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Aringhieri S, Carli M, Kolachalam S, Verdesca V, Cini E, Rossi M, McCormick PJ, Corsini GU, Maggio R, Scarselli M. Molecular targets of atypical antipsychotics: From mechanism of action to clinical differences. Pharmacol Ther 2018; 192:20-41. [PMID: 29953902 DOI: 10.1016/j.pharmthera.2018.06.012] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The introduction of atypical antipsychotics (AAPs) since the discovery of its prototypical drug clozapine has been a revolutionary pharmacological step for treating psychotic patients as these allow a significant recovery not only in terms of hospitalization and reduction in symptoms severity, but also in terms of safety, socialization and better rehabilitation in the society. Regarding the mechanism of action, AAPs are weak D2 receptor antagonists and they act beyond D2 antagonism, involving other receptor targets which regulate dopamine and other neurotransmitters. Consequently, AAPs present a significant reduction of deleterious side effects like parkinsonism, hyperprolactinemia, apathy and anhedonia, which are all linked to the strong blockade of D2 receptors. This review revisits previous and current findings within the class of AAPs and highlights the differences in terms of receptor properties and clinical activities among them. Furthermore, we propose a continuum spectrum of "atypia" that begins with risperidone (the least atypical) to clozapine (the most atypical), while all the other AAPs fall within the extremes of this spectrum. Clozapine is still considered the gold standard in refractory schizophrenia and in psychoses present in Parkinson's disease, though it has been associated with adverse effects like agranulocytosis (0.7%) and weight gain, pushing the scientific community to find new drugs as effective as clozapine, but devoid of its side effects. To achieve this, it is therefore imperative to characterize and compare in depth the very complex molecular profile of AAPs. We also introduce relatively new concepts like biased agonism, receptor dimerization and neurogenesis to identify better the old and new hallmarks of "atypia". Finally, a detailed confrontation of clinical differences among the AAPs is presented, especially in relation to their molecular targets, and new means like therapeutic drug monitoring are also proposed to improve the effectiveness of AAPs in clinical practice.
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Affiliation(s)
- Stefano Aringhieri
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Marco Carli
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Shivakumar Kolachalam
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Valeria Verdesca
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Enrico Cini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Mario Rossi
- Institute of Molecular Cell and Systems Biology, University of Glasgow, UK
| | - Peter J McCormick
- William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London EC1M 6BQ, UK
| | - Giovanni U Corsini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy
| | - Roberto Maggio
- Biotechnological and Applied Clinical Sciences Department, University of L'Aquila, Italy
| | - Marco Scarselli
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Italy.
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Servonnet A, Minogianis EA, Bouchard C, Bédard AM, Lévesque D, Rompré PP, Samaha AN. Neurotensin in the nucleus accumbens reverses dopamine supersensitivity evoked by antipsychotic treatment. Neuropharmacology 2017; 123:10-21. [DOI: 10.1016/j.neuropharm.2017.05.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 05/09/2017] [Accepted: 05/13/2017] [Indexed: 12/20/2022]
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Bhattacharjee AK, Chang L, Chen M, White L, Bell JM, Bazinet RP, Rapoport SI. Chronic d-amphetamine depresses an imaging marker of arachidonic acid metabolism in rat brain. Int J Neuropsychopharmacol 2008; 11:957-69. [PMID: 18570702 PMCID: PMC2676692 DOI: 10.1017/s1461145708008833] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acute d-amphetamine (d-Amph) administration to rats leads to the release of arachidonic acid (AA, 20:4n-6) as a second messenger following indirect agonism at dopamine D2-like receptors in the brain. We hypothesized that chronically administered d-Amph in rats also would alter brain AA metabolism and signalling. To test this, adult male rats were injected i.p. daily for 2 wk with saline or 2.5 mg/kg d-Amph. After a 1-d washout, the unanaesthetized rats were injected acutely with i.v. saline, 1 mg/kg quinpirole (a D2-like receptor agonist) or 5.0 mg/kg SKF-38393 (a D1-like receptor agonist), followed by i.v. [1-14C]AA. The AA incorporation coefficient k* (brain radioactivity/integrated plasma radioactivity), a marker of AA signalling and metabolism, was quantified using autoradiography in each of 62 brain regions. Compared with chronic saline, chronic d-Amph widely decreased baseline values of k* in brain regions having D2-like receptors. On the other hand, chronic amphetamine did not alter the k* responses to quinpirole seen in chronic saline-treated rats. SKF-38393 had minimal effects on k* in both chronic saline-treated and amphetamine-treated rats, consistent with D1-like receptors not being coupled to AA signalling. The ability of chronic d-Amph after 1-d washout to down-regulate baseline values of k* probably reflects neuroplastic changes in brain AA signalling, and may correspond to depressive behaviours noted following withdrawal from chronic amphetamine in humans and in rats.
