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Dos Santos Barbosa LA, Dutra RC, Moreira ELG, de Carvalho CR. β-caryophyllene, a cannabinoid receptor 2 agonist, decreases the motivational salience and conditioning place preference for palatable food in female mice. Addict Biol 2023; 28:e13249. [PMID: 36577722 DOI: 10.1111/adb.13249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 09/13/2022] [Accepted: 10/13/2022] [Indexed: 11/21/2022]
Abstract
β-caryophyllene (BCP) is a cannabinoid receptor CB2 agonist plant-derived terpenoid found in different essential oil plants, including rosemary, black pepper, copaiba and cannabis. It has GRAS (generally recognized as safe) status and is approved by the FDA (Food and Drug Administration) for food use. BCP displays agonist activity on the CB2 receptor and is a potential therapeutic target in several neuropsychiatric disorders, including anxiety and drug addiction. Unlike CB1 receptors, activation of the CB2 receptors is devoid of psychotomimetic and addictive properties. In this regard, this study aimed to evaluate the effects of BCP on incentive salience ("wanting") performance and motivational properties elicited by sweetened palatable foods in female Swiss mice. After 9 days of training for incentive salience performance for a sweet reward (hazelnut cream with chocolate), food-restricted mice received a systemic injection of BCP (50 and 100 mg/kg) before testing over 3 days. Moreover, independent groups of female mice were tested on sweet reward-induced conditioned place preference (CPP) for 22 consecutive days. To evaluate BCP effects on the expression of seeking behaviour for sweetened food, mice received a single intraperitoneal injection of BCP (50 mg/kg) 30 min before testing on the CPP task. BCP significantly decreased the incentive performance for a sweet reward compared with the control group in a CB2 receptor-dependent manner. Also, BCP suppressed the expression of sweet reward-CPP. Altogether, these preclinical data demonstrate the potential role of BCP in treating disorders associated with food addiction-like behaviour.
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Affiliation(s)
| | - Rafael Cypriano Dutra
- Programa de Pós-Graduação em Neurociências, Universidade Federal de Santa Catarina (UFSC), Florianópolis, Brazil.,Laboratório de Autoimunidade e Imunofarmacologia (LAIF), Departamento de Ciências da Saúde, Campus Araranguá, Universidade Federal de Santa Catarina, Araranguá, Brazil
| | - Eduardo Luiz Gasnhar Moreira
- Programa de Pós-Graduação em Neurociências, Universidade Federal de Santa Catarina (UFSC), Florianópolis, Brazil.,Departamento de Ciências Fisiológicas, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Cristiane Ribeiro de Carvalho
- Programa de Pós-Graduação em Neurociências, Universidade Federal de Santa Catarina (UFSC), Florianópolis, Brazil.,Departamento de Patologia, Universidade Federal de Santa Catarina, Florianópolis, Brazil
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2
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Chronic amphetamine enhances visual input to and suppresses visual output from the superior colliculus in withdrawal. Neuropharmacology 2018; 138:118-129. [DOI: 10.1016/j.neuropharm.2018.05.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 05/01/2018] [Accepted: 05/30/2018] [Indexed: 11/23/2022]
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3
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Turner AC, Stramek A, Kraev I, Stewart MG, Overton PG, Dommett EJ. Chronic amphetamine treatment affects collicular-dependent behaviour. Behav Brain Res 2018; 343:1-7. [PMID: 29407411 DOI: 10.1016/j.bbr.2018.01.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 01/10/2018] [Accepted: 01/22/2018] [Indexed: 12/26/2022]
Abstract
Distractibility can be defined as an attention deficit where orientation toward irrelevant targets cannot be inhibited. There is now mounting evidence that the superior colliculus is a key neural correlate of distractibility, with increased collicular-activity resulting in heightened distractibility. Heightened distractibility is reduced by amphetamine, which acutely suppresses collicular responsiveness. However, when amphetamine is used to treat distractibility, it is given chronically, yet no data exist on whether chronic amphetamine treatment affects the colliculus. Here, the effect of chronic amphetamine treatment was assessed in healthy hooded lister rats on two collicular dependent behaviours following a twenty-eight day treatment period: i) orienting to visual stimuli, and ii) height-dependent modulation of air-righting. We found no significant impact of amphetamine treatment on visual orienting despite showing dose-dependent decreases in orienting to repeated stimuli. However, we did find that treatment with amphetamine significantly reduced the ability to modulate righting according to the height the animal is dropped from - a function known to be dependent on the colliculus. We suggest that the results are in line with previous research showing acute amphetamine suppresses collicular activity and we speculate that the psychostimulant may increase receptive field size, altering time-to-impact calculations carried out by the colliculus during air-righting.
