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Huang S, Riley AL. Drug discrimination learning: Interoceptive stimulus control of behavior and its implications for regulated and dysregulated drug intake. Pharmacol Biochem Behav 2024; 244:173848. [PMID: 39137873 DOI: 10.1016/j.pbb.2024.173848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 08/06/2024] [Accepted: 08/09/2024] [Indexed: 08/15/2024]
Abstract
Drug discrimination research has generated rich evidence for the capacity of interoceptive drug stimuli to control behavior by serving as discriminative cues. Owing to its neuropharmacological specificity, drug discrimination learning has been widely used to characterize the stimulus effects and neuropharmacological underpinning of drugs. Apart from such utility, discriminative drug stimuli may help regulate drug use by disambiguating conditioned associations and post-intake outcomes. First, this review summarizes the evidence supporting interoceptive regulation of drug intake from the literature of exteroceptive discriminative control of drug-related behavior, effects of drug priming, and self-titration of drug intake. Second, an overview of interoceptive control of reward-seeking and the animal model of discriminated goal-tracking is provided to illustrate interoceptive stimulus control of the initiation and patterning of drug intake. Third, we highlight the importance of interoceptive control of aversion-avoidance in the termination of drug-use episodes and describe the animal model of discriminated taste avoidance that supports such a position. In bridging these discriminative functions of drug stimuli, we propose that interoceptive drug stimuli help regulate intake by disambiguating whether intake will be rewarding, nonrewarding, or aversive. The reflection and discussion on current theoretical formulations of interoceptive control of drug intake may further scientific advances to improve animal models to study the mechanisms by which interoceptive stimuli regulate drug intake, as well as how alterations of interoceptive processes may contribute to the transition to dysregulated drug use.
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Affiliation(s)
- Shihui Huang
- Psychopharmacology Laboratory, Department of Neuroscience, Center for Neuroscience and Behavior, American University, 4400 Massachusetts Ave, NW, Washington, DC 20016, USA.
| | - Anthony L Riley
- Psychopharmacology Laboratory, Department of Neuroscience, Center for Neuroscience and Behavior, American University, 4400 Massachusetts Ave, NW, Washington, DC 20016, USA.
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Alkhlaif Y, Shelton KL. Stimulus mediation, specificity and impact of menthol in rats trained to discriminate puffs of nicotine e-cigarette aerosol from nicotine-free aerosol. Psychopharmacology (Berl) 2024; 241:1527-1538. [PMID: 38519818 PMCID: PMC11269472 DOI: 10.1007/s00213-024-06579-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 03/15/2024] [Indexed: 03/25/2024]
Abstract
RATIONALE It is unclear if e-cigarettes have reduced abuse liability relative to traditional cigarettes, especially when considering advanced devices which deliver nicotine more efficiently. Translatable and predictive animal models are needed to addresses this question. OBJECTIVES Our goal was to explore the subjective stimulus effects of e-cigarettes by training rats to discriminate puffs of nicotine aerosol from vehicle aerosol using an aerosol delivery system designed to model e-cigarette use patterns in humans. METHODS Rats were trained to discriminate between ten, 10 s puffs of aerosol generated from 3 mg/ml nicotine e-liquid and nicotine-free e-liquid using a food-reinforced operant procedure. Following acquisition, tests were conducted to determine the specificity of the nicotine aerosol stimulus as well as the impact to the stimulus effects of nicotine resulting from the addition of menthol to e-liquid. RESULTS Rats learned the nicotine aerosol puff vs vehicle puff discrimination in a mean of 25 training sessions. Injected nicotine fully substituted for the stimulus effects of nicotine aerosol. The stimulus effects of nicotine aerosol were blocked by the nicotinic receptor antagonist mecamylamine. The nicotinic receptor partial agonist, varenicline as well as the stimulant d-amphetamine substituted more robustly for nicotine aerosol puffs than did the NMDA antagonist, ketamine. Menthol enhanced the stimulus effects of nicotine aerosol without altering nicotine blood plasma levels. CONCLUSIONS Nicotine aerosol puffs can function as a training stimulus in rats. The stimulus effects were CNS-mediated and receptor specific. Menthol appears to enhance the stimulus effects of nicotine aerosol through a pharmacodynamic rather than pharmacokinetic mechanism.
