drinking in the Vogel conflict test, but this effect may be attributable to the analgesic actions of baclofen. At the highest dose tested (2.5 mg/kg), baclofen-treated mice exhibited sedation-like effects (i.e., reduced locomotor activity) across many of the tests, whereas BHF177-treated mice exhibited no sedation-like effects. BHF177 exhibited pro-convulsion properties only in mice, but not in rats, indicating that this effect may be species-specific. At doses that were not sedative or pro-convulsant, baclofen and BHF177 had no selective effects on fear memory retrieval in contextual and cued fear conditioning or spatial learning and memory in the Barnes maze. These data suggest that BHF177 has little sedative activity, no anxiolytic-like profile, and minimal impairment of learning and memory in mice.
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Affiliation(s)
- Xia Li
- Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Victoria B. Risbrough
- Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, CA, USA
- Veterans Affairs Center of Excellence for Stress and Mental Health, La Jolla, CA, USA
| | - Chelsea Cates-Gatto
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, La Jolla, CA, USA
| | | | - M. G. Finn
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Amanda J Roberts
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, La Jolla, CA, USA
| | - Athina Markou
- Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, CA, USA
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Varani AP, Balerio GN. GABAB receptors involvement in the effects induced by nicotine on anxiety-related behaviour in mice. Pharmacol Res 2012; 65:507-13. [DOI: 10.1016/j.phrs.2012.03.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 03/01/2012] [Accepted: 03/02/2012] [Indexed: 01/06/2023]
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Chen SH, Tsai YJ, Lin CT, Wang HY, Li SF, Lue JH. Changes in GABA and GABA(B) receptor expressions are involved in neuropathy in the rat cuneate nucleus following median nerve transection. Synapse 2012; 66:561-72. [PMID: 22290688 DOI: 10.1002/syn.21539] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 01/20/2012] [Indexed: 01/17/2023]
Abstract
This study examined the relationship between changes in GABA transmission and behavioral abnormalities after median nerve transection. Following unilateral median nerve transection, the percentage of GABA-like immunoreactive neurons in the cuneate nucleus and that of GABA(B) receptor-like immunoreactive neurons in the dorsal root ganglion in the injured side decreased and reached a nadir at 4 weeks after median nerve transection. Four weeks after bilateral median nerve transection and intraperitoneal application with saline, baclofen (2 mg kg⁻¹), or phaclofen (2 mg kg⁻¹) before unilateral electrical stimulation of the injured median nerve, we investigated the level of neuropeptide Y release and c-Fos expression in the stimulated side of the cuneate nucleus. The neuropeptide Y release level and the number of c-Fos-like immunoreactive neurons in the baclofen group were significantly attenuated, whereas those in the phaclofen group had increased compared to the saline group. These findings indicate that median nerve transection reduces GABA transmission, promoting injury-induced neuropeptide Y release and consequently evoking c-Fos expression in cuneate nucleus neurons. Furthermore, this study used the CatWalk method to assess behavioral abnormalities in rats following median nerve transection. These abnormalities were reversed by baclofen treatment. Overall, the results suggest that baclofen treatment block neuropeptide Y release, subsequently lessening c-Fos expression in cuneate neurons and consequently attenuating neuropathic signal transmission to the thalamus.
