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Artigas F, Schenker E, Celada P, Spedding M, Lladó-Pelfort L, Jurado N, Núñez M, Santana N, Troyano-Rodriguez E, Riga MS, van den Munkhof H, Castañé A, Shaban H, Jay TM, Tripathi A, Godsil BP, Sebban C, Mariani J, Faure P, Takkilah S, Hughes ZA, Siok CJ, Hajos M, Wicke K, Gass N, Weber-Fahr W, Sartorius A, Becker R, Didriksen M, Bastlund JF, Tricklebank M, Risterucci C, Meyer-Lindenberg A, Schwarz AJ. Defining the brain circuits involved in psychiatric disorders: IMI-NEWMEDS. Nat Rev Drug Discov 2016; 16:1-2. [DOI: 10.1038/nrd.2016.205] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Alsiö J, Nilsson SRO, Gastambide F, Wang RAH, Dam SA, Mar AC, Tricklebank M, Robbins TW. The role of 5-HT2C receptors in touchscreen visual reversal learning in the rat: a cross-site study. Psychopharmacology (Berl) 2015; 232:4017-31. [PMID: 26007324 PMCID: PMC4600472 DOI: 10.1007/s00213-015-3963-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 05/07/2015] [Indexed: 02/02/2023]
Abstract
RATIONALE Reversal learning requires associative learning and executive functioning to suppress non-adaptive responding. Reversal-learning deficits are observed in e.g. schizophrenia and obsessive-compulsive disorder and implicate neural circuitry including the orbitofrontal cortex (OFC). Serotonergic function has been strongly linked to visual reversal learning in humans and experimental animals but less is known about which receptor subtypes are involved. OBJECTIVES The objectives of the study were to test the effects of systemic and intra-OFC 5-HT2C-receptor antagonism on visual reversal learning in rats and assess the psychological mechanisms underlying these effects within novel touchscreen paradigms. METHODS In experiments 1-2, we used a novel 3-stimulus task to investigate the effects of 5-HT2C-receptor antagonism through SB 242084 (0.1, 0.5 and 1.0 mg/kg i.p.) cross-site. Experiment 3 assessed the effects of SB 242084 in 2-choice reversal learning. In experiment 4, we validated a novel touchscreen serial visual reversal task suitable for neuropharmacological microinfusions by baclofen-/muscimol-induced OFC inactivation. In experiment 5, we tested the effect of intra-OFC SB 242084 (1.0 or 3.0 μg/side) on performance in this task. RESULTS In experiments 1-3, SB 242084 reduced early errors but increased late errors to criterion. In experiment 5, intra-OFC SB 242084 reduced early errors without increasing late errors in a reversal paradigm validated as OFC dependent (experiment 4). CONCLUSION Intra-OFC 5-HT2C-receptor antagonism decreases perseveration in novel touchscreen reversal-learning paradigms for the rat. Systemic 5-HT2C-receptor antagonism additionally impairs late learning-a robust effect observed cross-site and potentially linked to impulsivity. These conclusions are discussed in terms of neural mechanisms underlying reversal learning and their relevance to psychiatric disorders.
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Affiliation(s)
- J Alsiö
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK.
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK.
- Department of Neuroscience, Unit of Functional Neurobiology, University of Uppsala, Uppsala, SE-75124, Sweden.
| | - S R O Nilsson
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
| | - F Gastambide
- Lilly Centre for Cognitive Neuroscience, Eli Lilly & Co. Ltd., Erl Wood Manor, Windlesham, GU20 6PH, UK
| | - R A H Wang
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
| | - S A Dam
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
| | - A C Mar
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
| | - M Tricklebank
- Lilly Centre for Cognitive Neuroscience, Eli Lilly & Co. Ltd., Erl Wood Manor, Windlesham, GU20 6PH, UK
| | - T W Robbins
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, CB2 3EB, UK
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Francois J, Gastambide F, Conway MW, Tricklebank M, Gilmour G. Dissociation of mGlu2/3 agonist effects on ketamine-induced regional and event-related oxygen signals. Psychopharmacology (Berl) 2015; 232:4219-29. [PMID: 25943169 DOI: 10.1007/s00213-015-3948-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/20/2015] [Indexed: 12/22/2022]
Abstract
RATIONALE Validating preclinical biomarkers that predict treatment efficacy remains a critical imperative for neuropsychiatric drug discovery. With the establishment of novel in vivo imaging methods, it has become possible to think how such translational proof-of-concept studies may look. OBJECTIVES The aim of this study was to use in vivo oxygen (O2) amperometry to simultaneously assess the regional and event/task-related O2 changes induced by ketamine challenge in rats, and to determine whether both of these signals are equivalently affected by the mGlu2/3 receptor agonist LY379268. METHODS O2 signals were measured via carbon paste electrodes implanted in the anterior cingulate cortex (ACC) of rats trained to perform a simple reaction time task (SRT). SRT performance, event-related ACC O2 responses, and regional ACC O2 signal were recorded simultaneously in animals treated with ketamine (10 mg/kg) and/or LY379268 (3 mg/kg). RESULTS A consistent relationship was observed between baseline SRT performance and related ACC O2 signals, suggesting that ACC engagement is likely to be a requirement for optimal task performance. Ketamine induced a robust and consistent slowing in reaction times that was reflected by a delayed event-related ACC O2 signal increase compared to vehicle controls. Ketamine also produced a regional and task-independent 60-min increase in ACC O2 levels which was effectively attenuated by LY379268. However, LY379238 failed to reverse alterations in event-related O2 signals and associated SRT task performance. CONCLUSIONS These findings raise questions about the degree to which such reversals of regional ketamine O2 signals could potentially be claimed to predict drug treatment efficacy.
