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Jiménez-Altayó F, Cabrera A, Bagán A, Giménez-Llort L, D’Ocon P, Pérez B, Pallàs M, Escolano C. An Imidazoline 2 Receptor Ligand Relaxes Mouse Aorta via Off-Target Mechanisms Resistant to Aging. Front Pharmacol 2022; 13:826837. [PMID: 35645795 PMCID: PMC9133327 DOI: 10.3389/fphar.2022.826837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
Imidazoline receptors (IR) are classified into three receptor subtypes (I1R, I2R, and I3R) and previous studies showed that regulation of I2R signaling has neuroprotective potential. In order to know if I2R has a role in modulating vascular tone in health and disease, we evaluated the putative vasoactive effects of two recently synthesized I2R ligands, diethyl (1RS,3aSR,6aSR)-5-(3-chloro-4-fluorophenyl)-4,6-dioxo-1-phenyl-1,3a,4,5,6,6a-hexahydropyrrolo[3,4-c]pyrrole -1-phosphonate (B06) and diethyl [(1-(3-chloro-4-fluorobenzyl)-5,5-dimethyl-4-phenyl-4,5-dihydro-1H-imidazol-4-yl]phosphonate] (MCR5). Thoracic aortas from Oncins France 1 (3- to 4-months-old) and C57BL/6 (3- to 4- and 16- to 17-months-old mice) were mounted in tissue baths to measure isometric tension. In young mice of both strains, MCR5 induced greater relaxations than either B06 or the high-affinity I2R selective ligand 2-(2-benzofuranyl)-2-imidazoline (2-BFI), which evoked marginal responses. MCR5 relaxations were independent of I2R, as IR ligands did not significantly affect them, involved activation of smooth muscle KATP channels and inhibition of L-type voltage-gated Ca2+ channels, and were only slightly modulated by endothelium-derived nitric oxide (negatively) and prostacyclin (positively). Notably, despite the presence of endothelial dysfunction in old mice, MCR5 relaxations were preserved. In conclusion, the present study provides evidence against a functional contribution of I2R in the modulation of vascular tone in the mouse aorta. Moreover, the I2R ligand MCR5 is an endothelium-independent vasodilator that acts largely via I2R-independent pathways and is resistant to aging. We propose MCR5 as a candidate drug for the management of vascular disease in the elderly.
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Affiliation(s)
- Francesc Jiménez-Altayó
- Department of Pharmacology, Therapeutics and Toxicology, School of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
- *Correspondence: Francesc Jiménez-Altayó,
| | - Anna Cabrera
- Department of Pharmacology, Therapeutics and Toxicology, School of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Andrea Bagán
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
| | - Lydia Giménez-Llort
- Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
- Department of Psychiatry and Forensic Medicine, School of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Pilar D’Ocon
- Department of Pharmacology, School of Medicine, Universidad de Valencia, Burjassot, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universidad de Valencia, Valencia, Spain
| | - Belén Pérez
- Department of Pharmacology, Therapeutics and Toxicology, School of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain
- Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Mercè Pallàs
- Pharmacology Section, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, Institut de Neurociències, 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, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
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2
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Vasilopoulou F, Escolano C, Pallàs M, Griñán-Ferré C. Microarray Analysis Revealed Inflammatory Transcriptomic Changes after LSL60101 Treatment in 5XFAD Mice Model. Genes (Basel) 2021; 12:genes12091315. [PMID: 34573297 PMCID: PMC8468036 DOI: 10.3390/genes12091315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/20/2021] [Accepted: 08/23/2021] [Indexed: 12/23/2022] Open
Abstract
I2-IR have been found dysregulated in patients with neurodegenerative diseases, such as Alzheimer’s disease (AD), in which the importance of neuroinflammation in the establishment and maintenance of cognitive decline is well-documented. To research the implication of I2-IR in neuroinflammatory pathways altered in AD, we determined the expression profile of genes associated with inflammation in the 5XFAD model treated with LSL60101, a well-established I2-IR ligand. Thus, we performed a qPCR array containing 84 inflammation-related genes. Hierarchical clustering analysis revealed three gene clusters, suggesting that treatment with LSL60101 affects the gene expression associated with inflammation in the 5XFAD model. Furthermore, we evaluated the functions of the three clusters; thereby performing a pathway enrichment analysis using the GO database. As we expected, clusters 2 and 3 showed alterations in the inflammatory response, chemotaxis and the chemokine-mediated signaling pathway, among others. To validate previous results from the gene profiling analysis, the expression levels of a representative subset of mRNAs were selected according to the intensity of the observed changes and their biological relevance. Interestingly, changes induced by LSL60101 in the 5XFAD model were validated for several genes. These results suggest that treatment with LSL60101 in the 5XFAD model reverses the inflammatory process during the development of AD.
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Affiliation(s)
- Foteini Vasilopoulou
- Pharmacology Section, Department of Pharmacology, Toxicology and Therapeutic Chemistry, Faculty of Pharmacy and Food Sciences, Institute of Neuroscience, University of Barcelona (NeuroUB), Av. Joan XXIII 27-31, 08028 Barcelona, Spain; (F.V.); (M.P.)
| | - Carmen Escolano
- Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Department of Pharmacology, Toxicology and Medicinal Chemistry, Faculty of Pharmacy and Food Sciences, Institute of Biomedicine (IBUB), University of Barcelona, Av. Joan XXIII, 27-31, 08028 Barcelona, Spain;
| | - Mercè Pallàs
- Pharmacology Section, Department of Pharmacology, Toxicology and Therapeutic Chemistry, Faculty of Pharmacy and Food Sciences, Institute of Neuroscience, University of Barcelona (NeuroUB), Av. Joan XXIII 27-31, 08028 Barcelona, Spain; (F.V.); (M.P.)
| | - Christian Griñán-Ferré
- Pharmacology Section, Department of Pharmacology, Toxicology and Therapeutic Chemistry, Faculty of Pharmacy and Food Sciences, Institute of Neuroscience, University of Barcelona (NeuroUB), Av. Joan XXIII 27-31, 08028 Barcelona, Spain; (F.V.); (M.P.)
- Correspondence:
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3
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Hsu JCN, Sekizawa S, Tochinai R, Kuwahara M. Loss of Group II Metabotropic Glutamate Receptor Signaling Exacerbates Hypertension in Spontaneously Hypertensive Rats. Life (Basel) 2021; 11:life11070720. [PMID: 34357092 PMCID: PMC8307370 DOI: 10.3390/life11070720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/13/2021] [Accepted: 07/18/2021] [Indexed: 11/16/2022] Open
Abstract
High blood pressure is a major risk factor of cerebro-cardiovascular outcomes. Blood pressure is partly regulated by the autonomic nervous system and its reflex functions; therefore, we hypothesized that pharmacological intervention in the brainstem that can regulate blood pressure could be a novel therapeutic strategy to control hypertension. We infused a group II metabotropic glutamate receptor (mGluR) antagonist (LY341495, 0.40 μg/day), using a mini-osmotic pump, into the dorsal medulla oblongata in young spontaneously hypertensive rats (SHRs), as this area is adjacent to the nucleus tractus solitarius (NTS), of which the neurons are involved in baroreflex pathways with glutamatergic transmission. Blood pressure was recorded for conscious rats with the tail cuff method. A 6-week antagonist treatment from 6 to 12 weeks of age slightly but significantly increased systolic blood pressure by >30 mmHg, compared to that in SHRs without treatment. Moreover, the effect continued even 3 weeks after the treatment ended, and concurred with an increase in blood catecholamine concentration. However, heart rate variability analysis revealed that LY341495 treatment had little effect on autonomic activity. Meanwhile, mRNA expression level of mGluR subtype 2, but not subtype 3 in the brainstem was significantly enhanced by the antagonist treatment in SHRs, possibly compensating the lack of mGluR signaling. In conclusion, mGluR2 signaling in the dorsal brainstem is crucial for preventing the worsening of hypertension over a relatively long period in SHRs, through a mechanism of catecholamine secretion. This may be a specific drug target for hypertension therapy.
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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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Djikic T, Vucicevic J, Laurila J, Radi M, Veljkovic N, Xhaard H, Nikolic K. Deciphering Imidazoline Off‐targets by Fishing in the Class A of GPCR field. Mol Inform 2020; 39:e1900165. [DOI: 10.1002/minf.201900165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 02/20/2020] [Indexed: 12/13/2022]
Affiliation(s)
- Teodora Djikic
- Department of Pharmaceutical ChemistryFaculty of PharmacyUniversity of Belgrade Vojvode Stepe 450 11000 Belgrade Serbia
| | - Jelica Vucicevic
- Department of Pharmaceutical ChemistryFaculty of PharmacyUniversity of Belgrade Vojvode Stepe 450 11000 Belgrade Serbia
| | - Jonne Laurila
- Research Center for Integrative Physiology and Pharmacology, Institute of BiomedicineUniversity of Turku FI-20014 Turun yliopisto, Turku Finland
| | - Marco Radi
- Dipartimento di Scienze degli Alimenti e del FarmacoUniversità degli Studi di Parma Viale delle Scienze, 27/A 43124 Parma Italy
| | - Nevena Veljkovic
- Laboratory for bioinformatics and computational chemistry, Institute of Nuclear Sciences VincaUniversity of Belgrade Mihaila Petrovica Alasa 14 11001 Belgrade Serbia
| | - Henri Xhaard
- Division of Pharmaceutical Chemistry, Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of PharmacyUniversity of Helsinki P.O. Box 56 FI-00014 Helsinki Finland
| | - Katarina Nikolic
- Department of Pharmaceutical ChemistryFaculty of PharmacyUniversity of Belgrade Vojvode Stepe 450 11000 Belgrade Serbia
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Spay C, Albares M, Lio G, Thobois S, Broussolle E, Lau B, Ballanger B, Boulinguez P. Clonidine modulates the activity of the subthalamic-supplementary motor loop: evidence from a pharmacological study combining deep brain stimulation and electroencephalography recordings in Parkinsonian patients. J Neurochem 2019; 146:333-347. [PMID: 29675956 DOI: 10.1111/jnc.14447] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/15/2018] [Accepted: 04/04/2018] [Indexed: 12/24/2022]
Abstract
Clonidine is an anti-hypertensive medication which acts as an alpha-adrenergic receptor agonist. As the noradrenergic system is likely to support cognitive functions including attention and executive control, other clinical uses of clonidine have recently gained popularity for the treatment of neuropsychiatric disorders like attention-deficit hyperactivity disorder or Tourette syndrome, but the mechanism of action is still unclear. Here, we test the hypothesis that the noradrenergic system regulates the activity of subthalamo-motor cortical loops, and that this influence can be modulated by clonidine. We used pharmacological manipulation of clonidine in a placebo-controlled study in combination with subthalamic nucleus-deep brain stimulation (STN-DBS) in 16 Parkinson's disease patients performing a reaction time task requiring to refrain from reacting (proactive inhibition). We recorded electroencephalographical activity of the whole cortex, and applied spectral analyses directly at the source level after advanced blind source separation. We found only one cortical source localized to the supplementary motor area (SMA) that supported an interaction of pharmacological and subthalamic stimulation. Under placebo, STN-DBS reduced proactive alpha power in the SMA, a marker of local inhibitory activity. This effect was associated with the speeding-up of movement initiation. Clonidine substantially increased proactive alpha power from the SMA source, and canceled out the benefits of STN-DBS on movement initiation. These results provide the first direct neural evidence in humans that the tonic inhibitory activity of the subthalamocortical loops underlying the control of movement initiation is coupled to the noradrenergic system, and that this activity can be targeted by pharmacological agents acting on alpha-adrenergic receptors.
