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Abstract
In this Review, we consider the story of cocaine from its humble origins in South America to its status as one of the most abused substances in 21st century society. The synthesis and biosynthesis of cocaine are discussed, as well as its pharmacokinetics, metabolism, pharmacology, and importance in modern neuroscience and molecular imaging.
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Affiliation(s)
- Lindsey R. Drake
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48105, United States
| | - Peter J. H. Scott
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48105, United States
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2
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Brodnik ZD, Ferris MJ, Jones SR, España RA. Reinforcing Doses of Intravenous Cocaine Produce Only Modest Dopamine Uptake Inhibition. ACS Chem Neurosci 2017; 8:281-289. [PMID: 27936579 DOI: 10.1021/acschemneuro.6b00304] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The reinforcing efficacy of cocaine is thought to stem from inhibition of the dopamine transporter (DAT) and subsequent increases in extracellular dopamine concentrations in the brain. In humans, this hypothesis has generally been supported by positron emission tomography imaging studies where the percent of DATs occupied by cocaine is used as a measure of cocaine activity in the brain. Interpretation of these studies, however, often relies on the assumption that measures of DAT occupancy directly correspond with functional DAT blockade. In the current studies, we used in vivo and in vitro fast scan cyclic voltammetry in mice to measure dopamine uptake inhibition following varying doses of cocaine as well as two high affinity DAT inhibitors. We then compared dopamine clearance rates following these drug treatments to dopamine clearance obtained from DAT knockout mice as a proxy for complete DAT blockade. We found that administration of abused doses of cocaine resulted in approximately 2% of maximal DAT blockade. Overall, our data indicate that abused doses of cocaine produce a relatively modest degree of DA uptake inhibition, and suggest that the relationship between DAT occupancy and functional blockade of the DAT is more complex than originally posited.
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Affiliation(s)
- Zachary D. Brodnik
- Department
of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, United States
| | - Mark J. Ferris
- Department
of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina 27501, United States
| | - Sara R. Jones
- Department
of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina 27501, United States
| | - Rodrigo A. España
- Department
of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, United States
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3
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Kimura Y, Maeda J, Yamada M, Takahata K, Yokokawa K, Ikoma Y, Seki C, Ito H, Higuchi M, Suhara T. Measurement of psychological state changes at low dopamine transporter occupancy following a clinical dose of mazindol. Psychopharmacology (Berl) 2017; 234:323-328. [PMID: 27766370 DOI: 10.1007/s00213-016-4464-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 10/12/2016] [Indexed: 11/30/2022]
Abstract
RATIONALE The beneficial effects of psychostimulant drugs in the treatment of psychiatric disorders occur because they increase the extracellular dopamine concentration by inhibiting re-uptake of extracellular dopamine at dopamine transporters. However, the psychological effects at low dopamine transporter occupancy have not been well demonstrated. OBJECTIVES The purpose of the study was to evaluate the psychological effects, dopamine transporter occupancy, and dopamine release induced by a single oral administration of a clinical dose of mazindol. METHODS Ten healthy male volunteers were orally administered a placebo and a clinical dose of mazindol (1.5 mg) on separate days. The psychological effects of mazindol were assessed using a visual analogue scale to detect alterations in the state of consciousness. The amount of blockade of dopamine transporters was assessed using positron emission tomography with [18F]FE-PE2I and extracellular dopamine release was measured as the amount of change in [11C]raclopride binding. RESULTS Following administration of a clinical dose of mazindol, the dopamine transporters were blocked by 24-25 %, and the binding potential of [11C]raclopride was reduced by 2.8-4.6 %. The differences of a score measuring derealisation and depersonalization associated with a positive basic mood were significantly correlated with the change in the [11C]raclopride binding in the limbic striatum. CONCLUSIONS A subtle alteration in the state of consciousness was detected with a correlation to the changes in the [11C]raclopride binding, which implies that a subtle alteration in extracellular dopamine concentration in the limbic striatum by a small amount of dopamine transporter occupancy can affect the state of consciousness. TRIAL REGISTRATION HTTPS://UPLOAD.UMIN.AC.JP/CGI-OPEN-BIN/CTR_E/CTR_VIEW.CGI?RECPTNO=R000009703 : UMIN000008232.
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Affiliation(s)
- Y Kimura
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan. .,Department of Clinical and Experimental Neuroimaging Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan.
| | - J Maeda
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - M Yamada
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.,Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Saitama, Japan
| | - K Takahata
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - K Yokokawa
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Y Ikoma
- Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - C Seki
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - H Ito
- Department of Radiology and Nuclear Medicine, Fukushima Medical University, Fukushima, Japan
| | - M Higuchi
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - T Suhara
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
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4
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McIntosh S, Sexton T, Pattison LP, Childers SR, Hemby SE. Increased Sensitivity to Cocaine Self-Administration in HIV-1 Transgenic Rats is Associated with Changes in Striatal Dopamine Transporter Binding. J Neuroimmune Pharmacol 2015; 10:493-505. [PMID: 25749646 DOI: 10.1007/s11481-015-9594-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 02/13/2015] [Indexed: 12/14/2022]
Abstract
Cocaine abuse in HIV patients accelerates the progression and severity of neuropathology, motor impairment and cognitive dysfunction compared to non-drug using HIV patients. Cocaine and HIV interact with the dopamine transporter (DAT); however, the effect of their interaction on DAT binding remains understudied. The present study compared the dose-response functions for intravenous self-administration of cocaine and heroin between male HIV-1 transgenic (HIV-1 Tg) and Fischer 344 rats. The cocaine and heroin dose-response functions exhibit an inverted U-shape for both HIV-1 Tg and F344 rats. For cocaine, the number of infusions for each dose on the ascending limb was greater for HIV-1 Tg versus F344 rats. No significant changes in the heroin dose-response function were observed in HIV-1 Tg animals. Following the conclusion of self-administration experiments, DAT binding was assessed in striatal membranes. Saturation binding of the cocaine analog [(125)I] 3β-(4-iodophenyl)tropan-2β-carboxylic acid methyl ester ([(125)I]RTI-55) in rat striatal membranes resulted in binding curves that were best fit to a two-site binding model, allowing for calculation of dissociation constant (Kd) and binding density (Bmax) values that correspond to high- and low-affinity DAT binding sites. Control HIV-1 Tg rats exhibited a significantly greater affinity (i.e., decrease in Kd value) in the low-affinity DAT binding site compared to control F344 rats. Furthermore, cocaine self-administration in HIV-1 Tg rats increased low-affinity Kd (i.e., decreased affinity) compared to levels observed in control F344 rats. Cocaine also increased low-affinity Bmax in HIV-1 Tg rats as compared to controls, indicating an increase in the number of low-affinity DAT binding sites. F344 rats did not exhibit any change in high- or low-affinity Kd or Bmax values following cocaine or heroin self-administration. The increase in DAT affinity in cocaine HIV-1 Tg rats is consistent with the leftward shift of the ascending limb of the cocaine dose-response curve observed in HIV-1 Tg vs. F344 rats, and has major implications for the function of cocaine binding to DAT in HIV patients. The absence of HIV-related changes in heroin intake are likely due to less dopaminergic involvement in the mediation of heroin reward, further emphasizing the preferential influence of HIV on dopamine-related behaviors.