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Affiliation(s)
- Jennifer Francois
- In Vivo Pharmacology, Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, England, UK
| | - Francois Gastambide
- In Vivo Pharmacology, Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, England, UK.
| | - Michael Warwick Conway
- In Vivo Pharmacology, Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, England, UK
| | - Mark Tricklebank
- In Vivo Pharmacology, Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, England, UK
| | - Gary Gilmour
- In Vivo Pharmacology, Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, England, UK
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Loomis S, McCarthy A, Baxter C, Kellett DO, Edgar DM, Tricklebank M, Gilmour G. Distinct pro-vigilant profile induced in rats by the mGluR5 potentiator LSN2814617. Psychopharmacology (Berl) 2015; 232:3977-89. [PMID: 25902875 PMCID: PMC4600478 DOI: 10.1007/s00213-015-3936-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/02/2015] [Indexed: 12/30/2022]
Abstract
While treatment options are available, excessive daytime sleepiness (EDS) remains a significant unmet medical need for many patients. Relatively little rodent behavioural pharmacology has been conducted in this context to assess potential pro-vigilant compounds for their ability to restore functional capacity following experimentally induced sleep loss. Male Wistar rats were prepared for electroencephalographic (EEG) recording and subject to 11 h of sleep restriction using a biofeedback-induced cage rotation protocol. A simple response latency task (SRLT) was used to behaviourally index sleep restriction and the effects of pro-vigilant compounds: modafinil, D-amphetamine, caffeine, and the mGlu5-positive allosteric modulator LSN2814617. Sleep restriction resulted in a consistent, quantified loss of non-rapid eye movement (NREM) and REM sleep that impaired SRLT performance in a manner suggestive of progressive task disengagement. In terms of EEG parameters, all compounds induced wakefulness. Amphetamine treatment further decreased SRLT performance capacity, whereas the other three compounds decreased omissions and allowed animals to re-engage in the task. Caffeine and modafinil also significantly increased premature responses during this period, an effect not observed for LSN2814617. While all compounds caused compensatory sleep responses, the magnitude of compensation observed for LSN2814617 was much smaller than would be predicted to result from the prolongation of wakefulness exhibited. Using simple response latencies to index performance, an mGlu5 PAM dramatically increased wakefulness and improved functional capacity of sleep-restricted animals, without eliciting a proportionate compensatory sleep response. This effect was qualitatively distinct from that of amphetamine, caffeine and modafinil.
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Affiliation(s)
- Sally Loomis
- Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH England UK
| | - Andrew McCarthy
- Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH England UK
| | - Christopher Baxter
- Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH England UK
| | - Daniel O. Kellett
- Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH England UK
| | - Dale M. Edgar
- Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH England UK
| | - Mark Tricklebank
- Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH England UK
| | - Gary Gilmour
- Lilly Research Laboratories, Eli Lilly & Co. Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, England, UK.
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Wesseling H, Rahmoune H, Tricklebank M, Guest PC, Bahn S. A Targeted Multiplexed Proteomic Investigation Identifies Ketamine-Induced Changes in Immune Markers in Rat Serum and Expression Changes in Protein Kinases/Phosphatases in Rat Brain. J Proteome Res 2014; 14:411-21. [DOI: 10.1021/pr5009493] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Hendrik Wesseling
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom
| | - Hassan Rahmoune
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom
| | - Mark Tricklebank
- Ely Lilly
and
Co. Ltd, Erl Wood Manor, Sunninghill
Road, Windelesham, Surrey GU20 6PH, United Kingdom
| | - Paul C. Guest
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom
| | - Sabine Bahn
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom
- Department
of Neuroscience, Erasmus Medical Center Rotterdam, 3000 CA, The Netherlands
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Li J, Ishiwari K, Conway MW, Francois J, Huxter J, Lowry JP, Schwarz AJ, Tricklebank M, Gilmour G. Dissociable effects of antipsychotics on ketamine-induced changes in regional oxygenation and inter-regional coherence of low frequency oxygen fluctuations in the rat. Neuropsychopharmacology 2014; 39:1635-44. [PMID: 24442094 PMCID: PMC4023136 DOI: 10.1038/npp.2014.10] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 01/13/2014] [Accepted: 01/14/2014] [Indexed: 11/08/2022]
Abstract
Typical and atypical antipsychotics have been shown to alleviate N-methyl-D-aspartate (NMDA) receptor antagonist-induced BOLD signals in healthy humans and animals to differing degrees; factors that might relate to their different molecular mechanisms and clinical profiles. Recent studies have also extended these investigations to the analysis of resting state functional connectivity measures of BOLD signals in different brain regions. Using constant potential amperometry, we examined the effects of the NMDA receptor antagonist S-(+)-ketamine on tissue oxygen levels in medial prefrontal cortex (mPFC) and medial ventral striatum (mVS), and temporal coherence of low-frequency oxygen fluctuations between these regions in freely moving rats. Furthermore, we assessed the extent to which the atypical antipsychotic clozapine and the typical antipsychotic haloperidol could modulate the effects of S-(+)-ketamine on these measures. Acute S-(+)-ketamine (5-25 mg/kg) produced dose-dependent increases in both tissue O2 levels and coherence. Although effects of clozapine and haloperidol alone were relatively minor, their effects on ketamine-induced signals were markedly more distinct. Clozapine dose-dependently attenuated the absolute S-(+)-ketamine (25 mg/kg) O2 signal in both regions, and also attenuated ketamine-induced increases in regional coherence. Haloperidol had no effect on the absolute ketamine O2 signal yet potentiated increases in regional coherence. The dissociable effects of haloperidol and clozapine on ketamine-induced hyperoxygenation and mPFC-mVS coherence elucidate potentially important mechanistic differences between these classes of pharmacology. This study demonstrates for the first time that in vivo amperometry can measure both regional brain tissue O2 levels and inter-regional coherence, advancing BOLD-like measurements of functional connectivity into awake, unconstrained animals.
