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Heifets BD, Olson DE. Therapeutic mechanisms of psychedelics and entactogens. Neuropsychopharmacology 2024; 49:104-118. [PMID: 37488282 PMCID: PMC10700553 DOI: 10.1038/s41386-023-01666-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 07/10/2023] [Accepted: 07/11/2023] [Indexed: 07/26/2023]
Abstract
Recent clinical and preclinical evidence suggests that psychedelics and entactogens may produce both rapid and sustained therapeutic effects across several indications. Currently, there is a disconnect between how these compounds are used in the clinic and how they are studied in preclinical species, which has led to a gap in our mechanistic understanding of how these compounds might positively impact mental health. Human studies have emphasized extra-pharmacological factors that could modulate psychedelic-induced therapeutic responses including set, setting, and integration-factors that are poorly modelled in current animal experiments. In contrast, animal studies have focused on changes in neuronal activation and structural plasticity-outcomes that are challenging to measure in humans. Here, we describe several hypotheses that might explain how psychedelics rescue neuropsychiatric disease symptoms, and we propose ways to bridge the gap between human and rodent studies. Given the diverse pharmacological profiles of psychedelics and entactogens, we suggest that their rapid and sustained therapeutic mechanisms of action might best be described by the collection of circuits that they modulate rather than their actions at any single molecular target. Thus, approaches focusing on selective circuit modulation of behavioral phenotypes might prove more fruitful than target-based methods for identifying novel compounds with rapid and sustained therapeutic effects similar to psychedelics and entactogens.
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Affiliation(s)
- Boris D Heifets
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, 94305, USA.
| | - David E Olson
- Institute for Psychedelics and Neurotherapeutics, University of California, Davis, Davis, CA, 95616, USA.
- Department of Chemistry, University of California, Davis, Davis, CA, 95616, USA.
- Center for Neuroscience, University of California, Davis, Davis, CA, 95618, USA.
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Sacramento, CA, 95817, USA.
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Baird TR, Karin KN, Marsh SA, Carroll FI, Medina-Contreras JML, Negus SS, Eltit JM. Rate of onset of dopamine transporter inhibitors assessed with intracranial self-stimulation and in vivo dopamine photometry in rats. Psychopharmacology (Berl) 2023; 240:969-981. [PMID: 36802016 PMCID: PMC10466267 DOI: 10.1007/s00213-023-06340-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 02/09/2023] [Indexed: 02/23/2023]
Abstract
Drug self-administration and intracranial self-stimulation (ICSS) are two preclinical behavioral procedures used to predict abuse potential of drugs, and abuse-related drug effects in both procedures are thought to depend on increased mesolimbic dopamine (DA) signaling. Drug self-administration and ICSS yield concordant metrics of abuse potential across a diverse range of drug mechanisms of action. The "rate of onset," defined as the velocity with which a drug produces its effect once administered, has also been implicated as a determinant of abuse-related drug effects in self-administration procedures, but this variable has not been systematically examined in ICSS. Accordingly, this study compared ICSS effects produced in rats by three DA transporter inhibitors that have different rates of onset (fastest to slowest: cocaine, WIN-35428, RTI-31) and that produced progressively weaker metrics of abuse potential in a drug self-administration procedure in rhesus monkeys. Additionally, in vivo photometry using the fluorescent DA sensor dLight1.1 targeted to the nucleus accumbens (NAc) was used to assess the time course of extracellular DA levels as a neurochemical correlate of behavioral effects. All three compounds produced ICSS facilitation and increased DA levels assessed by dLight. In both procedures, the rank order of onset rate was cocaine > WIN-35428 > RTI-31; however, in contrast to monkey drug self-administration results, maximum effects did not differ across compounds. These results provide additional evidence that drug-induced increases in DA drive ICSS facilitation in rats and illustrate the utility of both ICSS and photometry to evaluate the time course and magnitude of abuse-related drug effects in rats.
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Affiliation(s)
- Tyson R Baird
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA, 23298, USA
- Integrative Life Sciences Doctoral Program, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Kimberly N Karin
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Samuel A Marsh
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - F Ivy Carroll
- Research Triangle Institute, Research Triangle Park, Durham, NC, 27709, USA
| | - J M L Medina-Contreras
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, 1101 E. Marshall Street, 3-038H, Richmond, VA, 23298, USA
| | - S Stevens Negus
- Department of Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Jose M Eltit
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, 1101 E. Marshall Street, 3-038H, Richmond, VA, 23298, USA.
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Relative reinforcing effects of dibutylone, ethylone, and N-ethylpentylone: self-administration and behavioral economics analysis in rats. Psychopharmacology (Berl) 2022; 239:2875-2884. [PMID: 35716192 DOI: 10.1007/s00213-022-06173-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 06/06/2022] [Indexed: 01/23/2023]
Abstract
RATIONALE Following the emergence of methylone as one of the most popular synthetic cathinones, this group of novel psychoactive substance with names ending in "-lone," such as dibutylone, ethylone, and N-ethylpentylone, appeared on the recreational drug market. The pharmacological mechanisms of dibutylone, ethylone, and N-ethylpentylone are well understood; however, to date, the reinforcing effects of dibutylone, ethylone, and N-ethylpentylone are still unclear. OBJECTIVES This study aimed to examine the self-administration of dibutylone, ethylone, and N-ethylpentylone relative to methamphetamine (METH) and to quantify their relative reinforcing effectiveness using behavioral economic analysis. METHODS Male Sprague-Dawley rats were trained to self-administer METH (0.05 mg/kg) under a fixed-ratio 1 (FR1) schedule. Following the training, dose substitution was used to generate full dose-response curves for METH and the three synthetic cathinones. According to the first doses on the descending limb of the dose-response curves, rats were trained to self-administer METH (0.05 mg/kg), dibutylone (0.1 mg·kg-1·infusion-1), ethylone (0.4 mg·kg-1·infusion-1), or N-ethylpentylone (0.1 mg·kg-1·infusion-1) under an FR1 schedule, and a behavioral economic evaluation of their reinforcing effectiveness was then performed. RESULTS Dibutylone, ethylone, and N-ethylpentylone functioned as reinforcers, and the inverted U-shaped dose-response curves were obtained. The rank order of reinforcing potency in this procedure was METH > N-ethylpentylone ≈ dibutylone > ethylone. In the economic analysis, the comparisons of the essential value (EV) transformed from demand elasticity (α) indicated that the rank order of efficacy as reinforcers was METH (EV = 7.93) ≈ dibutylone (EV = 7.81) > N-ethylpentylone (EV = 5.21) ≈ ethylone (EV = 4.19). CONCLUSIONS These findings demonstrated that dibutylone, ethylone, and N-ethylpentylone function as reinforcers and have addictive potential, suggesting that the modification of α-alkyl and N-alkyl side chains may affect their reinforcing efficacy.
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Ding H, Trapella C, Kiguchi N, Hsu FC, Caló G, Ko MC. Functional Profile of Systemic and Intrathecal Cebranopadol in Nonhuman Primates. Anesthesiology 2021; 135:482-493. [PMID: 34237134 PMCID: PMC8446297 DOI: 10.1097/aln.0000000000003848] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND Cebranopadol, a mixed nociceptin/opioid receptor full agonist, can effectively relieve pain in rodents and humans. However, it is unclear to what degree different opioid receptor subtypes contribute to its antinociception and whether cebranopadol lacks acute opioid-associated side effects in primates. The authors hypothesized that coactivation of nociceptin receptors and μ receptors produces analgesia with reduced side effects in nonhuman primates. METHODS The antinociceptive, reinforcing, respiratory-depressant, and pruritic effects of cebranopadol in adult rhesus monkeys (n = 22) were compared with μ receptor agonists fentanyl and morphine using assays, including acute thermal nociception, IV drug self-administration, telemetric measurement of respiratory function, and itch-scratching responses. RESULTS Subcutaneous cebranopadol (ED50, 2.9 [95% CI, 1.8 to 4.6] μg/kg) potently produced antinociception compared to fentanyl (15.8 [14.6 to 17.1] μg/kg). Pretreatment with antagonists selective for nociceptin and μ receptors, but not δ and κ receptor antagonists, caused rightward shifts of the antinociceptive dose-response curve of cebranopadol with dose ratios of 2 and 9, respectively. Cebranopadol produced reinforcing effects comparable to fentanyl, but with decreased reinforcing strength, i.e., cebranopadol (mean ± SD, 7 ± 3 injections) versus fentanyl (12 ± 3 injections) determined by a progressive-ratio schedule of reinforcement. Unlike fentanyl (8 ± 2 breaths/min), systemic cebranopadol at higher doses did not decrease the respiratory rate (17 ± 2 breaths/min). Intrathecal cebranopadol (1 μg) exerted full antinociception with minimal scratching responses (231 ± 137 scratches) in contrast to intrathecal morphine (30 μg; 3,009 ± 1,474 scratches). CONCLUSIONS In nonhuman primates, the μ receptor mainly contributed to cebranopadol-induced antinociception. Similar to nociceptin/μ receptor partial agonists, cebranopadol displayed reduced side effects, such as a lack of respiratory depression and pruritus. Although cebranopadol showed reduced reinforcing strength, its detectable reinforcing effects and strength warrant caution, which is critical for the development and clinical use of cebranopadol. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Huiping Ding
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Claudio Trapella
- Department of Chemical and Pharmaceutical Sciences and LTTA, University of Ferrara, Ferrara, Italy
| | - Norikazu Kiguchi
- Department of Physiological Sciences, School of Pharmaceutical Sciences, Wakayama Medical University, Wakayama 640-8156, Japan
| | - Fang-Chi Hsu
- Department of Biostatistics and Data Science, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Girolamo Caló
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
| | - Mei-Chuan Ko
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
- W.G. Hefner Veterans Affairs Medical Center, Salisbury, North Carolina, USA
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Schenk S, Highgate Q. Methylenedioxymethamphetamine (MDMA): Serotonergic and dopaminergic mechanisms related to its use and misuse. J Neurochem 2021; 157:1714-1724. [PMID: 33711169 DOI: 10.1111/jnc.15348] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 12/21/2022]
Abstract
Methylenedioxymethamphetamine (MDMA) is an amphetamine analogue that preferentially stimulates the release of serotonin (5HT) and results in relatively small increases in synaptic dopamine (DA). The ratio of drug-stimulated increases in synaptic DA, relative to 5HT, predicts the abuse liability; drugs with higher DA:5HT ratios are more likely to be abused. Nonetheless, MDMA is a drug that is misused. Clinical and preclinical studies have suggested that repeated MDMA exposure produces neuroadaptive responses in both 5HT and DA neurotransmission that might explain the development and maintenance of MDMA self-administration in some laboratory animals and the development of a substance use disorder in some humans. In this paper, we describe the research that has demonstrated an inhibitory effect of 5HT on the acquisition of MDMA self-administration and the critical role of DA in the maintenance of MDMA self-administration in laboratory animals. We then describe the circuitry and 5HT receptors that are positioned to modulate DA activity and review the limited research on the effects of MDMA exposure on these receptor mechanisms.