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Affiliation(s)
- Amy C Turner
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, MK7 6AA, UK
| | - Agata Stramek
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, MK7 6AA, UK
| | - Igor Kraev
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, MK7 6AA, UK
| | - Michael G Stewart
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, MK7 6AA, UK
| | - Paul G Overton
- Department of Psychology, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Eleanor J Dommett
- School of Life, Health and Chemical Sciences, The Open University, Milton Keynes, MK7 6AA, UK; Department of Psychology, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, SE5 8AF, UK.
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4
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Brace LR, Kraev I, Rostron CL, Stewart MG, Overton PG, Dommett EJ. Auditory responses in a rodent model of Attention Deficit Hyperactivity Disorder. Brain Res 2015; 1629:10-25. [PMID: 26453290 DOI: 10.1016/j.brainres.2015.09.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 09/28/2015] [Accepted: 09/29/2015] [Indexed: 01/30/2023]
Abstract
A central component of Attention Deficit Hyperactivity Disorder (ADHD) is increased distractibility in response to visual and auditory stimuli, which is linked to the superior colliculus (SC). Furthermore, there is now mounting evidence of altered collicular functioning in ADHD and it is proposed that a hyper-responsive SC could mediate symptoms of ADHD, including distractibility. In the present study we conducted a systematic characterisation of the intermediate and deep layers of the SC in the most commonly used and well-validated model of ADHD, the spontaneously hypertensive rat (SHR), building on prior work showing increased distractible behaviour in this strain using visual distractors. We examined collicular-dependent orienting behaviour, local field potential (LFP) and multiunit activity (MUA) in response to auditory stimuli in the anaesthetised rat, and morphological measures, in the SHR in comparison to the Wistar Kyoto (WKY) and Wistar (WIS). We found no evidence of increased distractibility in the behavioural data but suggest that this may arise due to cochlear hearing loss in the SHR. Furthermore, the electrophysiology data indicate that the SC in the SHR may still be hyper-responsive, normalising the amplitude of auditory responses that would otherwise be reduced due to the hearing impairment. The morphological measures of collicular volume, cell density and ratios did not indicate this potential hyper-responsiveness had a basis at the structural level examined. These findings have implications for future use of the SHR in auditory processing studies and may represent a limitation to the validity of this animal model.
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Affiliation(s)
- Louise R Brace
- Department of Life, Health and Chemical Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - Igor Kraev
- Department of Life, Health and Chemical Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - Claire L Rostron
- Department of Life, Health and Chemical Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - Michael G Stewart
- Department of Life, Health and Chemical Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - Paul G Overton
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Eleanor J Dommett
- Department of Life, Health and Chemical Sciences, The Open University, Milton Keynes MK7 6AA, UK; Department of Psychology, Institute of Psychiatry, Psychology and Neuroscience, King׳s College London, London SE1 3QD, UK.
