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Ventral tegmental area GABAergic inhibition of cholinergic interneurons in the ventral nucleus accumbens shell promotes reward reinforcement. Nat Neurosci 2021; 24:1414-1428. [PMID: 34385700 PMCID: PMC8823543 DOI: 10.1038/s41593-021-00898-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 06/24/2021] [Indexed: 02/07/2023]
Abstract
The long-range GABAergic input from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) is relatively understudied, and therefore its role in reward processing has remained unknown. In the present study, we show, in both male and female mice, that long-range GABAergic projections from the VTA to the ventral NAc shell, but not to the dorsal NAc shell or NAc core, are engaged in reward and reinforcement behavior. We show that this GABAergic projection exclusively synapses on to cholinergic interneurons (CINs) in the ventral NAc shell, thereby serving a specialized function in modulating reinforced reward behavior through the inhibition of ventral NAc shell CINs. These findings highlight the diversity in the structural and functional topography of VTA GABAergic projections, and their neuromodulatory interactions across the dorsoventral gradient of the NAc shell. They also further our understanding of neuronal circuits that are directly implicated in neuropsychiatric conditions such as depression and addiction.
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2
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Assari S, Boyce S, Bazargan M. Nucleus Accumbens Functional Connectivity with the Frontoparietal Network Predicts Subsequent Change in Body Mass Index for American Children. Brain Sci 2020; 10:brainsci10100703. [PMID: 33022949 PMCID: PMC7600639 DOI: 10.3390/brainsci10100703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 10/02/2020] [Indexed: 12/18/2022] Open
Abstract
Background: Nucleus accumbens (NAc) is a brain structure with a well-established role in the brain reward processing system. Altered function of the NAc is shown to have a role in the development of food addiction and obesity. However, less is known about sex differences in the role of NAc function as a predictor of children’s change in body mass index (BMI) over time. Aim: We used the Adolescent Brain Cognitive Development data (version 2.01) to investigate sex differences in the predictive role of the NAc functional connectivity with the frontoparietal network on children’s BMI change over a one-year follow-up period. Methods: This 1-year longitudinal study successfully followed 3784 9–10-year-old children. Regression models were used to analyze the data. The predictor variable was NAc functional connectivity with the frontoparietal network measured using resting-state functional magnetic resonance imaging (fMRI). The primary outcome was BMI at the end of the 1-year follow up. Covariates included race, ethnicity, age, socioeconomic factors, and baseline BMI. Sex was the effect modifier. Results: NAc functional connectivity with the frontoparietal network was predictive of BMI changes over time. This association remained significant above and beyond all covariates. The above association, however, was only significant in female, not male children. Conclusion: The epidemiological observation that NAc functional connectivity is associated with BMI changes in children is an extension of well-controlled laboratory studies that have established the role of the NAc in the brain reward processing. More research is needed on sex differences in the brain regions that contribute to childhood obesity.
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Affiliation(s)
- Shervin Assari
- Department of Family Medicine, Charles Drew University, Los Angeles, CA 90059, USA;
- Department of Urban Public Health, Charles Drew University, Los Angeles, CA 90059, USA
- Correspondence: ; Tel.: +(734)-232-0445; Fax: +734-615-8739
| | - Shanika Boyce
- Department of Pediatrics, Charles Drew University, Los Angeles, CA 90059, USA;
| | - Mohsen Bazargan
- Department of Family Medicine, Charles Drew University, Los Angeles, CA 90059, USA;
- Department of Family Medicine, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
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3
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Assari S. Parental Education and Nucleus Accumbens Response to Reward Anticipation: Minorities' Diminished Returns. ACTA ACUST UNITED AC 2020; 2:132-153. [PMID: 34308362 DOI: 10.22158/assc.v2n4p132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Background Considerable research has documented the effects of race and socioeconomic status (SES) on reward-seeking behaviors; however, less is known about the multiplicative effects of race and family SES on brain response to reward anticipation. Marginalization-related Diminished Returns (MDRs) suggest that family SES would show weaker effects on brain development of children in non-White families than in White families. Objective To test race by SES variation in Nucleus Accumbens (NAcc) response to reward anticipation (NAcc-RA) among American children. Methods For this cross-sectional analysis, data came from the Adolescent Brain Cognitive Development (ABCD) study which included 6,419, 9-10 year old children. The independent variable was parental education. The moderator was race. The primary outcome was the right NAcc-RA. Age, sex, ethnicity, household income, and family structure were the covariates. We used mixed effects regression models that adjusted for the nested nature of the ABCD data. Results While high parental education was associated with a higher amount of right NAcc-RA, this effect was stronger for White than non-White children. This finding was evident in the observed interactions between race and parental education on the right NAcc-RA. Discussion For American children, NAcc-RA is not shaped by race or family SES, but by their intersection. As a result of the interaction between race and SES (diminished return of SES for non-Whites), middle-class racial minority children may remain susceptible to high-risk behaviors. Disparities in high-risk behaviors in children should not be reduced to economic disparities. Structural inequalities may reduce the return of SES resources for non-White families.