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Affiliation(s)
- Jennifer Li
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
| | - Keita Ishiwari
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
- Department of Chemistry, National University of Ireland, Maynooth, Co. Kildare, Ireland
| | - Michael W Conway
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
| | - Jennifer Francois
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
| | - John Huxter
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
| | - John P Lowry
- Department of Chemistry, National University of Ireland, Maynooth, Co. Kildare, Ireland
| | - Adam J Schwarz
- Tailored Therapeutics, Eli Lilly and Company, Indianapolis, IN, USA
| | - Mark Tricklebank
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
| | - Gary Gilmour
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
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Loomis S, Mccarthy A, Edgar D, Tricklebank M, Gilmour G. Behavioural evidence that modafinil and amphetamine do not produce equivalent qualities of wake promotion in sleep-restricted rats. Sleep Med 2013. [DOI: 10.1016/j.sleep.2013.11.436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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McHugh SB, Marques-Smith A, Li J, Rawlins JNP, Lowry J, Conway M, Gilmour G, Tricklebank M, Bannerman DM. Hemodynamic responses in amygdala and hippocampus distinguish between aversive and neutral cues during Pavlovian fear conditioning in behaving rats. Eur J Neurosci 2012; 37:498-507. [PMID: 23173719 PMCID: PMC3638322 DOI: 10.1111/ejn.12057] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 10/12/2012] [Accepted: 10/13/2012] [Indexed: 12/11/2022]
Abstract
Lesion and electrophysiological studies in rodents have identified the amygdala and hippocampus (HPC) as key structures for Pavlovian fear conditioning, but human functional neuroimaging studies have not consistently found activation of these structures. This could be because hemodynamic responses cannot detect the sparse neuronal activity proposed to underlie conditioned fear. Alternatively, differences in experimental design or fear levels could account for the discrepant findings between rodents and humans. To help distinguish between these alternatives, we used tissue oxygen amperometry to record hemodynamic responses from the basolateral amygdala (BLA), dorsal HPC (dHPC) and ventral HPC (vHPC) in freely-moving rats during the acquisition and extinction of conditioned fear. To enable specific comparison with human studies we used a discriminative paradigm, with one auditory cue [conditioned stimulus (CS)+] that was always followed by footshock, and another auditory cue (CS-) that was never followed by footshock. BLA tissue oxygen signals were significantly higher during CS+ than CS- trials during training and early extinction. In contrast, they were lower during CS+ than CS- trials by the end of extinction. dHPC and vHPC tissue oxygen signals were significantly lower during CS+ than CS- trials throughout extinction. Thus, hemodynamic signals in the amygdala and HPC can detect the different patterns of neuronal activity evoked by threatening vs. neutral stimuli during fear conditioning. Discrepant neuroimaging findings may be due to differences in experimental design and/or fear levels evoked in participants. Our methodology offers a way to improve translation between rodent models and human neuroimaging.
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Affiliation(s)
- Stephen B McHugh
- Department of Experimental Psychology, University of Oxford, Oxford, UK.
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Phillips K, Cotel M, McCarthy A, Edgar D, Tricklebank M, O’Neill M, Jones M, Wafford K. Differential effects of NMDA antagonists on high frequency and gamma EEG oscillations in a neurodevelopmental model of schizophrenia. Neuropharmacology 2012; 62:1359-70. [DOI: 10.1016/j.neuropharm.2011.04.006] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 04/01/2011] [Accepted: 04/08/2011] [Indexed: 01/01/2023]
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Gilmour G, Dix S, Fellini L, Gastambide F, Plath N, Steckler T, Talpos J, Tricklebank M. NMDA receptors, cognition and schizophrenia – Testing the validity of the NMDA receptor hypofunction hypothesis. Neuropharmacology 2012; 62:1401-12. [DOI: 10.1016/j.neuropharm.2011.03.015] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 03/10/2011] [Accepted: 03/12/2011] [Indexed: 11/25/2022]
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Smith JW, Gastambide F, Gilmour G, Dix S, Foss J, Lloyd K, Malik N, Tricklebank M. A comparison of the effects of ketamine and phencyclidine with other antagonists of the NMDA receptor in rodent assays of attention and working memory. Psychopharmacology (Berl) 2011; 217:255-69. [PMID: 21484239 DOI: 10.1007/s00213-011-2277-5] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 03/22/2011] [Indexed: 01/13/2023]
Abstract
RATIONALE N-methyl-D: -Aspartate receptor (NMDAR) antagonists such as ketamine induce cognitive symptoms in man similar to those of schizophrenia and therefore might be useful as models of the disease in animals. However, it is unclear which NMDAR antagonist(s) offer the best means to produce cognitive deficits in attention and working memory and to what extent those deficits can be measured selectively in rats. OBJECTIVES The present study systematically compared the effects of eight different NMDAR antagonists-MK-801, phencyclidine, (S)-(+)-ketamine, memantine, SDZ-220,581, Ro 25-6981, CP 101-606 and NVP-AAM077-in rats using standard tests of visual attention, the five-choice serial reaction time task (5CSRT), and working memory, the delayed matching to position task (DMTP). RESULTS Drug-induced responses varied qualitatively and quantitatively in both a compound- and a task-dependent manner. Effects were generally confounded by concomitant motor and motivational disruption, although individual doses of phencyclidine for example appeared to impair selectively cognitive functions. Interestingly, GluN2B selective antagonists were unique in their effects; inducing potential performance benefit in the 5CSRT. CONCLUSIONS Overall, the opportunity to induce a selective cognitive deficit in attention (5CSRT) or working memory (DMTP) in the rat is limited by both the NMDAR antagonist and the dose range used. The importance of a preclinical focus on ketamine, which is used more frequently in clinical settings, is limited by the extent to which cognitive effects can be both detected and quantified using this exposure regimen within these two operant assays.