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Affiliation(s)
- Scot McIntosh
- Department of Physiology and Pharmacology, Center for the Neurobiology of Addiction Treatment, Winston-Salem, NC, USA
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5
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Richardson JR, Taylor MM, Shalat SL, Guillot TS, Caudle WM, Hossain MM, Mathews TA, Jones SR, Cory-Slechta DA, Miller GW. Developmental pesticide exposure reproduces features of attention deficit hyperactivity disorder. FASEB J 2015; 29:1960-72. [PMID: 25630971 DOI: 10.1096/fj.14-260901] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 12/22/2014] [Indexed: 12/25/2022]
Abstract
Attention-deficit hyperactivity disorder (ADHD) is estimated to affect 8-12% of school-age children worldwide. ADHD is a complex disorder with significant genetic contributions. However, no single gene has been linked to a significant percentage of cases, suggesting that environmental factors may contribute to ADHD. Here, we used behavioral, molecular, and neurochemical techniques to characterize the effects of developmental exposure to the pyrethroid pesticide deltamethrin. We also used epidemiologic methods to determine whether there is an association between pyrethroid exposure and diagnosis of ADHD. Mice exposed to the pyrethroid pesticide deltamethrin during development exhibit several features reminiscent of ADHD, including elevated dopamine transporter (DAT) levels, hyperactivity, working memory and attention deficits, and impulsive-like behavior. Increased DAT and D1 dopamine receptor levels appear to be responsible for the behavioral deficits. Epidemiologic data reveal that children aged 6-15 with detectable levels of pyrethroid metabolites in their urine were more than twice as likely to be diagnosed with ADHD. Our epidemiologic finding, combined with the recapitulation of ADHD behavior in pesticide-treated mice, provides a mechanistic basis to suggest that developmental pyrethroid exposure is a risk factor for ADHD.
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Affiliation(s)
- Jason R Richardson
- *Department of Environmental and Occupational Medicine and Environmental and Occupational Health Sciences Institute, Rutgers-Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA; Center for Neurodegenerative Disease, School of Medicine, and Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA; Department of Chemistry, Wayne State University, Detroit, Michigan, USA; and Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Michele M Taylor
- *Department of Environmental and Occupational Medicine and Environmental and Occupational Health Sciences Institute, Rutgers-Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA; Center for Neurodegenerative Disease, School of Medicine, and Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA; Department of Chemistry, Wayne State University, Detroit, Michigan, USA; and Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Stuart L Shalat
- *Department of Environmental and Occupational Medicine and Environmental and Occupational Health Sciences Institute, Rutgers-Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA; Center for Neurodegenerative Disease, School of Medicine, and Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA; Department of Chemistry, Wayne State University, Detroit, Michigan, USA; and Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Thomas S Guillot
- *Department of Environmental and Occupational Medicine and Environmental and Occupational Health Sciences Institute, Rutgers-Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA; Center for Neurodegenerative Disease, School of Medicine, and Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA; Department of Chemistry, Wayne State University, Detroit, Michigan, USA; and Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - W Michael Caudle
- *Department of Environmental and Occupational Medicine and Environmental and Occupational Health Sciences Institute, Rutgers-Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA; Center for Neurodegenerative Disease, School of Medicine, and Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA; Department of Chemistry, Wayne State University, Detroit, Michigan, USA; and Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Muhammad M Hossain
- *Department of Environmental and Occupational Medicine and Environmental and Occupational Health Sciences Institute, Rutgers-Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA; Center for Neurodegenerative Disease, School of Medicine, and Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA; Department of Chemistry, Wayne State University, Detroit, Michigan, USA; and Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Tiffany A Mathews
- *Department of Environmental and Occupational Medicine and Environmental and Occupational Health Sciences Institute, Rutgers-Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA; Center for Neurodegenerative Disease, School of Medicine, and Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA; Department of Chemistry, Wayne State University, Detroit, Michigan, USA; and Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Sara R Jones
- *Department of Environmental and Occupational Medicine and Environmental and Occupational Health Sciences Institute, Rutgers-Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA; Center for Neurodegenerative Disease, School of Medicine, and Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA; Department of Chemistry, Wayne State University, Detroit, Michigan, USA; and Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Deborah A Cory-Slechta
- *Department of Environmental and Occupational Medicine and Environmental and Occupational Health Sciences Institute, Rutgers-Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA; Center for Neurodegenerative Disease, School of Medicine, and Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA; Department of Chemistry, Wayne State University, Detroit, Michigan, USA; and Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York, USA
| | - Gary W Miller
- *Department of Environmental and Occupational Medicine and Environmental and Occupational Health Sciences Institute, Rutgers-Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA; Center for Neurodegenerative Disease, School of Medicine, and Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA; Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA; Department of Chemistry, Wayne State University, Detroit, Michigan, USA; and Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York, USA