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Affiliation(s)
- Shervin Assari
- Department of Family Medicine, Charles Drew University, Los Angeles, CA 90059, USA.,Department of Urban Public Health, Charles Drew University, Los Angeles, CA 90059, USA
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4
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Myslivecek J, Farar V, Valuskova P. M(4) muscarinic receptors and locomotor activity regulation. Physiol Res 2018; 66:S443-S455. [PMID: 29355372 DOI: 10.33549/physiolres.933796] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
M(4) muscarinic receptors (M(4) MR) represent a subfamily of G-protein coupled receptors serving a substantial role in spontaneous locomotor activity regulation, cognition and modulation of cholinergic system. With increasing body of literature discussing the role of M(4) MR some controversies arose. Thus, we try here to summarize the current evidence regarding the M(4) MR, with the special focus on their role in Locomotor activity control. We review the molecular function of M(4) MR in specific brain areas implicated in locomotor regulation, and shortly in other CNS processes that could be connected to locomotor activity. We also focus on brain areas implicated in locomotor activity biorhythm changes like suprachiasmatic nucleus, subparaventricular zone posterior hypothalamic area, striatum and thalamus. Gender-related aspects and differences in locomotor activity in males and females are discussed further.
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Affiliation(s)
- J Myslivecek
- Institute of Physiology, First Faculty of Medicine, Charles University, Prague, Czech Republic.
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5
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Klawonn AM, Wilhelms DB, Lindström SH, Singh AK, Jaarola M, Wess J, Fritz M, Engblom D. Muscarinic M4 Receptors on Cholinergic and Dopamine D1 Receptor-Expressing Neurons Have Opposing Functionality for Positive Reinforcement and Influence Impulsivity. Front Mol Neurosci 2018; 11:139. [PMID: 29740282 PMCID: PMC5928231 DOI: 10.3389/fnmol.2018.00139] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 04/05/2018] [Indexed: 12/02/2022] Open
Abstract
The neurotransmitter acetylcholine has been implicated in reward learning and drug addiction. However, the roles of the various cholinergic receptor subtypes on different neuron populations remain elusive. Here we study the function of muscarinic M4 receptors (M4Rs) in dopamine D1 receptor (D1R) expressing neurons and cholinergic neurons (expressing choline acetyltransferase; ChAT), during various reward-enforced behaviors and in a “waiting”-impulsivity test. We applied cell-type-specific gene deletions targeting M4Rs in D1RCre or ChATCre mice. Mice lacking M4Rs in D1R-neurons displayed greater cocaine seeking and drug-primed reinstatement than their littermate controls in a Pavlovian conditioned place preference (CPP) paradigm. Furthermore, the M4R-D1RCre mice initiated significantly more premature responses (PRs) in the 5-choice-serial-reaction-time-task (5CSRTT) than their littermate controls, indicating impaired waiting impulse control. In contrast, mice lacking M4Rs in cholinergic neurons did not acquire cocaine Pavlovian conditioning. The M4R-ChATCre mice were also unable to learn positive reinforcement to either natural reward or cocaine in an operant runway paradigm. Immediate early gene (IEG) expression (cFos and FosB) induced by repeated cocaine injections was significantly increased in the forebrain of M4R-D1RCre mice, whereas it remained normal in the M4R-ChATCre mice. Our study illustrates that muscarinic M4Rs on specific neural populations, either cholinergic or D1R-expressing, are pivotal for learning processes related to both natural reward and drugs of abuse, with opposing functionality. Furthermore, we found that neurons expressing both M4Rs and D1Rs are important for signaling impulse control.
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Affiliation(s)
- Anna M Klawonn
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.,Department of Psychiatry and Behavioural Sciences, Stanford University, Stanford, CA, United States
| | - Daniel B Wilhelms
- Department of Medical and Health Science, Linköping University, Linköping, Sweden.,Department of Emergency Medicine, Linköping University Hospital, Linköping, Sweden
| | - Sarah H Lindström
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Anand Kumar Singh
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Maarit Jaarola
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Jürgen Wess
- Molecular Signaling Section, National Institute of Health, Bethesda, MD, United States
| | - Michael Fritz
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden.,Department of Psychiatry and Behavioural Sciences, Stanford University, Stanford, CA, United States
| | - David Engblom
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
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6
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Mateo Y, Johnson KA, Covey DP, Atwood BK, Wang HL, Zhang S, Gildish I, Cachope R, Bellocchio L, Guzmán M, Morales M, Cheer JF, Lovinger DM. Endocannabinoid Actions on Cortical Terminals Orchestrate Local Modulation of Dopamine Release in the Nucleus Accumbens. Neuron 2017; 96:1112-1126.e5. [PMID: 29216450 DOI: 10.1016/j.neuron.2017.11.012] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 04/08/2017] [Accepted: 11/09/2017] [Indexed: 12/14/2022]
Abstract
Dopamine (DA) transmission mediates numerous aspects of behavior. Although DA release is strongly linked to firing of DA neurons, recent developments indicate the importance of presynaptic modulation at striatal dopaminergic terminals. The endocannabinoid (eCB) system regulates DA release and is a canonical gatekeeper of goal-directed behavior. Here we report that extracellular DA increases induced by selective optogenetic activation of cholinergic neurons in the nucleus accumbens (NAc) are inhibited by CB1 agonists and eCBs. This modulation requires CB1 receptors on cortical glutamatergic afferents. Dopamine increases driven by optogenetic activation of prefrontal cortex (PFC) terminals in the NAc are similarly modulated by activation of these CB1 receptors. We further demonstrate that this same population of CB1 receptors modulates optical self-stimulation sustained by activation of PFC afferents in the NAc. These results establish local eCB actions on PFC terminals within the NAc that inhibit mesolimbic DA release and constrain reward-driven behavior.