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Affiliation(s)
- Janice W Smith
- Lilly Centre for Cognitive Neuroscience, Lilly Research Laboratories, Eli Lilly & Co. Ltd., Erl Wood Manor, Sunninghill Road, Windlesham, Surrey, GU20 6PH, UK
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Tricklebank M. Excitatory Amino Acid Receptors. Design of Agonists and Antagonists. J Pharm Pharmacol 2011. [DOI: 10.1111/j.2042-7158.1993.tb05654.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bolger FB, McHugh SB, Bennett R, Li J, Ishiwari K, Francois J, Conway MW, Gilmour G, Bannerman DM, Fillenz M, Tricklebank M, Lowry JP. Characterisation of carbon paste electrodes for real-time amperometric monitoring of brain tissue oxygen. J Neurosci Methods 2010; 195:135-42. [PMID: 21115045 DOI: 10.1016/j.jneumeth.2010.11.013] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Revised: 11/11/2010] [Accepted: 11/21/2010] [Indexed: 12/12/2022]
Abstract
Tissue O₂ can be monitored using a variety of electrochemical techniques and electrodes. In vitro and in vivo characterisation studies for O₂ reduction at carbon paste electrodes (CPEs) using constant potential amperometry (CPA) are presented. Cyclic voltammetry indicated that an applied potential of -650 mV is required for O₂ reduction at CPEs. High sensitivity (-1.49 ± 0.01 nA/μM), low detection limit (ca. 0.1 μM) and good linear response characteristics (R² > 0.99) were observed in calibration experiments performed at this potential. There was also no effect of pH, temperature, and ion changes, and no dependence upon flow/fluid convection (stirring). Several compounds (e.g. dopamine and its metabolites) present in brain extracellular fluid were tested at physiological concentrations and shown not to interfere with the CPA O₂ signal. In vivo experiments confirmed a sub-second response time observed in vitro and demonstrated long-term stability extending over twelve weeks, with minimal O₂ consumption (ca. 1 nmol/h). These results indicate that CPEs operating amperometrically at a constant potential of -650 mV (vs. SCE) can be used reliably to continuously monitor brain extracellular tissue O₂.
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Affiliation(s)
- Fiachra B Bolger
- Department of Chemistry, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland
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Dix S, Gilmour G, Potts S, Smith JW, Tricklebank M. A within-subject cognitive battery in the rat: differential effects of NMDA receptor antagonists. Psychopharmacology (Berl) 2010; 212:227-42. [PMID: 20676612 DOI: 10.1007/s00213-010-1945-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Accepted: 06/29/2010] [Indexed: 10/19/2022]
Abstract
RATIONALE The range of cognitive and psychotomimetic effects produced by antagonists of the N-methyl-D-aspartate (NMDA) receptor has lead to widespread usage of these molecules as pharmacological models of cognitive impairment for drug discovery. Historically, NMDA receptor antagonists have been used interchangeably on the assumption that they produce analogous effects. OBJECTIVES To profile a subset of these antagonists across a novel within-subject cognitive battery in the rat. METHODS Naïve male Lister Hooded rats were subjected to a series of tests in which they were required to learn a simple visuo-auditory conditional discrimination. They then underwent testing in a delayed discrimination test followed by rule reversal and rule extinction tests. RESULTS All NMDA receptor antagonists tested impaired acquisition performance and, with the exception of ketamine and the GluN2A preferring antagonist, NVP-AAM077, impaired consolidation of extinction. GluN2B antagonism produced a singular profile with potentially enhanced delayed discrimination performance and reduced hit rates in the reversal phase. Only PCP (phencyclidine) and ketamine disrupted performance in the delay phase but did so in a delay-independent manner. MK-801, PCP and memantine all increased the hit rate in the reversal phase; whilst only MK-801 and PCP impaired extinction per se. CONCLUSIONS NMDA receptor-dependent mechanisms are requisite in the acquisition of a simple conditional discrimination and consolidation of extinction. Their role in working memory and reversal tasks appear to be less critical and potentially specific to the paradigm and NMDA receptor antagonist used. It is clearly misleading to generalise across NMDA antagonists with respect to their preclinical cognitive profile.
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Affiliation(s)
- Sophie Dix
- Lilly Centre for Cognitive Neuroscience, Eli Lilly and Co Ltd, Erl Wood Manor, Sunninghill Road, Windlesham, Surrey GU20 6PH, UK.
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Lowry JP, Griffin K, McHugh SB, Lowe AS, Tricklebank M, Sibson NR. Real-time electrochemical monitoring of brain tissue oxygen: A surrogate for functional magnetic resonance imaging in rodents. Neuroimage 2010; 52:549-55. [DOI: 10.1016/j.neuroimage.2010.04.187] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 03/27/2010] [Accepted: 04/15/2010] [Indexed: 10/19/2022] Open
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Zain ZM, O’Neill RD, Lowry JP, Pierce KW, Tricklebank M, Dewa A, Ghani SA. Development of an implantable d-serine biosensor for in vivo monitoring using mammalian d-amino acid oxidase on a poly (o-phenylenediamine) and Nafion-modified platinum–iridium disk electrode. Biosens Bioelectron 2010; 25:1454-9. [DOI: 10.1016/j.bios.2009.10.049] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 10/29/2009] [Accepted: 10/29/2009] [Indexed: 10/20/2022]
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Jones N, Messenger MJ, O'Neill MJ, Oldershaw A, Gilmour G, Simmons RMA, Iyengar S, Libri V, Tricklebank M, Williams SCR. AMPA receptor potentiation can prevent ethanol-induced intoxication. Neuropsychopharmacology 2008; 33:1713-23. [PMID: 17851540 DOI: 10.1038/sj.npp.1301562] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We present a substantial series of behavioral and imaging experiments, which demonstrate, for the first time, that increasing AMPA receptor-mediated neurotransmission via administration of potent and selective biarylsulfonamide AMPA potentiators LY404187 and LY451395 reverses the central effects of an acutely intoxicating dose of ethanol in the rat. Using pharmacological magnetic resonance imaging (phMRI), we observed that LY404187 attenuated ethanol-induced reductions in blood oxygenation level dependent (BOLD) in the anesthetized rat brain. A similar attenuation was apparent when measuring local cerebral glucose utilization (LCGU) via C14-2-deoxyglucose autoradiography in freely moving conscious rats. Both LY404187 and LY451395 significantly and dose-dependently reversed ethanol-induced deficits in both motor coordination and disruptions in an operant task where animals were trained to press a lever for food reward. Both prophylactic and acute intervention treatment with LY404187 reversed ethanol-induced deficits in motor coordination. Given that LY451395 and related AMPA receptor potentiators/ampakines are tolerated in both healthy volunteers and elderly patients, these data suggest that such compounds may form a potential management strategy for acute alcohol intoxication.
