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Vasović D, Divović B, Treven M, Knutson DE, Steudle F, Scholze P, Obradović A, Fabjan J, Brković B, Sieghart W, Ernst M, Cook JM, Savić MM. Trigeminal neuropathic pain development and maintenance in rats are suppressed by a positive modulator of α6 GABA A receptors. Eur J Pain 2019; 23:973-984. [PMID: 30633839 PMCID: PMC6461498 DOI: 10.1002/ejp.1365] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 12/13/2018] [Accepted: 12/19/2018] [Indexed: 01/06/2023]
Abstract
γ-Aminobutyric acid type A (GABAA ) receptors containing the α6 subunit are located in trigeminal ganglia, and their reduction by small interfering RNA increases inflammatory temporomandibular and myofascial pain in rats. We thus hypothesized that enhancing their activity may help in neuropathic syndromes originating from the trigeminal system. Here, we performed a detailed electrophysiological and pharmacokinetic analysis of two recently developed deuterated structurally similar pyrazoloquinolinone compounds. DK-I-56-1 at concentrations below 1 µM enhanced γ-aminobutyric acid (GABA) currents at recombinant rat α6β3γ2, α6β3δ and α6β3 receptors, whereas it was inactive at most GABAA receptor subtypes containing other α subunits. DK-I-87-1 at concentrations below 1 µM was inactive at α6-containing receptors and only weakly modulated other GABAA receptors investigated. Both plasma and brain tissue kinetics of DK-I-56-1 were relatively slow, with half-lives of 6 and 13 hr, respectively, enabling the persistence of estimated free brain concentrations in the range 10-300 nM throughout a 24-hr period. Results obtained in two protocols of chronic constriction injury of the infraorbital nerve in rats dosed intraperitoneally with DK-I-56-1 during 14 days after surgery or with DK-I-56-1 or DK-I-87-1 during 14 days after trigeminal neuropathy were already established, demonstrated that DK-I-56-1 but not DK-I-87-1 significantly reduced the hypersensitivity response to von Frey filaments. SIGNIFICANCE: Neuropathic pain induced by trigeminal nerve damage is poorly controlled by current treatments. DK-I-56-1 that positively modulates α6 GABAA receptors is appropriate for repeated administration and thus may represent a novel treatment option against the development and maintenance of trigeminal neuropathic pain.
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Affiliation(s)
- Dina Vasović
- School of Dental Medicine, University of Belgrade, Belgrade, Serbia
| | - Branka Divović
- Faculty of Pharmacy, Department of Pharmacology, University of Belgrade, Belgrade, Serbia
| | - Marco Treven
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Daniel E Knutson
- Department of Chemistry and Biochemistry, Milwaukee Institute of Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Friederike Steudle
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Aleksandar Obradović
- Faculty of Pharmacy, Department of Pharmacology, University of Belgrade, Belgrade, Serbia
| | - Jure Fabjan
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Božidar Brković
- School of Dental Medicine, University of Belgrade, Belgrade, Serbia
| | - Werner Sieghart
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Margot Ernst
- Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - James M Cook
- Department of Chemistry and Biochemistry, Milwaukee Institute of Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin
| | - Miroslav M Savić
- Faculty of Pharmacy, Department of Pharmacology, University of Belgrade, Belgrade, Serbia
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