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6
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Berridge MS, Apana SM, Nagano KK, Berridge CE, Leisure GP, Boswell MV. Smoking produces rapid rise of [11C]nicotine in human brain. Psychopharmacology (Berl) 2010; 209:383-94. [PMID: 20232056 DOI: 10.1007/s00213-010-1809-8] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Accepted: 02/17/2010] [Indexed: 11/29/2022]
Abstract
RATIONALE Variation in the rate at which drugs reach the brain influences many different drug effects and is also thought to influence liability to addiction. For example, rapid intravenous delivery of cocaine and nicotine is more effective in producing hedonic effects, tolerance, psychomotor sensitization, and in inducing gene expression. Smoking is thought to result in an especially rapid rate of rise of nicotine in the brain, but whether this is true has never been adequately addressed. Thus, in this study, we sought to determine the true rate of rise of smoked nicotine in human brain and compare this with previous intravenous nicotine delivery. METHODS Positron emission tomography scans of lung and brain regions and arterial and venous blood curves were obtained in human subjects after single puffs from cigarettes formulated with [(11)C]nicotine. RESULTS The rise of nicotine concentration following a single puff was rapid, reaching more than 50% of maximum brain levels within 15 s of bolus arrival in the brain in most subjects. This rate of rise was considerably faster than that seen in previous studies using intravenous administration. CONCLUSIONS Uptake in human brain from a single inhalation was sufficiently rapid that it is plausible that fast rate-of-rise contributes to nicotine dependence in smokers.
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Affiliation(s)
- Marc S Berridge
- 3D Imaging LLC, Cyclotron Suite Rm PS010, UAMS Radiology #556, 4301 W. Markham St., Little Rock, AR, 72205-7199, USA.
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7
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Apana SM, Berridge MS. Cigarettes labeled with [ 11C]nicotine: formulation and administration for PET inhalation. J Labelled Comp Radiopharm 2009. [DOI: 10.1002/jlcr.1692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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8
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Schiffer WK, Liebling CN, Patel V, Dewey SL. Targeting the treatment of drug abuse with molecular imaging. Nucl Med Biol 2007; 34:833-47. [DOI: 10.1016/j.nucmedbio.2007.05.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 04/30/2007] [Accepted: 05/12/2007] [Indexed: 11/25/2022]
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9
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Lee DE, Gerasimov MR, Schiffer WK, Gifford AN. Concentration-dependent conditioned place preference to inhaled toluene vapors in rats. Drug Alcohol Depend 2006; 85:87-90. [PMID: 16675162 DOI: 10.1016/j.drugalcdep.2006.03.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2005] [Revised: 03/13/2006] [Accepted: 03/17/2006] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Toluene is present in many commercial products and is subject to abuse by inhalation. The goal of this study was to extend previous reports indicating that rats will exhibit a positive conditioned place preference to inhaled toluene vapors and to determine the dose-response relationship for inhaled toluene in terms of exposure concentration and number of exposures. For the conditioned place preference experiments rats were exposed to toluene vapors at concentrations of 800, 2000, 3000 or 5000 ppm in one compartment of a three-compartment box. RESULTS Following six conditioning sessions with toluene, a significant place preference was obtained at 2000 and 3000 ppm, but not at 800 or 5000 ppm. Extending the number of toluene pairings at the 2000 and 3000 ppm concentration to 12 significantly enhanced the place preference compared to that at six pairings. CONCLUSIONS These experiments extend our previous finding that rats will show a conditioned place preference to inhaled toluene, and indicate that a reinforcing "dose" of toluene depends on both the concentration and number of pairings.
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Affiliation(s)
- Dianne E Lee
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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10
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Gelman BB, Spencer JA, Holzer CE, Soukup VM. Abnormal striatal dopaminergic synapses in National NeuroAIDS Tissue Consortium subjects with HIV encephalitis. J Neuroimmune Pharmacol 2006; 1:410-20. [PMID: 18040813 DOI: 10.1007/s11481-006-9030-6] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Accepted: 06/07/2006] [Indexed: 11/26/2022]
Abstract
People with human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) have neurological problems that overlap with diseases associated with abnormal dopaminergic (DAergic) synaptic transmission, including subcortical dementia, motor slowing, psychosis, and drug addiction. Previous study has suggested that DAergic tone may be decreased in HIV/AIDS, but biochemical confirmation of that tenet is still lacking. To that end, this study addresses the neurochemical interaction between HIV infection and DAergic synaptic transmission in human brain specimens. Protein markers of DAergic synapses were characterized in homogenates of the corpus striatum from individuals with HIV encephalitis (HIVE) and seronegative controls from the autopsy cohort of the National NeuroAIDS Tissue Consortium. Striatal DAergic markers were abnormal in HIVE. Abnormal presynaptic markers included decreased tyrosine hydroxylase (TH) protein and decreased phosphorylated TH. The presynaptic dopamine reuptake transporter (DAT) was increased reciprocally. Postsynaptic abnormalities included decreased dopamine receptor type 2 (D(2)R) and increased D(3)R. There was preferential loss of the alternatively spliced long isoform of D(2)R relative to the short isoform. Abnormal DAergic synapse proteins were significantly correlated with the HIV Gag mRNA transcripts amplified in striatal extracts. These synaptic changes resemble shifts that occur when DAergic tone is increased experimentally. Increased DAergic tone leads to heightened salience for drugs of abuse, increases behaviors that increase the risk of HIV transmission, and might decrease compliance with antiretroviral medication regimens.
