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Perez de la Mora M, Hernandez-Mondragon C, Crespo-Ramirez M, Rejon-Orantes J, Borroto-Escuela DO, Fuxe K. Conventional and Novel Pharmacological Approaches to Treat Dopamine-Related Disorders: Focus on Parkinson's Disease and Schizophrenia. Neuroscience 2019; 439:301-318. [PMID: 31349007 DOI: 10.1016/j.neuroscience.2019.07.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 06/25/2019] [Accepted: 07/12/2019] [Indexed: 12/17/2022]
Abstract
The dopaminergic system integrated by cell groups distributed in several brain regions exerts a modulatory role in brain. Particularly important for this task are the mesencephalic dopamine neurons, which from the substantia nigra and ventral tegmental area project to the dorsal striatum and the cortical/subcortical limbic systems, respectively. Dopamine released from these neurons operates mainly via the short distance extrasynaptic volume transmission and activates five different dopaminergic receptor subtypes modulating synaptic GABA and glutamate transmission. To accomplish this task dopaminergic neurons keep mutual modulating interactions with neurons of other neurotransmitter systems, including allosteric receptor-receptor interactions in heteroreceptor complexes. As a result of its modulatory role dopaminergic mechanisms are involved in either the etiology or physiopathology of many brain diseases such as Parkinsońs disease and schizophrenia. The aim of this work is to review some novel and conventional approaches that either have been used or are currently employed to treat these diseases. Particular attention is paid to the approaches derived from the knowledge recently acquired in the realm of receptor-receptor interactions taking place through multiple dopamine heteroreceptor complexes in the plasma membrane. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.
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Affiliation(s)
- Miguel Perez de la Mora
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico.
| | | | - Minerva Crespo-Ramirez
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - José Rejon-Orantes
- Pharmacobiology Experimental laboratory, Faculty of Medicine, Universidad Autónoma de Chiapas
| | | | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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2
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Seizert CA. The neurobiology of the male sexual refractory period. Neurosci Biobehav Rev 2018; 92:350-377. [DOI: 10.1016/j.neubiorev.2018.06.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 04/03/2018] [Accepted: 06/13/2018] [Indexed: 02/07/2023]
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Abstract
Aripiprazole was the first antipsychotic developed to possess agonist properties at dopamine D2 autoreceptors, a groundbreaking strategy that presented a new vista for schizophrenia drug discovery. The dopamine D2 receptor is the crucial target of all extant antipsychotics, and all developed prior to aripiprazole were D2 receptor antagonists. Extensive blockade of these receptors, however, typically produces extrapyramidal (movement) side effects, which plagued first-generation antipsychotics, such as haloperidol. Second-generation antipsychotics, such as clozapine, with unique polypharmacology and D2 receptor binding kinetics, have significantly lower risk of movement side effects but can cause myriad additional ones, such as severe weight gain and metabolic dysfunction. Aripiprazole's polypharmacology, characterized by its unique agonist activity at dopamine D2 and D3 and serotonin 5-HT1A receptors, as well as antagonist activity at serotonin 5-HT2A receptors, translates to successful reduction of positive, negative, and cognitive symptoms of schizophrenia, while also mitigating risk of weight gain and movement side effects. New observations, however, link aripiprazole to compulsive behaviors in a small group of patients, an unusual side effect for antipsychotics. In this review, we discuss the chemical synthesis, pharmacology, pharmacogenomics, drug metabolism, and adverse events of aripiprazole, and we present a current understanding of aripiprazole's neurotherapeutic mechanisms, as well as the history and importance of aripiprazole to neuroscience.
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Affiliation(s)
- Austen B. Casey
- Department of Pharmaceutical Sciences, Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115, United States
| | - Clinton E. Canal
- Department of Pharmaceutical Sciences, Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115, United States
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Pan B, Lian J, Huang XF, Deng C. Aripiprazole Increases the PKA Signalling and Expression of the GABAA Receptor and CREB1 in the Nucleus Accumbens of Rats. J Mol Neurosci 2016; 59:36-47. [PMID: 26894264 DOI: 10.1007/s12031-016-0730-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 02/10/2016] [Indexed: 12/24/2022]
Abstract
The GABAA receptor is implicated in the pathophysiology of schizophrenia and regulated by PKA signalling. Current antipsychotics bind with D2-like receptors, but not the GABAA receptor. The cAMP-responsive element-binding protein 1 (CREB1) is also associated with PKA signalling and may be related to the positive symptoms of schizophrenia. This study investigated the effects of antipsychotics in modulating D2-mediated PKA signalling and its downstream GABAA receptors and CREB1. Rats were treated orally with aripiprazole (0.75 mg/kg, ter in die (t.i.d.)), bifeprunox (0.8 mg/kg, t.i.d.), haloperidol (0.1 mg/kg, t.i.d.) or vehicle for 1 week. The levels of PKA-Cα and p-PKA in the prefrontal cortex (PFC), nucleus accumbens (NAc) and caudate putamen (CPu) were detected by Western blots. The mRNA levels of Gabrb1, Gabrb2, Gabrb3 and Creb1, and their protein expression were measured by qRT-PCR and Western blots, respectively. Aripiprazole elevated the levels of p-PKA and the ratio of p-PKA/PKA in the NAc, but not the PFC and CPu. Correlated with this elevated PKA signalling, aripiprazole elevated the mRNA and protein expression of the GABAA (β-1) receptor and CREB1 in the NAc. While haloperidol elevated the levels of p-PKA and the ratio of p-PKA/PKA in both NAc and CPu, it only tended to increase the expression of the GABAA (β-1) receptor and CREB1 in the NAc, but not the CPu. Bifeprunox had no effects on PKA signalling in these brain regions. These results suggest that aripiprazole has selective effects on upregulating the GABAA (β-1) receptor and CREB1 in the NAc, probably via activating PKA signalling.
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Affiliation(s)
- Bo Pan
- Antipsychotic Research Laboratory, Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia
- Centre for Translational Neuroscience, School of Medicine, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Jiamei Lian
- Antipsychotic Research Laboratory, Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia
- Centre for Translational Neuroscience, School of Medicine, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Xu-Feng Huang
- Centre for Translational Neuroscience, School of Medicine, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Chao Deng
- Antipsychotic Research Laboratory, Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
- Centre for Translational Neuroscience, School of Medicine, University of Wollongong, Wollongong, NSW, 2522, Australia.
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Aripiprazole and Haloperidol Activate GSK3β-Dependent Signalling Pathway Differentially in Various Brain Regions of Rats. Int J Mol Sci 2016; 17:459. [PMID: 27043526 PMCID: PMC4848915 DOI: 10.3390/ijms17040459] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 03/11/2016] [Accepted: 03/21/2016] [Indexed: 11/27/2022] Open
Abstract
Aripiprazole, a dopamine D2 receptor (D2R) partial agonist, possesses a unique clinical profile. Glycogen synthase kinase 3β (GSK3β)-dependent signalling pathways have been implicated in the pathophysiology of schizophrenia and antipsychotic drug actions. The present study examined whether aripiprazole differentially affects the GSK3β-dependent signalling pathways in the prefrontal cortex (PFC), nucleus accumbens (NAc), and caudate putamen (CPu), in comparison with haloperidol (a D2R antagonist) and bifeprunox (a D2R partial agonist). Rats were orally administrated aripiprazole (0.75 mg/kg), bifeprunox (0.8 mg/kg), haloperidol (0.1 mg/kg) or vehicle three times per day for one week. The levels of protein kinase B (Akt), p-Akt, GSK3β, p-GSK3β, dishevelled (Dvl)-3, and β-catenin were measured by Western Blots. Aripiprazole increased GSK3β phosphorylation in the PFC and NAc, respectively, while haloperidol elevated it in the NAc only. However, Akt activity was not changed by any of these drugs. Additionally, both aripiprazole and haloperidol, but not bifeprunox, increased the expression of Dvl-3 and β-catenin in the NAc. The present study suggests that activation of GSK3β phosphorylation in the PFC and NAc may be involved in the clinical profile of aripiprazole; additionally, aripiprazole can increase GSK3β phosphorylation via the Dvl-GSK3β-β-catenin signalling pathway in the NAc, probably due to its relatively low intrinsic activity at D2Rs.
