1
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Lupica CR, Hoffman AF. Control of dopamine communication by opioids: glutamate enters the discussion. Neuropsychopharmacology 2023; 48:1833-1834. [PMID: 37500722 PMCID: PMC10584928 DOI: 10.1038/s41386-023-01683-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 07/18/2023] [Indexed: 07/29/2023]
Affiliation(s)
- Carl R Lupica
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program, Computational and Systems Neuroscience Branch, Electrophysiology Research Section, Baltimore, MD, 21224, USA
| | - Alexander F Hoffman
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program, Computational and Systems Neuroscience Branch, Electrophysiology Research Section, Baltimore, MD, 21224, USA.
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2
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Yano H, Chitsazi R, Lucaj C, Tran P, Hoffman AF, Baumann MH, Lupica CR, Shi L. Subtle Structural Modification of a Synthetic Cannabinoid Receptor Agonist Drastically Increases its Efficacy at the CB1 Receptor. ACS Chem Neurosci 2023; 14:3928-3940. [PMID: 37847546 PMCID: PMC10623572 DOI: 10.1021/acschemneuro.3c00530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 09/26/2023] [Indexed: 10/18/2023] Open
Abstract
The emergence of synthetic cannabinoid receptor agonists (SCRAs) as illicit psychoactive substances has posed considerable public health risks, including fatalities. Many SCRAs exhibit much higher efficacy and potency compared with the phytocannabinoid Δ9-tetrahydrocannabinol (THC) at the cannabinoid receptor 1 (CB1R), leading to dramatic differences in signaling levels that can be toxic. In this study, we investigated the structure-activity relationships of aminoalkylindole SCRAs at CB1Rs, focusing on 5F-pentylindoles containing an amide linker attached to different head moieties. Using in vitro bioluminescence resonance energy transfer assays, we identified a few SCRAs exhibiting significantly higher efficacy in engaging the Gi protein and recruiting β-arrestin than the reference CB1R full agonist CP55940. Importantly, the extra methyl group on the head moiety of 5F-MDMB-PICA, as compared to that of 5F-MMB-PICA, led to a large increase in efficacy and potency at the CB1R. This pharmacological observation was supported by the functional effects of these SCRAs on glutamate field potentials recorded in hippocampal slices. Molecular modeling and simulations of the CB1R models bound with both of the SCRAs revealed critical structural determinants contributing to the higher efficacy of 5F-MDMB-PICA and how these subtle differences propagated to the receptor-G protein interface. Thus, we find that apparently minor structural changes in the head moiety of SCRAs can cause major changes in efficacy. Our results highlight the need for close monitoring of the structural modifications of newly emerging SCRAs and their potential for toxic drug responses in humans.
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Affiliation(s)
- Hideaki Yano
- Department
of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical
Sciences, Bouvé College of Health Sciences, Center for Drug
Discovery, Northeastern University, Boston, Massachusetts 02115, United States
| | - Rezvan Chitsazi
- Computational
Chemistry and Molecular Biophysics Section, National Institutes of Health, Baltimore, Maryland 21224, United States
| | - Christopher Lucaj
- Department
of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical
Sciences, Bouvé College of Health Sciences, Center for Drug
Discovery, Northeastern University, Boston, Massachusetts 02115, United States
| | - Phuong Tran
- Computational
Chemistry and Molecular Biophysics Section, National Institutes of Health, Baltimore, Maryland 21224, United States
| | - Alexander F. Hoffman
- Electrophysiology
Research Section, National Institutes of
Health, Baltimore, Maryland 21224, United States
| | - Michael H. Baumann
- Designer
Drug Research Unit, Intramural Research Program, National Institute
on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, United States
| | - Carl R. Lupica
- Electrophysiology
Research Section, National Institutes of
Health, Baltimore, Maryland 21224, United States
| | - Lei Shi
- Computational
Chemistry and Molecular Biophysics Section, National Institutes of Health, Baltimore, Maryland 21224, United States
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Yano H, Chitsazi R, Lucaj C, Tran P, Hoffman AF, Baumann MH, Lupica CR, Shi L. A subtle structural modification of a synthetic cannabinoid receptor agonist drastically increases its efficacy at the CB1 receptor. bioRxiv 2023:2023.06.10.544442. [PMID: 37398099 PMCID: PMC10312643 DOI: 10.1101/2023.06.10.544442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The emergence of synthetic cannabinoid receptor agonists (SCRAs) as illicit psychoactive substances has posed considerable public health risks that include fatalities. Many SCRAs exhibit much higher efficacy and potency, compared with the phytocannabinoid Δ9-tetrahydrocannabinol (THC), at the cannabinoid receptor 1 (CB1R), a G protein-coupled receptor involved in modulating neurotransmitter release. In this study, we investigated structure activity relationships (SAR) of aminoalkylindole SCRAs at CB1Rs, focusing on 5F-pentylindoles containing an amide linker attached to different head moieties. Using in vitro bioluminescence resonance energy transfer (BRET) assays, we identified a few of SCRAs exhibiting significantly higher efficacy in engaging the Gi protein and recruiting β-arrestin than the reference CB1R full agonist CP55940. Importantly, adding a methyl group at the head moiety of 5F-MMB-PICA yielded 5F-MDMB-PICA, an agonist exhibiting a large increase in efficacy and potency at the CB1R. This pharmacological observation was supported by a functional assay of the effects of these SCRAs on glutamate field potentials recorded in hippocampal slices. Molecular modeling and simulations of the CB1R bound with either of the SCRAs revealed critical structural determinants contributing to the higher efficacy of 5F-MDMB-PICA, and how these subtle differences propagated to the receptor-G protein interface. Thus, we find that apparently minor structural changes in the head moiety of SCRAs can cause major changes in efficacy. Our results highlight the need for close monitoring of structural modifications of newly emerging SCRAs and their potential for toxic drug responses in humans.
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Affiliation(s)
- Hideaki Yano
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Center for Drug Discovery, Northeastern University
| | - Rezvan Chitsazi
- Computational Chemistry and Molecular Biophysics Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224
| | - Christopher Lucaj
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Center for Drug Discovery, Northeastern University
| | - Phuong Tran
- Computational Chemistry and Molecular Biophysics Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224
| | - Alexander F Hoffman
- Electrophysiology Research Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224
| | - Michael H Baumann
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224
| | - Carl R Lupica
- Electrophysiology Research Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224
| | - Lei Shi
- Computational Chemistry and Molecular Biophysics Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224
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4
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Niello M, Sideromenos S, Gradisch R, O´Shea R, Schwazer J, Maier J, Kastner N, Sandtner W, Jäntsch K, Lupica CR, Hoffman AF, Lubec G, Loland CJ, Stockner T, Pollak DD, Baumann MH, Sitte HH. Persistent binding at dopamine transporters determines sustained psychostimulant effects. Proc Natl Acad Sci U S A 2023; 120:e2114204120. [PMID: 36730201 PMCID: PMC9963675 DOI: 10.1073/pnas.2114204120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 12/28/2022] [Indexed: 02/03/2023] Open
Abstract
Psychostimulants interacting with the dopamine transporter (DAT) can be used illicitly or for the treatment of specific neuropsychiatric disorders. However, they can also produce severe and persistent adverse events. Often, their pharmacological properties in vitro do not fully correlate to their pharmacological profile in vivo. Here, we investigated the pharmacological effects of enantiomers of pyrovalerone, α-pyrrolidinovalerophenone, and 3,4-methylenedioxypyrovalerone as compared to the traditional psychostimulants cocaine and methylphenidate, using a variety of in vitro, computational, and in vivo approaches. We found that in vitro drug-binding kinetics at DAT correlate with the time-course of in vivo psychostimulant action in mice. In particular, a slow dissociation (i.e., slow koff) of S-enantiomers of pyrovalerone analogs from DAT predicts their more persistent in vivo effects when compared to cocaine and methylphenidate. Overall, our findings highlight the critical importance of drug-binding kinetics at DAT for determining the in vivo profile of effects produced by psychostimulant drugs.
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Affiliation(s)
- Marco Niello
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Spyridon Sideromenos
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Ralph Gradisch
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Ronan O´Shea
- Electrophysiology Research Section, National Institute on Drug Abuse, NIH, Baltimore, MD21224
| | - Jakob Schwazer
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Julian Maier
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Nina Kastner
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Walter Sandtner
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Kathrin Jäntsch
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Carl R. Lupica
- Electrophysiology Research Section, National Institute on Drug Abuse, NIH, Baltimore, MD21224
| | - Alexander F. Hoffman
- Electrophysiology Research Section, National Institute on Drug Abuse, NIH, Baltimore, MD21224
| | - Gert Lubec
- Department of Neuroproteomics, Paracelsus Medical University, 5020Salzburg, Austria
| | - Claus J. Loland
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200Copenhagen, Denmark
| | - Thomas Stockner
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Daniela D. Pollak
- Center for Physiology and Pharmacology, Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, 1090Vienna, Austria
| | - Michael H. Baumann
- Designer Drug Research Unit, Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD21224
| | - Harald H. Sitte
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, 1090Vienna, Austria
- AddRess, Center for Addiction Research and Science, Medical University of Vienna, 1090Vienna, Austria
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Wolfe CIC, Hwang EK, Ijomor EC, Zapata A, Hoffman AF, Lupica CR. Muscarinic Acetylcholine M 2 Receptors Regulate Lateral Habenula Neuron Activity and Control Cocaine Seeking Behavior. J Neurosci 2022; 42:5552-5563. [PMID: 35764382 PMCID: PMC9295832 DOI: 10.1523/jneurosci.0645-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/12/2022] [Accepted: 05/29/2022] [Indexed: 01/16/2023] Open
Abstract
The lateral habenula (LHb) balances reward and aversion by opposing activation of brain reward nuclei and is involved in the inhibition of responding for cocaine in a model of impulsive behavior. Previously, we reported that the suppression of cocaine seeking was prevented by LHb inactivation or nonselective antagonism of LHb mAChRs. Here, we investigate mAChR subtypes mediating the effects of endogenous acetylcholine in this model of impulsive drug seeking and define cellular mechanisms in which mAChRs alter LHb neuron activity. Using in vitro electrophysiology, we find that LHb neurons are depolarized or hyperpolarized by the cholinergic agonists oxotremorine-M (Oxo-M) and carbachol (CCh), and that mAChRs inhibit synaptic GABA and glutamatergic inputs to these cells similarly in male and female rats. Synaptic effects of CCh were blocked by the M2-mAChR (M2R) antagonist AFDX-116 and not by pirenzepine, an M1-mAChR (M1R) antagonist. Oxo-M-mediated depolarizing currents were also blocked by AFDX-116. Although M2R activation inhibited excitatory and inhibitory inputs to LHb neurons, the effect on excitation was greater, suggesting a shift in excitatory-inhibitory balance toward net inhibition. Activation of VTA inhibitory inputs to LHb neurons, via channelrhodopsin-2 expression, evoked IPSCs that were inhibited by M2Rs. Finally, we measured LHb-dependent operant response inhibition for cocaine and found it impaired by antagonism of M2Rs, and not M1Rs. In summary, we show that a cholinergic signal to LHb and activation of M2Rs are critical to enable inhibition of responding for cocaine, and we define cellular mechanisms through which this may occur.SIGNIFICANCE STATEMENT The lateral habenula (LHb) is a brain region receiving information from brain areas involved in decision-making, and its output influences motivation, reward, and movement. This interface between thoughts, emotions, and actions is how the LHb permits adaptive behavior, and LHb dysfunction is implicated in psychiatric and drug use disorders. Silencing the LHb impairs control over cocaine seeking in rats, and mAChRs are also implicated. Here, we measured cocaine seeking while blocking different mAChRs and examined mechanisms of mAChR effects on LHb neurons. M2-mAChRs were necessary for control of cocaine seeking, and these receptors altered LHb neuron activity in several ways. Our study reveals that LHb M2-mAChRs represent a potential target for treating substance use disorders.