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Affiliation(s)
- Yasmin Alkhlaif
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, 410 North 12Th Street, Room 746D, Richmond, VA, 23298-0613, USA
| | - Keith L Shelton
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, 410 North 12Th Street, Room 746D, Richmond, VA, 23298-0613, USA.
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3
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Frankowska M, Wydra K, Suder A, Zaniewska M, Gawliński D, Miszkiel J, Furgała-Wojas A, Sałat K, Filip M, Müller CE, Kieć-Kononowicz K, Kotańska M. Novel GPR18 Ligands in Rodent Pharmacological Tests: Effects on Mood, Pain, and Eating Disorders. Int J Mol Sci 2023; 24:ijms24109046. [PMID: 37240392 DOI: 10.3390/ijms24109046] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/18/2023] [Accepted: 05/18/2023] [Indexed: 05/28/2023] Open
Abstract
The lack of selective pharmacological tools has limited the full unraveling of G protein-coupled receptor 18 (GPR18) functions. The present study was aimed at discovering the activities of three novel preferential or selective GPR18 ligands, one agonist (PSB-KK-1415) and two antagonists (PSB-CB-5 and PSB-CB-27). We investigated these ligands in several screening tests, considering the relationship between GPR18 and the cannabinoid (CB) receptor system, and the control of endoCB signaling over emotions, food intake, pain sensation, and thermoregulation. We also assessed whether the novel compounds could modulate the subjective effects evoked by Δ9-tetrahydrocannabinol (THC). Male mice or rats were pretreated with the GPR18 ligands, and locomotor activity, depression- and anxiety-like symptoms, pain threshold, core temperature, food intake, and THC-vehicle discrimination were measured. Our screening analyses indicated that GPR18 activation partly results in effects that are similar to those of CB receptor activation, considering the impact on emotional behavior, food intake, and pain activity. Thus, the orphan GPR18 may provide a novel therapeutic target for mood, pain, and/or eating disorders, and further investigation is warranted to better discern its function.
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Affiliation(s)
- Małgorzata Frankowska
- Department of Drug Addiction Pharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, Smętna 12 Street, 31-343 Kraków, Poland
| | - Karolina Wydra
- Department of Drug Addiction Pharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, Smętna 12 Street, 31-343 Kraków, Poland
| | - Agata Suder
- Department of Drug Addiction Pharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, Smętna 12 Street, 31-343 Kraków, Poland
| | - Magdalena Zaniewska
- Department of Drug Addiction Pharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, Smętna 12 Street, 31-343 Kraków, Poland
| | - Dawid Gawliński
- Department of Drug Addiction Pharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, Smętna 12 Street, 31-343 Kraków, Poland
| | - Joanna Miszkiel
- Department of Drug Addiction Pharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, Smętna 12 Street, 31-343 Kraków, Poland
| | - Anna Furgała-Wojas
- Chair of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9 Street, 30-688 Kraków, Poland
| | - Kinga Sałat
- Chair of Pharmacodynamics, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9 Street, 30-688 Kraków, Poland
| | - Małgorzata Filip
- Department of Drug Addiction Pharmacology, Maj Institute of Pharmacology Polish Academy of Sciences, Smętna 12 Street, 31-343 Kraków, Poland
| | - Christa E Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
| | - Katarzyna Kieć-Kononowicz
- Chair of Technology and Biotechnology of Drugs, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9 Street, 30-688 Kraków, Poland
| | - Magdalena Kotańska
- Department of Pharmacological Screening, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9 Street, 30-688 Kraków, Poland
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Perkins KA. Acute nicotine reinforcement requires ability to discriminate the stimulus effects of nicotine. Exp Clin Psychopharmacol 2022; 30:253-268. [PMID: 33119384 PMCID: PMC8406437 DOI: 10.1037/pha0000433] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This review of research on behavioral discrimination of nicotine and how it informs public health policy for reducing risk of tobacco dependence is adapted from Kenneth A. Perkins's American Psychological Association Division 28 (Psychopharmacology and Substance Abuse) 2020 Med Associates Brady/Schuster Award Lecture. The author's initial programmatic clinical research on nicotine is introduced, especially efforts to develop and validate a novel method of acute nicotine dosing. After the public health rationale for characterizing the discriminative stimulus effects of nicotine in humans are described, details from two separate programs of research on nicotine discrimination in humans are presented. The first, conducted with nicotine dosing by nasal spray, documented that humans could discriminate nicotine administered rapidly, examined nicotine's neuropharmacological specificity, identified discrimination threshold dose in smokers and nonsmokers, and explored other conditions that might alter ability to discriminate its effects. The second, more recent program focused on threshold doses for discrimination of nicotine by cigarette smoking, a program that was very difficult to do until the past decade, and how nicotine's self-reported "reward" and preference via choice behavior relate to its discriminability. Differences due to menthol and degree of tobacco dependence were also examined. For each of these two programs, the main findings of selected studies are noted, followed by very recent work on nicotine discrimination and choice that informs Food and Drug Administration's efforts to formulate public policy to improve health and reduce the nearly half million American deaths per year due to persistent tobacco use. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