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Affiliation(s)
- Charlotte Spay
- Université de Lyon, Lyon, France.,Université Lyon 1, Villeurbanne, France.,INSERM, U 1028, Lyon Neuroscience Research Center, Lyon, France.,CNRS, UMR 5292, Lyon Neuroscience Research Center, Lyon, France
| | - Marion Albares
- Université de Lyon, Lyon, France.,Université Lyon 1, Villeurbanne, France.,CNRS, UMR 5229, Institut des Sciences Cognitives Marc Jeannerod, Bron, France.,Sorbonne Universités, UPMC Université Pierre et Marie Curie Paris 06, UMR 7225, Paris, France.,INSERM UMR 1127, Institut du cerveau et de la moelle épinière, ICM, Paris, France.,CNRS, UMR 7225, Institut du cerveau et de la moelle épinière, ICM, Paris, France
| | - Guillaume Lio
- Université de Lyon, Lyon, France.,Université Lyon 1, Villeurbanne, France.,CNRS, UMR 5229, Institut des Sciences Cognitives Marc Jeannerod, Bron, France
| | - Stephane Thobois
- Université de Lyon, Lyon, France.,Université Lyon 1, Villeurbanne, France.,CNRS, UMR 5229, Institut des Sciences Cognitives Marc Jeannerod, Bron, France.,Hospices civils de Lyon, hôpital neurologique Pierre Wertheimer, Bron, France
| | - Emmanuel Broussolle
- Université de Lyon, Lyon, France.,Université Lyon 1, Villeurbanne, France.,CNRS, UMR 5229, Institut des Sciences Cognitives Marc Jeannerod, Bron, France.,Hospices civils de Lyon, hôpital neurologique Pierre Wertheimer, Bron, France
| | - Brian Lau
- Sorbonne Universités, UPMC Université Pierre et Marie Curie Paris 06, UMR 7225, Paris, France.,INSERM UMR 1127, Institut du cerveau et de la moelle épinière, ICM, Paris, France.,CNRS, UMR 7225, Institut du cerveau et de la moelle épinière, ICM, Paris, France
| | - Benedicte Ballanger
- Université de Lyon, Lyon, France.,Université Lyon 1, Villeurbanne, France.,INSERM, U 1028, Lyon Neuroscience Research Center, Lyon, France.,CNRS, UMR 5292, Lyon Neuroscience Research Center, Lyon, France
| | - Philippe Boulinguez
- Université de Lyon, Lyon, France.,Université Lyon 1, Villeurbanne, France.,INSERM, U 1028, Lyon Neuroscience Research Center, Lyon, France.,CNRS, UMR 5292, Lyon Neuroscience Research Center, Lyon, France
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7
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Kitano T, Kobayashi T, Yamaguchi S, Otsuguro KI. The α 2A -adrenoceptor subtype plays a key role in the analgesic and sedative effects of xylazine. J Vet Pharmacol Ther 2018; 42:243-247. [PMID: 30417462 DOI: 10.1111/jvp.12724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 09/04/2018] [Accepted: 09/05/2018] [Indexed: 11/27/2022]
Abstract
Xylazine, the classical α2 -adrenoceptor (α2 -AR) agonist, is still used as an analgesic and sedative in veterinary medicine, despite its low potency and affinity for α2 -ARs. Previous pharmacological studies suggested that the α2A -AR subtype plays a role in mediating the clinical effects of xylazine; however, these studies were hampered by the poor subtype-selectivity of the antagonists used and a lack of knowledge of their bioavailability in vivo. Here, we attempted to elucidate the role of the α2A -AR subtype in mediating the clinical effects of xylazine by comparing the analgesic and sedative effects of this drug in wild-type mice with those in α2A -AR functional knockout mice using the hot-plate and open field tests, respectively. Hippocampal noradrenaline turnover in both mice was also measured to evaluate the contribution of α2A -AR subtype to the inhibitory effect of xylazine on presynaptic noradrenaline release. In wild-type mice, xylazine (10 or 30 mg/kg) increased the hot-plate latency. Furthermore, xylazine (3 or 10 mg/kg) inhibited the open field locomotor activity and decreased hippocampal noradrenaline turnover. By contrast, all of these effects were abolished in α2A -AR functional knockout mice. These results indicate that the α2A -AR subtype is mainly responsible for the clinical effects of xylazine.
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Affiliation(s)
- Taisuke Kitano
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Takeshi Kobayashi
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Soichiro Yamaguchi
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Ken-Ichi Otsuguro
- Laboratory of Pharmacology, Department of Basic Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
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Weiss T, Bernard R, Bernstein HG, Veh RW, Laube G. Agmatine modulates spontaneous activity in neurons of the rat medial habenular complex-a relevant mechanism in the pathophysiology and treatment of depression? Transl Psychiatry 2018; 8:201. [PMID: 30250120 PMCID: PMC6155246 DOI: 10.1038/s41398-018-0254-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/02/2018] [Accepted: 08/17/2018] [Indexed: 12/15/2022] Open
Abstract
The dorsal diencephalic conduction system connects limbic forebrain structures to monaminergic mesencephalic nuclei via a distinct relay station, the habenular complexes. Both habenular nuclei, the lateral as well as the medial nucleus, are considered to play a prominent role in mental disorders like major depression. Herein, we investigate the effect of the polyamine agmatine on the electrical activity of neurons within the medial habenula in rat. We present evidence that agmatine strongly decreases spontaneous action potential firing of medial habenular neurons by activating I1-type imidazoline receptors. Additionally, we compare the expression patterns of agmatinase, an enzyme capable of inactivating agmatine, in rat and human habenula. In the medial habenula of both species, agmatinase is similarly distributed and observed in neurons and, in particular, in distinct neuropil areas. The putative relevance of these findings in the context of depression is discussed. It is concluded that increased activity of the agmatinergic system in the medial habenula may strengthen midbrain dopaminergic activity. Consequently, the habenular-interpeduncular axis may be dysregulated in patients with major depression.
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Affiliation(s)
- Torsten Weiss
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Vegetative Anatomy, Berlin, Germany.
| | - René Bernard
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Klinik für Neurologie, Department of Experimental Neurology, Berlin, Germany
| | - Hans-Gert Bernstein
- 0000 0001 1018 4307grid.5807.aDepartment of Psychiatry and Psychotherapy, Medical Faculty, University of Magdeburg, Magdeburg, Germany
| | - Rüdiger W. Veh
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Vegetative Anatomy, Berlin, Germany
| | - Gregor Laube
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Vegetative Anatomy, Berlin, Germany
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9
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Matsui K, Ozawa M, Kiso M, Yamashita M, Maekawa T, Kubota M, Sugano S, Kawaoka Y. Stimulation of alpha2-adrenergic receptors impairs influenza virus infection. Sci Rep 2018; 8:4631. [PMID: 29545586 PMCID: PMC5854622 DOI: 10.1038/s41598-018-22927-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 02/26/2018] [Indexed: 11/30/2022] Open
Abstract
Influenza A viruses cause seasonal epidemics and occasional pandemics. The emergence of viruses resistant to neuraminidase (NA) inhibitors and M2 ion channel inhibitors underlines the need for alternate anti-influenza drugs with novel mechanisms of action. Here, we report the discovery of a host factor as a potential target of anti-influenza drugs. By using cell-based virus replication screening of a chemical library and several additional assays, we identified clonidine as a new anti-influenza agent in vitro. We found that clonidine, which is an agonist of the alpha2-adrenergic receptor (α2-AR), has an inhibitory effect on the replication of various influenza virus strains. α2-AR is a Gi-type G protein-coupled receptor that reduces intracellular cyclic AMP (cAMP) levels. In-depth analysis showed that stimulation of α2-ARs leads to impairment of influenza virus replication and that α2-AR agonists inhibit the virus assembly step, likely via a cAMP-mediated pathway. Although clonidine administration did not reduce lung virus titers or prevent body weight loss, it did suppress lung edema and improve survival in a murine lethal infection model. Clonidine may thus protect against lung damage caused by influenza virus infection. Our results identify α2-AR-mediated signaling as a key pathway to exploit in the development of anti-influenza agents.
