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Siemian JN, Woodhouse K, Liu DH, Zhang Y, Li JX. The imidazoline I 2 receptor agonist 2-BFI reduces abuse-related effects of morphine: self-administration and drug discrimination. Psychopharmacology (Berl) 2024; 241:479-487. [PMID: 38159161 DOI: 10.1007/s00213-023-06524-2] [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: 11/13/2023] [Accepted: 12/22/2023] [Indexed: 01/03/2024]
Abstract
RATIONALE Increasing evidence shows that imidazoline I2 receptor agonists enhance opioid-induced analgesia, suggesting that the combination of I2 receptor agonists with opioids could be a favorable strategy for pain control. However, the effect of I2 receptor agonists on the abuse liability of opioids is unknown. This study examined the impact of the I2 receptor agonist 2-BFI on some abuse-related behavioral effects of the opioid morphine in rats. OBJECTIVES The von Frey filament test was used to determine the antinociceptive effects of 2-BFI (intravenous, i.v.) in a rat model of complete Freund's adjuvant (CFA)-induced inflammatory pain. IV self-administration was used to assess the reinforcing effects of 2-BFI alone and to assess the effects of non-contingent injections of 2-BFI (i.p.) on morphine self-administration. A two-lever drug discrimination paradigm in which rats were trained to discriminate 3.2 mg/kg morphine (i.p.) from saline was used to examine whether 2-BFI or another I2 receptor agonist 2-(4,5-dihydroimidazol-2-yl)quinoline hydrochloride (BU224) affected the discriminative stimulus effects of morphine. RESULTS 2-BFI could not maintain reliable self-administration behavior in rats with no pain or CFA-treated inflammatory pain. However, pretreatment with 2-BFI (i.p.) produced dose-dependent decreases in the dose-effect curve of morphine self-administration. Both 2-BFI and BU224 did not substitute for morphine but significantly attenuated the discriminative stimulus effects of morphine. CONCLUSIONS These results suggest that I2 receptor agonists do not enhance, but in fact appear to decrease, the abuse liability of opioids, further supporting the potential utility of I2 receptor agonist-opioid combination therapy for pain control.
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Affiliation(s)
- Justin N Siemian
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Kristen Woodhouse
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | | | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, NC, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.
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Hernández-Hernández E, Ledesma-Corvi S, Yáñez-Gómez F, Garau C, Gálvez-Melero L, Bagán A, Escolano C, García-Fuster MJ. Sex differences in the antidepressant-like response and molecular events induced by the imidazoline-2 receptor agonist CR4056 in rats. Pharmacol Biochem Behav 2023; 223:173527. [PMID: 36781025 DOI: 10.1016/j.pbb.2023.173527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 02/08/2023] [Accepted: 02/08/2023] [Indexed: 02/13/2023]
Abstract
In searching for novel targets to design antidepressants, among the characterized imidazoline receptors (IR), I2 receptors are an innovative therapeutical approach since they are dysregulated in major depressive disorder and by classical antidepressant treatments. In fact, several I2 agonists have been characterized for their antidepressant-like potential, but the results in terms of efficacy were mixed and exclusively reported in male rodents. Since there are well-known sex differences in antidepressant-like efficacy, this study characterized the potential effects induced by two I2 drugs, CR4056 (i.e., most promising drug already in phase II clinical trial for its analgesic properties) and B06 (a compound from a new family of bicyclic α-iminophosphonates) under the stress of the forced-swim test in male and female rats exposed to early-life stress. Moreover, some hippocampal neuroplasticity markers related to the potential effects observed were also evaluated (i.e., FADD, p-ERK/ERK, mBDNF, cell proliferation: Ki-67 + cells). The main results replicated the only prior study reporting the efficacy of CR4056 in male rats, while providing new data on its efficacy in females, which was clearly dependent on prior early-life stress exposure. Moreover, B06 showed no antidepressant-like effects in male or female rats. Finally, CR4056 increased FADD content and decreased cell proliferation in hippocampus, without affecting p-ERK/t-ERK ratio and/or mBDNF content. Interestingly, these effects were exclusively observed in female rats, and independently of early-life conditions, suggesting some distinctive molecular underpinnings participating in the therapeutic response of CR4056 for both sexes. In conjunction, these results present CR4056 with an antidepressant-like potential, especially in female rats exposed to stress early in life, together with some neuronal correlates described in the context of these behavioral changes in females.