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Affiliation(s)
- Yolanda Mateo
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Rockville, MD, USA
| | - Kari A Johnson
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Rockville, MD, USA
| | - Dan P Covey
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Brady K Atwood
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Rockville, MD, USA
| | - Hui-Ling Wang
- Neuronal Networks Section, National Institute on Drug Abuse, US National Institutes of Health, Baltimore, MD, USA
| | - Shiliang Zhang
- Neuronal Networks Section, National Institute on Drug Abuse, US National Institutes of Health, Baltimore, MD, USA
| | - Iness Gildish
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Roger Cachope
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Luigi Bellocchio
- Department of Biochemistry and Molecular Biology I, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS) and Instituto Universitario de Investigación Neuroquímica (IUIN), Complutense University, Madrid, Spain
| | - Manuel Guzmán
- Department of Biochemistry and Molecular Biology I, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS) and Instituto Universitario de Investigación Neuroquímica (IUIN), Complutense University, Madrid, Spain
| | - Marisela Morales
- Neuronal Networks Section, National Institute on Drug Abuse, US National Institutes of Health, Baltimore, MD, USA
| | - Joseph F Cheer
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - David M Lovinger
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Rockville, MD, USA.
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7
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Bregolin T, Pinheiro BS, El Rawas R, Zernig G. Preventive Strength of Dyadic Social Interaction against Reacquisition/Reexpression of Cocaine Conditioned Place Preference. Front Behav Neurosci 2017; 11:225. [PMID: 29167636 PMCID: PMC5682322 DOI: 10.3389/fnbeh.2017.00225] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 10/27/2017] [Indexed: 11/15/2022] Open
Abstract
The reorientation away from drugs of abuse and toward social interaction is a highly desirable but as yet elusive goal in the therapy of substance dependence. We could previously show that cocaine preferring Sprague-Dawley rats which engaged in only four 15 min episodes of dyadic social interaction (DSI) did not reacquire and reexpress cocaine conditioned place preference (CPP) after a single cocaine exposure. In the present study, we investigated how strong this preventive effect of DSI is. In corroboration of our previous findings in rats, four 15 min DSI episodes prevented the reacquisition/reexpression of cocaine CPP in mice. However, this effect was only observed if only one cocaine conditioning session (15 min) was used. If mice were counterconditioned with a total of four cocaine sessions, the cocaine CPP reemerged. Interestingly, the opposite also held true: in mice that had acquired/expressed cocaine CPP, one conditioning session with DSI did not prevent the persistence of cocaine CPP, whereas four DSI conditioning sessions reversed CPP for 15 mg/kg intraperitoneal cocaine. Of note, this cocaine dose was a strong reward in C57BL/6J mice, causing CPP in all tested animals. Our findings suggest that both the reversal (reconditioning) of CPP from cocaine to DSI as well as that from DSI to cocaine requires four conditioning sessions. As previously shown in C57BL/6 mice from the NIH substrain, mice from the Jackson substrain also showed a greater relative preference for 15 mg/kg intraperitoneal cocaine over DSI, whereas Sprague-Dawley rats were equally attracted to contextual stimuli associated with this cocaine dose and DSI. Also in corroboration of previous findings, both C57BL/6J mice and experimenters several generations removed from the original ones produced CPP for DSI to a lesser degree than Sprague-Dawley rats. Our findings demonstrate the robustness of our experimental model across several subject- and experimenter generations in two rodent genus (i.e., mouse and rat) and allow the quantification of the strength (i.e., persistence) of the preventive effect of DSI against the reacquisition/reexpression of cocaine CPP, arguably a model for cocaine relapse.
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Affiliation(s)
- Tanja Bregolin
- Experimental Psychiatry Unit, Department of Psychiatry 1, Medical University of Innsbruck (MUI), Innsbruck, Austria
| | - Barbara S. Pinheiro
- Experimental Psychiatry Unit, Department of Psychiatry 1, Medical University of Innsbruck (MUI), Innsbruck, Austria
| | - Rana El Rawas
- Experimental Psychiatry Unit, Department of Psychiatry 1, Medical University of Innsbruck (MUI), Innsbruck, Austria
| | - Gerald Zernig
- Experimental Psychiatry Unit, Department of Psychiatry 1, Medical University of Innsbruck (MUI), Innsbruck, Austria
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8
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α6β2 subunit containing nicotinic acetylcholine receptors exert opposing actions on rapid dopamine signaling in the nucleus accumbens of rats with high-versus low-response to novelty. Neuropharmacology 2017; 126:281-291. [PMID: 28666811 DOI: 10.1016/j.neuropharm.2017.06.028] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 06/07/2017] [Accepted: 06/26/2017] [Indexed: 11/22/2022]
Abstract
Determining neurobiological factors that contribute to individual variance in drug addiction vulnerability allows for identification of at-risk populations, use of preventative measures and personalized medicine in the treatment of substance use disorders. Rodents that exhibit high locomotor activity when exploring an inescapable novel environment (high-responder; HR) are more susceptible to the reinforcing effects of many abused compounds, including nicotine, as compared to animals that exhibit low locomotor activity (low-responder; LR). Given that nicotinic acetylcholine receptor (nAChR) modulation of reward-related dopamine signaling at accumbal dopamine terminals is critical for the acquisition of drug self-administration, we hypothesized that nAChR modulation of dopamine release would be predicted by an animal's novelty response. Using voltammetry in the nucleus accumbens core of rats, we found that nicotine produced opposite effects in HR and LR animals on stimulation frequencies that model phasic dopamine release, whereby release magnitude was either augmented or attenuated, respectively. Further, nicotine suppressed dopamine release elected by stimulation frequencies that model tonic release in LR animals, but had no effect in HR animals. The differential effects of nicotine were likely due to desensitization of nAChRs, since the nAChR antagonists mecamylamine (non-selective, 2 μM), dihydro-beta-erythroidine (β2-selective, 500 nM), and α-conotoxin MII [H9A; L15A] (α6-selective, 100 nM) produced effects similar to nicotine. Moreover, dihydro-beta-erythroidine failed to show differential effects in HR and LR rats when applied after α-conotoxin MII [H9A; L15A], suggesting a critical role of α6β2 compared non α6-containing nAChRs in the differential effects observed in these phenotypes. These results delineate a potential mechanism for individual variability in behavioral sensitivity to nicotine.
