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D-amphetamine maintenance therapy reduces cocaine use in female rats. Psychopharmacology (Berl) 2022; 239:3755-3770. [PMID: 36357743 DOI: 10.1007/s00213-022-06271-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 10/19/2022] [Indexed: 11/12/2022]
Abstract
RATIONALE D-amphetamine maintenance therapy is a promising strategy to reduce drug use in cocaine use disorder (addiction). In both male rats and human cocaine users, d-amphetamine treatment reduces cocaine-taking and -seeking. However, this has not been examined systematically in female animals, even though cocaine addiction afflicts both sexes, and the sexes can differ in their response to cocaine. OBJECTIVES We determined how d-amphetamine maintenance therapy during cocaine self-administration influences cocaine use in female rats. METHODS In experiment 1, two groups of female rats received 14 intermittent access (IntA) cocaine self-administration sessions. One group received concomitant d-amphetamine maintenance treatment (COC + A rats; 5 mg/kg/day, via minipump), the other group did not (COC rats). After discontinuing d-amphetamine treatment, we measured responding for cocaine under a progressive ratio schedule, responding under extinction, and cocaine-primed reinstatement of drug-seeking. In experiment 2, we assessed the effects of d-amphetamine maintenance on these measures in already IntA cocaine-experienced rats. Thus, rats first received 14 IntA cocaine self-administration sessions without d-amphetamine. They then received 14 more IntA sessions, now either with (COC/COC + A rats) or without (COC/COC rats) concomitant d-amphetamine treatment. RESULTS In both experiments, d-amphetamine treatment did not significantly influence ongoing cocaine self-administration behaviour. After d-amphetamine treatment cessation, cocaine-primed reinstatement of cocaine-seeking was also unchanged. However, after d-amphetamine treatment cessation, rats responded less for cocaine both under progressive ratio and extinction conditions. CONCLUSIONS D-amphetamine treatment can both prevent and reverse increases in the motivation to take and seek cocaine in female animals.
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Abstract
Numerous drugs elicit locomotor stimulant effects at appropriate doses; however, we typically reserve the term psychostimulant to refer to drugs with affinity for monoamine reuptake transporters. This chapter comprises select experiments that have characterized the discriminative stimulus effects of psychostimulants using drug discrimination procedures. The substitution profiles of psychostimulants in laboratory rodents are generally consistent with those observed in human and nonhuman primate drug discrimination experiments. Notably, two major classes of psychostimulants can be distinguished as those that function as passive monoamine reuptake inhibitors (such as cocaine) and those that function as substrates for monoamine transporters and stimulate monoamine release (such as the amphetamines). Nevertheless, the discriminative stimulus effects of both classes of psychostimulant are quite similar, and drugs from different classes will substitute for one another. Most importantly, for both the cocaine-like and amphetamine-like psychostimulants, dopaminergic mechanisms most saliently determine discriminative stimulus effects, but these effects can be modulated by alterations in noradrenergic and serotonergic neurotransmission as well. Thusly, the drug discrimination assay is useful for characterizing the interoceptive effects of psychostimulants and determining the mechanisms that contribute to their subjective effects in humans.
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Affiliation(s)
- Michael D Berquist
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Slot 638, Little Rock, AR, 72205, USA
| | - William E Fantegrossi
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Slot 638, Little Rock, AR, 72205, USA.
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Dolan SB, Shetty RA, Forster MJ, Gatch MB. Impure but not inactive: Behavioral pharmacology of dibenzylpiperazine, a common by-product of benzylpiperazine synthesis. J Psychopharmacol 2018; 32:802-810. [PMID: 29909719 PMCID: PMC7504971 DOI: 10.1177/0269881118780613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Substituted piperazines comprise a substantial proportion of the novel psychoactive substance market. Among the most widely abused piperazine compounds are meta-chlorophenylpiperazine (mCPP), tri-fluoromethylphenylpiperazine (TFMPP), and, especially, benzylpiperazine (BZP), which are commonly incorporated, either alone or in combination, in illicit "party pills" or "ecstasy" formulations. Illicit synthesis of BZP often results in production of an impure by-product dibenzylpiperazine (DBZP), which frequently appears alongside BZP in these formulations; however, despite its ubiquity, little information exists regarding the abuse liability of DBZP. AIMS The current study aimed to evaluate the abuse-related behavioral pharmacology of DBZP. METHODS DBZP, mCPP, and TFMPP were tested in parallel in mice in locomotor activity and conditioned place preference assays, and in a drug discrimination assay with rats trained to discriminate either methamphetamine, cocaine, (±)-3,4-methylenedioxymethamphetamine (MDMA), or -2,5-dimethoxy-4-methylamphetamine(DOM). RESULTS Each of the compounds tested produced dose-dependent decreases in locomotor activity. DBZP substituted fully for methamphetamine, produced subthreshold drug-appropriate responding for cocaine and MDMA, and failed to substitute for DOM. Conversely, TFMPP and mCPP only produced subthreshold drug-appropriate responding for methamphetamine and MDMA, respectively, and both compounds failed to substitute for cocaine or DOM. None of the compounds tested produced a place preference. DBZP produced convulsions in rats at the highest dose tested. CONCLUSIONS These data indicate that DBZP is more similar to BZP, albeit with lower potency and efficacy, than its serotonergic piperazine counterparts, and is a behaviorally-active compound with some abuse liability and potential for adverse health effects.
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Affiliation(s)
- Sean B Dolan
- Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, USA
| | - Ritu A Shetty
- Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, USA
| | - Michael J Forster
- Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, USA
| | - Michael B Gatch
- Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, USA
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Kohut SJ, Jacobs DS, Rothman RB, Partilla JS, Bergman J, Blough BE. Cocaine-like discriminative stimulus effects of "norepinephrine-preferring" monoamine releasers: time course and interaction studies in rhesus monkeys. Psychopharmacology (Berl) 2017; 234:3455-3465. [PMID: 28889212 PMCID: PMC5747253 DOI: 10.1007/s00213-017-4731-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 08/29/2017] [Indexed: 12/15/2022]
Abstract
RATIONALE The therapeutic potential of monoamine releasers with prominent dopaminergic effects is hindered by their high abuse liability. OBJECTIVES The present study examined the effects of several novel "norepinephrine (NE)-preferring" monoamine releasers relative to non-selective monoamine releasers, d-amphetamine and d-methamphetamine, in rhesus monkeys trained to discriminate cocaine. NE-preferring releasers were approximately 13-fold more potent for NE compared to dopamine release and ranged in potency for serotonin release (PAL-329 < l-methamphetamine < PAL-169). METHODS Adult rhesus macaques were trained to discriminate 0.4 mg/kg, IM cocaine on a 30-response fixed ratio schedule of food reinforcement. Substitution studies determined the extent to which test drugs produced cocaine-like discriminative stimulus effects and their time course. Drug interaction studies determined whether pretreatment with test drugs altered the discriminable effects of cocaine. RESULTS Results show that cocaine, d-amphetamine, and d-methamphetamine dose-dependently substituted for cocaine with similar potencies. Among the "NE-preferring" releasers, PAL-329 and l-methamphetamine also dose-dependently substituted for cocaine but differed in potency. PAL-169 failed to substitute for cocaine up to a dose that disrupted responding. When administered prior to cocaine, only d-amphetamine and PAL-329 significantly shifted the cocaine dose-effect function leftward indicating enhancement of cocaine's discriminative stimulus effects. CONCLUSIONS These data suggest that greater potency for NE relative to dopamine release (up to 13-fold) does not interfere with the ability of a monoamine releaser to produce cocaine-like discriminative effects but that increased serotonin release may have an inhibitory effect. Further characterization of these and other "NE-preferring" monoamine releasers should provide insight into their potential for the management of cocaine addiction.
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Affiliation(s)
- Stephen J Kohut
- McLean Hospital - Harvard Medical School, 115 Mill Street, Belmont, MA, 02478, USA.
| | - David S Jacobs
- McLean Hospital - Harvard Medical School, 115 Mill Street, Belmont, MA, 02478, USA
| | - Richard B Rothman
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - John S Partilla
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Jack Bergman
- McLean Hospital - Harvard Medical School, 115 Mill Street, Belmont, MA, 02478, USA
| | - Bruce E Blough
- Research Triangle Institute, Research Triangle Park, NC, USA
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Lazenka MF, Freitas KC, Henck S, Negus SS. Relief of Pain-Depressed Behavior in Rats by Activation of D1-Like Dopamine Receptors. J Pharmacol Exp Ther 2017; 362:14-23. [PMID: 28411257 DOI: 10.1124/jpet.117.240796] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 04/13/2017] [Indexed: 12/11/2022] Open
Abstract
Clinically significant pain often includes a decrease in both behavior and mesolimbic dopamine signaling. Indirect and/or direct dopamine receptor agonists may alleviate pain-related behavioral depression. To test this hypothesis, the present study compared effects of indirect and direct dopamine agonists in a preclinical assay of pain-depressed operant responding. Male Sprague-Dawley rats with chronic indwelling microelectrodes in the medial forebrain bundle were trained in an intracranial self-stimulation (ICSS) procedure to press a lever for pulses of electrical brain stimulation. Intraperitoneal injection of dilute lactic acid served as an acute noxious stimulus to depress ICSS. Intraperitoneal lactic acid-induced depression of ICSS was dose-dependently blocked by the dopamine transporter inhibitor methylphenidate and the D1-selective agonist SKF82958, but not by the D2/3-selective agonists quinpirole, pramipexole, or sumanirole. The antinociceptive effects of methylphenidate and SKF82958 were blocked by the D1-selective antagonist SCH39166. Acid-induced stimulation of a stretching response was evaluated in separate groups of rats, but all agonists decreased acid-stimulated stretching, and antagonism experiments were inconclusive due to direct effects of the antagonists when administered alone. Taken together, these results suggest that D1-receptor stimulation is both sufficient to block acid-induced depression of ICSS and necessary for methylphenidate antinociception in this procedure. Conversely, D2/3-receptor stimulation is not sufficient to relieve pain-depressed behavior. These results support the hypothesis that pain-related depression of dopamine D1 receptor signaling contributes to pain-related depression of behavior in rats. Additionally, these results support further consideration of indirect dopamine agonists and direct D1 receptor agonists as candidate treatments for pain-related behavioral depression.
