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Jacobs DS, Blough BE, Kohut SJ. Reinforcing and Stimulant-Like Effects of Methamphetamine Isomers in Rhesus Macaques. J Pharmacol Exp Ther 2021; 378:124-132. [PMID: 33986037 PMCID: PMC8407528 DOI: 10.1124/jpet.121.000548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 05/10/2021] [Indexed: 11/22/2022] Open
Abstract
Monoamine releasers such as d-methamphetamine (d-MA) can reduce cocaine use in laboratory studies and have been forwarded for the management of cocaine use disorder (CUD). However, the proven abuse liability of d-MA has limited enthusiasm for clinical use. The levorotatory isomer of MA, l-MA, appears to have lesser stimulant effects, possibly due to its preferential norepinephrine-releasing properties compared with dopamine. The present study evaluated the abuse potential of l-MA by comparing its reinforcing effects with known stimulant drugs of abuse in nonhuman primates. Adult rhesus macaques (N = 4) responded for intravenous injections of cocaine, d-MA, methcathinone (MCAT), or l-MA under a fixed-ratio (FR) schedule of reinforcement; reinforcing effectiveness was evaluated using behavioral economic demand procedures. In a separate cohort (N = 9), daily activity and food-reinforced responding were assessed during 100 days of treatment with daily dosages of l-MA (2.3 mg/kg per day, i.v.) or d-MA (0.74 mg/kg per day, i.v.) previously shown to decrease cocaine self-administration. Results show that all drugs maintained self-administration, with peak injections reaching ∼100 inj per session for cocaine, MCAT, and d-MA and ∼50 inj per session for l-MA . In demand studies, self-administration of each drug gradually decreased as FR size increased. The exponential model of demand indicated that the reinforcing effectiveness of l-MA was significantly less than the other drugs studied. Chronic l-MA treatment did not appreciably alter daily activity and only transiently suppressed food-reinforced responding. These data, coupled with previous findings that l-MA effectively reduces stimulant self-administration, suggest that l-MA, or other norepinephrine-preferring releasers, may serve as agonist medication for CUD with lesser abuse liability than common psychostimulants. SIGNIFICANCE STATEMENT: Development of pharmacotherapies for cocaine use disorder remains a formidable challenge. Agonist-based therapies show promise, but enthusiasm is tempered by the abuse liability of previously proposed medications. This study evaluated the abuse liability and chronic treatment effects of methamphetamine's levorotatory isomer (l-MA). l-MA demonstrated lower abuse liability compared with commonly abused stimulants and produced few untoward effects. In the context of recent studies demonstrating that l-MA attenuates stimulant self-administration, these findings support l-MA's potential as a pharmacotherapy for stimulant addiction.
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Affiliation(s)
- David S Jacobs
- McLean Hospital - Harvard Medical School, Belmont, Massachusetts (D.S.J., S.J.K.), and Research Triangle Institute, Research Triangle Park, North Carolina (B.E.B.)
| | - Bruce E Blough
- McLean Hospital - Harvard Medical School, Belmont, Massachusetts (D.S.J., S.J.K.), and Research Triangle Institute, Research Triangle Park, North Carolina (B.E.B.)
| | - Stephen J Kohut
- McLean Hospital - Harvard Medical School, Belmont, Massachusetts (D.S.J., S.J.K.), and Research Triangle Institute, Research Triangle Park, North Carolina (B.E.B.)