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The role of dopamine in the pathophysiology and treatment of apathy. PROGRESS IN BRAIN RESEARCH 2016; 229:389-426. [DOI: 10.1016/bs.pbr.2016.05.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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de Bartolomeis A, Tomasetti C, Iasevoli F. Update on the Mechanism of Action of Aripiprazole: Translational Insights into Antipsychotic Strategies Beyond Dopamine Receptor Antagonism. CNS Drugs 2015; 29:773-99. [PMID: 26346901 PMCID: PMC4602118 DOI: 10.1007/s40263-015-0278-3] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Dopamine partial agonism and functional selectivity have been innovative strategies in the pharmacological treatment of schizophrenia and mood disorders and have shifted the concept of dopamine modulation beyond the established approach of dopamine D2 receptor (D2R) antagonism. Despite the fact that aripiprazole was introduced in therapy more than 12 years ago, many questions are still unresolved regarding the complexity of the effects of this agent on signal transduction and intracellular pathways, in part linked to its pleiotropic receptor profile. The complexity of the mechanism of action has progressively shifted the conceptualization of this agent from partial agonism to functional selectivity. From the induction of early genes to modulation of scaffolding proteins and activation of transcription factors, aripiprazole has been shown to affect multiple cellular pathways and several cortical and subcortical neurotransmitter circuitries. Growing evidence shows that, beyond the consequences of D2R occupancy, aripiprazole has a unique neurobiology among available antipsychotics. The effect of chronic administration of aripiprazole on D2R affinity state and number has been especially highlighted, with relevant translational implications for long-term treatment of psychosis. The hypothesized effects of aripiprazole on cell-protective mechanisms and neurite growth, as well as the differential effects on intracellular pathways [i.e. extracellular signal-regulated kinase (ERK)] compared with full D2R antagonists, suggest further exploration of these targets by novel and future biased ligand compounds. This review aims to recapitulate the main neurobiological effects of aripiprazole and discuss the potential implications for upcoming improvements in schizophrenia therapy based on dopamine modulation beyond D2R antagonism.
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Affiliation(s)
- Andrea de Bartolomeis
- Unit of Treatment Resistant Psychosis, Laboratory of Molecular and Translational Psychiatry, Department of Neuroscience, University School of Medicine of Napoli "Federico II", Via Pansini, 5, Edificio n.18, 3rd floor, 80131, Naples, Italy.
| | - Carmine Tomasetti
- Unit of Treatment Resistant Psychosis, Laboratory of Molecular and Translational Psychiatry, Department of Neuroscience, University School of Medicine of Napoli "Federico II", Via Pansini, 5, Edificio n.18, 3rd floor, 80131, Naples, Italy
| | - Felice Iasevoli
- Unit of Treatment Resistant Psychosis, Laboratory of Molecular and Translational Psychiatry, Department of Neuroscience, University School of Medicine of Napoli "Federico II", Via Pansini, 5, Edificio n.18, 3rd floor, 80131, Naples, Italy
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Neural substrates underlying effort computation in schizophrenia. Neurosci Biobehav Rev 2013; 37:2649-65. [PMID: 24035741 DOI: 10.1016/j.neubiorev.2013.09.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 08/16/2013] [Accepted: 09/03/2013] [Indexed: 11/23/2022]
Abstract
The lack of initiative, drive or effort in patients with schizophrenia is linked to marked functional impairments. However, our assessment of effort and motivation is crude, relying on clinical rating scales based largely on patient recall. In order to better understand the neurobiology of effort in schizophrenia, we need more rigorous measurements of this construct. In the behavioural neuroscience literature, decades of work has been carried out developing various paradigms to examine the neural underpinnings of an animal's willingness to expend effort for a reward. Here, we shall review this literature on the nature of paradigms used in rodents to assess effort, as well as those used in humans. Next, the neurobiology of these effort-based decisions will be discussed. We shall then review what is known about effort in schizophrenia, and what might be inferred from experiments done in other human populations. Lastly, we shall discuss future directions of research that may assist in shedding light on the neurobiology of effort cost computations in schizophrenia.
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Jantschak F, Brosda J, Franke RT, Fink H, Möller D, Hübner H, Gmeiner P, Pertz HH. Pharmacological profile of 2-bromoterguride at human dopamine D2, porcine serotonin 5-hydroxytryptamine 2A, and α2C-adrenergic receptors, and its antipsychotic-like effects in rats. J Pharmacol Exp Ther 2013; 347:57-68. [PMID: 23863695 DOI: 10.1124/jpet.113.205997] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Dopaminergic, serotonergic, and adrenergic receptors are targets for therapeutic actions in schizophrenia. Dopamine D2 receptor partial agonists such as aripiprazole represent a treatment option for patients with this severe disorder. The ineffectiveness of terguride, another D2 receptor partial agonist, in treating schizophrenia was recently attributed to its considerably high intrinsic activity at D2 receptors. In this study, we used functional assays for recombinant D2 receptors and native 5-hydroxytryptamine 2A (5-HT2A), α2C-adrenergic, and histamine H1 receptors to compare the pharmacological properties of terguride and three of its halogenated derivatives (2-chloro-, 2-bromo-, 2-iodoterguride) with those of aripiprazole. Subsequently, we studied the antidopaminergic effects of 2-bromoterguride using amphetamine-induced locomotion (AIL). Its influence on spontaneous behavior was tested in the open field. Extrapyramidal side effect (EPS) liability was evaluated by catalepsy test. In a guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPγS) binding assay, 2-chloro-, 2-bromo-, and 2-iodoterguride produced intrinsic activities at human D2short (hD2S) receptors that were half as high as the intrinsic activity for terguride; aripiprazole lacked agonist activity. 2-Bromoterguride and aripiprazole activated D2S receptor-mediated inhibition of cAMP accumulation to the same extent; intrinsic activity was half as high as that of terguride. All compounds tested behaved as antagonists at human D2long/Gαo (hD2L/Gαo) receptors. Compared with aripiprazole, terguride and its derivatives displayed higher affinity at porcine 5-HT2A receptors and α2C-adrenoceptors and lower affinity at H1 receptors. 2-Bromoterguride inhibited AIL and did not induce catalepsy in rats. Because of its in vitro and in vivo properties, 2-bromoterguride may be a strong candidate for the treatment of schizophrenia with a lower risk to induce EPS.
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Affiliation(s)
- F Jantschak
- Institute of Pharmacy, Free University of Berlin, Berlin, Germany (F.J., H.H.P.); Institute of Pharmacology and Toxicology, School of Veterinary Medicine, Free University of Berlin, Berlin, Germany (J.B., R.T.F., H.F.); and Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Erlangen, Germany (D.M., H.H., P.G.)
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Miyamoto S, Miyake N, Jarskog LF, Fleischhacker WW, Lieberman JA. Pharmacological treatment of schizophrenia: a critical review of the pharmacology and clinical effects of current and future therapeutic agents. Mol Psychiatry 2012; 17:1206-27. [PMID: 22584864 DOI: 10.1038/mp.2012.47] [Citation(s) in RCA: 369] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Since the introduction of chlorpromazine and throughout the development of the new-generation antipsychotic drugs (APDs) beginning with clozapine, the D(2) receptor has been the target for the development of APDs. Pharmacologic actions to reduce neurotransmission through the D(2) receptor have been the only proven therapeutic mechanism for psychoses. A number of novel non-D(2) mechanisms of action of APDs have been explored over the past 40 years but none has definitively been proven effective. At the same time, the effectiveness of treatments and range of outcomes for patients are far from satisfactory. The relative success of antipsychotics in treating positive symptoms is limited by the fact that a substantial number of patients are refractory to current medications and by their lack of efficacy for negative and cognitive symptoms, which often determine the level of functional impairment. In addition, while the newer antipsychotics produce fewer motor side effects, safety and tolerability concerns about weight gain and endocrinopathies have emerged. Consequently, there is an urgent need for more effective and better-tolerated antipsychotic agents, and to identify new molecular targets and develop mechanistically novel compounds that can address the various symptom dimensions of schizophrenia. In recent years, a variety of new experimental pharmacological approaches have emerged, including compounds acting on targets other than the dopamine D(2) receptor. However, there is still an ongoing debate as to whether drugs selective for singe molecular targets (that is, 'magic bullets') or drugs selectively non-selective for several molecular targets (that is, 'magic shotguns', 'multifunctional drugs' or 'intramolecular polypharmacy') will lead to more effective new medications for schizophrenia. In this context, current and future drug development strategies can be seen to fall into three categories: (1) refinement of precedented mechanisms of action to provide drugs of comparable or superior efficacy and side-effect profiles to existing APDs; (2) development of novel (and presumably non-D(2)) mechanism APDs; (3) development of compounds to be used as adjuncts to APDs to augment efficacy by targeting specific symptom dimensions of schizophrenia and particularly those not responsive to traditional APD treatment. In addition, efforts are being made to determine if the products of susceptibility genes in schizophrenia, identified by genetic linkage and association studies, may be viable targets for drug development. Finally, a focus on early detection and early intervention aimed at halting or reversing progressive pathophysiological processes in schizophrenia has gained great influence. This has encouraged future drug development and therapeutic strategies that are neuroprotective. This article provides an update and critical review of the pharmacology and clinical profiles of current APDs and drugs acting on novel targets with potential to be therapeutic agents in the future.