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Affiliation(s)
- Clara I C Wolfe
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program Computational and Systems Neuroscience Branch, Electrophysiology Research Section, Baltimore, MD 21224
| | - Eun-Kyung Hwang
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program Computational and Systems Neuroscience Branch, Electrophysiology Research Section, Baltimore, MD 21224
| | - Elfrieda C Ijomor
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program Computational and Systems Neuroscience Branch, Electrophysiology Research Section, Baltimore, MD 21224
| | - Agustin Zapata
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program Computational and Systems Neuroscience Branch, Electrophysiology Research Section, Baltimore, MD 21224
| | - Alexander F Hoffman
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program Computational and Systems Neuroscience Branch, Electrophysiology Research Section, Baltimore, MD 21224
| | - Carl R Lupica
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program Computational and Systems Neuroscience Branch, Electrophysiology Research Section, Baltimore, MD 21224
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6
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Jadhav KS, Bernheim AP, Aeschlimann L, Kirschmann G, Decosterd I, Hoffman AF, Lupica CR, Boutrel B. Reversing anterior insular cortex neuronal hypoexcitability attenuates compulsive behavior in adolescent rats. Proc Natl Acad Sci U S A 2022; 119:e2121247119. [PMID: 35584117 PMCID: PMC9173752 DOI: 10.1073/pnas.2121247119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 03/29/2022] [Indexed: 11/18/2022] Open
Abstract
Development of self-regulatory competencies during adolescence is partially dependent on normative brain maturation. Here, we report that adolescent rats as compared to adults exhibit impulsive and compulsive-like behavioral traits, the latter being associated with lower expression of mRNA levels of the immediate early gene zif268 in the anterior insula cortex (AIC). This suggests that underdeveloped AIC function in adolescent rats could contribute to an immature pattern of interoceptive cue integration in decision making and a compulsive phenotype. In support of this, we report that layer 5 pyramidal neurons in the adolescent rat AIC are hypoexcitable and receive fewer glutamatergic synaptic inputs compared to adults. Chemogenetic activation of the AIC attenuated compulsive traits in adolescent rats supporting the idea that in early stages of AIC maturity there exists a suboptimal integration of sensory and cognitive information that contributes to inflexible behaviors in specific conditions of reward availability.
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Affiliation(s)
- Kshitij S. Jadhav
- Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital and University of Lausanne, CH-1008 Lausanne, Switzerland
| | - Aurélien P. Bernheim
- Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital and University of Lausanne, CH-1008 Lausanne, Switzerland
| | - Léa Aeschlimann
- Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital and University of Lausanne, CH-1008 Lausanne, Switzerland
| | - Guylène Kirschmann
- Pain Center, Department of Anesthesiology, Lausanne University Hospital (CHUV) and Faculty of Biology and Medicine (FBM), University of Lausanne, CH-1011 Lausanne, Switzerland
| | - Isabelle Decosterd
- Pain Center, Department of Anesthesiology, Lausanne University Hospital (CHUV) and Faculty of Biology and Medicine (FBM), University of Lausanne, CH-1011 Lausanne, Switzerland
| | - Alexander F. Hoffman
- Electrophysiology Research Section, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, MD 21224
| | - Carl R. Lupica
- Electrophysiology Research Section, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, MD 21224
| | - Benjamin Boutrel
- Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital and University of Lausanne, CH-1008 Lausanne, Switzerland
- Division of Child and Adolescent Psychiatry, Department of Psychiatry, Lausanne University Hospital and University of Lausanne, CH-1004 Lausanne, Switzerland
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Hoffman AF, Hwang EK, Lupica CR. Impairment of Synaptic Plasticity by Cannabis, Δ 9-THC, and Synthetic Cannabinoids. Cold Spring Harb Perspect Med 2021; 11:cshperspect.a039743. [PMID: 32341064 PMCID: PMC8091957 DOI: 10.1101/cshperspect.a039743] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The ability of neurons to dynamically and flexibly encode synaptic inputs via short- and long-term plasticity is critical to an organism's ability to learn and adapt to the environment. Whereas synaptic plasticity may be encoded by pre- or postsynaptic mechanisms, current evidence suggests that optimization of learning requires both forms of plasticity. Endogenous cannabinoids (eCBs) play critical roles in modulating synaptic transmission via activation of cannabinoid CB1 receptors (CB1Rs) in many central nervous system (CNS) regions, and the eCB system has been implicated, either directly or indirectly, in several forms of synaptic plasticity. Because of this, perturbations within the eCB signaling system can lead to impairments in a variety of learned behaviors. One agent of altered eCB signaling is exposure to "exogenous cannabinoids" such as the primary psychoactive constituent of cannabis, Δ9-THC, or illicit synthetic cannabinoids that in many cases have higher potency and efficacy than Δ9-THC. Thus, by targeting the eCB system, these agonists can produce widespread impairment of synaptic plasticity by disrupting ongoing eCB function. Here, we review studies in which Δ9-THC and synthetic cannabinoids impair synaptic plasticity in a variety of neuronal circuits and examine evidence that this contributes to their well-documented ability to disrupt cognition and behavior.
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Affiliation(s)
- Alexander F Hoffman
- Electrophysiology Research Section, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA
| | - Eun-Kyung Hwang
- Electrophysiology Research Section, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA
| | - Carl R Lupica
- Electrophysiology Research Section, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA
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Hoffman AF, Hwang EK, Lupica CR. Erratum: Impairment of Synaptic Plasticity by Cannabis, Δ 9-THC, and Synthetic Cannabinoids. Cold Spring Harb Perspect Med 2020; 10:10/6/a040428. [PMID: 32482847 DOI: 10.1101/cshperspect.a040428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Yano H, Adhikari P, Naing S, Hoffman AF, Baumann MH, Lupica CR, Shi L. Positive Allosteric Modulation of the 5-HT 1A Receptor by Indole-Based Synthetic Cannabinoids Abused by Humans. ACS Chem Neurosci 2020; 11:1400-1405. [PMID: 32324370 DOI: 10.1021/acschemneuro.0c00034] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The nonmedical (i.e., recreational) misuse of synthetic cannabinoids (SCs) is a worldwide public health problem. When compared to cannabis, the misuse of SCs is associated with a higher incidence of serious adverse effects, suggesting the possible involvement of noncannabinoid sites of action. Here, we find that, unlike the phytocannabinoid Δ9-tetrahydrocannabinol, the indole-moiety containing SCs, AM2201 and JWH-018, act as positive allosteric modulators (PAMs) at the 5-HT1A receptor (5-HT1AR). This suggests that some biological effects of SCs might involve allosteric interactions with 5-HT1ARs. To test this hypothesis, we examined effects of AM2201 on 5-HT1AR agonist-activated G protein-coupled inwardly rectifying potassium channel currents in neurons in vitro and on the hypothermic response to 5-HT1AR stimulation in mice lacking the cannabinoid receptor 1. We found that both 5-HT1AR effects were potentiated by AM2201, suggesting that PAM activity at 5-HT1AR may represent a novel noncannabinoid receptor mechanism underlying the complex profile of effects for certain SCs.
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Lecca D, Bader M, Tweedie D, Hoffman AF, Jung YJ, Hsueh SC, Hoffer BJ, Becker RE, Pick CG, Lupica CR, Greig NH. (-)-Phenserine and the prevention of pre-programmed cell death and neuroinflammation in mild traumatic brain injury and Alzheimer's disease challenged mice. Neurobiol Dis 2019; 130:104528. [PMID: 31295555 PMCID: PMC6716152 DOI: 10.1016/j.nbd.2019.104528] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/05/2019] [Accepted: 07/06/2019] [Indexed: 01/12/2023] Open
Abstract
Mild traumatic brain injury (mTBI) is a risk factor for neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease (PD). TBI-derived neuropathologies are promoted by inflammatory processes: chronic microgliosis and release of pro-inflammatory cytokines that further promote neuronal dysfunction and loss. Herein, we evaluated the effect on pre-programmed cell death/neuroinflammation/synaptic integrity and function of (-)-Phenserine tartrate (Phen), an agent originally developed for AD. This was studied at two clinically translatable doses (2.5 and 5.0 mg/kg, BID), in a weight drop (concussive) mTBI model in wild type (WT) and AD APP/PSEN1 transgenic mice. Phen mitigated mTBI-induced cognitive impairment, assessed by Novel Object Recognition and Y-maze behavioral paradigms, in WT mice. Phen fully abated mTBI-induced neurodegeneration, evaluated by counting Fluoro-Jade C-positive (FJC+) cells, in hippocampus and cortex of WT mice. In APP/PSEN1 mice, degenerating cell counts were consistently greater across all experimental groups vs. WT mice. mTBI elevated FJC+ cell counts vs. the APP/PSEN1 control (sham) group, and Phen similarly mitigated this. Anti-inflammatory effects on microglial activation (IBA1-immunoreactivity (IR)) and the pro-inflammatory cytokine TNF-α were evaluated. mTBI increased IBA1-IR and TNF-α/IBA1 colocalization vs. sham, both in WT and APP/PSEN1 mice. Phen decreased IBA1-IR throughout hippocampi and cortices of WT mice, and in cortices of AD mice. Phen, likewise, reduced levels of IBA1/TNF-α-IR colocalization volume across all areas in WT animals, with a similar trend in APP/PSEN1 mice. Actions on astrocyte activation by mTBI were followed by evaluating GFAP, and were similarly mitigated by Phen. Synaptic density was evaluated by quantifying PSD-95+ dendritic spines and Synaptophysin (Syn)-IR. Both were significantly reduced in mTBI vs. sham in both WT and APP/PSEN1 mice. Phen fully reversed the PSD-95+ spine loss in WT and Syn-IR decrease in both WT and APP/PSEN1 mice. To associate immunohistochemical changes in synaptic markers with function, hippocampal long term potentiation (LTP) was induced in WT mice. LTP was impaired by mTBI, and this impairment was mitigated by Phen. In synopsis, clinically translatable doses of Phen ameliorated mTBI-mediated pre-programmed cell death/neuroinflammation/synaptic dysfunction in WT mice, consistent with fully mitigating mTBI-induced cognitive impairments. Phen additionally demonstrated positive actions in the more pathologic brain microenvironment of AD mice, further supporting consideration of its repurposing as a treatment for mTBI.
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Affiliation(s)
- Daniela Lecca
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Miaad Bader
- Department of Anatomy and Anthropology, Sackler School of Medicine, Tel-Aviv University, Tel Aviv 69978, Israel
| | - David Tweedie
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Alexander F Hoffman
- Electrophysiology Research Section, Cellular Neurobiology Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, 21224 Baltimore, MD, USA
| | - Yoo Jin Jung
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Shin-Chang Hsueh
- Department of Neurosurgery, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Barry J Hoffer
- Department of Neurosurgery, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Robert E Becker
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD 21224, USA; Aristea Translational Medicine Corporation, Park City, UT 84098, USA
| | - Chaim G Pick
- Department of Anatomy and Anthropology, Sackler School of Medicine, Tel-Aviv University, Tel Aviv 69978, Israel; Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv 69978, Israel; Center for the Biology of Addictive Diseases, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Carl R Lupica
- Electrophysiology Research Section, Cellular Neurobiology Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, 21224 Baltimore, MD, USA
| | - Nigel H Greig
- Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD 21224, USA.
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Lecca D, Bader M, Tweedie D, Lahiri DK, Becker RE, Pick C, Hoffman AF, Lupica CR, Greig NH. P3-056: PROTECTIVE EFFECTS OF (-)-PHENSERINE (PHEN) IN ALZHEIMER'S DISEASE (AD) AND MILD TRAUMATIC BRAIN INJURY (MTBI) MURINE MODELS. Alzheimers Dement 2019. [DOI: 10.1016/j.jalz.2019.06.3083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
| | | | | | - Debomoy K. Lahiri
- Department of Psychiatry; Indiana University School of Medicine; Indianapolis IN USA
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12
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Bäck S, Necarsulmer J, Whitaker LR, Coke LM, Koivula P, Heathward EJ, Fortuno LV, Zhang Y, Yeh CG, Baldwin HA, Spencer MD, Mejias-Aponte CA, Pickel J, Hoffman AF, Spivak CE, Lupica CR, Underhill SM, Amara SG, Domanskyi A, Anttila JE, Airavaara M, Hope BT, Hamra FK, Richie CT, Harvey BK. Neuron-Specific Genome Modification in the Adult Rat Brain Using CRISPR-Cas9 Transgenic Rats. Neuron 2019; 102:105-119.e8. [PMID: 30792150 DOI: 10.1016/j.neuron.2019.01.035] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 12/13/2018] [Accepted: 01/16/2019] [Indexed: 12/28/2022]
Abstract
Historically, the rat has been the preferred animal model for behavioral studies. Limitations in genome modification have, however, caused a lag in their use compared to the bevy of available transgenic mice. Here, we have developed several transgenic tools, including viral vectors and transgenic rats, for targeted genome modification in specific adult rat neurons using CRISPR-Cas9 technology. Starting from wild-type rats, knockout of tyrosine hydroxylase was achieved with adeno-associated viral (AAV) vectors expressing Cas9 or guide RNAs (gRNAs). We subsequently created an AAV vector for Cre-dependent gRNA expression as well as three new transgenic rat lines to specifically target CRISPR-Cas9 components to dopaminergic neurons. One rat represents the first knockin rat model made by germline gene targeting in spermatogonial stem cells. The rats described herein serve as a versatile platform for making cell-specific and sequence-specific genome modifications in the adult brain and potentially other Cre-expressing tissues of the rat.