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Stoops WW. A Brief Introduction to Human Behavioral Pharmacology: Methods, Design Considerations and Ethics. Perspect Behav Sci 2022; 45:361-381. [PMID: 35719875 PMCID: PMC9163231 DOI: 10.1007/s40614-022-00330-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2022] [Indexed: 11/25/2022] Open
Abstract
Human behavioral pharmacology methods have been used to rigorously evaluate the effects of a range of centrally acting drugs in humans under controlled conditions for decades. Methods like drug self-administration and drug discrimination have been adapted from nonhuman laboratory animal models. Because humans have the capacity to communicate verbally, self-report methods are also commonly used to understand drug effects. This perspective article provides an overview of these traditional human behavioral pharmacology methods and introduces some novel methodologies that have more recently been adapted for use in the field. Design (e.g., using placebo controls, testing multiple doses) and ethical (e.g., avoiding enrollment of individuals seeking treatment, determining capacity to consent) considerations that must be addressed when conducting these types of studies are also described.
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Affiliation(s)
- William W. Stoops
- University of Kentucky, 1100 Veterans Drive, Medical Behavioral Science Building Room 140, Lexington, KY 40536-0086 USA
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Palmer RK. Why Taste Is Pharmacology. Handb Exp Pharmacol 2022; 275:1-31. [PMID: 35461405 DOI: 10.1007/164_2022_589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The chapter presents an argument supporting the view that taste, defined as the receptor-mediated signaling of taste cells and consequent sensory events, is proper subject matter for the field of pharmacology. The argument develops through a consideration of how the field of pharmacology itself is to be defined. Though its application toward the discovery and development of therapeutics is of obvious value, pharmacology nevertheless is a basic science committed to examining biological phenomena controlled by the selective interactions between chemicals - regardless of their sources or uses - and receptors. The basic science of pharmacology is founded on the theory of receptor occupancy, detailed here in the context of taste. The discussion then will turn to consideration of the measurement of human taste and how well the results agree with the predictions of receptor theory.
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van den Berg M, Magaraggia I, Schreiber R, Hillhouse TM, Porter JH. How to account for hallucinations in the interpretation of the antidepressant effects of psychedelics: a translational framework. Psychopharmacology (Berl) 2022; 239:1853-1879. [PMID: 35348806 PMCID: PMC9166823 DOI: 10.1007/s00213-022-06106-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 02/24/2022] [Indexed: 01/02/2023]
Abstract
RATIONALE Recent trials with psychedelics in major depressive disorder and treatment-resistant depression showed remarkable improvements in depressive symptoms that can last for up to several months after even a single administration. The lack of an appropriate placebo control group-as patients are often able to discriminate the subjective effects of the drug-and an incomplete understanding of the role of the hallucinogenic and mystical experience, hampers the interpretation of these therapeutic effects. OBJECTIVES To control for these factors, we developed a translational framework based on establishing pharmacokinetic/pharmacodynamic (PK/PD) relationships in rodents and humans for hallucinogenic (i.e., discriminative stimulus effects in rodents and humans; head twitch responses in rodents; questionnaires in humans) and therapeutic effects. For the latter, we selected the pattern separation and attentional set-shifting tasks as measures for cognitive flexibility because of their high translational value. We predict that these PK/PD analyses will lead to a more objective evaluation of improvements in patients compared to relying only on the currently used self-reported questionnaires. We hypothesize that-if the role of the hallucinogenic experience is not central in the antidepressant effects of psychedelics-the ED50's for the therapeutic effects will be significantly lower than for the hallucinogenic and mystical effects. CONCLUSION Our framework will help to inform future studies that aim at the elucidation of the mechanism(s) of action of psychedelics in depression, and the role of the acute subjective and/or hallucinogenic experience in their effects.
