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Keighron JD, Giancola JB, Shaffer RJ, DeMarco EM, Coggiano MA, Slack RD, Hauck Newman A, Tanda G. Distinct effects of (R)-modafinil and its (R)- and (S)-fluoro-analogs on mesolimbic extracellular dopamine assessed by voltammetry and microdialysis in rats. Eur J Neurosci 2019; 50:2045-2053. [PMID: 30402972 PMCID: PMC8294075 DOI: 10.1111/ejn.14256] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 10/29/2018] [Accepted: 10/31/2018] [Indexed: 02/06/2023]
Abstract
Psychostimulant use disorders remain an unabated public health concern worldwide, but no FDA approved medications are currently available for treatment. Modafinil (MOD), like cocaine, is a dopamine reuptake inhibitor and one of the few drugs evaluated in clinical trials that has shown promise for the treatment of cocaine or methamphetamine use disorders in some patient subpopulations. Recent structure-activity relationship and preclinical studies on a series of MOD analogs have provided insight into modifications of its chemical structure that may lead to advancements in clinical efficacy. Here, we have tested the effects of the clinically available (R)-enantiomer of MOD on extracellular dopamine levels in the nucleus accumbens shell, a mesolimbic dopaminergic projection field that plays significant roles in various aspects of psychostimulant use disorders, measured in vivo by fast-scan cyclic voltammetry and by microdialysis in Sprague-Dawley rats. We have compared these results with those obtained under identical experimental conditions with two novel and enantiopure bis(F) analogs of MOD, JBG1-048 and JBG1-049. The results show that (R)-modafinil (R-MOD), JBG1-048, and JBG1-049, when administered intravenously with cumulative drug-doses, will block the dopamine transporter and reduce the clearance rate of dopamine, increasing its extracellular levels. Differences among the compounds in their maximum stimulation of dopamine levels, and in their time course of effects were also observed. These data highlight the mechanistic underpinnings of R-MOD and its bis(F) analogs as pharmacological tools to guide the discovery of novel medications to treat psychostimulant use disorders.
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Affiliation(s)
- Jacqueline D. Keighron
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - JoLynn B. Giancola
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Rachel J. Shaffer
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Emily M. DeMarco
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Mark A. Coggiano
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Rachel D. Slack
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Amy Hauck Newman
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
| | - Gianluigi Tanda
- Medication Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Department of Health and Human Services; 333 Cassell Drive, TRIAD Bldg., Baltimore, MD, USA, 21224
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Keighron JD, Quarterman JC, Cao J, DeMarco EM, Coggiano MA, Gleaves A, Slack RD, Zanettini C, Newman AH, Tanda G. Effects of ( R)-Modafinil and Modafinil Analogues on Dopamine Dynamics Assessed by Voltammetry and Microdialysis in the Mouse Nucleus Accumbens Shell. ACS Chem Neurosci 2019; 10:2012-2021. [PMID: 30645944 DOI: 10.1021/acschemneuro.8b00340] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Recent discoveries have improved our understanding of the physiological and pathological roles of the dopamine transporter (DAT); however, only a few drugs are clinically available for DAT-implicated disorders. Among those drugs, modafinil (MOD) and its ( R)-enantiomer (R-MOD) have been used off-label as therapies for psychostimulant use disorders, but they have shown limited effectiveness in clinical trials. Recent preclinical studies on MOD and R-MOD have led to chemically modified structures aimed toward improving their neurobiological properties that might lead to more effective therapeutics for stimulant use disorders. This study examines three MOD analogues (JJC8-016, JJC8-088, and JJC8-091) with improved DAT affinities compared to their parent compound. These compounds were investigated for their effects on the neurochemistry (brain microdialysis and FSCV) and behavior (ambulatory activity) of male Swiss-Webster mice. Our data indicate that these compounds have dissimilar effects on tonic and phasic dopamine in the nucleus accumbens shell and variability in producing ambulatory activity. These results suggest that small changes in the chemical structure of a DAT inhibitor can cause compounds such as JJC8-088 to produce effects similar to abused psychostimulants like cocaine. In contrast, other compounds like JJC8-091 do not share cocaine-like effects and have a more atypical DAT-inhibitor profile, which may prove to be an advancement in the treatment of psychostimulant use disorders.