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Affiliation(s)
- S Miyamoto
- Department of Neuropsychiatry, St Marianna University School of Medicine, Kawasaki, Japan
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Abstract
Psychopharmacology of schizophrenia has remained static for many years because the mechanisms explored have been basically monoaminergics, primarily focused toward the modification of dopaminergic function and, later on, serotonergic. In fact, most of the antipsychotics introduced in clinical practice in the last years have been antagonists or selective agonists of these receptors (D(2)/5-HT(2)). The exploration of other receptor pathways, and in particular those additionally involved in the action of the paradigmatic "atypical" antipsychotic clozapine (ie, cholinergic and noradrenergic), has not been very significant. Besides, research in the antipsychotics field has developed also by exploring pathways that are beyond the spectrum of clozapine. Among the most promising mechanisms are those based on the glutamatergic hypothesis of schizophrenia (agonists at the glycine-binding modulatory site of the N-methyl-D-aspartate receptor, glycine transporter inhibitors, modulators of the AMPA [α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid] receptor and selective agonists of the metabotropic receptor Glu(2)). Other less classic pathways are also under study and have led to some agents that are found in very early stages of development such as those acting on sigma receptors, cholecystokinin antagonists, neurotensin agonists, neurokinin receptor antagonists, GABAergic (+-aminobutyric acid [GABA]) enhancers, and cannabinoid(gamma-aminobutiric) receptor modulators.
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Kelleher JP, Centorrino F, Huxley NA, Bates JA, Drake JK, Egli S, Baldessarini RJ. Pilot randomized, controlled trial of pramipexole to augment antipsychotic treatment. Eur Neuropsychopharmacol 2012; 22:415-8. [PMID: 22153972 DOI: 10.1016/j.euroneuro.2011.10.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 10/18/2011] [Accepted: 10/19/2011] [Indexed: 11/20/2022]
Abstract
The preferential dopamine D(3)-agonist pramipexole (4.25±0.38 mg/day) or placebo were added for up to 12 weeks to ongoing antipsychotic treatment for 24 adult patients with DSM-IV schizophrenia or schizoaffective disorder. Pramipexole was generally well-tolerated (82% trial-completion), and yielded greater decreases in PANSS-total scores (drug/placebo=2.1; p=0.04), with similar decreases in PANSS positive and negative scores and 6.7-fold greater reduction of serum prolactin concentrations compared to placebo. There were no differences in ratings of mood, cognition or extrapyramidal symptoms, all of which were low at intake.
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Affiliation(s)
- James P Kelleher
- Department of Psychiatry, St. Vincent's Hospital Westchester, Harrison, NY 10528, USA.
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Chou HH, Twamley E, Swerdlow NR. Towards medication-enhancement of cognitive interventions in schizophrenia. Handb Exp Pharmacol 2012:81-111. [PMID: 23027413 PMCID: PMC3629915 DOI: 10.1007/978-3-642-25758-2_4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Current antipsychotic medications do little to improve real-life function in most schizophrenia patients. A dispassionate view of the dispersed and variable neuropathology of schizophrenia strongly suggests that it is not currently, and may never be, correctable with drugs. In contrast, several forms of cognitive therapy have been demonstrated to have modest but lasting positive effects on cognition, symptoms, and functional outcomes in schizophrenia patients. To date, attempts to improve clinical outcomes in schizophrenia by adding pro-cognitive drugs to antipsychotic regimens have had limited success, but we propose that a more promising strategy would be to pair drugs that enhance specific neurocognitive functions with cognitive therapies that challenge and reinforce those functions. By using medications that engage spared neural resources in the service of cognitive interventions, it might be possible to significantly enhance the efficacy of cognitive therapies. We review and suggest several laboratory measures that might detect potential pro-neurocognitive effects of drugs in individual patients, using a "test dose" design, aided by specific biomarkers predicting an individual's drug sensitivity. Lastly, we argue that drug classes viewed as "counter-intuitive" based on existing models for the pathophysiology of schizophrenia-including pro-catecholaminergic and NMDA-antagonistic drugs-might be important candidate "pro-cognitive therapy" drugs.
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Affiliation(s)
- Hsun-Hua Chou
- Department of Psychiatry, School of Medicine, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0804, USA
| | - Elizabeth Twamley
- Department of Psychiatry, School of Medicine, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0804, USA
| | - Neal R. Swerdlow
- Department of Psychiatry, School of Medicine, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0804, USA
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Comparative pharmacology of antipsychotics possessing combined dopamine D2 and serotonin 5-HT1A receptor properties. Psychopharmacology (Berl) 2011; 216:451-73. [PMID: 21394633 DOI: 10.1007/s00213-011-2247-y] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 02/22/2011] [Indexed: 02/07/2023]
Abstract
RATIONALE There is increasing interest in antipsychotics intended to manage positive symptoms via D(2) receptor blockade and improve negative symptoms and cognitive deficits via 5-HT(1A) activation. Such a strategy reduces side-effects such as the extrapyramidal syndrome (EPS), weight gain, and autonomic disturbance liability. OBJECTIVE This study aims to review pharmacological literature on compounds interacting at both 5-HT(1A) and D(2) receptors (as well as at other receptors), including aripiprazole, perospirone, ziprasidone, bifeprunox, lurasidone and cariprazine, PF-217830, adoprazine, SSR181507, and F15063. METHODS We examine data on in vitro binding and agonism and in vivo tests related to (1) positive symptoms (e.g., psychostimulant-induced hyperactivity or prepulse inhibition deficit), (2) negative symptoms (e.g., phencyclidine-induced social interaction deficits and cortical dopamine release), and (3) cognitive deficits (e.g., phencyclidine or scopolamine-induced memory deficits). EPS liability is assessed by measuring catalepsy and neuroendocrine impact by determining plasma prolactin, glucose, and corticosterone levels. RESULTS Compounds possessing "balanced" 5-HT(1A) receptor agonism and D(2) antagonism (or weak partial agonism) and, in some cases, combined with other beneficial properties, such as 5-HT(2A) receptor antagonism, are efficacious in a broad range of rodent pharmacological models yet have a lower propensity to elicit EPS or metabolic dysfunction. CONCLUSIONS Recent compounds exhibiting combined 5-HT(1A)/D(2) properties may be effective in treating a broader range of symptoms of schizophrenia and be better tolerated than existing antipsychotics. Nevertheless, further investigations are necessary to evaluate recent compounds, notably in view of their differing levels of 5-HT(1A) affinity and efficacy, which can markedly influence activity and side-effect profiles.
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Swerdlow NR. Are we studying and treating schizophrenia correctly? Schizophr Res 2011; 130:1-10. [PMID: 21645998 PMCID: PMC3139794 DOI: 10.1016/j.schres.2011.05.004] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 04/27/2011] [Accepted: 05/04/2011] [Indexed: 12/15/2022]
Abstract
New findings are rapidly revealing an increasingly detailed image of neural- and molecular-level dysfunction in schizophrenia, distributed throughout interconnected cortico-striato-pallido-thalamic circuitry. Some disturbances appear to reflect failures of early brain maturation, that become codified into dysfunctional circuit properties, resulting in a substantial loss of, or failure to develop, both cells and/or appropriate connectivity across widely dispersed brain regions. These circuit disturbances are variable across individuals with schizophrenia, perhaps reflecting the interaction of multiple different risk genes and epigenetic events. Given these complex and variable hard-wired circuit disturbances, it is worth considering how new and emerging findings can be integrated into actionable treatment models. This paper suggests that future efforts towards developing more effective therapeutic approaches for the schizophrenias should diverge from prevailing models in genetics and molecular neuroscience, and focus instead on a more practical three-part treatment strategy: 1) systematic rehabilitative psychotherapies designed to engage healthy neural systems to compensate for and replace dysfunctional higher circuit elements, used in concert with 2) medications that specifically target cognitive mechanisms engaged by these rehabilitative psychotherapies, and 3) antipsychotic medications that target nodal or convergent circuit points within the limbic-motor interface, to constrain the scope and severity of psychotic exacerbations and thereby facilitate engagement in cognitive rehabilitation. The use of targeted cognitive rehabilitative psychotherapy plus synergistic medication has both common sense and time-tested efficacy with numerous other neuropsychiatric disorders.