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Affiliation(s)
- Ken Matsui
- Laboratory of Next Generation Drug Development, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa-shi, Chiba, Japan.,Pharmaceutical and Healthcare Research Laboratories, Research and Development Management Headquarters, Fujifilm Corporation, Kaisei-machi, Ashigarakami-gun, Kanagawa, Japan
| | - Makoto Ozawa
- Laboratory of Animal Hygiene, Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima-shi, Kagoshima, Japan
| | - Maki Kiso
- Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Makoto Yamashita
- Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Toshihiko Maekawa
- Laboratory of Next Generation Drug Development, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa-shi, Chiba, Japan.,Pharmaceutical and Healthcare Research Laboratories, Research and Development Management Headquarters, Fujifilm Corporation, Kaisei-machi, Ashigarakami-gun, Kanagawa, Japan
| | - Minoru Kubota
- Laboratory of Next Generation Drug Development, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa-shi, Chiba, Japan.,Pharmaceutical and Healthcare Research Laboratories, Research and Development Management Headquarters, Fujifilm Corporation, Kaisei-machi, Ashigarakami-gun, Kanagawa, Japan
| | - Sumio Sugano
- Laboratory of Next Generation Drug Development, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa-shi, Chiba, Japan.,Laboratory of Functional Genomics, Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Yoshihiro Kawaoka
- Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan. .,International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan. .,Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA. .,Exploratory Research for Advanced Technology Infection-Induced Host Responses Project, Japan Science and Technology Agency, Saitama, Japan.
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10
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Sandweiss AJ, Morrison CM, Spichler A, Rozich J. A case report of clonidine induced syncope: a review of central actions of an old cardiovascular drug. BMC Pharmacol Toxicol 2018; 19:6. [PMID: 29433586 PMCID: PMC5810118 DOI: 10.1186/s40360-018-0198-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 02/07/2018] [Indexed: 01/22/2023] Open
Abstract
Background Clonidine is an imidazoline sympatholytic, acting on both α2-adrenergic and imidazoline receptors in the brainstem to induce antihypertensive and negative chronotropic effects in the vasculature and heart respectively. Case presentation A 69-year-old gentleman with hypertension presented to the emergency department after multiple syncopal episodes over the past 12 months. Electrocardiogram demonstrated sinus bradycardia with a heart rate of 42 beats per minute. It was hypothesized that the antihypertensive agent clonidine was responsible for inducing symptomatic bradycardia. Clonidine was thus gradually tapered and then discontinued over five days restoring normal sinus rhythm rates while avoiding hypertensive rebound related to sympathetic surge. His heart rate and blood pressure remained within normal limits after the clonidine taper and subsequent adjustments to his other hypertensive medications and he was discharged. Conclusions While clonidine has fallen out of favor for its indication as an antihypertensive, it remains a viable option for the use of opioid withdrawal, chronic pain, and smoking cessation, necessitating the appropriate clinical and pharmacological competencies for a physician to prescribe. A discussion of the clinical effects of clonidine brainstem receptor activation follows.
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Affiliation(s)
- Alexander J Sandweiss
- University of Arizona, Department of Pharmacology, College of Medicine, 1501 N. Campbell Ave LSN 621, Tucson, AZ, 85724, USA.
| | | | - Anne Spichler
- University of Arizona, Department of Medicine, College of Medicine, Tucson, AZ, USA
| | - John Rozich
- Southern Arizona Veterans Affairs Health Care System, Tucson, AZ, USA
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11
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Wittenberg-Voges L, Kästner SB, Raekallio M, Vainio OM, Rohn K, Hopster K. Effect of dexmedetomidine and xylazine followed by MK-467 on gastrointestinal microperfusion in anaesthetized horses. Vet Anaesth Analg 2017; 45:165-174. [PMID: 29439859 DOI: 10.1016/j.vaa.2017.08.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 06/15/2017] [Accepted: 08/21/2017] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To compare the effects of MK-467 during isoflurane anaesthesia combined with xylazine or dexmedetomidine on global and gastrointestinal perfusion parameters. STUDY DESIGN Prospective, randomized experimental trial. ANIMALS A total of 15 warmblood horses. METHODS Horses were divided into two groups for administration of either dexmedetomidine (D) or xylazine (X) for premedication (D: 3.5 μg kg-1; X: 0.5 mg kg-1) and as constant rate infusion during isoflurane anaesthesia (D: 7 μg kg-1 hour-1; X: 1 mg kg-1 hour-1). During anaesthesia, heart rate, mean arterial blood pressure (MAP), systemic vascular resistance index (SVRI) and cardiac index (CI) were measured. Microperfusion of the colon, jejunum and stomach was measured using laser Doppler flowmetry. After 2 hours of stabilization, MK-467 (250 μg kg-1) was administered, and measurements were continued for another 90 minutes. For statistical analysis, the permutation test and Wilcoxon rank-sum test were used (p < 0.05). RESULTS There were no differences in baseline measurements between groups. The MK-467 bolus resulted in a significant decrease in MAP (D: -58%; X: -48%) and SVRI (D: -68%; X: -65%) lasting longer in group D (90 minutes) compared to group X (60 minutes). While CI increased (D: +31%; X: +35%), microperfusion was reduced in the colon (D: -44%; X: -34%), jejunum (D: -26%; X: -33%) and stomach (D: -37%; X: -35%). CONCLUSIONS AND CLINICAL RELEVANCE Alpha-2-agonist induced vasoconstriction was reversed by the MK-467 dose used, resulting in hypotension and rise in CI. Gastrointestinal microperfusion decreased, probably as a result of insufficient perfusion pressure. An infusion rate for MK-467 as well as an ideal agonist/antagonist ratio should be determined.
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Affiliation(s)
| | - Sabine Br Kästner
- Clinic for Horses, University of Veterinary Medicine Hannover, Hanover, Germany
| | - Marja Raekallio
- University of Helsinki, Faculty of Veterinary Medicine, Helsinki, Finland
| | - Outi M Vainio
- University of Helsinki, Faculty of Veterinary Medicine, Helsinki, Finland
| | - Karl Rohn
- Department of Biometry, University of Veterinary Medicine Hannover, Hanover, Germany
| | - Klaus Hopster
- Clinic for Horses, University of Veterinary Medicine Hannover, Hanover, Germany
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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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13
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Schmeling WT, Farber NE. The Effects of α2-Adrenergic Agonists on the Cardiovascular System. Semin Cardiothorac Vasc Anesth 2016. [DOI: 10.1177/108925329700100209] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- William T. Schmeling
- Departments of Anesthesiology, Pharmacology & Toxicology, The Medical College of Wisconsin, Children's Hospital of Wisconsin, and The Zablocki Veterans Affairs Medical Center, Milwaukee, WI
| | - Neil E. Farber
- Departments of Anesthesiology, Pharmacology & Toxicology, The Medical College of Wisconsin, Children's Hospital of Wisconsin, and The Zablocki Veterans Affairs Medical Center, Milwaukee, WI
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14
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Abstract
Children/adolescents with attention-deficit/hyperactivity disorder (ADHD) may have a poor or inadequate response to psychostimulants or be unable to tolerate their side-effects; furthermore, stimulants may be inappropriate because of co-existing conditions. Only one non-stimulant ADHD pharmacotherapy, the noradrenaline transporter inhibitor atomoxetine, is currently approved for use in Europe. We review recent advances in understanding of the pathophysiology of ADHD with a focus on the roles of catecholamine receptors in context of the α2A-adrenergic receptor agonist guanfacine extended release (GXR), a new non-stimulant treatment option in Europe. Neuroimaging studies of children/adolescents with ADHD show impaired brain maturation, and structural and functional anomalies in brain regions and networks. Neurobiological studies in ADHD and medication response patterns support involvement of monoaminergic neurotransmitters (primarily dopamine and noradrenaline). Guanfacine is a selective α2A-adrenergic receptor agonist that has been shown to improve prefrontal cortical cognitive function, including working memory. The hypothesized mode of action of guanfacine centres on direct stimulation of post-synaptic α2A-adrenergic receptors to enhance noradrenaline neurotransmission. Preclinical data suggest that guanfacine also influences dendritic spine growth and maturation. Clinical trials have demonstrated the efficacy of GXR in ADHD, and it is approved as monotherapy or adjunctive therapy to stimulants in Canada and the USA (for children and adolescents). GXR was approved recently in Europe for the treatment of ADHD in children and adolescents for whom stimulants are not suitable, not tolerated or have been shown to be ineffective. GXR may provide particular benefit for children/adolescents who have specific co-morbidities such as chronic tic disorders or oppositional defiant disorder (or oppositional symptoms) that have failed to respond to first-line treatment options.
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15
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Lim K, van den Buuse M, Head GA. Effect of Endothelin-1 on Baroreflexes and the Cardiovascular Action of Clonidine in Conscious Rabbits. Front Physiol 2016; 7:321. [PMID: 27516742 PMCID: PMC4963462 DOI: 10.3389/fphys.2016.00321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 07/13/2016] [Indexed: 12/20/2022] Open
Abstract
We studied the influence of pretreatment with endothelin–1 on cardiac baroreflexes and on the effect of clonidine on blood pressure and heart rate. In order to avoid the complication of the direct vasoconstrictor effects of endothelin-1, initial dose-response studies in animals treated with a ganglion blocker were performed. Intravenous administration of 50, 200, and 1200 ng/kg of endothelin-1 produced biphasic changes in blood pressure, consisting of an immediate depressor response, followed by a long lasting and dose-dependent pressor effect (peak response 3 ± 1, 9 ± 3, and 33 ± 5 mmHg, respectively). Thus, the 50 ng/kg dose of endothelin-1 was used in subsequent studies. Conscious rabbits were pretreated on separate days with endothelin-1, either intravenously (50 ng/kg) or intracisternally (10 and 50 ng/kg), or with vehicle. The animals then received an intravenous dose (20 μg/kg) or an intracisternal dose (1 μg/kg) of clonidine and the effects on blood pressure and heart rate were measured. In vehicle-treated rabbits, the intravenous administration of clonidine induced a significant decrease in blood pressure and heart rate (15 min after injection: −15.7 ± 4.7 mmHg and −33 ± 4 b/min, respectively). Similarly, the intracisternal injection of clonidine lowered blood pressure (−16.0 ± 2.5 mmHg), but produced a less pronounced bradycardia (−18 ± 4 b/min). Endothelin pretreatment, either 50 ng/kg centrally or peripherally, had no significant effect on the hypotension or bradycardia produced either by central or peripheral injection of clonidine. At this dose, endothelin by itself did not produce significant changes in blood pressure or heart rate. There was a reduction of the gain of the baroreceptor-heart rate reflex with intracisternal endothelin-1. These results suggest that central 2–adrenoceptor mechanisms involved in clonidine-induced hypotension and bradycardia do not appear to be influenced by activation of endothelin receptors.