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MESH Headings
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/pharmacology
- Animals
- Arachidonic Acid/metabolism
- Arachidonic Acid/pharmacokinetics
- Autoradiography
- Biomarkers/analysis
- Biomarkers/metabolism
- Brain Chemistry/drug effects
- Central Nervous System Stimulants/administration & dosage
- Central Nervous System Stimulants/pharmacology
- Depression, Chemical
- Dextroamphetamine/administration & dosage
- Dextroamphetamine/pharmacology
- Dopamine Agonists/pharmacology
- Fatty Acids, Nonesterified/blood
- Half-Life
- Image Processing, Computer-Assisted
- Injections, Intraperitoneal
- Male
- Quinpirole/pharmacology
- Rats
- Rats, Inbred F344
- Receptors, Dopamine D2/agonists
- Receptors, Phospholipase A2/drug effects
- Signal Transduction/drug effects
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Affiliation(s)
- Abesh K Bhattacharjee
- Brain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health, Bethesda, MD, USA.
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4
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Less is more: antipsychotic drug effects are greater with transient rather than continuous delivery. Biol Psychiatry 2008; 64:145-52. [PMID: 18295747 DOI: 10.1016/j.biopsych.2008.01.010] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Revised: 12/13/2007] [Accepted: 01/18/2008] [Indexed: 11/24/2022]
Abstract
BACKGROUND Most studies on the effects of antipsychotics focus on achieving threshold levels of the drug. The speed and frequency with which drug concentrations reach threshold levels and rise and fall within the day are generally ignored. Based on prior data, we predicted that variations in the within-day kinetics of antipsychotic drug delivery would produce different outcomes, even if we held achieved dose, route, and total duration of treatment constant. METHODS We compared the effects of within-day continuous (via minipump) versus transient (via subcutaneous injection) haloperidol treatment (n = 4-9/condition/experiment) at doses that yield equivalent peak levels of striatal D2 receptor occupancy (approximately 74%). RESULTS Over time, transient haloperidol gained efficacy, while continuous haloperidol lost efficacy in two animal models of antipsychotic-like effects (the suppression of amphetamine-induced locomotion and conditioned avoidance responding). This was related to the fact that continuous treatment led to a greater increase in striatal D2 receptor numbers--particularly D2 receptors in a high-affinity state for dopamine--relative to transient treatment and produced behavioral dopamine supersensitivity (as indicated by an enhanced locomotor response to amphetamine following antipsychotic treatment cessation). Treatment kinetics also influenced the postsynaptic response to haloperidol. Transient treatment increased striatal c-fos messenger RNA (mRNA) expression, while continuous treatment did not. CONCLUSIONS Relative to continuous antipsychotic exposure, within-day transient exposure is more efficacious behaviorally and is associated with a distinct molecular and gene expression profile. Thus, differences in the within-day kinetics of antipsychotic treatment can have different efficacy, and the potential clinical implications of this should be explored further.