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Wakeford AGP, Sherwood AM, Prisinzano TE, Bergman J, Kohut SJ, Paronis CA. Discriminative-Stimulus Effects of Synthetic Cathinones in Squirrel Monkeys. Int J Neuropsychopharmacol 2021; 24:656-665. [PMID: 33909067 PMCID: PMC8378080 DOI: 10.1093/ijnp/pyab017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 04/06/2021] [Accepted: 04/26/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Synthetic cathinones display overlapping behavioral effects with psychostimulants (e.g., methamphetamine [MA]) and/or entactogens (e.g., 3,4-methylenedioxymethaphetamine [MDMA])-presumably reflecting their dopaminergic and/or serotonergic activity. The discriminative stimulus effects of MDMA thought to be mediated by such activity have been well characterized in rodents but have not been fully examined in nonhuman primates. METHODS The present studies were conducted to systematically evaluate the discriminative stimulus effects of 5 abused synthetic cathinones (methylenedioxypyrovalerone [MDPV], α-pyrrolidinovalerophenone [α-PVP], methcathinone [MCAT], mephedrone, and methylone) in adult male squirrel monkeys trained to distinguish intramuscular injections of MA (0.1 mg/kg; n = 4) or MDMA (0.6 mg/kg; n = 4) from vehicle. RESULTS Each training drug produced dose-dependent effects and, at the highest dose, full substitution. MDMA produced predominantly vehicle-like responding in the MA-trained group, whereas the highest dose of MA (0.56 mg/kg) produced partial substitution (approximately 90% appropriate lever responding in one-half of the subjects) in the MDMA-trained group. MDPV, α-PVP, and MCAT produced full substitution in MA-trained subjects, but, at the same or higher doses, only substituted for MDMA in one-half of the subjects, consistent with primarily dopaminergically mediated interoceptive effects. In contrast, mephedrone and methylone fully substituted in MDMA-trained subjects but failed to fully substitute for the training drug in MA-trained subjects, suggesting a primary role for serotonergic actions in their interoceptive effects. CONCLUSIONS These findings suggest that differences in the interoceptive effects of synthetic cathinones in nonhuman primates reflect differing compositions of monoaminergic actions that also may mediate their subjective effects in humans.
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Affiliation(s)
- Alison G P Wakeford
- McLean Hospital, Behavioral Biology Program, Belmont, Massachusetts, USA,Harvard Medical School, Department of Psychiatry, Boston, Massachusetts, USA,Correspondence: Alison G. P. Wakeford, PhD, Behavioral Biology Program, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, MA 02478, USA ()
| | - Alexander M Sherwood
- College of Pharmacy, University of Kentucky, Lexington, Kentucky, USA,Usona Institute, Madison, Wisconsin, USA
| | | | - Jack Bergman
- McLean Hospital, Behavioral Biology Program, Belmont, Massachusetts, USA,Harvard Medical School, Department of Psychiatry, Boston, Massachusetts, USA
| | - Stephen J Kohut
- McLean Hospital, Behavioral Biology Program, Belmont, Massachusetts, USA,Harvard Medical School, Department of Psychiatry, Boston, Massachusetts, USA
| | - Carol A Paronis
- McLean Hospital, Behavioral Biology Program, Belmont, Massachusetts, USA,Harvard Medical School, Department of Psychiatry, Boston, Massachusetts, USA
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Walther D, Shalabi AR, Baumann MH, Glennon RA. Systematic Structure-Activity Studies on Selected 2-, 3-, and 4-Monosubstituted Synthetic Methcathinone Analogs as Monoamine Transporter Releasing Agents. ACS Chem Neurosci 2019; 10:740-745. [PMID: 30354055 DOI: 10.1021/acschemneuro.8b00524] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Methcathinone analogs are appearing on the clandestine market at a rate nearly out-pacing the ability of investigators to examine them on an individual basis. To formulate structure-activity relationship (SAR) generalities, we examined the releasing ability of several simple methcathinone analogs at the three monoamine transporters (i.e., the dopamine, norepinephrine, and serotonin transporters, DAT, NET, and SERT, respectively) using in vitro assay methods. The analogs included methcathinone and 14 other compounds monosubstituted at the 2-, 3-, or 4-position. In general, (a) the 2-substituted analogs were less potent than either the 3- or 4-substituted analogs, (b) the 3- and 4-substituted analogs were relatively similar in potency, (c) methcathinone was the most selective as a DAT-releasing agent, and (d) the 3- and 4-CF3 analogs were the least DAT-selective. For the 15 compounds, there was a significant correlation ( r > 0.9) between DAT and NET potency, suggesting relatively similar structure-activity relationships (at least for the compounds examined here). Several of the compounds have appeared on the clandestine market since our studies were initiated, and the present results provide new information on how they might act.