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Affiliation(s)
- Elena Hernández-Hernández
- IUNICS, University of the Balearic Islands, Palma, Spain; Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
| | - Sandra Ledesma-Corvi
- IUNICS, University of the Balearic Islands, Palma, Spain; Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
| | - Fernando Yáñez-Gómez
- IUNICS, University of the Balearic Islands, Palma, Spain; Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
| | - Celia Garau
- IUNICS, University of the Balearic Islands, Palma, Spain; Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
| | - Laura Gálvez-Melero
- IUNICS, University of the Balearic Islands, Palma, Spain; Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain
| | - Andrea Bagán
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
| | - Carmen Escolano
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
| | - M Julia García-Fuster
- IUNICS, University of the Balearic Islands, Palma, Spain; Health Research Institute of the Balearic Islands (IdISBa), Palma, Spain.
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Harris AC, Muelken P, LeSage MG. β-Carbolines found in cigarette smoke elevate intracranial self-stimulation thresholds in rats. Pharmacol Biochem Behav 2020; 198:173041. [PMID: 32926882 PMCID: PMC7554228 DOI: 10.1016/j.pbb.2020.173041] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/04/2020] [Accepted: 09/07/2020] [Indexed: 12/25/2022]
Abstract
Identifying novel constituents that contribute to tobacco addiction is essential for developing more effective treatments and informing FDA regulation of tobacco products. While preclinical data indicate that monoamine oxidase (MAO) inhibitors can have abuse liability or potentiate the addiction-related effects of nicotine, most of these studies have used clinical MAO inhibitors (e.g., tranylcypromine) that are not present in cigarette smoke. The primary goal of this study was to evaluate the abuse potential of the β-carbolines harmane, norharmane, and harmine - MAO inhibitors that are found in cigarette smoke - in an intracranial self-simulation (ICSS) model in rats. A secondary goal was to evaluate the ability of norharmane to influence nicotine's acute effects on ICSS. None of the β-carbolines lowered ICSS thresholds at any dose studied when administered alone, suggesting a lack of abuse liability. Rather, all three β-carbolines produced dose-dependent elevations in ICSS thresholds, indicating aversive/anhedonic effects. Harmane and harmine also elevated ICSS response latencies, suggesting a disruption of motor function, albeit with reduced potency compared to their ICSS threshold-elevating effects. Norharmane (2.5 mg/kg) modestly attenuated the effects of nicotine on ICSS thresholds. Our findings indicate that these β-carbolines produced only aversive/anhedonic effects in an ICSS model when administered alone, and that norharmane unexpectedly attenuated nicotines acute effects on ICSS. Future work evaluating the addiction-related effects of nicotine combined with these and other MAO inhibitors present in smoke may be useful for understanding the role of MAO inhibition in tobacco addiction and informing FDA tobacco regulation.
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Affiliation(s)
- Andrew C Harris
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States of America; Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, United States of America; Department of Psychology, University of Minnesota, Minneapolis, MN, United States of America.
| | - Peter Muelken
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States of America
| | - Mark G LeSage
- Hennepin Healthcare Research Institute, Minneapolis, MN, United States of America; Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, United States of America; Department of Psychology, University of Minnesota, Minneapolis, MN, United States of America
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Bousquet P, Hudson A, García-Sevilla JA, Li JX. Imidazoline Receptor System: The Past, the Present, and the Future. Pharmacol Rev 2020; 72:50-79. [PMID: 31819014 DOI: 10.1124/pr.118.016311] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Imidazoline receptors historically referred to a family of nonadrenergic binding sites that recognize compounds with an imidazoline moiety, although this has proven to be an oversimplification. For example, none of the proposed endogenous ligands for imidazoline receptors contain an imidazoline moiety but they are diverse in their chemical structure. Three receptor subtypes (I1, I2, and I3) have been proposed and the understanding of each has seen differing progress over the decades. I1 receptors partially mediate the central hypotensive effects of clonidine-like drugs. Moxonidine and rilmenidine have better therapeutic profiles (fewer side effects) than clonidine as antihypertensive drugs, thought to be due to their higher I1/α 2-adrenoceptor selectivity. Newer I1 receptor agonists such as LNP599 [3-chloro-2-methyl-phenyl)-(4-methyl-4,5-dihydro-3H-pyrrol-2-yl)-amine hydrochloride] have little to no activity on α 2-adrenoceptors and demonstrate promising therapeutic potential for hypertension and metabolic syndrome. I2 receptors associate with several distinct proteins, but the identities of these proteins remain elusive. I2 receptor agonists have demonstrated various centrally mediated effects including antinociception and neuroprotection. A new I2 receptor agonist, CR4056 [2-phenyl-6-(1H-imidazol-1yl) quinazoline], demonstrated clear analgesic activity in a recently completed phase II clinical trial and holds great promise as a novel I2 receptor-based first-in-class nonopioid analgesic. The understanding of I3 receptors is relatively limited. Existing data suggest that I3 receptors may represent a binding site at the Kir6.2-subtype ATP-sensitive potassium channels in pancreatic β-cells and may be involved in insulin secretion. Despite the elusive nature of their molecular identities, recent progress on drug discovery targeting imidazoline receptors (I1 and I2) demonstrates the exciting potential of these compounds to elicit neuroprotection and to treat various disorders such as hypertension, metabolic syndrome, and chronic pain.