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5
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van Nimwegen L, de Haan L, van Beveren N, van den Brink W, Linszen D. Adolescence, schizophrenia and drug abuse: a window of vulnerability. Acta Psychiatr Scand Suppl 2005:35-42. [PMID: 15877720 DOI: 10.1111/j.1600-0447.2005.00543.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To discuss the neurobiological and psychosocial developmental factors in adolescence contributing to simultaneous onset and co-occurrence of psychosis and substance use disorders. METHOD A review of the literature. RESULTS Adolescence is a period with specific psychosocial challenges and specific changes in the brain that increase the probability of the onset of both psychosis and substance abuse, in predisposed people. In vulnerable adolescents it is proposed that an excessive pruning of dopaminergic neurones leads to mesocortical hypofrontality causing anhedonia and dysphoria. At the same time, anhedonia and dysphoria are important risk factors for the development of substance abuse. In turn, hypofrontality leads to a reduction in mesocortical feedback inhibition of the mesolimbic system resulting in aberrant salience and positive symptoms. Finally, the development of aberrant salience plays a role in both psychoses and craving. CONCLUSION Attention should be paid to the interaction of drug abuse and schizophrenia and an integrated treatment is needed. Dysphoria and anhedonia in schizophrenic adolescents are important factors in treatment with antipsychotic medication, both in terms of patient satisfaction and in the prevention of substance abuse.
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Affiliation(s)
- L van Nimwegen
- Department of Psychiatry, Academical Medical Center, University of Amsterdam, Amsterdam, Netherlands.
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Kadota T, Kadota K. Neurotoxic morphological changes induced in the medial prefrontal cortex of rats behaviorally sensitized to methamphetamine. ACTA ACUST UNITED AC 2004; 67:241-51. [PMID: 15570889 DOI: 10.1679/aohc.67.241] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The present study examined whether the development in rats of behavioral sensitization to methamphetamine (MAP) is related to the development of neurotoxic morphological changes presumably induced in the medial prefrontal cortex (MFC). Male rats were intraperitonieally injected with MAP (5 mg/kg) once a day for 12 days (day 1-day 12), and then the drug was withdrawn for 7-42 days (WD7-WD42). The MAP- treatment caused hypersensitivity of a successive head-movement stereotypy, which reached a basic plateau level on day 4, and rose successively to a higher level by day 12. Morphological changes were histochemically and morphometrically examined in the MFC. In the strata covering layers II and III, the densities of tyrosine hydroxylase (TH)-immunoreactive axons decreased on a daily basis to 50% of the control on day 4 and then to 40% on days 6 and 12. The densities of dopamine-,beta-hydroxylase (DBH)-immunoreactive axons did not change during the injection period. A few TUNEL-positive cells were observed in a unit area (0.25 mm2) covering layers II-V on day 6 and they increased to 19 and 16 on day 12 and WD7, respectively. These observations demonstrate a role for the neurotoxic changes in the MFC in the processes of behavioral sensitization of a stereotypy to a low dose of MAP.
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Affiliation(s)
- Tomoko Kadota
- Department of Bioenvironmental Medicine and Anatomy, Chiba University Graduate School of Medicine, Chiba, Japan.
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Park YH, Kantor L, Wang KKW, Gnegy ME. Repeated, intermittent treatment with amphetamine induces neurite outgrowth in rat pheochromocytoma cells (PC12 cells). Brain Res 2002; 951:43-52. [PMID: 12231455 DOI: 10.1016/s0006-8993(02)03103-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Repeated, intermittent treatment with amphetamine (AMPH) leads to long-term neurobiological adaptations in rat brain including an increased number and branching of dendritic spines. This effect depends upon several different cell types in the intact brain. Here we demonstrate that repeated, intermittent AMPH treatment induces neurite outgrowth in cultured PC12 cells without the requirement for integrated synaptic pathways. PC12 cells were treated with 1 micro M AMPH for 5 min a day, for 5 days. After 10 days of withdrawal, there was an increase in the percentage of cells with neurites ( approximately 30%) and the length of neurites as well as an increase in the level of GAP-43 and neurofilament-M. Neurite outgrowth was enhanced as withdrawal time was increased. Neurite outgrowth was much greater following repeated, intermittent treatment with AMPH compared to continuous or single treatment with AMPH. Pretreatment with cocaine, a monoamine transporter blocker, inhibited the AMPH-mediated increase in neurite outgrowth. Neither NGF antibody nor DA receptor antagonists blocked AMPH-induced neurite outgrowth, demonstrating that AMPH-induced neurite outgrowth is not dependent on endogenous NGF release or DA receptors. Thus we have demonstrated that repeated, intermittent treatment with AMPH has a neurotrophic effect in PC12 cells. The effect requires the action of AMPH on the norepinephrine transporter, and shares characteristics in its development with other forms of sensitization but does not require an intact neuroanatomy.