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Affiliation(s)
- Benjamin B Gelman
- Department of Pathology, Route 0785, University of Texas Medical Branch, Galveston, Texas 77555-0785, USA.
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11
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Gerasimov MR, Ferrieri RA, Pareto D, Logan J, Alexoff D, Ding YS. Synthesis and evaluation of inhaled [11C]butane and intravenously injected [11C]acetone as potential radiotracers for studying inhalant abuse. Nucl Med Biol 2005; 32:201-8. [PMID: 15721766 DOI: 10.1016/j.nucmedbio.2004.11.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2004] [Revised: 10/22/2004] [Accepted: 11/10/2004] [Indexed: 11/15/2022]
Abstract
The phenomenon of inhalant abuse is a growing problem in the US and many countries around the world. Yet, relatively little is known about the pharmacokinetic properties of inhalants that underlie their abuse potential. While the synthesis of 11C-labeled toluene, acetone and butane has been proposed in the literature, none of these compounds has been developed as radiotracers for PET studies. In the present report we extend our previous studies with [11C]toluene to include [11C]acetone and [11C]butane with the goal of comparing the pharmacokinetic profiles of these three volatile abused substances. Both [11C]toluene and [11C]acetone were administered intravenously and [11C]butane was administered via inhalation to anesthesized baboons. Rapid and efficient uptake of radiolabeled toluene and acetone into the brain was followed by fast clearance in the case of toluene and slower kinetics in the case of acetone. [11C]Butane was detected in the blood and brain following inhalation, but the levels of radioactivity in both tissues dropped to half of the maximal values over the period of less than a minute. To our knowledge, this is the first reported study of the in vivo brain pharmacokinetics of labeled acetone and butane in nonhuman primates. These data provide insight into the pharmacokinetic features possibly associated with the abuse liability of toluene, acetone and butane.
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Affiliation(s)
- Madina R Gerasimov
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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12
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Desai RI, Kopajtic TA, French D, Newman AH, Katz JL. Relationship between in Vivo Occupancy at the Dopamine Transporter and Behavioral Effects of Cocaine, GBR 12909 [1-{2-[Bis-(4-fluorophenyl)methoxy]ethyl}-4-(3-phenylpropyl)piperazine], and Benztropine Analogs. J Pharmacol Exp Ther 2005; 315:397-404. [PMID: 16014753 DOI: 10.1124/jpet.105.091231] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Analogs of benztropine (BZT) bind to the dopamine (DA) transporter and inhibit DA uptake but often have behavioral effects that differ from those of cocaine and other DA-uptake inhibitors. To better understand these differences, we examined the relationship between locomotor-stimulant effects of cocaine, 1-{2-[bis-(4-fluorophenyl)methoxy]ethyl}-4-(3-phenylpropyl)-piperazine (GBR 12909), and BZT analogs [(3alpha-[bis(4'-fluorophenyl)methoxy]-tropane) (AHN 1-055) and (N-allyl-3alpha-[bis(4'-fluorophenyl)methoxy]-tropane) (AHN 2-005)] and their in vivo displacement of the DA transporter ligand [125I]3beta-(4-iodophenyl)-tropan-2beta-carboxylic acid isopropyl ester hydrochloride (RTI-121) in striatum. Cocaine, GBR 12909, and BZT analogs each displaced [125I]RTI-121 and stimulated locomotor activity in a dose- and time-dependent manner. The time course revealed a slower onset of both effects for AHN 1-055 and AHN 2-005 compared with cocaine and GBR 12909. The BZT analogs were less effective than cocaine and GBR 12909 in stimulating locomotor activity. Locomotor stimulant effects of cocaine were generally greater than predicted by the regression of displacement of [125I]RTI-121 and effect at short times after injection and less than predicted at longer times after injection. This result suggests that the apparent rate of occupancy of the DA transporter, in addition to percentage of sites occupied, contributes to the behavioral effects of cocaine. The present results suggest that among drugs that act at the DA transporter, the slower apparent rates of occupancy with the DA transporter by the BZT analogs may contribute in an important way to differences in their effectiveness.
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Affiliation(s)
- Rajeev I Desai
- Medication Discovery Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
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13
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Volkow ND, Wang GJ, Fowler JS, Learned-Coughlin S, Yang J, Logan J, Schlyer D, Gatley JS, Wong C, Zhu W, Pappas N, Schueller M, Jayne M, Carter P, Warner D, Ding YS, Shea C, Xu Y. The slow and long-lasting blockade of dopamine transporters in human brain induced by the new antidepressant drug radafaxine predict poor reinforcing effects. Biol Psychiatry 2005; 57:640-6. [PMID: 15780851 DOI: 10.1016/j.biopsych.2004.12.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2004] [Revised: 11/29/2004] [Accepted: 12/04/2004] [Indexed: 11/24/2022]
Abstract
BACKGROUND (2S,3S)-2-(3-Chlorophenyl)-3,5,5,-trimethyl-2-morpholinol hydrochloride (radafaxine) is a new antidepressant that blocks dopamine transporters (DAT). A concern with drugs that block (DAT) is their potential reinforcing effects and abuse liability. Using positron emission tomography (PET) we have shown that for DAT-blocking drugs to produce reinforcing effects they must induce >50% DAT blockade and the blockade has to be fast (within 15 minutes). This study measures the potency and kinetics for DAT blockade by radafaxine in human brain. METHODS PET and [11C]cocaine were used to estimate DAT blockade at 1, 4, 8, and 24 hours after radafaxine (40 mg p.o.) in 8 controls. Plasma pharmacokinetics and behavioral and cardiovascular effects were measured in parallel. RESULTS DAT blockade by radafaxine was slow, and at 1 hour, it was 11%. Peak blockade occurred at about 4 hours and was 22%. Blockade was long lasting: at 8 hours 17%, and at 24 hours 15%. Peak plasma concentration occurred about 4 to 8 hours. No behavioral or cardiovascular effects were observed. CONCLUSIONS The relatively low potency of radafaxine in blocking DAT and its slow blockade suggests that it is unlikely to have reinforcing effects. This is consistent with preclinical studies showing no self-administration. This is the first utilization of PET to predict abuse liability of a new antidepressant in humans based on DAT occupancy and pharmacokinetics.