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Affiliation(s)
- Pascal Bousquet
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
| | - Alan Hudson
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
| | - Jesús A García-Sevilla
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
| | - Jun-Xu Li
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
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5
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Vellani V, Sabatini C, Milia C, Caselli G, Lanza M, Letari O, Rovati LC, Giacomoni C. CR4056, a powerful analgesic imidazoline-2 receptor ligand, inhibits the inflammation-induced PKCε phosphorylation and membrane translocation in sensory neurons. Br J Pharmacol 2019; 177:48-64. [PMID: 31454418 DOI: 10.1111/bph.14845] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 08/10/2019] [Accepted: 08/12/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE CR4056 is a first-in-class imidazoline-2 (I2 ) receptor ligand characterized by potent analgesic activity in different experimental animal models of pain. In a recent phase II clinical trial, CR4056 effectively reduced pain in patients with knee osteoarthritis. In the present study, we investigated the effects of CR4056 on PKCε translocation in vitro and on PKCε activation in vivo in dorsal root ganglia (DRG) neurons. EXPERIMENTAL APPROACH Effects of CR4056 on bradykinin-induced PKCε translocation were studied in rat sensory neurons by immunocytochemistry. PKCε activation was investigated by immunohistochemistry analysis of DRG from complete Freund's adjuvant-treated animals developing local hyperalgesia. The analgesic activity of CR4056 was tested on the same animals. KEY RESULTS CR4056 inhibited PKCε translocation with very rapid and long-lasting activity. CR4056 decreased hyperalgesia and phospho-PKCε immunoreactivity in the DRG neurons innervating the inflamed paw. The effect of CR4056 on PKCε translocation was blocked by pertussis toxin, implying that the intracellular pathways involved Gi proteins. The inhibition of PKCε translocation by CR4056 was independent of the α2 -adrenoeceptor and, surprisingly, was also independent of idazoxan-sensitive I2 binding sites. The I2 agonist 2BFI had no effect alone but potentiated the activity of low concentrations of CR4056. CONCLUSIONS AND IMPLICATIONS Our results demonstrate that CR4056 shares the ability to inhibit PKCε translocation with other analgesics. Whether the inhibition of PKCε involves binding to specific subtype(s) of I2 receptors should be further investigated. If so, this would be a new mode of action of a highly specific I2 receptor ligand.
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Affiliation(s)
- Vittorio Vellani
- Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze, Università di Modena e Reggio Emilia, Modena, Italy
| | - Chiara Sabatini
- Rottapharm Biotech, Monza, Italy.,PhD Program in Neuroscience, Dipartimento di Medicina e chirurgia, Università degli Studi di Milano-Bicocca, Monza, Italy
| | - Chiara Milia
- PhD Program in Neuroscience, Dipartimento di Medicina e chirurgia, Università degli Studi di Milano-Bicocca, Monza, Italy
| | | | | | | | | | - Chiara Giacomoni
- Dipartimento di Economia, Scienze e Diritto, Università degli Studi della Repubblica di San Marino, San Marino
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6
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Siemian JN, Shang L, Seaman RW, Zhu Q, Zhang Y, Li JX. Effects of imidazoline I2 receptor agonists on reserpine-induced hyperalgesia and depressive-like behavior in rats. Behav Pharmacol 2019; 30:429-434. [PMID: 30383551 PMCID: PMC6494737 DOI: 10.1097/fbp.0000000000000454] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Pharmacotherapies for fibromyalgia treatment are lacking. This study examined the antinociceptive and antidepressant-like effects of imidazoline I2 receptor (I2R) agonists in a reserpine-induced model of fibromyalgia in rats. Rats were treated for 3 days with vehicle or reserpine. The von Frey filament test was used to assess the antinociceptive effects of I2 receptor agonists, and the forced swim test was used to assess the antidepressant-like effects of these drugs. 2-BFI (3.2-10 mg/kg, intraperitoneally), phenyzoline (17.8-56 mg/kg, intraperitoneally), and CR4056 (3.2-10 mg/kg, intraperitoneally) all dose-dependently produced significant antinociceptive effects, which were attenuated by the I2R antagonist idazoxan. Only CR4056 significantly reduced the immobility time in the forced swim test in both vehicle-treated and reserpine-treated rats. These data suggest that I2R agonists may be useful to treat fibromyalgia-related pain and comorbid depression.