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Affiliation(s)
- Yang Hae Park
- Department of Pharmacology, 2220 MSRB III, University of Michigan School of Medicine, 1150 W Medical Center Dr, Ann Arbor, MI 48109-0632, USA
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Vukosavic S, Ruzdijic S, Veskov R, Rakic L, Kanazir S. Differential effects of amphetamine and phencyclidine on the expression of growth-associated protein GAP-43. Neurosci Res 2001; 40:133-40. [PMID: 11377751 DOI: 10.1016/s0168-0102(01)00222-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The purpose of the present study was to test changes in the expression of growth-associated protein (GAP-43) after chronic treatment with two different psychotomimetic drugs: amphetamine and phencyclidine. Rats were treated chronically for 7 days (twice daily) with 5 mg/kg of amphetamine and phencyclidine and sacrificed after 2, 5 or 7 days of treatment, and following 7, 14 or 21 days of recovery after full treatment (7 days). Separate groups of rats were treated on the same regiment with haloperidol, and control group was treated with vehicle. To determine the effects of different psychotomimetic drugs on the expression of GAP-43 we have used Northern blotting and quantitative in situ hybridization. Treatment with amphetamine induced decrease of GAP-43 mRNA expression, that was detected also during recovery period, up to 14 days after the last day of 7 days treatments. On the contrary, PCP induced increase of GAP-43 mRNA expression, that was detectable from the first days of treatment until 21 days after the last day of treatment. Treatment with haloperidol did not produce significant changes in GAP-43 mRNA expression. It can be suggested that GAP-43 upregulation upon phencyclidine treatment occurs as a result of functional activation of pathways able to participate in remodeling, while amphetamine showed neurotoxic effect, decreasing expression of GAP-43 mRNA.
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Affiliation(s)
- S Vukosavic
- Institute for Biological Research, 29 Novembar 142, Belgrade, Yugoslavia.
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9
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Ginovart N, Farde L, Halldin C, Swahn CG. Changes in striatal D2-receptor density following chronic treatment with amphetamine as assessed with PET in nonhuman primates. Synapse 1999; 31:154-62. [PMID: 10024013 DOI: 10.1002/(sici)1098-2396(199902)31:2<154::aid-syn9>3.0.co;2-k] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent brain imaging studies suggest that schizophrenia may be related to abnormally high amphetamine-induced dopamine release. It is known that repeated use of amphetamine may cause paranoid psychosis and persisting stereotypies. The biochemical background for these signs and symptoms has not been clarified. In this study, positron emission tomography and [11C]raclopride were used to determine central D2-dopamine receptor density (Bmax) and apparent affinity (K(D)app) in Cynomolgus monkeys before and after 14 days of treatment with d-amphetamine sulphate (2 mg/kg/day; s.c.). One day after withdrawal from amphetamine, K(D)app was increased, suggesting [11C]raclopride competition with elevated concentration of dopamine. At 7 and 14 days after withdrawal, there was a 19-26% decrease in Bmax but no change in K(D)app as compared to baseline. Although this study was performed on two monkeys only, there was thus no support for the view that chronic intermittent hyperactivity of the dopamine system may be related to an upregulation of striatal D2-dopamine receptors. Repeated administration of amphetamine may, rather, cause a long-lasting downregulation of the D2-receptor density, which may be a neurochemical correlate to the abnormal movements, anhedonia, anxiety, and depression seen in psychostimulant abusers.