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Affiliation(s)
- Nora D Volkow
- Brookhaven National Laboratory, Upton, NY 11973, USA.
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14
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Volkow ND, Fowler JS, Wang GJ, Swanson JM. Dopamine in drug abuse and addiction: results from imaging studies and treatment implications. Mol Psychiatry 2004; 9:557-69. [PMID: 15098002 DOI: 10.1038/sj.mp.4001507] [Citation(s) in RCA: 596] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The involvement of dopamine in drug reinforcement is well recognized but its role in drug addiction is much less clear. Imaging studies have shown that the reinforcing effects of drugs of abuse in humans are contingent upon large and fast increases in dopamine that mimic but exceed in the intensity and duration those induced by dopamine cell firing to environmental events. In addition, imaging studies have also documented a role of dopamine in motivation, which appears to be encoded both by fast as well as smooth DA increases. Since dopamine cells fire in response to salient stimuli, the supraphysiological activation by drugs is likely to be experienced as highly salient (driving attention, arousal conditioned learning and motivation) and may also reset the thresholds required for environmental events to activate dopamine cells. Indeed, imaging studies have shown that in drug-addicted subjects, dopamine function is markedly disrupted (decreases in dopamine release and in dopamine D2 receptors in striatum) and this is associated with reduced activity of the orbitofrontal cortex (neuroanatomical region involved with salience attribution and motivation and implicated in compulsive behaviors) and the cingulate gyrus (neuroanatomical region involved with inhibitory control and attention and implicated in impulsivity). However, when addicted subjects are exposed to drug-related stimuli, these hypoactive regions become hyperactive in proportion to the expressed desire for the drug. We postulate that decreased dopamine function in addicted subjects results in decreased sensitivity to nondrug-related stimuli (including natural reinforcers) and disrupts frontal inhibition, both of which contribute to compulsive drug intake and impaired inhibitory control. These findings suggest new strategies for pharmacological and behavioral treatments, which focus on enhancing DA function and restoring brain circuits disrupted by chronic drug use to help motivate the addicted subject in activities that provide alternative sources of reinforcement, counteract conditioned responses, enhance their ability to control their drive to take drugs and interfere with their compulsive administration.
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Affiliation(s)
- N D Volkow
- National Institute on Drug Abuse, Bethesda, MD 20892, USA. nvolkow@nida
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15
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Abstract
Neuroimaging techniques, including positron emission tomography (PET), are ideally suited for studies of addiction. These minimally invasive modalities yield information about acute and long-term drug-induced structural and functional changes in the brain over time. Changes can be observed in the brains of human and animal subjects during drug self-administration. Neuroimaging with PET allows precise quantification and visualization of the drug and its rates of movement in the body. In addition, imaging reveals recovery of function and reappearance of neuronal markers in abstinent drug users. Evidence that suggests that PET may have use in identifying individuals predisposed to become addicted is emerging. Finally, candidate pharmacotherapies for drug addiction can be critically evaluated. These unique assets clearly point to the use of these strategies for addiction studies.
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Affiliation(s)
- Kimberly P Lindsey
- Medical Department, Brookhaven National Laboratory, Building 490, Upton, NY 11973, USA.
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16
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Matsumoto RR, McCracken KA, Pouw B, Zhang Y, Bowen WD. Involvement of sigma receptors in the behavioral effects of cocaine: evidence from novel ligands and antisense oligodeoxynucleotides. Neuropharmacology 2002; 42:1043-55. [PMID: 12128006 DOI: 10.1016/s0028-3908(02)00056-4] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Pharmacological and molecular biological tools were used to validate the involvement of sigma receptors in the actions of cocaine. Radioligand binding studies demonstrated significant levels of sigma receptors in the brain and heart, where cocaine interacts preferentially with the sigma(1) subtype. In behavioral pharmacological studies using mice, nine novel sigma receptor antagonists significantly attenuated cocaine-induced convulsions, while structural analogs with weak interactions with sigma receptors were ineffective. In contrast to the protection provided by the antagonists, a classical sigma receptor agonist exacerbated the convulsive effects of cocaine. The antagonists also attenuated cocaine-induced lethality, with the best compound protecting against death even when administered as a post-treatment. At doses where the antagonists had no effect on baseline locomotor activity, they significantly attenuated the locomotor stimulatory effects of cocaine, suggesting their ability to block the psychomotor as well as the toxic effects of cocaine. To further validate that the anti-cocaine effects were achieved by interfering with cocaine's access to sigma receptors, antisense oligodeoxynucleotides against sigma(1) receptors were shown to attenuate the convulsive and locomotor stimulatory effects of cocaine. Together, the studies support the involvement of sigma receptors, particularly the sigma(1) subtype, in the behavioral effects of cocaine.
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Affiliation(s)
- Rae R Matsumoto
- Department of Pharmaceutical Sciences, P.O. Box 26901, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, USA.