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Affiliation(s)
- Susan Schenk
- School of Psychology, Victoria University of Wellington, Wellington, New Zealand
| | - Quenten Highgate
- School of Psychology, Victoria University of Wellington, Wellington, New Zealand
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Ding H, Kiguchi N, Perrey DA, Nguyen T, Czoty PW, Hsu FC, Zhang Y, Ko MC. Antinociceptive, reinforcing, and pruritic effects of the G-protein signalling-biased mu opioid receptor agonist PZM21 in non-human primates. Br J Anaesth 2020; 125:596-604. [PMID: 32819621 DOI: 10.1016/j.bja.2020.06.057] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 06/05/2020] [Accepted: 06/15/2020] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND A novel G-protein signalling-biased mu opioid peptide (MOP) receptor agonist, PZM21, was recently developed with a distinct chemical structure. It is a potent Gi/o activator with minimal β-arrestin-2 recruitment. Despite intriguing activity in rodent models, PZM21 function in non-human primates is unknown. The aim of this study was to investigate PZM21 actions after systemic or intrathecal administration in primates. METHODS Antinociceptive, reinforcing, and pruritic effects of PZM21 were compared with those of the clinically used MOP receptor agonists oxycodone and morphine in assays of acute thermal nociception, capsaicin-induced thermal allodynia, itch scratching responses, and drug self-administration in gonadally intact, adult rhesus macaques (10 males, six females). RESULTS After subcutaneous administration, PZM21 (1.0-6.0 mg kg-1) and oxycodone (0.1-0.6 mg kg-1) induced dose-dependent thermal antinociceptive effects (P<0.05); PZM21 was 10 times less potent than oxycodone. PZM21 exerted oxycodone-like reinforcing effects and strength as determined by two operant schedules of reinforcement in the intravenous drug self-administration assay. After intrathecal administration, PZM21 (0.03-0.3 mg) dose-dependently attenuated capsaicin-induced thermal allodynia (P<0.05). Although intrathecal PZM21 and morphine induced MOP receptor-mediated antiallodynic effects, both compounds induced robust, long-lasting itch scratching. CONCLUSIONS PZM21 induced antinociceptive, reinforcing, and pruritic effects similar to clinically used MOP receptor agonists in primates. Although structure-based discovery of PZM21 identified a novel avenue for studying G-protein signalling-biased ligands, biasing an agonist towards G-protein signalling pathways did not determine or alter reinforcing (i.e. abuse potential) or pruritic effects of MOP receptor agonists in a translationally relevant non-human primate model.
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Affiliation(s)
- Huiping Ding
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Norikazu Kiguchi
- Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - David A Perrey
- Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, NC, USA
| | - Thuy Nguyen
- Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, NC, USA
| | - Paul W Czoty
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Fang-Chi Hsu
- Department of Biostatistics and Data Science, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Yanan Zhang
- Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, NC, USA.
| | - Mei-Chuan Ko
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA; W.G. Hefner Veterans Affairs Medical Center, Salisbury, NC, USA.
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Dolan SB, Johnson MW. The drug purity discounting task: Ecstasy use likelihood is reduced by probabilistic impurity according to harmfulness of adulterants. Drug Alcohol Depend 2020; 208:107772. [PMID: 31974022 PMCID: PMC7156028 DOI: 10.1016/j.drugalcdep.2019.107772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/28/2019] [Accepted: 11/21/2019] [Indexed: 11/20/2022]
Abstract
BACKGROUND Ecstasy typically contains adulterants in addition to, or in lieu of, MDMA which may pose a greater risk to users than MDMA itself. The current study aimed to evaluate the effectiveness of adulterant-related informational prompts in reducing Ecstasy use using a novel probability discounting task. METHODS An online sample of past-month Ecstasy users (N = 278) were randomized to one of four different framing prompt conditions: no prompt; a prompt describing MDMA's effects; a prompt describing adulterants as inert "filler"; or a prompt describing adulterants as pharmacologically-active, potentially-harmful compounds. Each prompt contained general, potential public-health information that was not specifically related to subsequent behavioral tasks. All participants then completed an identical Drug Purity Discounting Task, in which they indicated the likelihood of using a sample of Ecstasy across different probabilities of the sample being impure, and then completed a hypothetical Ecstasy purchasing task. RESULTS Likelihood of Ecstasy use decreased as impurity probability increased across conditions. Ecstasy use likelihood was highest in the "inert" prompt condition, whereas pharmacologically-active adulterant or adulterant-nonspecific prompts resulted in comparably low likelihood of use. Ecstasy-use likelihood did not differ among conditions when the likelihood of sample impurity was 0. Ecstasy purchasing did not differ among groups. Inelastic purchasing was associated with greater likelihood of using potentially-impure Ecstasy. CONCLUSIONS Altogether, these data highlight the necessity of education regarding pharmacologically-active, rather than inert, adulterants in Ecstasy, and suggest that increased access to drug checking kits and services may mitigate some of the harms associated with Ecstasy use.
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Affiliation(s)
- Sean B Dolan
- Behavioral Pharmacology Research Unit, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Dr., Baltimore, MD 21224, USA.
| | - Matthew W Johnson
- Behavioral Pharmacology Research Unit, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, 5510 Nathan Shock Dr., Baltimore, MD 21224, USA.
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Stereoselective effects of the second-generation synthetic cathinone α-pyrrolidinopentiophenone (α-PVP): assessments of conditioned taste avoidance in rats. Psychopharmacology (Berl) 2019; 236:1067-1077. [PMID: 30334086 PMCID: PMC8328279 DOI: 10.1007/s00213-018-5070-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 10/04/2018] [Indexed: 12/19/2022]
Abstract
RATIONALE Work with α-pyrrolidinopentiophenone (α-PVP), a second-generation synthetic cathinone, has been generally limited to the racemate. Given that with other synthetic cathinones, there are behavioral and neurochemical differences between their enantiomers, differences may also be seen with α-PVP. OBJECTIVES The present study assessed the relative contribution of each enantiomer to the aversive effects of racemic-α-PVP by comparing their ability to induce a conditioned taste avoidance. METHODS Adult male Sprague-Dawley rats were exposed every other day for four exposures to a novel saccharin solution followed immediately by an injection of 0 (saline vehicle) or 1.5, 3, or 6 mg/kg of S-, R-, or racemic-α-PVP (IP). On alternating days, all subjects were given access to water to assess any unconditioned effects of α-PVP on general fluid consumption. RESULTS Rats injected with the racemate and S-isomer of α-PVP displayed avoidance of the drug-associated saccharin solution, although this avoidance was dose-dependent only for the subjects injected with the racemate. There was no evidence of taste avoidance in animals injected with the R-enantiomer at any dose tested. Animals injected with 3 mg/kg racemic-α-PVP did not differ in avoidance from those treated with 1.5 mg/kg of the S-enantiomer, but subjects treated with 6 mg/kg racemic-α-PVP displayed a significantly stronger avoidance than those treated with 3 mg/kg S-α-PVP. CONCLUSIONS The present work suggests that the aversive effects of racemic α-PVP are mediated primarily by its S-isomer. The fact that at the highest dose tested (6 mg/kg), the racemate induces an avoidance greater than the simple additive effects of the S- and R-isomers (at 3 mg/kg) suggests that while the R-isomer may not induce taste avoidance at this dose, it may interact synergistically with the S-isomer in mediating the effects of the racemic mixture. These results were discussed in terms of similar effects with other behavioral and physiological endpoints reported with a number of psychostimulants and suggest that the enantiomers of α-PVP are an important variable in characterizing its behavioral effects.
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Berro LF, Shields H, Odabas-Geldiay M, Rothbaum BO, Andersen ML, Howell LL. Acute effects of 3,4-methylenedioxymethamphetamine (MDMA) and R(-) MDMA on actigraphy-based daytime activity and sleep parameters in rhesus monkeys. Exp Clin Psychopharmacol 2018; 26:410-420. [PMID: 29939048 PMCID: PMC6072597 DOI: 10.1037/pha0000196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
3,4-Methylenedioxymethamphetamine (MDMA) affects monoaminergic pathways that play a critical role in sleep-wake cycles. Dopaminergic mechanisms are thought to mediate the sleep-disrupting effects of stimulant drugs. However, the mechanisms underlying the effects of MDMA on sleep-wake cycles and the effects of R(-) MDMA, a stereoisomer that lacks dopaminergic activity, on sleep remain unknown. The aim of the present study was to investigate the effects of racemic MDMA and R(-) MDMA on daytime activity and sleep-like parameters evaluated with actigraphy in adult rhesus macaques (Macaca mulatta, n = 6). Actiwatch monitors were attached to the monkeys' collars and actigraphy recording was conducted during baseline conditions and after the administration of acute intramuscular injections of saline (vehicle), racemic MDMA (0.3, 1.0, or 1.7 mg/kg), or R(-) MDMA (0.3, 1.0, or 1.7 mg/kg) at 9 or 16 h (3 h before "lights off"). Morning treatments had no effects on sleep-like parameters. Racemic MDMA decreased general daytime activity during the first hour after injection and increased daytime activity at 3 hr posttreatment. Although afternoon administration of racemic MDMA increased sleep latency, it improved other sleep parameters, decreasing wake time after sleep onset (WASO) and increasing sleep efficiency for subjects with low baseline sleep efficiency. Afternoon treatment with R(-) MDMA improved sleep measures, increasing sleep efficiency and decreasing sleep latency and WASO, while having no effects on daytime activity. The stimulant and sleep-disrupting effects of racemic MDMA are likely mediated by dopaminergic and noradrenergic mechanisms, while serotonergic pathways appear to be involved in the sleep-promoting effects of MDMA. (PsycINFO Database Record
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Affiliation(s)
- Laís F. Berro
- Yerkes National Primate Research Center, Emory University, 954 Gatewood Road N.E., Atlanta, GA, USA, 30329
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N State St, Jackson, MS, USA 39216
| | - Hannah Shields
- Yerkes National Primate Research Center, Emory University, 954 Gatewood Road N.E., Atlanta, GA, USA, 30329
| | - Melis Odabas-Geldiay
- Yerkes National Primate Research Center, Emory University, 954 Gatewood Road N.E., Atlanta, GA, USA, 30329
| | - Barbara O. Rothbaum
- Department of Psychiatry and Behavioral Science, Yerkes National Primate Research Center, Emory University, 954 Gatewood Road N.E., Atlanta, GA, USA, 30329
| | - Monica L. Andersen
- Yerkes National Primate Research Center, Emory University, 954 Gatewood Road N.E., Atlanta, GA, USA, 30329
- Department of Psychobiology, Universidade Federal de São Paulo, R. Napoleão de Barros, 925, 04021002 São Paulo, SP, Brazil
| | - Leonard L. Howell
- Yerkes National Primate Research Center, Emory University, 954 Gatewood Road N.E., Atlanta, GA, USA, 30329
- Department of Psychiatry and Behavioral Science, Yerkes National Primate Research Center, Emory University, 954 Gatewood Road N.E., Atlanta, GA, USA, 30329
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(±)-MDMA and its enantiomers: potential therapeutic advantages of R(-)-MDMA. Psychopharmacology (Berl) 2018; 235:377-392. [PMID: 29248945 DOI: 10.1007/s00213-017-4812-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 12/06/2017] [Indexed: 10/18/2022]
Abstract
The use of (±)-3,4-methylenedioxymethamphetamine ((±)-MDMA) as an adjunct to psychotherapy in the treatment of psychiatric and behavioral disorders dates back over 50 years. Only in recent years have controlled and peer-reviewed preclinical and clinical studies lent support to (±)-MDMA's hypothesized clinical utility. However, the clinical utility of (±)-MDMA is potentially mitigated by a range of demonstrated adverse effects. One potential solution could lie in the individual S(+) and R(-) enantiomers that comprise (±)-MDMA. Individual enantiomers of racemic compounds have been employed in psychiatry to improve a drug's therapeutic index. Although no research has explored the individual effects of either S(+)-MDMA or R(-)-MDMA in humans in a controlled manner, preclinical research has examined similarities and differences between the two molecules and the racemic compound. This review addresses information related to the pharmacodynamics, neurotoxicity, physiological effects, and behavioral effects of S(+)-MDMA and R(-)-MDMA that might guide preclinical and clinical research. The current preclinical evidence suggests that R(-)-MDMA may provide an improved therapeutic index, maintaining the therapeutic effects of (±)-MDMA with a reduced side effect profile, and that future investigations should investigate the therapeutic potential of R(-)-MDMA.
