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McNaughton N, Swart C, Neo P, Bates V, Glue P. Anti-anxiety drugs reduce conflict-specific "theta"--a possible human anxiety-specific biomarker. J Affect Disord 2013; 148:104-11. [PMID: 23261140 DOI: 10.1016/j.jad.2012.11.057] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 11/22/2012] [Accepted: 11/24/2012] [Indexed: 11/25/2022]
Abstract
BACKGROUND Syndromes of fear/anxiety are currently ill-defined, with no accepted human biomarkers for anxiety-specific processes. A unique common neural action of different classes of anxiolytic drugs may provide such a biomarker. In rodents, a reduction in low frequency (4-12 Hz; "theta") brain rhythmicity is produced by all anxiolytics (even those lacking panicolytic or antidepressant action) and not by any non-anxiolytics. This rhythmicity is a key property of the Behavioural Inhibition System (BIS) postulated to be one neural substrate of anxiety. We sought homologous anxiolytic-sensitive changes in human surface EEG rhythmicity. METHOD Thirty-four healthy volunteers in parallel groups were administered double blind single doses of triazolam 0.25mg, buspirone 10mg or placebo 1 hour prior to completing the stop-signal task. Right frontal conflict-specific EEG power (previously shown to correlate with trait anxiety and neuroticism in this task) was extracted as a contrast between trials with balanced approach-avoidance (stop-go) conflict and the average of trials with net approach and net avoidance. RESULTS Compared with placebo, both triazolam and buspirone decreased right-frontal, 9-10 Hz, conflict-specific-power. LIMITATIONS Only one dose of each of only two classes of anxiolytic and no non-anxiolytics were tested, so additional tests are needed to determine generality. CONCLUSIONS There is a distinct rhythmic system in humans that is sensitive to both classical/GABAergic and novel/serotonergic anxiolytics. This conflict-specific rhythmicity should provide a biomarker, with a strong pre-clinical neuropsychology, for a novel approach to classifying anxiety disorders.
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Affiliation(s)
- Neil McNaughton
- Department of Psychology and Department of Psychological Medicine, University of Otago, POB56, Dunedin 9054, New Zealand.
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2
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Baastrup C, Jensen TS, Finnerup NB. Coexisting mechanical hypersensitivity and anxiety in a rat model of spinal cord injury and the effect of pregabalin, morphine, and midazolam treatment. Scand J Pain 2011; 2:139-145. [DOI: 10.1016/j.sjpain.2011.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 02/16/2011] [Indexed: 10/18/2022]
Abstract
Abstract
Background and purpose
Spinal cord injury (SCI) has detrimental consequences that include chronic neuropathic pain, which is seen in 40-50% of patients, and symptoms of anxiety and depression, which affect 13-45% of SCI patients. The coexistence of pain, anxiety, and depression is known from other neuropathic pain conditions, but the relationship between these symptoms is not clear and has not been investigated in a preclinical model of SCI so far.
The aim of this study was to investigate anxiety-like behavior and at-level mechanical hypersensitivity following experimental spinal cord contusion (SCC) in female Sprague-Dawley rats, and the effects of analgesic and anxiolytic drugs.
Methods
Mechanical sensitivity and elevated plus maze (EPM) behavior were measured pre- and postinjury in SCC and sham animals. Pregabalin 30 mg/kg, morphine 3 mg/kg, midazolam 0.5 mg/kg, and 0.9% NaCl were evaluated in a randomly allocated, blinded balanced design.
Results
SCC animals developed persistent at-level mechanical hypersensitivity and decreased open arm activity in the EPM, which indicates an anxiety-like state. Pregabalin, a dual-acting analgesic and anxiolytic drug reduced both hypersensitivity and anxiety-like behavior, while the analgesic drug morphine only reduced hypersensitivity. The anxiolytic drug midazolam in the dose used had no effect on either parameter.
Conclusions
SCC animals developed long lasting coexisting at-level mechanical hypersensitivity and anxiety-like behavior, but there was no evidence to support a causal relationship between pain and anxiety following SCI.
Implications
The findings that at-level mechanical hypersensitivity and anxiety-like behavior develops concomitantly in the spinal cord contusion models and that both symptoms is persistent provide basis for further investigation of the mechanisms and connection behind these two clinically relevant symptoms after injury to the central nervous system.