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17
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Gerasimov MR, Ferrieri RA, Schiffer WK, Logan J, Gatley SJ, Gifford AN, Alexoff DA, Marsteller DA, Shea C, Garza V, Carter P, King P, Ashby CR, Vitkun S, Dewey SL. Study of brain uptake and biodistribution of [11C]toluene in non-human primates and mice. Life Sci 2002; 70:2811-28. [PMID: 12269385 DOI: 10.1016/s0024-3205(02)01542-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inhalant abuse is a rapidly growing health problem particularly among adolescents. Yet we know little about the neural mechanisms underlying the abuse liability of inhalants, particularly when compared to other addictive drugs. Specifically, our understanding of the relationship between the regional brain phamacokinetics and features classically associated with drug reinforcement is lacking. Under the hypothesis that the abuse liability of toluene can be related to its pharmacokinetic properties and the pattern of regional brain uptake, we developed the methodology for radiolabeling and purifying [11C]toluene for use in PET studies. Here we report the regional brain distribution and kinetics of the widely abused solvent toluene in non-human primates and the whole body biodistribution in mice. To our knowledge, this is the first reported study of the in vivo brain pharmacokinetics of labeled toluene in non-human primates. Rapid uptake of radioactivity into striatal and frontal regions was followed by rapid clearance from the brain. Concurrent findings in rodents indicate similar radio-tracer kinetics, with excretion through kidneys and liver. Taken together, our data provides insight into pharmacokinetic features possibly associated with the abuse liability of toluene.
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Affiliation(s)
- M R Gerasimov
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
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18
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Fowler JS, Volkow ND, Wang GJ, Gatley SJ, Logan J. [(11)]Cocaine: PET studies of cocaine pharmacokinetics, dopamine transporter availability and dopamine transporter occupancy. Nucl Med Biol 2001; 28:561-72. [PMID: 11516700 DOI: 10.1016/s0969-8051(01)00211-6] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Cocaine was initially labeled with carbon-11 in order to track the distribution and pharmacokinetics of this powerful stimulant and drug of abuse in the human brain and body. It was soon discovered that [(11)C]cocaine was not only useful for measuring cocaine pharmacokinetics and its relationship to behavior but that it is also a sensitive radiotracer for dopamine transporter (DAT) availability. Measures of DAT availability were facilitated by the development of a graphical analysis method (Logan Plot) for reversible systems which streamlined kinetic analysis. This expanded the applications of [(11)C]cocaine to studies of DAT availability in the human brain and allowed the first comparative measures of the degree of DAT occupancy by cocaine and another stimulant drug methylphenidate. This article will summarize preclinical and clinical research with [(11)C]cocaine.
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Affiliation(s)
- J S Fowler
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
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19
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Matsumoto RR, McCracken KA, Friedman MJ, Pouw B, De Costa BR, Bowen WD. Conformationally restricted analogs of BD1008 and an antisense oligodeoxynucleotide targeting sigma1 receptors produce anti-cocaine effects in mice. Eur J Pharmacol 2001; 419:163-74. [PMID: 11426838 DOI: 10.1016/s0014-2999(01)00968-2] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cocaine's ability to interact with sigma receptors suggests that these proteins mediate some of its behavioral effects. Therefore, three novel sigma receptor ligands with antagonist activity were evaluated in Swiss Webster mice: BD1018 (3S-1-[2-(3,4-dichlorophenyl)ethyl]-1,4-diazabicyclo[4.3.0]nonane), BD1063 (1-[2-(3,4-dichlorophenyl)ethyl]-4-methylpiperazine), and LR132 (1R,2S-(+)-cis-N-[2-(3,4-dichlorophenyl)ethyl]-2-(1-pyrrolidinyl)cyclohexylamine). Competition binding assays demonstrated that all three compounds have high affinities for sigma1 receptors. The three compounds vary in their affinities for sigma2 receptors and exhibit negligible affinities for dopamine, opioid, GABA(A) and NMDA receptors. In behavioral studies, pre-treatment of mice with BD1018, BD1063, or LR132 significantly attenuated cocaine-induced convulsions and lethality. Moreover, post-treatment with LR132 prevented cocaine-induced lethality in a significant proportion of animals. In contrast to the protection provided by the putative antagonists, the well-characterized sigma receptor agonist di-o-tolylguanidine (DTG) and the novel sigma receptor agonist BD1031 (3R-1-[2-(3,4-dichlorophenyl)ethyl]-1,4-diazabicyclo[4.3.0]nonane) each worsened the behavioral toxicity of cocaine. At doses where alone, they produced no significant effects on locomotion, BD1018, BD1063 and LR132 significantly attenuated the locomotor stimulatory effects of cocaine. To further validate the hypothesis that the anti-cocaine effects of the novel ligands involved antagonism of sigma receptors, an antisense oligodeoxynucleotide against sigma1 receptors was also shown to significantly attenuate the convulsive and locomotor stimulatory effects of cocaine. Together, the data suggests that functional antagonism of sigma receptors is capable of attenuating a number of cocaine-induced behaviors.
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Affiliation(s)
- R R Matsumoto
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA.
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20
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Matsumoto RR, McCracken KA, Pouw B, Miller J, Bowen WD, Williams W, De Costa BR. N-alkyl substituted analogs of the sigma receptor ligand BD1008 and traditional sigma receptor ligands affect cocaine-induced convulsions and lethality in mice. Eur J Pharmacol 2001; 411:261-73. [PMID: 11164383 DOI: 10.1016/s0014-2999(00)00917-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Cocaine binds to sigma receptors with comparable affinity to its well-established interaction with dopamine transporters. Previous studies have shown BD1008 (N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)ethylamine) to have high affinity and selectivity for sigma receptors, and to additionally attenuate the locomotor stimulatory effects of cocaine. Therefore, in the present study, three N-alkyl substituted analogs of BD1008 were characterized in receptor binding and behavioral studies: BD1060 (N-[2-(3,4-dichlorophenyl)ethyl]-2-(1-pyrrolidinyl)ethylamine), BD1067 (N-[2-(3,4-dichlorophenyl)ethyl]-N-ethyl-2-(1-pyrrolidinyl)ethylamine), and BD1052 (N-[2-(3,4-dichlorophenyl)ethyl]-N-allyl-2-(1-pyrrolidinyl)ethylamine). Similarly to BD1008, all three analogs exhibited high affinity and selectivity for sigma receptors. In behavioral studies, BD1008, BD1060 or BD1067 attenuated cocaine-induced convulsions and lethality in Swiss Webster mice. The protective effects appear to be mediated through sigma receptor antagonism because traditional sigma receptor antagonists with high to moderate affinity for these receptors also attenuated the behavioral toxicity of cocaine. In contrast, traditional and novel sigma receptor agonists such as di-o-tolylguanidine and BD1052 worsened the behavioral toxicity of cocaine. To further characterize the actions of the N-alkyl substituted compounds, they were microinjected into the rat red nucleus, a functional assay of sigma receptor activity, where they produced agonist vs. antagonist actions that were consistent with their effects on cocaine-induced behaviors. Together, the data demonstrate that BD1008, BD1060 or BD1067 can attenuate the behavioral toxicity of cocaine, most likely through functional antagonism of sigma receptors.