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Philogene-Khalid HL, Simmons SJ, Nayak S, Martorana RM, Su SH, Caro Y, Ranieri B, DiFurio K, Mo L, Gentile TA, Murad A, Reitz AB, Muschamp JW, Rawls SM. Stereoselective Differences between the Reinforcing and Motivational Effects of Cathinone-Derived 4-Methylmethcathinone (Mephedrone) In Self-Administering Rats. ACS Chem Neurosci 2017; 8:2648-2654. [PMID: 28885007 DOI: 10.1021/acschemneuro.7b00212] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Mephedrone (4-methylmethcathinone (4-MMC)) (MEPH) is a new psychoactive substance (NPS) of the synthetic cathinone class. MEPH has a chiral center and exists as two enantiomers (R-,S-MEPH), yet stereospecific effects of MEPH have not been extensively investigated in preclinical assays. Because significant behavioral and neurochemical differences can exist between enantiomers, probing effects of stereochemistry on biological activity enables separation of adverse and therapeutic effects. Our prior work showed that R-MEPH, relative to S-MEPH, produced greater locomotor activation, place preference, and facilitation of brain reward thresholds in rodents. The present study sought to determine if MEPH enantiomers display stereospecific reward and reinforcement in rat self-administration assays. In Experiment 1, rats were trained to self-administer racemic MEPH (0.50 mg/kg/inf), and dose substitution effects of R-MEPH (0.50 mg/kg/inf) and S-MEPH (0.25, 0.50, 2.00 mg/kg/inf) were examined. In Experiment 2, separate rats were trained to self-administer R-MEPH (0.25, 0.50, 2.00 mg/kg/inf) or S-MEPH (0.25, 0.50, 2.00 mg/kg/inf) and were thereafter evaluated under progressive-ratio access conditions. Within this cohort, 50 kHz ultrasonic vocalizations (USVs) were recorded to measure potential differences in subjective positive affect associated with MEPH enantiomer self-administration. We identified enantiomer- and dose-dependent effects on infusions earned during self-administration following acquisition of racemic MEPH, with greatest infusions under low-effort, fixed-ratio 1 access conditions from low-dose S-MEPH self-administration. When taxed with progressive-ratio access conditions, rats trained to self-administer R-MEPH showed higher break points than those of rats trained to self-administer S-MEPH. Additionally, R-MEPH elicited greatest rates of 50 kHz USVs compared to S-MEPH. Taken together, these data suggest that the R-enantiomer of MEPH is primarily responsible for the rewarding, reinforcing, and motivational properties of racemic MEPH, which increases our understanding of stereospecific preferences pertaining to MEPH abuse.
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Affiliation(s)
- Helene L. Philogene-Khalid
- Department of Pharmacology,
Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Steven J. Simmons
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Sunil Nayak
- Department of Pharmacology,
Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Rose M. Martorana
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Shu H. Su
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Yohanka Caro
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Brona Ranieri
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Kathryn DiFurio
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Lili Mo
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Taylor A. Gentile
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Ali Murad
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Allen B. Reitz
- Fox Chase Chemical Diversity Center Inc., Doylestown, Pennsylvania 18902, United States
| | - John W. Muschamp
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
| | - Scott M. Rawls
- Department of Pharmacology,
Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania 19140, United States
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12
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N-Alkylated Analogs of 4-Methylamphetamine (4-MA) Differentially Affect Monoamine Transporters and Abuse Liability. Neuropsychopharmacology 2017; 42:1950-1961. [PMID: 28530234 PMCID: PMC5561352 DOI: 10.1038/npp.2017.98] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 05/04/2017] [Accepted: 05/12/2017] [Indexed: 01/22/2023]
Abstract
Clandestine chemists synthesize novel stimulant drugs by exploiting structural templates known to target monoamine transporters for dopamine, norepinephrine, and serotonin (DAT, NET, and SERT, respectively). 4-Methylamphetamine (4-MA) is an emerging drug of abuse that interacts with transporters, but limited structure-activity data are available for its analogs. Here we employed uptake and release assays in rat brain synaptosomes, voltage-clamp current measurements in cells expressing transporters, and calcium flux assays in cells coexpressing transporters and calcium channels to study the effects of increasing N-alkyl chain length of 4-MA on interactions at DAT, NET, and SERT. In addition, we performed intracranial self-stimulation in rats to understand how the chemical modifications affect abuse liability. All 4-MA analogs inhibited uptake at DAT, NET, and SERT, but lengthening the amine substituent from methyl to ethyl, propyl, and butyl produced a stepwise decrease in potency. N-methyl 4-MA was an efficacious substrate-type releaser at DAT that evoked an inward depolarizing current and calcium influx, whereas other analogs did not exhibit these effects. N-methyl and N-ethyl 4-MA were substrates at NET, whereas N-propyl and N-butyl 4-MA were not. All analogs acted as SERT substrates, though N-butyl 4-MA had very weak effects. Intracranial self-stimulation in rats showed that elongating the N-alkyl chain decreased abuse-related effects in vivo that appeared to parallel reductions in DAT activity. Overall, converging lines of evidence show that lengthening the N-alkyl substituent of 4-MA reduces potency to inhibit transporters, eliminates substrate activity at DAT and NET, and decreases abuse liability of the compounds.
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13
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Huskinson SL, Naylor JE, Townsend EA, Rowlett JK, Blough BE, Freeman KB. Self-administration and behavioral economics of second-generation synthetic cathinones in male rats. Psychopharmacology (Berl) 2017; 234:589-598. [PMID: 27896377 PMCID: PMC5266647 DOI: 10.1007/s00213-016-4492-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 11/19/2016] [Indexed: 01/12/2023]
Abstract
RATIONALE Synthetic cathinones have become increasingly available as drugs of abuse. Distribution of these drugs is made possible by altering the chemical structures of prohibited cathinones and marketing them under misleading labels. Very little is known about the relative reinforcing effectiveness of new synthetic cathinones relative to known drugs of abuse. OBJECTIVE We examined self-administration of three second-generation synthetic cathinones: alpha-pyrrolidinopentiophenone (alpha-PVP), 4-methyl-N-ethylcathinone (4-MEC), and 4-methyl-alpha-pyrrolidinopropiophenone (4-MePPP) relative to methamphetamine. METHOD Male, Sprague-Dawley rats, implanted with intravenous catheters, were trained to self-administer methamphetamine (0.05 mg/kg/injection) under a fixed-ratio schedule. Following training, various doses of methamphetamine (0.006-0.1 mg/kg/injection), alpha-PVP (0.0015-0.1 mg/kg/injection), 4-MEC (0.1-3.2 mg/kg/injection), or 4-MePPP (0.1-0.8 mg/kg/injection) were available for self-administration in separate groups, followed by a behavioral-economics evaluation of the reinforcing effectiveness of each drug. RESULTS For all drugs, at least one dose functioned as a reinforcer. Alpha-PVP and 4-MePPP maintained the highest numbers of infusions per session and both were more effective reinforcers relative to methamphetamine. 4-MEC and methamphetamine were not significantly different in terms of infusions per session or reinforcing effectiveness. CONCLUSION Emerging synthetic cathinones whose primary pharmacological mechanism is to block dopamine uptake but with little effects on monoamine release or serotonin uptake may have a greater degree of abuse potential compared with known abused stimulants.
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Affiliation(s)
- S L Huskinson
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS, 39216, USA.
| | - J E Naylor
- Program in Neuroscience, University of Mississippi Medical Center, Jackson, MS, 39216, USA
| | - E A Townsend
- Program in Neuroscience, University of Mississippi Medical Center, Jackson, MS, 39216, USA
| | - J K Rowlett
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS, 39216, USA
- Program in Neuroscience, University of Mississippi Medical Center, Jackson, MS, 39216, USA
- Tulane National Primate Research Center, Tulane University School of Medicine, Covington, LA, 70433, USA
| | - B E Blough
- Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, NC, 27709, USA
| | - K B Freeman
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS, 39216, USA
- Program in Neuroscience, University of Mississippi Medical Center, Jackson, MS, 39216, USA
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14
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Negus SS, Banks ML. Decoding the Structure of Abuse Potential for New Psychoactive Substances: Structure-Activity Relationships for Abuse-Related Effects of 4-Substituted Methcathinone Analogs. Curr Top Behav Neurosci 2017; 32:119-131. [PMID: 27696217 PMCID: PMC5425248 DOI: 10.1007/7854_2016_18] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Many cathinone analogs act as substrates or inhibitors at dopamine, norepinephrine, and serotonin transporters (DAT, NET, SERT, respectively). Drug selectivity at DAT vs. SERT is a key determinant of abuse potential for monoamine transporter substrates and inhibitors, such that potency at DAT > SERT is associated with high abuse potential, whereas potency at DAT < SERT is associated with low abuse potential. Quantitative structure-activity relationship (QSAR) studies with a series of 4-substituted methcathinone analogs identified volume of the 4-position substituent on the methcathinone phenyl ring as one structural determinant of both DAT vs. SERT selectivity and abuse-related behavioral effects in an intracranial self-stimulation procedure in rats. Subsequent modeling studies implicated specific amino acids in DAT and SERT that might interact with 4-substituent volume to determine effects produced by this series of cathinone analogs. These studies illustrate use of QSAR analysis to investigate pharmacology of cathinones and function of monoamine transporters.