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9
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Grasing K. A threshold model for opposing actions of acetylcholine on reward behavior: Molecular mechanisms and implications for treatment of substance abuse disorders. Behav Brain Res 2016; 312:148-62. [PMID: 27316344 DOI: 10.1016/j.bbr.2016.06.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 06/11/2016] [Accepted: 06/13/2016] [Indexed: 12/26/2022]
Abstract
The cholinergic system plays important roles in both learning and addiction. Medications that modify cholinergic tone can have pronounced effects on behaviors reinforced by natural and drug reinforcers. Importantly, enhancing the action of acetylcholine (ACh) in the nucleus accumbens and ventral tegmental area (VTA) dopamine system can either augment or diminish these behaviors. A threshold model is presented that can explain these seemingly contradictory results. Relatively low levels of ACh rise above a lower threshold, facilitating behaviors supported by drugs or natural reinforcers. Further increases in cholinergic tone that rise above a second upper threshold oppose the same behaviors. Accordingly, cholinesterase inhibitors, or agonists for nicotinic or muscarinic receptors, each have the potential to produce biphasic effects on reward behaviors. Pretreatment with either nicotinic or muscarinic antagonists can block drug- or food- reinforced behavior by maintaining cholinergic tone below its lower threshold. Potential threshold mediators include desensitization of nicotinic receptors and biphasic effects of ACh on the firing of medium spiny neurons. Nicotinic receptors with high- and low- affinity appear to play greater roles in reward enhancement and inhibition, respectively. Cholinergic inhibition of natural and drug rewards may serve as mediators of previously described opponent processes. Future studies should evaluate cholinergic agents across a broader range of doses, and include a variety of reinforced behaviors.
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Affiliation(s)
- Kenneth Grasing
- From the Substance Abuse Research Laboratory, 151, Kansas City Veterans Affairs Medical Center, 4801 Linwood Boulevard, Kansas City, MO 64128, United States; From the Division of Clinical Pharmacology, Department of Medicine, University of Kansas School of Medicine, Kansas City, KS 66160, United States.
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10
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Sukhtankar DD, Lagorio CH, Ko MC. Effects of the NOP agonist SCH221510 on producing and attenuating reinforcing effects as measured by drug self-administration in rats. Eur J Pharmacol 2014; 745:182-9. [PMID: 25446568 DOI: 10.1016/j.ejphar.2014.10.029] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 10/15/2014] [Accepted: 10/16/2014] [Indexed: 10/24/2022]
Abstract
Nociceptin/orphanin FQ peptide (NOP) receptor agonists attenuate morphine-induced conditioned place preference in rodents. However, it is not known whether NOP agonists have reinforcing properties or can inhibit mu opioid receptor (MOP)-mediated reinforcement as measured by drug self-administration in rodents. Further understanding the behavioral effects of NOP agonists could suggest them as having potential in attenuating reinforcing effects of opioids. In the first part of the study, reinforcing properties of selective NOP agonist SCH221510 were determined and compared with the full MOP agonist remifentanil under fixed-ratio 5 (FR5) and progressive-ratio (PR) schedules of drug self-administration. In the second part, effects of systemic and intracisternal pretreatment of SCH221510 were determined and compared with MOP antagonist naltrexone in attenuating reinforcing effects of remifentanil and a non-drug reinforcer (sucrose pellets). Remifentanil self-administration (0.3-10 µg/kg/infusion) generated a biphasic dose-response curve, characteristic of drugs with reinforcing properties. SCH221510 (3-300 µg/kg/infusion) self-administration resulted in flat dose-response curves and early break-points under the PR, indicative of drugs lacking reinforcing value. Intracisternally, but not systemically, administered SCH221510 (0.3-3 µg) attenuated remifentanil self-administration, comparable with systemic naltrexone (0.03-0.3 mg/kg). SCH221510 (1-3 µg), unlike naltrexone (0.03-1 mg/kg), attenuated responding for sucrose pellets. Both effects of SCH221510 were reversed by the NOP antagonist J-113397 (0.3-3 µg). These results suggest that SCH221510 does not function as a reinforcer in rats, and that it can attenuate the reinforcing value of MOP agonists; therefore, the potential utility of NOP agonists for the treatment of drug addiction warrants further evaluation.