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Affiliation(s)
- Justin N. Siemian
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
| | - Li Shang
- Department of Nursing, Affiliated Yantai Hospital of Binzhou Medical University, Yantai, Shandong, China
| | - Robert W. Seaman
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
| | - Qing Zhu
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
- School of Pharmacy, Nantong University, Nantong, Jiangsu, China
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, North Carolina, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
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7
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Liu JF, Seaman R, Siemian JN, Bhimani R, Johnson B, Zhang Y, Zhu Q, Hoener MC, Park J, Dietz DM, Li JX. Role of trace amine-associated receptor 1 in nicotine's behavioral and neurochemical effects. Neuropsychopharmacology 2018; 43:2435-2444. [PMID: 29472642 PMCID: PMC6180004 DOI: 10.1038/s41386-018-0017-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 01/18/2018] [Accepted: 01/20/2018] [Indexed: 12/21/2022]
Abstract
Nicotine addiction and abuse remains a global health issue. To date, the fundamental neurobiological mechanism of nicotine addiction remains incompletely understood. Trace amine-associated receptor 1 (TAAR1) is thought to directly modulate dopaminergic system and are thought to be a neural substrate underlying addictive-like behaviors. We aimed to investigate the role of TAAR1 in nicotine addictive-like behaviors. TAAR1 expression after nicotine treatment was evaluated by western blotting. c-Fos immunofluorescence and in vivo fast-scan cyclic voltammetry were used to examine the activation of brain regions and dopamine release, respectively. We then thoroughly and systematically examined the role of TAAR1 in mediating nicotine-induced sensitization, nicotine discrimination, nicotine self-administration, nicotine demand curve, and the reinstatement of nicotine-seeking. Local pharmacological manipulation was conducted to determine the role of TAAR1 in the nucleus accumbens (NAcs) in the reinstatement of nicotine-seeking. We found that the expression of TAAR1 protein was selectively downregulated in the NAc, with no change in either dorsal striatum or prefrontal cortex. TAAR1 activation was sufficient to block nicotine-induced c-Fos expression in the NAc, while also reducing nicotine-induced dopamine release in the NAc. Systemic administration of TAAR1 agonists attenuated the expression and development of nicotine-induced sensitization, nicotine self-administration, the reinstatement of nicotine-seeking, and increased the elasticity of nicotine demand curve, while intra-NAc infusions of a TAAR1 agonist was sufficient to attenuate nicotine reinstatement. Moreover, TAAR1-knockout rats showed augmented cue-induced and drug-induced reinstatement of nicotine-seeking. These results indicated that modulation of TAAR1 activity regulates nicotine addictive-like behaviors and TAAR1 represents a novel target towards the treatment of nicotine addiction.