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Affiliation(s)
- Seu-Hwa Chen
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei 10018, Taiwan, Republic of China
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Varani AP, Moutinho LM, Calvo M, Balerio GN. Ability of baclofen to prevent somatic manifestations and neurochemical changes during nicotine withdrawal. Drug Alcohol Depend 2011; 119:e5-12. [PMID: 21733642 DOI: 10.1016/j.drugalcdep.2011.05.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 05/14/2011] [Accepted: 05/15/2011] [Indexed: 10/18/2022]
Abstract
BACKGROUND Nicotine (NIC), the major active component of tobacco, is critical in the maintenance of the smoking habit. The aims of the present study were to analyze the behavioural and neurochemical variations during NIC withdrawal syndrome in mice, and whether they are prevented with baclofen (BAC, GABA(B) receptor agonist). METHODS Swiss-Webster albino mice received NIC (2.5 mg/kg, s.c.) 4 times daily, for 7 consecutive days. On day 8 (the day of the experiment), NIC-treated mice received the nicotine antagonist mecamylamine (MEC, 2 mg/kg, i.p.) 1h after the last dose of NIC. A second group of dependent mice received BAC (2mg/kg, i.p.) before MEC-precipitated abstinence. The somatic signs were measured for 30 min. Dopamine (DA), serotonin (5-hydroxytryptamine; 5-HT) and its metabolites concentrations were determined by HPLC in the striatum, cortex and hippocampus. RESULTS The global score was greater in the abstinent group compared to the control group. Moreover, the global score time course showed a higher increase at 10 min compared to the global score at 5 min or 30 min after MEC-precipitated NIC withdrawal. In addition, the global score was attenuated by BAC. The DA and dihydroxyphenyl acetic acid (DOPAC) cortical levels decreased in the abstinent group, while BAC reestablished these levels 10 min after NIC withdrawal. Furthermore, DA and 5-HT striatal levels decreased during NIC withdrawal, and BAC reverted this decrease. CONCLUSION In conclusion, the prevention of NIC withdrawal signs by BAC could be related to changes in dopaminergic and serotonergic activity.
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Affiliation(s)
- Andrés P Varani
- Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Piso, Buenos Aires C1113AAD, Argentina
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Lee IO, Son JK, Lim ES, Kim YS. Pharmacology of intracisternal or intrathecal glycine, muscimol, and baclofen in strychnine-induced thermal hyperalgesia of mice. J Korean Med Sci 2011; 26:1371-7. [PMID: 22022192 PMCID: PMC3192351 DOI: 10.3346/jkms.2011.26.10.1371] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 08/10/2011] [Indexed: 11/30/2022] Open
Abstract
Glycine and γ-aminobutyric acid (GABA) are localized and released by the same interneurons in the spinal cord. Although the effects of glycine and GABA on analgesia are well known, little is known about the effect of GABA in strychnine-induced hyperalgesia. To investigate the effect of GABA and the role of the glycine receptor in thermal hyperalgesia, we designed an experiment involving the injection of muscimol (a GABA(A) receptor agonist), baclofen (a GABA(B) receptor agonist) or glycine with strychnine (strychnine sensitive glycine receptor antagonist). Glycine, muscimol, or baclofen with strychnine was injected into the cisterna magna or lumbar subarachnoidal spaces of mice. The effects of treatment on strychnine-induced heat hyperalgesia were observed using the pain threshold index via the hot plate test. The dosages of experimental drugs and strychnine we chose had no effects on motor behavior in conscious mice. Intracisternal or intrathecal administration of strychnine produced thermal hyperalgesia in mice. Glycine antagonize the effects of strychnine, whereas, muscimol or baclofen does not. Our results indicate that glycine has anti-thermal hyperalgesic properties in vivo; and GABA receptor agonists may lack the binding abilities of glycine receptor antagonists with their sites in the central nervous system.
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Affiliation(s)
- Il Ok Lee
- Department of Anesthesiology and Pain Medicine, College of Medicine, Korea University, Seoul, Korea.