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Affiliation(s)
- Susanne Bäck
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Julie Necarsulmer
- Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Leslie R Whitaker
- Neuronal Ensembles in Drug Addiction Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Lamarque M Coke
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Pyry Koivula
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Emily J Heathward
- Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Lowella V Fortuno
- Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Yajun Zhang
- Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - C Grace Yeh
- Neuronal Ensembles in Drug Addiction Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Heather A Baldwin
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Morgan D Spencer
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Carlos A Mejias-Aponte
- Histology Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - James Pickel
- Transgenic Technology Core, Intramural Research Program, National Institute of Mental Health, Bethesda, MD 20892, USA
| | - Alexander F Hoffman
- Electrophysiology Research Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Charles E Spivak
- Electrophysiology Research Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Carl R Lupica
- Electrophysiology Research Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Suzanne M Underhill
- Laboratory of Molecular and Cellular Neurobiology, Intramural Research Program, National Institute of Mental Health, Bethesda, MD 20892, USA
| | - Susan G Amara
- Laboratory of Molecular and Cellular Neurobiology, Intramural Research Program, National Institute of Mental Health, Bethesda, MD 20892, USA
| | - Andrii Domanskyi
- Institute of Biotechnology, HiLIFE, University of Helsinki, 00014 Helsinki, Finland
| | - Jenni E Anttila
- Institute of Biotechnology, HiLIFE, University of Helsinki, 00014 Helsinki, Finland
| | - Mikko Airavaara
- Institute of Biotechnology, HiLIFE, University of Helsinki, 00014 Helsinki, Finland
| | - Bruce T Hope
- Neuronal Ensembles in Drug Addiction Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - F Kent Hamra
- Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Christopher T Richie
- Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
| | - Brandon K Harvey
- Molecular Mechanisms of Cellular Stress and Inflammation Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA; Optogenetics and Transgenic Technology Core/Genetic Engineering and Viral Vector Core, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA.
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13
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Yano H, Bonifazi A, Hoffman AF, Lupica CR, Shi LR, Newman AH. Novel sumanirole bivalent analogues as potent dopamine D2 receptor Go‐protein biased agonists. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.667.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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14
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Bonifazi A, Yano H, Guerrero AM, Kumar V, Hoffman AF, Lupica CR, Shi L, Newman AH. Novel and Potent Dopamine D 2 Receptor Go-Protein Biased Agonists. ACS Pharmacol Transl Sci 2019; 2:52-65. [PMID: 30775693 PMCID: PMC6371206 DOI: 10.1021/acsptsci.8b00060] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Indexed: 12/18/2022]
Abstract
![]()
The
discovery of functionally biased and physiologically beneficial
ligands directed toward G-protein coupled receptors (GPCRs) has provided
the impetus to design dopamine D2 receptor (D2R) targeted molecules that may be therapeutically advantageous for
the treatment of certain neuropsychiatric or basal ganglia related
disorders. Here we describe the synthesis of a novel series of D2R agonists linking the D2R unbiased agonist sumanirole
with privileged secondary molecular fragments. The resulting ligands
demonstrate improved D2R affinity and selectivity over
sumanirole. Extensive in vitro functional studies
and bias factor analysis led to the identification of a novel class
of highly potent Go-protein biased full D2R agonists with
more than 10-fold and 1000-fold bias selectivity toward activation
of specific G-protein subtypes and β-arrestin, respectively.
Intracellular electrophysiological recordings from midbrain dopamine
neurons demonstrated that Go-protein selective agonists can elicit
prolonged ligand-induced GIRK activity via D2Rs, which
may be beneficial in the treatment of dyskinesias associated with
dopamine system dysfunction.
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Affiliation(s)
- Alessandro Bonifazi
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224, United States
| | - Hideaki Yano
- Computational Chemistry and Molecular Biophysics Unit, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224, United States
| | - Adrian M Guerrero
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224, United States
| | - Vivek Kumar
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224, United States
| | - Alexander F Hoffman
- Electrophysiology Research Section, Cellular Neurobiology Research Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224, United States
| | - Carl R Lupica
- Electrophysiology Research Section, Cellular Neurobiology Research Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224, United States
| | - Lei Shi
- Computational Chemistry and Molecular Biophysics Unit, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224, United States
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, National Institute on Drug Abuse - Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, Maryland 21224, United States
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15
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Lupica CR, Hoffman AF. Cannabinoid disruption of learning mechanisms involved in reward processing. ACTA ACUST UNITED AC 2018; 25:435-445. [PMID: 30115765 PMCID: PMC6097761 DOI: 10.1101/lm.046748.117] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 07/06/2018] [Indexed: 02/06/2023]
Abstract
The increasing use of cannabis, its derivatives, and synthetic cannabinoids for medicinal and recreational purposes has led to burgeoning interest in understanding the addictive potential of this class of molecules. It is estimated that ∼10% of marijuana users will eventually show signs of dependence on the drug, and the diagnosis of cannabis use disorder (CUD) is increasing in the United States. The molecule that sustains the use of cannabis is Δ9-tetrahydrocannabinol (Δ9-THC), and our knowledge of its effects, and those of other cannabinoids on brain function has expanded rapidly in the past two decades. Additionally, the identification of endogenous cannabinoid (endocannabinoid) systems in brain and their roles in physiology and behavior, demonstrate extensive involvement of these lipid signaling molecules in regulating CNS function. Here, we examine roles for endogenous cannabinoids in shaping synaptic activity in cortical and subcortical brain circuits, and we discuss mechanisms in which exogenous cannabinoids, such as Δ9-THC, interact with endocannabinoid systems to disrupt neuronal network oscillations. We then explore how perturbation of the interaction of this activity within brain reward circuits may lead to impaired learning. Finally, we propose that disruption of cellular plasticity mechanisms by exogenous cannabinoids in cortical and subcortical circuits may explain the difficulty in establishing viable cannabinoid self-administration models in animals.
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Affiliation(s)
- Carl R Lupica
- Electrophysiology Research Section, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA
| | - Alexander F Hoffman
- Electrophysiology Research Section, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA
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16
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Wright AM, Zapata A, Baumann MH, Elmore JS, Hoffman AF, Lupica CR. Enduring Loss of Serotonergic Control of Orbitofrontal Cortex Function Following Contingent and Noncontingent Cocaine Exposure. Cereb Cortex 2018; 27:5463-5476. [PMID: 27733540 DOI: 10.1093/cercor/bhw312] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 09/19/2016] [Indexed: 12/13/2022] Open
Abstract
Clinical descriptions of cocaine addiction include compulsive drug seeking and maladaptive decision-making despite substantial aversive consequences. Research suggests that this may result from altered orbitofrontal cortex (OFC) function and its participation in outcome-based behavior. Clinical and animal studies also implicate serotonin in the regulation of OFC function in addiction and other neuropsychiatric disorders. Here we test the hypothesis that exposure to cocaine, through self-administration (CSA) or yoked-administration (CYA), alters the regulation of OFC function by 5-HT. Using whole-cell electrophysiology in brain slices from naïve rats we find that 5-HT1A receptors generate hyperpolarizing outward currents in layer-V OFC pyramidal neurons, and that 5-HT2A receptors increase glutamate release onto these cells. Following extended withdrawal from CSA or CYA, this 5-HT regulation of OFC activity is largely lost. In-situ hybridization of 5-HT receptor transcripts reveals that 5-HT1A receptor mRNA is unaffected and 5-HT2A receptor mRNA is significantly elevated after CSA or CYA. These results demonstrate that 5-HT control of OFC neurons is disrupted for extended periods following cocaine exposure. We hypothesize that this dysregulation of 5-HT signaling leads to enduring disruptions of OFC network activity that this is involved in impaired decision-making associated with cocaine addiction.
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Affiliation(s)
- Andrew M Wright
- Electrophysiology Research Section, Cellular Neurobiology Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Agustin Zapata
- Electrophysiology Research Section, Cellular Neurobiology Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Michael H Baumann
- Designer Drug Research Unit, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Joshua S Elmore
- Designer Drug Research Unit, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Alexander F Hoffman
- Electrophysiology Research Section, Cellular Neurobiology Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Carl R Lupica
- Electrophysiology Research Section, Cellular Neurobiology Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
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17
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Lupica CR, Hu Y, Devinsky O, Hoffman AF. Cannabinoids as hippocampal network administrators. Neuropharmacology 2017; 124:25-37. [PMID: 28392266 DOI: 10.1016/j.neuropharm.2017.04.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 04/03/2017] [Accepted: 04/04/2017] [Indexed: 12/30/2022]
Abstract
Extensive pioneering studies performed in the hippocampus have greatly contributed to our knowledge of an endogenous cannabinoid system comprised of the molecular machinery necessary to process endocannabinoid lipid messengers and their associated cannabinoid receptors. Moreover, a foundation of knowledge regarding the function of hippocampal circuits, and its role in supporting synaptic plasticity has facilitated our understanding of the roles cannabinoids play in the diverse behaviors in which the hippocampus participates, in both normal and pathological states. In this review, we present an historical overview of research pertaining to the hippocampal cannabinoid system to provide context in which to understand the participation of the hippocampus in cognition, behavior, and epilepsy. We also examine potential roles for the hippocampal formation in mediating dysfunctional behavior, and assert that these phenomena reflect disordered physiological activity within the hippocampus and its interactions with other brain regions after exposure to synthetic cannabinoids, and the phytocannabinoids found in marijuana, such as Δ9-THC and cannabidiol. In this regard, we examine contemporary hypotheses concerning the hippocampal endocannabinoid system's participation in psychotic disorders, schizophrenia, and epilepsy, and examine cannabinoid-sensitive cellular mechanisms contributing to coherent network oscillations as potential contributors to these disorders. This article is part of the Special Issue entitled "A New Dawn in Cannabinoid Neurobiology".
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Affiliation(s)
- Carl R Lupica
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program, Electrophysiology Research Section, Baltimore, MD, USA.
| | - Yuhan Hu
- School of Chemistry, Food and Nutritional Sciences and Pharmacy, University of Reading, Reading, UK
| | | | - Alexander F Hoffman
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program, Electrophysiology Research Section, Baltimore, MD, USA
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18
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Hoffman AF, Lycas MD, Kaczmarzyk JR, Spivak CE, Baumann MH, Lupica CR. Disruption of hippocampal synaptic transmission and long-term potentiation by psychoactive synthetic cannabinoid 'Spice' compounds: comparison with Δ 9 -tetrahydrocannabinol. Addict Biol 2017; 22:390-399. [PMID: 26732435 PMCID: PMC4935655 DOI: 10.1111/adb.12334] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 10/16/2015] [Accepted: 10/21/2015] [Indexed: 12/16/2022]
Abstract
There has been a marked increase in the availability of synthetic drugs designed to mimic the effects of marijuana. These cannabimimetic drugs, sold illicitly as 'Spice' and related products, are associated with serious medical complications in some users. In vitro studies suggest that synthetic cannabinoids in these preparations are potent agonists at central cannabinoid CB1 receptors (CB1Rs), but few investigations have delineated their cellular effects, particularly in comparison with the psychoactive component of marijuana, Δ9 -tetrahydrocannabinol (Δ9 -THC). We compared the ability of three widely abused synthetic cannabinoids and Δ9 -THC to alter glutamate release and long-term potentiation in the mouse hippocampus. JWH-018 was the most potent inhibitor of hippocampal synaptic transmission (EC50 ~15 nM), whereas its fluoropentyl derivative, AM2201, inhibited synaptic transmission with slightly lower potency (EC50 ~60 nM). The newer synthetic cannabinoid, XLR-11, displayed much lower potency (EC50 ~900 nM) that was similar to Δ9 -THC (EC50 ~700 nM). The effects of all compounds occurred via activation of CB1Rs, as demonstrated by reversal with the selective antagonist/inverse agonist AM251 or the neutral CB1R antagonist PIMSR1. Moreover, AM2201 was without effect in the hippocampus of transgenic mice lacking the CB1R. Hippocampal slices exposed to either synthetic cannabinoids or Δ9 -THC exhibited significantly impaired long-term potentiation (LTP). We find that, compared with Δ9 -THC, the first-generation cannabinoids found in Spice preparations display higher potency, whereas a recent synthetic cannabinoid is roughly equipotent with Δ9 -THC. The disruption of synaptic function by these synthetic cannabinoids is likely to lead to profound impairments in cognitive and behavioral function.