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Affiliation(s)
- Jian-Feng Liu
- 0000 0004 1936 9887grid.273335.3Department of Pharmacology and Toxicology; Program in Neuroscience, University at Buffalo, Buffalo, NY 14214 USA ,0000 0000 9530 8833grid.260483.bSchool of Pharmacy, Nantong University, 226001 Nantong, China
| | - Robert Seaman
- 0000 0004 1936 9887grid.273335.3Department of Pharmacology and Toxicology; Program in Neuroscience, University at Buffalo, Buffalo, NY 14214 USA
| | - Justin N. Siemian
- 0000 0004 1936 9887grid.273335.3Department of Pharmacology and Toxicology; Program in Neuroscience, University at Buffalo, Buffalo, NY 14214 USA
| | - Rohan Bhimani
- 0000 0004 1936 9887grid.273335.3Department of Biotechnical and Clinical Laboratory Sciences, University at Buffalo, Buffalo, NY 14214 USA
| | - Bernard Johnson
- 0000 0004 1936 9887grid.273335.3Department of Pharmacology and Toxicology; Program in Neuroscience, University at Buffalo, Buffalo, NY 14214 USA
| | - Yanan Zhang
- 0000000100301493grid.62562.35Research Triangle Institute, Research Triangle Park, NC 27709 USA
| | - Qing Zhu
- 0000 0004 1936 9887grid.273335.3Department of Pharmacology and Toxicology; Program in Neuroscience, University at Buffalo, Buffalo, NY 14214 USA ,0000 0000 9530 8833grid.260483.bSchool of Pharmacy, Nantong University, 226001 Nantong, China
| | - Marius C. Hoener
- 0000 0004 0374 1269grid.417570.0Neuroscience, Ophthalmology and Rare Disease DTA, pRED, Roche Innovation Center Basel, F Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Jinwoo Park
- 0000 0004 1936 9887grid.273335.3Department of Biotechnical and Clinical Laboratory Sciences, University at Buffalo, Buffalo, NY 14214 USA
| | - David M. Dietz
- 0000 0004 1936 9887grid.273335.3Department of Pharmacology and Toxicology; Program in Neuroscience, University at Buffalo, Buffalo, NY 14214 USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology; Program in Neuroscience, University at Buffalo, Buffalo, NY, 14214, USA.
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8
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Siemian JN, Wang K, Zhang Y, Li JX. Mechanisms of imidazoline I 2 receptor agonist-induced antinociception in rats: involvement of monoaminergic neurotransmission. Br J Pharmacol 2018; 175:1519-1534. [PMID: 29451703 DOI: 10.1111/bph.14161] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Revised: 12/17/2017] [Accepted: 02/04/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND AND PURPOSE Although the antinociceptive efficacies of imidazoline I2 receptor agonists have been established, the exact post-receptor mechanisms remain unknown. This study tested the hypothesis that monoaminergic transmission is critical for I2 receptor agonist-induced antinociception. EXPERIMENTAL APPROACH von Frey filaments were used to assess antinociceptive effects of two I2 receptor agonists, 2-BFI and CR4056 on chronic constriction injury (CCI)-induced neuropathic pain or complete Freund's adjuvant (CFA)-induced inflammatory pain in rats. Rectal temperature was measured to assess hypothermic effects of 2-BFI. A two-lever drug discrimination paradigm in which rats were trained to discriminate 5.6 mg·kg-1 2-BFI (i.p.) from its vehicle was used to examine the discriminative stimulus effects of 2-BFI. In each experiment, pharmacological mechanisms were investigated by combining 2-BFI or CR4056 with various pharmacological manipulations of the monoaminergic system including selective reuptake inhibition, monoamine depletion and monoamine receptor antagonism. KEY RESULTS In the CCI model, selective reuptake inhibitors of 5-HT (fluoxetine) or noradrenaline (desipramine), but not dopamine (GBR12909), enhanced 2-BFI-induced antinociception. Selective depletion of 5-HT or noradrenaline almost abolished 2-BFI-induced antinociception. 5-HT1A , 5-HT2A and α1 -adrenoceptor antagonists, but not other monoaminergic antagonists, attenuated 2-BFI and CR4056-induced antinociception in CCI and/or CFA models. However, none of these monoamine receptor antagonists significantly altered 2-BFI-induced hypothermia or discriminative stimulus effects. CONCLUSIONS AND IMPLICATIONS Antinociception induced by I2 receptor agonists was mediated by serotonergic and noradrenergic mechanisms with 5-HT1A , 5-HT2A and α1 -adrenoceptor being particularly important. In contrast, the hypothermic and discriminative stimulus effects of I2 receptor agonists were mediated by distinct, independent mechanisms.
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Affiliation(s)
- Justin N Siemian
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY, USA
| | - Kaixuan Wang
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY, USA
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, NC, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, NY, USA.,School of Pharmacy, Yantai University, Yantai, Shandong Province, China
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Abstract
This paper is the thirty-ninth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2016 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and CUNY Neuroscience Collaborative, Queens College, City University of New York, Flushing, NY 11367, United States.