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Affiliation(s)
- R R Matsumoto
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Oklahoma Health Sciences Center, P.O. Box 26901, Oklahoma City, OK 73190, USA.
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21
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Gerasimov MR, Franceschi M, Volkow ND, Rice O, Schiffer WK, Dewey SL. Synergistic interactions between nicotine and cocaine or methylphenidate depend on the dose of dopamine transporter inhibitor. Synapse 2000; 38:432-7. [PMID: 11044890 DOI: 10.1002/1098-2396(20001215)38:4<432::aid-syn8>3.0.co;2-q] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
There is a greater prevalence of cigarette smoking among cocaine-dependent individuals and hyperactive children treated with stimulants (e.g., methylphenidate, MP). However, little is known about the neurochemical basis of the interaction between nicotine and cocaine or MP. It is thought that the reinforcing effects of cocaine and MP are due partly to increases in synaptic DA in the nucleus accumbens (NAc). These measurable increases are secondary to the blockade of the DA transporter. In contrast, nicotine stimulates acetylcholine receptors located presynaptically on dopaminergic projections from the ventral tegmental area (VTA) to the NAc and increases DA transmission. Here we investigate the effects of nicotine on NAc DA in animals simultaneously injected with cocaine or MP. Coadministration of nicotine (0.4 mg/kg s.c.) and cocaine (10 mg/kg i.p.) or MP (5 mg/kg i.p.) increased the extracellular NAc DA levels in an additive manner, while coadministration of nicotine (0. 4 mg/kg s.c.) and a higher dose of cocaine (20 mg/kg) or MP (10 mg/kg) clearly produced a synergistic elevation in NAc DA. These findings suggest that the degree of DA transporter (DAT) occupancy contributes to the synergistic interaction between nicotine and cocaine or MP.
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Affiliation(s)
- M R Gerasimov
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
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22
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Abstract
The cost to society of alcohol, tobacco, and illicit drug dependence is enormous. Although the importance of treatment for substance abuse to public health is increasingly acknowledged, pharmacotherapy is generally underutilized. However, the selection of medications for clinical testing is increasingly guided by the rapidly evolving science of addictive drugs and behavior. The benefit of medication for smoking cessation is firmly established, particularly for nicotine replacement and antidepressant therapy. Naltrexone is an important addition to the pharmacopoeia, and acamprosate may soon be approved as well. Although no new medications are approved for cocaine and amphetamine abuse, a variety of candidate treatments have shown promise in ongoing studies. Opiate substitution therapy is highly effective for rehabilitation of heroin addiction, and several alternative forms will soon be available; alternative forms of opiate detoxification have also received attention. Overall, there is increasing recognition that physicians have an obligation to identify and treat all forms of substance dependence, although knowledge of the efficacy of the available treatments is steadily increasing.
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Affiliation(s)
- P C Gottschalk
- Veteran's Affairs Medical Center 116-A, 950 Campbell Avenue, West Haven, CT 06516, USA
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23
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Dewey SL, Morgan AE, Ashby CR, Horan B, Kushner SA, Logan J, Volkow ND, Fowler JS, Gardner EL, Brodie JD. A novel strategy for the treatment of cocaine addiction. Synapse 1998; 30:119-29. [PMID: 9723781 DOI: 10.1002/(sici)1098-2396(199810)30:2<119::aid-syn1>3.0.co;2-f] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Cocaine's addictive liability has been linked to its pharmacologic actions on mesotelencephalic dopamine (DA) reinforcement/reward pathways in the central nervous system (CNS). Dopaminergic transmission within these pathways is modulated by gamma-aminobutyric acid (GABA). With this knowledge, we examined the utility of gamma vinylGABA (GVG), a selective and irreversible inhibitor of GABA-transaminase (GABA-T) known to potentiate GABAergic inhibition, to alter cocaine's biochemical effects as well as its effects on behaviors associated with these biochemical changes. GVG significantly attenuated cocaine-induced increases in neostriatal synaptic DA in the non-human primate (baboon) brain as assessed by positron emission tomography (PET) and abolished both the expression and acquisition of cocaine-induced conditioned place preference (CPP). It had no effect on CPP for a food reward, the delivery of cocaine to the brain or locomotor activity. These findings suggest the possible therapeutic utility in cocaine addiction of a pharmacologic strategy targeted at the GABAergic neurotransmitter system, a system distinct from but functionally linked to the DA mesotelencephalic reward/reinforcement system. However, rather than targeting the GABA receptor complex with a direct GABA agonist, this novel approach with GVG takes advantage of the prolonged effects of an irreversible enzyme inhibitor that raises endogenous GABA levels without the addictive liability associated with GABA agonists acting directly at the receptor itself. Human trials with GVG are currently being developed to directly examine the utility of this novel strategy for the treatment of cocaine addiction.