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Affiliation(s)
- Neal R Swerdlow
- School of Medicine, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0804, United States.
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Tadori Y, Forbes RA, McQuade RD, Kikuchi T. In vitro pharmacology of aripiprazole, its metabolite and experimental dopamine partial agonists at human dopamine D2 and D3 receptors. Eur J Pharmacol 2011; 668:355-65. [PMID: 21816144 DOI: 10.1016/j.ejphar.2011.07.020] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 06/04/2011] [Accepted: 07/07/2011] [Indexed: 10/17/2022]
Abstract
Aripiprazole is the first dopamine D(2)/D(3) receptor partial agonist successfully developed and ultimately approved for treatment of a broad spectrum of psychiatric and neurological disorders. Aripiprazole's dopamine D(2) and serotonin 5-HT(1A) receptor partial agonist activities have been postulated to confer clinical efficacy without marked sedation, and a relatively favorable overall side-effect profile. Using aripiprazole's unique profile as a benchmark for new dopamine partial agonist development may facilitate discovery of new antipsychotics. We conducted an in vitro comparative analysis between aripiprazole, and its human metabolite OPC-14857 (7-(4-[4-(2,3-dichlorophenyl)-1-piperazinyl)butoxy)-2(1H)-quinolinone)); RGH-188 (trans-1-[4-[2-[4-(2,3-dichlorophenyl)piperazine-1-yl]ethyl]cyclohexyl]-3,3-dimethylurea), and its metabolite didesmethyl-RGH-188 (DDM-RGH-188); as well as bifeprunox, sarizotan, N-desmethylclozapine (NDMC; clozapine metabolite), and SDZ 208-912 (N-[(8α)-2-chloro-6-methylergolin-8-yl]-2,2-dimethylpropanamide). In vitro pharmacological assessment included inhibition of forskolin-stimulated cAMP accumulation and the reversal of dopamine-induced inhibition in clonal Chinese hamster ovary cell lines expressing D(2S), D(2L), D(3) Ser-9 and D(3) Gly-9 for human dopamine receptors. All test compounds behaved as dopamine D(2)/D(3) receptor partial agonists. Aripiprazole's intrinsic activity at dopamine D(2S) and D(2L) receptors was similar to that of OPC-14857 and RGH-188; lower than that of dopamine and bifeprunox; and higher than that of DDM-RGH-188, SDZ 208-912, sarizotan, and NDMC. Aripiprazole's intrinsic activity at dopamine D(3) Ser-9 and D(3) Gly-9 receptors was similar to that of OPC-14857 and sarizotan; lower than that of dopamine, bifeprunox, RGH-188 and DDM-RGH-188; and higher than that of SDZ 208-912 and NDMC. A consolidated assessment of these findings may help defining the most appropriate magnitude of intrinsic activity at dopamine D(2)/D(3) receptors for clinical efficacy and safety.
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Affiliation(s)
- Yoshihiro Tadori
- Quests Research Institute, Otsuka Pharmaceutical Co., Ltd., Tokushima, 771-0192, Japan.
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Dyck B, Guest K, Sookram C, Basu D, Johnson R, Mishra RK. PAOPA, a potent analogue of Pro-Leu-glycinamide and allosteric modulator of the dopamine D2 receptor, prevents NMDA receptor antagonist (MK-801)-induced deficits in social interaction in the rat: implications for the treatment of negative symptoms in schizophrenia. Schizophr Res 2011; 125:88-92. [PMID: 21036015 PMCID: PMC3010311 DOI: 10.1016/j.schres.2010.09.025] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 09/28/2010] [Accepted: 09/29/2010] [Indexed: 01/27/2023]
Abstract
The aim of this study was to investigate whether a potent analogue of the endogenous brain peptide l-prolyl-l-leucyl-glycinamide (PLG), (3(R)-[(2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide (PAOPA), can prevent the induction of social withdrawal caused by sub-chronic treatment with the non-competitive NMDA (N-methyl-l-aspartate) receptor antagonist, MK-801. Results indicate that MK-801 (0.5 mg/kg) significantly decreased social interaction following sub-chronic treatment (7 days). Treatment with PAOPA (1 mg/kg) blocked the effects of MK-801, and increased the amount of time spent in social interaction in comparison to control animals. These results provide evidence for the development of peptidomimetic compounds for the treatment of social withdrawal and related negative symptoms associated with schizophrenia.
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Affiliation(s)
- Bailee Dyck
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | - Kelly Guest
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | - Christal Sookram
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | - Dipannita Basu
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | - Rodney Johnson
- Department of Medicinal Chemistry, University of Minnesota, MI, USA
| | - Ram K. Mishra
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
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Costentin J. Une nouvelle approche de la prise en charge de la schizophrénie : les agonistes partiels des récepteurs D2 de la dopamine. ANNALES PHARMACEUTIQUES FRANÇAISES 2009; 67:310-9. [DOI: 10.1016/j.pharma.2009.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 05/25/2009] [Indexed: 10/20/2022]
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NAKAI SATORU, HIROSE TSUYOSHI, MORI TOYOKI, STARK ARLENE, ARAKI HIROAKI, KIKUCHI TETSURO. THE EFFECT OF ARIPIPRAZOLE ON PREPULSE INHIBITION OF THE STARTLE RESPONSE IN NORMAL AND HYPERDOPAMINERGIC STATES IN RATS. Int J Neurosci 2009; 118:39-57. [DOI: 10.1080/00207450601041989] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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20
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Zhang TT, Song M, Hang TJ, Xu XF, Wen AD, Yang L, Jia L. Pharmacokinetic profile of talipexole in healthy volunteers is not altered when it is co-administered with Madopar (co-beneldopa). J Clin Pharm Ther 2009; 34:345-54. [DOI: 10.1111/j.1365-2710.2008.01008.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Gentile S. A systematic review of quality of life and weight gain-related issues in patients treated for severe and persistent mental disorders: focus on aripiprazole. Neuropsychiatr Dis Treat 2009; 5:117-25. [PMID: 19557106 PMCID: PMC2695224 DOI: 10.2147/ndt.s4167] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Aripiprazole is a relatively novel second-generation antipsychotic belonging to the chemical class of benzisoxazole derivatives and is characterized by a unique pharmacological profile which suggests that the drug acts as a dopamine-serotonin system stabilizer. Whereas all previously available antipsychotics are antagonists at D(2) receptors, aripiprazole is the only available partial agonist at these receptors. Thus, it has been suggested that aripiprazole could be associated with a relatively neutral impact on bodyweight, possibly reducing risks of a detrimental impact on the quality of life that often complicates management for a large number of patients diagnosed with severe and persistent mental disorders (SPMDs) treated chronically with antipsychotic medications. However, data from short- and long-term reviewed studies indicate that the prevalence rate of clinically relevant weight gain during therapy with this drug is similar to that occurring during treatments with other antipsychotic agents, either typical or atypical. Moreover, information on the impact of aripiprazole therapy on the quality of life of patients diagnosed with SPMDs is scarce and characterized by conflicting results. Given these results, further, large, well-designed studies are needed before confirming potential advantages of aripiprazole over first-generation antipsychotics and other SGAs.
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Affiliation(s)
- Salvatore Gentile
- Department of Mental Health, ASL Salerno 1, Mental Health Center n 4, Piazza Galdi, 841013 Cava de’ Tirreni (Salerno), Italy.
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Dahan L, Husum H, Mnie-Filali O, Arnt J, Hertel P, Haddjeri N. Effects of bifeprunox and aripiprazole on rat serotonin and dopamine neuronal activity and anxiolytic behaviour. J Psychopharmacol 2009; 23:177-89. [PMID: 18515444 DOI: 10.1177/0269881108089586] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The atypical antipsychotic bifeprunox is a partial dopamine D(2) and 5-HT(1A) receptor agonist. Using in-vivo electrophysiological and behavioural paradigms in the rat, the effects of bifeprunox and aripiprazole were assessed on ventral tegmental area (VTA) dopamine and dorsal raphe serotonin (5-HT) cell activity and on foot shock-induced ultrasonic vocalisation (USV). In VTA, bifeprunox and aripiprazole decreased (by 20-50%) firing of dopamine neurons. Interestingly, bursting activity was markedly reduced (by 70-100%), bursting being associated with a larger synaptic dopamine release than single spike firing. Both ligands reduced inhibition of firing rate induced by the full dopamine receptor agonist apomorphine, whereas the D(2) receptor antagonist haloperidol prevented these inhibitory effects, confirming partial D(2)-like agonistic properties. On 5-HT neurons, bifeprunox was more potent than aripiprazole to suppress firing activity. The 5-HT(1A) receptor antagonist WAY-100,635 prevented their effects. In the USV test of anxiolytic-like activity, bifeprunox had higher potency than aripiprazole to reduce vocalisations. Both WAY-100,635 and haloperidol reversed the effects of both agonists. The present in-vivo study shows that bifeprunox is a potent partial D(2)-like and 5-HT(1A) receptor agonist reducing preferentially the phasic activity of dopamine neurons. Thus, bifeprunox would be expected to be an effective compound against positive and negative symptoms of schizophrenia.