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Affiliation(s)
- Devki D Sukhtankar
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.
| | - Carla H Lagorio
- Department of Psychology, University of Wisconsin-Eau Claire, Eau Claire, WI 54702, USA
| | - Mei-Chuan Ko
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA; Center for Comparative Medicine Research, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
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11
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Prast JM, Schardl A, Schwarzer C, Dechant G, Saria A, Zernig G. Reacquisition of cocaine conditioned place preference and its inhibition by previous social interaction preferentially affect D1-medium spiny neurons in the accumbens corridor. Front Behav Neurosci 2014; 8:317. [PMID: 25309368 PMCID: PMC4174134 DOI: 10.3389/fnbeh.2014.00317] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 08/27/2014] [Indexed: 11/13/2022] Open
Abstract
We investigated if counterconditioning with dyadic (i.e., one-to-one) social interaction, a strong inhibitor of the subsequent reacquisition of cocaine conditioned place preference (CPP), differentially modulates the activity of the diverse brain regions oriented along a mediolateral corridor reaching from the interhemispheric sulcus to the anterior commissure, i.e., the nucleus of the vertical limb of the diagonal band, the medial septal nucleus, the major island of Calleja, the intermediate part of the lateral septal nucleus, and the medial accumbens shell and core. We also investigated the involvement of the lateral accumbens core and the dorsal caudate putamen. The anterior cingulate 1 (Cg1) region served as a negative control. Contrary to our expectations, we found that all regions of the accumbens corridor showed increased expression of the early growth response protein 1 (EGR1, Zif268) in rats 2 h after reacquisition of CPP for cocaine after a history of cocaine CPP acquisition and extinction. Previous counterconditioning with dyadic social interaction inhibited both the reacquisition of cocaine CPP and the activation of the whole accumbens corridor. EGR1 activation was predominantly found in dynorphin-labeled cells, i.e., presumably D1 receptor-expressing medium spiny neurons (D1-MSNs), with D2-MSNs (immunolabeled with an anti-DRD2 antibody) being less affected. Cholinergic interneurons or GABAergic interneurons positive for parvalbumin, neuropeptide Y or calretinin were not involved in these CPP-related EGR1 changes. Glial cells did not show any EGR1 expression either. The present findings could be of relevance for the therapy of impaired social interaction in substance use disorders, depression, psychosis, and autism spectrum disorders.
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Affiliation(s)
- Janine M Prast
- Experimental Psychiatry Unit, Innsbruck Medical University Innsbruck, Austria
| | - Aurelia Schardl
- Experimental Psychiatry Unit, Innsbruck Medical University Innsbruck, Austria
| | | | - Georg Dechant
- Institute for Neuroscience, Innsbruck Medical University Innsbruck, Austria
| | - Alois Saria
- Experimental Psychiatry Unit, Innsbruck Medical University Innsbruck, Austria
| | - Gerald Zernig
- Experimental Psychiatry Unit, Innsbruck Medical University Innsbruck, Austria ; Department of Psychology, Leopold-Franzens University of Innsbruck Innsbruck, Austria
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12
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Carcoba LM, Orfila JE, Natividad LA, Torres OV, Pipkin JA, Ferree PL, Castañeda E, Moss DE, O'Dell LE. Cholinergic transmission during nicotine withdrawal is influenced by age and pre-exposure to nicotine: implications for teenage smoking. Dev Neurosci 2014; 36:347-55. [PMID: 24854235 DOI: 10.1159/000360133] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 01/28/2014] [Indexed: 11/19/2022] Open
Abstract
Adolescence is a unique period of development characterized by enhanced tobacco use and long-term vulnerability to neurochemical changes produced by adolescent nicotine exposure. In order to understand the underlying mechanisms that contribute to developmental differences in tobacco use, this study compared changes in cholinergic transmission during nicotine exposure and withdrawal in naïve adult rats compared to (1) adolescent rats and (2) adult rats that were pre-exposed to nicotine during adolescence. The first study compared extracellular levels of acetylcholine (ACh) in the nucleus accumbens (NAc) during nicotine exposure and precipitated withdrawal using microdialysis procedures. Adolescent (postnatal day, PND, 28-42) and adult rats (PND60-74) were prepared with osmotic pumps that delivered nicotine for 14 days (adolescents 4.7 mg/kg/day; adults 3.2 mg/kg/day; expressed as base). Another group of adults was exposed to nicotine during adolescence and then again in adulthood (pre-exposed adults) using similar methods. Control rats received a sham surgery. Following 13 days of nicotine exposure, the rats were implanted with microdialysis probes in the NAc. The following day, dialysis samples were collected during baseline and following systemic administration of the nicotinic receptor antagonist mecamylamine (1.5 and 3.0 mg/kg, i.p.) to precipitate withdrawal. A second study compared various metabolic differences in cholinergic transmission using the same treatment procedures as the first study. Following 14 days of nicotine exposure, the NAc was dissected and acetylcholinesterase (AChE) activity was compared across groups. In order to examine potential group differences in nicotine metabolism, blood plasma levels of cotinine (a nicotine metabolite) were also compared following 14 days of nicotine exposure. The results from the first study revealed that nicotine exposure increased baseline ACh levels to a greater extent in adolescent versus adult rats. During nicotine withdrawal, ACh levels in the NAc were increased in a similar manner in adolescent versus adult rats. However, the increase in ACh that was observed in adult rats experiencing nicotine withdrawal was blunted in pre-exposed adults. These neurochemical effects do not appear to be related to nicotine metabolism, as plasma cotinine levels were similar across all groups. The second study revealed that nicotine exposure increased AChE activity in the NAc to a greater extent in adolescent versus adult rats. There was no difference in AChE activity in pre-exposed versus naïve adult rats. In conclusion, our results suggest that nicotine exposure during adolescence enhances baseline ACh in the NAc. However, the finding that ACh levels were similar during withdrawal in adolescent and adult rats suggests that the enhanced vulnerability to tobacco use during adolescence is not related to age differences in withdrawal-induced increases in cholinergic transmission. Our results also suggest that exposure to nicotine during adolescence suppresses withdrawal-induced increases in cholinergic responses during withdrawal. Taken together, this report illustrates important short- and long-term changes within cholinergic systems that may contribute to the enhanced susceptibility to tobacco use during adolescence.