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Affiliation(s)
- Manon van den Berg
- Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands ,Faculty of Psychology and Neuroscience, Section Neuropsychology & Psychopharmacology, Maastricht University, Maastricht, The Netherlands
| | - Igor Magaraggia
- Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands ,Faculty of Psychology and Neuroscience, Section Neuropsychology & Psychopharmacology, Maastricht University, Maastricht, The Netherlands
| | - Rudy Schreiber
- Faculty of Psychology and Neuroscience, Section Neuropsychology & Psychopharmacology, Maastricht University, Maastricht, The Netherlands.
| | - Todd M. Hillhouse
- Department of Psychology, University of Wisconsin Green Bay, Green Bay, WI USA
| | - Joseph H. Porter
- Department of Psychology, Virginia Commonwealth University, Richmond, USA
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Broadbear JH, Depoortere RY, Vacy K, Ralph D, Tunstall BJ, Newman-Tancredi A. Discriminative stimulus properties of the 5-HT1A receptor biased agonists NLX-101 and F13714, in rats trained to discriminate 8-OH-DPAT from saline. Behav Pharmacol 2021; 32:652-659. [PMID: 34751175 PMCID: PMC8589115 DOI: 10.1097/fbp.0000000000000659] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
NLX-101 and F13714 are selective, full efficacy, biased agonists of the serotonin (5-HT1A) receptor. NLX-101 preferentially activates cortical postsynaptic 5-HT1A receptors, whereas F13714 preferentially activates raphe nuclei presynaptic 5-HT1A receptors. We compared NLX-101 and F13714 for their efficacy and potency to substitute for the discriminative cue produced by the prototypical, nonbiased 5-HT1A receptor agonist 8-OH-DPAT (racemate). Male and female Sprague-Dawley rats were trained to discriminate 8-OH-DPAT (0.1 mg/kg i.p., 20 min pretreatment) from saline using a classical two-lever drug-discrimination procedure. 8-OH-DPAT (0.01 and 0.05 mg/kg i.p.) dose-dependently substituted for the training dose, with about 50% responding on the 8-OH-DPAT-associated lever at 0.05 mg/kg. F13714 fully and very potently substituted for the training dose of 8-OH-DPAT from 0.018 mg/kg i.p., whereas NLX-101 only achieved full substitution at 0.5 mg/kg i.p., a dose which is known to also activate presynaptic 5-HT1A receptors. The 5-HT1A receptor partial agonist, buspirone, partially substituted (~80%) at 1 and 2 mg/kg i.p., doses which also decreased response rates. F13714 decreased response rates at 0.05 mg/kg. The selective 5-HT1A receptor antagonist WAY-100 635 (1 mg/kg s.c., 40 min pretreatment) elicited almost no responding on the 8-OH-DPAT-associated lever by itself, but blocked the discriminative stimulus effects produced by administration (20 min pretreatment) of 8-OH-DPAT (0.1 mg/kg), F13714 (0.025 mg/kg), NLX-101 (0.5 mg/kg) or buspirone (1 mg/kg). These data suggest that the discriminative cue produced by 0.1 mg/kg i.p. 8-OH-DPAT results from activation of presynaptic 5-HT1A receptors. They also further demonstrate the distinct profiles in behavioral models of 5-HT1A receptor-biased agonists.