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Li YQ, Li H, Wei J, Qu L, Wu LA. Expression changes of K+-Cl- co-transporter 2 and Na+-K+-Cl- co-transporter1 in mouse trigeminal subnucleus caudalis following pulpal inflammation. Brain Res Bull 2010; 81:561-4. [PMID: 20067823 DOI: 10.1016/j.brainresbull.2010.01.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 12/23/2009] [Accepted: 01/06/2010] [Indexed: 10/20/2022]
Abstract
Cation chloride co-transporters, including K(+)-Cl(-) co-transporter 2 (KCC2) and Na(+)-K(+)-Cl(-) co-transporter 1 (NKCC1), are of particular importance to GABAergic transmission and thus involved in the development of hyperalgesia at the spinal level. However, it is largely unknown whether these co-transporters in the trigeminal system contribute to dental pain. In this study, we investigated the expression of KCC2 and NKCC1 mRNAs in mouse trigeminal subnucleus caudalis (Vc) after lipopolysaccharide (LPS) application to the tooth pulp by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) method. KCC2 mRNA was found to be down-regulated at 1d after pulpal inflammation, while NKCC1 was up-regulated. Blockade of endogenous brain-derived neurotrophic factor-tyrosine receptor kinase B pathway with K252a produced pronounced antinociception as evidenced by decreased tongue protrusion behavior in LPS-treated mice. These data suggest that KCC2 and NKCC1 in Vc may play a critical role in the nociception and transmission of dental pain during pulpal inflammation.
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Affiliation(s)
- Yong-Qi Li
- Comprehensive Diagnostic and Therapeutic Center, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
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Miranda F, Jiménez JC, Cedillo LN, Sandoval-Sánchez A, Millán-Mejía P, Sánchez-Castillo H, Velázquez-Martínez DN. The GABA-B antagonist 2-hydroxysaclofen reverses the effects of baclofen on the discriminative stimulus effects of d-amphetamine in the conditioned taste aversion procedure. Pharmacol Biochem Behav 2009; 93:25-30. [DOI: 10.1016/j.pbb.2009.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Revised: 03/24/2009] [Accepted: 04/02/2009] [Indexed: 10/20/2022]
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Wu LA, Huang J, Wang W, Wang W, Wang XJ, Wu SX. Down-regulation of K+ -Cl- co-transporter 2 in mouse medullary dorsal horn contributes to the formalin-induced inflammatory orofacial pain. Neurosci Lett 2009; 457:36-40. [PMID: 19429157 DOI: 10.1016/j.neulet.2009.03.107] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 03/28/2009] [Accepted: 03/30/2009] [Indexed: 11/30/2022]
Abstract
Cation chloride co-transporters, including K(+)-Cl(-) co-transporter 2 (KCC2) and Na(+)-K(+)-Cl(-) co-transporter 1 (NKCC1), are of particular importance to GABAergic transmission and thus involved in the development of hyperalgesia at the spinal level. However, there are fewer relevant reports in the trigeminal system. In this study, we investigated the behavioral changes and the accompanying change in the expressions of KCC2 and NKCC1 mRNAs in mouse medullary dorsal horn (MDH) after subcutaneous injection of formalin into the left vibrissa pad. Furthermore, we observed the behavioral changes following intracisternal injection of KCC2 antisense oligodeoxynucleotides (ASO) into naïve mice. Subcutaneous injection of formalin-induced a significant increase in the number of face rubbing events which are the indicators of spontaneous pain. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) results indicated that, compared to the saline control or the contralateral side, the ipsilateral mRNA level of KCC2 but not NKCC1, was significantly reduced in formalin-injected mice during phase 1 observation, followed by gradual recovery. Intracisternal injection of KCC2 ASO into naïve mice led to behavioral hypersensitivity similar to the hyperalgesia observed in formalin experiments. These findings indicate that peripheral inflammation induces down-regulation of KCC2 in the MDH, which may in turn facilitate the development of acute inflammatory pain. These results also suggest that preventing the down-regulation of KCC2 is a possible way to combat orofacial pain.