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Affiliation(s)
- L Dahan
- Laboratory of Neuropharmacology, Faculty of Pharmacy, University of Claude Bernard Lyon I, Lyon, France
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Marino MJ, Knutsen LJS, Williams M. Emerging Opportunities for Antipsychotic Drug Discovery in the Postgenomic Era. J Med Chem 2008; 51:1077-107. [PMID: 18198826 DOI: 10.1021/jm701094q] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Michael J. Marino
- Worldwide Discovery Research, Cephalon, Inc., 145 Brandywine Parkway, West Chester, Pennsylvania 19380
| | - Lars J. S. Knutsen
- Worldwide Discovery Research, Cephalon, Inc., 145 Brandywine Parkway, West Chester, Pennsylvania 19380
| | - Michael Williams
- Worldwide Discovery Research, Cephalon, Inc., 145 Brandywine Parkway, West Chester, Pennsylvania 19380
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Tadori Y, Kitagawa H, Forbes RA, McQuade RD, Stark A, Kikuchi T. Differences in agonist/antagonist properties at human dopamine D(2) receptors between aripiprazole, bifeprunox and SDZ 208-912. Eur J Pharmacol 2007; 574:103-11. [PMID: 17692841 DOI: 10.1016/j.ejphar.2007.07.031] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Revised: 06/29/2007] [Accepted: 07/18/2007] [Indexed: 11/22/2022]
Abstract
Aripiprazole is the first dopamine D(2) receptor partial agonist approved for use in schizophrenia and bipolar disorder. Other partial agonists have failed in various stages of development, either for reasons of poor tolerability or lack of efficacy. We conducted an in vitro comparative analysis between aripiprazole, bifeprunox, SDZ 208-912, OPC-4392 and ACR16 in attempt to correlate specific pharmacological properties with clinical outcome. In vitro pharmacological assessment included inhibition of forskolin-stimulated cAMP accumulation and the reversal of this inhibition produced by dopamine in clonal CHO cell lines expressing high and low densities of human dopamine D(2L) and D(2S) receptors. In cells expressing high receptor densities, all drugs except ACR16 predominantly behaved as agonists. However, in cells expressing low receptor densities, all drugs showed significantly lower maximal effects than dopamine. Aripiprazole's intrinsic activity was lower than that observed with bifeprunox and OPC-4392, and higher than that of SDZ 208-912. Aripiprazole's antagonist activity was greater than that of bifeprunox and OPC-4392, and less than that of SDZ 208-912. In conclusion, our data suggests that aripiprazole's unique intrinsic activity profile may account for its demonstrated clinical efficacy in the treatment of both positive and negative symptoms of schizophrenia, as well as its demonstrated low liability for parkinsonism and hyperprolactinemia. A higher degree of intrinsic activity, and lower relative antagonist activity, such as that observed with bifeprunox and OPC-4392 may translate into a clinically suboptimal improvement of positive symptoms. SDZ 208-912's intrinsic activity may be lower than the optimal level needed to minimize extrapyramidal symptoms.
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Affiliation(s)
- Yoshihiro Tadori
- Quests Research Institute, Otsuka Pharmaceutical Co., Ltd., 463-10 Kagasuno, Kawauchi-cho, Tokushima, 771-0192, Japan.
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Jordan S, Regardie K, Johnson JL, Chen R, Kambayashi J, McQuade R, Kitagawa H, Tadori Y, Kikuchi T. In vitro functional characteristics of dopamine D2 receptor partial agonists in second and third messenger-based assays of cloned human dopamine D2Long receptor signalling. J Psychopharmacol 2007; 21:620-7. [PMID: 17092971 DOI: 10.1177/0269881106072090] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Aripiprazole, (+)terguride, OPC-4392 and (-)3-PPP have been classified as dopamine D(2) receptor partial agonists based largely on their activity in second messenger-based assays of dopamine D(2) receptor signalling. Nevertheless, signal transduction amplification might result in these compounds behaving as dopamine D(2) receptor full agonists at a more downstream level of signalling. We compared the intrinsic activity (E(max), expressed as a percentage of the maximal effect of dopamine) of aripiprazole, (+)terguride, OPC-4392 and (-)3-PPP using second (calcium (Ca(2+)) mobilization) and third (extracellular signal-regulated kinase 2 (ERK2) phosphoprotein expression) messenger readouts of cloned human dopamine D(2long) (hD(2L)) receptor signalling in CHO cells. These compounds were all less potent and displayed lower intrinsic activity in the Ca(2+) assay (aripiprazole = 24.3%, (+)terguride = 56.9%, OPC-4392 = 58.6% and (-)3-PPP = 75.1%), and aripiprazole (E(max) = 54.5%) displayed a substantially lower intrinsic activity than (+)terguride (E(max) = 92.3%), OPC-4392 (E(max) = 93.1%) and (-)3-PPP (E(max) = 101.1%) in the more downstream-based ERK2 phosphoprotein expression assay. These drug effects on Ca(2+) mobilization and ERK2 phosphoprotein expression were mediated through dopamine hD(2L) receptors, as they all were blocked by (-)raclopride, whereas (-)raclopride and other dopamine D(2) receptor antagonists (haloperidol, risperidone, ziprasidone, olanzapine, clozapine and quetiapine) were inactive on their own in both assays. These data are consistent with clinical evidence that only dopamine D(2) receptor partial agonists with a sufficiently low enough intrinsic activity will prove effective against the positive symptoms of schizophrenia, and also highlight the importance of using downstream-based assays in the discovery of novel D(2) receptor partial agonist therapeutics.
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Affiliation(s)
- Shaun Jordan
- Department of Neuroscience Research, Otsuka Maryland Medicinal Laboratories, 9900 Medical Center Drive, Rockville, MD 20850, USA.
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26
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Jordan S, Johnson JL, Regardie K, Chen R, Koprivica V, Tadori Y, Kambayashi J, Kitagawa H, Kikuchi T. Dopamine D2 receptor partial agonists display differential or contrasting characteristics in membrane and cell-based assays of dopamine D2 receptor signaling. Prog Neuropsychopharmacol Biol Psychiatry 2007; 31:348-56. [PMID: 17070976 DOI: 10.1016/j.pnpbp.2006.09.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 07/20/2006] [Accepted: 09/13/2006] [Indexed: 01/09/2023]
Abstract
Clinical evidence suggests that dopamine D(2) receptor partial agonists must have a sufficiently low intrinsic activity to be effective as antipsychotics. Here, we used dopamine D(2) receptor signaling assays to compare the in vitro functional characteristics of the antipsychotic aripiprazole with other dopamine D(2) receptor partial agonists (7-{3-[4-(2,3-dimethylphenyl)-piperazinyl]propoxy}-2(1H)-quinolinone [OPC-4392], (-)-3-(3-hydroxy-phenyl)-N-n-propylpiperidine [(-)3-PPP] and (+)terguride) and dopamine D(2) receptor antagonists. Aripiprazole and OPC-4392 were inactive in a guanosine-5'-O-(3-[(35)S]thio)-triphosphate ([(35)S]GTPgammaS) binding assay using Chinese Hamster Ovary (CHO) cell membranes expressing cloned human dopamine D(2Long) (hD(2L)) receptors, whereas (-)3-PPP and (+)terguride displayed low intrinsic activity. Aripiprazole also had no effect on [(35)S]GTPgammaS binding to CHO-hD(2L) cells, while OPC-4392, (-)3-PPP and (+)terguride were partial agonists. In contrast, aripiprazole, OPC-4392, (-)3-PPP, and (+)terguride were inactive in a [(35)S]GTPgammaS binding assay using rat striatal membranes. However, at a more downstream level of CHO-hD(2L) cell signalling, these drugs all behaved as dopamine hD(2L) receptor partial agonists, with aripiprazole displaying an intrinsic activity 2 to 3-fold lower (inhibition of forskolin-induced adenosine 3',5'-cyclic monophosphate accumulation) and almost half as high (enhancement of adenosine triphosphate-stimulated [(3)H]arachidonic acid release) as OPC-4392, (-)3-PPP and (+)terguride. Dopamine activity was blocked in each case by (-)raclopride, which was inactive on its own in every assay, as were the antipsychotics haloperidol, olanzapine, ziprasidone and clozapine. Together, these data, whilst preclinical in nature, are consistent with clinical evidence suggesting the favorable antipsychotic profile of aripiprazole, compared with the other clinically ineffective partial agonists, is dependent on its low intrinsic activity at dopamine D(2) receptors. This study also highlights the limitations of using [(35)S]GTPgammaS binding assays to identify dopamine D(2) receptor partial agonists.
