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Schwarting RKW, Wöhr M, Engler H, Sungur AÖ, Schedlowski M. Behaviorally conditioned effects of psychoactive drugs in experimental animals: What we have learned from nearly a century of research and what remains to be learned. Neurosci Biobehav Rev 2024; 162:105721. [PMID: 38754716 DOI: 10.1016/j.neubiorev.2024.105721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2024] [Revised: 04/26/2024] [Accepted: 05/10/2024] [Indexed: 05/18/2024]
Abstract
Continuous treatment with drugs is a crucial requirement for managing various clinical conditions, including chronic pain and neuropsychiatric disorders such as depression or schizophrenia. Associative learning processes, i.e. Pavlovian conditioning, can play an important role for the effects of drugs and could open new avenues for optimizing patient treatment. In this narrative literature review, we summarize available data in experimental animals regarding the behaviorally conditioned effects of psychostimulants such as d-amphetamine and cocaine, the dopamine receptor agonist apomorphine, the dopamine receptor antagonist haloperidol, morphine and antidepressant drugs. In each section, the drug under discussion is briefly introduced, followed by a detailed examination of conditioning features, including doses and dosing regimens, characteristics of the conditioning process such as test environments or specific conditioned stimuli, testing and conditioned response characteristics, possible extinction or reconditioning or reversal training, neural mechanisms, and finally, the potential clinical relevance of the research area related to the drug. We focus on key outcomes, delve into methodical issues, identify gaps in current knowledge, and suggest future research directions.
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Affiliation(s)
- Rainer K W Schwarting
- Philipps-University of Marburg, Faculty of Psychology, Experimental and Biological Psychology, Behavioral Neuroscience, Marburg D-35032, Germany; Center for Mind, Brain and Behavior, Marburg D-35032, Germany
| | - Markus Wöhr
- Philipps-University of Marburg, Faculty of Psychology, Experimental and Biological Psychology, Behavioral Neuroscience, Marburg D-35032, Germany; Center for Mind, Brain and Behavior, Marburg D-35032, Germany; KU Leuven, Faculty of Psychology and Educational Sciences, Research Unit Brain and Cognition, Laboratory of Biological Psychology, Social and Affective Neuroscience Research Group, Leuven B-3000, Belgium; KU Leuven, Leuven Brain Institute, Leuven B-3000, Belgium
| | - Harald Engler
- Institute of Medical Psychology and Behavioral Immunobiology, Center for Translational Neuro-, and Behavioral Sciences, University Hospital Essen, University of Duisburg-Essen, Essen D-45147, Germany
| | - A Özge Sungur
- Philipps-University of Marburg, Faculty of Psychology, Experimental and Biological Psychology, Behavioral Neuroscience, Marburg D-35032, Germany; Center for Mind, Brain and Behavior, Marburg D-35032, Germany; KU Leuven, Faculty of Psychology and Educational Sciences, Research Unit Brain and Cognition, Laboratory of Biological Psychology, Social and Affective Neuroscience Research Group, Leuven B-3000, Belgium; KU Leuven, Leuven Brain Institute, Leuven B-3000, Belgium
| | - Manfred Schedlowski
- Institute of Medical Psychology and Behavioral Immunobiology, Center for Translational Neuro-, and Behavioral Sciences, University Hospital Essen, University of Duisburg-Essen, Essen D-45147, Germany; Department of Clinical Neuroscience, Osher Center for Integrative Medicine, Karolinska Institutet, Stockholm 171 77, Sweden
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Ferreira JS, de Mello Bastos JM, Leite Junior JB, Samuels RI, Carey RJ, Carrera MP. Morphine administered post-trial induces potent morphine conditioned effects if the context is novel but not if the context is familiar. Pharmacol Biochem Behav 2020; 196:172978. [PMID: 32593788 DOI: 10.1016/j.pbb.2020.172978] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 06/14/2020] [Accepted: 06/23/2020] [Indexed: 11/18/2022]
Abstract
Morphine administered shortly after exposure to a novel environment induces potent locomotor stimulant conditioning. Environmental novelty is important as pre-exposure (PE) to a stimulus can attenuate the capacity to acquire conditioned stimulus (CS). Here, the importance of environmental novelty for the efficacy of an open-field to become a CS for elicitation of a morphine conditioned response was assessed by comparing the effects of morphine administered post-trial following a 5 min exposure to a novel environment versus a PE environment. Four groups of rats (2 vehicle and 2 morphine groups) were used. Two groups received ten daily 5 min non-drug PEs to an open-field arena and the other two groups were not pre-exposed to the environment. Subsequently, all groups received post-trial injections of either vehicle or morphine immediately after each of five daily 5 min sessions in the open-field. Importantly, on the first day of testing prior to the first post-test morphine administration, the locomotor activity of the novel and PE groups was not different. Over the 5 post-trial morphine treatments, the activity of the PE morphine group, the PE vehicle and the novel environment vehicle groups did not change and were equivalent. In contrast, in the novel environment morphine group, a conditioned hyper-activity response increased with repeated post-trial morphine treatments. For the morphine group it is suggested that the novel environment initiated a post-trial stimulus trace that occurred in temporal contiguity with the post-trial drug response and enabled the trace to become a CS for the morphine unconditioned response. In contrast, PE induced a latent inhibition effect in the PE morphine group, thus the post-trial CS trace was insufficient to become associated to the morphine response and no conditioning occurred. In addition to conventional drug induced Pavlovian delay conditioning, the findings are suggestive of drug induced Pavlovian trace conditioning.