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Affiliation(s)
- Kyungjoon Lim
- Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Research Institute Melbourne, VIC, Australia
| | - Maarten van den Buuse
- School of Psychology and Public Health, La Trobe UniversityMelbourne, VIC, Australia; Department of Pharmacology, University of MelbourneMelbourne, VIC, Australia
| | - Geoffrey A Head
- Neuropharmacology Laboratory, Baker IDI Heart and Diabetes Research InstituteMelbourne, VIC, Australia; Department of Pharmacology, Monash UniversityClayton, VIC, Australia
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16
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Wu X, Pang G, Zhang YM, Li G, Xu S, Dong L, Stackman RW, Zhang G. Activation of serotonin 5-HT(2C) receptor suppresses behavioral sensitization and naloxone-precipitated withdrawal symptoms in heroin-treated mice. Neurosci Lett 2015; 607:23-28. [PMID: 26375926 DOI: 10.1016/j.neulet.2015.09.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 09/09/2015] [Accepted: 09/10/2015] [Indexed: 11/20/2022]
Abstract
Abuse and dependence to heroin has evolved into a global epidemic as a significant clinical and societal problem with devastating consequences. Repeated exposure to heroin can induce long-lasting behavioral sensitization and withdrawal. Pharmacological activation of 5-HT2C receptors (5-HT2CRs) suppresses psychostimulant-induced drug-seeking and behavioral sensitization. The present study examined the effect of a selective 5-HT2CR agonist lorcaserin on behavioral sensitization and naloxone-precipitated withdrawal symptoms in heroin-treated mice. Male mice received heroin (1.0 mg/kg, s.c.) twice a day for 3 days and then drug treatment was suspended for 5 days. On day 9, a challenge dose of heroin (1.0 mg/kg) was administered to examine the expression of behavioral sensitization. Lorcaserin administered during the development, withdrawal or expression stage suppressed heroin-induced behavioral sensitization on day 9. Another cohort of mice received increasing doses of heroin over a 4.5-day period. Lorcaserin, or the positive control clonidine (an α2-adrenoceptor agonist) suppressed naloxone-precipitated withdrawal symptoms in heroin-treated mice. These findings suggest that activation of 5-HT2CRs suppresses behavioral sensitization and withdrawal in heroin-treated mice. Thus, pharmacological activation of 5-HT2CRs may represent a new avenue for the treatment of heroin addiction.
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Affiliation(s)
- Xian Wu
- College of Basic Medicine, Anhui Medical University, 81 Meishan Road, Hefei, Anhui 230032, China
| | - Gang Pang
- College of Basic Medicine, Anhui Medical University, 81 Meishan Road, Hefei, Anhui 230032, China
| | - Yong-Mei Zhang
- Jiangsu Province Key Laboratory of Anesthesiology; College of Anesthesiology, Xuzhou Medical College, Xuzhou, Jiangsu 221002, China
| | - Guangwu Li
- College of Basic Medicine, Anhui Medical University, 81 Meishan Road, Hefei, Anhui 230032, China
| | - Shengchun Xu
- College of Basic Medicine, Anhui Medical University, 81 Meishan Road, Hefei, Anhui 230032, China
| | - Liuyi Dong
- College of Basic Medicine, Anhui Medical University, 81 Meishan Road, Hefei, Anhui 230032, China
| | - Robert W Stackman
- Department of Psychology, Florida Atlantic University and the Life Science Initiative at FAU, 5353 Parkside Drive, Jupiter, FL 33458, USA
| | - Gongliang Zhang
- College of Basic Medicine, Anhui Medical University, 81 Meishan Road, Hefei, Anhui 230032, China
- Department of Psychology, Florida Atlantic University and the Life Science Initiative at FAU, 5353 Parkside Drive, Jupiter, FL 33458, USA
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17
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Ostock CY, Hallmark J, Palumbo N, Bhide N, Conti M, George JA, Bishop C. Modulation of L-DOPA's antiparkinsonian and dyskinetic effects by α2-noradrenergic receptors within the locus coeruleus. Neuropharmacology 2015; 95:215-25. [PMID: 25817388 DOI: 10.1016/j.neuropharm.2015.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/12/2015] [Accepted: 03/09/2015] [Indexed: 01/01/2023]
Abstract
Long-term l-DOPA use for Parkinson's disease (PD) is frequently complicated by the emergence of a debilitating motor side effect known as l-DOPA-induced dyskinesia (LID). Accumulating evidence has implicated the norepinephrine (NE) system in the pathogenesis of LID. Here we used the unilateral 6-hydroxydopamine rat model of PD to determine the role of the α2-adrenoceptors (α2R) in l-DOPA's therapeutic and detrimental motor-inducing effects. First, we characterized the effects of systemic α2R stimulation with clonidine, or blockade with atipamezole, on LID using the rodent abnormal involuntary movements scale, and l-DOPA's therapeutic effects using the forepaw adjusting steps test and locomotor activity chambers. The anatomical locus of action of α2R in LID was investigated by directly infusing clonidine or atipamezole into the locus coeruleus prior to systemic l-DOPA administration. Results showed systemic clonidine treatment reduced LID and locomotor activity but did not interfere with l-DOPA's antiparkinsonian benefits. Conversely, systemic atipamezole pretreatment prolonged LID and locomotor activity but did not modulate l-DOPA's antiparkinsonian benefits. Intra-LC infusions of clonidine and atipamezole mirrored systemic effects where clonidine reduced, and atipamezole increased, LID. Collectively, these results demonstrate that α2R play an important modulatory role in l-DOPA-mediated behaviors and should be further investigated as a potential therapeutic target.
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Affiliation(s)
- Corinne Y Ostock
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Joy Hallmark
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Noel Palumbo
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Nirmal Bhide
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Melissa Conti
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Jessica A George
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA
| | - Christopher Bishop
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY, USA.
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18
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Qiu Y, Zhang Y, Li JX. Discriminative stimulus effects of the imidazoline I2 receptor ligands BU224 and phenyzoline in rats. Eur J Pharmacol 2015; 749:133-41. [PMID: 25617792 DOI: 10.1016/j.ejphar.2015.01.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 01/09/2015] [Accepted: 01/14/2015] [Indexed: 01/25/2023]
Abstract
Although imidazoline I2 receptor ligands have been used as discriminative stimuli, the role of efficacy of I2 receptor ligands as a critical determinant in drug discrimination has not been explored. This study characterized the discriminative stimulus effects of selective imidazoline I2 receptor ligands BU224 (a low-efficacy I2 receptor ligand) and phenyzoline (a higher efficacy I2 receptor ligand) in rats. Two groups of male Sprague-Dawley rats were trained to discriminate 5.6mg/kg BU224 or 32mg/kg phenyzoline (i.p.) from their vehicle in a two-lever food-reinforced drug discrimination procedure, respectively. All rats acquired the discriminations after an average of 18 (BU224) and 56 (phenyzoline) training sessions, respectively. BU224 and phenyzoline completely substituted for one another symmetrically. Several I2 receptor ligands (tracizoline, CR4056, RS45041, and idazoxan) all occasioned>80% drug-associated lever responding in both discriminations. The I2 receptor ligand 2-BFI and a monoamine oxidase inhibitor harmane occasioned>80% drug-associated lever responding in rats discriminating BU224. Other drugs that occasioned partial or less substitution to BU224 cue included clonidine, methamphetamine, ketamine, morphine, methadone and agmatine. Clonidine, methamphetamine and morphine also only produced partial substitution to phenyzoline cue. Naltrexone, dopamine D2 receptor antagonist haloperidol and serotonin (5-HT)2A receptor antagonist MDL100907 failed to alter the discriminative stimulus effects of BU224 or phenyzoline. Combined, these results are the first to demonstrate that BU224 and phenyzoline can serve as discriminative stimuli and that the low-efficacy I2 receptor ligand BU224 shares similar discriminative stimulus effects with higher-efficacy I2 receptor ligands such as phenyzoline and 2-BFI.
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Affiliation(s)
- Yanyan Qiu
- 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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19
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McLean LS, Crane L, Baziard-Mouysset G, Edwards LP. Antiproliferative effect induced by novel imidazoline S43126 in PC12 cells is mediated by ROS, stress activated MAPKs and caspases. Pharmacol Rep 2014; 66:937-45. [DOI: 10.1016/j.pharep.2014.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 06/04/2014] [Accepted: 06/05/2014] [Indexed: 11/25/2022]
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20
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Baptista JFDA, Gomez RS, Paulo DNS, Carraretto AR, Brocco MC, Silva JJ. Epidural anesthesia with ropivacaine with or without clonidine and postoperative pain in hemorrhoidectomies. Acta Cir Bras 2014; 29:201-8. [PMID: 24626733 DOI: 10.1590/s0102-86502014000300009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 02/19/2014] [Indexed: 11/22/2022] Open
Abstract
PURPOSE To determine the safety, pain intensity correlated with age and body mass index (BMI), epidural anesthesia with ropivacaine and clonidine in hemorrhoidectomy. METHODS Eighty patients, both genders, 20-70 years old, ASA I or II, for hemorrhoidectomy were randomly divided into two groups: Control (n=38), epidural anesthesia with 14 mL of ropivacaine 0.75 % plus 0.0266 mL/kg of 0.9% saline solution; Experimental (n=42) epidural anesthesia with 14 mL of 0.75% ropivacaine plus 4.0 mcg/kg of clonidine. In preoperative and postoperative period were evaluated: systolic blood pressure (SBP), diastolic blood pressure (DBP ), heart rate (HR ), pulse oximetry (SpO2), electrocardiography (ECG), pain intensity (VAS ) in four, eight and, 12 hours and analgesic consumption. RESULTS The VAS values differed between four, eight and 12 hours in the Experimental Group, where correlation of VAS 12h with age (p<0.05) occurred and not with BMI and more patients (p<0.05) did not receive analgesics. SBP, DBP, HR changed similarly in both groups at 15, 30 and 45 min. The ECG and SpO2 remained unchanged. CONCLUSIONS Clonidine (4mcg/kg) in epidural anesthesia with ropivacaine 0.75% in hemorrhoidectomy showed safety and greater analgesia within four hours. The pain at 12 hours showed correlation with age and not with body mass index.