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Mereu M, Chun LE, Prisinzano TE, Newman AH, Katz JL, Tanda G. The unique psychostimulant profile of (±)-modafinil: investigation of behavioral and neurochemical effects in mice. Eur J Neurosci 2016; 45:167-174. [PMID: 27545285 DOI: 10.1111/ejn.13376] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 07/08/2016] [Accepted: 08/18/2016] [Indexed: 11/29/2022]
Abstract
Blockade of dopamine (DA) reuptake via the dopamine transporter (DAT) is a primary mechanism identified as underlying the therapeutic actions of (±)-modafinil (modafinil) and its R-enantiomer, armodafinil. Herein, we explored the neurochemical and behavioral actions of modafinil to better characterize its psychostimulant profile. Swiss-Webster mice were implanted with microdialysis probes in the nucleus accumbens shell (NAS) or core (NAC) to evaluate changes in DA levels related to acute reinforcing actions of drugs of abuse. Additionally, subjective effects were studied in mice trained to discriminate 10 mg/kg cocaine (i.p.) from saline. Modafinil (17-300 mg/kg, i.p.) significantly increased NAS and NAC DA levels that at the highest doses reached ~300% at 1 h, and lasted > 6 h in duration. These elevated DA levels did not show statistically significant regional differences between the NAS and NAC. Modafinil produced cocaine-like subjective effects at 56-100 mg/kg when administered at 5 and 60 min before the start of the session, and enhanced cocaine effects when the two were administered in combination. Despite sharing subjective effects with cocaine, modafinil's psychostimulant profile was unique compared to that of cocaine and like compounds. Modafinil had lower potency and efficacy than cocaine in stimulating NAS DA. In addition, the cocaine-like subjective effects of modafinil were obtained at lower doses and earlier onset times than expected based on its dopaminergic effects. These studies suggest that although inhibition of DA reuptake may be a primary mechanism underlying modafinil's therapeutic actions, non DA-dependent actions may be playing a role in its psychostimulant profile.
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Affiliation(s)
- Maddalena Mereu
- Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA
| | - Lauren E Chun
- Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA
| | - Thomas E Prisinzano
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS, USA
| | - Amy H Newman
- Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA.,Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Jonathan L Katz
- Psychobiology Section, Molecular Neuropsychiatry Research Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA
| | - Gianluigi Tanda
- Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA
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Kohut SJ, Hiranita T, Hong SK, Ebbs AL, Tronci V, Green J, Garcés-Ramírez L, Chun LE, Mereu M, Newman AH, Katz JL, Tanda G. Preference for distinct functional conformations of the dopamine transporter alters the relationship between subjective effects of cocaine and stimulation of mesolimbic dopamine. Biol Psychiatry 2014; 76:802-9. [PMID: 24853388 PMCID: PMC4353924 DOI: 10.1016/j.biopsych.2014.03.031] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 03/08/2014] [Accepted: 03/13/2014] [Indexed: 11/26/2022]
Abstract
BACKGROUND Subjective effects of cocaine are mediated primarily by dopamine (DA) transporter (DAT) blockade. The present study assessed the hypothesis that different DAT conformational equilibria regulate differences in cocaine-like subjective effects and extracellular DA induced by diverse DA-uptake inhibitors (DUIs). METHODS The relationship between cocaine-like subjective effects and stimulation of mesolimbic DA levels by standard DUIs (cocaine, methylphenidate, WIN35,428) and atypical DUIs (benztropine analogs: AHN1-055, AHN2-005, JHW007) was investigated using cocaine discrimination and DA microdialysis procedures in rats. RESULTS All drugs stimulated DA levels with different maxima and time courses. Standard DUIs, which preferentially bind outward-facing DAT conformations, fully substituted for cocaine, consistently producing cocaine-like subjective effects at DA levels of 100-125% over basal values, regardless of dose or pretreatment time. The atypical DUIs, with DAT binding minimally affected by DAT conformation, produced inconsistent cocaine-like subjective effects. Full effects were obtained, if at all, only at a few doses and pretreatment times and at DA levels 600-700% greater than basal values. Importantly, the linear, time-independent, relationship between cocaine-like subjective effects and DA stimulation obtained with standard DUIs was not obtained with the atypical DUIs. CONCLUSIONS These results suggest a time-related desensitization process underlying the reduced cocaine subjective effects of atypical DUIs that may be differentially induced by the binding modalities identified using molecular approaches. Since the DAT is the target of several drugs for treating neuropsychiatric disorders, such as attention-deficit/hyperactivity disorder, these results help to identify safe and effective medications with minimal cocaine-like subjective effects that contribute to abuse liability.
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Affiliation(s)
- Stephen J Kohut
- Psychobiology, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland
| | - Takato Hiranita
- Psychobiology, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland
| | - Soo-Kyung Hong
- Psychobiology, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland; Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Aaron L Ebbs
- Psychobiology, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland
| | - Valeria Tronci
- Psychobiology, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland
| | - Jennifer Green
- Psychobiology, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland
| | - Linda Garcés-Ramírez
- Psychobiology, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland; Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, México
| | - Lauren E Chun
- Psychobiology, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland
| | - Maddalena Mereu
- Psychobiology, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland
| | - Amy H Newman
- Medicinal Chemistry Sections, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland; Medications Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland
| | - Jonathan L Katz
- Psychobiology, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland
| | - Gianluigi Tanda
- Psychobiology, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland; Medications Development Program, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse/Intramural Research Program/National Institutes of Health/Department of Health and Human Services, Baltimore, Maryland.
