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Knutson DE, Kodali R, Divović B, Treven M, Stephen MR, Zahn NM, Dobričić V, Huber AT, Meirelles MA, Verma RS, Wimmer L, Witzigmann C, Arnold LA, Chiou LC, Ernst M, Mihovilovic MD, Savić MM, Sieghart W, Cook JM. Design and Synthesis of Novel Deuterated Ligands Functionally Selective for the γ-Aminobutyric Acid Type A Receptor (GABA AR) α6 Subtype with Improved Metabolic Stability and Enhanced Bioavailability. J Med Chem 2018; 61:2422-2446. [PMID: 29481759 DOI: 10.1021/acs.jmedchem.7b01664] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Recent reports indicate that α6β2/3γ2 GABAAR selective ligands may be important for the treatment of trigeminal activation-related pain and neuropsychiatric disorders with sensori-motor gating deficits. Based on 3 functionally α6β2/3γ2 GABAAR selective pyrazoloquinolinones, 42 novel analogs were synthesized, and their in vitro metabolic stability and cytotoxicity as well as their in vivo pharmacokinetics, basic behavioral pharmacology, and effects on locomotion were investigated. Incorporation of deuterium into the methoxy substituents of the ligands increased their duration of action via improved metabolic stability and bioavailability, while their selectivity for the GABAAR α6 subtype was retained. 8b was identified as the lead compound with a substantially improved pharmacokinetic profile. The ligands allosterically modulated diazepam insensitive α6β2/3γ2 GABAARs and were functionally silent at diazepam sensitive α1β2/3γ2 GABAARs, thus no sedation was detected. In addition, these analogs were not cytotoxic, which render them interesting candidates for treatment of CNS disorders mediated by GABAAR α6β2/3γ2 subtypes.
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Affiliation(s)
- Daniel E Knutson
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery , University of Wisconsin-Milwaukee , 3210 N. Cramer St. , Milwaukee , Wisconsin 53211 , United States
| | - Revathi Kodali
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery , University of Wisconsin-Milwaukee , 3210 N. Cramer St. , Milwaukee , Wisconsin 53211 , United States
| | - Branka Divović
- Department of Pharmacology, Faculty of Pharmacy , University of Belgrade , Vojvode Stepe 450 , 11221 Belgrade , Serbia
| | - Marco Treven
- Department of Molecular Neurosciences, Center for Brain Research , Medical University of Vienna , Spitalgasse 4 , A-1090 Vienna , Austria
| | - Michael R Stephen
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery , University of Wisconsin-Milwaukee , 3210 N. Cramer St. , Milwaukee , Wisconsin 53211 , United States
| | - Nicolas M Zahn
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery , University of Wisconsin-Milwaukee , 3210 N. Cramer St. , Milwaukee , Wisconsin 53211 , United States
| | - Vladimir Dobričić
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy , University of Belgrade , Vojvode Stepe 450 , 11221 Belgrade , Serbia
| | - Alec T Huber
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery , University of Wisconsin-Milwaukee , 3210 N. Cramer St. , Milwaukee , Wisconsin 53211 , United States
| | - Matheus A Meirelles
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery , University of Wisconsin-Milwaukee , 3210 N. Cramer St. , Milwaukee , Wisconsin 53211 , United States
| | - Ranjit S Verma
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery , University of Wisconsin-Milwaukee , 3210 N. Cramer St. , Milwaukee , Wisconsin 53211 , United States
| | - Laurin Wimmer
- TU Wien-Institute of Applied Synthetic Chemistry , Getreidemarkt 9/163 , A-1060 Vienna , Austria
| | - Christopher Witzigmann
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery , University of Wisconsin-Milwaukee , 3210 N. Cramer St. , Milwaukee , Wisconsin 53211 , United States
| | - Leggy A Arnold
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery , University of Wisconsin-Milwaukee , 3210 N. Cramer St. , Milwaukee , Wisconsin 53211 , United States
| | - Lih-Chu Chiou
- Graduate Institute of Acupuncture Science , China Medical University , Taichung 40402 , Taiwan
| | - Margot Ernst
- Department of Molecular Neurosciences, Center for Brain Research , Medical University of Vienna , Spitalgasse 4 , A-1090 Vienna , Austria