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Affiliation(s)
- Jaise Silva Ferreira
- Behavioral Pharmacology Group, Laboratory of Animal Morphology and Pathology, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes 28013-602, RJ, Brazil
| | - João Marcos de Mello Bastos
- Behavioral Pharmacology Group, Laboratory of Animal Morphology and Pathology, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes 28013-602, RJ, Brazil
| | - Joaquim Barbosa Leite Junior
- Behavioral Pharmacology Group, Laboratory of Animal Morphology and Pathology, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes 28013-602, RJ, Brazil
| | - Richard Ian Samuels
- Department of Entomology and Plant Pathology, State University of North Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ, Brazil
| | - Robert J Carey
- Department of Psychiatry, SUNY Upstate Medical University, 800 Irving Avenue, Syracuse, NY 13210, USA
| | - Marinete Pinheiro Carrera
- Behavioral Pharmacology Group, Laboratory of Animal Morphology and Pathology, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes 28013-602, RJ, Brazil.
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Santillán-Urquiza MA, Herrera-Ruiz M, Zamilpa A, Jiménez-Ferrer E, Román-Ramos R, Alegría-Herrera EY, Tortoriello J. Galphimia glauca and Natural Galphimines Block Schizophrenia-Like Symptoms Induced with Apomorphine and MK-801 in Mice. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2019; 2019:8404258. [PMID: 31428176 PMCID: PMC6679897 DOI: 10.1155/2019/8404258] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 06/07/2019] [Accepted: 06/26/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND Galphimia glauca has been used for many years in Mexican Traditional Medicine to calm "insane people." Triterpenes, known as galphimines, were identified in this species. One of them, Galphimine-B (G-B), acts selectively on dopaminergic neurons by antagonizing the effect of glutamate on NMDA receptors. The objective of this study was to evaluate the effect of G. glauca methanolic extract (GgMeOH), a Galphimine-Rich Fraction (GRF), as well as the galphimines G-A, G-B, and G-E, on the acute psychosis induced by Apomorphine (APO) in mice and on schizophrenia-like symptoms induced by subchronic administration of MK-801. METHOD On the first day, ICR male mice were given GgMeOH, GRF, or one of the galphimines. On day two, animals were treated with APO, and on day 3, they were subjected to behavioral tests. In a second test, MK-801 was administered daily for 28 days. In this case, animals were treated daily with G. glauca products from day 9 to day 28 and then subjected to behavioral tests (passive avoidance test, open field test, forced swimming test, and social interaction test). RESULTS The increased number of stereotyped behaviors and grooming behaviors induced with APO were counteracted by all of the experimental treatments. MK-801 induced an increase in immobility time, which was blocked with G-B; GRF counteracted the decreased social interaction, and GgMeOH and GRF prevented the memory loss induced by MK-801. CONCLUSION G. glauca and their derivatives products (GRF and galphimines) were able to interact with the dopaminergic and glutamatergic drugs and to block different behaviors associated with some of the positive, negative, and cognitive symptoms of induced schizophrenia in mice. It is necessary to continue with this research, in order to identify their mechanism of action.
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Affiliation(s)
- Mayra Alejandra Santillán-Urquiza
- Centro de Investigación Biomédica del Sur, Instituto Mexicano del Seguro Social (IMSS), Argentina 1, 62790 Xochitepec, Morelos, Mexico
| | - Maribel Herrera-Ruiz
- Centro de Investigación Biomédica del Sur, Instituto Mexicano del Seguro Social (IMSS), Argentina 1, 62790 Xochitepec, Morelos, Mexico
| | - Alejandro Zamilpa
- Centro de Investigación Biomédica del Sur, Instituto Mexicano del Seguro Social (IMSS), Argentina 1, 62790 Xochitepec, Morelos, Mexico
| | - Enrique Jiménez-Ferrer
- Centro de Investigación Biomédica del Sur, Instituto Mexicano del Seguro Social (IMSS), Argentina 1, 62790 Xochitepec, Morelos, Mexico
| | - Rubén Román-Ramos
- Laboratorio de Farmacología, División de Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana (UAM), Mexico City, Mexico
| | - Elian Yuritzi Alegría-Herrera
- Centro de Investigación Biomédica del Sur, Instituto Mexicano del Seguro Social (IMSS), Argentina 1, 62790 Xochitepec, Morelos, Mexico
| | - Jaime Tortoriello
- Centro de Investigación Biomédica del Sur, Instituto Mexicano del Seguro Social (IMSS), Argentina 1, 62790 Xochitepec, Morelos, Mexico
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Medial prefrontal cortex ERK and conditioning: Evidence for the association of increased medial prefrontal cortex ERK with the presence/absence of apomorphine conditioned behavior using a unique post-trial conditioning/extinction protocol. Behav Brain Res 2019; 365:56-65. [DOI: 10.1016/j.bbr.2019.02.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 02/05/2019] [Accepted: 02/12/2019] [Indexed: 11/17/2022]
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Oliveira LRD, Santos BGD, de Mello Bastos JM, Samuels RI, Carey RJ, Carrera MP. Morphine administered post-trial can induce potent conditioned morphine effects. Pharmacol Biochem Behav 2019; 179:134-141. [DOI: 10.1016/j.pbb.2019.02.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 01/24/2019] [Accepted: 02/24/2019] [Indexed: 11/24/2022]
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Reversal of morphine conditioned behavior by an anti-dopaminergic post-trial drug treatment during re-consolidation. Behav Brain Res 2019; 359:771-782. [DOI: 10.1016/j.bbr.2018.08.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 07/31/2018] [Accepted: 08/10/2018] [Indexed: 11/30/2022]