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Affiliation(s)
- Luis M Carcoba
- Department of Psychology, University of Texas at El Paso, El Paso, Tex., USA
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13
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Zernig G, Kummer KK, Prast JM. Dyadic social interaction as an alternative reward to cocaine. Front Psychiatry 2013; 4:100. [PMID: 24062696 PMCID: PMC3770939 DOI: 10.3389/fpsyt.2013.00100] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 08/26/2013] [Indexed: 12/16/2022] Open
Abstract
Individuals suffering from substance use disorders often show severely impaired social interaction, preferring drugs of abuse to the contact with others. Their impaired social interaction is doubly harmful for them as (1) therapy itself is based and dependent on social interaction and as (2) social interaction is not available to them as an "alternative", i.e., non-drug reward, decreasing their motivation to stop drug use. We therefore developed an animal experimental model to investigate the neurobiology of dyadic social interaction- vs. cocaine reward. We took care to avoid: (a) engaging sexual attraction-related aspects of such a social interaction and (b) hierarchical difference as confounding stimuli. The cocaine- or social interaction stimulus was offered - in a mutually exclusive setting - within the confines of a conditioned place preference (CPP) apparatus. In our paradigm, only four 15-min episodes of social interaction proved sufficient to (i) switch the rats' preference from cocaine-associated contextual stimuli to social interaction CPP and (ii) inhibit the subsequent reacquisition/reexpression of cocaine CPP. This behavioral effect was paralleled by a reversal of brain activation (i.e., EGR1 expression) in the nucleus accumbens, the central and basolateral amygdala, and the ventral tegmental area. Of relevance for the psychotherapy of addictive disorders, the most rewarding sensory component of the composite stimulus "social interaction" was touch. To test our hypothesis that motivation is encoded in neuron ensembles dedicated to specific reward scenarios, we are currently (1) mapping the neural circuits involved in cocaine- vs. social-interaction reward and (2) adapting our paradigm for C57BL/6 mice to make use of the plethora of transgenic models available in this species.
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Affiliation(s)
- Gerald Zernig
- Experimental Psychiatry Unit, Department of General Psychiatry and Social Psychiatry, Innsbruck Medical University , Innsbruck , Austria ; Department of Psychology, Leopold-Franzens University of Innsbruck , Innsbruck , Austria
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Prast JM, Kummer KK, Barwitz CM, Humpel C, Dechant G, Zernig G. Acetylcholine, drug reward and substance use disorder treatment: intra- and interindividual striatal and accumbal neuron ensemble heterogeneity may explain apparent discrepant findings. Pharmacology 2012; 90:264-73. [PMID: 23018268 DOI: 10.1159/000342636] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 08/13/2012] [Indexed: 11/19/2022]
Abstract
Converging evidence from different independent laboratories suggests that acetylcholine may play an important role in drug reward and that modulation of the cholinergic system may be useful for the treatment of substance use disorders. In this commentary, we try to reconcile apparently discrepant animal behavioral, human behavioral and clinical data with a unifying hypothesis positing that the modulation of drug-versus natural stimuli-mediated reward by cholinergic interneurons in the nucleus accumbens (and the dorsal striatum) is restricted to distinct neuron ensembles that show considerable intra- and interindividual variation with respect to their spatial distribution. The precise targeting of these interindividually variable neuron ensembles would be a prerequisite for a successful pharmacotherapy based on the modulation of the cholinergic system. We also provide experimental data to support our unifying hypothesis.
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Affiliation(s)
- Janine M Prast
- Experimental Psychiatry Unit, Innsbruck Medical University, Innsbruck, Austria
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15
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Noori HR, Fliegel S, Brand I, Spanagel R. The impact of acetylcholinesterase inhibitors on the extracellular acetylcholine concentrations in the adult rat brain: A meta-analysis. Synapse 2012; 66:893-901. [DOI: 10.1002/syn.21581] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 06/19/2012] [Indexed: 01/23/2023]
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16
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Activation of PKCzeta and PKMzeta in the nucleus accumbens core is necessary for the retrieval, consolidation and reconsolidation of drug memory. PLoS One 2012; 7:e30502. [PMID: 22348011 PMCID: PMC3277594 DOI: 10.1371/journal.pone.0030502] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 12/16/2011] [Indexed: 11/19/2022] Open
Abstract
One of the greatest challenges in the treatment of substance dependence is to reverse the control that drug-associated stimuli have gained over the addict's behavior, as these drug-associated memories increase the risk of relapse even after long periods of abstinence. We report here that inhibition of the atypical protein kinase C isoform PKCzeta and its constitutively active isoform PKMzeta with the pseudosubstrate inhibitor ZIP administered locally into the nucleus accumbens core reversibly inhibited the retrieval of drug-associated memory and drug (remifentanil) seeking, whereas a scrambled ZIP peptide or staurosporine, an effective inhibitor of c/nPKC-, CaMKII-, and PKA kinases that does not affect PKCzeta/PKMzeta activity, was without effect on these memory processes. Acquisition or extinction of drug-associated memory remained unaffected by PKCzeta- and PKMzeta inhibition.