| | - Marko D Mihovilovic
- TU Wien-Institute of Applied Synthetic Chemistry , Getreidemarkt 9/163 , A-1060 Vienna , Austria
| | - Miroslav M Savić
- Department of Pharmacology, Faculty of Pharmacy , University of Belgrade , Vojvode Stepe 450 , 11221 Belgrade , Serbia
| | - Werner Sieghart
- Department of Molecular Neurosciences, Center for Brain Research , Medical University of Vienna , Spitalgasse 4 , A-1090 Vienna , Austria
| | - James M Cook
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery , University of Wisconsin-Milwaukee , 3210 N. Cramer St. , Milwaukee , Wisconsin 53211 , United States
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June HL, Devaraju SL, Eggers MW, Williams JA, Cason CR, Greene TL, Leveige T, Braun MR, Torres L, Murphy JM. Benzodiazepine receptor antagonists modulate the actions of ethanol in alcohol-preferring and -nonpreferring rats. Eur J Pharmacol 1998; 342:139-51. [PMID: 9548379 DOI: 10.1016/s0014-2999(97)01489-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The pyrazoloquinoline CGS 8216 (2-phenylpyrazolo-[4,3-c]-quinolin-3 (5H)-one, 0.05-2 mg/kg) and the beta-carboline ZK 93426 (ethyl-5-isopropyl-4-methyl-beta-carboline-3-carboxylate, 1-10 mg/kg) benzodiazepine receptor antagonists were evaluated for their capacity to modulate the behavioral actions of ethanol in alcohol preferring and -nonpreferring rats. When alcohol-preferring rats were presented with a two-bottle choice test between ethanol (10% v/v) and a saccharin (0.0125% g/v) solution, both antagonists dose-dependently reduced intake of ethanol by 35-92% of control levels on day 1 at the initial 15 min interval of the 4 h limited access. Saccharin drinking was suppressed only with the highest doses. CGS 8216 (0.25 mg/kg) and ZK 93426 (4 mg/kg) unmasked the anxiolytic effects of a hypnotic ethanol dose (1.5 g/kg ethanol) on the plus maze test in alcohol-preferring rats, but potentiated the ethanol-induced suppression in alcohol-nonpreferring rats. CGS 8216 (0.25 mg/kg) and ZK 93426 (4 mg/kg) attenuated the ethanol (0.5 and 1.5 g/kg)-induced suppression in the open field in alcohol-nonpreferring rats; however, CGS 8216 potentiated the depressant effects of the lower ethanol dose (0.5 g/kg) in alcohol-preferring rats. These findings provide evidence that benzodiazepine receptor antagonists may differentially modulate the behavioral actions of ethanol in alcohol-preferring and-nonpreferring rats. It is possible that the qualitative pharmacodynamic differences seen in the present study may be related to selective breeding for alcohol preference. The findings indicate the potential for development of receptor specific ligands devoid of toxic effects which may be useful in the treatment of alcohol abuse and alcoholism.
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Affiliation(s)
- H L June
- Department of Psychology, Indiana University School of Medicine, Indiana University-Purdue University, Indianapolis 46202-3275, USA.
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Gardner CR, Budhram P, Parker FL. Discriminative stimulus properties of RU 33965, a benzodiazepine receptor weak partial inverse agonist. Pharmacol Biochem Behav 1992; 43:583-8. [PMID: 1359581 DOI: 10.1016/0091-3057(92)90194-k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rats were trained to discriminate the low-efficacy benzodiazepine receptor inverse agonist RU 33965 from vehicle in a two-lever discrimination task on a fixed ratio (FR) 20 schedule. Consistent discrimination was obtained at 0.5 mg/kg PO RU 33965. Both leptazol and stronger inverse agonists (FG7142, S-135, RU 34000) substituted for the cue. The weak inverse agonists/antagonists RU 33094, RU 34030, Ro 15-1788, and ZK 93426 also substituted for the cue with the latter two compounds being particularly potent. The agonist and partial agonists diazepam, RU 33203, and RU 39419 did not substitute for the RU 33965 cue but RU 39419 antagonised it. The full agonists diazepam and loprazolam only consistently antagonised the cue when given IP 5 min pretest. These data suggest that the RU 33965 cue results from its weak inverse agonist activity at benzodiazepine receptors, but kinetic factors must be considered when interpreting drug effects in discrimination studies.