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Affiliation(s)
- Jillian H Broadbear
- Spectrum Personality Disorder Service, Richmond, Victoria, Australia
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | | | - Kristina Vacy
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
- The Florey Institute for Neuroscience and Mental Health, Parkville, Victoria, Australia
| | - David Ralph
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Brendan J Tunstall
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
- Department of Pharmacology, Addiction Science, and Toxicology, The University of Tennessee Health Science Center, Memphis, Tennessee, USA
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Hersey M, Bacon AK, Bailey LG, Coggiano MA, Newman AH, Leggio L, Tanda G. Psychostimulant Use Disorder, an Unmet Therapeutic Goal: Can Modafinil Narrow the Gap? Front Neurosci 2021; 15:656475. [PMID: 34121988 PMCID: PMC8187604 DOI: 10.3389/fnins.2021.656475] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/20/2021] [Indexed: 12/11/2022] Open
Abstract
The number of individuals affected by psychostimulant use disorder (PSUD) has increased rapidly over the last few decades resulting in economic, emotional, and physical burdens on our society. Further compounding this issue is the current lack of clinically approved medications to treat this disorder. The dopamine transporter (DAT) is a common target of psychostimulant actions related to their use and dependence, and the recent availability of atypical DAT inhibitors as a potential therapeutic option has garnered popularity in this research field. Modafinil (MOD), which is approved for clinical use for the treatment of narcolepsy and sleep disorders, blocks DAT just like commonly abused psychostimulants. However, preclinical and clinical studies have shown that it lacks the addictive properties (in both behavioral and neurochemical studies) associated with other abused DAT inhibitors. Clinical availability of MOD has facilitated its off-label use for several psychiatric disorders related to alteration of brain dopamine (DA) systems, including PSUD. In this review, we highlight clinical and preclinical research on MOD and its R-enantiomer, R-MOD, as potential medications for PSUD. Given the complexity of PSUD, we have also reported the effects of MOD on psychostimulant-induced appearance of several symptoms that could intensify the severity of the disease (i.e., sleep disorders and impairment of cognitive functions), besides the potential therapeutic effects of MOD on PSUD.
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Affiliation(s)
- Melinda Hersey
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Amanda K. Bacon
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Lydia G. Bailey
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Mark A. Coggiano
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Amy H. Newman
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Lorenzo Leggio
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
- Clinical Psychoneuroendo- crinology and Neuropsychopharmacology Section, Translational Addiction Medicine Branch, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
- National Institute on Alcohol Abuse and Alcoholism, Division of Intramural Clinical and Biological Research, National Institutes of Health, Bethesda, MD, United States
| | - Gianluigi Tanda
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
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Walentiny DM, Komla E, Moisa LT, Mustafa MA, Poklis JL, Akbarali HI, Beardsley PM. Methylnaltrexone crosses the blood-brain barrier and attenuates centrally-mediated behavioral effects of morphine and oxycodone in mice. Neuropharmacology 2020; 185:108437. [PMID: 33316279 DOI: 10.1016/j.neuropharm.2020.108437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/27/2020] [Accepted: 12/04/2020] [Indexed: 11/18/2022]
Abstract
BACKGROUND Antagonism of peripheral opioid receptors by methylnaltrexone (MNTX) was recently proposed as a potential mechanism to attenuate the development of opioid analgesic tolerance based on experiments conducted in mice. However, reports indicate that MNTX is demethylated to naltrexone (NTX) in mice, and NTX may subsequently cross the blood-brain barrier to antagonize centrally-mediated opioid effects. The goal of this study was to determine whether MNTX alters centrally-mediated behaviors elicited by the opioid analgesics, morphine and oxycodone, and to quantify concentrations of MNTX and NTX in blood and brain following their administration in mice. METHODS Combinations of MNTX and morphine were tested under acute and chronic conditions in thermal nociceptive assays. Effects of MNTX and NTX pretreatment were assessed in an oxycodone discrimination operant procedure. Blood and brain concentrations of these antagonists were quantified after their administration using liquid chromatography-mass spectrometry. RESULTS MNTX dose-dependently attenuated acute and chronic morphine antinociception. MNTX and NTX dose-dependently antagonized the discriminative stimulus effects of oxycodone. MNTX and NTX were detected in both blood and brain after administration of MNTX, confirming its demethylation and demonstrating that MNTX itself can cross the blood-brain barrier. CONCLUSIONS These results provide converging behavioral and analytical evidence that MNTX administration in mice attenuates centrally-mediated effects produced by opioid analgesics and results in functional concentrations of MNTX and NTX in blood and brain. Collectively, these findings indicate that MNTX cannot be administered systemically in mice for making inferences that its effects are peripherally restricted.