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Affiliation(s)
- Donna Walther
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, United States
| | - Abdelrahman R. Shalabi
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Michael H. Baumann
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, United States
| | - Richard A. Glennon
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, Virginia 23298, United States
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Simmons SJ, Leyrer-Jackson JM, Oliver CF, Hicks C, Muschamp JW, Rawls SM, Olive MF. DARK Classics in Chemical Neuroscience: Cathinone-Derived Psychostimulants. ACS Chem Neurosci 2018; 9:2379-2394. [PMID: 29714473 DOI: 10.1021/acschemneuro.8b00147] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Cathinone is a plant alkaloid found in khat leaves of perennial shrubs grown in East Africa. Similar to cocaine, cathinone elicits psychostimulant effects which are in part attributed to its amphetamine-like structure. Around 2010, home laboratories began altering the parent structure of cathinone to synthesize derivatives with mechanisms of action, potencies, and pharmacokinetics permitting high abuse potential and toxicity. These "synthetic cathinones" include 4-methylmethcathinone (mephedrone), 3,4-methylenedioxypyrovalerone (MDPV), and the empathogenic agent 3,4-methylenedioxymethcathinone (methylone) which collectively gained international popularity following aggressive online marketing as well as availability in various retail outlets. Case reports made clear the health risks associated with these agents and, in 2012, the Drug Enforcement Agency of the United States placed a series of synthetic cathinones on Schedule I under emergency order. Mechanistically, cathinone and synthetic derivatives work by augmenting monoamine transmission through release facilitation and/or presynaptic transport inhibition. Animal studies confirm the rewarding and reinforcing properties of synthetic cathinones by utilizing self-administration, place conditioning, and intracranial self-stimulation assays and additionally show persistent neuropathological features which demonstrate a clear need to better understand this class of drugs. This Review will thus detail (i) historical context of cathinone use and the rise of "dark" synthetic derivatives, (ii) structural features and mechanisms of synthetic cathinones, (iii) behavioral effects observed clinically and in animals under controlled laboratory conditions, and (iv) neurotransmitters and circuits that may be targeted to manage synthetic cathinone abuse in humans.
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Affiliation(s)
- Steven J. Simmons
- Center for Substance Abuse Research (CSAR), Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania 19140, United States
| | | | - Chicora F. Oliver
- Center for Substance Abuse Research (CSAR), Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Callum Hicks
- Center for Substance Abuse Research (CSAR), Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania 19140, United States
| | - John W. Muschamp
- Center for Substance Abuse Research (CSAR), Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Scott M. Rawls
- Center for Substance Abuse Research (CSAR), Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania 19140, United States
| | - M. Foster Olive
- Department of Psychology, Arizona State University, Tempe, Arizona 85281, United States
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Djikic T, Martí Y, Spyrakis F, Lau T, Benedetti P, Davey G, Schloss P, Yelekci K. Human dopamine transporter: the first implementation of a combined in silico/in vitro approach revealing the substrate and inhibitor specificities. J Biomol Struct Dyn 2018; 37:291-306. [PMID: 29334320 DOI: 10.1080/07391102.2018.1426044] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Parkinson's disease (PD) is characterized by the loss of dopamine-generating neurons in the substantia nigra and corpus striatum. Current treatments alleviate PD symptoms rather than exerting neuroprotective effect on dopaminergic neurons. New drugs targeting the dopaminergic neurons by specific uptake through the human dopamine transporter (hDAT) could represent a viable strategy for establishing selective neuroprotection. Molecules able to increase the bioactive amount of extracellular dopamine, thereby enhancing and compensating a loss of dopaminergic neurotransmission, and to exert neuroprotective response because of their accumulation in the cytoplasm, are required. By means of homology modeling, molecular docking, and molecular dynamics simulations, we have generated 3D structure models of hDAT in complex with substrate and inhibitors. Our results clearly reveal differences in binding affinity of these compounds to the hDAT in the open and closed conformations, critical for future drug design. The established in silico approach allowed the identification of promising substrate compounds that were subsequently analyzed for their efficiency in inhibiting hDAT-dependent fluorescent substrate uptake, through in vitro live cell imaging experiments. Taken together, our work presents the first implementation of a combined in silico/in vitro approach enabling the selection of promising dopaminergic neuron-specific substrates.