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Affiliation(s)
- Alexander F. Hoffman
- Electrophysiology Research Section, Cellular Neurobiology BranchNational Institute on Drug Abuse Intramural Research ProgramBaltimoreMDUSA
| | - Matthew D. Lycas
- Electrophysiology Research Section, Cellular Neurobiology BranchNational Institute on Drug Abuse Intramural Research ProgramBaltimoreMDUSA
| | - Jakub R. Kaczmarzyk
- Electrophysiology Research Section, Cellular Neurobiology BranchNational Institute on Drug Abuse Intramural Research ProgramBaltimoreMDUSA
| | - Charles E. Spivak
- Electrophysiology Research Section, Cellular Neurobiology BranchNational Institute on Drug Abuse Intramural Research ProgramBaltimoreMDUSA
| | - Michael H. Baumann
- Designer Drug Research UnitNational Institute on Drug Abuse Intramural Research ProgramBaltimoreMDUSA
| | - Carl R. Lupica
- Electrophysiology Research Section, Cellular Neurobiology BranchNational Institute on Drug Abuse Intramural Research ProgramBaltimoreMDUSA
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19
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Hoffman AF, Spivak CE, Lupica CR. Enhanced Dopamine Release by Dopamine Transport Inhibitors Described by a Restricted Diffusion Model and Fast-Scan Cyclic Voltammetry. ACS Chem Neurosci 2016; 7:700-9. [PMID: 27018734 DOI: 10.1021/acschemneuro.5b00277] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Fast-scan cyclic voltammetry (FSCV) using carbon fiber electrodes is widely used to rapidly monitor changes in dopamine (DA) levels in vitro and in vivo. Current analytical approaches utilize parameters such as peak oxidation current amplitude and decay times to estimate release and uptake processes, respectively. However, peak amplitude changes are often observed with uptake inhibitors, thereby confounding the interpretation of these parameters. To overcome this limitation, we demonstrate that a simple five-parameter, two-compartment model mathematically describes DA signals as a balance of release (r/ke) and uptake (ku), summed with adsorption (kads and kdes) of DA to the carbon electrode surface. Using nonlinear regression, we demonstrate that our model precisely describes measured DA signals obtained in brain slice recordings. The parameters extracted from these curves were then validated using pharmacological manipulations that selectively alter vesicular release or DA transporter (DAT)-mediated uptake. Manipulation of DA release through altering the Ca(2+)/Mg(2+) ratio or adding tetrodotoxin reduced the release parameter with no effect on the uptake parameter. DAT inhibitors methylenedioxypyrovalerone, cocaine, and nomifensine significantly reduced uptake and increased vesicular DA release. In contrast, a low concentration of amphetamine reduced uptake but had no effect on DA release. Finally, the kappa opioid receptor agonist U50,488 significantly reduced vesicular DA release but had no effect on uptake. Together, these data demonstrate a novel analytical approach to distinguish the effects of manipulations on DA release or uptake that can be used to interpret FSCV data.
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Affiliation(s)
- Alexander F. Hoffman
- Electrophysiology Research
Section, Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, Baltimore, Maryland 21224, United States
| | - Charles E. Spivak
- Electrophysiology Research
Section, Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, Baltimore, Maryland 21224, United States
| | - Carl R. Lupica
- Electrophysiology Research
Section, Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, Baltimore, Maryland 21224, United States
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Zhang S, Qi J, Li X, Wang HL, Britt JP, Hoffman AF, Bonci A, Lupica CR, Morales M. Dopaminergic and glutamatergic microdomains in a subset of rodent mesoaccumbens axons. Nat Neurosci 2015; 18:386-92. [PMID: 25664911 PMCID: PMC4340758 DOI: 10.1038/nn.3945] [Citation(s) in RCA: 174] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/13/2015] [Indexed: 12/14/2022]
Abstract
Mesoaccumbens fibers are thought to co-release dopamine and glutamate. However, the mechanism is unclear, and co-release by mesoaccumbens fibers has not been documented. Using electron microcopy, we found that some mesoaccumbens fibers have vesicular transporters for dopamine (VMAT2) in axon segments that are continuous with axon terminals that lack VMAT2, but contain vesicular glutamate transporters type 2 (VGluT2). In vivo overexpression of VMAT2 did not change the segregation of the two vesicular types, suggesting the existence of highly regulated mechanisms for maintaining this segregation. The mesoaccumbens axon terminals containing VGluT2 vesicles make asymmetric synapses, commonly associated with excitatory signaling. Using optogenetics, we found that dopamine and glutamate were released from the same mesoaccumbens fibers. These findings reveal a complex type of signaling by mesoaccumbens fibers in which dopamine and glutamate can be released from the same axons, but are not normally released at the same site or from the same synaptic vesicles.
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Affiliation(s)
- Shiliang Zhang
- National Institute on Drug Abuse, Neuronal Networks Section, US National Institutes of Health, Baltimore, Maryland, USA
| | - Jia Qi
- National Institute on Drug Abuse, Neuronal Networks Section, US National Institutes of Health, Baltimore, Maryland, USA
| | - Xueping Li
- National Institute on Drug Abuse, Neuronal Networks Section, US National Institutes of Health, Baltimore, Maryland, USA
| | - Hui-Ling Wang
- National Institute on Drug Abuse, Neuronal Networks Section, US National Institutes of Health, Baltimore, Maryland, USA
| | - Jonathan P. Britt
- National Institute on Drug Abuse, Synaptic Plasticity Section, US National Institutes of Health, Baltimore, Maryland, USA
| | - Alexander F. Hoffman
- National Institute on Drug Abuse, Electrophysiology Research Section, US National Institutes of Health, Baltimore, Maryland, USA
| | - Antonello Bonci
- National Institute on Drug Abuse, Synaptic Plasticity Section, US National Institutes of Health, Baltimore, Maryland, USA
| | - Carl R. Lupica
- National Institute on Drug Abuse, Electrophysiology Research Section, US National Institutes of Health, Baltimore, Maryland, USA
| | - Marisela Morales
- National Institute on Drug Abuse, Neuronal Networks Section, US National Institutes of Health, Baltimore, Maryland, USA
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21
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Qi J, Zhang S, Wang HL, Wang H, de Jesus Aceves Buendia J, Hoffman AF, Lupica CR, Seal RP, Morales M. A glutamatergic reward input from the dorsal raphe to ventral tegmental area dopamine neurons. Nat Commun 2014; 5:5390. [PMID: 25388237 PMCID: PMC4231541 DOI: 10.1038/ncomms6390] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 09/26/2014] [Indexed: 02/07/2023] Open
Abstract
Electrical stimulation of the dorsal raphe (DR) and ventral tegmental area (VTA) activates the fibres of the same reward pathway but the phenotype of this pathway and the direction of the reward-relevant fibres have not been determined. Here we report rewarding effects following activation of a DR-originating pathway consisting of vesicular glutamate transporter 3 (VGluT3) containing neurons that form asymmetric synapses onto VTA dopamine neurons that project to nucleus accumbens. Optogenetic VTA activation of this projection elicits AMPA-mediated synaptic excitatory currents in VTA mesoaccumbens dopaminergic neurons and causes dopamine release in nucleus accumbens. Activation also reinforces instrumental behaviour and establishes conditioned place preferences. These findings indicate that the DR-VGluT3 pathway to VTA utilizes glutamate as a neurotransmitter and is a substrate linking the DR-one of the most sensitive reward sites in the brain--to VTA dopaminergic neurons.
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Affiliation(s)
- Jia Qi
- National Institute on Drug Abuse, Neuronal Networks Section, National Institutes of Health, Baltimore, Maryland, USA
| | - Shiliang Zhang
- National Institute on Drug Abuse, Neuronal Networks Section, National Institutes of Health, Baltimore, Maryland, USA
| | - Hui-Ling Wang
- National Institute on Drug Abuse, Neuronal Networks Section, National Institutes of Health, Baltimore, Maryland, USA
| | - Huikun Wang
- National Institute on Drug Abuse, Electrophysiology Research Section, National Institutes of Health, Baltimore, Maryland, USA
| | - Jose de Jesus Aceves Buendia
- National Institute on Drug Abuse, Neuronal Networks Section, National Institutes of Health, Baltimore, Maryland, USA
| | - Alexander F. Hoffman
- National Institute on Drug Abuse, Electrophysiology Research Section, National Institutes of Health, Baltimore, Maryland, USA
| | - Carl R. Lupica
- National Institute on Drug Abuse, Electrophysiology Research Section, National Institutes of Health, Baltimore, Maryland, USA
| | - Rebecca P. Seal
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Marisela Morales
- National Institute on Drug Abuse, Neuronal Networks Section, National Institutes of Health, Baltimore, Maryland, USA
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Good CH, Wang H, Chen YH, Mejias-Aponte CA, Hoffman AF, Lupica CR. Dopamine D4 receptor excitation of lateral habenula neurons via multiple cellular mechanisms. J Neurosci 2013; 33:16853-64. [PMID: 24155292 PMCID: PMC3807019 DOI: 10.1523/jneurosci.1844-13.2013] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 08/15/2013] [Accepted: 09/05/2013] [Indexed: 12/31/2022] Open
Abstract
Glutamatergic lateral habenula (LHb) output communicates negative motivational valence to ventral tegmental area (VTA) dopamine (DA) neurons via activation of the rostromedial tegmental nucleus (RMTg). However, the LHb also receives a poorly understood DA input from the VTA, which we hypothesized constitutes an important feedback loop regulating DA responses to stimuli. Using whole-cell electrophysiology in rat brain slices, we find that DA initiates a depolarizing inward current (I(DAi)) and increases spontaneous firing in 32% of LHb neurons. I(DAi) was also observed upon application of amphetamine or the DA uptake blockers cocaine or GBR12935, indicating involvement of endogenous DA. I(DAi) was blocked by D4 receptor (D4R) antagonists (L745,870 or L741,742), and mimicked by a selective D4R agonist (A412997). I(DAi) was associated with increased whole-cell conductance and was blocked by Cs+ or a selective blocker of hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channel, ZD7288. I(DAi) was also associated with a depolarizing shift in half-activation voltage for the hyperpolarization-activated cation current (Ih) mediated by HCN channels. Recordings from LHb neurons containing fluorescent retrograde tracers revealed that I(DAi) was observed only in cells projecting to the RMTg and not the VTA. In parallel with direct depolarization, DA also strongly increased synaptic glutamate release and reduced synaptic GABA release onto LHb cells. These results demonstrate that DA can excite glutamatergic LHb output to RMTg via multiple cellular mechanisms. Since the RMTg strongly inhibits midbrain DA neurons, activation of LHb output to RMTg by DA represents a negative feedback loop that may dampen DA neuron output following activation.
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Affiliation(s)
- Cameron H. Good
- Cellular Neurobiology Research Branch
- Electrophysiology Research Section, and
| | - Huikun Wang
- Cellular Neurobiology Research Branch
- Electrophysiology Research Section, and
| | - Yuan-Hao Chen
- Department of Neurosurgery, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan, Republic of China
| | - Carlos A. Mejias-Aponte
- Integrative Neuroscience Research Branch, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, US Department of Health and Human Services, Baltimore, Maryland 21224, and
| | | | - Carl R. Lupica
- Cellular Neurobiology Research Branch
- Electrophysiology Research Section, and
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Abstract
The availability of potent synthetic agonists for cannabinoid receptors has facilitated our understanding of cannabinoid actions on synaptic transmission in the central nervous system. Moreover, the ability of these compounds to inhibit neurotransmitter release at many central synapses is thought to underlie most of the behavioral effects of cannabinoid agonists. However, despite the widespread use and misuse of marijuana, and recognition of its potential adverse psychological effects in humans, comparatively few studies have examined the actions of its primary psychoactive constituent, Δ(9)-tetrahydrocannabinol (THC), at well-defined synaptic pathways. Here we examine the recent literature describing the effects of acute and repeated THC exposure on synaptic function in several brain regions and explore the importance of these neurobiological actions of THC in drug addiction.