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Fritz M, El Rawas R, Salti A, Klement S, Bardo MT, Kemmler G, Dechant G, Saria A, Zernig G. Reversal of cocaine-conditioned place preference and mesocorticolimbic Zif268 expression by social interaction in rats. Addict Biol 2011; 16:273-84. [PMID: 21309948 DOI: 10.1111/j.1369-1600.2010.00285.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Little is known how social interaction, if offered as an alternative to drug consumption, affects neural circuits involved in drug reinforcement and substance dependence. Conditioned place preference (CPP) for cocaine (15 mg/kg i.p.) or social interaction (15 minutes) as an alternative stimulus was investigated in male Sprague-Dawley rats. Four social interaction episodes with a male adult conspecific completely reversed cocaine CPP and were even able to prevent reacquisition of cocaine CPP. Social interaction also reversed cocaine CPP-induced expression of the immediate-early gene zif268 in the nucleus accumbens shell, the central and basolateral amygdala and the ventral tegmental area. These findings suggest that social interaction, if offered in a context that is clearly distinct from the previously drug-associated ones, may profoundly decrease the incentive salience of drug-associated contextual stimuli. The novel experimental design facilitates the neurobiological investigation of this phenomenon which may be beneficial for human drug users in treatment.
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Affiliation(s)
- Michael Fritz
- Experimental Psychiatry Unit, Medical University Innsbruck, Innrain 66a, A-6020 Innsbruck, Austria
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18
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Yee J, Famous KR, Hopkins TJ, McMullen MC, Pierce RC, Schmidt HD. Muscarinic acetylcholine receptors in the nucleus accumbens core and shell contribute to cocaine priming-induced reinstatement of drug seeking. Eur J Pharmacol 2011; 650:596-604. [PMID: 21034738 PMCID: PMC3033040 DOI: 10.1016/j.ejphar.2010.10.045] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 09/22/2010] [Accepted: 10/20/2010] [Indexed: 02/03/2023]
Abstract
Muscarinic acetylcholine receptors in the nucleus accumbens play an important role in mediating the reinforcing effects of cocaine. However, there is a paucity of data regarding the role of accumbal muscarinic acetylcholine receptors in the reinstatement of cocaine-seeking behavior. The goal of these experiments was to assess the role of muscarinic acetylcholine receptors in the nucleus accumbens core and shell in cocaine and sucrose priming-induced reinstatement. Rats were initially trained to self-administer cocaine or sucrose on a fixed-ratio schedule of reinforcement. Lever-pressing behavior was then extinguished and followed by a subsequent reinstatement phase during which operant responding was induced by either a systemic injection of cocaine in cocaine-experienced rats or non-contingent delivery of sucrose pellets in subjects with a history of sucrose self-administration. Results indicated that systemic administration of the muscarinic acetylcholine receptor antagonist scopolamine (5.0 mg/kg, i.p.) dose-dependently attenuated cocaine, but not sucrose, reinstatement. Furthermore, administration of scopolamine (36.0 μg) directly into the nucleus accumbens shell or core attenuated cocaine priming-induced reinstatement. In contrast, infusion of scopolamine (36.0 μg) directly into the accumbens core, but not shell, attenuated sucrose reinstatement, which suggests that muscarinic acetylcholine receptors in these two subregions of the nucleus accumbens have differential roles in sucrose seeking. Taken together, these results indicate that cocaine priming-induced reinstatement is mediated, in part, by increased signaling through muscarinic acetylcholine receptors in the shell subregion of the nucleus accumbens. Muscarinic acetylcholine receptors in the core of the accumbens, in contrast, appear to play a more general (i.e. not cocaine specific) role in motivated behaviors.
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Affiliation(s)
- Judy Yee
- Department of Pharmacology Boston University School of Medicine Boston, MA 02118
| | - Katie R. Famous
- Department of Pharmacology Boston University School of Medicine Boston, MA 02118
| | - Thomas J. Hopkins
- Center for Neurobiology and Behavior Department of Psychiatry University of Pennsylvania School of Medicine Philadelphia, PA 19104
| | - Michael C. McMullen
- Center for Neurobiology and Behavior Department of Psychiatry University of Pennsylvania School of Medicine Philadelphia, PA 19104
| | - R. Christopher Pierce
- Center for Neurobiology and Behavior Department of Psychiatry University of Pennsylvania School of Medicine Philadelphia, PA 19104
| | - Heath D. Schmidt
- Center for Neurobiology and Behavior Department of Psychiatry University of Pennsylvania School of Medicine Philadelphia, PA 19104
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Abstract
This paper is the 31st consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2008 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd, Flushing, NY 11367, United States.