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Affiliation(s)
- N Ginovart
- Karolinska Institutet, Department of Clinical Neuroscience, Karolinska Hospital, Stockholm, Sweden.
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Willis GL, Armstrong SM. Orphan neurones and amine excess: the functional neuropathology of Parkinsonism and neuropsychiatric disease. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1998; 27:177-242. [PMID: 9729369 DOI: 10.1016/s0165-0173(98)00013-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The aetiology and treatment of Parkinsonism is currently conceptualised within a dopamine (DA) deficiency-repletion framework. Loss of striatal DA is thought to cause motor impairment of which tremor, bradykinaesia and rigidity are prominent features. Repletion of deficient DA should at least minimise parkinsonian signs and symptoms. In Section 2, based on extensive pre-clinical and clinical findings, the instability of this approach to Parkinsonism is scrutinised as the existing negative findings challenging the DA deficiency hypothesis are reviewed and reinterpreted. In Section 3 it is suggested that Parkinsonism is due to a DA excess far from the striatum in the area of the posterior lateral hypothalamus (PLH) and the substantia nigra (SN). This unique area, around the diencephalon/mesencephalon border (DCMCB), is packed with many ascending and descending fibres which undergo functional transformation during degeneration, collectively labelled 'orphan neurones'. These malformed cells remain functional resulting in pathological release of transmitter and perpetual neurotoxicity. Orphan neurone formation is commonly observed in the PLH of animals and in man exhibiting Parkinsonism. The mechanism by which orphan neurones impair motor function is analogous to that seen in the diseased human heart. From this perspective, to conceptualise orphan neurones at the DCMCB as 'Time bombs in the brain' is neither fanciful nor unrealistic [E.M. Stricker, M.J. Zigmond, Comments on effects of nigro-striatal dopamine lesions, Appetite 5 (1984) 266-267] as the DA excess phenomenon demands a different therapeutic approach for the management of Parkinsonism. In Section 4 the focus is on this novel concept of treatment strategies by concentrating on non-invasive, pharmacological and surgical modification of functional orphan neurones as they affect adjacent systems. The Orphan neurone/DA excess hypothesis permits a more comprehensive and defendable interpretation of the interrelationship between Parkinsonism and schizophrenia and other related disorders.
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Affiliation(s)
- G L Willis
- The Bronowski Institute of Behavioural Neuroscience, Coliban Medical Centre, Kyneton, Victoria 3444, Australia
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Del Arco A, Castañeda TR, Mora F. Amphetamine releases GABA in striatum of the freely moving rat: involvement of calcium and high affinity transporter mechanisms. Neuropharmacology 1998; 37:199-205. [PMID: 9680244 DOI: 10.1016/s0028-3908(98)00013-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Using microdialysis the effect was investigated of amphetamine (AMPH) infusions into the striatum on the release of GABA in the freely moving rat. AMPH (5, 10 and 20 microg/microl), infused through a microdialysis probe at the rate of 2.5 microl/min, produced a dose-related increase in extracellular concentrations of GABA. At the highest dose (20 microg/microl), AMPH increased GABA from 0.08 +/- 0.01 to 0.67 +/- 0.14 microM. Increases in extracellular GABA produced by AMPH were both calcium-dependent and high affinity GABA transporter-mediated. A medium free of calcium reduced the increase of extracellular GABA produced by AMPH by 37%. Nipecotic acid (2, 4 and 8 mM), a specific GABA re-uptake blocker, significantly attenuated increases in extracellular GABA, but not GLU, produced by AMPH (20 microg/microl). This study is the first in vivo evidence showing the release of GABA produced by AMPH through a high affinity transporter mechanism.