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5
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Altered visual processing in a rodent model of Attention-Deficit Hyperactivity Disorder. Neuroscience 2015; 303:364-77. [DOI: 10.1016/j.neuroscience.2015.07.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 06/18/2015] [Accepted: 07/01/2015] [Indexed: 11/23/2022]
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Hazan L, Gaisler-Salomon I. Glutaminase1 heterozygous mice show enhanced trace fear conditioning and Arc/Arg3.1 expression in hippocampus and cingulate cortex. Eur Neuropsychopharmacol 2014; 24:1916-24. [PMID: 25453483 DOI: 10.1016/j.euroneuro.2014.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 07/22/2014] [Accepted: 10/11/2014] [Indexed: 01/27/2023]
Abstract
Mice heterozygous for a mutation in the glutaminase (GLS1) gene (GLS1 HZ mice), with reduced glutamate recycling and release, display reduced hippocampal function as well as memory of contextual cues in a delay fear conditioning (FC) paradigm. Here, we asked whether this deficit reflects an inability to process contextual information or a selective alteration in salience attribution. In addition, we asked whether baseline and activity-induced hippocampal activity were diminished in GLS1 HZ mice. For this purpose, we manipulated the relative salience of the conditioned stimulus (CS) and contextual cues in FC tasks, and examined gene expression of the immediate early gene Arc (Arc/Arg3.1) in hippocampus and anterior cingulate cortex (ACC) following trace FC (tFC). The results indicate that GLS1 HZ mice succeed in processing contextual information when the salient CS is absent or less predictive. In addition, in the hippocampus-dependent tFC paradigm GLS1 HZ mice display enhanced CS learning. Furthermore, while baseline arc activation was reduced in GLS1 HZ mice in the hippocampus, in line with previous fMRI findings, it was enhanced in the hippocampus and anterior cingulate cortex following tFC. These findings suggest that GLS1 HZ mice have a pro-cognitive profile in the tFC paradigm, and this phenotype involves activation of both hippocampus and ACC. Taken together with previous work on the GLS1 HZ mouse, this study sheds light on the importance of glutamate transmission to memory processes that require the allocation of attentional resources, and extends our understanding of the underpinnings of attention deficits in SZ.
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Affiliation(s)
- Liran Hazan
- Department of Psychology, University of Haifa, Haifa 3498838, Israel
| | - Inna Gaisler-Salomon
- Department of Psychology, University of Haifa, Haifa 3498838, Israel; Department of Psychiatry, Columbia University, New York, NY 10032, USA.
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7
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Clements KM, Devonshire IM, Reynolds JNJ, Overton PG. Enhanced visual responses in the superior colliculus in an animal model of attention-deficit hyperactivity disorder and their suppression by D-amphetamine. Neuroscience 2014; 274:289-98. [PMID: 24905438 DOI: 10.1016/j.neuroscience.2014.05.054] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 05/27/2014] [Accepted: 05/27/2014] [Indexed: 11/20/2022]
Abstract
Attention-deficit hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder characterized by overactivity, impulsiveness and attentional problems, including an increase in distractibility. A structure that is intimately linked with distractibility is the superior colliculus (SC), a midbrain sensory structure which plays a particular role in the production of eye and head movements. Although others have proposed the involvement of such diverse elements as the frontal cortex and forebrain noradrenaline in ADHD, given the role of the colliculus in distractibility and the increased distractibility in ADHD, we have proposed that distractibility in ADHD arises due to collicular sensory hyper-responsiveness. To further investigate this possibility, we recorded the extracellular activity (multi-unit (MUA) and local field potential (LFP)) in the superficial visual layers of the SC in an animal model of ADHD, the New Zealand genetically hypertensive (GH) rat, in response to wholefield light flashes. The MUA and LFP peak amplitude and summed activity within a one-second time window post-stimulus were both significantly greater in GH rats than in Wistar controls, across the full range of stimulus intensities. Given that baseline firing rate did not differ between the strains, this suggests that the signal-to-noise ratio is elevated in GH animals. D-Amphetamine reduced the peak amplitude and summed activity of the multi-unit response in Wistar animals. It also reduced the peak amplitude and summed activity of the multi-unit response in GH animals, at higher doses bringing it down to levels that were equivalent to those of Wistar animals at baseline. The present results provide convergent evidence that a collicular dysfunction (sensory hyper-responsiveness) is present in ADHD, and that it may underlie the enhanced distractibility. In addition, D-amphetamine - a widely used treatment in ADHD - may have one of its loci of therapeutic action at the level of the colliculus.