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Affiliation(s)
- João Florêncio de Abreu Baptista
- Espirito Santo Federal University, Department of Surgical Clinic, VitoriaES, Brazil, Master, Fellow PhD degree, Postgraduate Program in Ophthalmological Surgical and Applied Sciences, Minas Gerais Federal University (UFMG). Associate professor, Division of Anesthesiology, Department of Surgical Clinic, Espirito Santo Federal University (UFES), Vitoria-ES, Brazil. Conception, design and scientific content of the study
| | - Renato Santiago Gomez
- UFMG, Department of Surgery, Minas Gerais, Brazil, Associate Professor, Division of Anesthesiology, Department of Surgery, UFMG, Minas Gerais, Brazil. Conception and scientific content of the study
| | - Danilo Nagib Salomão Paulo
- EMESCAM, College of Health Sciences, Department of Surgery, VitoriaES, Brazil, Full Professor, Department of Surgery, College of Health Sciences, EMESCAM, Vitoria-ES, Brazil. Critical revision
| | - Antonio Roberto Carraretto
- Espirito Santo Federal University, Department of Surgery, VitoriaES, Brazil, IVPhD, Associate Professor, Division of Anesthesiology, Department of Surgery, Espirito Santo Federal University (UFES), Vitoria-ES, Brazil. Manuscript writing, critical revision
| | - Marcos Celio Brocco
- UFES, Department of Surgical Clinic, VitoriaES, Brazil, VPhD, Associate Professor, Division of Anesthesiology, Department of Surgical Clinic, UFES, Vitoria-ES, Brazil. Statistical analysis, critical revision
| | - José Jorge Silva
- UFES, Department of Surgical, VitoriaES, Brazil, Master, Assistant Professor, Division of Surgery, Department of Surgery, UFES, Vitoria-ES Brazil. Statistical analysis, critical revision
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Mohamed Shenger MS, Filipic S, Nikolic K, Agbaba D. ESTIMATION OF LIPOPHILICITY AND RETENTION BEHAVIOR OF SOME ALPHA ADRENERGIC AND IMIDAZOLINE RECEPTOR LIGANDS USING RP-TLC. J LIQ CHROMATOGR R T 2014. [DOI: 10.1080/10739149.2014.906880] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
| | - Slavica Filipic
- a Department of Pharmaceutical Chemistry, Faculty of Pharmacy , University of Belgrade , Belgrade , Serbia
| | - Katarina Nikolic
- a Department of Pharmaceutical Chemistry, Faculty of Pharmacy , University of Belgrade , Belgrade , Serbia
| | - Danica Agbaba
- a Department of Pharmaceutical Chemistry, Faculty of Pharmacy , University of Belgrade , Belgrade , Serbia
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Neuber C, Uebeler J, Schulze T, Sotoud H, El-Armouche A, Eschenhagen T. Guanabenz interferes with ER stress and exerts protective effects in cardiac myocytes. PLoS One 2014; 9:e98893. [PMID: 24892553 PMCID: PMC4044035 DOI: 10.1371/journal.pone.0098893] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 05/08/2014] [Indexed: 12/11/2022] Open
Abstract
Endoplasmic reticulum (ER) stress has been implicated in a variety of cardiovascular diseases. During ER stress, disruption of the complex of protein phosphatase 1 regulatory subunit 15A and catalytic subunit of protein phosphatase 1 by the small molecule guanabenz (antihypertensive, α2-adrenoceptor agonist) and subsequent inhibition of stress-induced dephosphorylation of eukaryotic translation initiation factor 2α (eIF2α) results in prolonged eIF2α phosphorylation, inhibition of protein synthesis and protection from ER stress. In this study we assessed whether guanabenz protects against ER stress in cardiac myocytes and affects the function of 3 dimensional engineered heart tissue (EHT). We utilized neonatal rat cardiac myocytes for the assessment of cell viability and activation of ER stress-signalling pathways and EHT for functional analysis. (i) Tunicamycin induced ER stress as measured by increased mRNA and protein levels of glucose-regulated protein 78 kDa, P-eIF2α, activating transcription factor 4, C/EBP homologous protein, and cell death. (ii) Guanabenz had no measurable effect alone, but antagonized the effects of tunicamycin on ER stress markers. (iii) Tunicamycin and other known inducers of ER stress (hydrogen peroxide, doxorubicin, thapsigargin) induced cardiac myocyte death, and this was antagonized by guanabenz in a concentration- and time-dependent manner. (iv) ER stressors also induced acute or delayed contractile dysfunction in spontaneously beating EHTs and this was, with the notable exception of relaxation deficits under thapsigargin, not significantly affected by guanabenz. The data confirm that guanabenz interferes with ER stress-signalling and has protective effects on cell survival. Data show for the first time that this concept extends to cardiac myocytes. The modest protection in EHTs points to more complex mechanisms of force regulation in intact functional heart muscle.
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Affiliation(s)
- Christiane Neuber
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- DZHK (German Center for Cardiovascular Research), partner site, Hamburg/Kiel/Luebeck, Germany
| | - June Uebeler
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- DZHK (German Center for Cardiovascular Research), partner site, Hamburg/Kiel/Luebeck, Germany
| | - Thomas Schulze
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- DZHK (German Center for Cardiovascular Research), partner site, Hamburg/Kiel/Luebeck, Germany
| | - Hannieh Sotoud
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- DZHK (German Center for Cardiovascular Research), partner site, Hamburg/Kiel/Luebeck, Germany
| | - Ali El-Armouche
- Department of Pharmacology, University Medical Center Goettingen, Goettingen, Germany
- DZHK (German Center for Cardiovascular Research), partner site Goettingen, Germany
- Department of Pharmacology, University of Technology Dresden, Dresden, Germany
| | - Thomas Eschenhagen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- DZHK (German Center for Cardiovascular Research), partner site, Hamburg/Kiel/Luebeck, Germany
- * E-mail:
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23
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Abstract
Heart failure (HF), the leading cause of death in the western world, develops when a cardiac injury or insult impairs the ability of the heart to pump blood and maintain tissue perfusion. It is characterized by a complex interplay of several neurohormonal mechanisms that become activated in the syndrome to try and sustain cardiac output in the face of decompensating function. Perhaps the most prominent among these neurohormonal mechanisms is the adrenergic (or sympathetic) nervous system (ANS), whose activity and outflow are enormously elevated in HF. Acutely, and if the heart works properly, this activation of the ANS will promptly restore cardiac function. However, if the cardiac insult persists over time, chances are the ANS will not be able to maintain cardiac function, the heart will progress into a state of chronic decompensated HF, and the hyperactive ANS will continue to push the heart to work at a level much higher than the cardiac muscle can handle. From that point on, ANS hyperactivity becomes a major problem in HF, conferring significant toxicity to the failing heart and markedly increasing its morbidity and mortality. The present review discusses the role of the ANS in cardiac physiology and in HF pathophysiology, the mechanisms of regulation of ANS activity and how they go awry in chronic HF, methods of measuring ANS activity in HF, the molecular alterations in heart physiology that occur in HF, along with their pharmacological and therapeutic implications, and, finally, drugs and other therapeutic modalities used in HF treatment that target or affect the ANS and its effects on the failing heart.
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Affiliation(s)
- Anastasios Lymperopoulos
- Department of Pharmaceutical Sciences, Nova Southeastern University College of Pharmacy, Ft. Lauderdale, FL 33328-2018, USA.
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Fellmann L, Regnault V, Greney H, Gasparik V, Muscat A, Max JP, Gigou L, Oréa V, Chetrite G, Pizard A, Niederhoffer N, Julien C, Lacolley P, Fève B, Bousquet P. A New Pyrroline Compound Selective for I1-Imidazoline Receptors Improves Metabolic Syndrome in Rats. J Pharmacol Exp Ther 2013; 346:370-80. [DOI: 10.1124/jpet.113.205328] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Abstract
α2 adrenergic receptor (α2-AR) agonists have been used as antihypertensive agents, in the management of drug withdrawal, and as sedative analgesics. Since α2-AR agonists also influence the regulation of body temperature, we explored their potential as antipyretic agents. This study delineates the central neural substrate for the inhibition of rat brown adipose tissue (BAT) and shivering thermogenesis by α2-AR agonists. Nanoinjection of the α2-AR agonist clonidine (1.2 nmol) into the rostral raphe pallidus area (rRPa) inhibited BAT sympathetic nerve activity (SNA) and BAT thermogenesis. Subsequent nanoinjection of the α2-AR antagonist idazoxan (6 nmol) into the rRPa reversed the clonidine-evoked inhibition of BAT SNA and BAT thermogenesis. Systemic administration of the α2-AR agonists dexmedetomidine (25 μg/kg, i.v.) and clonidine (100 μg/kg, i.v.) inhibited shivering EMGs, BAT SNA, and BAT thermogenesis, effects that were reversed by nanoinjection of idazoxan (6 nmol) into the rRPa. Dexmedetomidine (100 μg/kg, i.p.) prevented and reversed lipopolysaccharide-evoked (10 μg/kg, i.p.) thermogenesis in free-behaving rats. Cholera toxin subunit b retrograde tracing from rRPa and pseudorabies virus transynaptic retrograde tracing from BAT combined with immunohistochemistry for catecholaminergic biosynthetic enzymes revealed the ventrolateral medulla as the source of catecholaminergic input to the rRPa and demonstrated that these catecholaminergic neurons are synaptically connected to BAT. Photostimulation of ventrolateral medulla neurons expressing the PRSx8-ChR2-mCherry lentiviral vector inhibited BAT SNA via activation of α2-ARs in the rRPa. These results indicate a potent inhibition of BAT and shivering thermogenesis by α2-AR activation in the rRPa, and suggest a therapeutic potential of α2-AR agonists for reducing potentially lethal elevations in body temperature during excessive fever.