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10
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Fujiwara A, Shimosawa M, Iino M, Sasaki M, Sato SI, Shimoi A. Generalization tests using different dosing routes from those of drug discrimination training in rats. J Toxicol Sci 2018; 43:451-458. [DOI: 10.2131/jts.43.451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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11
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Role of intracellular Ca 2+ signaling in the antinociceptive and discriminative stimulus effects of the imidazoline I 2 receptor agonist 2-BFI in rats. Psychopharmacology (Berl) 2017; 234:3299-3307. [PMID: 28825118 PMCID: PMC5660937 DOI: 10.1007/s00213-017-4719-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/13/2017] [Indexed: 01/27/2023]
Abstract
RATIONALE Recent research has established the imidazoline I2 receptor as a promising target for the development of novel analgesics. However, despite an increasing understanding of imidazoline I2 receptor-mediated behavioral effects, little is known about post-I2-receptor signaling mechanisms. OBJECTIVE This study examined the effects of several inhibitors of Ca2+ signaling mechanisms on two behavioral effects of the prototypical imidazoline I2 receptor ligand 2-(2-benzofuranyl)-2-imidazoline (2-BFI). METHODS The von Frey filament test was used to examine the antinociceptive effects of 2-BFI in complete Freund's adjuvant (CFA)-induced inflammatory pain in rats. A two-lever drug discrimination paradigm in which rats were trained to discriminate 5.6 mg/kg (intraperitoneally) 2-BFI from its vehicle was used to examine the discriminative stimulus effects of 2-BFI. RESULTS The L-type Ca2+ channel blockers verapamil and nimodipine, the calmodulin antagonist W-7, and the internal Ca2+ release inhibitor ryanodine all attenuated the antinociceptive effects of 2-BFI. Oxycodone- and acetaminophen-induced antinociception was unaffected by pretreatment with the Ca2+ channel blockers. Rats learned to reliably discriminate 5.6 mg/kg 2-BFI from saline. The I2 receptor agonists BU224, RS45041, tracizoline, and CR4056 all fully substituted for 5.6 mg/kg 2-BFI while idazoxan, S22687, 2,5-dimethoxy-4-methylamphetamine (DOM), and phenyzoline produced partial or no substitution. Verapamil, nimodipine, and W-7 did not alter the discriminative stimulus effects of 2-BFI. CONCLUSION These results indicate that the antinociceptive effects of 2-BFI involve intracellular Ca2+ elevation and/or downstream Ca2+/calmodulin signaling, whereas the discriminative stimulus effects of 2-BFI are mediated by a distinct, independent mechanism.
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Abstract
Since first introduced more than two decades ago, the research in imidazoline I2 receptors has been steadily increasing. This review provides an update on the current status of I2 receptor pharmacology. Imidazoline I2 receptors or I2 binding sites refer to several (at least four) different proteins that bind to [3H]-idazoxan and [3H]-2-BFI with high affinity. The molecular identities of the proteins remain elusive. One of the proteins (45kD) seems to be consistent with the identity of brain creatine kinase. The biological functions of I2 receptors have been primarily unveiled by the studies of selective I2 receptor ligands. Accumulating evidence suggests that I2 receptor ligands are effective analgesics for persistent and chronic painful conditions such as inflammatory, neuropathic and postoperative pain. One selective I2 receptor ligand, CR4056, has been advanced to phase II clinical trial with the therapeutic indication of chronic inflammatory pain (osteoarthritis). The expansion to the treatment of other chronic pain conditions should be expected if CR4056 could eventually be approved as a new drug. I2 receptor ligands also demonstrate robust discriminative stimulus activity and induce a characteristic discriminative cue in animals. Biochemical and preclinical in vivo investigations also suggest that I2 receptor ligands have neuroprotective activity and modulate body temperature. The emerging discrepancies of a range of purported selective I2 receptor ligands suggest different pharmacological effects mediated by discrete I2 receptor components which likely attribute to the I2 receptor-related proteins. It is proposed that the I2 receptors represent an emerging drug target for the treatment of neurological disorders such as pain and stroke, and deserve more research attention to translate preclinical findings to pharmacotherapies.
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Affiliation(s)
- Jun-Xu Li
- School of Pharmacy, Nantong University, Nantong, Jiangsu Province, China; Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA.