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Affiliation(s)
- Cathrine Baastrup
- Danish Pain Research Center , Aarhus University Hospital , Norrebrogade 44, Building 1A, DK-8000 Aarhus C , Aarhus , Denmark
| | - Troels S. Jensen
- Danish Pain Research Center , Aarhus University Hospital , Norrebrogade 44, Building 1A, DK-8000 Aarhus C , Aarhus , Denmark
- Department of Neurology , Aarhus University Hospital , Norrebrogade 44, DK-8000 Aarhus C , Aarhus , Denmark
| | - Nanna B. Finnerup
- Danish Pain Research Center , Aarhus University Hospital , Norrebrogade 44, Building 1A, DK-8000 Aarhus C , Aarhus , Denmark
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Bouton ME, Westbrook RF, Corcoran KA, Maren S. Contextual and temporal modulation of extinction: behavioral and biological mechanisms. Biol Psychiatry 2006; 60:352-60. [PMID: 16616731 DOI: 10.1016/j.biopsych.2005.12.015] [Citation(s) in RCA: 493] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Revised: 11/23/2005] [Accepted: 12/22/2005] [Indexed: 10/24/2022]
Abstract
Extinction depends, at least partly, on new learning that is specific to the context in which it is learned. Several behavioral phenomena (renewal, reinstatement, spontaneous recovery, and rapid reacquisition) suggest the importance of context in extinction. The present article reviews research on the behavioral and neurobiological mechanisms of contextual influences on extinction learning and retrieval. Contexts appear to select or retrieve the current relationship of the conditional stimulus (CS) with the unconditional stimulus (US), and they are provided by physical background cues, interoceptive drug cues, emotions, recent trials, and the passage of time. The current article pays particular attention to the effects of recent trials and trial spacing. Control of fear extinction by physical context involves interactions between the dorsal hippocampus and the lateral nucleus of the amygdala. This interaction may be mediated by gamma-aminobutyric acid (GABA)-ergic and adrenergic mechanisms.
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Affiliation(s)
- Mark E Bouton
- Department of Psychology, University of Vermont, Burlington, Vermont 05405-0134, USA.
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5
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Pan WX, McNaughton N. The supramammillary area: its organization, functions and relationship to the hippocampus. Prog Neurobiol 2004; 74:127-66. [PMID: 15556285 DOI: 10.1016/j.pneurobio.2004.09.003] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2004] [Accepted: 09/15/2004] [Indexed: 11/18/2022]
Abstract
The supramammillary area of the hypothalamus, although small in size, can have profound modulatory effects on the hippocampal formation and related temporal cortex. It can control hippocampal plasticity and also has recently been shown to contain cells that determine the frequency of hippocampal rhythmical slow activity (theta rhythm). We review here its organization and anatomical connections providing an atlas and a new nomenclature. We then review its functions particularly in relation to its links with the hippocampus. Much of its control of behaviour and its differential activation by specific classes of stimuli is consistent with a tight relationship with the hippocampus. However, its ascending connections involve not only caudal areas of the cortex with close links to the hippocampus but also reciprocal connections with more rostral areas such as the infralimbic and anterior cingulate cortices. These latter areas appear to be the most rostral part of a network that, via the medial septum, hippocampus and lateral septum, is topographically mapped into the hypothalamus. The supramammillary area is thus diffusely connected with areas that control emotion and cognition and receives more topographically specific return information from areas that control cognition while also receiving ascending information from brain stem areas involved in emotion. We suggest that it is a key part of a network that recursively transforms information to achieve integration of cognitive and emotional aspects of goal-directed behaviour.
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Affiliation(s)
- Wei-Xing Pan
- Department of Physiology and Center for Neuroscience, University of Otago, POB56, Dunedin, New Zealand
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7
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Abstract
1. Studies on the pathogenesis of panic disorder (PD) have concentrated on panic attacks. However, PD runs a chronic or episodic course and panic patients remain clinically unwell between attacks. Panic patients chronically hyperventilate, but the implications of this are unclear. 2. Provocation of panic experimentally has indicated that several biological mechanisms may be involved in the onset of panic symptoms. Evidence from provocation studies using lactate, but particularly carbon dioxide (CO2) mixtures, suggests that panic patients may have hypersensitive CO2 chemoreceptors. Klein proposed that PD may be due to a dysfunctional brain's suffocation alarm and that panic patients hyperventilate to keep pCO2 low. 3. Studies of panic patients in the non-panic state have shown EEG abnormalities in this patient group, as well as abnormalities in cerebral blood flow and cerebral glucose metabolism. These abnormalities can be interpreted as signs of cerebral hypoxia that may have resulted from hyperventilation. 4. Cerebral hypoxia is probably involved in the causation of symptoms of anxiety in sufferers of chronic obstructive pulmonary diseases. By chronically hyperventilating, panic patients may likewise be at risk of exposure to prolonged periods of cerebral hypoxia which, in turn, may contribute to the chronicity of their panic and anxiety symptoms. 5. Chronic hyperventilation may engender a self-perpetuating mechanism within the pathophysiology of PD, a hypothesis which warrants further studies of panic patients in the non-panic state.