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Affiliation(s)
- S Stevens Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA.
| | - Matthew L Banks
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
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15
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Aronsen D, Bukholt N, Schenk S. Repeated administration of the 5-HT₁B/₁A agonist, RU 24969, facilitates the acquisition of MDMA self-administration: role of 5-HT₁A and 5-HT₁B receptor mechanisms. Psychopharmacology (Berl) 2016; 233:1339-47. [PMID: 26856853 DOI: 10.1007/s00213-016-4225-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 01/27/2016] [Indexed: 01/17/2023]
Abstract
RATIONALE 3,4 Methylenedioxymethamphetamine (MDMA) preferentially stimulates the release of serotonin (5-HT) that subsequently produces behavioral responses by activation of post-synaptic receptor mechanisms. The 5-HT1A and 5-HT1B receptors are both well localized to regulate dopamine (DA) release, and have been implicated in modulating the reinforcing effects of many drugs of abuse, but a role in acquisition of self-administration has not been determined. OBJECTIVES This study was designed to determine the effect of pharmacological manipulation of 5-HT1A and 5-HT1B receptor mechanisms on the acquisition of MDMA self-administration. METHODS The 5-HT1B/1A receptor agonist, RU 24969 (0.0 or 3.0 mg/kg, bid), was administered for 3 days in order to down-regulate both 5-HT1A and 5-HT1B receptors. Following the pretreatment phase, latency to acquisition of MDMA self-administration was measured. RESULTS Repeated administration of RU 24969 significantly decreased the latency to acquisition and increased the proportion of animals that acquired MDMA self-administration. Dose-effect curves for the 5-HT1A-mediated hyperactivity produced by the 5-HT1A agonist, 8-OH-DPAT, and the 5-HT1B-mediated adipsic response produced by RU 24969 were shifted rightward, suggesting a desensitization of 5-HT1A and 5-HT1B receptor mechanisms. CONCLUSIONS These data suggest that the initial reinforcing effects of MDMA are modulated by 5-HT1A and/or 5-HT1B receptor mechanisms. The potential impact of these changes on the DAergic response relevant to self-administration and a possible role in conditioned reinforcement pertaining to acquisition of self-administration are discussed.
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Affiliation(s)
- Dane Aronsen
- School of Psychology, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
| | - Natasha Bukholt
- School of Psychology, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
| | - Susan Schenk
- School of Psychology, Victoria University of Wellington, PO Box 600, Wellington, New Zealand.
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16
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John WS, Newman AH, Nader MA. Differential effects of the dopamine D3 receptor antagonist PG01037 on cocaine and methamphetamine self-administration in rhesus monkeys. Neuropharmacology 2015; 92:34-43. [PMID: 25576373 PMCID: PMC4346463 DOI: 10.1016/j.neuropharm.2014.12.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 12/17/2014] [Accepted: 12/22/2014] [Indexed: 12/17/2022]
Abstract
The dopamine D3 receptor (D3R) has been shown to mediate many of the behavioral effects of psychostimulants associated with high abuse potential. This study extended the assessment of the highly selective D3R antagonist PG01037 on cocaine and methamphetamine (MA) self-administration to include a food-drug choice procedure. Eight male rhesus monkeys (n=4/group) served as subjects in which complete cocaine and MA dose-response curves were determined daily in each session. When choice was stable, monkeys received acute and five-day treatment of PG01037 (1.0-5.6 mg/kg, i.v.). Acute administration of PG01037 was effective in reallocating choice from cocaine to food and decreasing cocaine intake, however, tolerance developed by day 5 of treatment. Up to doses that disrupted responding, MA choice and intake were not affected by PG01037 treatment. PG01037 decreased total reinforcers earned per session and the behavioral potency was significantly greater on MA-food choice compared to cocaine-food choice. Furthermore, the acute efficacy of PG01037 was correlated with the sensitivity of the D3/D2R agonist quinpirole to elicit yawning. These data suggest (1) that efficacy of D3R compounds in decreasing drug choice is greater in subjects with lower D3R, perhaps suggesting that it is percent occupancy that is the critical variable in determining efficacy and (2) differences in D3R activity in chronic cocaine vs. MA users. Although tolerance developed to the effects of PG01037 treatment on cocaine choice, tolerance did not develop to the disruptive effects on food-maintained responding. These findings suggest that combination treatments that decrease cocaine-induced elevations in DA may enhance the efficacy of D3R antagonists on cocaine self-administration.
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Affiliation(s)
- William S John
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, Baltimore, MD, USA.
| | - Michael A Nader
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
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17
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Gregg RA, Baumann MH, Partilla JS, Bonano JS, Vouga A, Tallarida CS, Velvadapu V, Smith GR, Peet MM, Reitz AB, Negus SS, Rawls SM. Stereochemistry of mephedrone neuropharmacology: enantiomer-specific behavioural and neurochemical effects in rats. Br J Pharmacol 2014; 172:883-94. [PMID: 25255824 DOI: 10.1111/bph.12951] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 09/11/2014] [Accepted: 09/20/2014] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND AND PURPOSE Synthetic cathinones, commonly referred to as 'bath salts', are a group of amphetamine-like drugs gaining popularity worldwide. 4-Methylmethcathinone (mephedrone, MEPH) is the most commonly abused synthetic cathinone in the UK, and exerts its effects by acting as a substrate-type releaser at monoamine transporters. Similar to other cathinone-related compounds, MEPH has a chiral centre and exists stably as two enantiomers: R-mephedrone (R-MEPH) and S-mephedrone (S-MEPH). EXPERIMENTAL APPROACH Here, we provide the first investigation into the neurochemical and behavioural effects of R-MEPH and S-MEPH. We analysed both enantiomers in rat brain synaptosome neurotransmitter release assays and also investigated their effects on locomotor activity (e.g. ambulatory activity and repetitive movements), behavioural sensitization and reward. KEY RESULTS Both enantiomers displayed similar potency as substrates (i.e. releasers) at dopamine transporters, but R-MEPH was much less potent than S-MEPH as a substrate at 5-HT transporters. Locomotor activity was evaluated in acute and repeated administration paradigms, with R-MEPH producing greater repetitive movements than S-MEPH across multiple doses. After repeated drug exposure, only R-MEPH produced sensitization of repetitive movements. R-MEPH produced a conditioned place preference whereas S-MEPH did not. Lastly, R-MEPH and S-MEPH produced biphasic profiles in an assay of intracranial self-stimulation (ICSS), but R-MEPH produced greater ICSS facilitation than S-MEPH. CONCLUSIONS AND IMPLICATIONS Our data are the first to demonstrate stereospecific effects of MEPH enantiomers and suggest that the predominant dopaminergic actions of R-MEPH (i.e. the lack of serotonergic actions) render this stereoisomer more stimulant-like when compared with S-MEPH. This hypothesis warrants further study.
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Affiliation(s)
- Ryan A Gregg
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA, USA; Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA, USA
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18
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Vouga A, Gregg RA, Haidery M, Ramnath A, Al-Hassani HK, Tallarida CS, Grizzanti D, Raffa RB, Smith GR, Reitz AB, Rawls SM. Stereochemistry and neuropharmacology of a 'bath salt' cathinone: S-enantiomer of mephedrone reduces cocaine-induced reward and withdrawal in invertebrates. Neuropharmacology 2014; 91:109-16. [PMID: 25496724 DOI: 10.1016/j.neuropharm.2014.11.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 11/15/2014] [Accepted: 11/17/2014] [Indexed: 01/21/2023]
Abstract
Knowledge about the neuropharmacology of mephedrone (MEPH) applies primarily to the racemate, or street form of the drug, but not to its individual enantiomers. Here, through chemical isolation of MEPH enantiomers and subsequent behavioral characterization in established invertebrate (planarian) assays, we began separating adverse effects of MEPH from potential therapeutic actions. We first compared stereotypical and environmental place conditioning (EPC) effects of racemic MEPH, S-MEPH, and R-MEPH. Stereotypy was enhanced by acute treatment (100-1000 μM) with each compound; however, S-MEPH was less potent and efficacious than racemate and R-MEPH. Both R-MEPH (10, 100, 250 μM) and racemate (100 μM) produced EPC, but S-MEPH was ineffective at all concentrations (10-100 μM). After showing that S-MEPH lacked rewarding efficacy, we investigated its ability to alter three of cocaine's behavioral effects (EPC, withdrawal, and stereotypy). Cocaine (1 μM) produced EPC that was abolished when S-MEPH (100 μM) was administered after cocaine conditioning. Spontaneous withdrawal from chronic cocaine exposure caused a reduction in motility that was not evident during acute or continuous cocaine treatment but was attenuated by S-MEPH (100 μM) treatment during the cocaine abstinence interval. Acute stereotypy produced by 1 mM cocaine, nicotine or racemic MEPH was not affected by S-MEPH (10-250 μM). The present results obtained using planarian assays suggest that the R-enantiomer of MEPH is predominantly responsible for its stimulant and rewarding effects and the S-enantiomer is capable of antagonizing cocaine's addictive-like behaviors without producing rewarding effects of its own.
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Affiliation(s)
- Alexandre Vouga
- Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA, USA; Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA, USA
| | - Ryan A Gregg
- Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA, USA; Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA, USA
| | - Maryah Haidery
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA, USA
| | - Anita Ramnath
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA, USA
| | - Hassan K Al-Hassani
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA, USA
| | - Christopher S Tallarida
- Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA, USA; Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA, USA
| | - David Grizzanti
- Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA, USA; Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA, USA
| | - Robert B Raffa
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA, USA
| | - Garry R Smith
- Fox Chase Chemical Diversity Center Inc., Doylestown, PA, USA
| | - Allen B Reitz
- Fox Chase Chemical Diversity Center Inc., Doylestown, PA, USA
| | - Scott M Rawls
- Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA, USA; Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA, USA.