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Santos BG, Carey RJ, Carrera MP. Repeated pre-trial and post-trial low and high dose apomorphine treatments induce comparable inhibitory/excitatory sensitization and conditioned drug effects. Pharmacol Biochem Behav 2018; 175:108-115. [DOI: 10.1016/j.pbb.2018.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 09/23/2018] [Accepted: 09/25/2018] [Indexed: 10/28/2022]
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Anselme P, Edeş N, Tabrik S, Güntürkün O. Long-term behavioral sensitization to apomorphine is independent of conditioning and increases conditioned pecking, but not preference, in pigeons. Behav Brain Res 2018; 336:122-134. [DOI: 10.1016/j.bbr.2017.08.037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 08/24/2017] [Accepted: 08/25/2017] [Indexed: 10/19/2022]
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ERK activation in the prefrontal cortex by acute apomorphine and apomorphine conditioned contextual stimuli. Pharmacol Biochem Behav 2017; 159:76-83. [DOI: 10.1016/j.pbb.2017.07.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 06/23/2017] [Accepted: 07/19/2017] [Indexed: 11/17/2022]
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Santos BG, Carey RJ, Carrera MP. The acquisition, extinction and spontaneous recovery of Pavlovian drug conditioning induced by post-trial dopaminergic stimulation/inhibition. Pharmacol Biochem Behav 2017; 156:24-29. [PMID: 28392213 DOI: 10.1016/j.pbb.2017.04.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 02/11/2017] [Accepted: 04/03/2017] [Indexed: 11/18/2022]
Abstract
In contextual drug conditioning, the onset of the drug treatment is contiguous with the contextual cues. Evidence suggests that drug conditioning also can occur if there is a discontinuity between the onset of the drug effect and offset of the contextual cues. Here we examine whether post-trial contextual drug conditioning conforms to several Pavlovian conditioning tenets namely: acquisition, extinction and spontaneous recovery. Six groups of rats received apomorphine (0.05 or 2.0mg/kg) and vehicle immediately or after a 15min delay following a 5min non-drug exposure to an open-field during three successive days (conditioning phase). The extinction phase occurred on days 4-8, in which all post-trial treatments were vehicle injections. After 2days of non-testing, the final test was performed. The results showed that on the first test day, the activity levels of the 6 groups were statistically equivalent. On test day 2, there were marked differences in activity levels selectively between the two immediate post-trial apomorphine treatment groups. The immediate low dose apomorphine group displayed a reduction in activity and the immediate high dose group an increase in activity relative to their day 1 levels. The activity levels of both vehicle groups and both apomorphine delay groups remained equivalent to their day 1 activity levels. On test day 3, the differences in activity levels between the two immediate post-trial apomorphine groups increased but the activity levels of the vehicle groups and the 15min delay post-trial apomorphine groups remained unchanged. In the extinction phase, the conditioned activity differences between the two immediate post-trial apomorphine groups were gradually eliminated. During the final test, the activity differences between the immediate post-trial apomorphine groups were partially restored, indicative of spontaneous recovery. These findings are consistent with several basic elements of Pavlovian conditioning and are supportive of drug induced trace conditioning.
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Affiliation(s)
- Breno Garone Santos
- Behavioral Pharmacology Group, Laboratory of Morphology and Pathology Animal Health, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes 28013-600, RJ, Brazil
| | - Robert J Carey
- Research and Development (151), VA Medical Center and SUNY Upstate Medical University, 800 Irving Avenue, Syracuse, NY 13210, USA
| | - Marinete Pinheiro Carrera
- Behavioral Pharmacology Group, Laboratory of Morphology and Pathology Animal Health, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes 28013-600, RJ, Brazil.
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Inhibition of apomorphine-induced behavioral sensitization in rats pretreated with fluoxetine. Behav Pharmacol 2015; 26:159-66. [PMID: 24755891 DOI: 10.1097/fbp.0000000000000040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Despite a number of clinically useful effects, there is growing evidence that psychosis and impulse control disorders develop in patients on apomorphine therapy. Evidence suggests a critical role of serotonin-1A receptors in psychosis, drug abuse, and in the mechanism of action of the prototypical selective serotonin reuptake inhibitor fluoxetine. We investigated whether fluoxetine can prevent apomorphine-induced behavioral sensitization in a rat model of psychosis. Animals treated with fluoxetine (5 and 10 mg/kg) for 2 weeks were subsequently cotreated with apomorphine (1.0 mg/kg) for 7 days. A single injection of apomorphine increased motor activity, whereas repeated daily injections produced a progressive sensitization of motor behavior. The sensitization effects of apomorphine did not occur in fluoxetine-pretreated and subsequently cotreated animals. To further elucidate the mechanism involved in the inhibition of apomorphine sensitization in fluoxetine-treated animals, we found that apomorphine-induced motor behavior was much greater in repeated apomorphine-treated than repeated saline-treated animals. It was also greater in apomorphine and fluoxetine-cotreated animals, but not in animals pretreated and cotreated with fluoxetine. The mechanism involved in the inhibition of apomorphine sensitization in fluoxetine-pretreated animals is discussed. The findings introduce an innovative approach for extending the therapeutic use of apomorphine and classical psychostimulant drugs.