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Affiliation(s)
- L Dratcu
- Guy's Hospital, Division of Psychiatry, Guy's, King's and St Thomas' School of Medical Sciences, London, United Kingdom
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8
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Morrow BA, Elsworth JD, Lee EJ, Roth RH. Divergent effects of putative anxiolytics on stress-induced fos expression in the mesoprefrontal system of the rat. Synapse 2000; 36:143-54. [PMID: 10767061 DOI: 10.1002/(sici)1098-2396(200005)36:2<143::aid-syn7>3.0.co;2-h] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Previously, we reported that R(+)HA-966, a weak partial agonist for the glycine/NMDA receptor, and guanfacine, a noradrenergic alpha2 agonist, have anxiolytic-like actions on the biochemical activation of the mesoprefrontal dopamine neurons and fear-induced behaviors. Here, we examined these two putative anxiolytic agents, both with primary actions independent of GABAergic systems, for their ability to alter stress-induced Fos-like immunoreactivity in the mesoprefrontal cortex and in tyrosine hydroxylase-stained, presumed dopaminergic, neurons in the ventral tegmental area. The benzodiazepine agonist, lorazepam, and partial agonist, bretazenil, were also tested in this footshock paradigm [10 x 0.5 sec, 0.8 mA paired with a 5-sec tone]. In saline-treated rats, footshock resulted in an increase in Fos-li in the prelimbic and infralimbic cortices and tyrosine hydroxylase-labeled cells in the ventral tegmental area. Treatment with lorazepam or bretazenil prevented the stress-induced activation in Fos-li nuclei in all regions of the medial prefrontal cortex and in dopaminergic neurons in the ventral tegmental area. In contrast, the actions of the novel anxiolytic-like agents on stress-induced Fos-li were different than those observed with benzodiazepine agonists. Both putative anxiolytics, R(+)HA-966 and guanfacine, did not reduce, but significantly enhanced the stress-induced Fos-li in the prelimbic region of the medial prefrontal cortex. Additionally, treatment with R(+)HA-966 completely blocked, while guanfacine attenuated, the stress-induced increase in the number of Fos-li, TH-li cells in the ventral tegmental area. These results indicate that the putative anxiolytics, R(+)HA-966 and guanfacine, have actions on the stress-sensitive mesoprefrontal system which appear distinct from those of traditional anxiolytics.
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Affiliation(s)
- B A Morrow
- Department of Pharmacology, Laboratory of Neuropsychopharmacology, Yale University School of Medicine, New Haven, Connecticut 06520-8066, USA.
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Jacobsen EJ, Stelzer LS, TenBrink RE, Belonga KL, Carter DB, Im HK, Im WB, Sethy VH, Tang AH, VonVoigtlander PF, Petke JD, Zhong WZ, Mickelson JW. Piperazine imidazo[1,5-a]quinoxaline ureas as high-affinity GABAA ligands of dual functionality. J Med Chem 1999; 42:1123-44. [PMID: 10197957 DOI: 10.1021/jm9801307] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of imidazo[1,5-a]quinoxaline piperazine ureas appended with a tert-butyl ester side chain at the 3-position was developed. Analogues within this series have high affinity for the gamma-aminobutyric acid A (GABAA)/benzodiazepine receptor complex with efficacies ranging from inverse agonists to full agonists. Many analogues were found to be partial agonists as indicated by [35S]TBPS and Cl- current ratios. Uniquely, a number of these analogues were found to have a bell-shaped dose-response profile in the alpha1 beta2 gamma2 subtype as determined by whole cell patch-clamp technique, where in vitro efficacy was found to decrease with increasing drug concentration. Many of the compounds from this series were effective in antagonizing metrazole-induced seizures, consistent with anticonvulsant and possibly anxiolytic activity. Additionally, several analogues were also effective in lowering cGMP levels (to control values) after applied stress, also consistent with anxiolytic-like properties. The most effective compounds in these screens were also active in animal models of anxiety such as the Vogel and Geller assays. The use of the piperazine substituent allowed for excellent drug levels and a long duration of action in the central nervous system for many of the quinoxalines, as determined by ex vivo assay. Pharmacokinetic analysis of several compounds indicated excellent oral bioavailability and a reasonable half-life in rats. From this series emerged two partial agonists (55, 91) which had good activity in anxiolytic models, acceptable pharmacokinetics, and minimal benzodiazepine-type side effects.