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Affiliation(s)
- Teodora Djikic
- a Department of Bioinformatics and Genetics , Kadir Has University , Cibali campus, Fatih 34083 , Istanbul , Turkey
| | - Yasmina Martí
- b Hector Institute for Translational Brain Research, Central Institute of Mental Health, Medical Faculty Mannheim , Heidelberg University , Mannheim J5, 68159 , Germany.,f Biochemical Laboratory, Psychiatry and Psychotherapy Department, Central Institute of Mental Health, Medical Faculty Mannheim , Heidelberg University , Mannheim J5, 68159 , Germany
| | - Francesca Spyrakis
- c Department of Drug Science and Technology , University of Turin , via P. Giuria 9, Turin 10125 , Italy
| | - Thorsten Lau
- b Hector Institute for Translational Brain Research, Central Institute of Mental Health, Medical Faculty Mannheim , Heidelberg University , Mannheim J5, 68159 , Germany
| | - Paolo Benedetti
- d Department of Chemistry, Biology and Biotechnology , University of Perugia , via Elce di sotto 8, Perugia 06123 , Italy
| | - Gavin Davey
- e School of Biochemistry and Immunology , Trinity College Dublin , Dublin 2, Ireland
| | - Patrick Schloss
- f Biochemical Laboratory, Psychiatry and Psychotherapy Department, Central Institute of Mental Health, Medical Faculty Mannheim , Heidelberg University , Mannheim J5, 68159 , Germany
| | - Kemal Yelekci
- a Department of Bioinformatics and Genetics , Kadir Has University , Cibali campus, Fatih 34083 , Istanbul , Turkey
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Smith DA, Negus SS, Poklis JL, Blough BE, Banks ML. Cocaine-like discriminative stimulus effects of alpha-pyrrolidinovalerophenone, methcathinone and their 3,4-methylenedioxy or 4-methyl analogs in rhesus monkeys. Addict Biol 2017; 22:1169-1178. [PMID: 27060605 DOI: 10.1111/adb.12399] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 02/25/2016] [Accepted: 03/01/2016] [Indexed: 01/20/2023]
Abstract
Synthetic cathinones are beta-ketone amphetamine analogs that have emerged as a heterogeneous class of abused compounds that function as either monoamine transporter substrates or inhibitors. Pre-clinical drug discrimination procedures are useful for interrogating structure-activity relationships of abuse-related drug effects; however, in vivo structure-activity relationship comparisons between synthetic cathinones with different mechanisms of action are lacking. The aim of the present study was to determine whether the cocaine-like discriminative stimulus effects of the monoamine transporter inhibitor alpha-pyrrolidinovalerophenone (alpha-PVP) and the monoamine transporter substrate methcathinone were differentially sensitive to 3,4-methylenedioxy and 4-methyl substitutions. Male rhesus monkeys (n = 4) were trained to discriminate intramuscular cocaine (0.32 mg/kg) from saline in a two-key food-reinforced discrimination procedure. Potency and timecourse of cocaine-like discriminative stimulus effects were determined for (±)-alpha-PVP, (±)-methcathinone and their 3,4-methylenedioxy or 4-methyl analogs. Alpha-PVP and methcathinone produced dose- and time-dependent cocaine-like effects. A 3,4-methylenedioxy addition to either alpha-PVP or methcathinone (methylone) did not alter the potency or efficacy to produce cocaine-like effects, but did prolong the time course. A 4-methyl addition to alpha-PVP (pyrovalerone) did not alter the potency or efficacy to produce cocaine-like effects, but did prolong the time course. In contrast, addition of a 4-methyl moiety to methcathinone (4MMC; mephedrone) significantly attenuated efficacy to produce cocaine-like effects. Overall, these results suggest different structural requirements for cocaine-like discriminative stimulus effects of monoamine transporter inhibitor and substrate synthetic cathinone analogs. Given that 4MMC is more hydrophobic than MDMC, these results suggest that hydrophobicity may be an important determinant for limiting monoamine transporter substrate abuse-related behavioral effects.