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Carey RJ, Damianopoulos EN. Serotonin and conditioning: focus on Pavlovian psychostimulant drug conditioning. Behav Brain Res 2015; 282:227-36. [PMID: 25446748 DOI: 10.1016/j.bbr.2014.10.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 10/15/2014] [Accepted: 10/20/2014] [Indexed: 11/27/2022]
Abstract
Serotonin containing neurons are located in nuclei deep in the brainstem and send axons throughout the central nervous system from the spinal cord to the cerebral cortex. The vast scope of these connections and interactions enable serotonin and serotonin analogs to have profound effects upon sensory/motor processes. In that conditioning represents a neuroplastic process that leads to new sensory/motor connections, it is apparent that the serotonin system has the potential for a critical role in conditioning. In this article we review the basics of conditioning as well as the serotonergic system and point up the number of non-associative ways in which manipulations of serotonin neurotransmission have an impact upon conditioning. We focus upon psychostimulant drug conditioning and review the contribution of drug stimuli in the use of serotonin drugs to investigate drug conditioning and the important impact drug stimuli can have on conditioning by introducing new sensory stimuli that can create or mask a CS. We also review the ways in which experimental manipulations of serotonin can disrupt conditioned behavioral effects but not the associative processes in conditioning. In addition, we propose the use of the recently developed memory re-consolidation model of conditioning as an approach to assess the possible role of serotonin in associative processes without the complexities of performance effects related to serotonin treatment induced alterations in sensory/motor systems.
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Affiliation(s)
- Robert J Carey
- Research Service and Development (151), VA Medical Center, 800 Irving Avenue, Syracuse, NY 13210, USA; Department of Psychiatry and Graduate School, SUNY Upstate Medical University at Syracuse, Syracuse, NY, USA.
| | - Ernest N Damianopoulos
- Research Service and Development (151), VA Medical Center, Room 326, 800 Irving Avenue, Syracuse, NY 13210, USA
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A new proposal for drug conditioning with implications for drug addiction: The Pavlovian two-step from delay to trace conditioning. Behav Brain Res 2014; 275:150-6. [DOI: 10.1016/j.bbr.2014.08.053] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 08/24/2014] [Accepted: 08/26/2014] [Indexed: 11/22/2022]
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White AO, Rauhut AS. Time-dependent effects of prazosin on the development of methamphetamine conditioned hyperactivity and context-specific sensitization in mice. Behav Brain Res 2014; 263:80-9. [PMID: 24487011 PMCID: PMC3985165 DOI: 10.1016/j.bbr.2014.01.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 01/17/2014] [Accepted: 01/21/2014] [Indexed: 01/04/2023]
Abstract
The present experiments examined the effects of prazosin, a selective α₁-adrenergic receptor antagonist, on the development of methamphetamine conditioned hyperactivity and context-specific sensitization. Mice received an injection of vehicle (distilled water) or prazosin (0.5, 1.0 or 2.0 mg/kg) 30 min prior to a second injection of vehicle (saline) or methamphetamine (1.0 mg/kg) during the conditioning sessions (Experiment 1). Following the conditioning sessions, mice were tested for conditioned hyperactivity and then tested for context-specific sensitization. In subsequent experiments, mice received an injection of vehicle (distilled water) or prazosin (2.0 mg/kg) immediately (Experiment 2) or 24 h (Experiment 3) after the conditioning sessions and then tested for conditioned hyperactivity and context-specific sensitization. Prazosin dose-dependently blocked the development of methamphetamine conditioned hyperactivity and context-specific sensitization when administered prior to the methamphetamine during the conditioning phase; however nonspecific motor impairments also were observed (Experiment 1). Immediate (Experiment 2), but not the 24-h delay (Experiment 3), post-session administration of prazosin attenuated the development of methamphetamine conditioned hyperactivity and context-specific sensitization. Nonspecific motor impairments were not observed in these latter experiments. Collectively, these results suggest that the α₁-adrenergic receptor mediates the development of methamphetamine-conditioned hyperactivity and context-specific sensitization, perhaps by altering memory consolidation and/or reconsolidation processes.