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Affiliation(s)
- Shaun Jordan
- Department of Neuroscience Research, Otsuka Maryland Medicinal Laboratories, 9900 Medical Center Drive, Rockville, MD 20850, USA.
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27
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Dopamine D2 receptor-mediated G protein activation assessed by agonist-stimulated [35S]guanosine 5'-O-(gamma-thiotriphosphate) binding in rat striatal membranes. Prog Neuropsychopharmacol Biol Psychiatry 2006; 30:1304-12. [PMID: 16824659 DOI: 10.1016/j.pnpbp.2006.05.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Revised: 05/09/2006] [Accepted: 05/09/2006] [Indexed: 11/29/2022]
Abstract
In order to investigate the functional interaction between the native dopamine receptors and their coupled guanine nucleotide-binding regulatory (G) proteins, dopamine-stimulated [(35)S]guanosine 5'-O-(gamma-thiotriphosphate) ([(35)S]GTPgammaS) binding was pharmacologically characterized in rat striatal membranes. Following optimizing the experimental conditions as to the concentrations of GDP, MgCl(2) and NaCl in the assay medium, the agonist and antagonist properties for a series of dopamine receptor ligands were determined mainly under the standard assay condition. The pharmacological profile of this response clearly indicated the involvement of dopamine D(2)-like receptors, but not of dopamine D(1)-like receptors. Among the types of dopamine D(2)-like receptors, dopamine D(2) receptors most likely appeared to be involved in dopamine-stimulated [(35)S]GTPgammaS binding in rat striatal membranes, because the affinities of agonists and antagonists determined in the present study were significantly correlated with those reported in the previous literature only for dopamine D(2) receptors, but not for dopamine D(3) or D(4) types. Though the concentration-dependent inhibition curves of dopamine-stimulated [(35)S]GTPgammaS binding by spiperone and S(-)-raclopride were apparently biphasic, the origin of the low-affinity minor components was not fully determined. The antiparkinsonian drugs with the properties of dopamine receptor agonism were shown to behave as stimulants with varied affinities and relative efficacies in the current assay system. On the other hand, neither phencyclidine (PCP) nor ketamine stimulated the specific [(35)S]GTPgammaS binding, in contrast with the previous report demonstrating that these two N-methyl-D-aspartic acid (NMDA) receptor antagonists behaved as agonists at human dopamine D(2) receptors expressed in Chinese hamster ovary (CHO) cells. These results provide important information about the functional activation of G proteins coupled with dopamine D(2) receptors as well as agonist actions of various compounds at native dopamine D(2) receptors, which are potentially involved in pathophysiology and pharmacotherapy of neuropsychiatric diseases such as Parkinson's disease, schizophrenia and depression.
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28
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Heinrich JN, Brennan J, Lai MH, Sullivan K, Hornby G, Popiolek M, Jiang LX, Pausch MH, Stack G, Marquis KL, Andree TH. Aplindore (DAB-452), a high affinity selective dopamine D2 receptor partial agonist. Eur J Pharmacol 2006; 552:36-45. [PMID: 17056032 DOI: 10.1016/j.ejphar.2006.08.063] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Revised: 08/25/2006] [Accepted: 08/29/2006] [Indexed: 11/17/2022]
Abstract
The pharmacology of aplindore (DAB-452) was characterized in CHO-K1 cells stably transfected with the human dopamine D(2) receptor short isoform (CHO-D(2s)) and in a behavioral model for post-synaptic agonism in rats. In [(3)H]-spiperone competition binding studies, aplindore showed high affinity for dopamine D(2) and D(3) receptors and low affinity for the dopamine D(4), serotonin (5-HT)(1A), 5-HT(2) receptors and the alpha1-adrenoceptor. The high potency partial agonist activity of aplindore was demonstrated in [(35)S]guanosine 5'-O-(3-thiotriphosphate) ([(35)S]GTPgammaS) binding, extracellular signal-regulated kinase (ERK)-phosphorylation and intracellular calcium flux assay using fluorometric plate reader ([Ca(2+)](i)-FLIPR) format. The [Ca(2+)](i)-FLIPR assay was conducted with CHO-D(2S) receptor cells also stably expressing chimeric G(alphaq/o)-proteins. In all assay modalities, the potencies and intrinsic activities of aplindore were lower than dopamine and higher than aripiprazole. In contrast to the [(35)S]GTPgammaS binding and ERK-phosphorylation assays, the [Ca(2+)](i)-FLIPR assay was able to detect the low partial agonist activity of SDZ 208-912. In unilaterally 6-hydroxydopamine (6-OHDA) lesioned rats, aplindore induced contralateral turning, which was blocked by the dopamine D(2) receptor antagonist raclopride. The dopamine D(2) receptor selective partial agonist profile of aplindore suggests that it should be effective for the treatment of dopaminergic-based disorders, such as schizophrenia and Parkinson's disease.
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MESH Headings
- Animals
- Binding, Competitive
- CHO Cells
- Calcium/metabolism
- Cricetinae
- Cricetulus
- Dopamine Agonists/metabolism
- Dopamine Agonists/pharmacology
- Dose-Response Relationship, Drug
- Extracellular Signal-Regulated MAP Kinases/metabolism
- GTP-Binding Protein alpha Subunits/genetics
- GTP-Binding Protein alpha Subunits/metabolism
- Guanosine 5'-O-(3-Thiotriphosphate)/metabolism
- Indoles/metabolism
- Indoles/pharmacology
- Male
- Motor Activity/drug effects
- Oxidopamine/toxicity
- Phosphorylation/drug effects
- Quinpirole/pharmacology
- Radioligand Assay
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT1A/metabolism
- Receptors, Adrenergic, alpha-1/metabolism
- Receptors, Dopamine D2/agonists
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
- Receptors, Dopamine D4/metabolism
- Receptors, Serotonin, 5-HT2/metabolism
- Substantia Nigra/drug effects
- Substantia Nigra/pathology
- Substantia Nigra/physiopathology
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Affiliation(s)
- Julia N Heinrich
- Discovery Neuroscience, Wyeth Research, CN8000, Princeton, NJ 08543-8000, USA.
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Kelly DL, Conley RR, Carpenter WT. First-episode schizophrenia: a focus on pharmacological treatment and safety considerations. Drugs 2005; 65:1113-38. [PMID: 15907146 DOI: 10.2165/00003495-200565080-00006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Schizophrenia is a debilitating disorder, which is usually chronic, and is one of the most devastating medical illnesses. Early and appropriate treatment with antipsychotics is an important strategy for patients with first-episode schizophrenia. However, there are many possible safety issues for patients with schizophrenia that should be considered and properly addressed. Depressive symptoms and suicidal behaviour commonly occur in first-episode schizophrenic patients, and every effort should be made to treat and minimise these symptoms. There are also important issues and considerations in young and first-episode patients that should also be considered in the emergency treatment setting and for minimising medication nonadherence in this population. Most importantly, adverse effects should be considered, minimised and addressed. While first- and second-generation antipsychotics (SGAs) both appear to offer similar efficacy for amelioration of positive symptoms in first-episode patients, SGAs may offer better tolerability, specifically regarding extrapyramidal symptoms (EPS) and tardive dyskinesia risk, and some prolactin-sparing benefits. However, these medications do cause a host of adverse effects, including weight gain, metabolic disturbances, corrected QT interval prolongation and prolactin-related adverse effects, which are important considerations relating to both the short- and long-term safety of patients with schizophrenia being treated with SGAs. Clozapine and olanzapine are most likely to cause weight gain and metabolic effects, while risperidone is more likely to cause EPS and prolactin elevations. Most antipsychotics should be used in low doses to minimise adverse effects and each medication should be optimised in a highly individualised way to maximise adherence and treatment outcomes and minimise tolerability and safety concerns. At some point in their lives, these patients will most probably experience periods of depression, suicidal behaviours, adverse effects and nonadherence, and every effort should be made to minimise or prevent these from occurring. Thus, safety concerns in this group of young patients, in the beginning of their first psychotic episode, are a major issue as they are starting a journey of antipsychotic treatment that is likely to last for the remainder of their lives.