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Affiliation(s)
- A Del Arco
- Department of Physiology, Faculty of Medicine, Universidad Complutense, Ciudad universitaria, Madrid, Spain
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12
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Kratofil PH, Baberg HT, Dimsdale JE. Self-mutilation and severe self-injurious behavior associated with amphetamine psychosis. Gen Hosp Psychiatry 1996; 18:117-20. [PMID: 8833581 DOI: 10.1016/0163-8343(95)00126-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Amphetamine abuse is widespread and is frequently encountered in general hospital settings. We have recently seen amphetamine-induced transient psychosis associated with severe self-injurious behavior and self-mutilation. In the setting of bizarre and/or severe self-injurious behavior, screening for amphetamines is indicated.
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Affiliation(s)
- P H Kratofil
- Department of Psychiatry, University of California, San Diego, USA
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13
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Stephans SE, Yamamoto BY. Effect of repeated methamphetamine administrations on dopamine and glutamate efflux in rat prefrontal cortex. Brain Res 1995; 700:99-106. [PMID: 8624733 DOI: 10.1016/0006-8993(95)00938-m] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Pretreatment with psychostimulants such as methamphetamine (METH) results in augmented mesostriatal dopamine transmission upon a challenge administration of the drug. This effect can be blocked by dopamine antagonists and excitatory amino acid antagonists. However, no direct comparisons have been made with respect to the effects of a low-dose pretreatment regimen of METH on impulse and transporter-mediated dopamine release or to what extent glutamate release is altered by a pretreatment regimen with METH. The purpose of this study was to examine dopamine and glutamate efflux in the prefrontal cortex and striatum in rats pretreated with METH following either high potassium (80 microM) infusion or after a systemic injection of a low dose of METH. Extracellular dopamine and glutamate concentrations in the prefrontal cortex and striatum were measured in vivo by microdialysis. Potassium infusion increased extracellular dopamine and glutamate concentrations to a greater extent in the prefrontal cortex than in the striatum of METH-pretreated rats compared to saline-pretreated controls. A low dose METH challenge significantly increased extracellular dopamine but not glutamate concentrations in both prefrontal cortex and striatum of all animals. Moreover, the acute METH-induced increased in cortical dopamine efflux was significantly greater in rats pretreated with METH. Overall, these data are the first evidence that repeated METH administrations can enhance cortical glutamate efflux and indicate that a low dose pretreatment regimen of METH enhances dopamine transmission in the prefrontal cortex through both transporter and depolarization-induced mechanisms.
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Affiliation(s)
- S E Stephans
- Department of Psychiatry, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Lillrank SM, Oja SS, Saransaari P. The effect of phencyclidine on [3H]GABA and [3H]flunitrazepam binding in the brain of naive and handling-habituated rats. ACTA PHYSIOLOGICA SCANDINAVICA 1995; 153:33-41. [PMID: 7625166 DOI: 10.1111/j.1748-1716.1995.tb09831.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The effects of handling and handling combined with phencyclidine (PCP) treatment on GABAergic neurotransmission were studied in Sprague-Dawley rats. The animal material consisted of handling-habituated (HH, for 11 d), acutely handled (naive, N), handling-habituated and PCP-treated (10 mg kg-1 i.p., HH + PCP) and acutely handled (naive) PCP-treated (N + PCP) and unhandled 'control' rats. The binding of [3H]GABA and [3H]flunitrazepam (FLU) was studied with membranes and the release of [3H]GABA with slices prepared from the striatum and frontal cortex. In the striatum the maximal binding capacity (Bmax) and the binding constant (KD) of [3H]GABA were the same in N and HH rats, but in the frontal cortex KD was lower in N rats. KD constants of [3H]FLU were significantly lower in both brain areas in N rats than in HH rats. After PCP treatment both Bmax and KD for [3H]FLU increased in these two brain areas in handling-habituated rats, whereas Bmax of [3H]GABA diminished. Neither handling nor PCP had any effect on [3H]GABA release from striatal and frontal cortical slices. Handling prior to killing thus affects differently the GABAergic parameters studied and modulates the PCP-induced effects.
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Affiliation(s)
- S M Lillrank
- Tampere Brain Reserach Center, Department of Biomedical Sciences, University of Tampere, Finland
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