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Ramsay RR. Molecular aspects of monoamine oxidase B. Prog Neuropsychopharmacol Biol Psychiatry 2016; 69:81-9. [PMID: 26891670 DOI: 10.1016/j.pnpbp.2016.02.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 02/06/2016] [Accepted: 02/11/2016] [Indexed: 02/07/2023]
Abstract
Monoamine oxidases (MAO) influence the monoamine levels in brain by virtue of their role in neurotransmitter breakdown. MAO B is the predominant form in glial cells and in platelets. MAO B structure, function and kinetics are described as a background for the effect of alterations in its activity on behavior. The need to inhibit MAO B to combat decreased brain amines continues to drive the search for new drugs. Reversible and irreversible inhibitors are now designed using data-mining, computational screening, docking and molecular dynamics. Multi-target ligands designed to combat the elevated activity of MAO B in Alzheimer's and Parkinson's Diseases incorporate MAO inhibition (usually irreversible) as well as iron chelation, antioxidant or neuroprotective properties. The main focus of drug design is the catalytic activity of MAO, but the imidazoline I2 site in the entrance cavity of MAO B is also a pharmacological target. Endogenous regulation of MAO B expression is discussed briefly in light of new studies measuring mRNA, protein, or activity in healthy and degenerative samples, including the effect of DNA methylation on the expression. Overall, this review focuses on examples of recent research on the molecular aspects of the expression, activity, and inhibition of MAO B.
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Affiliation(s)
- Rona R Ramsay
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews KY16 9ST, United Kingdom.
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14
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Thorn DA, Qiu Y, Zhang Y, Li JX. Antinociceptive effects of imidazoline I2 receptor agonists in the formalin test in rats. Behav Pharmacol 2016; 27:377-83. [PMID: 26599907 PMCID: PMC4842102 DOI: 10.1097/fbp.0000000000000206] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The imidazoline I2 receptor is an emerging drug target for analgesics. This study extended previous studies by examining the antinociceptive effects of three I2 receptor agonists (2-BFI, BU224, and CR4056) in the formalin test. The receptor mechanisms and anatomical mediation of I2 receptor agonist-induced antinociception were also examined. Formalin-induced flinching responses (2%, 50 μl) were quantified after treatment with I2 receptor agonists alone or in combination with the I2 receptor antagonist idazoxan. Anatomical mediation was studied by locally administering 2-BFI into the plantar surface or into the right lateral ventricle through cannulae (intracerebroventricular). The locomotor activity was also examined after central (intracerebroventricular) administration of 2-BFI. 2-BFI (1-10 mg/kg, intraperitoneal) and BU224 (1-10 mg/kg, intraperitoneal) attenuated the spontaneous flinching response observed during 10 min (phase 1) and 20-60 min (phase 2) following formalin treatment, whereas CR4056 (1-32 mg/kg, intraperitoneal) decreased only phase 2 flinching response. The I2 receptor antagonist idazoxan attenuated the antinociceptive effects of 2-BFI and BU224 during phase 1, but not phase 2. Peripheral administration of 2-BFI (1-10 mg/kg, intraplantar) to the hind paw of rats had no antinociceptive effect. In contrast, centrally delivered 2-BFI (10-100 µg, intracerebroventricular) dose-dependently attenuated phase 1 and phase 2 flinching at doses that did not reduce the locomotor activity. Together, these data revealed the differential antinociceptive effects of I2 receptor agonists and the differential antagonism profiles by idazoxan, suggesting the involvement of different I2 receptor subtypes in reducing different phases of formalin-induced pain-like behaviors. In addition, the results also suggest the central mediation of I2 receptor agonist-induced antinociceptive actions.
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Affiliation(s)
- David A Thorn
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
| | - Yanyan Qiu
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
| | - Yanan Zhang
- Research Triangle Institute, Research Triangle Park, North Caroline, USA
| | - Jun-Xu Li
- Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York, USA
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15
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Agmatine attenuates the discriminative stimulus and hyperthermic effects of methamphetamine in male rats. Behav Pharmacol 2016; 27:542-8. [PMID: 27232669 DOI: 10.1097/fbp.0000000000000244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Methamphetamine abuse remains an alarming public heath challenge, with no approved pharmacotherapies available. Agmatine is a naturally occurring cationic polyamine that has previously been shown to attenuate the rewarding and psychomotor-sensitizing effects of methamphetamine. This study examined the effects of agmatine on the discriminative stimulus and hyperthermic effects of methamphetamine. Adult male rats were trained to discriminate 0.32 mg/kg methamphetamine from saline. Methamphetamine dose dependently increased drug-associated lever responding. The nonselective dopamine receptor antagonist haloperidol (0.1 mg/kg) significantly attenuated the discriminative stimulus effects of methamphetamine (5.9-fold rightward shift). Agmatine (10-100 mg/kg) did not substitute for methamphetamine, but significantly attenuated the stimulus effects of methamphetamine, leading to a maximum of a 3.5-fold rightward shift. Acute 10 mg/kg methamphetamine increased the rectal temperature by a maximum of 1.96±0.17°C. Agmatine (10-32 mg/kg) pretreatment significantly attenuated the hyperthermic effect of methamphetamine. Agmatine (10 mg/kg) also significantly reversed methamphetamine-induced temperature increase. Together, these results support further exploration of the value that agmatine may have for the treatment of methamphetamine abuse and overdose.