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Affiliation(s)
- Deanna L Kelly
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, Maryland 21228, USA.
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30
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Tadori Y, Miwa T, Tottori K, Burris KD, Stark A, Mori T, Kikuchi T. Aripiprazole's low intrinsic activities at human dopamine D2L and D2S receptors render it a unique antipsychotic. Eur J Pharmacol 2005; 515:10-9. [PMID: 15894311 DOI: 10.1016/j.ejphar.2005.02.051] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2004] [Revised: 01/31/2005] [Accepted: 02/02/2005] [Indexed: 01/23/2023]
Abstract
Aripiprazole is the first clinically approved atypical antipsychotic agent having dopamine D2 receptor partial agonist activities. To evaluate aripiprazole's agonist and antagonist properties, we established a Chinese hamster ovary cell line expressing high and low densities of the long and short isoforms of human dopamine D2 receptors, then compared its properties with 7-{3-[4-(2,3-dimethylphenyl)piperazinyl]propoxy}-2(1H)-quinolinone (OPC-4392), S(-)-3-(3-hydroxyphenyl)-N-n-propylpiperidine ((-)-3-PPP), and terguride (other partial agonists) using forskolin-stimulated cAMP accumulation as an index. In cells expressing high receptor densities, all partial agonists predominantly behaved as agonists. However, in cells expressing low receptor densities, the partial agonists showed significantly lower maximal effects than dopamine. Aripiprazole showed the lowest intrinsic activities. In addition, all compounds blocked the action of dopamine with a maximum effect equal to that of each compound alone. Aripiprazole's low intrinsic activities may account for the clinical finding that, unlike the other partial agonists, it is substantially active against both positive and negative symptoms of schizophrenia.
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Affiliation(s)
- Yoshihiro Tadori
- Research Institute of Pharmacological and Therapeutical Development, Otsuka Pharmaceutical Co., Ltd., Tokushima 771-0192, Japan.
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Culm KE, Lugo-Escobar N, Hope BT, Hammer RP. Repeated quinpirole treatment increases cAMP-dependent protein kinase activity and CREB phosphorylation in nucleus accumbens and reverses quinpirole-induced sensorimotor gating deficits in rats. Neuropsychopharmacology 2004; 29:1823-30. [PMID: 15138441 DOI: 10.1038/sj.npp.1300483] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Sensorimotor gating, which is severely disrupted in schizophrenic patients, can be measured by assessing prepulse inhibition of the acoustic startle response (PPI). Acute administration of D2-like receptor agonists such as quinpirole reduces PPI, but tolerance occurs upon repeated administration. In the present study, PPI in rats was reduced by acute quinpirole (0.1 mg/kg, s.c.), but not following repeated quinpirole treatment once daily for 28 days. Repeated quinpirole treatment did not alter the levels of basal-, forskolin- (5 microM), or SKF 82958- (10 microM) stimulated adenylate cyclase activity in the nucleus accumbens (NAc), but significantly increased cAMP-dependent protein kinase (PKA) activity. Phosphorylation of cAMP response element-binding protein (CREB) was significantly greater in the NAc after repeated quinpirole treatment than after repeated saline treatment with or without acute quinpirole challenge. Activation of PKA by intra-accumbens infusion of the cAMP analog, Sp-cAMPS, prevented acute quinpirole-induced PPI disruption, similar to the behavioral effect observed following repeated quinpirole treatment. Thus, repeated quinpirole treatment increases NAc PKA activity and CREB phosphorylation, and this neuroadaptive response might facilitate the recovery of sensorimotor gating in schizophrenia.
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Affiliation(s)
- Kerry E Culm
- Department of Pharmacology, Tufts University School of Medicine, Boston, MA, USA
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Roth BL, Sheffler DJ, Kroeze WK. Magic shotguns versus magic bullets: selectively non-selective drugs for mood disorders and schizophrenia. Nat Rev Drug Discov 2004; 3:353-9. [PMID: 15060530 DOI: 10.1038/nrd1346] [Citation(s) in RCA: 837] [Impact Index Per Article: 41.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Bryan L Roth
- Department of Biochemistry, School of Medicine, Case Western Reserve University, 2109 Adelbert Road, Cleveland, Ohio 44106, USA.
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Jaskiw GE, Popli AP. A meta-analysis of the response to chronic L-dopa in patients with schizophrenia: therapeutic and heuristic implications. Psychopharmacology (Berl) 2004; 171:365-74. [PMID: 14668973 DOI: 10.1007/s00213-003-1672-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2002] [Accepted: 10/01/2003] [Indexed: 11/26/2022]
Abstract
RATIONALE While it is generally believed that administration of the dopamine precursor levodopa ( L-dopa) exacerbates symptoms of schizophrenia, numerous reports suggest that adjunctive L-dopa may be beneficial. This body of literature has not been critically reviewed. OBJECTIVES On the basis of published studies, to determine whether L-dopa administered concomitantly with antipsychotic drugs provides a beneficial response in patients with schizophrenia. METHODS This review examined 30 studies involving 716 patients. Due to wide methodological variability and limited statistical information, only five studies encompassing 160 patients could be included in a meta-analysis. The others were evaluated qualitatively. RESULTS When L-dopa was added to antipsychotic drugs, the overall improvement was moderate ( d=0.71) and highly significant ( P<0.0001). There were 16 other studies in which L-dopa was added to antipsychotic drugs, but which did not meet criteria for inclusion in the meta-analysis. In these, worsening occurred in less than 20% of patients; the percentage of improved patients varied widely but had a central tendency around 50%. CONCLUSIONS . In patients already on antipsychotic drugs, the addition of L-dopa can be beneficial. Dopamine agonists merit further consideration as adjuncts to antipsychotic drugs in the treatment of schizophrenia.
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Affiliation(s)
- George E Jaskiw
- Psychiatry Service 116 A(B), Louis Stokes Cleveland VAMC, 10000 Brecksville Road, Brecksville, OH 44141, USA.
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Abstract
Before the 1990s, treatment of psychoses centered on conventional agents whose tolerability was limited by extrapyramidal side effects (EPS). The past decade has seen the emergence of a newer generation of antipsychotic agents, first with clozapine and followed shortly by risperidone, olanzapine, quetiapine, and ziprasidone. These agents have been touted as providing better negative symptom efficacy, less impaired cognition, and lower risk of extrapyramidal syndromes. However, evolving evidence suggests that several drugs in this class may be associated with significant weight gain and lipid abnormalities. Aripiprazole, a new atypical antipsychotic drug, displayed efficacy similar to that of haloperidol and risperidone and superior to that of placebo in numerous clinical trials. Aripiprazole does not cause significant prolactin elevation and is associated with a low rate of clinically significant weight gain compared with other atypical antipsychotics. Patients receiving aripiprazole experienced EPS at a rate similar to that seen with placebo. Aripiprazole provides a new treatment option with limited adverse effects for patients in need of antipsychotic therapy.
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Affiliation(s)
- Tami R Argo
- College of Pharmacy, University of Iowa, Iowa City, Iowa 52242-1112, USA
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Fleischhacker WW. New developments in the pharmacotherapy of schizophrenia. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2003:105-17. [PMID: 12830932 DOI: 10.1007/978-3-7091-6020-6_7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
This review summarizes current key research strategies and the most prominently pursued new potential treatments for schizophrenia. First, new routes of administration for second generation antipsychotics are presented. These include rapidly dissolving tablets, drops and sirups as well as new intramuscular formulations. Newly available short acting and long acting (depot) antipsychotics complement oral antipsychotics so that the full spectrum of routes of administration is now available for second generation antipsychotics. Next to antipsychotic polypharmacy, in which two or more antipsychotics are combined, pharmacological add-on treatments, mainly with benzodiazepines, antidepressants and mood stabilizers enjoy increasing popularity. Most of this practice is driven by personal preferences, clinical experience and marketing rather than evidence based medicine. New pharmacological mechanisms currently utilized in advanced states of development include partial dopamine D2-receptor agonism, supplementation with glutamatergic agents, estrogen and omega-3-fatty acids. While the concept of partial D1-agonism has already led to the successful launch of a new antipsychotic, aripiprazole, the other attempts to improve therapeutic response in schizophrenia patients have so far provided equivocal results. It is argued that they may be helpful for certain subgroups or specific symptoms of schizophrenia patients. In conclusion, many exciting new pharmacological leads are currently pursued and this will very likely augment the options for treating patients with schizophrenia.
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Affiliation(s)
- W W Fleischhacker
- Department of Biological Psychiatry, Innsbruck University Clinics, Innsbruck, Austria.