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Sanguedo FVC, Cruz Dias FR, Bloise E, Cespedes IC, Giraldi-Guimarães A, Samuels RI, Carey RJ, Carrera MP. Increase in medial frontal cortex ERK activation following the induction of apomorphine sensitization. Pharmacol Biochem Behav 2014; 118:60-8. [DOI: 10.1016/j.pbb.2013.12.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/17/2013] [Accepted: 12/22/2013] [Indexed: 10/25/2022]
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de Mello Bastos JM, Dias FRC, Alves VHN, Carey RJ, Carrera MP. Drug memory substitution during re-consolidation: A single inhibitory autoreceptor apomorphine treatment given during psychostimulant memory re-consolidation replaces psychostimulant conditioning with conditioned inhibition and reverses psychostimulant sensitization. Behav Brain Res 2014; 260:139-47. [DOI: 10.1016/j.bbr.2013.11.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 10/31/2013] [Accepted: 11/02/2013] [Indexed: 10/26/2022]
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Dias FRC, de Mello Bastos JM, de Fátima Dos Santos Sampaio M, Carey RJ, Carrera MP. Opposite effects of typical and atypical anti-psychotic drugs on sensitized dopamine receptors: sub-chronic low dose Olanzapine exposure reverses sensitization but a similar regimen of low dose haloperidol potentiates sensitization effects. Psychopharmacology (Berl) 2013; 230:579-88. [PMID: 23846543 DOI: 10.1007/s00213-013-3184-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 06/11/2013] [Indexed: 11/29/2022]
Abstract
RATIONALE Both typical and atypical antipsychotic drugs are D2 receptor antagonists but yet appear to have markedly different effects upon the induction of dopamine sensitization. OBJECTIVE This study aims to compare the effects of subchronic regimens of low-dose olanzapine and haloperidol administered to rats previously sensitized to apomorphine. METHODS Initially, rats received apomorphine (2.0 mg/kg) or vehicle treatments for five consecutive days followed by a conditioning test and an apomorphine challenge test. Next, there was an antipsychotic exposure phase in which three vehicle groups and three apomorphine groups received 10 daily injections of either vehicle, haloperidol (0.03 mg/kg) or olanzapine (0.01 mg/kg). In the final phase, all groups were given a second conditioning test and apomorphine challenge test. RESULTS Apomorphine induced sensitization and conditioning effects. Following haloperidol exposure, apomorphine conditioned and sensitization effects were potentiated but, in contrast, olanzapine exposure eliminated apomorphine sensitization effects. In addition, the sensitization induced by apomorphine transformed the low-dose haloperidol treatment into a potent locomotor stimulant treatment. In the vehicle groups, haloperidol and olanzapine exposure effects were equivalent and not different from vehicle treatment. CONCLUSIONS The profound differences observed between typical and atypical antipsychotic exposure in animals with an upregulated dopamine system are consistent with clinical evidence for lower risk of psychomotor disturbances with chronic treatment with atypical antipsychotic. Importantly, the finding that a very low dose of olanzapine reversed sensitization effects suggests that low-dose olanzapine may have clinical utility in a variety of disorders linked to sensitization of the dopamine system.
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Affiliation(s)
- Flávia Regina Cruz Dias
- Behavioral Pharmacology Group, Laboratory of Animal Morphology and Pathology Animal, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes, 28013-602, RJ, Brazil
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Haleem DJ, Ikram H, Haider S, Parveen T, Haleem MA. Enhancement and inhibition of apomorphine-induced sensitization in rats exposed to immobilization stress: Relationship with adaptation to stress. Pharmacol Biochem Behav 2013; 112:22-8. [DOI: 10.1016/j.pbb.2013.09.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 09/06/2013] [Accepted: 09/22/2013] [Indexed: 10/26/2022]
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Haleem DJ. Extending therapeutic use of psychostimulants: focus on serotonin-1A receptor. Prog Neuropsychopharmacol Biol Psychiatry 2013; 46:170-80. [PMID: 23906987 DOI: 10.1016/j.pnpbp.2013.07.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Revised: 07/02/2013] [Accepted: 07/16/2013] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Despite a number of medicinally important pharmacological effects, the therapeutic use of psychostimulants is limited because of abuse potential and psychosis following long term use. Development of pharmacological agents for improving and extending therapeutic use of psychostimulants in narcolepsy, attention deficit hyperactivity disorder, Parkinson's disease, obesity and as cognitive enhancer is an important research imperative. In this regard, one potential target system is the 5-hydroxytryptamine (5-HT; serotonin) neurotransmitter system. The focus of the present article is to evaluate a potential role of 5-HT-1A receptor in the alleviation of abuse potential and psychosis-induced by prescription psychostimulants amphetamines and apomorphine. METHOD Synaptic contacts between dopamine systems and 5-HT-1A receptors are traced. Studies on serotonin-1A influences on the modulation of dopamine neurotransmission and psychostimulant-induced behavioral sensitization are accumulated. RESULTS Inhibition of amphetamine and apomorphine-induced behavioral sensitization by co administration of 5-HT-1A agonists cannot be explained in terms of direct activation of 5-HT-1A receptors, because activation of pre- as well as postsynaptic 5-HT-1A receptors tends to increase dopamine neurotransmission. CONCLUSION Long term use of amphetamine and apomorphine produces adaptive changes in 5-HT-1A receptor mediated functions, which are prevented by the co-use of 5-HT-1A agonists. In view of extending medicinal use of psychostimulants, it is important to evaluate the effects of co-use of 5-HT-1A agonists on potential therapeutic profile of amphetamine and apomorphine in preclinical research. It is also important to evaluate the functional significance of 5-HT-1A receptors on psychostimulant-induced behaviors in other addiction models such as drug self-administration and reinstatement of drug seeking behavior.
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Affiliation(s)
- Darakhshan Jabeen Haleem
- Neuroscience Research Laboratory, Dr Panjwani Center for Molecular Medicine & Drug Research (PCMD), International Center for Chemical and Biological Science (ICCBS), University of Karachi, Karachi 75270, Pakistan.