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Affiliation(s)
- Matthew F Lazenka
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Kelen C Freitas
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Sydney Henck
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - S Stevens Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
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Liu ZH, Wang DM, Fan SF, Li DW, Luo ZW. Synergistic effects and related bioactive mechanism of Potentilla fruticosa L. leaves combined with Ginkgo biloba extracts studied with microbial test system (MTS). Altern Ther Health Med 2016; 16:495. [PMID: 27905920 PMCID: PMC5134079 DOI: 10.1186/s12906-016-1485-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 11/14/2016] [Indexed: 11/10/2022]
Abstract
BACKGROUND Potentilla fruticosa, also called "Jinlaomei" and "Gesanghua", is widely used as folk herbs in traditional Tibetan medicine in China to treat inflammations, wounds, certain forms of cancer, diarrhoea, diabetes and other ailments. Previous research found P. fruticosa leaf extract (C-3) combined with Ginkgo biloba extracts (EGb) showed obvious synergistic effects in a variety of oxidation systems. The aim of the present study was to further confirm the synergy of P. fruticosa combined with EGb viewed from physiological bioavailability and explore the related bioactive mechanism behind the synergism. METHODS The microbial test system (MTS) was adopted to evaluate the related bioactive mechanism. The synergistic effects were evaluated by isobolographic analysis. The H2O2 production rate and antioxidant enzyme (Catalase (CAT), Peroxidase (POD), Superoxide dismutase (SOD), Glutathione peroxidase (GSH-PX)) activities were determined by the colorimetric method. Enzyme gene (CAT, SOD) expression was measured by real time-PCR. RESULTS The MTS antioxidant activity results showed the combination of C-3 + EGb exhibited synergistic effects especially at the ratio 5:1. Components of isorhamnetin and caffeic acid in C-3 and EGb displayed strong antioxidant activities on MTS and their combination also showed significant synergy in promoting H2O2 production. The combinations of C-3 + EGb and isorhamnetin + caffeic acid promoted CAT and SOD enzyme activities and the ratio 1:1 exhibited the strongest synergy while no obvious promotion on POD and GSH-PX enzyme activities was found. Both combinations above promoted gene expression of CAT and SOD enzymes and the ratio 1:1 exhibited the strongest synergy. CONCLUSIONS Antioxidant activity results in MTS further confirmed the significant synergy of C-3 combined with EGb and isorhamnetin combined with caffeic acid. The synergy of C-3 combined with EGb may be attributed to the combination of isorhamnetin + caffeic acid, which promoted CAT and SOD enzyme gene expression and further promoted the enzyme activities in E. coli. This study could further provide rational basis for optimizing the physiological bioavailability of P. fruticosa by using natural and safe antioxidants in low doses to produce new medicines and functional products.
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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] [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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Golovko AI, Bonitenko EY, Ivanov MB, Barinov VA, Zatsepin EP. The neurochemical bases of the pharmacological activity of ligands of monoamine-transport systems. NEUROCHEM J+ 2016. [DOI: 10.1134/s1819712416030065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Collins GT, Abbott M, Galindo K, Rush EL, Rice KC, France CP. Discriminative Stimulus Effects of Binary Drug Mixtures: Studies with Cocaine, MDPV, and Caffeine. J Pharmacol Exp Ther 2016; 359:1-10. [PMID: 27493274 DOI: 10.1124/jpet.116.234252] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 08/01/2016] [Indexed: 11/22/2022] Open
Abstract
Illicit drug preparations often include more than one pharmacologically active compound. For example, cocaine and synthetic cathinones [e.g., 3,4-methylenedioxypyrovalerone (MDPV)] are often mixed with caffeine before sale. Caffeine is likely added to these preparations because it is inexpensive and legal; however, caffeine might also mimic or enhance some of the effects of cocaine or MDPV. In these studies, male Sprague-Dawley rats were trained to discriminate 10 mg/kg cocaine from saline, and the discriminative stimulus effects of cocaine, caffeine, and MDPV were evaluated alone and as binary mixtures (cocaine and caffeine, MDPV and caffeine, and cocaine and MDPV) at fixed-dose ratios of 3:1, 1:1, and 1:3 relative to the dose of each drug that produced 50% cocaine-appropriate responding. Dose-addition analyses were used to determine the nature of the drug-drug interactions for each mixture (e.g., additive, supra-additive, or subadditive). Although additive interactions were observed for most mixtures, supra-additive interactions were observed at the 50% effect level for the 1:1 mixture of cocaine and caffeine and at the 80% effect level for all three mixtures of cocaine and caffeine, as well as for the 3:1 and 1:3 mixtures of cocaine and MDPV. These results demonstrate that with respect to cocaine-like discriminative stimulus effects, caffeine can function as a substitute in drug preparations containing either cocaine or MDPV, with enhancements of cocaine-like effects possible under certain conditions. Further research is needed to determine whether similar interactions exist for other abuse-related or toxic effects of drug preparations, including cocaine, synthetic cathinones, and caffeine.
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Affiliation(s)
- Gregory T Collins
- Departments of Pharmacology (G.T.C., M.A., K.G., E.L.R., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, and South Texas Veterans Health Care System (G.T.C.), San Antonio, Texas; and Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland (K.C.R.)
| | - Megan Abbott
- Departments of Pharmacology (G.T.C., M.A., K.G., E.L.R., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, and South Texas Veterans Health Care System (G.T.C.), San Antonio, Texas; and Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland (K.C.R.)
| | - Kayla Galindo
- Departments of Pharmacology (G.T.C., M.A., K.G., E.L.R., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, and South Texas Veterans Health Care System (G.T.C.), San Antonio, Texas; and Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland (K.C.R.)
| | - Elise L Rush
- Departments of Pharmacology (G.T.C., M.A., K.G., E.L.R., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, and South Texas Veterans Health Care System (G.T.C.), San Antonio, Texas; and Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland (K.C.R.)
| | - Kenner C Rice
- Departments of Pharmacology (G.T.C., M.A., K.G., E.L.R., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, and South Texas Veterans Health Care System (G.T.C.), San Antonio, Texas; and Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland (K.C.R.)
| | - Charles P France
- Departments of Pharmacology (G.T.C., M.A., K.G., E.L.R., C.P.F.) and Psychiatry (C.P.F.), University of Texas Health Science Center at San Antonio, and South Texas Veterans Health Care System (G.T.C.), San Antonio, Texas; and Chemical Biology Research Branch, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland (K.C.R.)
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Hong WC, Kopajtic TA, Xu L, Lomenzo SA, Jean B, Madura JD, Surratt CK, Trudell ML, Katz JL. 2-Substituted 3β-Aryltropane Cocaine Analogs Produce Atypical Effects without Inducing Inward-Facing Dopamine Transporter Conformations. J Pharmacol Exp Ther 2016; 356:624-34. [PMID: 26769919 DOI: 10.1124/jpet.115.230722] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 01/07/2016] [Indexed: 11/22/2022] Open
Abstract
Previous structure-activity relationship studies indicate that a series of cocaine analogs, 3β-aryltropanes with 2β-diarylmethoxy substituents, selectively bind to the dopamine transporter (DAT) with nanomolar affinities that are 10-fold greater than the affinities of their corresponding 2α-enantiomers. The present study compared these compounds to cocaine with respect to locomotor effects in mice, and assessed their ability to substitute for cocaine (10 mg/kg, i.p.) in rats trained to discriminate cocaine from saline. Despite nanomolar DAT affinity, only the 2β-Ph2COCH2-3β-4-Cl-Ph analog fully substituted for cocaine-like discriminative effects. Whereas all of the 2β compounds increased locomotion, only the 2β-(4-ClPh)PhCOCH2-3β-4-Cl-Ph analog had cocaine-like efficacy. None of the 2α-substituted compounds produced either of these cocaine-like effects. To explore the molecular mechanisms of these drugs, their effects on DAT conformation were probed using a cysteine-accessibility assay. Previous reports indicate that cocaine binds with substantially higher affinity to the DAT in its outward (extracellular)- compared with inward-facing conformation, whereas atypical DAT inhibitors, such as benztropine, have greater similarity in affinity to these conformations, and this is postulated to explain their divergent behavioral effects. All of the 2β- and 2α-substituted compounds tested altered cysteine accessibility of DAT in a manner similar to cocaine. Furthermore, molecular dynamics of in silico inhibitor-DAT complexes suggested that the 2-substituted compounds reach equilibrium in the binding pocket in a cocaine-like fashion. These behavioral, biochemical, and computational results show that aryltropane analogs can bind to the DAT and stabilize outward-facing DAT conformations like cocaine, yet produce effects that differ from those of cocaine.