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Affiliation(s)
- Li-An Wu
- Department of Paediatric Dentistry, School of Stomatology, Fourth Military Medical University, No. 145 West Changle Road, Xi'an, China
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28
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5-(4-Chlorophenyl)-5,6-dihydro-1,3-oxazepin-7(4H)-one derivatives as lipophilic cyclic analogues of baclofen: Design, synthesis, and neuropharmacological evaluation. Bioorg Med Chem 2008; 16:7983-91. [DOI: 10.1016/j.bmc.2008.07.064] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2008] [Revised: 07/22/2008] [Accepted: 07/23/2008] [Indexed: 11/23/2022]
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Barbaresi P. Cellular and subcellular localization of the GABAB receptor 1a/b subunit in the rat periaqueductal gray matter. J Comp Neurol 2007; 505:478-92. [DOI: 10.1002/cne.21509] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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30
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Injection of recombinant human sulfamidase into the CSF via the cerebellomedullary cistern in MPS IIIA mice. Mol Genet Metab 2006; 90:313-28. [PMID: 17166757 DOI: 10.1016/j.ymgme.2006.10.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 10/18/2006] [Accepted: 10/18/2006] [Indexed: 10/23/2022]
Abstract
At present, there is no widely available, safe and effective treatment for lysosomal storage disorders (LSD) that affect the brain. We have used a naturally occurring mouse model of mucopolysaccharidosis type IIIA (MPS IIIA) or Sanfilippo syndrome, to evaluate the effect of repeated injection of recombinant human sulfamidase (rhSGSH) into the cerebrospinal fluid via the cisterna magna (CM) on central nervous system (CNS) pathology and behavioral function. Mice received up to seven injections of rhSGSH (5-20 microg rhSGSH per injection) or vehicle on a fortnightly or monthly basis. A dose-dependent reduction in the level of a heparan sulfate-derived monosulfated disaccharide was observed within the brain (up to 62% reduction compared with vehicle-treated MPS IIIA mice) and spinal cord (up to 71% reduction). Ultrastructural examination revealed a reduction in lysosomal vesicle formation in various cell types and fewer (ubiquitin-positive) axonal spheroids were observed in several brain regions. The biochemical changes were accompanied by improved behavior, particularly in mice-treated more frequently. A humoral immune response to rhSGSH was observed in treated animals. Intra-CM injection of lysosomal enzyme may therefore represent an immediately applicable method of treating the CNS effects of this and potentially other LSD that affect the brain.
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Reis GML, Duarte IDG. Baclofen, an agonist at peripheral GABAB receptors, induces antinociception via activation of TEA-sensitive potassium channels. Br J Pharmacol 2006; 149:733-9. [PMID: 17016510 PMCID: PMC2014648 DOI: 10.1038/sj.bjp.0706898] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND AND PURPOSE Central anti-nociceptive actions of baclofen involve activation of K+ channels. Here we assessed what types of K+ channel might participate in the peripheral anti-nociception induced by baclofen. EXPERIMENTAL APPROACH Nociceptive thresholds to mechanical stimulation in rat paws treated with intraplantar prostaglandin E2.(PGE2) to induce hyperalgesia were measured 3 h after PGE2 injection. Other agents were also given by intraplantar injection. KEY RESULTS Baclofen elicited a dose-dependent (15 - 240 microg per paw) anti-nociceptive effect. An intermediate dose of baclofen (60 microg) did not produce antinociception in the contralateral paw, showing its peripheral site of action. The GABAB receptor antagonist saclofen (12.5 - 100 microg per paw) antagonized, in a dose-dependent manner, peripheral antinociception induced by baclofen (60 microg), suggesting a specific effect. This antinociceptive action of baclofen was unaffected by bicuculline, GABAA receptor antagonist (80 microg per paw), or by (1,2,5,6 tetrahydropyridin-4-yl) methylphosphinic acid, GABAC receptor antagonist (20 microg per paw). The peripheral antinociception induced by baclofen (60 microg) was reversed, in a dose-dependent manner, by the voltage-dependent K+ channel blockers tetraethylammonium (7.5 - 30 microg per paw) and 4-aminopyridine (2.5 - 10 microg per paw). The blockers of other K+ channels, glibenclamide (160 microg), tolbutamide (320 microg), charybdotoxin (2 microg), dequalinium (50 microg) and caesium (500 microg) had no effect. CONCLUSIONS AND IMPLICATIONS This study provides evidence that the peripheral antinociceptive effect of the GABAB receptor agonist baclofen results from the activation of tetraethylammonium-sensitive K+ channels. Other K+ channels appear not to be involved.