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Affiliation(s)
- K M Clements
- Brain Health Research Centre, Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - I M Devonshire
- Laboratory of Developmental Nociception, Nottingham University Medical School, School of Life Sciences, Nottingham NG7 2UH, UK
| | - J N J Reynolds
- Brain Health Research Centre, Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - P G Overton
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
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8
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Yang P, Cai G, Cai Y, Fei J, Liu G. Gamma aminobutyric acid transporter subtype 1 gene knockout mice: a new model for attention deficit/hyperactivity disorder. Acta Biochim Biophys Sin (Shanghai) 2013; 45:578-85. [PMID: 23656791 DOI: 10.1093/abbs/gmt043] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Attention deficit/hyperactivity disorder (ADHD) is characterized by hyperactivity, impaired sustained attention, impulsivity, and is usually accompanied by varying degrees of learning difficulties and lack of motor coordination. However, the pathophysiology and etiology of ADHD remain inconclusive so far. Our previous studies have demonstrated that the gamma aminobutyric acid transporter subtype 1 (GAT1) gene knockout (ko) mouse (gat1-/-) is hyperactive and exhibited impaired memory performance in the Morris water maze. In the current study, we found that the gat1-/- mice showed low levels of attentional focusing and increased impulsivity. In addition, the gat1-/- mice displayed ataxia characterized by defects in motor coordination and balance skills. The hyperactivity in the ko mice was reduced by both methylphenidate and amphetamine. Collectively, these results suggest that GAT1 ko mouse is a new animal model for ADHD studying and GAT1 may be a new target to treat ADHD.
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Affiliation(s)
- Ping Yang
- School of Life Sciences and Technology, TongJi University, Shanghai 200092, China
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9
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Abstract
Impulsive action, the failure to withhold an inappropriate response, is treated clinically with dopamine agonists such as amphetamine. Despite the therapeutic efficacy, these drugs have inconsistent effects on impulsive action in rodents, causing improvements or disruptions in different tasks. Thus, we hypothesized that amphetamine is producing an effect by altering distinct cognitive processes in each task. To test this idea, we used the response inhibition (RI) task and trained rats to withhold responding for sucrose until a signal is presented. We then varied the duration that subjects were required to inhibit responding (short=4 s; long=60 s; or variable=1-60 s) and examined whether this influenced the pattern of premature responses. We also tested the effects of amphetamine (0.0, 0.125, 0.25, 0.5, and 1.0 mg/kg) on each task variant. The probability of premature responding varied across the premature interval with a unique pattern of time-dependent errors emerging in each condition. Amphetamine also had distinct effects on each version: the drug promoted premature responding when subjects expected a consistent delay, regardless of its duration, but reduced premature responding when the delay was unpredictable. We propose that the ability to inhibit a motor response is controlled by a different combination of cognitive processes in the three task conditions. These include timing, conditioned avoidance, and attention, which then interact with amphetamine to increase or decrease impulsive action. The effect of amphetamine on impulsive action, therefore, is not universal, but depends on the subject's experience and expectation of the task demands.
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10
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Dommett EJ, Overton PG, Greenfield SA. Drug therapies for attentional disorders alter the signal-to-noise ratio in the superior colliculus. Neuroscience 2009; 164:1369-76. [PMID: 19747530 DOI: 10.1016/j.neuroscience.2009.09.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Revised: 08/27/2009] [Accepted: 09/03/2009] [Indexed: 10/20/2022]
Abstract
Despite high levels of use, the mechanism of action of effective pharmacotherapies in attention deficit hyperactivity disorder (ADHD) is unknown. It has recently been hypothesized that one site of therapeutic action is the midbrain superior colliculus, a structure traditionally associated with visual processing, but also strongly implicated in distractibility, a core symptom of ADHD. We used male juvenile Wistar rats to examine the effects of therapeutically relevant doses of methylphenidate and d-amphetamine on collicular activity in vitro. Here we report a novel shared mechanism of the two drugs whereby they enhance the signal-to-noise ratio in the superior colliculus. The effects on the signal-to-noise ratio were mediated by serotonin (5-HT) via a pre-synaptic mechanism. This modulatory action would bias the system towards salient events and lead to an overall decrease in distractibility.
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Affiliation(s)
- E J Dommett
- Department of Life Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK.