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Affiliation(s)
- Douglas A. Smith
- Department of Pharmacology and Toxicology; Virginia Commonwealth University; Richmond VA USA 23298
| | - S. Stevens Negus
- Department of Pharmacology and Toxicology; Virginia Commonwealth University; Richmond VA USA 23298
- Institute for Drug and Alcohol Studies; Virginia Commonwealth University; Richmond VA USA 23298
| | - Justin L. Poklis
- Department of Pharmacology and Toxicology; Virginia Commonwealth University; Richmond VA USA 23298
| | - Bruce E. Blough
- Center for Drug Discovery; Research Triangle Institute; Research Triangle Park NC USA 27709
| | - Matthew L. Banks
- Department of Pharmacology and Toxicology; Virginia Commonwealth University; Richmond VA USA 23298
- Institute for Drug and Alcohol Studies; Virginia Commonwealth University; Richmond VA USA 23298
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7
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Abstract
Until recently, there was rather little interest in the structure-activity relationships (SARs) of cathinone analogs because so few agents were available and because they represented a relatively minor drug abuse problem. Most of the early SAR was formulated on the basis of behavioral (e.g., locomotor and drug discrimination) studies using rodents. With the emergence on the clandestine market in the last few years of a large number of new cathinone analogs, termed "synthetic cathinones", and the realization that they likely act at dopamine, norepinephrine, and/or serotonin transporters as releasing agents (i.e., as substrates) or reuptake inhibitors (i.e., as transport blockers), it has now become possible to better examine their SAR and even their quantitative SAR (QSAR), in a more effective and systematic manner. An SAR picture is beginning to emerge, and key structural features, such as the nature of the terminal amine, the size of the α-substituent, stereochemistry, and the presence and position of aromatic substituents, are being found to impact action (i.e., as releasing agents or reuptake inhibitors) and transporter selectivity.
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Affiliation(s)
- Richard A Glennon
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA.
| | - Małgorzata Dukat
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, 23298, USA
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8
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Kohut SJ, Bergman J, Blough BE. Effects of L-methamphetamine treatment on cocaine- and food-maintained behavior in rhesus monkeys. Psychopharmacology (Berl) 2016; 233:1067-75. [PMID: 26713332 PMCID: PMC4761269 DOI: 10.1007/s00213-015-4186-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 12/11/2015] [Indexed: 10/22/2022]
Abstract
RATIONALE Monoamine releasers with prominent dopaminergic actions, e.g., D-methamphetamine (D-MA), significantly reduce cocaine use and craving in clinical and preclinical laboratory studies. However, D-MA and related drugs also display high abuse potential, which limits their acceptability as agonist replacement medications for the management of Cocaine Use Disorder. OBJECTIVES The L-isomer of methamphetamine (L-MA), unlike D-MA, has preferential noradrenergic actions and is used medicinally with low, if any, abuse liability. The present study was conducted to determine whether L-MA could serve as an agonist replacement medication by both mimicking interoceptive effects of cocaine and decreasing intravenous (IV) cocaine self-administration. METHODS Separate groups (N = 4-5) of rhesus monkeys were studied to determine whether L-MA could (1) substitute for cocaine in subjects that discriminated intramuscular (IM) cocaine (0.4 mg/kg) from saline and (2) decrease IV cocaine self-administration under a second-order FR2(VR16:S) schedule of reinforcement. RESULTS L-MA, like D-MA but with approximately 5-fold lesser potency, substituted for cocaine in drug discrimination experiments in a dose-dependent manner. In IV self-administration studies, 5-10-day treatments with continuously infused L-MA (0.032-0.32 mg/kg/h, IV) dose-dependently decreased cocaine-maintained responding; the highest dosage reduced cocaine intake to levels of saline self-administration without appreciable effects on food-maintained responding. CONCLUSIONS These results indicate that L-MA both shares discriminative stimulus effects with cocaine and reduces cocaine self-administration in a behaviorally selective manner. L-MA and other compounds with a similar pharmacological profile deserve further evaluation for the management of Cocaine Use Disorder.