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Davis-MacNevin PL, Dekraker J, LaDouceur L, Holahan MR. Comparison of the MK-801-induced increase in non-rewarded appetitive responding with dopamine agonists and locomotor activity in rats. J Psychopharmacol 2013; 27:854-64. [PMID: 23761388 DOI: 10.1177/0269881113492029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Systemic administration of the noncompetitive N-methyl-D-aspartate (NMDA)- receptor antagonist, MK-801, has been proposed to model cognitive deficits similar to those seen in patients with schizophrenia. Evidence has shown that MK-801 increases the probability of operant responding during extinction, possibly modeling perseveration, as would be seen in patients with schizophrenia. This MK-801-induced behavioral perseveration is reversed by dopamine receptor antagonism. To further explore the role of dopamine in this behavioral change, the current study sought to determine if the MK-801-induced increase in non-rewarded operant responding could be mimicked by dopamine agonism and determine how it was related to locomotor activity. Male Long Evans rats were treated systemically with MK-801, cocaine, GBR12909 or apomorphine (APO) and given a single trial operant extinction session, followed by a separate assessment of locomotor activity. Both MK-801 (0.05 mg/kg) and cocaine (10 mg/kg) significantly increased responding during the extinction session and both increased horizontal locomotor activity. No dose of GBR-12909 (5, 10 or 20 mg/kg) was found to effect non-rewarded operant responding or locomotor activity. APO (0.05, 0.5, 2 or 5 mg/kg) treatment produced a dose-dependent decrease in both operant responding and locomotor activity. These results suggest the possibility that, rather than a primary influence of increased dopamine concentration on elevating bar-pressing responses during extinction, other neurotransmitter systems may be involved.
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Dias FRC, de Matos LW, Dos Santos Sampaio MDF, Carey RJ, Carrera MP. Residual dopamine receptor desensitization following either high- or low-dose sub-chronic prior exposure to the atypical anti-psychotic drug olanzapine. Psychopharmacology (Berl) 2013; 225:141-50. [PMID: 22825579 DOI: 10.1007/s00213-012-2802-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 07/02/2012] [Indexed: 10/28/2022]
Abstract
RATIONALE Anti-psychotic drugs are antagonists of dopamine D2 receptors and repeated administration may lead to the development of dopamine receptor supersensitivity. OBJECTIVES The objective of this study is to investigate the effects of sub-chronic olanzapine treatments upon the induction of dopamine receptor supersensitivity. METHODS Rats were administered ten daily low or high doses of the atypical anti-psychotic drug olanzapine (0.01 or 1.0 mg/kg). After 5 days of withdrawal, all groups received 2.0 mg/kg apomorphine on five successive days. Five days after the apomorphine sensitization protocol, in separate experiments, either a conditioning test or an apomorphine sensitization test was conducted. RESULTS During the anti-psychotic treatment the high dose of olanzapine induced profound locomotion suppression, whereas the low dose had no effect upon locomotion. The apomorphine treatments given to the vehicle control group generated locomotor sensitization. This sensitization effect was attenuated by the same degree for both the low or high dose prior olanzapine treatments. Also, the low and high-dose olanzapine pre-treatments diminished subsequent apomorphine-conditioned and apomorphine-sensitized locomotor responses. CONCLUSIONS The equivalent attenuation of the apomorphine sensitization produced by both olanzapine doses indicates that this effect was unrelated to the direct effects of olanzapine upon locomotion. Furthermore, the persistence of the desensitization effects well after the termination of the olanzapine treatments is indicative of a residual desensitization of the dopamine system. These findings are of importance when considering the use of atypical anti-psychotic drugs in the treatment of psychoses and other disorders in which overactivity of the dopamine system is considered a contributory factor.
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Affiliation(s)
- Flávia Regina Cruz Dias
- Behavioral Pharmacology Group, Laboratory of Animal Morphology and Pathology, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes, 28013-602 Rio de Janeiro, Brazil
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Post-trial apomorphine at an autoreceptor dose level can eliminate apomorphine conditioning and sensitization: Support for the critical role of dopamine in re-consolidation. Behav Brain Res 2013; 236:244-250. [DOI: 10.1016/j.bbr.2012.06.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 06/22/2012] [Accepted: 06/23/2012] [Indexed: 11/23/2022]
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Ratajczak P, Kus K, Jarmuszkiewicz Z, Woźniak A, Cichocki M, Nowakowska E. Influence of aripiprazole and olanzapine on behavioral dysfunctions of adolescent rats exposed to stress in perinatal period. Pharmacol Rep 2013; 65:30-43. [DOI: 10.1016/s1734-1140(13)70961-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 09/28/2012] [Indexed: 01/12/2023]
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Carrera MP, Carey RJ, Dias FRC, de Mattos LW. Memory re-consolidation and drug conditioning: an apomorphine conditioned locomotor stimulant response can be enhanced or reversed by a single high versus low apomorphine post-trial treatment. Psychopharmacology (Berl) 2012; 220:281-91. [PMID: 21922172 DOI: 10.1007/s00213-011-2474-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 08/30/2011] [Indexed: 11/28/2022]
Abstract
RATIONALE Psychostimulant sensitization can have transformative effects upon contextual stimuli such as acquired conditioned stimuli and conditioned incentive motivational properties. OBJECTIVE The aim of this study is to induce apomorphine sensitization and conduct non-drug exposures to the contextual cues followed by post-trial treatments designed to associate increases/decreases in dopamine activity with re-consolidation of the contextual cue conditioned stimulus. METHODS Separate groups received five daily apomorphine (2.0 mg/kg) treatments, paired or unpaired to the test environment. Two days later, a 30-min non-drug conditioning test was performed. Subsequently, there were three brief (5 min) conditioning tests on successive days. After removal from the test environment on the three test days, all groups received post-trial treatment with vehicle, 0.05, and 2.0 mg/kg apomorphine. One day later, a second 30-min conditioning test was conducted. RESULTS There was a sensitized and a conditioned locomotor stimulant response in the paired groups. After the first and second post-trial treatments with 0.05 mg/kg apomorphine, the conditioned stimulant response in the paired group was transformed into a conditioned inhibitory response. In contrast, the conditioned stimulant response of the paired group administered with apomorphine 2.0 mg/kg post-trial was amplified. The apomorphine post-trial treatments administered to the unpaired groups or 2 h post-trial to paired groups were without effect. CONCLUSIONS These findings suggest that sensitization substantially enhances the associative sensitivity of contextual stimuli and imply that brief exposure to cues linked to drugs of addiction followed by treatments that inhibit neurotransmitter systems may provide a new direction in drug abuse treatment.