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Tanda G, Li SM, Mereu M, Thomas AM, Ebbs AL, Chun LE, Tronci V, Green JL, Zou MF, Kopajtic TA, Newman AH, Katz JL. Relations between stimulation of mesolimbic dopamine and place conditioning in rats produced by cocaine or drugs that are tolerant to dopamine transporter conformational change. Psychopharmacology (Berl) 2013; 229:307-21. [PMID: 23612854 PMCID: PMC3758386 DOI: 10.1007/s00213-013-3109-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 04/05/2013] [Indexed: 10/26/2022]
Abstract
RATIONALE Dopamine transporter (DAT) conformation plays a role in the effectiveness of cocaine-like and other DAT inhibitors. Cocaine-like stimulants are intolerant to DAT conformation changes having decreased potency in cells transfected with DAT constructs that face the cytosol compared to wild-type DAT. In contrast, analogs of benztropine (BZT) are among compounds that are less affected by DAT conformational change. METHODS We compared the displacement of radioligand binding to various mammalian CNS sites, acute stimulation of accumbens shell dopamine levels, and place conditioning in rats among cocaine and four BZT analogs with Cl substitutions on the diphenyl-ether system including two with carboalkoxy substitutions at the 2-position of the tropane ring. RESULTS Binding assays confirmed high-affinity and selectivity for the DAT with the BZT analogs which also produced significant stimulation of mesolimbic dopamine efflux. Because BZT analogs produced temporal patterns of extracellular dopamine levels different from those by cocaine (3-10 mg/kg, i.p.), the place conditioning produced by BZT analogs and cocaine was compared at doses and times at which both the increase in dopamine levels and rates of increase were similar to those produced by an effective dose of cocaine. Despite this equilibration, none of the BZT analogs tested produced significant place conditioning. CONCLUSIONS The present results extend previous findings suggesting that cocaine-like actions are dependent on a binding equilibrium that favors the outward conformational state of the DAT. In contrast, BZT analogs with reduced dependence on DAT conformation have reduced cocaine-like behavioral effects and may prove useful in development of medications for stimulant abuse.
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Affiliation(s)
- Gianluigi Tanda
- Psychobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Su Min Li
- Psychobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Maddalena Mereu
- Psychobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Alexandra M. Thomas
- Psychobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Aaron L. Ebbs
- Psychobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | | | - Valeria Tronci
- Psychobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Jennifer L. Green
- Psychobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Mu-Fa Zou
- Medicinal Chemistry Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Theresa A. Kopajtic
- Psychobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Amy Hauck Newman
- Medicinal Chemistry Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Jonathan L. Katz
- Psychobiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
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Garcés-Ramírez L, Green JL, Hiranita T, Kopajtic TA, Mereu M, Thomas AM, Mesangeau C, Narayanan S, McCurdy CR, Katz JL, Tanda G. Sigma receptor agonists: receptor binding and effects on mesolimbic dopamine neurotransmission assessed by microdialysis. Biol Psychiatry 2011; 69:208-17. [PMID: 20950794 DOI: 10.1016/j.biopsych.2010.07.026] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 07/26/2010] [Accepted: 07/28/2010] [Indexed: 11/22/2022]
Abstract
BACKGROUND Subtypes of sigma (σ) receptors, σ₁ and σ₂, can be pharmacologically distinguished, and each may be involved in substance-abuse disorders. σ-Receptor antagonists block cocaine place conditioning and σ-receptor agonists are self-administered in rats that previously self-administered cocaine. Self-administration of abused drugs has been related to increased dopamine (DA) neurotransmission, however, σ-receptor agonist effects on mesolimbic DA are not fully characterized. METHODS Receptor-binding studies assessed affinities of σ-receptor ligands for σ-receptor subtypes and the DA transporter; effects on DA transmission in the rat nucleus accumbens shell were assessed using in vivo microdialysis. RESULTS Cocaine (.1-1.0 mg/kg intravenous [IV]), the nonselective σ(½)-receptor agonist DTG (1.0-5.6 mg/kg IV), and the selective σ₁-receptor agonist PRE-084 (.32-10 mg/kg IV) dose-dependently increased DA to ∼275%, ∼150%, and ∼160% maxima, respectively. DTG-induced stimulation of DA was antagonized by the nonselective σ(½)-receptor antagonist BD 1008 (10 mg/kg intraperitoneal [IP]) and the preferential σ₂-receptor antagonist SN 79 (1-3 mg/kg IP), but not by the preferential σ₁-receptor antagonist, BD 1063 (10-30 mg/kg IP). Neither PRE-084 nor cocaine was antagonized by BD 1063 or BD 1008. CONCLUSIONS σ-Receptor agonists stimulated DA in a brain area critical for reinforcing effects of cocaine. DTG effects on DA appear to be mediated by σ₂-receptors rather than σ₁-receptors. However, DA stimulation by cocaine or PRE-084 does not likely involve σ-receptors. The relatively low potency on DA transmission of the selective σ₁-receptor agonist, PRE-084, and its previously reported potent reinforcing effects, suggest a dopamine-independent reinforcing pathway that may contribute to substance-abuse disorders.
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