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Affiliation(s)
- Weimin C Hong
- Department of Pharmaceutical Sciences, Butler University, Indianapolis, Indiana (W.C.H.); Psychobiology Section (T.A.K., J.L.K.), Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland; Chemistry Department (L.X., S.A.L., M.L.T.), University of New Orleans, New Orleans, Louisiana; Department of Chemistry and Biochemistry (B.J., J.D.M.) and Division of Pharmaceutical Sciences (C.K.S.), Duquesne University, Pittsburgh, Pennsylvania
| | - Theresa A Kopajtic
- Department of Pharmaceutical Sciences, Butler University, Indianapolis, Indiana (W.C.H.); Psychobiology Section (T.A.K., J.L.K.), Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland; Chemistry Department (L.X., S.A.L., M.L.T.), University of New Orleans, New Orleans, Louisiana; Department of Chemistry and Biochemistry (B.J., J.D.M.) and Division of Pharmaceutical Sciences (C.K.S.), Duquesne University, Pittsburgh, Pennsylvania
| | - Lifen Xu
- Department of Pharmaceutical Sciences, Butler University, Indianapolis, Indiana (W.C.H.); Psychobiology Section (T.A.K., J.L.K.), Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland; Chemistry Department (L.X., S.A.L., M.L.T.), University of New Orleans, New Orleans, Louisiana; Department of Chemistry and Biochemistry (B.J., J.D.M.) and Division of Pharmaceutical Sciences (C.K.S.), Duquesne University, Pittsburgh, Pennsylvania
| | - Stacey A Lomenzo
- Department of Pharmaceutical Sciences, Butler University, Indianapolis, Indiana (W.C.H.); Psychobiology Section (T.A.K., J.L.K.), Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland; Chemistry Department (L.X., S.A.L., M.L.T.), University of New Orleans, New Orleans, Louisiana; Department of Chemistry and Biochemistry (B.J., J.D.M.) and Division of Pharmaceutical Sciences (C.K.S.), Duquesne University, Pittsburgh, Pennsylvania
| | - Bernandie Jean
- Department of Pharmaceutical Sciences, Butler University, Indianapolis, Indiana (W.C.H.); Psychobiology Section (T.A.K., J.L.K.), Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland; Chemistry Department (L.X., S.A.L., M.L.T.), University of New Orleans, New Orleans, Louisiana; Department of Chemistry and Biochemistry (B.J., J.D.M.) and Division of Pharmaceutical Sciences (C.K.S.), Duquesne University, Pittsburgh, Pennsylvania
| | - Jeffry D Madura
- Department of Pharmaceutical Sciences, Butler University, Indianapolis, Indiana (W.C.H.); Psychobiology Section (T.A.K., J.L.K.), Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland; Chemistry Department (L.X., S.A.L., M.L.T.), University of New Orleans, New Orleans, Louisiana; Department of Chemistry and Biochemistry (B.J., J.D.M.) and Division of Pharmaceutical Sciences (C.K.S.), Duquesne University, Pittsburgh, Pennsylvania
| | - Christopher K Surratt
- Department of Pharmaceutical Sciences, Butler University, Indianapolis, Indiana (W.C.H.); Psychobiology Section (T.A.K., J.L.K.), Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland; Chemistry Department (L.X., S.A.L., M.L.T.), University of New Orleans, New Orleans, Louisiana; Department of Chemistry and Biochemistry (B.J., J.D.M.) and Division of Pharmaceutical Sciences (C.K.S.), Duquesne University, Pittsburgh, Pennsylvania
| | - Mark L Trudell
- Department of Pharmaceutical Sciences, Butler University, Indianapolis, Indiana (W.C.H.); Psychobiology Section (T.A.K., J.L.K.), Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland; Chemistry Department (L.X., S.A.L., M.L.T.), University of New Orleans, New Orleans, Louisiana; Department of Chemistry and Biochemistry (B.J., J.D.M.) and Division of Pharmaceutical Sciences (C.K.S.), Duquesne University, Pittsburgh, Pennsylvania
| | - Jonathan L Katz
- Department of Pharmaceutical Sciences, Butler University, Indianapolis, Indiana (W.C.H.); Psychobiology Section (T.A.K., J.L.K.), Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland; Chemistry Department (L.X., S.A.L., M.L.T.), University of New Orleans, New Orleans, Louisiana; Department of Chemistry and Biochemistry (B.J., J.D.M.) and Division of Pharmaceutical Sciences (C.K.S.), Duquesne University, Pittsburgh, Pennsylvania
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Dopaminergic mediation of the discriminative stimulus functions of modafinil in rats. Psychopharmacology (Berl) 2015; 232:4411-9. [PMID: 26374456 DOI: 10.1007/s00213-015-4065-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 08/30/2015] [Indexed: 10/23/2022]
Abstract
RATIONALE Modafinil is a wake-promoting drug with FDA approval for the treatment of excessive daytime sleepiness that has been prescribed for ADHD and recently assessed as a potential treatment for psychostimulant dependence. Previous research indicates that modafinil modestly increases locomotor activity and produces similar discriminative stimulus effects to psychostimulants in rodents, although the subjective effects of modafinil are reportedly distinct from those of cocaine or amphetamine in humans with a history of psychostimulant abuse. OBJECTIVES The current study employed drug discrimination procedures in rats to examine the pharmacological actions contributing to modafinil's discriminative stimulus functions. METHODS Eight male Sprague-Dawley rats were trained to discriminate intragastric administration of 256 mg/kg modafinil from vehicle (5% arabic gum) under a FR 20 schedule of food reinforcement. Substitution tests were conducted with various dopaminergic agents (d-amphetamine, cocaine, PNU-91356A, GBR 12909, methylphenidate) and nondopaminergic agents (nicotine, ethanol). Antagonist tests were conducted with the selective D1 antagonist, SCH 39166, and the nonselective D2 antagonist, haloperidol. RESULTS Rats trained to discriminate modafinil displayed complete stimulus generalization to cocaine, methylphenidate, and GBR 12909 and the discrimination was completely blocked by both SCH 39166 and haloperidol. Evidence for significant partial substitution was obtained with d-amphetamine, PNU-91356A, and nicotine. CONCLUSIONS Results strongly support the role of dopaminergic mechanisms in the discriminative stimulus functions of modafinil, although further evaluation regarding the contribution of other neurotransmitter systems to these effects should be continued. The findings are discussed in light of clinical research efforts with modafinil as a treatment for psychostimulant dependence.
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12
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Influence of sensitization on the discriminative stimulus effects of methylphenidate in mice. Behav Pharmacol 2015; 25:766-74. [PMID: 25325285 DOI: 10.1097/fbp.0000000000000095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Methylphenidate (MPH) remains an important therapy for attention-deficit hyperactivity disorder, but aspects of its pharmacology remain unclear. In the present study, we used a regimen of MPH (8 mg/kg daily×14 days) in C57BL/6J mice to determine whether establishing locomotor sensitization to MPH influenced the acquisition and the dose-response function of MPH in a classic drug discrimination procedure. MPH-sensitized mice (SENS group) showed enhanced locomotor activity to the 8 mg/kg exposure dose as well as a 2 mg/kg dose before discrimination training. However, the SENS mice did not acquire discrimination of either a low dose (2 mg/kg) or a higher dose (4 mg/kg) of MPH any more rapidly than the CTRL mice. Further, during generalization testing, the dose-response functions for the SENS and CTRL mice were identical. Therefore, we did not find that previous exposure to MPH, which produced a sensitized locomotor response, facilitated MPH discrimination.