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Affiliation(s)
- Stephen J. Kohut
- Department of Psychiatry, Harvard Medical School, Belmont, MA, USA
| | - Jack Bergman
- Department of Psychiatry, Harvard Medical School, Belmont, MA, USA
| | - Bruce E. Blough
- Center for Organic and Medicinal Chemistry, Research Triangle Institute, Research Triangle Park, NC, USA
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Gatch MB, Dolan SB, Forster MJ. Comparative Behavioral Pharmacology of Three Pyrrolidine-Containing Synthetic Cathinone Derivatives. J Pharmacol Exp Ther 2015; 354:103-10. [PMID: 25998047 DOI: 10.1124/jpet.115.223586] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 05/14/2015] [Indexed: 11/22/2022] Open
Abstract
Synthetic cathinones, often sold as "bath salts," are a popular class of recreational drugs used as quasi-legal alternatives to cocaine, methamphetamine, and methylenedioxymethamphetamine. The increased prevalence and health consequences of synthetic cathinone use has prompted regulatory agencies to control a number of these compounds; however, a broad class of analogous compounds known as the second-generation cathinones has been brought to the market to take the place of the banned synthetic cathinone derivatives. The current study aims to characterize the behavioral pharmacology of three pyrrolidinylated second-generation cathinones: 4-methyl-α-pyrrolidinopropiophenone (4'-MePPP), α-pyrrolidinopropiobutiophenone (α-PBP), and α-pyrrolidinopentiophenone (α-PVP). Locomotor activity was tested in mice over an 8-hour period. The discriminative stimulus effects of these compounds were tested in rats trained to discriminate either cocaine or methamphetamine. The rewarding effects of these drugs were assessed in mice using conditioned place preference. Both α-PBP and α-PVP produced long-lasting increases in locomotor activity across a wide range of doses, whereas 4'-MePPP produced locomotor stimulation only at 30 mg/kg. Both α-PBP and α-PVP fully substituted for the discriminative stimulus effects of both cocaine and methamphetamine, whereas 4'-MePPP substituted fully for the discriminative stimulus effects of methamphetamine only. Both α-PBP and α-PVP produced conditioned place preference in an inverted U-shaped dose effect, whereas 4'-MePPP did not produce conditioned place preference. These findings suggest that α-PBP and α-PVP are likely to be recreationally used and have potential for addiction and abuse, but 4'-MePPP may not.
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Affiliation(s)
- Michael B Gatch
- Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas
| | - Sean B Dolan
- Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas
| | - Michael J Forster
- Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas
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Bonano JS, Banks ML, Kolanos R, Sakloth F, Barnier ML, Glennon RA, Cozzi NV, Partilla JS, Baumann MH, Negus SS. Quantitative structure-activity relationship analysis of the pharmacology of para-substituted methcathinone analogues. Br J Pharmacol 2015; 172:2433-44. [PMID: 25438806 DOI: 10.1111/bph.13030] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 11/20/2014] [Accepted: 11/27/2014] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Methcathinone (MCAT) is a potent monoamine releaser and parent compound to emerging drugs of abuse including mephedrone (4-CH3 MCAT), the para-methyl analogue of MCAT. This study examined quantitative structure-activity relationships (QSAR) for MCAT and six para-substituted MCAT analogues on (a) in vitro potency to promote monoamine release via dopamine and serotonin transporters (DAT and SERT, respectively), and (b) in vivo modulation of intracranial self-stimulation (ICSS), a behavioural procedure used to evaluate abuse potential. Neurochemical and behavioural effects were correlated with steric (Es ), electronic (σp ) and lipophilic (πp ) parameters of the para substituents. EXPERIMENTAL APPROACH For neurochemical studies, drug effects on monoamine release through DAT and SERT were evaluated in rat brain synaptosomes. For behavioural studies, drug effects were tested in male Sprague-Dawley rats implanted with electrodes targeting the medial forebrain bundle and trained to lever-press for electrical brain stimulation. KEY RESULTS MCAT and all six para-substituted analogues increased monoamine release via DAT and SERT and dose- and time-dependently modulated ICSS. In vitro selectivity for DAT versus SERT correlated with in vivo efficacy to produce abuse-related ICSS facilitation. In addition, the Es values of the para substituents correlated with both selectivity for DAT versus SERT and magnitude of ICSS facilitation. CONCLUSIONS AND IMPLICATIONS Selectivity for DAT versus SERT in vitro is a key determinant of abuse-related ICSS facilitation by these MCAT analogues, and steric aspects of the para substituent of the MCAT scaffold (indicated by Es ) are key determinants of this selectivity.