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Affiliation(s)
- Nicholas Jones
- Neuroimaging Research Group, Institute of Psychiatry, Kings College London, London, UK.
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Smith JW, Mogg A, Tafi E, Peacey E, Pullar IA, Szekeres P, Tricklebank M. Ligands selective for alpha4beta2 but not alpha3beta4 or alpha7 nicotinic receptors generalise to the nicotine discriminative stimulus in the rat. Psychopharmacology (Berl) 2007; 190:157-70. [PMID: 17115136 DOI: 10.1007/s00213-006-0596-8] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Accepted: 09/19/2006] [Indexed: 02/06/2023]
Abstract
RATIONALE Nicotine produces behavioural effects that are potentially related to its interaction with diverse nicotinic acetylcholine receptor populations. Evidence from gene deletion studies suggests that the interoceptive stimulus properties of nicotine are mediated by heteromeric high-affinity receptors containing alpha4beta2 subunits. Mice lacking beta2 subunits do not discriminate nicotine (Shoaib et al., Neuropharmacology, 42:530-539, 2002), and nicotine does not elicit dopamine release in these animals (Grady et al., J Neurochem, 76:258-268, 2001). The stimulus properties of nicotine can be detected in rats using a two-lever operant drug discrimination paradigm, allowing them to be classified pharmacologically using ligands with selectivity for receptors containing alpha4beta2, alpha3beta4 or alpha7 subunits. MATERIALS AND METHODS Rats trained to discriminate 0.4 mg/kg nicotine from vehicle were given the nicotinic receptor agonists, cytisine, varenicline, TC2559, ABT-594, A-85380 (all having high affinity but varying selectivity for alpha4beta2-containing receptors), and WO 03/062224 and WO 01/60821A1 (selective for beta4- and alpha7-containing receptors, respectively). In separate studies, WO 03/062224 was used as the training stimulus. RESULTS Nicotine, TC-2559, A-85380 and ABT-594 showed dose-dependent and complete stimulus substitution, whilst WO 03/062224 and WO 01/60821A1 were completely without effect. Cytisine and varenicline showed partial generalisation, consistent with their partial agonist activity at nicotinic receptors eliciting dopamine release in rat striatal slices. After almost 50 training sessions with WO 03/062224, there was no clear evidence that an alpha3beta4 receptor agonist could sustain a discriminable stimulus. CONCLUSION Substitution to the nicotine discriminative stimulus required high-affinity and high intrinsic activity at beta2 but not at beta4- or at alpha7-containing nicotinic receptors.
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Affiliation(s)
- Janice W Smith
- Eli Lilly & Co Ltd, Lilly Research Centre, Sunninghill Road, Windlesham, Surrey, UK.
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Littlewood CL, Cash D, Dixon AL, Dix SL, White CT, O'Neill MJ, Tricklebank M, Williams SCR. Using the BOLD MR signal to differentiate the stereoisomers of ketamine in the rat. Neuroimage 2006; 32:1733-46. [PMID: 16815040 DOI: 10.1016/j.neuroimage.2006.05.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 04/10/2006] [Accepted: 05/03/2006] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Ketamine is a chiral molecule that is reported to model aspects of schizophrenia. OBJECTIVES To investigate the stereospecificity of the isomers of ketamine using pharmacological magnetic resonance imaging (phMRI) in order to further understand ketamine's pharmacodynamic actions. METHOD Responses to 25 mg kg-1S(+) isomer, R(-) isomer and racemic ketamine in independent groups of Sprague-Dawley rats were investigated using a prepulse inhibition paradigm, locomotor observations, MRI and 2-deoxyglucose techniques. RESULTS Racemic ketamine and the S(+) isomer were both capable of disrupting sensorimotor gating as measured using prepulse inhibition and produced a longer period of hyperlocomotion comparative to the R(-) isomer. In contrast, large alterations in the BOLD MR signal were observed with R(-) isomer, whereas S(+) isomer and racemate precipitated more localized BOLD signal changes predominantly in cortical, hippocampal and hindbrain regions. Glucose utilization rates in conscious animals are in agreement with previously published data and verify the BOLD responses in the racemic group. However, no significant changes in glucose utilization were observed in the anesthetized cohort. CONCLUSIONS Ketamine and its isomers have stereospecific effects on sensorimotor gating and locomotion that correlate with the enantiomer's affinity for the NMDA receptor. It would appear that anesthesia, as required for preclinical MRI procedures, may interact with and potentially attenuate the drug's response. Although analysis of the main effect of isomers in comparison to each other or the racemate offers an alternative analysis method that should be less susceptible to anesthetic interactions, only the R(-) isomer comparative to the racemate offers significant differences of interest.
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Affiliation(s)
- Clare L Littlewood
- King's College London, Neuroimaging Research Group, Institute of Psychiatry, PO42 De Crespigny Park, London SE5 8AF, UK.