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Affiliation(s)
- G M L Reis
- Department of Pharmacology, Institute of Biological Sciences, UFMG Belo Horizonte, Minas Gerais, Brazil
| | - I D G Duarte
- Department of Pharmacology, Institute of Biological Sciences, UFMG Belo Horizonte, Minas Gerais, Brazil
- Author for correspondence:
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Potes CS, Neto FL, Castro-Lopes JM. Inhibition of pain behavior by GABAB receptors in the thalamic ventrobasal complex: Effect on normal rats subjected to the formalin test of nociception. Brain Res 2006; 1115:37-47. [PMID: 16938274 DOI: 10.1016/j.brainres.2006.07.089] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2005] [Revised: 07/14/2006] [Accepted: 07/24/2006] [Indexed: 11/25/2022]
Abstract
The ventrobasal complex of the thalamus (VB) participates in the transmission and modulation of noxious information. Recent data suggested that GABA(B) receptors in the VB might be involved in the modulation of neuronal activity in response to chronic noxious input. However, in acute inflammatory pain, the role of GABA(B) receptors in the VB remains unknown. The formalin test of nociception was performed in rats stereotaxically injected in the VB contralateral to the formalin-injected paw, with saline (controls), baclofen (0.5 and 0.875 microg), a specific GABA(B) receptor agonist or CGP35348 (25 microg), a GABA(B) receptor antagonist. Control animals exhibited phase 1 (acute pain) and phase 2 (tonic pain) nociception-related activities as previously described. The higher dose of baclofen induced a significant decrease of all pain-related behaviors in both phases of the test and had no observable effects on the animals' motor function, while the lower dose could not reduce the total pain-related activities. Injection of CGP35348 prior to baclofen reduced the antinociceptive effect caused by baclofen during phase 2 in the paw-jerks and in total pain-related activities. CGP35348 alone had antinociceptive effects in both phases, though less pronounced than baclofen 0.875 microg in the total pain-related activities during phase 2. Data demonstrate that both the blockade and the activation of GABA(B) receptors in the VB of rats induce antinociception in acute and tonic pain. An important role for GABA(B) receptors on the thalamic processing of nociceptive input in the VB is suggested.
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Affiliation(s)
- Catarina Soares Potes
- Institute of Histology and Embryology, Faculty of Medicine and IBMC, University of Porto, 4200-319 Porto, Portugal
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Potes CS, Neto FL, Castro-Lopes JM. Administration of baclofen, a γ-aminobutyric acid type B agonist in the thalamic ventrobasal complex, attenuates allodynia in monoarthritic rats subjected to the ankle-bend test. J Neurosci Res 2006; 83:515-23. [PMID: 16400658 DOI: 10.1002/jnr.20737] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
gamma-Aminobutyric acid type B (GABAB) receptors are involved in the modulation of neuronal activity in response to chronic noxious input. However, the effect of their activation in chronic inflammatory pain in relay thalamic nuclei such as the ventrobasal complex (VB) is not known. In this study, experimental groups of 2, 4, and 14 days monoarthritic (MA) rats were injected with saline (controls) or baclofen (0.875 microg), a specific GABAB receptor agonist, in the VB contralateral to the inflamed joint, and the ankle-bend test was performed. Ankle-bend scores in control animals were near the maximum and were rather constant throughout the entire experimental period, indicating severe nociception. The same was observed in 2 days MA rats injected with baclofen. In the 4 days MA group, the response to baclofen injection was inconsistent among different animals, whereas, in 14 days MA rats, baclofen caused clear antinociceptive effects. Additionally, a 0.5 microg dose of baclofen was tested in 14 days MA rats, but no effect was observed, whereas a 1.25 mug dose produced visible side effects. Baclofen injections that did not target the VB but reached neighboring nuclei were ineffective in reducing nociception. Data demonstrate that the activation of the GABAB receptors by baclofen in the VB of MA rats leads to a decrease of nociception. Moreover, the response depends on the time course of the disease, suggesting the occurrence of different excitatory states of thalamic VB neurons. In conclusion, GABAB receptors in the VB play an important role in chronic inflammatory pain processing.