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Affiliation(s)
- J S Bonano
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
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Gatch MB, Rutledge MA, Forster MJ. Discriminative and locomotor effects of five synthetic cathinones in rats and mice. Psychopharmacology (Berl) 2015; 232:1197-205. [PMID: 25281225 PMCID: PMC4361374 DOI: 10.1007/s00213-014-3755-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 09/20/2014] [Indexed: 11/25/2022]
Abstract
RATIONALE Synthetic cathinones continue to be sold as "legal" alternatives to methamphetamine or cocaine. As these marginally legal compounds become controlled, suppliers move to other, unregulated compounds. OBJECTIVES The purpose of these experiments was to determine whether several temporarily controlled cathinone compounds, which are currently abused on the street, stimulate motor activity and have discriminative stimulus effects similar to cocaine and/or methamphetamine. METHODS Methcathinone, pentedrone, pentylone, 3-fluoromethcathinone (3-FMC), and 4-methylethcathinone (4-MEC) were tested for locomotor stimulant effects in mice and subsequently for substitution in rats trained to discriminate cocaine (10 mg/kg, i.p.) or methamphetamine (1 mg/kg, i.p.) from saline. RESULTS Methcathinone, pentedrone, and pentylone produced locomotor stimulant effects which lasted up to 6 h. In addition, pentylone produced convulsions and lethality at 100 mg/kg. 4-MEC produced locomotor stimulant effects which lasted up to 2 h. Methcathinone, pentedrone, pentylone, 3-FMC, and 4-MEC each produced discriminative stimulus effects similar to those of cocaine and methamphetamine. CONCLUSIONS All of the tested compounds produce discriminative stimulus effects similar to either those of cocaine, methamphetamine, or both, which suggests that these compounds are likely to have similar abuse liability to cocaine and/or methamphetamine. Pentylone may be more dangerous on the street, as it produced adverse effects at doses that produced maximal stimulant-like effects.
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Affiliation(s)
- Michael B Gatch
- Pharmacology & Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107-2699, USA,
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12
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The role of serotonin in drug use and addiction. Behav Brain Res 2014; 277:146-92. [PMID: 24769172 DOI: 10.1016/j.bbr.2014.04.007] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 04/04/2014] [Accepted: 04/05/2014] [Indexed: 12/26/2022]
Abstract
The use of psychoactive drugs is a wide spread behaviour in human societies. The systematic use of a drug requires the establishment of different drug use-associated behaviours which need to be learned and controlled. However, controlled drug use may develop into compulsive drug use and addiction, a major psychiatric disorder with severe consequences for the individual and society. Here we review the role of the serotonergic (5-HT) system in the establishment of drug use-associated behaviours on the one hand and the transition and maintenance of addiction on the other hand for the drugs: cocaine, amphetamine, methamphetamine, MDMA (ecstasy), morphine/heroin, cannabis, alcohol, and nicotine. Results show a crucial, but distinct involvement of the 5-HT system in both processes with considerable overlap between psychostimulant and opioidergic drugs and alcohol. A new functional model suggests specific adaptations in the 5-HT system, which coincide with the establishment of controlled drug use-associated behaviours. These serotonergic adaptations render the nervous system susceptible to the transition to compulsive drug use behaviours and often overlap with genetic risk factors for addiction. Altogether we suggest a new trajectory by which serotonergic neuroadaptations induced by first drug exposure pave the way for the establishment of addiction.
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Monoamine transporter inhibitors and substrates as treatments for stimulant abuse. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 69:129-76. [PMID: 24484977 DOI: 10.1016/b978-0-12-420118-7.00004-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The acute and chronic effects of abused psychostimulants on monoamine transporters and associated neurobiology have encouraged development of candidate medications that target these transporters. Monoamine transporters, in general, and dopamine transporters, in particular, are critical molecular targets that mediate abuse-related effects of psychostimulants such as cocaine and amphetamine. Moreover, chronic administration of psychostimulants can cause enduring changes in neurobiology reflected in dysregulation of monoamine neurochemistry and behavior. The current review will evaluate evidence for the efficacy of monoamine transporter inhibitors and substrates to reduce abuse-related effects of stimulants in preclinical assays of stimulant self-administration, drug discrimination, and reinstatement. In considering deployment of monoamine transport inhibitors and substrates as agonist-type medications to treat stimulant abuse, the safety and abuse liability of the medications are an obvious concern, and this will also be addressed. Future directions in drug discovery should identify novel medications that retain efficacy to decrease stimulant use but possess lower abuse liability and evaluate the degree to which efficacious medications can attenuate or reverse neurobiological effects of chronic stimulant use.
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