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Littlewood CL, Jones N, O'Neill MJ, Mitchell SN, Tricklebank M, Williams SCR. Mapping the central effects of ketamine in the rat using pharmacological MRI. Psychopharmacology (Berl) 2006; 186:64-81. [PMID: 16550385 DOI: 10.1007/s00213-006-0344-0] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Accepted: 01/23/2006] [Indexed: 02/02/2023]
Abstract
RATIONALE Ketamine induces, in both humans and rodents, behaviours analogous to some of the symptoms of schizophrenia. OBJECTIVES To utilise pharmacological magnetic resonance imaging (phMRI) techniques that identify changes in blood-oxygenation-level-dependent (BOLD) contrast to determine the temporal and spatial neuronal activation profile of ketamine in the rat brain. METHOD To obtain a pharmacodynamic profile of the drug, we assessed changes in locomotor activity after vehicle and 10 and 25 mg/kg ketamine. Separate animals were then anaesthetised and placed in a 4.7-T magnetic resonance (MR) system before receiving the same doses of ketamine during serial MR image acquisition. Subsequent statistical parametric mapping of the main effect of the drug was then undertaken to identify changes in BOLD contrast. Levels of gamma-aminobutyric acid (GABA) and dopamine (DA) in brain areas showing localised changes in BOLD contrast were then assessed via microdialysis. RESULTS Both doses of ketamine produced increases in BOLD image contrast in frontal, hippocampal, cortical and limbic areas. A further investigation of the release of DA and its metabolites in the nucleus accumbens, both in anaesthesised and freely moving rats, corroborated these findings. However, an investigation of GABA and DA levels in the ventral pallidum gave no indication of changes in activity. CONCLUSIONS Ketamine produced localised dose-dependent alterations in BOLD MR signal, which correlate with the pharmacodynamic profile of the drug. These results can be, at least, partially substantiated with complementary techniques but consideration must be given to the input function applied to the MR signal and the use of anaesthesia during phMRI experimentation.
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Affiliation(s)
- Clare L Littlewood
- Neuroimaging Research Group, Institute of Psychiatry, King's College, London, De Crespigny Park, London, SE5 8AF, UK.
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Jones N, O'Neill MJ, Tricklebank M, Libri V, Williams SCR. Examining the neural targets of the AMPA receptor potentiator LY404187 in the rat brain using pharmacological magnetic resonance imaging. Psychopharmacology (Berl) 2005; 180:743-51. [PMID: 15864556 DOI: 10.1007/s00213-005-2254-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2004] [Accepted: 02/23/2005] [Indexed: 01/23/2023]
Abstract
RATIONALE Drugs that enhance alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropanoic acid (AMPA) receptor-mediated glutamatergic transmission, such as the AMPA receptor potentiator LY404187, may form treatment strategies for disorders of cognition, learning and memory. OBJECTIVES Pharmacological magnetic resonance imaging (phMRI) uses blood oxygenation level dependent (BOLD) contrast as a marker of neuronal activity and allows dynamic non-invasive in vivo imaging of the effects of CNS-active compounds. This study used phMRI to examine the effects of LY404187 in the rat brain. METHOD Groups of Sprague Dawley rats (n=7) were anaesthetised and placed in a 4.7 Tesla superconducting magnet before receiving an acute dose of LY404187 (0.5 mg/kg s.c.), either alone or after pretreatment with the selective AMPA/kainate antagonist LY293558 (15 mg/kg s.c.), or LY293558 alone (15 mg/kg s.c.). Brain images were acquired for each subject every minute for 180 min. These volumes were extensively pre-processed before being analysed for changes in BOLD contrast. RESULTS LY404187 produced significant increases in BOLD contrast in brain regions including the hippocampus, lateral and medial habenulae and superior and inferior colliculi. These changes were blocked by LY293558. When administered alone, LY293558 caused widespread decreases in BOLD contrast. CONCLUSIONS The known actions of LY404187 suggest the observed BOLD signal increases reflect increases in excitatory neurotransmission. The decreases in signal following LY293558 alone are harder to interpret and are discussed in terms of the negative BOLD response. This study provides the first evidence that the effects of AMPA receptor-mediating compounds can be observed using phMRI.
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Affiliation(s)
- Nicholas Jones
- Neuroimaging Research Group, Institute of Psychiatry, De Crespigny Park, London, SE5 8AF, UK.
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Gazi L, Bobirnac I, Danzeisen M, Schüpbach E, Langenegger D, Sommer B, Hoyer D, Tricklebank M, Schoeffter P. Receptor density as a factor governing the efficacy of the dopamine D4 receptor ligands, L-745,870 and U-101958 at human recombinant D4.4 receptors expressed in CHO cells. Br J Pharmacol 1999; 128:613-20. [PMID: 10516640 PMCID: PMC1571689 DOI: 10.1038/sj.bjp.0702849] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/1999] [Revised: 07/13/1999] [Accepted: 07/21/1999] [Indexed: 11/09/2022] Open
Abstract
1. The relationships between the density of dopamine D4.4 receptors and the agonist efficacies of L-745,870 (3-(4-[4-chlorophhenyl]piperazin-1-yl)-methyl-1H-pyrrolo [2, 3-b]pyridine) and U-101958 ((1-benzyl-piperidin-4-yl)-(3-isopropoxy-pyridin-2-yl)-methyl-a min e) were investigated in Chinese hamster ovary (CHO) cells, after treatment with the gene expression enhancer, sodium butyrate. 2. In CHO cells expressing D4.4 receptors (CHO/D4 cells), dopamine inhibited forskolin-stimulated cyclic AMP accumulation (Emax 56+/-1% inhibition, pEC50 7.4+/-0.1, n=10). U-101958 behaved as a partial agonist (39+/-7% the efficacy of dopamine, pEC50 8.1+/-0.3, n=4), whereas L-745,870 had no detectable agonist effect. 3. Receptor density, as estimated by [3H]-spiperone saturation binding was 240+/-30 fmol mg-1 protein (n=8) in CHO/D4 cell homogenates. It reached 560+/-150 (n=6), 1000+/-190 (n=4) and 840+/-120 (n=4) fmol mg-1 protein after treatment with sodium butyrate (5 mM) for 6, 18 and 48 h, respectively. 4. The increase in receptor density was associated with a gradual enhancement of the agonist effects (increased Emax and pEC50 values) of dopamine. The efficacy of U-101958 (relative to dopamine) doubled and L-745,870 was turned into a partial agonist (efficacy 49% relative to dopamine, pEC50 8. 6+/-0.2, n=6, after 48 h treatment with sodium butyrate). These agonist effects of U-101958 and L-745,870 could be antagonized by spiperone (0.1 microM) but not by raclopride (10 microM). 5. The results show that U-101958 and L-745,870 are partial agonists at human dopamine D4.4 receptors expressed in CHO cells. Their efficacy is governed by receptor density. Agonist effects of these two compounds in vivo cannot be excluded under circumstances of increased receptor levels.