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Affiliation(s)
- Catarina Soares Potes
- Institute of Histology and Embryology, Faculty of Medicine and IBMC, University of Porto, Porto, Portugal
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Binet V, Goudet C, Brajon C, Le Corre L, Acher F, Pin JP, Prézeau L. Molecular mechanisms of GABAB receptor activation: new insights from the mechanism of action of CGP7930, a positive allosteric modulator. Biochem Soc Trans 2004; 32:871-2. [PMID: 15494037 DOI: 10.1042/bst0320871] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The GABAB (γ-aminobutyric acid-B) receptor is composed of two subunits, GABAB1 and GABAB2. Both subunits share structural homology with other class-III G-protein-coupled receptors. They contain two main domains, a heptahelical domain typical of all G-protein-coupled receptors and a large ECD (extracellular domain). It has not been demonstrated whether the association of these two subunits is always required for function. However, GABAB2 plays a major role in coupling with G-proteins, and GABAB1 has been shown to bind GABA. To date, only ligands interacting with GABAB1-ECD have been identified. In the present study, we explored the mechanism of action of CGP7930, a compound described as a positive allosteric regulator of the GABAB receptor. We have shown that it can weakly activate the wild-type GABAB receptor, but also the GABAB2 expressed alone, thus being the first described agonist of GABAB2. CGP7930 retains its weak agonist activity on a GABAB2 subunit deleted of its ECD. Thus the heptahelical domain of GABAB2 behaves similar to a rhodopsin-like receptor. These results open new strategies for studying the mechanism of activation of GABAB receptor and examine any possible role of GABAB2.
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Affiliation(s)
- V Binet
- Laboratory of Functional Genomics, CNRS UPR-2580, Montpellier, France
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Bettler B, Kaupmann K, Mosbacher J, Gassmann M. Molecular structure and physiological functions of GABA(B) receptors. Physiol Rev 2004; 84:835-67. [PMID: 15269338 DOI: 10.1152/physrev.00036.2003] [Citation(s) in RCA: 640] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
GABA(B) receptors are broadly expressed in the nervous system and have been implicated in a wide variety of neurological and psychiatric disorders. The cloning of the first GABA(B) receptor cDNAs in 1997 revived interest in these receptors and their potential as therapeutic targets. With the availability of molecular tools, rapid progress was made in our understanding of the GABA(B) system. This led to the surprising discovery that GABA(B) receptors need to assemble from distinct subunits to function and provided exciting new insights into the structure of G protein-coupled receptors (GPCRs) in general. As a consequence of this discovery, it is now widely accepted that GPCRs can exist as heterodimers. The cloning of GABA(B) receptors allowed some important questions in the field to be answered. It is now clear that molecular studies do not support the existence of pharmacologically distinct GABA(B) receptors, as predicted by work on native receptors. Advances were also made in clarifying the relationship between GABA(B) receptors and the receptors for gamma-hydroxybutyrate, an emerging drug of abuse. There are now the first indications linking GABA(B) receptor polymorphisms to epilepsy. Significantly, the cloning of GABA(B) receptors enabled identification of the first allosteric GABA(B) receptor compounds, which is expected to broaden the spectrum of therapeutic applications. Here we review current concepts on the molecular composition and function of GABA(B) receptors and discuss ongoing drug-discovery efforts.
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Affiliation(s)
- Bernhard Bettler
- Pharmazentrum, Dept. of Clinical-Biological Sciences, Institute of Physiology, Univ. of Basel, Klingelbergstr. 50, CH-4056 Basel, Switzerland.