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19
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Bradbury S, Bird J, Colussi-Mas J, Mueller M, Ricaurte G, Schenk S. Acquisition of MDMA self-administration: pharmacokinetic factors and MDMA-induced serotonin release. Addict Biol 2014; 19:874-84. [PMID: 23763615 DOI: 10.1111/adb.12069] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The current study aimed to elucidate the role of pharmacokinetic (PK) parameters and neurotransmitter efflux in explaining variability in (±) 3, 4-methylenedioxymethamphetamine (MDMA) self-administration in rats. PK profiles of MDMA and its major metabolites were determined after the administration of 1.0 mg/kg MDMA (iv) prior to, and following, the acquisition of MDMA self-administration. Synaptic levels of 5-hydroxytryptamine (5HT) and dopamine (DA) in the nucleus accumbens were measured following administration of MDMA (1.0 and 3.0 mg/kg, iv) using in vivo microdialysis and compared for rats that acquired or failed to acquire MDMA self-administration. Effects of the 5HT neurotoxin, 5,7 dihydroxytryptamine (5, 7-DHT), on the acquisition of MDMA and cocaine self-administration were also determined. In keeping with previous findings, approximately 50% of rats failed to meet a criterion for acquisition of MDMA self-administration. The PK profiles of MDMA and its metabolites did not differ between rats that acquired or failed to acquire MDMA self-administration. MDMA produced more overflow of 5HT than DA. The MDMA-induced 5HT overflow was lower in rats that acquired MDMA self-administration compared with those that did not acquire self-administration. In contrast, MDMA-induced DA overflow was comparable for the two groups. Prior 5,7-DHT lesions reduced tissue levels of 5HT and markedly increased the percentage of rats that acquired MDMA self-administration and also decreased the latency to acquisition of cocaine self-administration. These data suggest that 5HT limits the initial sensitivity to the positively reinforcing effects of MDMA and delays the acquisition of reliable self-administration.
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Affiliation(s)
- Sarah Bradbury
- School of Psychology; Victoria University of Wellington; New Zealand
| | - Judith Bird
- School of Psychology; Victoria University of Wellington; New Zealand
| | - Joyce Colussi-Mas
- School of Psychology; Victoria University of Wellington; New Zealand
| | - Melanie Mueller
- School of Medicine; Johns Hopkins University; Baltimore MD USA
| | - George Ricaurte
- School of Medicine; Johns Hopkins University; Baltimore MD USA
| | - Susan Schenk
- School of Psychology; Victoria University of Wellington; New Zealand
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Ball KT, Slane M. Tolerance to the locomotor-activating effects of 3,4-methylenedioxymethamphetamine (MDMA) predicts escalation of MDMA self-administration and cue-induced reinstatement of MDMA seeking in rats. Behav Brain Res 2014; 274:143-8. [PMID: 25127684 DOI: 10.1016/j.bbr.2014.08.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 07/04/2014] [Accepted: 08/04/2014] [Indexed: 02/03/2023]
Abstract
Pre-clinical studies of individual differences in addiction vulnerability have been increasing over recent years, but the amphetamine derivative 3,4-methylenedioxymethamphetamine (MDMA; ecstasy) has received relatively little attention in this regard. Previously, we reported large individual differences both in rats' initial behavioral response to experimenter-administered MDMA and their degree of behavioral sensitization to repeated administration. To determine whether these differences could predict subsequent patterns of MDMA-taking or -seeking behaviors we used the self-administration-extinction-reinstatement model to examine addiction-like behavior (i.e., escalation of MDMA self-administration and cue-induced reinstatement of MDMA seeking) in rats a priori characterized for either locomotor sensitization or tolerance to MDMA. Rats that developed tolerance to the locomotor-activating effects of MDMA had a significantly larger locomotor response to the first MDMA injection relative to rats that developed sensitization. Importantly, rats that developed tolerance subsequently displayed an escalation of MDMA self-administration over days, as well as clear cue-induced reinstatement of MDMA seeking following extinction. Conversely, rats that developed locomotor sensitization to MDMA subsequently maintained relatively stable levels of MDMA self-administration over days and showed no cue-induced reinstatement of MDMA seeking. These results show that differences in the level of psychomotor activation following acute and repeated MDMA administration can reliably predict two important addiction-like behaviors in rats, which may have implications in the prediction of compulsive MDMA use in humans.
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Affiliation(s)
- Kevin T Ball
- Department of Psychology, Bloomsburg University of Pennsylvania, 400 E. 2nd St., Bloomsburg, PA 17815, USA.
| | - Mylissa Slane
- Department of Psychology, Bloomsburg University of Pennsylvania, 400 E. 2nd St., Bloomsburg, PA 17815, USA
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21
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Abstract
Intracranial self-stimulation (ICSS) is a behavioral procedure in which operant responding is maintained by pulses of electrical brain stimulation. In research to study abuse-related drug effects, ICSS relies on electrode placements that target the medial forebrain bundle at the level of the lateral hypothalamus, and experimental sessions manipulate frequency or amplitude of stimulation to engender a wide range of baseline response rates or response probabilities. Under these conditions, drug-induced increases in low rates/probabilities of responding maintained by low frequencies/amplitudes of stimulation are interpreted as an abuse-related effect. Conversely, drug-induced decreases in high rates/probabilities of responding maintained by high frequencies/amplitudes of stimulation can be interpreted as an abuse-limiting effect. Overall abuse potential can be inferred from the relative expression of abuse-related and abuse-limiting effects. The sensitivity and selectivity of ICSS to detect abuse potential of many classes of abused drugs is similar to the sensitivity and selectivity of drug self-administration procedures. Moreover, similar to progressive-ratio drug self-administration procedures, ICSS data can be used to rank the relative abuse potential of different drugs. Strengths of ICSS in comparison with drug self-administration include 1) potential for simultaneous evaluation of both abuse-related and abuse-limiting effects, 2) flexibility for use with various routes of drug administration or drug vehicles, 3) utility for studies in drug-naive subjects as well as in subjects with controlled levels of prior drug exposure, and 4) utility for studies of drug time course. Taken together, these considerations suggest that ICSS can make significant contributions to the practice of abuse potential testing.
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Affiliation(s)
- S Stevens Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Laurence L Miller
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
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Ding Y, He N, Shoptaw S, Gao M, Detels R. Severity of club drug dependence and perceived need for treatment among a sample of adult club drug users in Shanghai, China. Soc Psychiatry Psychiatr Epidemiol 2014; 49:395-404. [PMID: 23715971 PMCID: PMC3797173 DOI: 10.1007/s00127-013-0713-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 05/15/2013] [Indexed: 11/28/2022]
Abstract
PURPOSE Examine the severity of club drug dependence and perceived need for treatment, and further identify their determinants among a sample of club drug users in Shanghai, China. METHODS Two hundred and seventy-six club drug users were recruited using respondent-driven sampling (RDS). Severity of dependence on club drugs was measured using the Severity of Dependence Scale (SDS). RESULTS 69.9% reported dependence on club drugs (i.e., SDS ≥ 4) and 36.6% reported severe dependence (i.e., SDS ≥ 6). One-eighth (12.7%) perceived need for drug treatment. Severe dependence on club drugs was more likely among those who reported recent use of ecstasy and those who had more depressive symptoms, but less likely among those reporting recent use of methamphetamine. Perceived need for treatment was more likely among those who lived with a spouse or boy/girlfriend, but less likely among those had prior drug treatment experience and more severe club drug dependence. CONCLUSIONS Our findings suggest that educational activities should be implemented to raise public awareness about the powerful addictive properties of club drugs, along with efforts to reduce stigma towards drug abuse and psychiatric disorders. Programs to motivate drug users to seek treatment and encourage treatment linkage are urgently needed.
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Affiliation(s)
- Yingying Ding
- Department of Epidemiology, School of Public Health, Fudan University and The Key Laboratory of Public Health Safety of Ministry of Education, Shanghai, China,Department of Epidemiology, Jonathan and Karin Fielding School of Public Health, University of California, Los Angeles, Los Angeles, CA, USA
| | - Na He
- Department of Epidemiology, School of Public Health, Fudan University and The Key Laboratory of Public Health Safety of Ministry of Education, Shanghai, China
| | - Steven Shoptaw
- Department of Family Medicine and Psychiatry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Meiyang Gao
- Department of Epidemiology, School of Public Health, Fudan University and The Key Laboratory of Public Health Safety of Ministry of Education, Shanghai, China
| | - Roger Detels
- Department of Epidemiology, Jonathan and Karin Fielding School of Public Health, University of California, Los Angeles, Los Angeles, CA, USA,Correspondence to Roger Detels, Department of Epidemiology, UCLA Fielding School of Public Health, Los Angeles, CA, 90095-1772, USA;
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Bauer CT, Banks ML, Blough BE, Negus SS. Rate-dependent effects of monoamine releasers on intracranial self-stimulation in rats: implications for abuse liability assessment. Behav Pharmacol 2013; 24:448-58. [PMID: 23851484 PMCID: PMC4028167 DOI: 10.1097/fbp.0b013e328363d1a4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
'Rate dependency' in the discipline of behavioral pharmacology describes a phenomenon wherein the effect of a drug on the rate of a behavior varies systematically as a function of the baseline, predrug rate of that behavior. Historically, rate-dependency studies have compared drug effects on different baseline rates of behavior maintained either by different schedules of reinforcement or during sequential segments of a fixed-interval schedule. The current experiment generated different baseline rates of behavior by altering frequency of electrical stimulation in an intracranial self-stimulation assay. Amphetamine and 10 other monoamine releasers were analyzed for their ability to produce rate-dependent effects in this assay. There were three main findings. First, all compounds produced rate-dependent effects at some dose. Second, one parameter of rate-dependency plots (peak Y-intercept of the regression line) correlated with in-vitro neurochemical data on selectivity of these compounds to release dopamine versus serotonin (P<0.025, R=0.50). Lastly, a correlation between peak Y-intercept and breakpoints under a progressive-ratio procedure in nonhuman primates was also significant (P<0.05, R=0.64). Overall, these results extend the rate-dependent effects of monoamine releasers to behavior maintained under intracranial self-stimulation and suggest that, at least for monoamine releasers, the Y-intercept parameter of rate-dependency plots might be a useful metric of drug reward and predictor of drug self-administration measures of drug reinforcement.
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Affiliation(s)
- Clayton T Bauer
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
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Substituted cathinone products: a new trend in "bath salts" and other designer stimulant drug use. J Addict Med 2013; 7:153-62. [PMID: 23732954 DOI: 10.1097/adm.0b013e31829084b7] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
There is a growing concern about the availability of a new generation of "designer drug" stimulants that are marketed as "bath salts" and other household products. The products are not true bath salts and contain substituted cathinone stimulant substances, such as methylenedioxypyrovalerone (MDPV) and mephedrone. Calls to the American Association of Poison Control Centers regarding "bath salts" consumption began in 2010 and have continued since that time. Few reports of systematic epidemiologic surveillance or definitive clinical effects of toxicity specifically associated with "bath salts" consumption have been reported in the medical literature. The current narrative review describes the growing trend of designer substituted cathinone use, pharmacology, clinical effects, and recent regulatory changes. It is hoped that a greater understanding of the clinical effects and use patterns will help inform policy and practice.