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Affiliation(s)
- E J Jacobsen
- Departments of Structural, Analytical and Medicinal Chemistry, Central Nervous System Diseases Research, Computer Aided Drug Discovery, and Pharmacokinetics and Bioanalysis Research, Upjohn Laboratories, Kalamazoo, Michigan 49001, USA
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Da Settimo A, Primofiore G, Da Settimo F, Marini AM, Novellino E, Greco G, Gesi M, Martini C, Giannaccini G, Lucacchini A. N'-Phenylindol-3-ylglyoxylohydrazide derivatives: synthesis, structure-activity relationships, molecular modeling studies, and pharmacological action on brain benzodiazepine receptors. J Med Chem 1998; 41:3821-30. [PMID: 9748357 DOI: 10.1021/jm9800301] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A series of N'-phenylindol-3-ylglyoxylohydrazides, isosters of the N-benzylindol-3-ylglyoxylamide derivatives previously described by us, were synthesized and tested for their ability to displace [3H]Ro 15-1788 from bovine brain membranes. These compounds were designed with the aim of obtaining products which could exert an in vivo activity, thanks to a higher hydrosolubility and consequently a better bioavailability. Affinity was restricted to the derivatives unsubstituted in the 5 position of the indole nucleus (1, 6, 9, 12, 15, 18, 23, and 26), with Ki values ranging from 510 to 11 nM. The most active compounds (6, 9, 23, and 29) proved to be effective in antagonizing pentylenetetrazole-induced seizures. Molecular modeling studies were performed to rationalize the lack of affinity of hydrazides with a chloro or a nitro group in the 5 position of the indole nucleus. It was hypothesized that the conformational preference of the hydrazide side chain, characterized by a gauche disposition of lone pairs and substituents about the N-N bond, prevents all hydrazides from binding to the receptor similarly to other classes of indole analogues previously investigated. The potency of 5-H hydrazides was attributed to a binding mode which is not feasible for 5-Cl and 5-NO2 counterparts. This theoretical model of ligand-receptor interaction permitted a more stringent interpretation of structure-affinity relationships of hydrazides and of recently described benzylamide derivatives (Da Settimo et al. J. Med. Chem. 1996, 39, 5083-5091).
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Affiliation(s)
- A Da Settimo
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, Via Bonanno 6, 56126 Pisa, Italy
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11
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Dunn RW, Reed TA, Copeland PD, Frye CA. The nitric oxide synthase inhibitor 7-nitroindazole displays enhanced anxiolytic efficacy without tolerance in rats following subchronic administration. Neuropharmacology 1998; 37:899-904. [PMID: 9776385 DOI: 10.1016/s0028-3908(98)00076-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The nitric oxide synthase inhibitor 7-nitroindazole (7-NI) dose-dependently (3.0-30.0 mg/kg) displayed anxiolytic activity, as measured by an increase in open arm exploration time in the elevated plus-maze (EPM), following intraperitoneal (i.p.) administration in rats. Acute administration of 7-NI at 30.0 mg/kg significantly (P < 0.05) increased open arm exploration time by 176% compared to vehicle control, similar to the benzodiazepine diazepam at 1.0 and 3.0 mg/kg (+ 191 and + 200%, respectively). However, 39 h following subchronic 5-day administration of diazepam twice daily (bid) at 3.0 mg/kg, diazepam was devoid of anxiolytic activity at 1.0 mg/kg, as measured by no difference in open arm exploration time compared to vehicle control, while the 3.0 mg/kg dose still produced a significant (P < 0.05) 175% increase in open arm exploration time. In contrast, following subchronic administration of 7-NI (30.0 mg/kg, bid), a significant (P < 0.01) enhancement in open arm exploration time was observed at 30.0 mg/kg (+ 665% compared to control). Therefore, inhibition of nitric oxide synthase by 7-NI resulted in anxiolysis similar to diazepam following acute administration in the EPM. However, following subchronic administration, unlike diazepam which showed an attenuation of anxiolytic activity, 7-NI displayed enhanced anxiolytic efficacy and was devoid of tolerance.