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Affiliation(s)
- Marinete Pinheiro Carrera
- Behavioral Pharmacology Group, Laboratory of Morphology and Pathology Animal Health, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes, 28013-600, RJ, Brazil.
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Dias FRC, de Matos LW, Sampaio MDFDS, Carey RJ, Carrera MP. Opposite effects of low versus high dose haloperidol treatments on spontaneous and apomorphine induced motor behavior: evidence that at a very low dose haloperidol acts as an indirect dopamine agonist. Behav Brain Res 2012; 229:153-9. [PMID: 22244923 DOI: 10.1016/j.bbr.2011.12.042] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2011] [Revised: 12/28/2011] [Accepted: 12/30/2011] [Indexed: 10/14/2022]
Abstract
Anti-psychotic drugs are antagonists at the dopamine D2 receptors and repeated administration can lead to the development of dopamine receptor supersensitivity. In two experiments, separate groups of rats were administered 10 daily low or high doses of the typical anti-psychotic drug haloperidol (0.03 or 1.0 mg/kg). The high dose decreased locomotion whereas, the low dose increased locomotion. After 5 days of withdrawal, all groups received 2.0 mg/kg apomorphine on 5 successive days. The apomorphine treatments given to the vehicle group generated a progressive locomotion sensitization effect and this effect was potentiated by pre-exposure to 0.03 mg/kg haloperidol. Initially, the prior high dose of haloperidol exaggerated the apomorphine locomotor stimulant effect but with repeated apomorphine treatments desensitization developed. Following a 5-day withdrawal period an apomorphine challenge test was conducted and apomorphine sensitization was absent in the haloperidol high dose pre-exposure group but potentiated in the low dose pre-exposure group. In the second replication experiment a conditioning test instead of a sensitization challenge test was conducted 5 days after completion of the 5-day apomorphine treatment protocol. The repeated apomorphine treatments induced conditioned hyper- locomotion and this conditioned effect was prevented by the prior high dose haloperidol pre-exposure but enhanced by the prior low dose haloperidol pre-exposure. Two new key findings are (a) that a low dose haloperidol regimen can function as a dopamine agonist and these effects persist after withdrawal and (b) that repeated apomorphine treatments can desensitize D2 receptors previously sensitized by a high dose haloperidol treatment regimen.
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Affiliation(s)
- Flávia Regina Cruz Dias
- Behavioral Pharmacology Group, Laboratory of Animal Morphology and Pathology, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes, 28013-602, RJ, Brazil
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Ikram H, Haleem DJ. Attenuation of apomorphine-induced sensitization by buspirone. Pharmacol Biochem Behav 2011; 99:444-50. [DOI: 10.1016/j.pbb.2011.04.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 04/07/2011] [Accepted: 04/10/2011] [Indexed: 11/28/2022]
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Apomorphine locomotor sensitization can be potentiated by environmental change: Evidence for a non-Pavlovian associative behavioral contrast factor in sensitization expression. Behav Brain Res 2011; 220:146-51. [DOI: 10.1016/j.bbr.2011.01.049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 01/27/2011] [Accepted: 01/28/2011] [Indexed: 11/24/2022]
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Carrera MP, Carey RJ, Dias FRC, de Matos LW. Reversal of apomorphine locomotor sensitization by a single post-conditioning trial treatment with a low autoreceptor dose of apomorphine: a memory re-consolidation approach. Pharmacol Biochem Behav 2011; 99:29-34. [PMID: 21447355 DOI: 10.1016/j.pbb.2011.03.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 03/09/2011] [Accepted: 03/22/2011] [Indexed: 11/17/2022]
Abstract
Sensitization is a common feature of psychostimulants and sensitization effects are generally considered to be linked to the addictive properties of these drugs. We used a conventional paired/unpaired Pavlovian protocol to induce a context specific sensitization to the locomotor stimulant effect of a high dose of apomorphine (2.0mg/kg). Two days following a 5 session sensitization induction phase, a brief 5min non-drug test for conditioning was conducted. Only the paired groups exhibited locomotor stimulant conditioned response effects. Immediately following this brief test for conditioning, the paired and the unpaired groups received injections of 0.05mg/kg apomorphine, 2.0mg/kg apomorphine or vehicle designed to differentially impact memory re-consolidation of the conditioning. Two days later, all groups received a sensitization challenge test with 2.0mg/kg apomorphine. The 2.0mg/kg apomorphine post-trial treatment potentiated sensitization while the 0.05mg/kg eliminated sensitization. These effects were only observed in the paired groups. The activation of dopaminergic systems by the high dose of apomorphine strengthened the drug/environment association whereas the inhibition of dopamine activity by the low auto-receptor dose eliminated this association. The results point to the importance of conditioning to context specific sensitization and targeting memory re-consolidation of conditioning as a paradigm to modify sensitization.