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Bauer CT, Banks ML, Blough BE, Negus SS. Use of intracranial self-stimulation to evaluate abuse-related and abuse-limiting effects of monoamine releasers in rats. Br J Pharmacol 2013; 168:850-62. [PMID: 22978626 DOI: 10.1111/j.1476-5381.2012.02214.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 08/17/2012] [Accepted: 08/30/2012] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Monoamine releasers constitute a class of drugs that promote the release of dopamine (DA), serotonin (5-HT) and/or norepinephrine. Although some drugs in this class are well-known drugs of abuse (amphetamine, methamphetamine), others are thought to have reduced (3,4-methylenedioxy-N-methylamphetamine [MDMA]) or no (fenfluramine) abuse potential. The purpose of this study was to further elucidate the role of dopamine versus serotonin selectivity on expression of abuse-related effects produced by monoamine releasers in an assay of intracranial self-stimulation (ICSS) in rats. EXPERIMENTAL APPROACH This study evaluated effects produced in a frequency-rate ICSS procedure by 11 monoamine releasers that vary in selectivity to release DA versus 5-HT. KEY RESULTS Efficacy of monoamine releasers to facilitate ICSS correlated with DA-selectivity, such that DA-selective releasers exclusively facilitated ICSS, a 5-HT-selective releaser exclusively depressed ICSS, and mixed-action releasers both facilitated low ICSS rates and depressed high ICSS rates. Fixed-proportion mixtures of a DA-selective releaser and a 5-HT-selective releaser recapitulated effects of mixed-action releasers. Efficacy of monoamine releasers to facilitate ICSS also correlated with previously published data on efficacy to maintain self-administration in rhesus monkeys responding under a progressive-ratio schedule of reinforcement. CONCLUSIONS AND IMPLICATIONS These data support the importance of selectivity for DA versus 5-HT in determining abuse potential of monoamine releasers and demonstrate a novel correlation between rat ICSS and nonhuman primate self-administration measures of abuse-related effects. Taken together, these results support the use of ICSS in rats as an experimental tool to study the expression and pharmacological determinants of abuse-related effects of monoamine releasers.
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Affiliation(s)
- C T Bauer
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
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26
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Andersen ML, Diaz MP, Murnane KS, Howell LL. Effects of methamphetamine self-administration on actigraphy-based sleep parameters in rhesus monkeys. Psychopharmacology (Berl) 2013; 227:101-7. [PMID: 23263461 PMCID: PMC3622170 DOI: 10.1007/s00213-012-2943-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 11/30/2012] [Indexed: 10/27/2022]
Abstract
RATIONALE Sleep disorders and substance abuse are highly comorbid. Although methamphetamine is a very commonly abused drug, to the best of our knowledge, no study has evaluated its effects on sleep during drug use and abstinence under well-controlled conditions in laboratory animals. OBJECTIVES The objective of this study was to examine the effects of methamphetamine self-administration on sleep-like measures in nonhuman primates. METHODS Adult male rhesus monkeys (Macaca mulatta; n = 4) self-administered methamphetamine (0.01 and 0.03 mg/kg/injection, i.v.) under a fixed-ratio 20 schedule of reinforcement (60-min sessions once a day, 5 days per week) for 5 weeks. Sleep-like measures were evaluated with Actiwatch monitors before, during, and after each period of drug self-administration. RESULTS Both doses of methamphetamine reliably maintained self-administration. Methamphetamine (0.03 mg/kg) increased derived measures of latency to sleep onset and sleep fragmentation, and decreased sleep efficiency compared to abstinence, and higher methamphetamine intake predicted worse sleep quality. However, sleep normalized immediately after the discontinuation of methamphetamine self-administration. CONCLUSIONS Methamphetamine markedly disrupted sleep-like measures; however, methamphetamine self-administration did not disrupt sleep quality during subsequent periods of drug abstinence.
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Affiliation(s)
- Monica L. Andersen
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA,Departamento de Psicobiologia, Universidade Federal de São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Maylen P. Diaz
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA
| | - Kevin S. Murnane
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA
| | - Leonard L. Howell
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA,Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, GA, USA,Corresponding Author: Leonard L. Howell, PhD, Yerkes National Primate Research Center, Emory University, 954 Gatewood Rd, Atlanta, GA 30329, P: 404-727-7786, F: 404-727-1266,
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Kirkpatrick MG, Gunderson EW, Perez AY, Haney M, Foltin RW, Hart CL. A direct comparison of the behavioral and physiological effects of methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) in humans. Psychopharmacology (Berl) 2012; 219:109-22. [PMID: 21713605 PMCID: PMC4430833 DOI: 10.1007/s00213-011-2383-4] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Accepted: 06/10/2011] [Indexed: 11/28/2022]
Abstract
RATIONALE Despite their chemical similarities, methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) produce differing neurochemical and behavioral responses in animals. In humans, individual studies of methamphetamine and MDMA indicate that the drugs engender overlapping and divergent effects; there are only limited data comparing the two drugs in the same individuals. OBJECTIVES This study examined the effects of methamphetamine and MDMA using a within-subject design. METHODS Eleven adult volunteers completed this 13-day residential laboratory study, which consisted of four 3-day blocks of sessions. On the first day of each block, participants received oral methamphetamine (20, 40 mg), MDMA (100 mg), or placebo. Drug plasma concentrations, cardiovascular, subjective, and cognitive/psychomotor performance effects were assessed before drug administration and after. Food intake and sleep were also assessed. On subsequent days of each block, placebo was administered and residual effects were assessed. RESULTS Acutely, both drugs increased cardiovascular measures and "positive" subjective effects and decreased food intake. In addition, when asked to identify each drug, participants had difficulty distinguishing between the amphetamines. The drugs also produced divergent effects: methamphetamine improved performance and disrupted sleep, while MDMA increased "negative" subjective-effect ratings. Few residual drug effects were noted for either drug. CONCLUSIONS It is possible that the differences observed could explain the differential public perception and abuse potential associated with these amphetamines. Alternatively, the route of administration by which the drugs are used recreationally might account for the many of the effects attributed to these drugs (i.e., MDMA is primarily used orally, whereas methamphetamine is used by routes associated with higher abuse potential).
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Affiliation(s)
- Matthew G. Kirkpatrick
- Department of Psychology, Columbia University, New York, NY, USA; Division on Substance Abuse, New York State Psychiatric Institute and Department of Psychiatry, College of Physicians and Surgeons of Columbia University, New York, NY, USA; Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, IL, USA
| | - Erik W. Gunderson
- Division on Substance Abuse, New York State Psychiatric Institute and Department of Psychiatry, College of Physicians and Surgeons of Columbia University, New York, NY, USA
| | - Audrey Y. Perez
- Division on Substance Abuse, New York State Psychiatric Institute and Department of Psychiatry, College of Physicians and Surgeons of Columbia University, New York, NY, USA
| | - Margaret Haney
- Division on Substance Abuse, New York State Psychiatric Institute and Department of Psychiatry, College of Physicians and Surgeons of Columbia University, New York, NY, USA
| | - Richard W. Foltin
- Division on Substance Abuse, New York State Psychiatric Institute and Department of Psychiatry, College of Physicians and Surgeons of Columbia University, New York, NY, USA
| | - Carl L. Hart
- Department of Psychology, Columbia University, New York, NY, USA; Division on Substance Abuse, New York State Psychiatric Institute and Department of Psychiatry, College of Physicians and Surgeons of Columbia University, New York, NY, USA; New York State Psychiatric Institute, 1051 Riverside Dr., Unit 120, New York, NY 10032, USA
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Schenk S, Colussi-Mas J, Do J, Bird J. Profile of MDMA Self-Administration from a Large Cohort of Rats: MDMA Develops a Profile of Dependence with Extended Testing. ACTA ACUST UNITED AC 2012. [DOI: 10.4303/jdar/235602] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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29
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Mohamed WM, Hamida SB, Cassel JC, de Vasconcelos AP, Jones BC. MDMA: Interactions with other psychoactive drugs. Pharmacol Biochem Behav 2011; 99:759-74. [DOI: 10.1016/j.pbb.2011.06.032] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 05/10/2011] [Accepted: 06/28/2011] [Indexed: 10/18/2022]
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30
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Moreno AY, Mayorov AV, Janda KD. Impact of distinct chemical structures for the development of a methamphetamine vaccine. J Am Chem Soc 2011; 133:6587-95. [PMID: 21473576 DOI: 10.1021/ja108807j] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
(+)-Methamphetamine (METH) use and addiction has grown at alarming rates over the past two decades, while no approved pharmacotherapy exists for its treatment. Immunopharmacotherapy has the potential to offer relief through producing highly specific antibodies that prevent drug penetration across the blood-brain barrier thus decreasing reinforcement of the behavior. Current immunotherapy efforts against methamphetamine have focused on a single hapten structure, namely linker attachment at the aromatic ring of the METH molecule. Hapten design is largely responsible for immune recognition, as it affects presentation of the target antigen and thus the quality of the response. In the current paper we report the systematic generation of a series of haptens designed to target the most stable conformations of methamphetamine as determined by molecular modeling. On the basis of our previous studies with nicotine, we show that introduction of strategic molecular constraint is able to maximize immune recognition of the target structure as evidenced by higher antibody affinity. Vaccination of GIX(+) mice with six unique METH immunoconjugates resulted in high antibody titers for three particularly promising formulations (45-108 μg/mL, after the second immunization) and high affinity (82, 130, and 169 nM for MH2, MH6, and MH7 hapten-based vaccines, respectively). These findings represent a unique approach to the design of new vaccines against methamphetamine abuse.