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Affiliation(s)
- Alexander F Hoffman
- U.S. Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse Intramural Research Program, Electrophysiology Research Section, Baltimore, Maryland 21224, USA
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Baumann MH, Partilla JS, Lehner KR, Thorndike EB, Hoffman AF, Holy M, Rothman RB, Goldberg SR, Lupica CR, Sitte HH, Brandt SD, Tella SR, Cozzi NV, Schindler CW. Powerful cocaine-like actions of 3,4-methylenedioxypyrovalerone (MDPV), a principal constituent of psychoactive 'bath salts' products. Neuropsychopharmacology 2013; 38:552-62. [PMID: 23072836 PMCID: PMC3572453 DOI: 10.1038/npp.2012.204] [Citation(s) in RCA: 316] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The abuse of psychoactive 'bath salts' containing cathinones such as 3,4-methylenedioxypyrovalerone (MDPV) is a growing public health concern, yet little is known about their pharmacology. Here, we evaluated the effects of MDPV and related drugs using molecular, cellular, and whole-animal methods. In vitro transporter assays were performed in rat brain synaptosomes and in cells expressing human transporters, while clearance of endogenous dopamine was measured by fast-scan cyclic voltammetry in mouse striatal slices. Assessments of in vivo neurochemistry, locomotor activity, and cardiovascular parameters were carried out in rats. We found that MDPV blocks uptake of [(3)H]dopamine (IC(50)=4.1 nM) and [(3)H]norepinephrine (IC(50)=26 nM) with high potency but has weak effects on uptake of [(3)H]serotonin (IC(50)=3349 nM). In contrast to other psychoactive cathinones (eg, mephedrone), MDPV is not a transporter substrate. The clearance of endogenous dopamine is inhibited by MDPV and cocaine in a similar manner, but MDPV displays greater potency and efficacy. Consistent with in vitro findings, MDPV (0.1-0.3 mg/kg, intravenous) increases extracellular concentrations of dopamine in the nucleus accumbens. Additionally, MDPV (0.1-3.0 mg/kg, subcutaneous) is at least 10 times more potent than cocaine at producing locomotor activation, tachycardia, and hypertension in rats. Our data show that MDPV is a monoamine transporter blocker with increased potency and selectivity for catecholamines when compared with cocaine. The robust stimulation of dopamine transmission by MDPV predicts serious potential for abuse and may provide a mechanism to explain the adverse effects observed in humans taking high doses of 'bath salts' preparations.
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Affiliation(s)
- Michael H Baumann
- Medicinal Chemistry Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA.
| | - John S Partilla
- Medicinal Chemistry Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Kurt R Lehner
- Medicinal Chemistry Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Eric B Thorndike
- Preclinical Pharmacology Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Alexander F Hoffman
- Electrophysiology Research Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Marion Holy
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Richard B Rothman
- Medicinal Chemistry Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Steven R Goldberg
- Preclinical Pharmacology Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Carl R Lupica
- Electrophysiology Research Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Harald H Sitte
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Simon D Brandt
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK
| | - Srihari R Tella
- Drug and Chemical Evaluation Section, Office of Diversion Control, Drug Enforcement Administration, Springfield, VA, USA
| | - Nicholas V Cozzi
- Neuropharmacology Laboratory, Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Charles W Schindler
- Preclinical Pharmacology Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
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25
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Zhang Y, Granholm AC, Huh K, Shan L, Diaz-Ruiz O, Malik N, Olson L, Hoffer BJ, Lupica CR, Hoffman AF, Bäckman CM. PTEN deletion enhances survival, neurite outgrowth and function of dopamine neuron grafts to MitoPark mice. Brain 2012; 135:2736-49. [PMID: 22961549 PMCID: PMC3437026 DOI: 10.1093/brain/aws196] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Clinical trials in Parkinson’s disease have shown that transplants of embryonic mesencephalic dopamine neurons form new functional connections within the host striatum, but the therapeutic benefits have been highly variable. One obstacle has been poor survival and integration of grafted dopamine neurons. Activation of Akt, a serine/threonine kinase that promotes cell survival and growth, increases the ability of neurons to survive after injury and to regenerate lost neuronal connections. Because the lipid phosphatase, phosphatase and tensin homolog (PTEN) inhibits Akt, we generated a mouse with conditional knock-out of PTEN in dopamine neurons, leading to constitutive expression of Akt in these neurons. Ventral mesencephalic tissue from dopamine phosphatase and tensin homologue knock-out or control animals was then transplanted bilaterally into the dopamine depleted striata of MitoPark mice that express a parkinsonian phenotype because of severe respiratory chain dysfunction in dopamine neurons. After transplantation into MitoPark mice, PTEN-deficient dopamine neurons were less susceptible to cell death, and exhibited a more extensive pattern of fibre outgrowth compared to control grafts. Voltammetric measurements demonstrated that dopamine release and reuptake were significantly increased in the striata of animals receiving dopamine PTEN knock-out transplants. These animals also displayed enhanced spontaneous and drug-induced locomotor activity, relative to control transplanted MitoPark mice. Our results suggest that disinhibition of the Akt-signalling pathway may provide a valuable strategy to enhance survival, function and integration of grafted dopamine neurons within the host striatum and, more generally, to improve survival and integration of different forms of neural grafts.
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Affiliation(s)
- YaJun Zhang
- Integrative Neuroscience Branch, National Institute on Drug Abuse Intramural Research Programme, National Institutes of Health, Baltimore, MD 21224, USA
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26
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Koya E, Cruz FC, Ator R, Golden SA, Hoffman AF, Lupica CR, Hope BT. Silent synapses in selectively activated nucleus accumbens neurons following cocaine sensitization. Nat Neurosci 2012; 15:1556-62. [PMID: 23023294 PMCID: PMC3483356 DOI: 10.1038/nn.3232] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 09/06/2012] [Indexed: 11/17/2022]
Abstract
Cocaine-induced alterations in synaptic glutamate function in nucleus accumbens are thought to mediate drug-related behaviors such as psychomotor sensitization. However, previous studies examined global alterations in randomly selected accumbens neurons regardless of their activation state during cocaine-induced behavior. We recently found that a minority of strongly activated Fos-expressing accumbens neurons are necessary for cocaine-induced psychomotor sensitization while the majority of accumbens neurons are less directly involved. Here, we assessed synaptic alterations in these strongly activated accumbens neurons in c-fos-GFP mice that express a fusion protein of Fos and green fluorescent protein (GFP) in strongly activated neurons and compared these alterations with those in surrounding non-activated neurons. Cocaine sensitization produced higher levels of ‘silent synapses’ that contained functional NMDA receptors and non-functional AMPA receptors in only GFP-positive neurons, 6–11 days after sensitization. Thus unique synaptic alterations are induced in the most strongly activated accumbens neurons that mediate psychomotor sensitization.
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Affiliation(s)
- Eisuke Koya
- Behavioral Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, US National Institutes of Health, Department of Health and Human Services, Baltimore, Maryland, USA
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Diaz-Ruiz O, Zhang Y, Shan L, Malik N, Hoffman AF, Ladenheim B, Cadet JL, Lupica CR, Tagliaferro A, Brusco A, Bäckman CM. Attenuated response to methamphetamine sensitization and deficits in motor learning and memory after selective deletion of β-catenin in dopamine neurons. Learn Mem 2012; 19:341-50. [PMID: 22822182 DOI: 10.1101/lm.026716.112] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In the present study, we analyzed mice with a targeted deletion of β-catenin in DA neurons (DA-βcat KO mice) to address the functional significance of this molecule in the shaping of synaptic responses associated with motor learning and following exposure to drugs of abuse. Relative to controls, DA-βcat KO mice showed significant deficits in their ability to form long-term memories and displayed reduced expression of methamphetamine-induced behavioral sensitization after subsequent challenge doses with this drug, suggesting that motor learning and drug-induced learning plasticity are altered in these mice. Morphological analyses showed no changes in the number or distribution of tyrosine hydroxylase-labeled neurons in the ventral midbrain. While electrochemical measurements in the striatum determined no changes in acute DA release and uptake, a small but significant decrease in DA release was detected in mutant animals after prolonged repetitive stimulation, suggesting a possible deficit in the DA neurotransmitter vesicle reserve pool. However, electron microscopy analyses did not reveal significant differences in the content of synaptic vesicles per terminal, and striatal DA levels were unchanged in DA-βcat KO animals. In contrast, striatal mRNA levels for several markers known to regulate synaptic plasticity and DA neurotransmission were altered in DA-βcat KO mice. This study demonstrates that ablation of β-catenin in DA neurons leads to alterations of motor and reward-associated memories and to adaptations of the DA neurotransmitter system and suggests that β-catenin signaling in DA neurons is required to facilitate the synaptic remodeling underlying the consolidation of long-term memories.
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Affiliation(s)
- Oscar Diaz-Ruiz
- Integrative Neuroscience Section, National Institutes of Health, Baltimore, Maryland 21224, USA
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28
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Sterky FH, Hoffman AF, Milenkovic D, Bao B, Paganelli A, Edgar D, Wibom R, Lupica CR, Olson L, Larsson NG. Altered dopamine metabolism and increased vulnerability to MPTP in mice with partial deficiency of mitochondrial complex I in dopamine neurons. Hum Mol Genet 2011; 21:1078-89. [PMID: 22090423 DOI: 10.1093/hmg/ddr537] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A variety of observations support the hypothesis that deficiency of complex I [reduced nicotinamide-adenine dinucleotide (NADH):ubiquinone oxidoreductase] of the mitochondrial respiratory chain plays a role in the pathophysiology of Parkinson's disease (PD). However, recent data from a study using mice with knockout of the complex I subunit NADH:ubiquinone oxidoreductase iron-sulfur protein 4 (Ndufs4) has challenged this concept as these mice show degeneration of non-dopamine neurons. In addition, primary dopamine (DA) neurons derived from such mice, reported to lack complex I activity, remain sensitive to toxins believed to act through inhibition of complex I. We tissue-specifically disrupted the Ndufs4 gene in mouse heart and found an apparent severe deficiency of complex I activity in disrupted mitochondria, whereas oxidation of substrates that result in entry of electrons at the level of complex I was only mildly reduced in intact isolated heart mitochondria. Further analyses of detergent-solubilized mitochondria showed the mutant complex I to be unstable but capable of forming supercomplexes with complex I enzyme activity. The loss of Ndufs4 thus causes only a mild complex I deficiency in vivo. We proceeded to disrupt Ndufs4 in midbrain DA neurons and found no overt neurodegeneration, no loss of striatal innervation and no symptoms of Parkinsonism in tissue-specific knockout animals. However, DA homeostasis was abnormal with impaired DA release and increased levels of DA metabolites. Furthermore, Ndufs4 DA neuron knockouts were more vulnerable to the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Taken together, these findings lend in vivo support to the hypothesis that complex I deficiency can contribute to the pathophysiology of PD.
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Affiliation(s)
- Fredrik H Sterky
- Department of Laboratory Medicine, Karolinska Institutet, Retzius väg 8, SE-17177 Stockholm, Sweden
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Good CH, Hoffman AF, Hoffer BJ, Chefer VI, Shippenberg TS, Bäckman CM, Larsson NG, Olson L, Gellhaar S, Galter D, Lupica CR. Impaired nigrostriatal function precedes behavioral deficits in a genetic mitochondrial model of Parkinson's disease. FASEB J 2011; 25:1333-44. [PMID: 21233488 DOI: 10.1096/fj.10-173625] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Parkinson's disease (PD) involves progressive loss of nigrostriatal dopamine (DA) neurons over an extended period of time. Mitochondrial damage may lead to PD, and neurotoxins affecting mitochondria are widely used to produce degeneration of the nigrostriatal circuitry. Deletion of the mitochondrial transcription factor A gene (Tfam) in C57BL6 mouse DA neurons leads to a slowly progressing parkinsonian phenotype in which motor impairment is first observed at ~12 wk of age. L-DOPA treatment improves motor dysfunction in these "MitoPark" mice, but this declines when DA neuron loss is more complete. To investigate early neurobiological events potentially contributing to PD, we compared the neurochemical and electrophysiological properties of the nigrostriatal circuit in behaviorally asymptomatic 6- to 8-wk-old MitoPark mice and age-matched control littermates. Release, but not uptake of DA, was impaired in MitoPark mouse striatal brain slices, and nigral DA neurons lacked characteristic pacemaker activity compared with control mice. Also, hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channel function was reduced in MitoPark DA neurons, although HCN messenger RNA was unchanged. This study demonstrates altered nigrostriatal function that precedes behavioral parkinsonian symptoms in this genetic PD model. A full understanding of these presymptomatic cellular properties may lead to more effective early treatments of PD.