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Dürsteler KM, Berger EM, Strasser J, Caflisch C, Mutschler J, Herdener M, Vogel M. Clinical potential of methylphenidate in the treatment of cocaine addiction: a review of the current evidence. Subst Abuse Rehabil 2015; 6:61-74. [PMID: 26124696 PMCID: PMC4476488 DOI: 10.2147/sar.s50807] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Background Cocaine use continues to be a public health problem, yet there is no proven effective pharmacotherapy for cocaine dependence. A promising approach to treating cocaine dependence may be agonist-replacement therapy, which is already used effectively in the treatment of opioid and tobacco dependence. The replacement approach for cocaine dependence posits that administration of a long-acting stimulant medication should normalize the neurochemical and behavioral perturbations resulting from chronic cocaine use. One potential medication to be substituted for cocaine is methylphenidate (MPH), as this stimulant possesses pharmacobehavioral properties similar to those of cocaine. Aim To provide a qualitative review addressing the rationale for the use of MPH as a cocaine substitute and its clinical potential in the treatment of cocaine dependence. Methods We searched MEDLINE for clinical studies using MPH in patients with cocaine abuse/dependence and screened the bibliographies of the articles found for pertinent literature. Results MPH, like cocaine, increases synaptic dopamine by inhibiting dopamine reuptake. The discriminative properties, reinforcing potential, and subjective effects of MPH and cocaine are almost identical and, importantly, MPH has been found to substitute for cocaine in animals and human volunteers under laboratory conditions. When taken orally in therapeutic doses, its abuse liability, however, appears low, which is especially true for extended-release MPH preparations. Though there are promising data in the literature, mainly from case reports and open-label studies, the results of randomized controlled trials have been disappointing so far and do not corroborate the use of MPH as a substitute for cocaine dependence in patients without attention deficit hyperactivity disorder. Conclusion Clinical studies evaluating MPH substitution for cocaine dependence have provided inconsistent findings. However, the negative findings may be explained by specific study characteristics, among them dosing, duration of treatment, or sample size. This needs to be considered when discussing the potential of MPH as replacement therapy for cocaine dependence. Finally, based on the results, we suggest possible directions for future research.
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Affiliation(s)
- Kenneth M Dürsteler
- Center for Addictive Disorders, Psychiatric University Clinics Basel, Basel, Switzerland ; Center for Addictive Disorders, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - Eva-Maria Berger
- Center for Addictive Disorders, Psychiatric University Clinics Basel, Basel, Switzerland
| | - Johannes Strasser
- Center for Addictive Disorders, Psychiatric University Clinics Basel, Basel, Switzerland
| | - Carlo Caflisch
- Center for Addictive Disorders, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - Jochen Mutschler
- Center for Addictive Disorders, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - Marcus Herdener
- Center for Addictive Disorders, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - Marc Vogel
- Center for Addictive Disorders, Psychiatric University Clinics Basel, Basel, Switzerland
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14
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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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Stoops WW, Rush CR. Agonist replacement for stimulant dependence: a review of clinical research. Curr Pharm Des 2014; 19:7026-35. [PMID: 23574440 DOI: 10.2174/138161281940131209142843] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 04/04/2013] [Indexed: 11/22/2022]
Abstract
Stimulant use disorders are an unrelenting public health concern worldwide. Agonist replacement therapy is among the most effective strategies for managing substance use disorders including nicotine and opioid dependence. The present paper reviewed clinical data from human laboratory self-administration studies and clinical trials to determine whether agonist replacement therapy is a viable strategy for managing cocaine and/or amphetamine use disorders. The extant literature suggests that agonist replacement therapy may be effective for managing stimulant use disorders, however, the clinical selection of an agonist replacement medication likely needs to be based on the pharmacological mechanism of the medication and the stimulant abused by patients. Specifically, dopamine releasers appear most effective for reducing cocaine use whereas dopamine reuptake inhibitors appear most effective for reducing amphetamine use.
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Affiliation(s)
- William W Stoops
- Department of Behavioral Science, University of Kentucky Medical Center, Lexington, KY 40536- 0086.
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Calipari ES, Ferris MJ, Melchior JR, Bermejo K, Salahpour A, Roberts DCS, Jones SR. Methylphenidate and cocaine self-administration produce distinct dopamine terminal alterations. Addict Biol 2014; 19:145-55. [PMID: 22458761 DOI: 10.1111/j.1369-1600.2012.00456.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methylphenidate (MPH) is a commonly abused psychostimulant prescribed for the treatment of attention deficit hyperactivity disorder. MPH has a mechanism of action similar to cocaine (COC) and is commonly characterized as a dopamine transporter (DAT) blocker. While there has been extensive work aimed at understanding dopamine (DA) nerve terminal changes following COC self-administration, very little is known about the effects of MPH self-administration on the DA system. We used fast scan cyclic voltammetry in nucleus accumbens core slices from animals with a 5-day self-administration history of 40 injections/day of either MPH (0.56 mg/kg) or COC (1.5 mg/kg) to explore alterations in baseline DA release and uptake kinetics as well as alterations in the interaction of each compound with the DAT. Although MPH and COC have similar behavioral effects, the consequences of self-administration on DA system parameters were found to be divergent. We show that COC self-administration reduced DAT levels and maximal rates of DA uptake, as well as reducing electrically stimulated release, suggesting decreased DA terminal function. In contrast, MPH self-administration increased DAT levels, DA uptake rates and DA release, suggesting enhanced terminal function, which was supported by findings of increased metabolite/DA tissue content ratios. Tyrosine hydroxylase messenger RNA, protein and phosphorylation levels were also assessed in both groups. Additionally, COC self-administration reduced COC-induced DAT inhibition, while MPH self-administration increased MPH-induced DAT inhibition, suggesting opposite pharmacodynamic effects of these two drugs. These findings suggest that the factors governing DA system adaptations are more complicated than simple DA uptake blockade.
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Affiliation(s)
- Erin S Calipari
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, NC, USA Department of Pharmacology, University of Toronto, Toronto, Canada
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Effects of methcathinone and 3-Cl-methcathinone (PAL-434) in cocaine discrimination or self-administration in rhesus monkeys. Int J Neuropsychopharmacol 2013; 16:1985-98. [PMID: 23768644 DOI: 10.1017/s146114571300059x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Monoamine releasers with varying selectivity for dopamine (DA)/norepinephrine and serotonin (5-HT) release are potential treatment medications for cocaine abuse. Although DA-selective monoamine releasers effectively reduce cocaine abuse, their clinical usefulness is limited by abuse liability. It is hypothesized that increasing 5-HT neurotransmission may reduce the abuse-related effects of DA releasers, but the optimal DA:5-HT release ratio remains to be determined. This study in rhesus monkeys compared the effects of two compounds with differing potency for 5-HT release. Methcathinone and 3-Cl-methcathinone (PAL-434) have equal potency for DA release, but PAL-434 has 10-fold higher potency for 5-HT release. In drug discrimination studies, monkeys were trained to discriminate cocaine (0.4 mg/kg i.m.) from saline in a two-key, food-reinforced procedure. In drug self-administration studies, a separate group of monkeys was trained to respond for cocaine [0.01 mg/kg/injection (inj)] and food (1 g pellets) under a second order schedule of reinforcement [FR2(VR16:S)]. When responding was stable, methcathinone (0.1–0.56 mg/kg.h i.v.) or PAL-434 (0.32–1.8 mg/kg.h i.v.) was administered chronically (one injection every 20 min for 23 h/d) for 7–10 d. In discrimination studies, both compounds dose-dependently increased cocaine-like responding but with different potencies (cocaine=methcathinone >PAL-434). Chronic treatment with methcathinone or PAL-434 dose-dependently and selectively reduced cocaine self-administration. PAL-434 was about 4-fold and methcathinone about 1.6-fold more potent at decreasing cocaine- over food-maintained responding. These data suggest that compounds with moderate selectivity for DA vs. 5-HT release (8–15-fold) may be effective for the treatment of cocaine dependence.
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Hiranita T, Soto PL, Tanda G, Kopajtic TA, Katz JL. Stimulants as specific inducers of dopamine-independent σ agonist self-administration in rats. J Pharmacol Exp Ther 2013; 347:20-9. [PMID: 23908387 DOI: 10.1124/jpet.113.207522] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
A previous study showed that cocaine self-administration induced dopamine-independent reinforcing effects of σ agonists mediated by their selective actions at σ1 receptors (σ1Rs), which are intracellularly mobile chaperone proteins implicated in abuse-related effects of stimulants. The present study assessed whether the induction was specific to self-administration of cocaine. Rats were trained to self-administer the dopamine releaser, d-methamphetamine (0.01-0.32 mg/kg per injection), the μ-opioid receptor agonist, heroin (0.001-0.032 mg/kg per injection), and the noncompetitive N-methyl-d-aspartate receptor/channel antagonist ketamine (0.032-1.0 mg/kg per injection). As with cocaine, self-administration of d-methamphetamine induced reinforcing effects of the selective σ1R agonists PRE-084 [2-(4-morpholinethyl)1-phenylcyclohexanecarboxylate hydrochloride] and (+)-pentazocine (0.032-1.0 mg/kg per injection, each). In contrast, neither self-administration of heroin nor ketamine induced PRE-084 or (+)-pentazocine (0.032-10 mg/kg per injection, each) self-administration. Although the σ1R agonists did not maintain responding in subjects with histories of heroin or ketamine self-administration, substitution for those drugs was obtained with appropriate agonists (e.g., remifentanil, 0.1-3.2 µg/kg per injection, for heroin and (5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine ((+)-MK 801; dizocilpine), 0.32-10.0 µg/kg per injection, for ketamine). The σR antagonist N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)ethylamine dihydrobromide (BD 1008; 1.0-10 mg/kg) dose-dependently blocked PRE-084 self-administration but was inactive against d-methamphetamine, heroin, and ketamine. In contrast, PRE-084 self-administration was affected neither by the dopamine receptor antagonist (+)-butaclamol (10-100 μg/kg) nor by the opioid antagonist (-)-naltrexone (1.0-10 mg/kg), whereas these antagonists were active against d-methamphetamine and heroin self-administration, respectively. The results indicate that experience specifically with indirect-acting dopamine agonists induces reinforcing effects of previously inactive σ1R agonists. It is further suggested that induced σ1R reinforcing mechanisms may play an essential role in treatment-resistant stimulant abuse, suggesting new approaches for the development of effective medications for its treatment.