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Abstract
Clonidine, an α(2)-adrenergic agonist, is approved in the US as an extended-release (XR) tablet for the treatment of attention-deficit hyperactivity disorder (ADHD) in children and adolescents (aged 6-17 years). In two, randomized, double-blind, multicenter, phase III trials of 8 weeks' duration, clonidine XR improved the symptoms of ADHD in children and adolescents. Significantly greater reductions from baseline in ADHD rating scale IV (ADHD-RS-IV) total scores at week 5 (primary endpoint) were achieved by recipients of clonidine XR 0.2 and 0.4 mg/day monotherapy than by recipients of placebo. When added to patients' normal stimulant regimen, significantly greater reductions from baseline in ADHD-RS-IV total scores at week 5 (primary endpoint) were achieved with a flexible dose of clonidine XR 0.1-0.4 mg/day than with placebo. Symptomatic improvement of ADHD was achieved following 2 weeks' treatment with clonidine XR. In both trials, significantly greater reductions from baseline in ADHD-RS-IV total scores were apparent at week 2 onwards for recipients of clonidine XR than for recipients of placebo. Clonidine XR was generally well tolerated as monotherapy and as adjunctive therapy with stimulant regimens in clinical trials in children and adolescents.
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Kim YH, Nam TS, Ahn DS, Chung S. Modulation of N-type Ca2+ currents by moxonidine via imidazoline I1 receptor activation in rat superior cervical ganglion neurons. Biochem Biophys Res Commun 2011; 409:645-50. [DOI: 10.1016/j.bbrc.2011.05.058] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 05/10/2011] [Indexed: 11/17/2022]
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Cognitive enhancers for the treatment of ADHD. Pharmacol Biochem Behav 2011; 99:262-74. [PMID: 21596055 DOI: 10.1016/j.pbb.2011.05.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 04/26/2011] [Accepted: 05/03/2011] [Indexed: 12/11/2022]
Abstract
Attention-deficit hyperactivity disorder (ADHD) is associated with multiple cognition-related phenotypic features in both children and adults. This review aims to clarify the role of cognition in ADHD and how prevailing treatments, which are often highly effective at reducing the clinical symptoms of the disorder, fare in modulating ADHD-related cognitive processes. First, we consider how the broad construct of cognition can be conceptualized in the context of ADHD. Second, we review the available evidence for how a range of both pharmacological and non-pharmacological interventions have fared with respect to enhancing cognition in individuals affected by this pervasive disorder. Findings from the literature suggest that the effects across a broad range of pharmacological and non-pharmacological interventions on the characteristic symptoms of ADHD can be distinguished from their effects on cognitive impairments. As such the direct clinical relevance of cognition enhancing effects of different interventions is somewhat limited. Recommendations for future research are discussed, including the identification of cognition-related endophenotypes, the refinement of the ADHD clinical phenotype, and studying the difference between acute and chronic treatment regimens.
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Edwards LP, Brown-Bryan TA, McLean L, Ernsberger P. Pharmacological Properties of the Central Antihypertensive Agent, Moxonidine. Cardiovasc Ther 2011; 30:199-208. [DOI: 10.1111/j.1755-5922.2011.00268.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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New imidazoline/α2-adrenoceptors affecting compounds—4(5)-(2-aminoethyl)imidazoline (dihydrohistamine) derivatives. Synthesis and receptor affinity studies. Bioorg Med Chem 2011; 19:156-67. [DOI: 10.1016/j.bmc.2010.11.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 11/16/2010] [Accepted: 11/17/2010] [Indexed: 11/22/2022]
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Bruijnzeel AW, Bishnoi M, van Tuijl IA, Keijzers KFM, Yavarovich KR, Pasek TM, Ford J, Alexander JC, Yamada H. Effects of prazosin, clonidine, and propranolol on the elevations in brain reward thresholds and somatic signs associated with nicotine withdrawal in rats. Psychopharmacology (Berl) 2010; 212:485-99. [PMID: 20697697 PMCID: PMC3042243 DOI: 10.1007/s00213-010-1970-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 07/20/2010] [Indexed: 11/26/2022]
Abstract
RATIONALE Tobacco withdrawal is characterized by a negative mood state and relatively mild somatic symptoms. Increased noradrenergic transmission has been reported to play an important role in opioid withdrawal, but little is known about the role of noradrenergic transmission in nicotine withdrawal. OBJECTIVES The aim of these experiments was to investigate the effects of prazosin, clonidine, and propranolol on the negative mood state and somatic signs associated with nicotine withdrawal in rats. METHODS A discrete-trial intracranial self-stimulation procedure was used to assess the negative affective state of nicotine withdrawal. Elevations in brain reward thresholds are indicative of a deficit in brain reward function. RESULTS In all the experiments, the nicotinic acetylcholine receptor antagonist mecamylamine (3 mg/kg) elevated the brain reward thresholds of the nicotine-treated rats and did not affect those of the control rats. The α1-adrenergic receptor antagonist prazosin (0.0625 and 0.125 mg/kg) dose-dependently attenuated the elevations in brain reward thresholds associated with precipitated nicotine withdrawal. The α2-adrenergic receptor agonist clonidine (10-40 μg/kg) and the nonselective β-adrenergic receptor antagonist propranolol (2.5-10 mg/kg) did not attenuate the elevations in brain reward thresholds associated with nicotine withdrawal. Furthermore, mecamylamine (2 mg/kg) induced more somatic signs in the nicotine-treated rats than in the control rats. Clonidine and propranolol, but not prazosin, decreased the total number of somatic signs associated with nicotine withdrawal. CONCLUSION Blockade of α1-adrenergic receptors attenuates the deficit in brain reward function associated with nicotine withdrawal. Antagonism of β-adrenergic receptors or stimulation of α2-adrenergic receptors attenuates the somatic symptoms of nicotine withdrawal.
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Affiliation(s)
- Adrie W Bruijnzeel
- Department of Psychiatry, McKnight Brain Institute, University of Florida, 100 S. Newell Dr., P.O. Box 100256, Gainesville, FL 32610, USA.
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Abstract
Pharmacologic management of attention-deficit/hyperactivity disorder (ADHD) has expanded beyond stimulant medications to include alpha-2 adrenergic agonists. These agents exert their actions through presynaptic stimulation and likely involve facilitation of dopamine and noradrenaline neurotransmission, both of which are thought to play critical roles in the pathophysiology of ADHD. Furthermore, frontostriatal dysfunction giving rise to neuropsychological weaknesses has been well-established in patients with ADHD and may explain how alpha-2 agents exert their beneficial effects. In the following review, we consider relevant neurobiological underpinnings of ADHD with respect to why alpha-2 agents may be effective in treating this condition. We also review new formulations of alpha-2 agonists, emerging data on their use in ADHD, and implications for clinical practice. Integrating knowledge of pathophysiologic mechanisms and mechanisms of drug action may inform our medication choices and facilitate treatment of ADHD and related disorders.
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Chung S, Ahn DS, Kim YH, Kim YS, Joeng JH, Nam TS. Modulation of N-type calcium currents by presynaptic imidazoline receptor activation in rat superior cervical ganglion neurons. Exp Physiol 2010; 95:982-93. [PMID: 20696781 DOI: 10.1113/expphysiol.2010.053355] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Presynaptic imidazoline receptors (R(i-pre)) are found in the sympathetic axon terminals of animal and human cardiovascular systems, and they regulate blood pressure by modulating the release of peripheral noradrenaline (NA). The cellular mechanism of R(i-pre)-induced inhibition of NA release is unknown. We, therefore, investigated the effect of R(i-pre) activation on voltage-dependent Ca(2+) channels in rat superior cervical ganglion (SCG) neurons, using the conventional whole-cell patch-clamp method. Cirazoline (30 μM), an R(i-pre) agonist as well as an α-adrenoceptor (R(α)) agonist, decreased Ca(2+) currents (I(Ca)) by about 50% in a voltage-dependent manner with prepulse facilitation. In the presence of low-dose rauwolscine (3 μM), which blocks the α(2)-adrenoceptor (R(α2)), cirazoline still inhibited I(Ca) by about 30%, but prepulse facilitation was significantly attenuated. This inhibitory action of cirazoline was almost completely prevented by high-dose rauwolscine (30 μM), which blocks R(i-pre) as well as R(α2). In addition, pretreatment with LY320135 (10 μM), another R(i-pre) antagonist, in combination with low-dose rauwolscine (3 μM), also blocked the R(α2)-resistant effect of cirazoline. Addition of guanosine-5-O-(2-thiodiphosphate) (2 mm) to the internal solutions significantly attenuated the action of cirazoline. However, pertussis toxin (500 ng ml(1)) did not significantly influence the inhibitory effect of cirazoline. Moreover, cirazoline (30 μM) suppressed M current in SCG neurons cultured overnight. Finally, omega-conotoxin (omega-CgTx) GVIA (1 μM) obstructed cirazoline-induced current inhibition, and cirazoline (30 μM) significantly decreased the frequency of action potential firing in a partly reversible manner. This cirazoline-induced inhibition of action potential firing was almost completely occluded in the presence of omega-CgTx. Taken together, our results suggest that activation of R(i-pre) in SCG neurons reduced N-type I(Ca) in a pertussis toxin- and voltage-insensitive pathway, and this inhibition attenuated repetitive action potential firing in SCG neurons.