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Affiliation(s)
- Cameron H Good
- Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, U.S. Department of Health and Human Services, Baltimore, MD 21224, USA
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30
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Luo Y, Good CH, Diaz-Ruiz O, Zhang Y, Hoffman AF, Shan L, Kuang SY, Malik N, Chefer VI, Tomac AC, Lupica CR, Bäckman CM. NMDA receptors on non-dopaminergic neurons in the VTA support cocaine sensitization. PLoS One 2010; 5:e12141. [PMID: 20808436 PMCID: PMC2922329 DOI: 10.1371/journal.pone.0012141] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 07/19/2010] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND The initiation of behavioral sensitization to cocaine and other psychomotor stimulants is thought to reflect N-methyl-D-aspartate receptor (NMDAR)-mediated synaptic plasticity in the mesolimbic dopamine (DA) circuitry. The importance of drug induced NMDAR mediated adaptations in ventral tegmental area (VTA) DA neurons, and its association with drug seeking behaviors, has recently been evaluated in Cre-loxp mice lacking functional NMDARs in DA neurons expressing Cre recombinase under the control of the endogenous dopamine transporter gene (NR1(DATCre) mice). METHODOLOGY AND PRINCIPAL FINDINGS Using an additional NR1(DATCre) mouse transgenic model, we demonstrate that while the selective inactivation of NMDARs in DA neurons eliminates the induction of molecular changes leading to synaptic strengthening, behavioral measures such as cocaine induced locomotor sensitization and conditioned place preference remain intact in NR1(DATCre) mice. Since VTA DA neurons projecting to the prefrontal cortex and amygdala express little or no detectable levels of the dopamine transporter, it has been speculated that NMDA receptors in DA neurons projecting to these brain areas may have been spared in NR1(DATCre) mice. Here we demonstrate that the NMDA receptor gene is ablated in the majority of VTA DA neurons, including those exhibiting undetectable DAT expression levels in our NR1(DATCre) transgenic model, and that application of an NMDAR antagonist within the VTA of NR1(DATCre) animals still blocks sensitization to cocaine. CONCLUSIONS/SIGNIFICANCE These results eliminate the possibility of NMDAR mediated neuroplasticity in the different DA neuronal subpopulations in our NR1(DATCre) mouse model and therefore suggest that NMDARs on non-DA neurons within the VTA must play a major role in cocaine-related addictive behavior.
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Affiliation(s)
- Yu Luo
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Cameron H. Good
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Oscar Diaz-Ruiz
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
| | - YaJun Zhang
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Alexander F. Hoffman
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Lufei Shan
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Serena Y. Kuang
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Nasir Malik
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Vladimir I. Chefer
- Behavioral Neuroscience Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Andreas C. Tomac
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Carl R. Lupica
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Cristina M. Bäckman
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland, United States of America
- * E-mail:
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Li X, Hoffman AF, Peng XQ, Lupica CR, Gardner EL, Xi ZX. Attenuation of basal and cocaine-enhanced locomotion and nucleus accumbens dopamine in cannabinoid CB1-receptor-knockout mice. Psychopharmacology (Berl) 2009; 204:1-11. [PMID: 19099297 PMCID: PMC3729960 DOI: 10.1007/s00213-008-1432-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Accepted: 12/01/2008] [Indexed: 11/24/2022]
Abstract
RATIONALE Effect of cannabinoid CB1 receptor deletion on cocaine's actions is controversial. This is partly based on findings in CB1-receptor-knockout (CB1(-/-)) mice with CD1 genetic background. OBJECTIVES In the present study, we used CB1(-/-) mice with a C57BL/6J genetic background to further investigate the role of CB1 receptors in cocaine's action. MATERIALS AND METHODS Locomotor activity was assessed using AccuScan locomotor chambers. Brain extracellular dopamine (DA) levels were measured by in vivo microdialysis and by fast-scan cyclic voltammetry in the nucleus accumbens (NAc). RESULTS CB1(-/-) mice displayed a significant reduction in basal levels of locomotion and extracellular DA, as well as in cocaine-enhanced locomotion and extracellular DA, as compared to their wild-type (CB1(+/+)) littermates. The reduction in basal and cocaine-enhanced DA appears to be related to a reduction in basal DA release, not to an increase in DA clearance, as indicated by fast-scan cyclic voltammetry in brain slices. Pharmacological blockade of CB1 receptors by SR141716 inhibited locomotion and NAc DA release in CB1(+/+) mice. CONCLUSIONS The present findings suggest an important role for CB1 receptors in mediating cocaine's behavioral and neurochemical effects.
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Affiliation(s)
- Xia Li
- Neuropsychopharmacology Section, Chemical Biology Research Branch, National Institute on Drug Abuse, Baltimore, MD 21224, USA
| | - Alexander F. Hoffman
- Neurophysiology Section, Cellular Neurobiology Research Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore MD 21224 USA
| | - Xiao-Qing Peng
- Neuropsychopharmacology Section, Chemical Biology Research Branch, National Institute on Drug Abuse, Baltimore, MD 21224, USA
| | - Carl R. Lupica
- Neurophysiology Section, Cellular Neurobiology Research Branch, Intramural Research Program, National Institute on Drug Abuse, Baltimore MD 21224 USA
| | - Eliot L. Gardner
- Neuropsychopharmacology Section, Chemical Biology Research Branch, National Institute on Drug Abuse, Baltimore, MD 21224, USA
| | - Zheng-Xiong Xi
- Neuropsychopharmacology Section, Chemical Biology Research Branch, National Institute on Drug Abuse, Baltimore, MD 21224, USA
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Fan H, Kotsikorou E, Hoffman AF, Ravert HT, Holt D, Hurst DP, Lupica CR, Reggio PH, Dannals RF, Horti AG. Analogs of JHU75528, a PET ligand for imaging of cerebral cannabinoid receptors (CB1): development of ligands with optimized lipophilicity and binding affinity. Eur J Med Chem 2008; 44:593-608. [PMID: 18511157 DOI: 10.1016/j.ejmech.2008.03.040] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 03/21/2008] [Accepted: 03/27/2008] [Indexed: 11/16/2022]
Abstract
Cyano analogs of Rimonabant with high binding affinity for the cerebral cannabinoid receptor (CB1) and with optimized lipophilicity have been synthesized as potential positron emission tomography (PET) ligands. The best ligands of the series are optimal targets for the future radiolabeling with PET isotopes and in vivo evaluation as radioligands with enhanced properties for PET imaging of CB1 receptors in human subjects. Extracellular electrophysiological recordings in rodent brain slices demonstrated that JHU75528, 4, the lead compound of the new series, has functional CB antagonist properties that are consistent with its structural relationship to Rimonabant. Molecular modeling analysis revealed an important role of the binding of the cyano group with the CB1 binding pocket.
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Affiliation(s)
- Hong Fan
- PET Center, Division of Nuclear Medicine, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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Chen YH, Harvey BK, Hoffman AF, Wang Y, Chiang YH, Lupica CR. MPTP-induced deficits in striatal synaptic plasticity are prevented by glial cell line-derived neurotrophic factor expressed via an adeno-associated viral vector. FASEB J 2007; 22:261-75. [PMID: 17690153 DOI: 10.1096/fj.07-8797com] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study determined the consequences of dopamine denervation of the striatum on synaptic plasticity and prevention of these changes with gene therapy using an adeno-associated viral vector (AAV) expressing glial cell line-derived neurotrophic factor (GDNF). C57BL6/J mice were injected with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP); long-term depression (LTD) or potentiation (LTP) were measured in vitro. Fast-scan cyclic voltammetry measured electrically released dopamine from a functionally relevant pool in these same striatal slices. After MPTP, dopamine release and uptake were greatly diminished, and LTP and LTD were blocked in the striatal slices. The loss of plasticity resulted directly from the loss of dopamine since its application rescued synaptic plasticity. Striatal GDNF expression via AAV, before MPTP, significantly protected against the loss of dopamine and prevented the blockade of corticostriatal LTP. These data demonstrate that dopamine plays a role in supporting several forms of striatal plasticity and that GDNF expression via AAV prevents the loss of dopamine and striatal plasticity caused by MPTP. We propose that impairment of striatal plasticity after dopamine denervation plays a role in the symptomology of Parkinson's disease and that AAV expression of neurotrophic factors represents a tenable approach to protecting against or slowing these neurobiological deficits.
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Affiliation(s)
- Yuan-Hao Chen
- Program of Clinical Medicine, Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
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Hoffman AF, Oz M, Yang R, Lichtman AH, Lupica CR. Opposing actions of chronic Delta9-tetrahydrocannabinol and cannabinoid antagonists on hippocampal long-term potentiation. Learn Mem 2007; 14:63-74. [PMID: 17202425 PMCID: PMC1828281 DOI: 10.1101/lm.439007] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Memory deficits produced by marijuana arise partly via interaction of the psychoactive component, Delta(9)-tetrahydrocannabinol (Delta(9)-THC), with cannabinoid receptors in the hippocampus. Although cannabinoids acutely reduce glutamate release and block hippocampal long-term potentiation (LTP), a potential substrate for learning and memory, the consequences of prolonged exposure to Delta(9)-THC for hippocampal function are poorly understood. Rats were injected with Delta(9)-THC (10 mg/kg, i.p., q.d.) for 1, 3, or 7 d, and electrophysiological recordings were performed in hippocampal slices 1d after the final injection. At this time, Delta(9)-THC was undetectable in hippocampus using liquid chromatography-mass spectrometry (LC-MS). Hippocampal LTP generated using high-frequency (HFS) or theta burst stimulation was not observed in brain slices from the 7-d Delta(9)-THC-treated animals. Delta(9)-THC also blocked HFS-LTP after 3 d, but not 1 d of treatment. The complete blockade of LTP persisted for 3 d after the last Delta(9)-THC injection, and full reversal of the LTP deficit was not observed up to 14 d following Delta(9)-THC withdrawal. The cannabinoid antagonist AM251 (2 mg/kg), administered before each Delta(9)-THC injection prevented the blockade of LTP, and 7-d treatment with AM251 alone significantly increased the level of LTP. Chronic Delta(9)-THC also produced tolerance to the inhibition of synaptic GABA, but not glutamate release by the agonist WIN55,212-2. These data define consequences of repeated Delta(9)-THC exposure for synaptic plasticity in the hippocampus that may help explain memory impairments in humans following chronic marijuana use.
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Affiliation(s)
- Alexander F. Hoffman
- United States Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse, Intramural Research Program, Cellular Neurobiology Branch, Electrophysiology Research Unit, Baltimore, Maryland 21224, USA
| | - Murat Oz
- United States Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse, Intramural Research Program, Cellular Neurobiology Branch, Electrophysiology Research Unit, Baltimore, Maryland 21224, USA
| | - Ruiqin Yang
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia 23298-0613, USA
| | - Aron H. Lichtman
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia 23298-0613, USA
| | - Carl R. Lupica
- United States Department of Health and Human Services, National Institutes of Health, National Institute on Drug Abuse, Intramural Research Program, Cellular Neurobiology Branch, Electrophysiology Research Unit, Baltimore, Maryland 21224, USA
- Corresponding author.E-mail ; fax (410) 550-1621
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Hoffman AF, Macgill AM, Smith D, Oz M, Lupica CR. Species and strain differences in the expression of a novel glutamate-modulating cannabinoid receptor in the rodent hippocampus. Eur J Neurosci 2006; 22:2387-91. [PMID: 16262678 PMCID: PMC1351024 DOI: 10.1111/j.1460-9568.2005.04401.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel, non-CB1 cannabinoid receptor has been defined by the persistence of inhibition of glutamatergic EPSPs by the cannabinoid receptor agonist WIN55,212-2 in mice lacking the cloned CB1 receptor (CB1-/-) (Hajos et al., 2001). This novel receptor was also distinguished from CB1 by its sensitivity to the antagonist SR141716A and its insensitivity to the antagonist AM251 (Hajos & Freund, 2002). We have chosen to refer to this putative receptor as CBsc due to its identification on Schaffer collateral axon terminals in the hippocampus. We examined properties of CBsc receptors in Sprague Dawley (SD) rats and two strains of wild-type (WT) mice (C57BL/6J and CD1) used as backgrounds for two independent lines of CB1-/- mice (Ledent et al., 1999; Zimmer et al., 1999). The inhibition of synaptic glutamate release by WIN55,212-2 was observed in hippocampal slices from WT CD1 mice and SD rats but was absent in WT C57 mice. We also found that AM251 and SR141716A antagonized the effect of WIN55,212-2 in hippocampal slices from CD1 mice and SD rats demonstrating a lack of selectivity of these ligands for CB1 and CBsc receptors in these animals. The results indicate that the glutamate-modulating CBsc cannabinoid receptor is present in the hippocampi of CD1 mice and SD rats but not in C57BL/6J mice. Thus, we have identified animal models that may permit the study of cannabinoids independently of the novel CBsc receptor (C57CB1+/+), the CBsc receptor independently of the cloned CB1 receptor (CD1CB1-/-), or in the absence of both receptors (C57CB1-/-).