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Affiliation(s)
- Takato Hiranita
- Psychobiology Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland (T.H., G.T., T.A.K., J.L.K.); and Behavioral Biology Research Center, Johns Hopkins University School of Medicine, Baltimore, Maryland (P.L.S.)
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19
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Quisenberry AJ, Prisinzano T, Baker LE. Combined effects of modafinil and d-amphetamine in male Sprague-Dawley rats trained to discriminate d-amphetamine. Pharmacol Biochem Behav 2013; 110:208-15. [PMID: 23880213 DOI: 10.1016/j.pbb.2013.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 07/09/2013] [Accepted: 07/13/2013] [Indexed: 10/26/2022]
Abstract
Modafinil is a novel wake-promoting drug with FDA approval for the treatment of sleep-related disorders that has recently been investigated as a potential agonist replacement therapy for psychostimulant dependence. Previous research in animals and humans indicates modafinil has a lower abuse liability than traditional psychostimulants, although few studies have carefully assessed modafinil's stimulus properties in combination with other psychostimulants. The current study trained male Sprague-Dawley rats to discriminate subcutaneous injections of 0.3 mg/kg (n=8) or 1.0 mg/kg d-amphetamine (n=8) from saline under an FR 20 schedule of food reinforcement and substitution tests were administered with d-amphetamine (0.03-1.0 mg/kg, s.c.), modafinil (32-256 mg/kg, i.g.), and a low modafinil dose (32 mg/kg, i.g.) in combination with d-amphetamine (0.03-1.0 mg/kg, s.c.) to determine if these drugs have additive effects. The selective D2 dopamine agonist, PNU-91356A, was also tested as a positive control and ethanol and morphine were tested as negative controls. Results indicate that modafinil produced dose-dependent and statistically significant d-amphetamine-lever responding in both groups and nearly complete substitution in animals trained to discriminate 1.0 mg/kg d-amphetamine. Modafinil pretreatment slightly increased the discrimination of low d-amphetamine doses in animals trained to discriminate 0.3 mg/kg d-amphetamine. These results support previous findings that modafinil and d-amphetamine may have additive effects. In consideration of recent interests in modafinil as an agonist treatment for psychostimulant dependence, additional preclinical investigations utilizing other methodologies to examine modafinil in combination with other stimulants, such as behavioral sensitization paradigms or drug self-administration, may be of interest.
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Hiranita T, Mereu M, Soto PL, Tanda G, Katz JL. Self-administration of cocaine induces dopamine-independent self-administration of sigma agonists. Neuropsychopharmacology 2013; 38:605-15. [PMID: 23187725 PMCID: PMC3572457 DOI: 10.1038/npp.2012.224] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/11/2012] [Accepted: 10/14/2012] [Indexed: 11/09/2022]
Abstract
Sigma(1) receptors (σ(1)Rs) are intracellularly mobile chaperone proteins implicated in several disease processes, as well as psychiatric disorders and substance abuse. Here we report that although selective σ(1)R agonists (PRE-084, (+)-pentazocine) lacked reinforcing effects in drug-naive rats, over the course of 28 experimental sessions, which was more than sufficient for acquisition of cocaine self-administration, responding was not maintained by either σ(1)R agonist. In contrast, after subjects self-administered cocaine σ(1)R agonists were readily self-administered. The induced reinforcing effects were long lasting; a response for which subjects had no history of reinforcement was newly conditioned with both σ(1)R agonists, extinguished when injections were discontinued, and reconditioned when σ(1)R agonists again followed responses. Experience with food reinforcement was ineffective as an inducer of σ(1)R agonist reinforcement. Although a variety of dopamine receptor antagonists blocked cocaine self-administration, consistent with its dopaminergic mechanism, PRE-084 self-administration was entirely insensitive to these drugs. Conversely, the σR antagonist, BD1063, blocked PRE-084 self-administration but was inactive against cocaine. In microdialysis studies i.v. PRE-084 did not significantly stimulate dopamine at doses that were self-administered in rats either with or without a cocaine self-administration experience. The results indicate that cocaine experience induces reinforcing effects of previously inactive σ(1)R agonists, and that the mechanism underlying these reinforcing effects is dopamine independent. It is further suggested that induced σ(1)R mechanisms may have an essential role in treatment-resistant stimulant abuse, suggesting new approaches for the development of effective medications for stimulant abuse.
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Affiliation(s)
- Takato Hiranita
- Psychobiology Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Maddalena Mereu
- Psychobiology Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Paul L Soto
- Behavioral Biology Research Center, Johns Hopkins University Medical School, Baltimore, MD, USA
| | - Gianluigi Tanda
- Psychobiology Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Jonathan L Katz
- Psychobiology Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
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Li L, Hiranita T, Hayashi S, Newman AH, Katz JL. The stereotypy-inducing effects of N-substituted benztropine analogs alone and in combination with cocaine do not account for their blockade of cocaine self-administration. Psychopharmacology (Berl) 2013; 225:733-42. [PMID: 22975727 PMCID: PMC4472487 DOI: 10.1007/s00213-012-2862-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 08/22/2012] [Indexed: 11/24/2022]
Abstract
RATIONALE Previous studies have demonstrated that several N-substituted 4', 4″-diF-benztropine (BZT) analogs with high dopamine transporter affinity selectively decreased cocaine self-administration without affecting food-maintained behavior in rats. OBJECTIVES The present study examined if the decreases in cocaine self-administration are due to competition from excess behavioral activity (hyperlocomotion or stereotypy) induced by the BZT analogs alone or in combination with cocaine. RESULTS Pretreatments with the typical dopamine uptake inhibitor methylphenidate [1.0, 3.2, and 10 mg/kg, intraperitoneally (i.p.)] dose-dependently shifted the cocaine self-administration dose-effect curve (0, 0.032, 0.1, 0.32, and 1.0 mg/kg/injection) leftward. The shift in the dose-effect curve was obtained at doses of methylphenidate that, when administered alone, also decreased food-maintained behavior and increased locomotor activity and stereotypy. In contrast, the N-substituted BZT analogs, JHW 007 (1.0, 3.2, and 10 mg/kg, i.p.), AHN 1-055 (10 mg/kg), and, AHN 2-005 (10 mg/kg), as previously reported, decreased the maximum for the cocaine self-administration dose-effect curve, and did so at doses that were virtually without effects on food-maintained behavior. Further, the BZT analogs alone had minimal effects on locomotor activity and stereotypies and did not appreciably change the effects of cocaine on these measures when administered in combination with cocaine. CONCLUSIONS The present results suggest that the decrease in cocaine self-administration produced by the N-substituted BZT analogs is due to an antagonism of the reinforcing effects of cocaine rather than due to interference from competing behavioral overstimulation, and further supports the development of N-substituted BZT analogs as medications to treat cocaine abuse.
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Affiliation(s)
- Libin Li
- Psychobiology, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224
| | - Takato Hiranita
- Psychobiology, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224
| | - Shuichiro Hayashi
- Psychobiology, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224
| | - Amy H. Newman
- Medicinal Chemistry Sections, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224
| | - Jonathan L. Katz
- Psychobiology, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224
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Rush CR, Stoops WW. Agonist replacement therapy for cocaine dependence: a translational review. Future Med Chem 2012; 4:245-65. [PMID: 22300101 PMCID: PMC3292908 DOI: 10.4155/fmc.11.184] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cocaine use disorders are prevalent throughout the world. Agonist replacement therapy is among the most effective strategies for managing substance use disorders including nicotine and opioid dependence. This paper reviews the translational literature, including preclinical experiments, human laboratory studies and clinical trials, to determine whether agonist-replacement therapy is a viable strategy for managing cocaine dependence. Discussion is limited to transporter blockers (i.e., methylphenidate) and releasers (i.e., amphetamine analogs) that are available for use in humans in the hope of impacting clinical research and practice more quickly. The translational review suggests that agonist-replacement therapy, especially monoamine releasers, may be effective for managing cocaine dependence. Future directions for medications development are also discussed because the viability of agonist-replacement therapy for cocaine dependence may hinge on identifying novel compounds or formulations that have less abuse and diversion potential.
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Affiliation(s)
- Craig R Rush
- Department of Behavioral Science, University of Kentucky, College of Medicine, Medical Behavioral Science Building, Lexington, KY 40536-0086, USA.