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Affiliation(s)
- Seungsoo Chung
- Brain Korea 21 Project for Medical Science, Seoul, Republic of Korea
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Oppedal D, Goldsmith MI. A chemical screen to identify novel inhibitors of fin regeneration in zebrafish. Zebrafish 2010; 7:53-60. [PMID: 20384483 DOI: 10.1089/zeb.2009.0633] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We performed a chemical screen to look for novel inhibitors of zebrafish caudal fin regeneration. In a pilot screen, 520 compounds were tested. Two compounds, budesonide and AGN192403, abrogated fin regeneration. One compound in particular, AGN192403, targets the imidazoline receptor, a pathway not previously linked to fin regeneration. In addition to inhibiting regeneration of the adult fin, AGN192403 also blocked regeneration of the larval fin fold. Finally, the inhibitory effect of AGN192403 on fin regeneration persisted after removal of the drug. These studies demonstrate that chemical screening is feasible in adult zebrafish and that it is a reasonable strategy to use for exploring the biology of regeneration.
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Affiliation(s)
- Douglas Oppedal
- Department of Pediatrics, Washington University, St. Louis, Missouri 63110, USA
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35
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Rose C, Menzies FM, Renna M, Acevedo-Arozena A, Corrochano S, Sadiq O, Brown SD, Rubinsztein DC. Rilmenidine attenuates toxicity of polyglutamine expansions in a mouse model of Huntington's disease. Hum Mol Genet 2010; 19:2144-53. [PMID: 20190273 PMCID: PMC2865373 DOI: 10.1093/hmg/ddq093] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 02/03/2010] [Accepted: 02/25/2010] [Indexed: 11/30/2022] Open
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by a polyglutamine expansion in huntingtin. There are no treatments that are known to slow the neurodegeneration caused by this mutation. Mutant huntingtin causes disease via a toxic gain-of-function mechanism and has the propensity to aggregate and form intraneuronal inclusions. One therapeutic approach for HD is to enhance the degradation of the mutant protein. We have shown that this can be achieved by upregulating autophagy, using the drug rapamycin. In order to find safer ways of inducing autophagy for clinical purposes, we previously screened United States Food and Drug Administration-approved drugs for their autophagy-stimulating potential. This screen suggested that rilmenidine, a well tolerated, safe, centrally acting anti-hypertensive drug, could induce autophagy in cell culture via a pathway that was independent of the mammalian target of rapamycin. Here we have shown that rilmenidine induces autophagy in mice and in primary neuronal culture. Rilmenidine administration attenuated the signs of disease in a HD mouse model and reduced levels of the mutant huntingtin fragment. As rilmenidine has a long safety record and is designed for chronic use, our data suggests that it should be considered for the treatment of HD and related conditions.
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Affiliation(s)
- Claudia Rose
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK and
| | - Fiona M. Menzies
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK and
| | - Maurizio Renna
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK and
| | | | - Silvia Corrochano
- Medical Research Council Mammalian Genetics Unit, Harwell, Oxfordshire, UK
| | - Oana Sadiq
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK and
| | - Steve D. Brown
- Medical Research Council Mammalian Genetics Unit, Harwell, Oxfordshire, UK
| | - David C. Rubinsztein
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK and
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Cravo SL, Campos RR, Colombari E, Sato MA, Bergamaschi CM, Pedrino GR, Ferreira-Neto ML, Lopes OU. Role of the medulla oblongata in normal and high arterial blood pressure regulation: the contribution of Escola Paulista de Medicina - UNIFESP. AN ACAD BRAS CIENC 2010; 81:589-603. [PMID: 19722026 DOI: 10.1590/s0001-37652009000300021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Accepted: 05/13/2009] [Indexed: 11/22/2022] Open
Abstract
Several forms of experimental evidence gathered in the last 37 years have unequivocally established that the medulla oblongata harbors the main neural circuits responsible for generating the vasomotor tone and regulating arterial blood pressure. Our current understanding of this circuitry derives mainly from the studies of Pedro Guertzenstein, a former student who became Professor of Physiology at UNIFESP later, and his colleagues. In this review, we have summarized the main findings as well as our collaboration to a further understanding of the ventrolateral medulla and the control of arterial blood pressure under normal and pathological conditions.
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Affiliation(s)
- Sergio L Cravo
- Departamento de Fisiologia, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
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Triposkiadis F, Karayannis G, Giamouzis G, Skoularigis J, Louridas G, Butler J. The sympathetic nervous system in heart failure physiology, pathophysiology, and clinical implications. J Am Coll Cardiol 2009; 54:1747-62. [PMID: 19874988 DOI: 10.1016/j.jacc.2009.05.015] [Citation(s) in RCA: 628] [Impact Index Per Article: 41.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 05/11/2009] [Accepted: 05/14/2009] [Indexed: 01/12/2023]
Abstract
Heart failure is a syndrome characterized initially by left ventricular dysfunction that triggers countermeasures aimed to restore cardiac output. These responses are compensatory at first but eventually become part of the disease process itself leading to further worsening cardiac function. Among these responses is the activation of the sympathetic nervous system (SNS) that provides inotropic support to the failing heart increasing stroke volume, and peripheral vasoconstriction to maintain mean arterial perfusion pressure, but eventually accelerates disease progression affecting survival. Activation of SNS has been attributed to withdrawal of normal restraining influences and enhancement of excitatory inputs including changes in: 1) peripheral baroreceptor and chemoreceptor reflexes; 2) chemical mediators that control sympathetic outflow; and 3) central integratory sites. The interface between the sympathetic fibers and the cardiovascular system is formed by the adrenergic receptors (ARs). Dysregulation of cardiac beta(1)-AR signaling and transduction are key features of heart failure progression. In contrast, cardiac beta(2)-ARs and alpha(1)-ARs may function in a compensatory fashion to maintain cardiac inotropy. Adrenergic receptor polymorphisms may have an impact on the adaptive mechanisms, susceptibilities, and pharmacological responses of SNS. The beta-AR blockers and the inhibitors of the renin-angiotensin-aldosterone axis form the mainstay of current medical management of chronic heart failure. Conversely, central sympatholytics have proved harmful, whereas sympathomimetic inotropes are still used in selected patients with hemodynamic instability. This review summarizes the changes in SNS in heart failure and examines how modulation of SNS activity may affect morbidity and mortality from this syndrome.
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Arnsten AFT. Toward a new understanding of attention-deficit hyperactivity disorder pathophysiology: an important role for prefrontal cortex dysfunction. CNS Drugs 2009; 23 Suppl 1:33-41. [PMID: 19621976 DOI: 10.2165/00023210-200923000-00005] [Citation(s) in RCA: 255] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Recent advances in neurobiology have aided our understanding of attention-deficit hyperactivity disorder (ADHD). The higher-order association cortices in the temporal and parietal lobes and prefrontal cortex (PFC) interconnect to mediate aspects of attention. The parietal association cortices are important for orienting attentional resources in time/space, while the temporal association cortices analyse visual features critical for identifying objects/places. These posterior cortices are engaged by the salience of a stimulus (its physical characteristics such as movement and colour). Conversely, the PFC is critical for regulating attention based on relevance (i.e. its meaning). The PFC is important for screening distractions, sustaining attention and shifting/dividing attention in a task-appropriate manner. The PFC is critical for regulating behaviour/emotion, especially for inhibiting inappropriate emotions, impulses and habits. The PFC is needed for allocating/planning to achieve goals and organizing behaviour/thought. These regulatory abilities are often referred to as executive functions. In humans, the right hemisphere of the PFC is important for regulating distractions, inappropriate behaviour and emotional responses. Imaging studies of patients with ADHD indicate that these regions are underactive with weakened connections to other parts of the brain. The PFC regulates attention and behaviour through networks of interconnected pyramidal cells. These networks excite each other to store goals/rules to guide actions and are highly dependent on their neurochemical environment, as small changes in the catecholamines noradrenaline (NA) or dopamine (DA) can have marked effects on PFC function. NA and DA are released in the PFC according to our arousal state; too little (during fatigue or boredom) or too much (during stress) impairs PFC function. Optimal amounts are released when we are alert/interested. The beneficial effects of NA occur at postsynaptic alpha(2A)-receptors on the dendritic spines of PFC pyramidal cells. Stimulation of these receptors initiates a series of chemical events inside the cell. These chemical signals lead to the closing of special ion channels, thus strengthening the connectivity of network inputs to the cell. Conversely, the beneficial effects of moderate amounts of DA occur at D(1) receptors, which act by weakening irrelevant inputs to the cells on another set of spines. Genetic linkage studies of ADHD suggest that these catecholamine pathways may be altered in some families with ADHD, e.g. alterations in the enzyme that synthesizes NA (DA beta-hydroxylase) are associated with weakened PFC abilities. Pharmacological studies in animals indicate catecholamine actions in the PFC are highly relevant to ADHD. Blocking NA alpha(2A)-receptors in the PFC with yohimbine produces a profile similar to ADHD: locomotor hyperactivity, impulsivity and poor working memory. Conversely, drugs that enhance alpha(2)-receptor stimulation improve PFC function. Guanfacine directly stimulates postsynaptic alpha(2A)-receptors in the PFC and improves functioning, while methylphenidate and atomoxetine increase endogenous NA and DA levels and indirectly improve PFC function via alpha(2A)- and D(1) receptor actions. Methylphenidate and atomoxetine have more potent actions in the PFC than in subcortical structures, which may explain why proper administration of stimulant medications does not lead to abuse. Further understanding of the neurobiology of attention and impulse control will allow us to better tailor treatments for specific patient needs.