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Anti-hyperalgesic effects of imidazoline I2 receptor ligands in a rat model of inflammatory pain: interactions with oxycodone. Psychopharmacology (Berl) 2015; 232:3309-18. [PMID: 26037946 PMCID: PMC4537836 DOI: 10.1007/s00213-015-3983-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 05/24/2015] [Indexed: 10/23/2022]
Abstract
RATIONALE Emerging preclinical evidence suggests that imidazoline I2 receptor ligands may be effective analgesics. Quantitative analysis of the combined I2 receptor ligands and opioids is needed for the justification of combination therapy. OBJECTIVE This study systematically examined the anti-hyperalgesic and response rate-suppressing effects of selective I2 receptor ligands (2-BFI and phenyzoline) alone and in combination with oxycodone in rats. METHODS Von Frey filament test was used to examine the anti-hyperalgesic effects of drugs in a rat model of complete Freund's adjuvant (CFA)-induced inflammatory pain. Schedule-controlled responding was used to assess the rate-altering effects of study drugs. Duration of actions of individual drugs (2-BFI, phenyzoline, and oxycodone) alone or in combination was studied. Dose-addition analysis was employed to assess the anti-hyperalgesic interactions between drugs. RESULTS Oxycodone (0.1-3.2 mg/kg, i.p.), 2-BFI (1-17.8 mg/kg, i.p.), and phenyzoline (17.8-56 mg/kg, i.p.) all dose-dependently produced significant antinociceptive effects. When studied as combinations, 2-BFI and oxycodone produced additive interactions while phenyzoline and oxycodone produced supra-additive interactions under all fixed ratios. The same drug combinations did not alter or significantly reduced the operant responding depending on the ratios of the drug combinations. CONCLUSIONS Quantitative analysis of the anti-hyperalgesic effects of I2 receptor ligands strongly supports the therapeutic potential of I2 receptor ligands against inflammatory pain. In addition, the data reveal that phenyzoline is superior to the prototypic I2 receptor ligand 2-BFI for the management of pain and warrants further consideration as a novel analgesic.
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Bektas N, Nemutlu D, Arslan R. The imidazoline receptors and ligands in pain modulation. Indian J Pharmacol 2015; 47:472-8. [PMID: 26600633 PMCID: PMC4621665 DOI: 10.4103/0253-7613.165196] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 04/22/2015] [Accepted: 08/09/2015] [Indexed: 11/11/2022] Open
Abstract
Pain is an unpleasant experience and effects daily routine negatively. Although there are various drugs, many of them are not entirely successful in relieving pain, since pain modulation is a complex process involving numerous mediators and receptors. Therefore, it is a rational approach to identify the factors involved in the complex process and develop new agents that act on these pain producing mechanisms. In this respect, the involvement of the imidazoline receptors in pain modulation has drawn attention in recent years. In this review, it is aimed to focus on the imidazoline receptors and their ligands which contribute to the pain modulation. It is demonstrated that imidazoline-2 (I2) receptors are steady new drug targets for analgesics. Even if the mechanism of I2 receptor is not well known in the modulation of pain, it is known that it plays a role in tonic and chronic pain but not in acute phasic pain. Moreover, the I2 receptor ligands increase the analgesic effects of opioids in both acute and chronic pain and prevent the development of opioid tolerance. So, they are valuable for the chronic pain treatment and also therapeutic coadjuvants in the management of chronic pain with opiate drugs due to the attenuation of opioid tolerance and addiction. Thus, the use of the ligands which bind to the imidazoline receptors is an effective strategy for relieving pain. This educational forum exhibits the role of imidazoline receptors and ligands in pain process by utilizing experimental studies.
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Affiliation(s)
- Nurcan Bektas
- Department of Pharmacology, Faculty of Pharmacy, Anadolu University, Eskisehir 26470, Turkey
| | - Dilara Nemutlu
- Department of Pharmacology, Faculty of Pharmacy, Anadolu University, Eskisehir 26470, Turkey
| | - Rana Arslan
- Department of Pharmacology, Faculty of Pharmacy, Anadolu University, Eskisehir 26470, Turkey
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