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11
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Kelly MP, Logue SF, Dwyer JM, Beyer CE, Majchrowski H, Cai Z, Liu Z, Adedoyin A, Rosenzweig-Lipson S, Comery TA. The supra-additive hyperactivity caused by an amphetamine-chlordiazepoxide mixture exhibits an inverted-U dose response: negative implications for the use of a model in screening for mood stabilizers. Pharmacol Biochem Behav 2009; 92:649-54. [PMID: 19303035 DOI: 10.1016/j.pbb.2009.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 02/24/2009] [Accepted: 03/11/2009] [Indexed: 11/25/2022]
Abstract
One of the few preclinical models used to identify mood stabilizers is an assay in which amphetamine-induced hyperactivity (AMPH) is potentiated by the benzodiazepine chlordiazepoxide (CDP), an effect purportedly blocked by mood stabilizers. Our data here challenge this standard interpretation of the AMPH-CDP model. We show that the potentiating effects of AMPH-CDP are not explained by a pharmacokinetic interaction as both drugs have similar brain and plasma exposures whether administered alone or in combination. Of concern, however, we find that combining CDP (1-12 mg/kg) with AMPH (3 mg/kg) results in an inverted-U dose response in outbred CD-1 as well as inbred C57Bl/6N and 129S6 mice (peak hyperactivity at 3 mg/kg CDP+3 mg/kg AMPH). Such an inverted-U dose response complicates interpreting whether a reduction in hyperactivity produced by a mood stabilizer reflects a "blockade" or a "potentiation" of the mixture. In fact, we show that the prototypical mood stabilizer valproic acid augments the effects of CDP on hypolocomotion and anxiolytic-like behavior (increases punished crossings by Swiss-Webster mice in the four-plate test). We argue that these data, in addition to other practical and theoretical concerns surrounding the model, limit the utility of the AMPH-CDP mixture model in drug discovery.
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Affiliation(s)
- Michele P Kelly
- Department of Neuroscience, Discovery Research, Wyeth, Princeton, NJ 08852, USA.
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12
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Gowan JD, Coizet V, Devonshire IM, Overton PG. d-Amphetamine depresses visual responses in the rat superior colliculus: a possible mechanism for amphetamine-induced decreases in distractibility. J Neural Transm (Vienna) 2008; 115:377-87. [DOI: 10.1007/s00702-007-0858-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Accepted: 11/01/2007] [Indexed: 12/22/2022]
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Andretic R, van Swinderen B, Greenspan RJ. Dopaminergic modulation of arousal in Drosophila. Curr Biol 2005; 15:1165-75. [PMID: 16005288 DOI: 10.1016/j.cub.2005.05.025] [Citation(s) in RCA: 260] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2005] [Revised: 05/06/2005] [Accepted: 05/09/2005] [Indexed: 11/17/2022]
Abstract
BACKGROUND Arousal levels in the brain set thresholds for behavior, from simple to complex. The mechanistic underpinnings of the various phenomena comprising arousal, however, are still poorly understood. Drosophila behaviors have been studied that span different levels of arousal, from sleep to visual perception to psychostimulant responses. RESULTS We have investigated neurobiological mechanisms of arousal in the Drosophila brain by a combined behavioral, genetic, pharmacological, and electrophysiological approach. Administration of methamphetamine (METH) suppresses sleep and promotes active wakefulness, whereas an inhibitor of dopamine synthesis promotes sleep. METH affects courtship behavior by increasing sexual arousal while decreasing successful sexual performance. Electrophysiological recordings from the medial protocerebrum of wild-type flies showed that METH ingestion has rapid and detrimental effects on a brain response associated with perception of visual stimuli. Recordings in genetically manipulated animals show that dopaminergic transmission is required for these responses and that visual-processing deficits caused by attenuated dopaminergic transmission can be rescued by METH. CONCLUSIONS We show that changes in dopamine levels differentially affect arousal for behaviors of varying complexity. Complex behaviors, such as visual perception, degenerate when dopamine levels are either too high or too low, in accordance with the inverted-U hypothesis of dopamine action in the mammalian brain. Simpler behaviors, such as sleep and locomotion, show graded responses that follow changes in dopamine level.
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Affiliation(s)
- Rozi Andretic
- The Neuroscience Institute, San Diego, California 92121, USA
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14
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Brown RW, Bardo MT, Mace DD, Phillips SB, Kraemer PJ. D-amphetamine facilitation of morris water task performance is blocked by eticlopride and correlated with increased dopamine synthesis in the prefrontal cortex. Behav Brain Res 2000; 114:135-43. [PMID: 10996054 DOI: 10.1016/s0166-4328(00)00225-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of posttraining D-amphetamine on Morris water task (MWT) performance was analyzed in this study by training rats using a single training trial per day procedure. In addition to acquisition latency, learning was assessed by a probe trial given 24 h after the last training trial. Rats given immediate post-trial D-amphetamine demonstrated improved performance over saline rats on both acquisition and the probe trial. An analysis of the mechanisms underlying facilitation revealed that eticlopride (a D2 antagonist) blocked D-amphetamine's facilitatory effects on the probe trial and dopamine synthesis was increased in the medial prefrontal cortex in the D-amphetamine group relative to controls. These results show that chronic administration of posttraining D-amphetamine facilitated MWT performance, and this facilitation may be mediated by the dopaminergic system and dopamine synthesis in the prefrontal cortex.