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Affiliation(s)
- Alexander F. Hoffman
- Neurophysiology Section, Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Department of Health and Human Services, Baltimore, MD 21224, USA
| | - Alice M. Macgill
- Neurophysiology Section, Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Department of Health and Human Services, Baltimore, MD 21224, USA
- Oberlin College Neuroscience Department, Oberlin, OH, USA
| | - Dennison Smith
- Oberlin College Neuroscience Department, Oberlin, OH, USA
| | - Murat Oz
- Neurophysiology Section, Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Department of Health and Human Services, Baltimore, MD 21224, USA
| | - Carl R. Lupica
- Neurophysiology Section, Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Department of Health and Human Services, Baltimore, MD 21224, USA
- Correspondence: Dr Carl R. Lupica, as above. E-mail:
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Hoffman AF, Lupica CR. Visualizing cannabinoid effects using brain slice imaging and electrophysiological approaches. Methods Mol Med 2006; 123:105-12. [PMID: 16506404 DOI: 10.1385/1-59259-999-0:105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The use of electrophysiological recordings in brain slices is now routinely used to assess the actions of cannabinoid ligands within various central nervous system nuclei. In this chapter we describe common protocols involving both intracellular and extracellular recording techniques in the hippocampus, where the presynaptic modulatory effects of cannabinoid receptor activation have been studied in detail. In addition to describing the basic electrophysiological setup needed for these recordings, we will address common technical problems and limitations involved in working with highly lipophilic compounds, such as the cannabinoid ligands, in brain slices.
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Affiliation(s)
- Alexander F Hoffman
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
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Abstract
The reward circuitry of the brain consists of neurons that synaptically connect a wide variety of nuclei. Of these brain regions, the ventral tegmental area (VTA) and the nucleus accumbens (NAc) play central roles in the processing of rewarding environmental stimuli and in drug addiction. The psychoactive properties of marijuana are mediated by the active constituent, Delta(9)-THC, interacting primarily with CB1 cannabinoid receptors in a large number of brain areas. However, it is the activation of these receptors located within the central brain reward circuits that is thought to play an important role in sustaining the self-administration of marijuana in humans, and in mediating the anxiolytic and pleasurable effects of the drug. Here we describe the cellular circuitry of the VTA and the NAc, define the sites within these areas at which cannabinoids alter synaptic processes, and discuss the relevance of these actions to the regulation of reinforcement and reward. In addition, we compare the effects of Delta(9)-THC with those of other commonly abused drugs on these reward circuits, and we discuss the roles that endogenous cannabinoids may play within these brain pathways, and their possible involvement in regulating ongoing brain function, independently of marijuana consumption. We conclude that, whereas Delta(9)-THC alters the activity of these central reward pathways in a manner that is consistent with other abused drugs, the cellular mechanism through which this occurs is likely different, relying upon the combined regulation of several afferent pathways to the VTA.
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Affiliation(s)
- Carl R Lupica
- Neurophysiology Section, Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, U.S. Department of Health and Human Services, Baltimore, MD 21224, USA.
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Hoffman AF, Riegel AC, Lupica CR. Functional localization of cannabinoid receptors and endogenous cannabinoid production in distinct neuron populations of the hippocampus. Eur J Neurosci 2003; 18:524-34. [PMID: 12911748 DOI: 10.1046/j.1460-9568.2003.02773.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The possible localization of cannabinoid (CB) receptors to glutamatergic and GABAergic synaptic terminals impinging upon GABAergic interneurons in the CA1 region of the rat hippocampus was examined using the electrophysiological measurement of neurotransmitter release in brain slices. Whereas activation of cannabinoid receptors via the application of the cannabinoid agonist WIN55,212-2 significantly and dose-dependently reduced evoked IPSCs recorded from interneurons possessing somata located in the stratum radiatum (S.R.) and stratum oriens (S.O.) lamellae, evoked glutamatergic EPSCs were unaffected in both neuronal populations. However, in agreement with previous reports, WIN55,212-2 significantly reduced EPSCs recorded from CA1 pyramidal neurons. Additional experiments confirmed that the effects of WIN55,212-2 on IPSCs were presynaptic and that they could be blocked by the CB1 receptor antagonist SR141716A. The involvement of endogenous cannabinoids in the presynaptic inhibition of GABA release was also examined in the interneurons and pyramidal cells using a depolarization-induced suppression of inhibition (DSI) paradigm. DSI was observed in CA1 pyramidal neurons under control conditions, and its incidence was greatly increased by the cholinergic agonist carbachol. However, DSI was not observed in the S.R. or S.O. interneuron populations, in either the presence or absence of carbachol. Whereas DSI was not present in these interneurons, the inhibitory inputs to these cells were modulated by the synthetic cannabinoid WIN55,212-2. These data support the hypothesis that cannabinoid receptors are located on inhibitory, but not excitatory, axon terminals impinging upon hippocampal interneurons, and that CA1 pyramidal neurons, and not interneurons, are capable of generating endogenous cannabinoids during prolonged states of depolarization.
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Affiliation(s)
- Alexander F Hoffman
- Cellular Neurobiology Research Branch, National Institute on Drug Abuse, National Institutes of Health, US Department of Health and Human Services, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA
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Hoffman AF, Oz M, Caulder T, Lupica CR. Functional tolerance and blockade of long-term depression at synapses in the nucleus accumbens after chronic cannabinoid exposure. J Neurosci 2003; 23:4815-20. [PMID: 12832502 PMCID: PMC6741179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
Abstract
The rewarding properties of the psychoactive constituents of marijuana, termed "cannabinoids," may reflect actions on synaptic transmission in the nucleus accumbens (NAc). Furthermore, long-term changes in these synapses may support the addictive process. Excitatory and inhibitory synapses are acutely inhibited by cannabinoids in the NAc, and endogenous cannabinoids (endocannabinoids) play a critical role in the expression of long-term depression (LTD) of excitatory cortical afferents in this structure. Because humans often use marijuana for prolonged periods, we examined the impact of long-term cannabinoid exposure on synaptic processes in an animal model. Electrophysiological recordings in rat brain slices containing the NAc were performed after chronic exposure to vehicle solution, Delta9-tetrahydrocannabinol (THC), or the cannabinoid agonist R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-(1-naphthalenyl)methanone mesylate (WIN55,212-2). Extracellular glutamatergic postsynaptic potentials and whole-cell GABAergic IPSCs were concentration-dependently inhibited by WIN55,212-2 in slices from naive or vehicle-treated animals. However, the sensitivity to WIN55,212-2 was diminished in chronic agonist-treated animals. In addition, cross-tolerance to the inhibitory effect of the mu-opioid agonist Tyr-D-Ala2, N-CH3-Phe4,Gly-ol-enkephalin was observed. Endocannabinoid-mediated LTD was initiated via electrical stimulation (5 min, 10 Hz) of glutamatergic afferents to the NAc and was completely blocked by the cannabinoid receptor antagonist SR141716A [N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide] in vehicle-treated animals. LTD was not observed in brain slices from rats chronically treated with Delta9-THC or WIN55,212-2. These data demonstrate that long-term exposure to the active ingredient of marijuana blocks synaptic plasticity in the NAc and reduces the sensitivity of GABAergic and glutamatergic synapses to both cannabinoids and opioids.
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Affiliation(s)
- Alexander F Hoffman
- Cellular Neurobiology Branch, Section on Cellular Neurophysiology, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, United States Department of Health and Human Services, Baltimore, Maryland 21224, USA
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Katoch-Rouse R, Pavlova OA, Caulder T, Hoffman AF, Mukhin AG, Horti AG. Synthesis, structure-activity relationship, and evaluation of SR141716 analogues: development of central cannabinoid receptor ligands with lower lipophilicity. J Med Chem 2003; 46:642-5. [PMID: 12570386 DOI: 10.1021/jm020157x] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Exploration of the central CB1 cannabinoid receptors using positron emission tomography (PET) will allow for an understanding of the pharmacological and physiological role played by these receptors in the CNS. Current tracers are highly lipophilic compounds that exhibit very high nonspecific to specific binding ratios and as a result are inapt for use in humans. We have synthesized a series of less lipophilic analogues of SR141716 to serve as potential radioligands. Binding affinities of the series and a functional electrophysiological assay of three of our compounds have been presented.
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Affiliation(s)
- Reeti Katoch-Rouse
- Neuroimaging Research Branch and Cellular Neurophysiology Section, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 5500 Nathan Shock Drive, Baltimore, Maryland 21224, USA
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Gerhardt GA, Hoffman AF. Effects of recording media composition on the responses of Nafion-coated carbon fiber microelectrodes measured using high-speed chronoamperometry. J Neurosci Methods 2001; 109:13-21. [PMID: 11489295 DOI: 10.1016/s0165-0270(01)00396-x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The present study concerns methodological issues of electrochemical recordings using Nafion-coated 30 microm diameter single carbon fiber microelectrodes for high-speed chronoamperometric measurements of biogenic amines. First, the single carbon fiber microelectrodes were coated with Nafion and dried at 85 vs. 200 degrees C and their recording properties were determined. Second, the effects of shifts in solution pH, ionic strength, changes in recording solution levels of Ca(2+) or Mg(2+) and temperature on the recording characteristics and sensitivity of Nafion-coated high temperature dried (200 degrees C) single carbon fiber microelectrodes for measures of dopamine were studied. These studies showed that the high temperature drying of the Nafion produced a microelectrode with better recording properties: higher selectivity for cations versus anions, increased differences between the reduction and oxidation current ratios for the identification of dopamine versus serotonin, and more rapid response times. In addition, these studies demonstrated that the chronoamperometric recordings were insensitive to small changes in pH and divalent cations such as Ca(2+) or Mg(2+). However, increases in ionic strength decreased the sensitivity of the microelectrodes, while increases in temperature produced increases in the sensitivity of the microelectrodes for biogenic amines. These data support that Nafion-coated high temperature (200 degrees C) dried microelectrodes have enhanced recording properties as compared to microelectrodes, which are coated with Nafion and dried at 85 degrees C. In addition, high-speed chronoamperometric recordings of biogenic amines are not affected by solution changes in divalent cations (Ca(2+) or Mg(2+)).
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Affiliation(s)
- G A Gerhardt
- Department of Anatomy and Neurobiology and the Morris K. Udall Parkinson's Disease Research Center of Excellence, 306 Davis Mills Bldg., University of Kentucky, Chandler Medical Center, 800 Rose Street, Lexington, KT 40536-0098, USA.
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Lupica CR, Bell JA, Hoffman AF, Watson PL. Contribution of the hyperpolarization-activated current (I(h)) to membrane potential and GABA release in hippocampal interneurons. J Neurophysiol 2001; 86:261-8. [PMID: 11431507 DOI: 10.1152/jn.2001.86.1.261] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Intrinsic GABAergic interneurons provide inhibitory input to the principal neurons of the hippocampus. The majority of interneurons located in stratum oriens (s.o.) of the CA1 region express the hyperpolarization-activated cation current known as I(h). In an effort to elucidate the role of this current in regulating the baseline excitability of these neurons and its participation in the regulation of the release of GABA onto CA1 pyramidal neurons, we utilized whole cell electrophysiological recordings from both populations of cells. In voltage-clamp experiments, hyperpolarization of the interneuron membrane initiated a large inward current with an estimated activation threshold of 51.6 +/- 7.6 mV and a half-maximal voltage of -73.0 +/- 7.0 mV. This current was blocked by bath application of the I(h) inhibitors ZD 7288 (50 microM) or cesium (2 mM). Current-clamp experiments at the interneuron resting membrane potential (-61.3 +/- 1.2 mV) revealed a significant hyperpolarization, a decrease in the rate of spontaneous action potential discharge, an increase in the cellular input resistance, and the elimination of rebound afterdepolarizations during blockade of I(h) with ZD 7288 (50 microM). The hyperpolarizing effect of ZD 7288 was also substantially larger in interneurons clamped near -80 mV using current injection through the pipette. In addition to neurons exhibiting I(h), recordings were obtained from a small population of s.o. interneurons that did not exhibit this current. These cells demonstrated resting membrane potentials that were significantly more negative (-73.6 +/- 5.5 mV) than those observed in neurons expressing I(h), suggesting that this current contributes to more depolarized membrane potentials in these cells. Recordings from postsynaptic pyramidal neurons demonstrated that blockade of I(h) with ZD 7288 caused a substantial reduction (approximately 43%) in the frequency of spontaneous action potential-dependent inhibitory postsynaptic currents (IPSCs), without altering their average amplitude. However, miniature action-potential-independent IPSC frequency, amplitude, and decay kinetics were unaltered by ZD 7288. These data suggest that I(h) is active at the resting membrane potential in s.o. interneurons and as a result contributes to the spontaneous activity of these cells and to the tonic inhibition of CA1 pyramidal neurons in the hippocampus.