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Kameyama M, Siqueira FA, Garcia-Mijares M, Silva LF, Silva MTA. Indatraline: synthesis and effect on the motor activity of Wistar rats. Molecules 2011; 16:9421-38. [PMID: 22075572 PMCID: PMC6264188 DOI: 10.3390/molecules16119421] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 11/03/2011] [Accepted: 11/07/2011] [Indexed: 11/20/2022] Open
Abstract
A new approach for the synthesis of indatraline was developed using as the key step an iodine(III)-mediated ring contraction of a 1,2-dihydronaphthalene derivative. Behavioral tests were conducted to evaluate the effect of indatraline and of its precursor indanamide on the motor activity of Wistar rats. Specific indexes for ambulation, raising and stereotypy were computed one, two and three hours after i.p. drug administration. Indatraline effects on motor activity lasted for at least three hours. On the other hand, no significant differences in motor activity were observed using indanamide. The results suggest that indatraline has a long lasting effect on motor activity and add evidence in favor of the potential use of that compound as a substitute in cocaine addiction.
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Affiliation(s)
- Márcia Kameyama
- Department of Experimental Psychology, Institute of Psychology, University of São Paulo, USP, Av. Prof. Mello de Moraes, 1721, Cidade Universitária, São Paulo SP CEP 05508-030, Brazil; (M.K.); (M.G.-M.)
| | - Fernanda A. Siqueira
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, CP 26077, São Paulo-SP, 05513-970, Brazil; (F.A.S.)
| | - Miriam Garcia-Mijares
- Department of Experimental Psychology, Institute of Psychology, University of São Paulo, USP, Av. Prof. Mello de Moraes, 1721, Cidade Universitária, São Paulo SP CEP 05508-030, Brazil; (M.K.); (M.G.-M.)
| | - Luiz F. Silva
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, CP 26077, São Paulo-SP, 05513-970, Brazil; (F.A.S.)
- Authors to whom correspondence should be addressed; (L.F.S.J.); (M.T.A.S.); Tel.: +55-11-3091-2388 (L.F.S.J.); Fax: +55-11-3815-5579 (L.F.S.J.)
| | - Maria T. A. Silva
- Department of Experimental Psychology, Institute of Psychology, University of São Paulo, USP, Av. Prof. Mello de Moraes, 1721, Cidade Universitária, São Paulo SP CEP 05508-030, Brazil; (M.K.); (M.G.-M.)
- Authors to whom correspondence should be addressed; (L.F.S.J.); (M.T.A.S.); Tel.: +55-11-3091-2388 (L.F.S.J.); Fax: +55-11-3815-5579 (L.F.S.J.)
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Awasaki Y, Nojima H, Nishida N. Application of the conditioned taste aversion paradigm to assess discriminative stimulus properties of psychostimulants in rats. Drug Alcohol Depend 2011; 118:288-94. [PMID: 21546172 DOI: 10.1016/j.drugalcdep.2011.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 04/06/2011] [Accepted: 04/07/2011] [Indexed: 10/18/2022]
Abstract
BACKGROUND The conditioned taste aversion (CTA) paradigm is one of the reliable methods to evaluate the discriminative stimulus properties of drugs and is characterized by a short conditioning period and no need for special equipment. This method, however, has not yet been fully investigated for psychostimulants such as cocaine and methamphetamine. METHODS In the present study, rats were trained to discriminate between cocaine and a vehicle using CTA and substitution tests with various psychostimulants were conducted to evaluate the usefulness of the method for assessing the discriminative stimulus properties of this pharmacological class. Male rats received an intraperitoneal (i.p.) injection of cocaine (10mg/kg) 10 min prior to access saccharin for 20-min, and immediately after the saccharin access they received an i.p. dose of LiCl (1.8 mEq; n=8, Group CL) or the vehicle (n=8, Group CW) on the day of conditioning; on the other days (2 or 3 days between the cocaine conditioning days), they were injected with saline prior to access to saccharin without the LiCl or vehicle injection after the access. RESULTS By the fifteenth cocaine conditioning trial, all animals acquired discrimination. In the substitution test, cocaine dose dependently decreased saccharin consumption. The psychostimulants, methamphetamine, methylphenidate, bupropion and sibutramine, substituted for cocaine, whereas the opioid μ agonist morphine and the cannabinoid agonist, Δ9-tetrahydrocannabinol, did not substitute for cocaine. Mazindol did not substitute for cocaine although it has CNS stimulant activities. CONCLUSION These results suggest that discriminative stimulus properties of psychostimulants can be evaluated using the CTA paradigm.
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Affiliation(s)
- Yasuyuki Awasaki
- Drug Safety Research Laboratories, Takeda Pharmaceutical Company Limited, 17-85, Jusohonmachi 2-chome, Yodogawa-ku, Osaka 532-8686, Japan.
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Matsumoto RR, Li SM, Katz JL, Fantegrossi WE, Coop A. Effects of the selective sigma receptor ligand, 1-(2-phenethyl)piperidine oxalate (AC927), on the behavioral and toxic effects of cocaine. Drug Alcohol Depend 2011; 118:40-7. [PMID: 21420799 PMCID: PMC3662542 DOI: 10.1016/j.drugalcdep.2011.02.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 12/11/2010] [Accepted: 02/20/2011] [Indexed: 12/14/2022]
Abstract
BACKGROUND Sigma receptors represent a unique structural class of proteins and they have become increasingly studied as viable medication development targets for neurological and psychiatric disorders, including drug abuse. Earlier studies have shown that cocaine and many other abused substances interact with sigma receptors and that antagonism of these proteins can mitigate their actions. METHODS In the present study, AC927 (1-(2-phenethyl)piperidine oxalate), a selective sigma receptor ligand, was tested against the behavioral and toxic effects of cocaine in laboratory animals. RESULTS Acute administration of AC927 in male, Swiss Webster mice significantly attenuated cocaine-induced convulsions, lethality, and locomotor activity, at doses that alone had no significant effects on behavior. Subchronic administration of AC927 also attenuated cocaine-induced conditioned place preference in mice, at doses that alone had no effects on place conditioning. In drug discrimination studies in male, Sprague-Dawley rats, AC927 partially substituted for the discriminative stimulus effects of cocaine. When it was administered with cocaine, AC927 shifted the cocaine dose-response curve to the left, suggesting an enhancement of the discriminative stimulus effects of cocaine. In non-human primates, AC927 was self-administered, maintaining responding that was intermediate between contingent saline and a maintenance dose of cocaine. CONCLUSION The ability of AC927 to elicit some cocaine-like appetitive properties and to also reduce many cocaine-induced behaviors suggests that it is a promising lead for the development of a medication to treat cocaine abuse.
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Affiliation(s)
- Rae R. Matsumoto
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center and Department of Basic Pharmaceutical Sciences, School of Pharmacy, West Virginia University,Corresponding author: Rae R. Matsumoto, Ph.D., West Virginia University, Department of Basic Pharmaceutical Sciences, School of Pharmacy, Morgantown, WV 26506. Tel.: +1 304 293 1450; fax: +1 304 293 2576.
| | - Su-Min Li
- Psychobiology Section, National Institute on Drug Abuse
| | | | - William E. Fantegrossi
- Department of Pharmacology, University of Michigan Medical School and Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences
| | - Andrew Coop
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland
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Hiranita T, Soto PL, Tanda G, Katz JL. Lack of cocaine-like discriminative-stimulus effects of σ-receptor agonists in rats. Behav Pharmacol 2011; 22:525-30. [PMID: 21808192 PMCID: PMC3666342 DOI: 10.1097/fbp.0b013e328349ab22] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Previous studies demonstrated the effectiveness of selective σ-receptor (σR) agonists [1,3-di-o-tolylguanidine (DTG), PRE-084] as reinforcers in rats trained to self-administer cocaine. Similar to cocaine, these drugs increased nucleus accumbens shell dopamine levels, and effects of DTG, but not PRE-084, on dopamine seemed to be mediated by σRs. In addition, σR antagonists blocked self-administration of σR agonists, but were inactive against reinforcing and neurochemical effects of cocaine. Thus, pharmacologically distinct mechanisms likely underlie the reinforcing and neurochemical effects of σR agonists and cocaine. This study further examined the cocaine-like effects of σR agonists in rats trained to discriminate injections of cocaine from saline to assess the similarity of their subjective effects. Standard dopamine-uptake inhibitors (WIN 35,428, methylphenidate), but neither σR agonist (PRE-084, DTG), produced full cocaine-like discriminative-stimulus effects. The lack of effects of σR agonists was obtained regardless of route of administration (intraperitoneal, subcutaneous, or intravenous) or pretreatment time (5 or 30 min before sessions). The present results demonstrate differences in the discriminative-stimulus effects of cocaine and selective σR agonists, indicating that an overlap of subjective effects is not necessary for σR agonist self-administration. The previously found differences in neurochemical effects of cocaine and σR agonists may contribute to their different subjective effects.