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Affiliation(s)
- R W Dunn
- NOS/CETS, Old Lyme, CT 06371, USA
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12
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Matto V, Harro J, Allikmets L. The effects of cholecystokinin A and B receptor antagonists on exploratory behaviour in the elevated zero-maze in rat. Neuropharmacology 1997; 36:389-96. [PMID: 9175618 DOI: 10.1016/s0028-3908(97)00011-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The aim of the present study was to investigate the effects of cholecystokinin (CCK) CCK(A) and CCKB receptor antagonists SR 27897 B, devazepide, L 365260 and PD 135158 (CAM 1028) on exploratory behaviour in the elevated zero-maze in the rat. For further validation of the elevated zero-maze, the effects of a reference anxiolytic diazepam (0.25, 0.5, 1.0, 2.0 mg/kg), a non-benzodiazepine (BDZ) anxiolytic buspirone (0.04, 0.2, 1.0, 5.0 mg/kg), BDZ receptor inverse agonists FG 7142 (5, 10, 15, 20 mg/kg) and DMCM (0.1, 0.5, 1.0, 1.5 mg/kg), and a BDZ receptor antagonist flumazenil (10 mg/kg) were studied. Diazepam decreased the number of stretched-attend postures in all doses used and increased the percentage of time spent exploring in open parts at doses of 0.5 and 1.0 mg/kg. The effects of diazepam were blocked by flumazenil. FG 7142 and DMCM had effects only in subconvulsive doses (20 mg/kg and 1.5 mg/kg). Flumazenil and buspirone failed to show any effect. The CCK(A) receptor antagonists were also without any effect. The CCK(B) receptor antagonists L 365260 (1.0 and 5.0 mg/kg) and PD 135158 (100 microg/kg) had a significant anxiolytic-like effect. The CCK(B) receptor antagonists increased the number of open part entries, the number of head dips, the percentage of time spent exploring in the open part and decreased the number of stretched-attend postures. These data support the hypothesis of the involvement of the CCK(B) receptor subtype in the neurobiological mechanisms of anxiety.
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Affiliation(s)
- V Matto
- Department of Pharmacology, University of Tartu, Estonia.
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Mickelson JW, Jacobsen EJ, Carter DB, Im HK, Im WB, Schreur PJ, Sethy VH, Tang AH, McGee JE, Petke JD. High-affinity alpha-aminobutyric acid A/benzodiazepine ligands: synthesis and structure-activity relationship studies of a new series of tetracyclic imidazoquinoxalines. J Med Chem 1996; 39:4654-66. [PMID: 8917654 DOI: 10.1021/jm960401i] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A series of tetracyclic imidazoquinoxaline analogs was developed which constrain the carbonyl group of the partial agonist 3-(5-cyclopropyl-1,2,4-oxadiazol-3-yl)-5-[(dimethylamino)carbonyl] - 4,5-dihydroimidazo[1,5-alpha]quinoxaline (2, U-91571) away from the benzene ring. These analogs orient the carbonyl group in the opposite direction of the previously reported full agonist 1-(5- cyclopropyl-1,2,4-oxadiazol-3-yl)-12,12a-dihydroimidazo[1,5- alpha]pyrrolo [2,1-c]quinoxalin-10(11H)-one (3, U-89267). A number of approaches were utilized to form the "bottom" ring of this tetracyclic ring system including intramolecular cyclizations promoted by Lewis acids or base, as well as metal-carbenoid conditions. The size and substitution pattern of the additional ring was widely varied. Analogs within this series had high affinity for the benzodiazepine receptor on the alpha-aminobutyric acid A chloride ion channel complex. From TBPS shift and Cl- current assays, the in vitro efficacy of compounds within this class ranged from antagonists to partial agonists with only 18a identified as a full agonist. Additionally, several analogs were quite potent at antagonizing metrazole-induced seizures indicating possible anticonvulsant or anxiolytic activity. Unlike 3, analogs in this series did not have high affinity for the diazepam insensitive alpha 6 beta 2 delta 2 subtype. These results suggest that either constraining the carbonyl group away from the benzene ring or the greater planarity that results from the additional cyclic structure provides analogs with partial agonist properties and prevents effective interaction with the alpha 6 beta 2 delta 2 subtype.