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Affiliation(s)
- C R Gardner
- Roussel Laboratories Limited, Swindon, Wiltshire, UK
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Kumar BA, Forster MJ, Lal H. CGS 8216, a benzodiazepine receptor antagonist, enhances learning and memory in mice. Brain Res 1988; 460:195-8. [PMID: 3219570 DOI: 10.1016/0006-8993(88)91223-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Mice pretreated with the benzodiazepine antagonist, CGS 8216 (2.5, 10, or 40 mg/kg, i.p.) learned a T-maze discrimination to a fixed performance criterion more rapidly than vehicle-treated mice. In retention tests conducted one week later, the drug-treated groups had better first-trial recall and greater difficulty reversing the previously trained maze habit when compared with controls, suggesting improved memory for the previously trained maze habit. The enhanced acquisition and retention following CGS 8216 was similar to that observed previously with another benzodiazepine antagonist, flumazenil (Ro 15-1788). It is postulated that CGS 8216 and flumazenil could act at benzodiazepine receptors to antagonize a tonic inhibitory influence of endogenous, diazepam-like, benzodiazepine receptor ligands on memory processes.
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Affiliation(s)
- B A Kumar
- Department of Pharmacology, Texas College of Osteopathic Medicine, Fort Worth 76107-2690
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Rodgers RJ, Randall JI. Are the analgesic effects of social defeat mediated by benzodiazepine receptors? Physiol Behav 1987; 41:279-89. [PMID: 2829247 DOI: 10.1016/0031-9384(87)90364-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Social conflict in mice is associated with at least two forms of analgesia. A long-lasting opioid reaction is evident in intruder mice exposed to prolonged attack, whilst an acute non-opioid analgesia is seen in response to either defeat experience per se or the territorial scent-marking of an aggressive conspecific. Recent work from this laboratory has suggested that the non-opioid analgesic reaction to defeat experience may be mediated via benzodiazepine receptor mechanisms. The present studies were designed to further test this tentative hypothesis. Results confirmed that defeat analgesia is dose-dependently blocked by Ro15-1788 (20-40 mg/kg) and diazepam (2-4 mg/kg), and also indicated partial antagonism of the reaction by CGS8216 (2.5 mg/kg). The partial agonists CGS9896 (2.5-20 mg/kg) and ZK91296 (2.5-20 mg/kg) were ineffective in blocking the reaction, a finding also obtained with the full agonist ZK93423 (0.05-10 mg/kg). However, the antagonist/weak inverse agonist ZK93426 was found to possess significant intrinsic analgesic activity (10 mg/kg) and to enhance defeat analgesia (5-10 mg/kg). Although several interpretative frameworks for the current pharmacological profile are considered, it is concluded that full clarification of the substrates of defeat analgesia must await further investigations.
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Affiliation(s)
- R J Rodgers
- Pharmacoethology Laboratory, School of Psychology, University of Bradford, U.K
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Rodgers RJ, Randall JI. Benzodiazepine ligands, nociception and 'defeat' analgesia in male mice. Psychopharmacology (Berl) 1987; 91:305-15. [PMID: 3104952 DOI: 10.1007/bf00518182] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Recent studies have indicated that defeat experience induces acute non-opioid analgesia in intruder mice. To investigate the potential involvement of benzodiazepine receptors in this biologically-relevant form of environmentally-induced antinociception, we initially assessed the effects of some benzodiazepine ligands on basal nociception (tail-flick assay). Chlordiazepoxide (5-30 mg/kg), midazolam (0.625-5 mg/kg), diazepam (0.5-4 mg/kg), Ro15-1788 (5-80 mg/kg) and CGS8216 (5 mg/kg) were found to be ineffective in altering basal nociception. However, higher doses of CGS8216 (10-20 mg/kg) induced significant analgesia, an effect also observed with the beta-carboline derivatives FG7142 (5-20 mg/kg) and DMCM (1-2 mg/kg). Time-course analyses revealed that the onset of CGS8216 analgesia was slower than for FG7142 and DMCM, but that all three drugs produced long-lasting elevations in tail-flick latencies. The analgesic effects of FG7142 and DMCM were completely reversed by Ro15-1788 (20 mg/kg) and by chlordiazepoxide (20 mg/kg), suggesting mediation by benzodiazepine receptor mechanisms. Although CGS8216 analgesia was also reversed by Ro15-1788, it was unaffected by chlordiazepoxide; however, diazepam (5 mg/kg) did significantly attenuate the reaction. Further studies indicated that the antinociceptive consequences of defeat experience were dose-dependently blocked by Ro15-1788 (10-40 mg/kg) and by diazepam (0.5-2 mg/kg). Surprisingly, however, neither chlordiazepoxide (5-20 mg/kg) nor midazolam (1.25-2.5 mg/kg) blocked "defeat" analgesia under present test conditions. Although several issues remain unresolved, present findings would not be inconsistent with the proposal that stimuli associated with the acute stress of defeat experience release an endogenous ligand which acts in an "inverse agonist-like" manner at benzodiazepine sites.
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