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Affiliation(s)
- L Gazi
- Nervous System Therapeutic Area, Novartis Pharma Research, Novartis Pharma Inc., CH-4002 Basel, Switzerland
| | - I Bobirnac
- Nervous System Therapeutic Area, Novartis Pharma Research, Novartis Pharma Inc., CH-4002 Basel, Switzerland
| | - M Danzeisen
- Nervous System Therapeutic Area, Novartis Pharma Research, Novartis Pharma Inc., CH-4002 Basel, Switzerland
| | - E Schüpbach
- Nervous System Therapeutic Area, Novartis Pharma Research, Novartis Pharma Inc., CH-4002 Basel, Switzerland
| | - D Langenegger
- Nervous System Therapeutic Area, Novartis Pharma Research, Novartis Pharma Inc., CH-4002 Basel, Switzerland
| | - B Sommer
- Nervous System Therapeutic Area, Novartis Pharma Research, Novartis Pharma Inc., CH-4002 Basel, Switzerland
| | - D Hoyer
- Nervous System Therapeutic Area, Novartis Pharma Research, Novartis Pharma Inc., CH-4002 Basel, Switzerland
| | - M Tricklebank
- Nervous System Therapeutic Area, Novartis Pharma Research, Novartis Pharma Inc., CH-4002 Basel, Switzerland
| | - P Schoeffter
- Nervous System Therapeutic Area, Novartis Pharma Research, Novartis Pharma Inc., CH-4002 Basel, Switzerland
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Bakshi VP, Tricklebank M, Neijt HC, Lehmann-Masten V, Geyer MA. Disruption of prepulse inhibition and increases in locomotor activity by competitive N-methyl-D-aspartate receptor antagonists in rats. J Pharmacol Exp Ther 1999; 288:643-52. [PMID: 9918570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
Noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonists such as phencyclidine are psychotomimetics and disrupt prepulse inhibition (PPI), a measure of sensorimotor gating that is deficient in schizophrenia. Systemically administered competitive NMDA receptor antagonists do not disrupt PPI in rats, leading to speculation that these compounds might have use as neuroprotective agents without the risk of psychotomimetic side effects. The effects on sensorimotor gating and locomotor activity of competitive NMDA receptor antagonists that either penetrate (SDZ 220-581 and SDZ EAB-515) or poorly penetrate [SDZ EAA-494 (D-CPPene)] the blood-brain barrier were compared. Rats were treated with either SDZ 220-581 (0, 2.5, or 5.0 mg/kg) or SDZ EAB-515 (0, 3.0, 10.0, or 30.0 mg/kg) and tested for PPI and locomotor activity. Different rats were tested for PPI after either systemic (0, 0.5, 1.0, or 5.0 mg/kg) or intra-amygdala (0 or 1.0 microg/microl) administration of D-CPPene. Finally, rats were pretreated with clozapine (0 or 5.0 mg/kg) or haloperidol (0 or 0.1 mg/kg), together with SDZ 220-581 (0 or 2.5 mg/kg), and tested. SDZ 220-581 and SDZ EAB-515 decreased PPI without affecting startle magnitude. Reduced PPI was noted after central but not systemic administration of D-CPPene. The gating deficits produced by SDZ 220-581 were blocked by clozapine or haloperidol. Movement pattern analysis indicated that locomotor activity was increased by SDZ 220-581 and SDZ EAB-515 in a phencyclidine-like manner. These results indicate that competitive NMDA receptor antagonists, if they gain sufficient access to the brain, produce a behavioral profile that resembles that of the psychotomimetic noncompetitive antagonists.