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Diaz SL, Kemmling AK, Bonavita CD, Rubio MC, Balerio GN. Baclofen reestablishes ?-opioid receptor levels modified by morphine withdrawal syndrome in either sex. Synapse 2004; 54:24-9. [PMID: 15300881 DOI: 10.1002/syn.20061] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
We have previously shown that the GABA(B) agonist baclofen (BAC) prevents the expression of morphine (MOR) withdrawal syndrome in male as well as female mice. In addition, we have demonstrated that BAC reestablishes the dopamine levels modified by MOR withdrawal syndrome in male mice. The aim of the present study was to evaluate the micro-opioid receptor binding parameters in striatum and frontal cortex of male and female mice during MOR withdrawal and its prevention with BAC. Prepubertal Swiss-Webster mice of either sex were rendered dependent by intraperitoneal (i.p.) injection of MOR (2 mg/kg) twice daily for 9 days. On the tenth day, dependent animals received naloxone (NAL) (6 mg/kg, i.p.) 60 min after the last dose of MOR and another pool of dependent mice received BAC (2 mg/kg, i.p.) previous to NAL injection. Thirty min after NAL or saline injection mice were sacrificed, brains were collected, and the striatum and frontal cortex were dissected in order to perform binding studies with [(3)H][DAMGO]. The density of micro-opioid receptor increased significantly during MOR withdrawal in male and female striatum as well as in male cortex. In addition, in both brain areas the B(max) was higher in male than in female mice during MOR withdrawal. Finally, BAC pretreatment of MOR withdrawn mice reestablished the levels of micro-opioid receptor by significantly decreasing the B(max) in either sex. In conclusion, although there were sex differences in the micro-opioid receptor density during MOR withdrawal syndrome, BAC was able to reestablish the changes in binding parameters induced by the NAL-precipitated withdrawal in female and male mice.
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Affiliation(s)
- Silvina L Diaz
- Cátedra de Farmacología, Facultad de Farmacia y Bioquímica (Universidad de Buenos Aires); Instituto de Investigaciones Farmacológicas, Buenos Aires, Argentina
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Scattoni ML, Calamandrei G, Ricceri L. Neonatal cholinergic lesions and development of exploration upon administration of the GABAa receptor agonist muscimol in preweaning rats. Pharmacol Biochem Behav 2003; 76:213-21. [PMID: 14592672 DOI: 10.1016/s0091-3057(03)00191-6] [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: 11/22/2022]
Abstract
Neonatal rats were administered 192 IgG-saporin (192 IgG-Sap), a selective cholinergic immunotoxin, on postnatal day (PND) 7. Behavioural responsiveness to muscimol, a GABAa receptor agonist, was then assessed using locomotor activity and object exploration tests on PND 18. In Experiment 1, 192 IgG-Sap-lesioned and control rats were injected with the GABAa agonist, muscimol, on PND 18 and tested in a standard open field test. Muscimol reduced rearing responses in both control and 192 IgG-Sap-lesioned animals whereas reduced wall-rearing responses occurred in control animals only. 192 IgG-Sap also reduced rearing and wall-rearing responses. In Experiment 2, muscimol effects were evaluated on PND 18 in a spatial open field test in which object exploration in addition to locomotion and rearing responses was assessed. Neonatal cholinergic lesion per se increased locomotion during object exploration while decreasing time spent exploring objects. Depressant effects of muscimol on object exploration were also evident. As a whole, these data provide evidence for (i) basal forebrain (BF) cholinergic control on locomotor activity and object exploration and (ii) GABAa-mediated regulation of selective behavioural patterns associated with locomotion and exploration in weaning rats. Neonatal cholinergic lesions, however, do not appear to alter reactivity to GABAergic agonists in juvenile rats.
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Affiliation(s)
- M L Scattoni
- Section of Comparative Psychology, Laboratory of Pathophysiology, Istituto Superiore di Sanità, V le Regina Elena 299, Rome 00161, Italy
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