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Affiliation(s)
- Amira Y Moreno
- Department of Chemistry, Skaggs Institute for Chemical Biology, 10550 N. Torrey Pines Road, La Jolla, California 92037, USA
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31
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O’Connor EC, Chapman K, Butler P, Mead AN. The predictive validity of the rat self-administration model for abuse liability. Neurosci Biobehav Rev 2011; 35:912-38. [DOI: 10.1016/j.neubiorev.2010.10.012] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 10/21/2010] [Accepted: 10/23/2010] [Indexed: 11/15/2022]
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32
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Schenk S. MDMA ("ecstasy") abuse as an example of dopamine neuroplasticity. Neurosci Biobehav Rev 2010; 35:1203-18. [PMID: 21184779 DOI: 10.1016/j.neubiorev.2010.12.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 12/12/2010] [Accepted: 12/15/2010] [Indexed: 01/12/2023]
Abstract
A number of reviews have focused on the short- and long-term effects of MDMA and, in particular, on the persistent deficits in serotonin neurotransmission that accompany some exposure regimens. The mechanisms underlying the serotonin deficits and their relevance to various behavioral and cognitive consequences of MDMA use are still being debated. It has become clear, however, that some individuals develop compulsive and uncontrolled drug-taking that is consistent with abuse. For other drugs of abuse, this transition has been attributed to neuroadaptations in central dopamine mechanisms that occur as a function of repeated drug exposure. A question remains as to whether similar neuroadaptations occur as a function of exposure to MDMA and the impact of serotonin neurotoxicity in the transition from use to abuse. This review focuses specifically on this issue by first providing an overview of human studies and then reviewing the animal literature with specific emphasis on paradigms that measure subjective effects of drugs and self-administration as indices of abuse liability. It is suggested that serotonin deficits resulting from repeated exposure to MDMA self-administration lead to a sensitized dopaminergic response to the drug and that this sensitized response renders MDMA comparable to other drugs of abuse.
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Affiliation(s)
- Susan Schenk
- Victoria University of Wellington, School of Psychology, Kelburn Pde, Easterfield Bldg Rm 702, Wellington, New Zealand.
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Drug seeking in response to a priming injection of MDMA in rats: relationship to initial sensitivity to self-administered MDMA and dorsal striatal dopamine. Int J Neuropsychopharmacol 2010; 13:1315-27. [PMID: 20334725 DOI: 10.1017/s1461145710000283] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
In laboratory animals, exposure to priming injections of 3,4-methylenedioxymethamphetamine (MDMA) produced drug seeking following extinction of MDMA self-administration. This study aimed to evaluate whether the magnitude of drug seeking was related to latency to acquisition of MDMA self-administration and increases in striatal dopamine, as measured by in-vivo microdialysis. Rats were given daily access to MDMA self-administration until they earned a total of 240 infusions (total intake of 165 mg/kg MDMA). Twelve of the 20 rats acquired self-administration within the temporal limits of the study and the latency to meet the criterion ranged from 9 d to 37 d. An experimenter-administered injection of MDMA (10.0 mg/kg i.p.) produced drug seeking in these rats, and the number of responses was significantly higher than responses produced by rats that failed to meet the criterion or by yoked control rats that received the drug passively. For rats that met the criterion, drug seeking was negatively correlated with the number of days to self-administer the criterion number of MDMA infusions and positively correlated with MDMA-produced dopamine in the dorsal striatum. Importantly, MDMA-produced dopamine overflow was greater for the rats that met the criterion. These findings suggest that drug seeking is influenced by initial sensitivity to the reinforcing effects of MDMA and to drug-produced increases in striatal dopamine.
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Murnane KS, Fantegrossi WE, Godfrey JR, Banks ML, Howell LL. Endocrine and neurochemical effects of 3,4-methylenedioxymethamphetamine and its stereoisomers in rhesus monkeys. J Pharmacol Exp Ther 2010; 334:642-50. [PMID: 20466795 DOI: 10.1124/jpet.110.166595] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
3,4-Methylenedioxymethamphetamine (MDMA) is an amphetamine derivative that elicits complex biological effects in humans. One plausible mechanism for this phenomenon is that racemic MDMA is composed of two stereoisomers that exhibit qualitatively different pharmacological effects. In support of this, studies have shown that R(-)-MDMA tends to have hallucinogen-like effects, whereas S(+)-MDMA tends to have psychomotor stimulant-like effects. However, relatively little is known about whether these stereoisomers engender different endocrine and neurochemical effects. In the present study, the endocrine and neurochemical effects of each stereoisomer and the racemate were assessed in four rhesus monkeys after intravenous delivery at doses (1-3 mg/kg) that approximated voluntary self-administration by rhesus monkeys and human recreational users. Specifically, fluorescence-based enzyme-linked immunosorbent assay was used to assess plasma prolactin concentrations, and in vivo microdialysis was used to assess extracellular dopamine and serotonin concentrations in the dorsal striatum. R(-)-MDMA, but not S(+)-MDMA, significantly increased plasma prolactin levels and the effects of S,R(+/-)-MDMA were intermediate to each of its component stereoisomers. Although S(+)-MDMA did not alter prolactin levels, it did significantly increase extracellular serotonin concentrations. In addition, S(+)-MDMA, but not R(-)-MDMA, significantly increased dopamine concentrations. Furthermore, as in the prolactin experiment, the effects of the racemate were intermediate to each of the stereoisomers. These studies demonstrate the stereoisomers of MDMA engender qualitatively different endocrine and neurochemical effects, strengthening the inference that differences in these stereoisomers might be the mechanism producing the complex biological effects of the racemic mixture of MDMA in humans.
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Affiliation(s)
- K S Murnane
- Division of Neuroscience, Yerkes National Primate Research Center, Atlanta, Georgia 30322, USA
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Degenhardt L, Bruno R, Topp L. Is ecstasy a drug of dependence? Drug Alcohol Depend 2010; 107:1-10. [PMID: 19836170 DOI: 10.1016/j.drugalcdep.2009.09.009] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 09/16/2009] [Accepted: 09/18/2009] [Indexed: 11/16/2022]
Abstract
This paper examines the evidence for an MDMA or "ecstasy" dependence syndrome. Animal evidence suggests that MDMA may be a less potent reinforcer than other drugs, but that it does have dependence potential. This suggests that (a) ecstasy dependence might be less likely than dependence upon other drugs; and (b) factors related to the behavioural and psychological aspects of reward and dependence may make a relatively greater contribution for ecstasy than for other drugs, where physically centred (and better understood) features of dependence may be more salient. Human evidence supports this proposition. Some people report problems with their use, but the literature suggests that physical features play a more limited role than psychological ones. Tolerance is apparent, and withdrawal is self-reported, but it is unclear whether these reports distinguish sub-acute effects of ecstasy intoxication from symptoms reflective of neuroadaptive processes underlying a "true" withdrawal syndrome. Studies examining the structure of dependence upon ecstasy suggest it may be different from drugs such as alcohol, methamphetamine and opioids. Consistent with studies of hallucinogens, a two-factor structure has been identified with factors suggestive of "compulsive use" and "escalating use". Regardless of the nature of any dependence syndrome, however, there is evidence to suggest that a minority of ecstasy users become concerned about their use and seek treatment. Further controlled studies are required to investigate this phenomenon.
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Affiliation(s)
- Louisa Degenhardt
- National Drug and Alcohol Research Centre, University of New South Wales, Sydney, NSW 2052, Australia.
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36
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Self-administration of (+)-methamphetamine and (+)-pseudoephedrine, alone and combined, by rhesus monkeys. Pharmacol Biochem Behav 2010; 95:198-202. [PMID: 20100506 DOI: 10.1016/j.pbb.2010.01.005] [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: 10/15/2009] [Revised: 12/29/2009] [Accepted: 01/18/2010] [Indexed: 11/23/2022]
Abstract
(+)-Methamphetamine (MA) is an illicit psychostimulant that can be synthesized from the nonprescription nasal decongestant, (+)-pseudoephedrine (PE). While MA is widely abused, PE appears to have little or no abuse liability in currently available formulations. However, PE produces centrally-mediated dopaminergic effects that are linked to the reinforcing effects of MA and other illicit psychostimulants and has been reported to function as a positive reinforcer in non-human primates. There has yet to be an assessment of the relative reinforcing effects of MA and PE. Therefore, the current study compared the reinforcing potency and strength of MA and PE, alone and combined, in four rhesus monkeys that were allowed to self-administer MA (0.003-0.3 mg/kg/inj), PE (0.1-3.0 mg/kg/inj), or combinations of the two under a progressive-ratio schedule of reinforcement. (+)-Methamphetamine functioned as a positive reinforcer in a dose-dependent manner. (+)-Pseudoephedrine also functioned as a positive reinforcer, but was less potent than MA. There were no differences in maximum injections between MA, PE, or any of the combinations of the two. Dose-addition analysis and the interaction index indicated that combinations of PE and MA were either additive or sub-additive in their reinforcing effects. These results suggest that, while MA is a more potent reinforcer than PE, the two drugs are comparable in terms of reinforcing strength. However, MA and PE do not appear to interact in a manner that enhances their relative reinforcing effects.
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Brennan KA, Colussi-Mas J, Carati C, Lea RA, Fitzmaurice PS, Schenk S. Methamphetamine self-administration and the effect of contingency on monoamine and metabolite tissue levels in the rat. Brain Res 2009; 1317:137-46. [PMID: 19962371 DOI: 10.1016/j.brainres.2009.11.069] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 11/24/2009] [Accepted: 11/24/2009] [Indexed: 11/25/2022]
Abstract
A number of studies have shown that exposure to high doses of methamphetamine (MA) is toxic to central dopamine (DA) and serotonin (5-HT) neurons. In most of those studies, however, high doses of MA were experimenter-administered during a short exposure time. Because contingency is a determinant for many effects of drug exposure, the present objective was to investigate the effects of self-administered MA on tissue monoamine levels following a short (24 hours) or longer (7 days) withdrawal period. As previously reported, a noncontingent "binge" high-dose treatment regimen (4 injections of 10 mg/kg MA administered every 2 hours) produced persistent depletion of cortical 5-HT and striatal DA. Effects of self-administered MA (0.1 mg/kg/infusion) were then determined following a 20-day duration where a yoked design was employed such that some rats received MA contingent on an operant lever press and others received either MA or saline dependent on the responses of the contingent rat. Self-administered MA produced a transient striatal DA depletion with a more persistent increase in DA turnover, indicating the presence of some lasting adaptations. Furthermore, the yoked design revealed that there was no effect of contingency on these parameters.
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Affiliation(s)
- Katharine A Brennan
- Institute of Environmental Science and Research Ltd, P.O. Box 50-348, Porirua 5240, New Zealand.
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Reveron ME, Maier EY, Duvauchelle CL. Behavioral, thermal and neurochemical effects of acute and chronic 3,4-methylenedioxymethamphetamine ("Ecstasy") self-administration. Behav Brain Res 2009; 207:500-7. [PMID: 19891989 DOI: 10.1016/j.bbr.2009.10.038] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 10/23/2009] [Accepted: 10/30/2009] [Indexed: 11/29/2022]
Abstract
3,4-Methylenedioxymethamphetamine (MDMA) is a popular methamphetamine derivative associated with young adults and all-night dance parties. However, the enduring effects of MDMA at voluntary intake levels have not been extensively investigated. In this study, MDMA-influenced behaviors and core temperatures were assessed over the course of 20 daily MDMA self-administration sessions in rats. In vivo microdialysis techniques were used in a subsequent MDMA challenge test session to determine extracellular nucleus accumbens dopamine (NAcc DA) and serotonin (5-HT) levels in MDMA-experienced and naïve animals before and after a self-administered MDMA injection (3.0mg/kg, i.v.). During self-administration sessions, gradual and significant increases in MDMA intake and MDMA-stimulated locomotor activity were observed across sessions. Core temperature significantly decreased during initial MDMA sessions, but was unaltered by the last 10 sessions. In the MDMA challenge test, MDMA-naïve rats showed significantly higher NAcc 5-HT responses compared to MDMA-experienced rats, though MDMA experience did not affect the magnitude of NAcc DA response. The overall findings suggest that changes in MDMA-induced responses over the course of increasing levels of drug exposure may reflect the development of tolerance to a number of MDMA effects.