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Affiliation(s)
- C R Lupica
- Department of Pharmacology, University of Arizona Health Sciences Center, Tucson, Arizona 85724, USA.
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Abstract
The nucleus accumbens (NAc) represents a critical site for the rewarding and addictive properties of several classes of abused drugs. The medium spiny GABAergic projection neurons (MSNs) in the NAc receive innervation from intrinsic GABAergic interneurons and glutamatergic innervation from extrinsic sources. Both GABA and glutamate release onto MSNs are inhibited by drugs of abuse, suggesting that this action may contribute to their rewarding properties. To investigate the actions of cannabinoids in the NAc, we performed whole cell recordings from MSNs located in the shell region in rat brain slices. The cannabinoid agonist WIN 55,212-2 (1 microM) had no effect on the resting membrane potential, input resistance, or whole cell conductance, suggesting no direct postsynaptic effects. Evoked glutamatergic excitatory postsynaptic currents (EPSCs) were inhibited to a much greater extent by [Tyr-D-Ala(2), N-CH(3)-Phe(4), Gly-ol-enkephalin] (DAMGO, approximately 35%) than by WIN 55,212-2 (<20%), and an analysis of miniature EPSCs suggested that the effects of DAMGO were presynaptic, whereas those of WIN 55,212-2 were postsynaptic. However, electrically evoked GABAergic inhibitory postsynaptic currents (evIPSCs), were reduced by WIN 55,212-2 in every neuron tested (EC(50) = 123 nM; 60% maximal inhibition), and the inhibition of IPSCs by WIN 55,212-2 was completely antagonized by the CB1 receptor antagonist SR141716A (1 microM). In contrast evIPSCs were inhibited in approximately 50% of MSNs by the mu/delta opioid agonist D-Ala(2)-methionine(2)-enkephalinamide and were completely unaffected by a selective mu-opioid receptor agonist (DAMGO). WIN 55,212-2 also increased paired-pulse facilitation of the evIPSCs and did not alter the amplitudes of tetrodotoxin-resistant miniature IPSCs, suggesting a presynaptic action. Taken together, these data suggest that cannabinoids and opioids differentially modulate inhibitory and excitatory synaptic transmission in the NAc and that the abuse liability of marijuana may be related to the direct actions of cannabinoids in this structure.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Benzoxazines
- Cannabinoids/pharmacology
- Electric Stimulation
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Enkephalin, Methionine/analogs & derivatives
- Enkephalin, Methionine/pharmacology
- Evoked Potentials/drug effects
- Excitatory Amino Acid Antagonists/pharmacology
- Excitatory Postsynaptic Potentials/drug effects
- GABA-B Receptor Agonists
- In Vitro Techniques
- Male
- Membrane Potentials/drug effects
- Morpholines/pharmacology
- Naphthalenes/pharmacology
- Narcotics/pharmacology
- Neurons/classification
- Neurons/cytology
- Neurons/drug effects
- Neurons/metabolism
- Nucleus Accumbens/drug effects
- Nucleus Accumbens/physiology
- Patch-Clamp Techniques
- Rats
- Rats, Sprague-Dawley
- Receptors, Cannabinoid
- Receptors, Drug/agonists
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/metabolism
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
- Tetrodotoxin/pharmacology
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Affiliation(s)
- A F Hoffman
- Cellular Neurobiology Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA
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Hoffman AF, Lupica CR. Mechanisms of cannabinoid inhibition of GABA(A) synaptic transmission in the hippocampus. J Neurosci 2000; 20:2470-9. [PMID: 10729327 PMCID: PMC6772239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
The localization of cannabinoid (CB) receptors to GABAergic interneurons in the hippocampus indicates that CBs may modulate GABAergic function and thereby mediate some of the disruptive effects of marijuana on spatial memory and sensory processing. To investigate the possible mechanisms through which CB receptors may modulate GABAergic neurotransmission in the hippocampus, whole-cell voltage-clamp recordings were performed on CA1 pyramidal neurons in rat brain slices. Stimulus-evoked GABA(A) receptor-mediated IPSCs were reduced in a concentration-dependent manner by the CB receptor agonist WIN 55,212-2 (EC(50) of 138 nM). This effect was blocked by the CB1 receptor antagonist SR141716A (1 microM) but not by the opioid antagonist naloxone. In contrast, evoked GABA(B)-mediated IPSCs were insensitive to the CB agonist. WIN 55,212-2 also reduced the frequency of spontaneous, action potential-dependent IPSCs (sIPSCs), without altering action potential-independent miniature IPSCs (mIPSCs), measured while sodium channels were blocked by tetrodotoxin (TTX). Blockade of voltage-dependent calcium channels (VDCCs) by cadmium also eliminated the effect of WIN 55,212-2 on sIPSCs. Depolarization of inhibitory terminals with elevated extracellular potassium caused a large increase in the frequency of mIPSCs that was inhibited by both cadmium and WIN 55,212-2. The presynaptic effect of WIN 55,212-2 was also investigated using the potassium channel blockers barium and 4-aminopyridine. Neither of these agents significantly altered the effect of WIN 55,212-2 on evoked IPSCs. Together, these data suggest that presynaptic CB1 receptors reduce GABA(A)- but not GABA(B)-mediated synaptic inhibition of CA1 pyramidal neurons by inhibiting VDCCs located on inhibitory nerve terminals.
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Affiliation(s)
- A F Hoffman
- Cellular Neurobiology Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, Maryland 21224, USA
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Hoffman AF, Gerhardt GA. Differences in pharmacological properties of dopamine release between the substantia nigra and striatum: an in vivo electrochemical study. J Pharmacol Exp Ther 1999; 289:455-63. [PMID: 10087038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Abstract
The properties of dopamine (DA) release in the rat substantia nigra (SN) and striatum were investigated using high-speed chronoamperometric recordings in brain slices. In both brain regions, a 2-min bath superfusion with 30 mM KCl produced robust DA-like electrochemical signals, with the mean amplitude of the signal being >10-fold greater in the striatum than the SN. The reproducibility of the response was confirmed by a second stimulus (S2)/first-stimulus (S1) ratio of >0.8 in both regions. The bath application of tetrodotoxin significantly reduced the S2/S1 ratio in both the striatum and SN, implicating the requirement for voltage-sensitive sodium channels in the DA-release process. However, the application of cadmium chloride, a nonselective blocker of voltage-sensitive calcium channels, reduced the S2/S1 ratio only in the striatum and not within the SN. Moreover, removal of Ca2+ from the buffer did not significantly affect release within the SN, despite a >85% reduction in release within the striatum. In addition, although the D2 receptor antagonist sulpiride enhanced the S2/S1 ratio in the striatum, no effect of this agent was seen in the SN. Finally, the application of d-amphetamine produced DA-like electrochemical signals in both the striatum and SN. However, the amplitude of the d-amphetamine-evoked response, relative to the KCl-evoked release, was much smaller in the striatum than in the SN. Taken together, these data support the hypothesis that differences in the mechanism or mechanisms of release exist between somatodendritic and axonal elements within the nigrostriatal pathway.
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Affiliation(s)
- A F Hoffman
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver, Colorado, USA
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Abstract
The possible voltage-dependence of the dopamine transporter (DAT) was investigated using electrophysiological and electrochemical recordings in rat brain slices containing the substantia nigra (SN). Whole-cell patch clamp recordings of DA neurons, revealed that addition of 15 mM KCl rapidly depolarized the membrane potential by approximately 20 mV, whereas these cells were hyperpolarized approximately 10 mV by DA (10 microM) and approximately 14 mV by the GABAB-receptor agonist baclofen (30 microM). High-speed chronoamperometric recordings were used to monitor clearance properties of exogenously applied DA signals during similar manipulations. Superfusion of slices with 15 mM KCl significantly increased the time course of the DA signal, consistent with inhibition of DAT activity. Application of the D2 DA-receptor antagonist sulpiride (50 microM) also significantly increased the time course, suggesting that DA-induced hyperpolarization enhances DAT activity. Baclofen reversed the effects of sulpiride on DA clearance. These results demonstrate that changes in DA cell membrane potential can modulate DAT activity.
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Affiliation(s)
- A F Hoffman
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80262, USA
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Hoffman AF, Lupica CR, Gerhardt GA. Dopamine transporter activity in the substantia nigra and striatum assessed by high-speed chronoamperometric recordings in brain slices. J Pharmacol Exp Ther 1998; 287:487-96. [PMID: 9808671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
High-speed chronoamperometric measurements were used to measure clearance of locally applied dopamine (DA) in rat brain slices containing the substantia nigra (SN) or striatum. A comparison of DA signals of similar amplitudes between brain regions revealed that DA clearance was more rapid in the striatum than in the SN, consistent with the known greater distribution of the dopamine transporter (DAT) in the striatum. To clarify the role of the DAT in mediating DA clearance within the SN, slices were superfused with uptake inhibitors with different selectivities for the various monoamine transporters. In the SN, both cocaine and nomifensine significantly increased the amplitude and time course of the DA electrochemical signal. However, neither the serotonin transporter (SERT) inhibitor citalopram nor the norepinephrine transporter (NET) inhibitor desipramine (DMI) produced significant effects on DA clearance. In addition, cocaine and nomifensine affected the clearance parameters of the DA electrochemical signal to a similar extent in both the striatum and the SN, further confirming the functional role of the DAT in both brain regions. Local applications of d-amphetamine resulted in slow, prolonged DA-like electrochemical signals in both the SN and striatum, although the amplitude of the evoked response was larger within the striatum. In contrast, KCl-evoked depolarizations yielded rapid, detectable DA-like signals only within the striatum. Taken together, these data demonstrate the functional role of DAT in mediating DA clearance and release within both the striatum and SN.
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Affiliation(s)
- A F Hoffman
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver, Colorado, USA
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Abstract
The effects of cholinergic agonists on nitric oxide (NO) release in hippocampal slices from male Sprague-Dawley rats were investigated using electrochemical recording procedures using Nafion and O-phenylenediamine-treated carbon fiber microelectrodes. These microelectrodes are highly selective for NO versus other interferents. Acetylcholine (Ach) with neostigmine, or nicotine was delivered by pressure ejection from pipettes placed within 300 microm of the NO sensors. Both Ach and nicotine produced NO signals ranging from 0.04 to 2.14 microM in the CA1, CA3, and dentate gyrus of the rat hippocampus that lasted for 2-5 min. The Ach responses were not antagonized by the muscarinic antagonist atropine. However, nicotine-evoked responses were partially antagonized by alpha-bungarotoxin, a finding consistent with alpha7-nicotinic cholinergic receptors being involved with the effects of nicotine. These data support the hypothesis that nicotine is capable of evoking long lasting NO release in the hippocampus.
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Affiliation(s)
- D A Smith
- Neuroscience Program, Oberlin College, OH 44074, USA
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Hoffman AF, Gerhardt GA. In vivo electrochemical studies of dopamine clearance in the rat substantia nigra: effects of locally applied uptake inhibitors and unilateral 6-hydroxydopamine lesions. J Neurochem 1998; 70:179-89. [PMID: 9422361 DOI: 10.1046/j.1471-4159.1998.70010179.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
High-speed chronoamperometric recordings were used to measure the uptake and clearance of locally applied dopamine (DA) within the substantia nigra (SN) of anesthetized rats. To establish that DA clearance within the SN was mediated primarily by the DA transporter (DAT) rather than the norepinephrine transporter (NET) or the serotonin transporter (SERT), we locally applied uptake inhibitors with different selectivity profiles for the various amine transporters. Nomifensine, a DAT/NET inhibitor, significantly potentiated both the amplitude and the time course of the DA signals. In contrast, neither the selective NET inhibitor desipramine, nor the selective SERT inhibitor citalopram affected the DA signal, suggesting that NET and SERT do not contribute to DA uptake and clearance within the regions of the SN studied over the concentration ranges (1-5 microM) used. In unilaterally 6-hydroxydopamine-lesioned rats, the time course of the DA signal was increased in both the lesioned SN and striatum, relative to the unlesioned hemisphere, indicating loss of DAT and decreased DA uptake and clearance. In addition, when identical amounts of DA were injected in the striatum and SN, peak signal amplitudes were larger in the SN, suggesting that the amplitudes are related to the number of DAT sites in a given region of brain tissue. For signals of equivalent amplitudes, clearance rates were lower in the SN than in the striatum, consistent with a lower capacity for DAT-mediated DA uptake within the SN. These results suggest that the DAT is the major transporter responsible for DA clearance within the rat SN.
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Affiliation(s)
- A F Hoffman
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80262, USA
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Affiliation(s)
- N R Zahniser
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80262, USA
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