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Affiliation(s)
- Takato Hiranita
- Psychobiology Section, Medications Discovery Research Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224
- JSPS Research Fellowship for Japanese Biomedical and Behavioral Researchers at NIH
| | - Paul L. Soto
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University
| | - Gianluigi Tanda
- Psychobiology Section, Medications Discovery Research Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224
| | - Jonathan L. Katz
- Psychobiology Section, Medications Discovery Research Branch, Intramural Research Program, Department of Health and Human Services, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224
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Katz JL, Su TP, Hiranita T, Hayashi T, Tanda G, Kopajtic T, Tsai SY. A Role for Sigma Receptors in Stimulant Self Administration and Addiction. Pharmaceuticals (Basel) 2011; 4:880-914. [PMID: 21904468 PMCID: PMC3167211 DOI: 10.3390/ph4060880] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Sigma1 receptors (σ1Rs) represent a structurally unique class of intracellular proteins that function as chaperones. σ1Rs translocate from the mitochondria-associated membrane to the cell nucleus or cell membrane, and through protein-protein interactions influence several targets, including ion channels, G-protein-coupled receptors, lipids, and other signaling proteins. Several studies have demonstrated that σR antagonists block stimulant-induced behavioral effects, including ambulatory activity, sensitization, and acute toxicities. Curiously, the effects of stimulants have been blocked by σR antagonists tested under place-conditioning but not self-administration procedures, indicating fundamental differences in the mechanisms underlying these two effects. The self administration of σR agonists has been found in subjects previously trained to self administer cocaine. The reinforcing effects of the σR agonists were blocked by σR antagonists. Additionally, σR agonists were found to increase dopamine concentrations in the nucleus accumbens shell, a brain region considered important for the reinforcing effects of abused drugs. Although the effects of the σR agonist, DTG, on dopamine were obtained at doses that approximated those that maintained self administration behavior those of another agonist, PRE-084 required higher doses. The effects of DTG were antagonized by non-selective or a preferential σ2R antagonist but not by a preferential σ1R antagonist. The effects of PRE-084 on dopamine were insensitive to σR antagonists. The data suggest that the self administration of σR agonists is independent of dopamine and the findings are discussed in light of a hypothesis that cocaine has both intracellular actions mediated by σRs, as well as extracellular actions mediated through conventionally studied mechanisms. The co-activation and potential interactions among these mechanisms, in particular those involving the intracellular chaperone σRs, may lead to the pernicious addictive effects of stimulant drugs.
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Abstract
Methylphenidate (MPH) therapy for attention-deficit/hyperactivity disorder is common in children and adults. Concerns regarding abuse of MPH prompted studies to better understand its pharmacology. We used an established drug discrimination task to determine whether MPH could be discriminated by C57BL/6J (B6) mice. B6 mice learned to discriminate cues produced by racemic MPH (dl-MPH 5.0 mg/kg) or half the dose of pure d-isomer (2.5 mg/kg), and dose-response tests established appropriate reductions in discrimination with declining dose. Importantly, the two drug forms generalized to each other completely in substitution tests; consistent with reports that the l-isomer is pharmacodynamically inactive. An additional experiment indicated that lower doses (1 and 2 mg/kg) of dl-MPH did not support acquisition of MPH discrimination despite extensive training. Mice acquired discrimination of dl-MPH only when the dose was increased to 4 mg/kg. Thus, although these lower doses increased drug lever responding in mice trained on the higher dose, their stimuli were not sufficient to support acquisition of the discrimination task. These findings correspond to earlier studies conducted in our laboratory on threshold doses needed to produce stimulatory effects of motor activity in B6 mice. These preclinical findings provide insight into the relative potency, and by extension, efficacy of dl-MPH versus d-MPH doses.
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Herin DV, Rush CR, Grabowski J. Agonist-like pharmacotherapy for stimulant dependence: preclinical, human laboratory, and clinical studies. Ann N Y Acad Sci 2010; 1187:76-100. [PMID: 20201847 DOI: 10.1111/j.1749-6632.2009.05145.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A variety of natural and synthetic agents have long been used for stimulant properties, with nontherapeutic use producing multiple waves of stimulant abuse and dependence. The multitude of effects of stimulants exist on continua, and accordingly, here we characterize stimulant abuse/dependence and candidate pharmacotherapies in this manner. Behavioral therapy and medications have been investigated for treatment of stimulant abuse/dependence. Effectiveness of some behavioral interventions has been demonstrated. Most medications studied have been found to lack efficacy. However, an expanding literature supports use of agonist-like medications to treat stimulant abuse/dependence, a strategy effective for nicotine and opiate dependence. The agonist-like conceptualization for stimulant dependence posits that medications with properties similar to that of the abused drug, but possessing lesser abuse liability, will normalize neurochemistry and stabilize behavior, thus reducing drug use. Data suggest use of a range of medications, from l-dopa/carbidopa to amphetamine preparations, depending on the severity of use. This report reviews preclinical, human laboratory, and clinical trial data supporting the agonist-like approach, including risks and benefits. Future directions for development of agonist-like medications are also discussed.
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Affiliation(s)
- David V Herin
- Department of Psychiatry, University of Minnesota, Minneapolis, Minnesota, USA
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Influence of conditioned reinforcement on the response-maintaining effects of quinpirole in rats. Behav Pharmacol 2009; 20:492-504. [PMID: 19696656 DOI: 10.1097/fbp.0b013e328330ad9b] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
D2-like agonists, such as quinpirole, maintain responding in monkeys, rats, and mice when they are substituted for cocaine. This study examined the influence of operant history and cocaine-paired stimuli (CS) on quinpirole-maintained responding in rats trained to nose poke for cocaine. Upon acquisition of responding for cocaine, substitutions were performed in the presence or absence of injection-CS pairings. Although cocaine maintained responding regardless of whether injections were accompanied by CS, quinpirole maintained responding only when CS were paired with injections. To assess the influence of operant history, injections of cocaine, quinpirole, remifentanil, nicotine, or saline were made available on a previously inactive lever, while nose pokes continued to result in CS presentation. Although responding was reallocated from the nose poke to the lever when cocaine or remifentanil was available, lever presses remained low, and nose poking persisted when quinpirole or nicotine was made contingent upon lever presses. Finally, quinpirole pretreatments resulted in high rates of nose poking when nose pokes resulted in CS presentation alone, but failed to maintain nose poking when the CS was omitted. Taken together, these results suggest that the response-maintaining effects of quinpirole are primarily mediated by an enhancement of the conditioned reinforcing effects of earlier CS, rather than by a reinforcing effect of quinpirole.
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Chiodo KA, Roberts DC. Decreased reinforcing effects of cocaine following 2 weeks of continuous D-amphetamine treatment in rats. Psychopharmacology (Berl) 2009; 206:447-56. [PMID: 19652955 PMCID: PMC2770337 DOI: 10.1007/s00213-009-1622-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Accepted: 07/11/2009] [Indexed: 12/31/2022]
Abstract
RATIONALE Recent studies have investigated D-amphetamine as a potential agonist medication for cocaine dependence. In rats, a 14-day continuous infusion of D: -amphetamine via osmotic mini-pump has been shown to decrease cocaine-reinforced responding under a progressive ratio (PR) schedule of reinforcement. OBJECTIVES This study was designed to assess the influences of the D-amphetamine treatment dose and self-administered cocaine dose on the magnitude of this effect. MATERIALS AND METHODS Experiment 1: rats were trained to self-administer 1.5 mg/kg/inj cocaine under a PR schedule, then implanted with D-amphetamine mini-pumps for 14 days (days 1-7, 5 mg/kg/day; days 8-14, 7.5 mg/kg/day). Breakpoints were evaluated throughout the treatment period and 14 days post-treatment. Experiment 2: rats were trained to self-administer cocaine under a PR schedule and initial dose-response curves were determined before implantation of D-amphetamine mini-pumps. During the 14-day D-amphetamine (5 mg/kg/day) treatment period, rats self-administered one of four cocaine doses (0.19, 0.38, 0.75, or 1.5 mg/kg/inj). A post-treatment PR dose-response curve and responding under a fixed ratio 1 (FR1) schedule were evaluated after mini-pump removal. RESULTS Experiment 1: breakpoints for 1.5 mg/kg/inj cocaine were unchanged by the increasing dose of D-amphetamine. Experiment 2: the PR dose-response curve was shifted downward after the treatment period in rats that had self-administered 0.19 and 0.38 mg/kg/inj cocaine. In contrast, rats in the 0.75 and 1.5 mg/kg/inj groups demonstrated increased rates of cocaine intake under an FR1 schedule after the treatment period. CONCLUSIONS These data suggest that continuous D-amphetamine treatment attenuates the reinforcing effects of cocaine.