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Affiliation(s)
- Maria Elena Reveron
- College of Pharmacy, Division of Pharmacology and Toxicology, University of Texas, Austin, TX 78712-0125, USA
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Role of dopamine transporters in the behavioral effects of 3,4-methylenedioxymethamphetamine (MDMA) in nonhuman primates. Psychopharmacology (Berl) 2009; 205:337-47. [PMID: 19421742 PMCID: PMC3230037 DOI: 10.1007/s00213-009-1545-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Accepted: 04/11/2009] [Indexed: 10/20/2022]
Abstract
RATIONALE The interoceptive and reinforcing effects of 3,4-methylenedioxymethamphetamine (MDMA) are similar to those of psychostimulants, but the role of dopamine in the behavioral effects of MDMA is not well documented, especially in primates. OBJECTIVE The aim of this study was to assess the role of dopamine in the behavioral effects of MDMA in two nonhuman primate species. METHODS The behavioral effects of MDMA, with and without serotonergic or dopaminergic pretreatments, were studied in squirrel monkeys trained to respond under a fixed-interval schedule of stimulus termination; effects on caudate dopamine levels were studied in a separate group of squirrel monkeys using in vivo microdialysis. Positron emission tomography neuroimaging with the dopamine transporter (DAT) ligand [18F]FECNT was used to determine DAT occupancy by MDMA in rhesus monkeys. RESULTS MDMA (0.5-1.5 mg/kg) did not induce behavioral stimulant effects, but the highest dose of MDMA suppressed responding. Pretreatment with fluoxetine (3.0 mg/kg) or the selective 5HT(2A) antagonist M100907 (0.03-0.3 mg/kg) attenuated the rate suppressing effects of MDMA. In contrast, pretreatment with the selective dopamine transporter inhibitor RTI-177 (0.1 mg/kg) did not alter the rate suppressing effects of MDMA. Administration of MDMA at a dose that suppressed operant behavior had negligible effects on extracellular dopamine. The percent DAT occupancy of MDMA at a dose that suppressed operant behavior also was marginal and reflected low in vivo potency for DAT binding. CONCLUSIONS Collectively, these results indicate that behaviorally relevant doses of MDMA do not induce behavioral stimulant or dopamine transporter-mediated effects in nonhuman primates.
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Wang Z, Woolverton WL. Super-additive interaction of the reinforcing effects of cocaine and H1-antihistamines in rhesus monkeys. Pharmacol Biochem Behav 2008; 91:590-5. [PMID: 18930758 DOI: 10.1016/j.pbb.2008.09.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 09/25/2008] [Accepted: 09/26/2008] [Indexed: 11/25/2022]
Abstract
Histamine H1 receptor antagonists can be sedating and have behavioral effects, including reinforcing and discriminative stimulus effects in non-humans, that predict abuse liability. Previous research has suggested that antihistamines can enhance the effects of some drugs of abuse. We have reported a synergistic interaction between cocaine and diphenhydramine (DPH) in a self-administration assay with monkeys. The present study was designed to extend those findings to other combinations of cocaine and DPH, and to the mixture of cocaine and another H1-antihistamine, pyrilamine. Rhesus monkeys were prepared with chronic i.v. catheters and allowed to self-administer cocaine, DPH or pyrilamine alone or as mixtures under a progressive-ratio schedule of reinforcement. Cocaine, DPH and pyrilamine alone maintained self-administration and cocaine was the stronger reinforcer. When cocaine was combined with DPH or pyrilamine in a 1:1, 1:2 or 2:1 ratio of the ED(50)s, the combinations were super-additive as reinforcers. Reinforcing strength of the combinations was greater than that of the antihistamines alone but not greater than cocaine. The data support the prediction that the combination of cocaine and histamine H1 receptor antagonists could have enhanced potential for abuse relative to either drug alone. The interaction may involve dopamine systems in the CNS.
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Affiliation(s)
- Zhixia Wang
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS 39216, USA
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Self-administration of drug mixtures by monkeys: combining drugs with comparable mechanisms of action. Psychopharmacology (Berl) 2008; 196:575-82. [PMID: 18026937 PMCID: PMC3109501 DOI: 10.1007/s00213-007-0991-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Accepted: 10/16/2007] [Indexed: 10/22/2022]
Abstract
RATIONALE Abuse of drug mixtures is common. Drug interactions that are super-additive in terms of reinforcing effects may contribute to this phenomenon. Although quantitative methods for assessing drug interactions have been developed, they have not been widely applied to the analysis of reinforcing effects. OBJECTIVES The present experiment was designed to study self-administration of mixtures of drugs with comparable pharmacological mechanisms of action. Our hypothesis was that the drugs would be dose-additive. MATERIALS AND METHODS Rhesus monkeys prepared with i.v. catheters were allowed to self-administer cocaine or saline under a progressive-ratio schedule in baseline sessions. When responding was stable, two mu opioid agonists, alfentanil and remifentanil, were tested alone in one group (n = 5). Two dopamine (DA) uptake blockers, cocaine and RTI-117 were tested in the other group (n = 6). Next, mixtures of doses of the two opioids or the two DA uptake blockers were tested in approximate 1:1, 1:2, and 2:1 ratios of their ED50s. Results were analyzed using isobolographic techniques. RESULTS All drugs alone and drug mixtures functioned as positive reinforcers in a dose-related manner. There was no difference between experimentally determined ED50 values and predicted additive ED50 values for any mixture. Maximum responding maintained by mixtures, a measure of reinforcing strength, did not differ from that for single drugs. CONCLUSIONS Mixtures of various proportions of two drugs with comparable mechanisms of action were additive, i.e., they did not interact. This result will serve as the basis for comparison to studies of mixtures of drugs with various mechanisms of action.
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Banks ML, Sprague JE, Czoty PW, Nader MA. Effects of ambient temperature on the relative reinforcing strength of MDMA using a choice procedure in monkeys. Psychopharmacology (Berl) 2008; 196:63-70. [PMID: 17899019 PMCID: PMC2268611 DOI: 10.1007/s00213-007-0932-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Accepted: 08/28/2007] [Indexed: 12/30/2022]
Abstract
RATIONALE 3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is frequently used in hot environments, such as rave parties. Studies in laboratory animals have shown that ambient temperature can alter the behavioral and neurochemical effects of MDMA. OBJECTIVE To examine the influence of ambient temperature on the relative reinforcing strength of MDMA and reinstatement of behavior previously maintained by MDMA is the objective of the study. METHODS The effects of cool (18 degrees C), room (24 degrees C), and warm (31 degrees C) temperatures were examined when MDMA was available under a concurrent fixed-ratio 30 schedule of MDMA (saline, 0.03-0.3 mg/kg/injection) and food choice in rhesus monkeys (n = 5). During saline substitutions, the effect of noncontingent MDMA (0.03-0.3 mg/kg) on response allocation was examined at each ambient temperature. RESULTS At room temperature, MDMA choice increased as a function of dose, such that food was preferred over a low MDMA dose (0.03 mg/kg/injection), whereas higher doses were preferred over food. Elevating the ambient temperature significantly increased the relative reinforcing strength of 0.03 mg/kg/injection MDMA, and lowering the ambient temperature significantly attenuated the choice of 0.1 mg/kg/injection MDMA. Noncontingent injections of MDMA administered before a session in which saline was the alternative to food dose-dependently increased injection-lever responding; this effect was not influenced by ambient temperature. CONCLUSIONS These results suggest that ambient temperature can affect the relative reinforcing strength of MDMA, but not MDMA-induced reinstatement. Furthermore, these results suggest environmental strategies for decreasing the reinforcing strength of MDMA.
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Affiliation(s)
- Matthew L. Banks
- Departments of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA 27157
| | - Jon E. Sprague
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, Ada, OH, USA 45810
| | - Paul W. Czoty
- Departments of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA 27157
| | - Michael A. Nader
- Departments of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA 27157
- Department of Radiology, Wake Forest University School of Medicine, Winston-Salem, NC, USA 27157
- * Corresponding Author: Michael A. Nader, Ph.D., Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Medical Center Blvd., NRC Room 546, Winston-Salem, NC 27157-1083, Phone: (336) 713-7172, Fax: (336) 713-7180,
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Schenk S, Hely L, Lake B, Daniela E, Gittings D, Mash DC. MDMA self-administration in rats: acquisition, progressive ratio responding and serotonin transporter binding. Eur J Neurosci 2007; 26:3229-36. [DOI: 10.1111/j.1460-9568.2007.05932.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ball KT, Walsh KM, Rebec GV. Reinstatement of MDMA (ecstasy) seeking by exposure to discrete drug-conditioned cues. Pharmacol Biochem Behav 2007; 87:420-5. [PMID: 17602729 PMCID: PMC2067991 DOI: 10.1016/j.pbb.2007.05.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 05/25/2007] [Accepted: 05/25/2007] [Indexed: 11/24/2022]
Abstract
The widely used recreational drug MDMA (ecstasy) supports self-administration in animals, but it is not known whether MDMA-associated cues are able to reinstate drug seeking in a relapse model of drug addiction. To assess this possibility, drug-naïve rats were trained to press a lever for MDMA infusions (0.30 mg/kg/infusion, i.v.) paired with a compound cue (light and tone) in daily 2 h sessions. Responding was reinforced contingent on a modified fixed-ratio 5 schedule of reinforcement. Conditioned cue-induced reinstatement tests were conducted after lever pressing was extinguished in the absence of MDMA and the conditioned cues. Conditioned cues reinstated lever pressing after extinction, and the magnitude of reinstatement was positively correlated with the level of responding during MDMA self-administration. These results show for the first time that conditioned cues can trigger reinstatement of MDMA-seeking behavior in rats, and that individual differences in the pattern of MDMA self-administration can predict the magnitude of reinstatement responding.
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Affiliation(s)
| | | | - George V. Rebec
- *Please Address Correspondence to: George V. Rebec, Department of Psychological and Brain Sciences and Program in Neuroscience, Indiana University, 1101 East 10 Street, Bloomington, IN 47405-7007, TEL: 812-855-4832, FAX: 812-855-4520,
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