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Affiliation(s)
- J W Mickelson
- Department of Structural and Medicinal Chemistry, Upjohn Laboratories, Upjohn Company, Kalamazoo, Michigan 49001, USA
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14
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Jacobsen EJ, Stelzer LS, Belonga KL, Carter DB, Im WB, Sethy VH, Tang AH, VonVoigtlander PF, Petke JD. 3-Phenyl-substituted imidazo[1,5-alpha]quinoxalin-4-ones and imidazo[1,5-alpha]quinoxaline ureas that have high affinity at the GABAA/benzodiazepine receptor complex. J Med Chem 1996; 39:3820-36. [PMID: 8809170 DOI: 10.1021/jm960070+] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A series of imidazo[1,5-alpha]quinoxalin-4-ones and imidazo[1,5-alpha]quinoxaline ureas containing substituted phenyl groups at the 3-position was developed. Compounds within the imidazo[1,5-alpha]quinoxaline urea series had high affinity for the GABAA/benzodiazepine receptor complex with varying in vitro efficacy, although most analogs were partial agonists as indicated by [35S]TBPS and Cl- current ratios. Interestingly, a subseries of piperazine ureas was identified which had biphasic efficacy, becoming more antagonistic with increasing concentration. Analogs within the imidazo[1,5-alpha]quinoxalin-4-one series had substantially decreased binding affinity as compared to the quinoxaline urea series. These compounds ranged from antagonists to full agonists by in vitro analysis, with several derivatives having roughly 4-fold greater intrinsic activity than diazepam as indicated by Cl- current measurement. Numerous compounds from both series were effective in antagonizing metrazole-induced seizures, consistent with anti-convulsant properties and possible anxiolytic activity. Most of the quinoxaline ureas and quinoxalin-4-ones were active in an acute electroshock physical dependence side effect assay in mice precluding further development.
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Affiliation(s)
- E J Jacobsen
- Department of Structural Chemistry, Pharmacia & Upjohn, Kalamazoo, Michigan 49001, USA
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15
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Jacobsen EJ, TenBrink RE, Stelzer LS, Belonga KL, Carter DB, Im HK, Im WB, Sethy VH, Tang AH, VonVoigtlander PF, Petke JD. High-affinity partial agonist imidazo[1,5-a]quinoxaline amides, carbamates, and ureas at the gamma-aminobutyric acid A/benzodiazepine receptor complex. J Med Chem 1996; 39:158-75. [PMID: 8568803 DOI: 10.1021/jm940765f] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A series of imidazo[1,5-a]quinoxaline amides, carbamates, and ureas which have high affinity for the gamma-aminobutyric acid A/benzodiazepine receptor complex was developed. Compounds within this class have varying efficacies ranging from antagonists to full agonists. However, most analogs were found to be partial agonists as indicated by [35S]TBPS and Cl- current ratios. Many of these compounds were also effective in antagonizing metrazole-induced seizures in accordance with anticonvulsant and possible anxiolytic activity. Selected quinoxalines displayed limited benzodiazepine-type side effects such as ethanol potentiation and physical dependence in animal models. Dimethylamino urea 41 emerged as the most interesting analog, having a partial agonist profile in vitro while possessing useful activity in animal models of anxiety such as the Vogel and Geller assays. In accordance with its partial agonist profile, 41 was devoid of typical benzodiazepine side effects.
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Affiliation(s)
- E J Jacobsen
- Department of Medicinal Chemistry, Upjohn Laboratories, Upjohn Company, Kalamazoo, Michigan 49001, USA
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16
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Abstract
The indications for the benzodiazepines include anxiety, insomnia, muscle spasm and epilepsy and each disorder has a variety of biological substrates. Limbic structures and the neurotransmitters noradrenaline, 5-HT and GABA have all been implicated. Benzodiazepines act on allosteric receptor sites and potentiate the actions of GABA in modulating chloride ionophores across nerve membranes. These effects can be blocked by the benzodiazepine antagonist, flumazenil. The molecular pharmacology of the benzodiazepine-GABA-chloride receptor is complex, with a wide range of different subunits. Animal models of dependence have suggested that the changes associated with long-term benzodiazepine use are related more to receptor-effector coupling than to the receptor characteristics themselves. Thus, benzodiazepine agonists on long-term use lose their efficacy, antagonists become partial inverse antagonists, and inverse agonists increase in efficacy. Various clinical implications are explored, including the use of flumazenil to prevent and to treat benzodiazepine withdrawal syndromes.
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Affiliation(s)
- M Lader
- Institute of Psychiatry, London, UK
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