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Affiliation(s)
- Marinete Pinheiro Carrera
- Behavioral Pharmacology Group, Laboratory of Animal Morphology and Pathology, State University of North Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, Campos dos Goytacazes, 28013-600, RJ, Brazil.
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Lane EL, Daly CS, Smith GA, Dunnett SB. Context-driven changes in L-DOPA-induced behaviours in the 6-OHDA lesioned rat. Neurobiol Dis 2011; 42:99-107. [PMID: 21220017 DOI: 10.1016/j.nbd.2011.01.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 12/07/2010] [Accepted: 01/02/2011] [Indexed: 10/18/2022] Open
Abstract
Both contralateral rotational behaviour and dyskinetic abnormal involuntary movements (AIMs) are induced by the administration of l-DOPA in the unilateral 6-OHDA lesioned rat model of Parkinson's disease. Since rotational responses can be conditioned to environmental cues we have investigated the extent to which drug-induced AIMS may also be conditioned by exteroceptive cues and experience. In Experiment I, 6-OHDA lesioned rats received repeated daily injections of l-DOPA either in their home cage (control) or in association with a brief (20 mins) exposure to the rotometers (paired). To assess conditioning, all animals then received two tests in the rotometer bowls. Following injection of saline the paired group both rotated more contralaterally and displayed manifest AIMs, neither of which were exhibited by the control rats. Moreover, following injection of l-DOPA, the paired group showed a trend for increased AIMs compared to controls. Two further studies provided longer exposure to the conditioning environments in counterbalanced designs. Although, using these parameters, re-exposure in the presence of saline did not induce context-dependent AIMs, a strong context-specific component of the sensitised response to l-DOPA was seen; chronic administration of drug produced a significantly stronger behavioural response in animals paired with a particular environment for drug administration than controls. This data suggests that part of the sensitisation of behavioural responding to l-DOPA administration is not solely a pharmacological phenomenon, but is also conditioned to the environmental context in which the drug is administered. This has clear implications for the clinical observation and experimental measurement of drug-induced dyskinesia in Parkinson's disease patients and animal models.
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Affiliation(s)
- E L Lane
- Brain Repair Group, School of Biosciences, Cardiff University, Cardiff, Wales, CF10 3AX, UK.
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de Matos LW, Carey RJ, Carrera MP. Apomorphine conditioning and sensitization: The paired/unpaired treatment order as a new major determinant of drug conditioned and sensitization effects. Pharmacol Biochem Behav 2010; 96:317-24. [DOI: 10.1016/j.pbb.2010.05.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 05/14/2010] [Accepted: 05/23/2010] [Indexed: 11/15/2022]
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Dias FRC, Carey RJ, Carrera MP. Apomorphine-induced context-specific behavioural sensitization is prevented by the D1 antagonist SCH-23390 but potentiated and uncoupled from contextual cues by the D2 antagonist sulpiride. Psychopharmacology (Berl) 2010; 209:137-51. [PMID: 20177884 DOI: 10.1007/s00213-009-1768-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 12/20/2009] [Indexed: 11/24/2022]
Abstract
RATIONALE In the study of behavioural sensitization induced by dopamine agonists, D1 and D2 receptors have a critical, but a puzzling role. OBJECTIVE The objective of this study is to examine the effects of the D1 antagonist SCH-23390 and the D2 antagonist sulpiride given repeatedly alone or in combination with apomorphine upon apomorphine conditioning and sensitization. METHODS Apomorphine-induced (2.0 mg/kg) conditioning and sensitization were assessed following five paired/unpaired treatments. Sulpiride (10, 30 and 100 mg/kg) and SCH-23390 (0.01, 0.02 and 0.05 mg/kg) were administered alone or in combination with apomorphine. In experiment 1, the effect of 5 days of sulpiride and SCH-23390 treatments given alone were assessed on apomorphine reactivity. In experiment 2, sulpiride and SCH-23390 were co-administered with apomorphine for 5 days and subsequently, conditioning and sensitization tests were performed. In experiment 3, following five apomorphine treatment sessions, sulpiride and SCH-23390 were administered prior to the conditioning and sensitization tests. RESULTS SCH-23390 and sulpiride induced hyper-reactivity to apomorphine. SCH-23390 when given after the induction of apomorphine sensitization, blocked the expression of apomorphine sensitization. When given in combination with apomorphine, SCH-23390 blocked the apomorphine conditioning and sensitization, whereas low-dose sulpiride permitted conditioning and enhanced apomorphine sensitization and high-dose sulpiride blocked conditioning but permitted apomorphine sensitization. Both sulpiride doses transformed apomorphine sensitization from context-specific to context-independent sensitization. CONCLUSION The SCH-23390 findings are supportive of a critical role for D1 receptors in apomorphine effects whereas the sulpiride effects diminish the importance of conditioning and dopamine autoreceptor subsensitivity mechanisms in the mediation of apomorphine sensitization.
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Affiliation(s)
- Flávia Regina Cruz Dias
- Behavioural Pharmacology Group, Laboratory of Animal Health, State University of North Fluminense, Avenida Alberto Lamego, 2000, Campos dos Goytacazes, 28013-600, RJ, Brazil
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