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Kasture S, Vinci S, Ibba F, Puddu A, Marongiu M, Murali B, Pisanu A, Lecca D, Zernig G, Acquas E. Withania somnifera prevents morphine withdrawal-induced decrease in spine density in nucleus accumbens shell of rats: a confocal laser scanning microscopy study. Neurotox Res 2009; 16:343-55. [PMID: 19551457 DOI: 10.1007/s12640-009-9069-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2008] [Revised: 03/09/2009] [Accepted: 03/09/2009] [Indexed: 11/30/2022]
Abstract
Opiate withdrawal is associated with morphological changes of dopamine neurons in the ventral tegmental area and with reduction of spine density of second-order dendrites of medium size spiny neurons in the nucleus accumbens shell but not core. Withania somnifera has long been used in the Middle East, Africa, and India as a remedy for different conditions and diseases and a growing body of evidence points to its beneficial effects on a number of experimental models of neurological disorders. Recently, many studies focused on the potential neuritic regeneration and synaptic reconstruction properties of its methanolic extract and its constituents (withanolides). This study investigates whether morphine withdrawal-induced spine reduction in the nucleus accumbens is affected by the administration of a Withania somnifera extract. To this end, rats were chronically treated with Withania somnifera extract along with morphine or saline and, upon spontaneous (1 and 3 days) or pharmacologically precipitated withdrawal, their brains were fixed in Golgi-Cox stain for confocal microscopic examination. In a separate group of animals, Withania somnifera extract was administered during three days of spontaneous withdrawal. Withania somnifera extract treatment reduced the severity of the withdrawal syndrome when given during chronic morphine but not during withdrawal. In addition, treatment with Withania somnifera extract during chronic morphine, but not during withdrawal, fully prevented the reduction of spine density in the nucleus accumbens shell in spontaneous and pharmacologically precipitated morphine withdrawal. These results indicate that pretreatment with Withania somnifera extract protects from the structural changes induced by morphine withdrawal potentially providing beneficial effects on the consequences related to this condition.
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Affiliation(s)
- Sanjay Kasture
- Department of Toxicology, University of Cagliari, 09124 Cagliari, Italy
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Zhang D, Zhang H, Jin GZ, Zhang K, Zhen X. Single dose of morphine produced a prolonged effect on dopamine neuron activities. Mol Pain 2008; 4:57. [PMID: 19014677 PMCID: PMC2603002 DOI: 10.1186/1744-8069-4-57] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2008] [Accepted: 11/17/2008] [Indexed: 02/03/2023] Open
Abstract
Background Clinical observation and experimental studies have indicated that a single exposure to morphine could induce tolerance and dependence. It has become a concern in clinical antinociceptive practice. However, the underling mechanism remains unknown. This study was designed to explore the changes of dopamine (DA) neuron activities in the ventral tegmental area (VTA) by employing a spectral analysis followed single morphine treatment. Results Acute morphine treatment significantly increased not only the firing rate and firing population but also the power of slow oscillation of DA neurons in naïve rats. These changes lasted at least for 3 days following the morphine treatment. During this period of time, responses of the DA neurons to subsequent morphine challenge were diminished. We further demonstrated a transient desensitization of opiate receptors as monitored by GTPγS binding to G-proteins. The present study provided first direct evidence for the temporal changes in the VTA DA neuron activities and opiate receptors desensitization. Conclusion Prolonged VTA DA neuron activation and opiate receptors desensitization followed single morphine exposure may underlie the development of dependence and tolerance that may associate with the acute analgesic tolerance and acute addiction of morphine.
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Affiliation(s)
- Die Zhang
- State Key Laboratory of Drug Research, Department of Neuropharmacology, Shanghai Institute of Material Medica, Chinese Academy of Sciences, Shanghai, PR China
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22
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Ettenberg A. The runway model of drug self-administration. Pharmacol Biochem Behav 2008; 91:271-7. [PMID: 19032964 DOI: 10.1016/j.pbb.2008.11.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 11/06/2008] [Accepted: 11/08/2008] [Indexed: 01/01/2023]
Abstract
Behavioral scientists have employed operant runways as a means of investigating the motivational impact of incentive stimuli for the better part of the past 100 years. In this task, the speed with which a trained animal traverses a long straight alley for positive incentive stimuli, like food or water, provides a reliable index of the subject's motivation to seek those stimuli. The runway is therefore a particularly appropriate tool for investigating the drug-seeking behavior of animals working for drugs of abuse. The current review describes our laboratory's work over the past twenty years developing and implementing an operant runway model of drug self-administration. Procedures are described that methodologically dissociate the antecedent motivational processes that induce an animal to seek a drug, from the positive reinforcing consequences of actually earning the drug. Additional work is reviewed on the use of the runway method as a means of modeling the factors that often result in a "relapse" of drug self-administration after a period of abstinence (i.e., a response reinstatement test), as are runway studies that revealed the presence of opposing positive and negative consequences of self-administered cocaine. This body of work suggests that the runway method has served as a powerful behavioral tool for the study of the behavioral and neurobiological basis of drug self-administration.
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Affiliation(s)
- Aaron Ettenberg
- Behavioral Pharmacology Laboratory, Department of Psychology, University of California, Santa Barbara, CA 93106-9660, United States.
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