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Affiliation(s)
- V P Bakshi
- Program in Neurosciences, University of California at San Diego, La Jolla 92093-0804, USA
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Gazi L, Bobirnac I, Danzeisen M, Schüpbach E, Bruinvels AT, Geisse S, Sommer B, Hoyer D, Tricklebank M, Schoeffter P. The agonist activities of the putative antipsychotic agents, L-745,870 and U-101958 in HEK293 cells expressing the human dopamine D4.4 receptor. Br J Pharmacol 1998; 124:889-96. [PMID: 9692773 PMCID: PMC1565470 DOI: 10.1038/sj.bjp.0701921] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
1. Dopamine D4 receptor antagonists are being developed by several pharmaceutical companies as putative novel antipsychotics, possibly with low propensity to side-effects. Two such compounds, L-745,870 and U-101958 have been recently introduced. 2. The radioligand binding and functional activities of L-745,870 and U-101958 were investigated in human embryonic kidney (HEK)293 cells expressing the human recombinant dopamine D4.4 receptor (HEK293/D4 cells). [3H]-spiperone binding experiments were performed and inhibition of forskolin-stimulated cyclic AMP accumulation was used as the functional response. 3. [3H]-spiperone was found to label a homogeneous and saturable population of specific binding sites in HEK293/D4 cell homogenates (Bmax 505+/-90 fmol mg(-1) protein, pK(D) 9.5+/-0.1, n=3). Inhibition of specific [3H]-spiperone binding was observed with spiperone (pKi 9.6+/-0.1, n=3), clozapine (pKi 7.4+/-0.1, n=4), L-745,870 (pKi 8.5+/-0.1, n=3) and U-101958 (pKi 8.9+/-0.1, n=3). By contrast, raclopride was very weak (pKi < 5, n=3). 4. Dopamine inhibited forskolin-stimulated cyclic AMP accumulation in HEK293/D4 cells in a concentration-dependent fashion (Emax 71+/-2% inhibition of forskolin-stimulated levels, pEC50 8.7+/-0.1, n=10). This effect was mimicked by the dopamine D2-like receptor agonists, quinpirole and 7-hydroxy-2-dipropylaminotetralin (7-OH-DPAT). 5. L-745,870 and U-101958 also inhibited forskolin-stimulated cyclic AMP accumulation in HEK293/D4 cells in a concentration-dependent way. L-745,870 was less efficacious than dopamine (71% the efficacy of dopamine), whereas U-101958 behaved as a full agonist compared to dopamine. Potencies (pEC50) values of L-745,870 and U-101958 were 9.0+/-0.2 (n=4) and 8.7+/-0.3 (n=3), consistent with pKi values determined in radioligand binding studies. 6. Dopamine, L-745,870 and U-101958 (up to 1 microM) were devoid of effect on forskolin-stimulated cyclic AMP accumulation in control, non-transfected HEK293 cells. 7. The agonist effects of dopamine, L-745,870 and U-101958 in HEK293/D4 cells could be antagonized by spiperone (pK(B) 8.2-8.8) and clozapine (pK(B) 7.1), but not by raclopride (pK(B) < 5). None of these antagonists had any significant agonist activity at concentrations up to 10 microM. 8. These results show that the putative dopamine D4 receptor antagonists, L-745,870 and U-101958 are not devoid of intrinsic activity at human recombinant dopamine D4.4 receptors. Therefore, they may not represent the most appropriate drugs for testing the benefit of D4 receptor antagonism in schizophrenic patients, if agonism should translate in vivo.
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Affiliation(s)
- L Gazi
- Nervous System Research, Novartis Pharma AG, Basel, Switzerland
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Jackson A, Tattersall D, Bentley G, Rycroft W, Bourson A, Hargreaves R, Tricklebank M, Iversen S. An investigation into the discriminative stimulus and reinforcing properties of the CCKB-receptor antagonist, L-365,260 in rats. Neuropeptides 1994; 26:343-53. [PMID: 8065550 DOI: 10.1016/0143-4179(94)90119-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The discriminative stimulus properties of the selective CCKB-receptor antagonist, L-365,260 were evaluated in rats trained to discriminate diazepam (2 mg/kg) or morphine (5 mg/kg) from vehicle, using a two-lever food reinforced technique. In the diazepam drug discrimination, the benzodiazepine-receptor agonist FG8205 (0.063-2 mg/kg) produced dose-related drug associated responding, whereas L-365,260 (0.125-4 mg/kg) treated animals showed vehicle appropriate behaviour. In rats trained to discriminate morphine from saline, L-365,260 (0.063-4 mg/kg) produced saline lever responding. When a dose of 1 mg/kg L-365,260 was administered in combination with morphine, the dose response curve for drug lever responding was not significantly affected. This was in contrast to the effect produced by the opiate antagonist naloxone (0.3 mg/kg) which shifted the dose-response curve to the right. Another group of rats underwent training to discriminate a dose of 6 mg/kg L-365,260 from vehicle. None of the animals learned the discrimination within 50 daily training sessions. In addition, unlike morphine (3 mg/kg), or changing the training dose of cocaine, intravenous administration of L-365,260 (0.3-10 mg/kg) did not modify lever pressing or the number of injections received by rats trained to self administer cocaine (0.25 mg/injection). L-365,260 (0.1-3 mg/kg) produced a dose-related inhibition of pentagastrin-stimulated gastric acid secretion in vivo. When administered dissolved in a mixture of ethanol/propylene glycol/saline, the ID50 was 0.83 mg/kg, and when suspended in an ethanol/carboxymethylcellulose vehicle, it was 0.7 mg/kg. It was concluded: 1) that L-365,260 does not produce discriminative stimuli similar to either diazepam or morphine; 2) that the potentiation of morphine-induced behaviour by L-365,260 does not extend to the discriminative stimulus properties of morphine; 3) that L-365,260 itself does not produce readily discriminable interoceptive stimuli in rats; and 4) that L-365,260 does not substitute for the reinforcing drug cocaine.
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Affiliation(s)
- A Jackson
- Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex, UK
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Kemp J, Priestley T, Marshall G, Foster A, Donald A, Singh L, Hutson P, Iversen L, Iversen S, Oles R, Thorn L, Tricklebank M, Vass C. Determination off the potencies of the R-(+) and S-(−) enantiomers off HA-966 as antagonists of the glycine site on the NMDA receptor complex. Eur J Pharmacol 1990. [DOI: 10.1016/0014-2999(90)91962-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Leung TK, Lai JC, Tricklebank M, Davison AN, Lim L. Chronic manganese treatment of rats alters synaptosomal uptake of dopamine and the behavioural response to amphetamine administration. J Neurochem 1982; 39:1496-9. [PMID: 7119805 DOI: 10.1111/j.1471-4159.1982.tb12599.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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