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Affiliation(s)
- R W Brown
- Department of Psychology and Neuroscience, University of Lethbridge, 4401 University Drive, T1K 3M4, Lethbridge, AB, Canada.
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Belzung C, Leguisquet AM, Barreau S, Delion-Vancassel S, Chalon S, Durand G. Alpha-linolenic acid deficiency modifies distractibility but not anxiety and locomotion in rats during aging. J Nutr 1998; 128:1537-42. [PMID: 9732316 DOI: 10.1093/jn/128.9.1537] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In rodents, chronic dietary alpha-linolenic acid deficiency decreases learning and memory and alters dopaminergic and serotoninergic neurotransmission. However, these two neurotransmitter systems are related mainly to attention, emotion and locomotion. Therefore, we decided to investigate the effects of dietary alpha-linolenic acid deficiency in rats tested with animal models of distractibility (the distractometer procedure), anxiety (the elevated plus maze) and ambulatory activity (a circular corridor). Moreover, because these neurochemical modifications persist during aging, we decided to study the effects of aging on these behaviors by using rats aged 2, 6, 12 and 24 mo. An age-related decline in distractibility was observed that was accelerated by linolenic acid deficiency. Indeed, an age-related reduction in distractibility was found in so far as distraction time was reduced at the age of 12 mo in controls and at the age of 24 mo in deficient groups compared with 2-mo-old rats. Moreover, distraction time was significantly lower in 6- and 24-mo-old rats fed a deficient diet compared with age-matched controls. Anxiety was not modified by diet or age. Finally, a parallel decrease in locomotion was exhibited by rats fed both diets between 6 and 12 mo of age. Locomotion was not modified by diet. These results show that dietary alpha-linolenic deficiency alters behavior in a very specific way; distractibility is modified by diet, whereas anxiety and locomotion are not, suggesting that particular brain areas may be altered.
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Affiliation(s)
- C Belzung
- Laboratoire d'Ethologie et de Pharmacologie du Comportement, F-37200 Tours, France
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16
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Agmo A, Medrano A, Garrido N, Alonso P. GABAergic drugs inhibit amphetamine-induced distractibility in the rat. Pharmacol Biochem Behav 1997; 58:119-26. [PMID: 9264079 DOI: 10.1016/s0091-3057(96)00380-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Drugs facilitating GABAergic neurotransmission have been reported to block some behavioral actions of dopaminergic stimulation but not others. The present experiments were performed with the purpose to extend the range of behaviors in which the interaction between GABA and dopamine have been studied. The ability of the GABAB agonist baclofen and the GABA transaminase inhibitor sodium valproate to block the enhanced distractibility produced by amphetamine was evaluated in a procedure especially designed for analyzing drugs' effects on distractibility. Briefly, rats were trained to traverse a straight runway with a sucrose solution as reinforcement. Once the response had been acquired, an additional runway ending in an empty box was connected. The time spent investigating this additional runway is the measure of distractibility. Male rats treated with amphetamine, 1 mg/kg, displayed an increase of the time spent in the additional runway. Baclofen, 2.5 and 5 mg/kg, and sodium valproate, 100 and 200 mg/kg, had no effect on distraction behavior when administered alone. However, when these drugs were administered together with amphetamine, 1 mg/kg, they completely inhibited the effects of the stimulant on distractibility. These data show that distractibility is similar to discrimination learning with regard to the capacity of GABAergic drugs to block the effects of dopaminergic stimulation. It is different from locomotor activity, however, where GABAergic drugs are ineffective in this respect.
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Affiliation(s)
- A Agmo
- Escuela de Psicología, Universidad Anáhuac, Mexico City, Mexico.
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