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Affiliation(s)
- Keri A. Chiodo
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina, 27157
- Neuroscience Program, Wake Forest University School of Medicine, Winston-Salem, North Carolina, 27157
| | - David C.S. Roberts
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, North Carolina, 27157
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Tanda G, Newman AH, Ebbs AL, Tronci V, Green JL, Tallarida RJ, Katz JL. Combinations of cocaine with other dopamine uptake inhibitors: assessment of additivity. J Pharmacol Exp Ther 2009; 330:802-9. [PMID: 19483071 DOI: 10.1124/jpet.109.154302] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Drugs that inhibit dopamine (DA) reuptake through actions at the dopamine transporter (DAT) have been proposed as candidates for development as pharmacotherapies for cocaine abuse. Accordingly, it is important to understand the potential pharmacological interactions of cocaine with other drugs acting at the DAT. Effects of combinations of cocaine with a cocaine analog, 2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane (WIN 35,428), were compared quantitatively with the combinations of cocaine with the N-butyl,4',4''-diF benztropine analog, 3-(bis(4-fluorophenyl)methoxy)-8-butyl-8-azabicyclo[3.2.1]octane (JHW 007), to determine whether their effects on DA levels in the shell of the nucleus accumbens (NAC) in mice differed. Each of the drugs alone produced dose-related elevations in NAC DA levels. In contrast to the other drugs, JHW 007 was less effective, producing maximal effects that approached 400% of control versus approximately 700% with the other drugs. In addition, the JHW 007 dose-effect curve was not as steep as those for cocaine and WIN 35,428. Combinations of cocaine with its analog, WIN 35,428, were most often greater than those predicted based on dose additivity. In contrast, combinations of cocaine with JHW 007 were most often subadditive. This outcome is consistent with recent studies suggesting that structurally divergent DA uptake inhibitors bind to different domains of the DAT, which can result in different DAT conformations. The conformational changes occurring with JHW 007 binding may result in functional outcomes that alter its abuse liability and its effects in combination with cocaine.
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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., Baltimore, MD 21224, USA
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Cocaine self-administration reinforced on a progressive ratio schedule decreases with continuous D-amphetamine treatment in rats. Psychopharmacology (Berl) 2008; 200:465-73. [PMID: 18604521 PMCID: PMC2735185 DOI: 10.1007/s00213-008-1222-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Accepted: 05/31/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE To date, there is no medication specifically approved for cocaine addiction. Agonist medications are used clinically in the treatment of other addictions, which suggests that this method of drug therapy could potentially be successful in treating cocaine addiction as well. OBJECTIVE The objective of this study was to determine the effect of extended D-amphetamine treatment on responding on a progressive ratio (PR) schedule reinforced by cocaine. MATERIALS AND METHODS Rats were trained to self-administer cocaine (0.19, 0.38, 0.75, or 1.5 mg/kg/injection) or food on a PR schedule. After stable baseline breakpoints (the number of reinforcers earned in one session) were established over 3 days, animals were implanted with osmotic mini-pumps that continuously delivered D-amphetamine (5 mg/kg/day) for a duration of either 7 or 14 days. Breakpoints were then determined during and/or after this treatment period. RESULTS Rats demonstrated dose-dependent decreases in cocaine-reinforced responding over the D-amphetamine treatment period. Breakpoints for doses of 0.75 mg/kg/injection and below decreased significantly when compared to baseline and remained decreased for up to 14 days after mini-pump removal, whereas those for the highest dose of cocaine remained unchanged. Additionally, D-amphetamine treatment during a 14-day abstinence period from cocaine self-administration had no effect on breakpoints when tested the day after mini-pump removal. CONCLUSIONS These data suggest that the reduction in cocaine-reinforced responding after continuous D-amphetamine treatment cannot be accounted for by tolerance alone. Instead, the roles of learning and the interaction between cocaine and D-amphetamine must be considered and examined in future studies.
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Schmitt KC, Zhen J, Kharkar P, Mishra M, Chen N, Dutta AK, Reith MEA. Interaction of cocaine-, benztropine-, and GBR12909-like compounds with wild-type and mutant human dopamine transporters: molecular features that differentially determine antagonist-binding properties. J Neurochem 2008; 107:928-40. [PMID: 18786172 DOI: 10.1111/j.1471-4159.2008.05667.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The widely abused psychostimulant cocaine is thought to elicit its reinforcing effects primarily via inhibition of the neuronal dopamine transporter (DAT). However, not all DAT inhibitors share cocaine's behavioral profile, despite similar or greater affinity for the DAT. This may be due to differential molecular interactions with the DAT. Our previous work using transporter mutants with altered conformational equilibrium (W84L and D313N) indicated that benztropine and GBR12909 interact with the DAT in a different manner than cocaine. Here, we expand upon these previous findings, studying a number of structurally different DAT inhibitors for their ability to inhibit [(3)H]CFT binding to wild-type, W84L and D313N transporters. We systematically tested structural intermediates between cocaine and benztropine, structural hybrids of benztropine and GBR12909 and a number of other structurally heterologous inhibitors. Derivatives of the stimulant desoxypipradrol (2-benzhydrylpiperidine) exhibited a cocaine-like binding profile with respect to mutation, whereas compounds possessing the diphenylmethoxy moiety of benztropine and GBR12909 were dissimilar to cocaine-like compounds. In tests with specific isomers of cocaine and tropane analogues, compounds with 3alpha stereochemistry tended to exhibit benztropine-like binding, whereas those with 3beta stereochemistry were more cocaine-like. Our results point to the importance of specific molecular features--most notably the presence of a diphenylmethoxy moiety--in determining a compound's binding profile. This study furthers the concept of using DAT mutants to differentiate cocaine-like inhibitors from atypical inhibitors in vitro. Further studies of the molecular features that define inhibitor-transporter interaction could lead to the development of DAT inhibitors with differential clinical utility.
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Affiliation(s)
- Kyle C Schmitt
- Department of Psychiatry, New York University School of Medicine, New York, New York, USA
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Pharmacology of stimulants prohibited by the World Anti-Doping Agency (WADA). Br J Pharmacol 2008; 154:606-22. [PMID: 18500382 DOI: 10.1038/bjp.2008.124] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
This review examines the pharmacology of stimulants prohibited by the World Anti-Doping Agency (WADA). Stimulants that increase alertness/reduce fatigue or activate the cardiovascular system can include drugs like ephedrine available in many over-the-counter medicines. Others such as amphetamines, cocaine and hallucinogenic drugs, available on prescription or illegally, can modify mood. A total of 62 stimulants (61 chemical entities) are listed in the WADA List, prohibited in competition. Athletes may have stimulants in their body for one of three main reasons: inadvertent consumption in a propriety medicine; deliberate consumption for misuse as a recreational drug and deliberate consumption to enhance performance. The majority of stimulants on the list act on the monoaminergic systems: adrenergic (sympathetic, transmitter noradrenaline), dopaminergic (transmitter dopamine) and serotonergic (transmitter serotonin, 5-HT). Sympathomimetic describes agents, which mimic sympathetic responses, and dopaminomimetic and serotoninomimetic can be used to describe actions on the dopamine and serotonin systems. However, many agents act to mimic more than one of these monoamines, so that a collective term of monoaminomimetic may be useful. Monoaminomimietic actions of stimulants can include blockade of re-uptake of neurotransmitter, indirect release of neurotransmitter, direct activation of monoaminergic receptors. Many of the stimulants are amphetamines or amphetamine derivatives, including agents with abuse potential as recreational drugs. A number of agents are metabolized to amphetamine or metamphetamine. In addition to the monoaminomimetic agents, a small number of agents with different modes of action are on the list. A number of commonly used stimulants are not considered as Prohibited Substances.
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Feyissa AM, Kelly JP. A review of the neuropharmacological properties of khat. Prog Neuropsychopharmacol Biol Psychiatry 2008; 32:1147-66. [PMID: 18561890 DOI: 10.1016/j.pnpbp.2007.12.033] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Revised: 12/21/2007] [Accepted: 12/23/2007] [Indexed: 10/22/2022]
Abstract
BACKGROUND The psychostimulant khat (Catha edulis Forsk), is a herbal drug cultivated and chewed as a recreational and socializing drug in East Africa and the Arabian Peninsula for centuries. Due to increasing air transportation and the loosening of customs restrictions, it is now readily available in the Western Countries mainly used by immigrants from khat growing areas causing a concern to policy-makers. OBJECTIVE We conducted this review to further gain an insight to the neuropharmacological effects of khat. METHODOLOGY PubMed search engine with key terms 'khat' or 'qat' or 'mirra' or'qaad/jaad' or 'cathinone' was used to obtain articles relevant to khat chewing. In total 284 English written articles published from 1959 to 2007 were screened. RESULTS Most of the studies focused on cathinone, the postulated active psychostimulant alkaloid in khat. There were few studies which investigated the entire plant extract in either in vitro or animal studies. In the majority of the studies it was reported that both cathinone and cathine, another psychoactive constituent, have actions that are similar to those of amphetamine. CONCLUSIONS It seems that the well investigated khat alkaloids have many features similar to amphetamines; however there is a need for a more thorough examination of khat itself in well designed in vitro, animal and human studies with a range of comparator drugs before confirming the claim that khat is a "natural amphetamine".
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Affiliation(s)
- Anteneh M Feyissa
- Department of Pharmacology and Therapeutics, NUI Galway, Galway, Ireland
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