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Affiliation(s)
- S L Dewey
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
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24
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Fowler JS, Volkow ND. PET imaging studies in drug abuse. JOURNAL OF TOXICOLOGY. CLINICAL TOXICOLOGY 1998; 36:163-74. [PMID: 9656971 DOI: 10.3109/15563659809028936] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
UNLABELLED In spite of the massive public health problem associated with drug abuse, effective treatments remain elusive. This is due in part to a relatively poor understanding of the neurochemical changes which drugs of abuse produce in the human brain and the relationship of these changes to the behavioral and addictive properties of drugs. With the development of modern imaging methods and a variety of labeled drugs and radiotracers, it has now become possible to track many aspects of drug pharmacokinetics and pharmacodynamics directly in the human brain and to relate these parameters to the behavioral and toxic properties of drugs. REVIEW In this article, we will highlight some examples of the use of Positron Emission Tomography to measure drug pharmacokinetics and pharmacodynamics and their relationship to addiction and to toxicity.
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Affiliation(s)
- J S Fowler
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
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Fowler JS, Volkow ND, Logan J, Gatley SJ, Pappas N, King P, Ding YS, Wang GJ. Measuring dopamine transporter occupancy by cocaine in vivo: radiotracer considerations. Synapse 1998; 28:111-6. [PMID: 9450511 DOI: 10.1002/(sici)1098-2396(199802)28:2<111::aid-syn1>3.0.co;2-e] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Several recent neuroimaging studies in humans and in monkeys using different radiotracers have reported widely differing values of dopamine transporter (DAT) occupancy by doses of cocaine which are perceived as reinforcing by humans. Here we tested the hypothesis that the measurement of DAT occupancies by drugs with fast pharmacokinetics such as cocaine requires a radioligand with similar kinetics in order to effectively compete with the drug. We measured DAT occupancy by four different doses of cocaine (1.0, 0.5, 0.25, and 0.1 mg/kg) using [11C]d-threo-methylphenidate (a radiotracer which binds rapidly to the DAT in vivo) and compared them to estimates reported previously using [11C]cocaine in the same two baboons and with the same four doses of cocaine [Volkow et al. (1996b) Synapse 24:399-402). Cocaine reduced [11C]d-threo-methylphenidate binding in striatum in a dose-dependent manner, and values were significantly correlated with those obtained previously with [11C]cocaine (r = 0.9, F = 37, P < 0.001). The ED50s (50% occupancy of DAT by cocaine) were 0.27 and 0.17 mg/kg for [11C]d-threo-methylphenidate and [11C]cocaine, respectively. This is significantly lower than values obtained with labeled beta-CIT and other similar radiotracers with a slow uptake and clearance (ED50s: 3-7 mg/kg). We conclude that in vivo measurements of DAT occupancy by rapidly clearing drugs like cocaine requires the use of radiotracers having similar kinetics to the drug itself.
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Affiliation(s)
- J S Fowler
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
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Morgan AE, Porter SP, Clarkson FA, Volkow ND, Fowler JS, Dewey SL. Direct approach for attenuating cocaine's effects on extracellular dopamine: targeting the dopamine transporter. Synapse 1997; 26:423-7. [PMID: 9215601 DOI: 10.1002/(sici)1098-2396(199708)26:4<423::aid-syn10>3.0.co;2-u] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Using in vivo microdialysis techniques, the effects of RTI-55 and/or cocaine on extracellular dopamine (DA) concentrations were measured in the nucleus accumbens (NACC) of freely moving rats. In control animals, cocaine (20 mg/kg) increased NACC DA approximately 458% 60 minutes following administration, returning to baseline values within 200 minutes. Similarly, RTI-55 administration (0.25 mg/kg) increased NACC DA levels approximately 347%. When combined, however, cocaine further increased NACC DA to 705% of baseline values when given 4 hours following RTI-55. This increase was significantly larger than cocaine alone (P < 0.05). In addition, chronic RTI-55 administration (5 days) further potentiated cocaine's ability to increase NACC DA (783%) but this did not reach statistical significance (P > 0.1) compared to acute RTI55/cocaine animals. These findings indicate that RTI-55, a drug that binds directly to the dopamine transporter (DAT) with higher affinity than cocaine, does not appear to be effective in attenuating cocaine's effects on NACC dopamine levels. In fact, acute RTI-55 potentiates cocaine's effects on NACC DA.
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Affiliation(s)
- A E Morgan
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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27
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Volkow ND, Wang GJ, Fischman MW, Foltin RW, Fowler JS, Abumrad NN, Vitkun S, Logan J, Gatley SJ, Pappas N, Hitzemann R, Shea CE. Relationship between subjective effects of cocaine and dopamine transporter occupancy. Nature 1997; 386:827-30. [PMID: 9126740 DOI: 10.1038/386827a0] [Citation(s) in RCA: 405] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Cocaine is believed to work by blocking the dopamine transporter (DAT) and thereby increasing the availability of free dopamine within the brain. Although this concept is central to current cocaine research and to treatment development, a direct relationship between DAT blockade and the subjective effects of cocaine has not been demonstrated in humans. We have used positron emission tomography to determine what level of DAT occupancy is required to produce a subjective 'high' in human volunteers who regularly abuse cocaine. We report here that intravenous cocaine at doses commonly abused by humans (0.3-0.6 mg kg(-1)) blocked between 60 and 77% of DAT sites in these subjects. The magnitude of the self-reported high was correlated with the degree of DAT occupancy, and at least 47% of the transporters had to be blocked for subjects to perceive cocaine's effects. Furthermore, the time course for the high paralleled that of cocaine concentration within the striatum, a brain region implicated in the control of motivation and reward. This is the first demonstration in humans that the doses used by cocaine abusers lead to significant blockade of DAT, and that this blockade is associated with the subjective effects of cocaine. Although these findings provide justification to target the DAT for medication development they suggest that for drugs to be effective in blocking cocaine's effects they would have to be given at doses that achieve almost complete DAT occupancy.
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Affiliation(s)
- N D Volkow
- Medical Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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