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Affiliation(s)
- D Matthew Walentiny
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA.
| | - Essie Komla
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA
| | - Léa T Moisa
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA
| | - Mohammed A Mustafa
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA
| | - Justin L Poklis
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA
| | - Hamid I Akbarali
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA
| | - Patrick M Beardsley
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, 1217 E. Marshall Street, Richmond, VA, 23298-0613, USA; Institute for Drug and Alcohol Studies & Center for Biomarker Research and Precision Medicine, Virginia Commonwealth University, 410 N. 12th Street, PO Box 980613, Richmond, VA, 23298-0613, USA
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11
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Popik P, Krawczyk M, Kuziak A, Bugno R, Hogendorf A, Staroń J, Nikiforuk A. Serotonin type 5A receptor antagonists inhibit D-lysergic acid diethylamide discriminatory cue in rats. J Psychopharmacol 2019; 33:1447-1455. [PMID: 31452444 DOI: 10.1177/0269881119867603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE Like other psychedelics, D-lysergic acid diethylamide (LSD) affects numerous serotonin receptors, and according to the current dogma, the 5-HT2A receptors are considered the main target for its hallucinogenic effects. LSD, however, also displays agonistic activity at the 5-HT5A receptors, which mediate some of LSD-induced behavioural effects. METHODS Using male Sprague Dawley rats, we examined the effects of 5-HT2A and 5-HT5A receptor antagonists on LSD-induced stimulus control in the two-lever drug discrimination test using a FR10 schedule of reinforcement. RESULTS In animals trained to discriminate 0.08 mg/kg LSD from vehicle 15 minutes after injection, LSD produced dose-related increases in response, with an ED50 (±95% confidence limits) of 0.0384 (± 0.025-0.051) mg/kg). LSD-like responses were observed when the training dose of LSD was given 5-30 but not 90 minutes before the test. Confirming earlier reports, the 5-HT antagonist ketanserin (2 mg/kg) attenuated the LSD response in 50% of rats, and due to pretreatment with 0.2 and 2 mg/kg MDL 100907, 63% and 67% of animals, respectively, failed to select the LSD lever. We then investigated the effects of two 5-HT5A receptor antagonists, and we found that 56% and 60% of rats pretreated with 3 and 10 mg/kg SB 699551, respectively, failed to select the LSD lever. Due to pretreatment with 0.01 mg/kg ASP 5736, 58% of rats did not select the LSD lever. This dose also reduced the response rate but not the number of rats failing to complete the test. CONCLUSIONS The present results suggest that antagonists of the 5-HT5A receptor may inhibit subjective effects of LSD in rats.
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Affiliation(s)
- Piotr Popik
- Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Martyna Krawczyk
- Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Agata Kuziak
- Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Ryszard Bugno
- Department of Medicinal Chemistry, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Adam Hogendorf
- Department of Medicinal Chemistry, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Jakub Staroń
- Department of Medicinal Chemistry, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Agnieszka Nikiforuk
- Behavioral Neuroscience and Drug Development, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
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Abstract
As investigators, we use many methodologies to answer both practical and theoretical questions in our field. Occasionally, we must stop and collect the latest findings or trends and then look forward to where our ideas, findings, and hypotheses may take us. Similar to volumes that were published in previous years on drug discrimination (Glennon and Young, Drug discrimination applications to medicinal chemistry and drug studies. Wiley, Hoboken, 2011; Ho et al., Drug discrimination and state dependent learning. Academic Press, New York, 1978), this collection in Current Topics in Behavioral Neurosciences serves as a current analysis of the continued value of the drug discrimination procedure to the fields of pharmacology, neuroscience, and psychology and as a stepping stone to where drug discrimination methodology can be applied next, in both a practical and theoretical sense. This final chapter represents one investigator's perspective on the utility and possibilities for a methodology that she fell in love with over 30 years ago.
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Affiliation(s)
- Ellen A Walker
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA, USA.
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