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Newman-Tancredi A, Cussac D, Brocco M, Rivet JM, Chaput C, Touzard M, Pasteau V, Millan MJ. Dopamine D2 receptor-mediated G-protein activation in rat striatum: functional autoradiography and influence of unilateral 6-hydroxydopamine lesions of the substantia nigra. Brain Res 2001; 920:41-54. [PMID: 11716810 DOI: 10.1016/s0006-8993(01)02927-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Unilateral 6-hydroxydopamine (6-OHDA) lesions of substantia nigra pars compacta (SNPC) neurons in rats induce behavioural hypersensitivity to dopaminergic agonists. However, the role of specific dopamine receptors is unclear, and potential alterations in their transduction mechanisms remain to be evaluated. The present study addressed these issues employing the dopaminergic agonist, quinelorane, which efficaciously stimulated G-protein activation (as assessed by [35S]GTPgammaS binding) at cloned hD2 (and hD3) receptors. At rat striatal membranes, dopamine stimulated [35S]GTPgammaS binding by 1.9-fold over basal, but its actions were only partially reversed by the selective D2/D3 receptor antagonist, raclopride, indicating the involvement of other receptor subtypes. In contrast, quinelorane-induced stimulation (48% of the effect of dopamine) was abolished by raclopride, and by the D2 receptor antagonist, L741,626. Further, novel antagonists selective for D3 and D4 receptors, S33084 and S18126, respectively, blocked the actions of quinelorane at concentrations corresponding to their affinities for D2 receptors. Quinelorane potently induced contralateral rotation in unilaterally 6-OHDA-lesioned rats, an effect abolished by raclopride and L741,626, but not by D3 and D4 receptor-selective doses of S33084 and S18126, respectively. In functional ([35S]GTPgammaS) autoradiography experiments, quinelorane stimulated G-protein activation in caudate putamen and, to a lesser extent, in nucleus accumbens and cingulate cortex of naive rats. In unilaterally SNPC-lesioned rats, quinelorane-induced G-protein activation in the caudate putamen on the non-lesioned side was similar to that seen in naive animals (approximately 50% stimulation), but significantly greater on the lesioned side (approximately 80%). This increase was both pharmacologically and regionally specific since it was reversed by raclopride, and was not observed in nucleus accumbens or cingulate cortex. In conclusion, the present data indicate that, in rat striatum, the actions of quinelorane are mediated primarily by D2 receptors, and suggest that behavioural hypersensitivity to this agonist, induced by unilateral SNPC lesions, is associated with an increase in D2, but not D3 or D4, receptor-mediated G-protein activation.
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Affiliation(s)
- A Newman-Tancredi
- Department of Psychopharmacology, Institut de Recherches Servier, 125 Chemin de Ronde, 78290 Croissy-sur-Seine, Paris, France.
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Inoue A, Nakata Y. Strategy for modulation of central dopamine transmission based on the partial agonist concept in schizophrenia therapy. JAPANESE JOURNAL OF PHARMACOLOGY 2001; 86:376-80. [PMID: 11569610 DOI: 10.1254/jjp.86.376] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The dopamine system is known to be closely involved in brain neuronal dysfunction and in diseases such as Parkinson's disease, Tourette's syndrome, attention deficit hyperactive disorder, generation of pituitary tumors and schizophrenia. According to the classical dopamine hypothesis on the pathology of schizophrenia, conventional antipsychotics has D2 dopamine receptor antagonistic profiles. However, the use of typical antipsychotics has several limitations; that is, some patients do not respond to them, they can even worsen negative symptoms, and they can provoke unacceptable extrapyramidal and endocrine side effects. To produce effective antipsychotics with reduced side effects, partial agonists to D2 dopamine receptors (D2 receptors) have been developed. Despite the effectiveness of partial agonists for pre- and postsynaptic D2 receptors, administration of such drugs results in inconsistent clinical effects to ameliorate the symptoms of schizophrenia. Thus, strategies for obtaining ideal effective antipsychotics with reduced side effects are considered in this short review with respect to the intrinsic efficacies and affinities of the partial agonists, based on the partial agonist concept.
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Affiliation(s)
- A Inoue
- Department of Pharmacology, Institute of Pharmaceutical Sciences, Hiroshima University School of Medicine, Japan.
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Ahlenius S, Ericson E, Florvall L, Jiménez P, Hillegaart V, Wijkström A. In vivo characterization of novel full and partial 2-(4-aminophenyl)-N,N-dipropylethylamine dopamine D(2) receptor agonists. Eur J Pharmacol 2000; 394:247-53. [PMID: 10771290 DOI: 10.1016/s0014-2999(00)00158-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Behavioral and biochemical techniques were used to compare the in vivo intrinsic efficacy of two new 2-(4-aminophenyl)-N, N-dipropylethylamine dopamine D(2) receptor agonists, 2-(4-amino-3-trifluoromethylphenyl)-N-N-dipropyl-ethylamine (NBF-203) and 2-(4-amino-3-bromo-5-trifluoromethylphenyl)-N-N-dipropylethylamine (NBF-234). Adult male Sprague-Dawley rats were used as experimental animals. NBF-203 was characterized as a full dopamine D(2) receptor agonist, whereas NBF-234 displayed properties of a partial agonist, or antagonist, at dopamine D(2) receptors. Thus, NBF-203 produced effects similar to those of apomorphine in models for dopamine synthesis, release and turnover. As a strong indication of markedly less intrinsic efficacy, the administration of NBF-234 did not result in antagonism of reserpine-induced suppression of locomotor activity in the presence of (+/-)-1-phenyl-2,3,4,5, -tetrahydro-(1H)-3-benzazepine-7,8-diol HCl (SKF-38393)-induced dopamine D(1) receptor activation. The present series of compounds offer the possibility of adjusting intrinsic efficacy at dopamine D(2) receptors, and such fine-tuning could be an important strategy in the search for optimal antipsychotic or antiparkinson drugs within the partial dopamine D(2) receptor agonist concept.
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Affiliation(s)
- S Ahlenius
- Department of Pharmacology, Astra Arcus, SE-151 85, Södertälje, Sweden.
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Discovery and preclinical evaluation of novel dopamine partial agonists as antipsychotic agents. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1067-5698(00)80005-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Witkin J, Gasior M, Acri J, Beekman M, Thurkauf A, Yuan J, DeBoer P, Wikström H, Dijkstra D. Atypical antipsychotic-like effects of the dopamine D3 receptor agonist, (+)-PD 128,907. Eur J Pharmacol 1998; 347:R1-3. [PMID: 9741997 DOI: 10.1016/s0014-2999(98)00174-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Anti-schizophrenia agents with improved efficacy and side-effect profiles are required. A dopamine D3 receptor agonist, R-(+)-trans-3,4a,10b-tetrahydro-4-propyl-2H,5H-[1]benzopyrano[4,3- b]-1,4-oxazin-9-ol HCl ((+)-PD 128,907), displayed an atypical antipsychotic profile comparable to that of clozapine. (+)-PD 128,907 blocked stereotypy produced by dizocilpine (MK-801) at 12-fold lower doses than those affecting apomorphine-induced stereotypes in mice and did not produce catalepsy. These effects of (+)-PD 128,907 were stereospecific and were blocked by a D3 antagonist. These data suggest a role for D3 receptors in antipsychotic drug action.
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Affiliation(s)
- J Witkin
- Drug Development Group, NIDA Addiction Research Center, NIH, Baltimore, MD 21224, USA.
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Abstract
The DA hypothesis of schizophrenia is one of the oldest biological hypotheses of schizophrenia with many revised versions. However, it is unlikely that any single neurotransmitter hypothesis is able to explain the biological basis of such a highly heterogenous disorder as schizophrenia in a satisfactory way. Rather, it is evident that the biological vulnerability factors and the 'acute neurophysiology' of schizophrenic symptoms involve a complex set of imbalances of aberrant connections in neuronal circuits in the brain. Dopamine is likely to be one of the transmitter substances involved, as evidenced by recent neuroimaging studies in neuroleptic-naive schizophrenia. Regardless of whether the DA hypothesis of schizophrenia is true or not, the DA hypothesis of neuroleptic drug action still has a relatively solid basis. The DA D2 receptor blockade remains the best characterized clinically useful mechanism of drug action to alleviate psychotic symptoms. The ongoing and future work on the precise role of DA in schizophrenia should focus on first-episode/admission neuroleptic-naive schizophrenic patients. Such studies represent the best opportunity of finding out specific changes in the dopaminergic pathways and relating them in a meaningful way to various dimensions of psychopathology seen in schizophrenic patients.
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Affiliation(s)
- J Hietala
- Department of Psychiatry, Turku University Central Hospital, Finland
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