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Affiliation(s)
- Amy F T Arnsten
- Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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Gregoretti C, Decaroli D, Piacevoli Q, Mistretta A, Barzaghi N, Luxardo N, Tosetti I, Tedeschi L, Burbi L, Navalesi P, Azzeri F. Analgo-sedation of patients with burns outside the operating room. Drugs 2009; 68:2427-43. [PMID: 19016572 DOI: 10.2165/0003495-200868170-00003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Following the initial resuscitation of burn patients, the pain experienced may be divided into a 'background' pain and a 'breakthrough' pain associated with painful procedures. While background pain may be treated with intravenous opioids via continuous infusion or patient-controlled analgesia (PCA) and/or less potent oral opioids, breakthrough pain may be treated with a variety of interventions. The aim is to reduce patient anxiety, improve analgesia and ensure immobilization when required. Untreated pain and improper sedation may result in psychological distress such as post-traumatic stress disorder, major depression or delirium. This review summarizes recent developments and current techniques in sedation and analgesia in non-intubated adult burn patients during painful procedures performed outside the operating room (e.g. staple removal, wound-dressing, bathing). Current techniques of sedation and analgesia include different approaches, from a slight increase in background pain therapy (e.g. morphine PCA) to PCA with rapid-onset opioids, to multimodal drug combinations, nitrous oxide, regional blocks, or non-pharmacological approaches such as hypnosis and virtual reality. The most reliable way to administer drugs is intravenously. Fast-acting opioids can be combined with ketamine, propofol or benzodiazepines. Adjuvant drugs such as clonidine or NSAIDs and paracetamol (acetaminophen) have also been used. Patients receiving ketamine will usually maintain spontaneous breathing. This is an important feature in patients who are continuously turned during wound dressing procedures and where analgo-sedation is often performed by practitioners who are not specialists in anaesthesiology. Drugs are given in small boluses or by patient-controlled sedation, which is titrated to effect, according to sedation and pain scales. Patient-controlled infusion with propofol has also been used. However, we must bear in mind that burn patients often show an altered pharmacokinetic and pharmacodynamic response to drugs as a result of altered haemodynamics, protein binding and/or increased extracellular fluid volume, and possible changes in glomerular filtration. Because sedation and analgesia can range from minimal sedation (anxiolysis) to general anaesthesia, sedative and analgesic agents should always be administered by designated trained practitioners and not by the person performing the procedure. At least one individual who is capable of establishing a patent airway and positive pressure ventilation, as well as someone who can call for additional assistance, should always be present whenever analgo-sedation is administered. Oxygen should be routinely delivered during sedation. Blood pressure and continuous ECG monitoring should be carried out whenever possible, even if a patient is undergoing bathing or other procedures that may limit monitoring of vital pulse-oximetry parameters.
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Affiliation(s)
- Cesare Gregoretti
- Intensive Care Unit, Azienda Ospedaliera CTO-CRF-ICORMA, Turin, Italy
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Bellantuono V, Cassano G, Lippe C. The adrenergic receptor subtypes present in frog (Rana esculenta) skin. Comp Biochem Physiol C Toxicol Pharmacol 2008; 148:160-4. [PMID: 18544474 DOI: 10.1016/j.cbpc.2008.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 05/02/2008] [Accepted: 05/02/2008] [Indexed: 11/17/2022]
Abstract
Frog skin transports ions and water under hormonal control. In spite of the fundamental role played by adrenergic stimulation in maintaining the water balance of the organism, the receptor subtype(s) present in the skin have not been identified yet. We measured the increase in short-circuit current (ISC, an estimate of ion transport) induced by cirazoline, clonidine, xamoterol, formoterol, or BRL 37344, in order to verify the presence of alpha1, alpha2, beta1, beta2, or beta3 receptor subtypes, respectively. Only after treatment with formoterol, BRL 37344 and, to a lesser extent, cirazoline was measured a significant increase in ISC (57%, 33.2%, and 4.7%, respectively). The formoterol and BRL 37344 concentrations producing half-maximal effect (EC50) were 1.12 and 70.1 nM, respectively. Moreover, the formoterol effect was inhibited by treatment with ICI 118551 (antagonist of beta2 receptors) while SR 59230A (antagonist of beta3 receptors) had no effect; opposite findings were obtained when the BRL 37344 stimulation was investigated. Finally, by measuring the transepithelial fluxes of 22Na+ and 36Cl-, we demonstrated that Na+ absorption is increased by activation of beta2 and beta3 and is cAMP-sensitive, whereas the Cl- secretion is only increased by activation of beta2 receptors and is cAMP- and calmodulin-sensitive.
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Affiliation(s)
- Vito Bellantuono
- Department of General and Environmental Physiology, University of Bari, Via Amendola 165/A, 70126 Bari, Italy
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Hirono M, Matsunaga W, Chimura T, Obata K. Developmental enhancement of alpha2-adrenoceptor-mediated suppression of inhibitory synaptic transmission onto mouse cerebellar Purkinje cells. Neuroscience 2008; 156:143-54. [PMID: 18691636 DOI: 10.1016/j.neuroscience.2008.07.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 07/09/2008] [Accepted: 07/10/2008] [Indexed: 01/04/2023]
Abstract
Noradrenaline (NA) modulates glutamatergic and GABAergic transmission in various areas of the brain. It is reported that some alpha2-adrenoceptor subtypes are expressed in the cerebellar cortex and alpha2-adrenoceptors may play a role in motor coordination. Our previous study demonstrated that the selective alpha2-adrenoceptor agonist clonidine partially depresses spontaneous inhibitory postsynaptic currents (sIPSCs) in mouse cerebellar Purkinje cells (PCs). Here we found that the inhibitory effect of clonidine on sIPSCs was enhanced during postnatal development. The activation of alpha2-adrenoceptors by clonidine did not affect sIPSCs in PCs at postnatal days (P) 8-10, when PCs showed a few sIPSCs and interneurons in the molecular layer (MLIs) did not cause action potential (AP). In the second postnatal week, the frequency of sIPSCs increased temporarily and reached a plateau at P14. By contrast, MLIs began to fire at P11 with the firing rate gradually increasing thereafter and reaching a plateau at P21. In parallel with this rise in the rate of firing, the magnitude of the clonidine-mediated inhibition of sIPSCs increased during postnatal development. Furthermore, the magnitude of the clonidine-mediated firing suppression in MLIs, which seemed to be mediated by a reduction in amplitude of the hyperpolarization-activated nonselective cation current, I(h), was constant across development. Both alpha2A- and alpha2B-, but not alpha2C-, adrenoceptors were strongly expressed in MLIs at P13, and P31. Therefore, the developmental enhancement of the clonidine-mediated inhibition of sIPSCs is attributed to an age-dependent increase in AP-derived sIPSCs, which can be blocked by clonidine. Thus, presynaptic activation of alpha2-adrenoceptors inhibits cerebellar inhibitory synaptic transmission after the second postnatal week, leading to a restriction of NA signaling, which is mainly mediated by alpha1- and beta2-adrenoceptors in the adult cerebellar neuronal circuit.
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Affiliation(s)
- M Hirono
- Neuronal Circuit Mechanisms Research Group, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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Lapointe NP, Ung RV, Rouleau P, Guertin PA. Effects of Spinal α2-Adrenoceptor and I1-Imidazoline Receptor Activation on Hindlimb Movement Induction in Spinal Cord-Injured Mice. J Pharmacol Exp Ther 2008; 325:994-1006. [DOI: 10.1124/jpet.107.134874] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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Lee MJ, Shim HS, Seol GH, Kim PJ, Han SH, Yee J, Kim C, Lee KC, Kim HY, Min SS. Effects of Intra-articular Injection of Agmatine and Clonidine into the Knee Joint Cavity on the Induction and Maintenance of Arthritic Pain in Rats. Korean J Anesthesiol 2008. [DOI: 10.4097/kjae.2008.54.6.656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Myeong Jong Lee
- Department of Anesthesiology and Pain Medicine, Konkuk University College of Medicine, Chungju, Korea
| | - Hyen Soo Shim
- Department of Physiology andBiophysics, College of Medicine, Eulji University, Daejeon, Korea
| | - Geun Hee Seol
- Department of Basic Nursing Science, Korea University College of Nursing, Seoul, Korea
| | - Pill Joo Kim
- Professional Oriental Medicine Graduate School, Wonkwang University, Iksan, Korea
| | - Seung Ho Han
- Department of Physiology andBiophysics, College of Medicine, Eulji University, Daejeon, Korea
| | - Jaeyong Yee
- Department of Physiology andBiophysics, College of Medicine, Eulji University, Daejeon, Korea
| | - Chan Kim
- Department of Physiology andBiophysics, College of Medicine, Eulji University, Daejeon, Korea
| | - Kyu Chang Lee
- Department of Anesthesiology and Pain Medicine, Konkuk University College of Medicine, Chungju, Korea
| | - Hye Young Kim
- Department of Anesthesiology and Pain Medicine, Konkuk University College of Medicine, Chungju, Korea
| | - Sun Seek Min
- Department of Physiology andBiophysics, College of Medicine, Eulji University, Daejeon, Korea
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Arnsten AF, Scahill L, Findling RL. alpha2-Adrenergic receptor agonists for the treatment of attention-deficit/hyperactivity disorder: emerging concepts from new data. J Child Adolesc Psychopharmacol 2007; 17:393-406. [PMID: 17822336 DOI: 10.1089/cap.2006.0098] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Recent developments in the field of neuroscience have illuminated the understanding of the neural circuits impaired in attention-deficit/hyperactivity disorder (ADHD) and the mechanism of action of treatments used to treat this condition. There is an exciting confluence between emerging studies in basic neurobiology and the genetic, neuroimaging, and neuropsychological analyses of ADHD. The following provides a brief review of this field, explaining how compounds like guanfacine and the traditional stimulant medications can reduce the core symptoms of ADHD by optimizing the neurochemical environment in the prefrontal cortex (PFC). Knowledge of these basic mechanisms may inform our medication choices and facilitate treatment of ADHD and related disorders.
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Affiliation(s)
- Amy F Arnsten
- Director of Graduate Studies, Deparment of Neurobiology, Yale Medical School, New Haven, Connecticut 06520-8001, USA.
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Molderings GJ, Bönisch H, Brüss M, Wolf C, von Kügelgen I, Göthert M. S1P-receptors in PC12 and transfected HEK293 cells: molecular targets of hypotensive imidazoline I(1) receptor ligands. Neurochem Int 2007; 51:476-85. [PMID: 17559976 DOI: 10.1016/j.neuint.2007.04.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 04/23/2007] [Accepted: 04/27/2007] [Indexed: 02/07/2023]
Abstract
The present study aimed at elucidating the molecular identity of the proposed "I(1)-imidazoline receptors", i.e. non-adrenoceptor recognition sites via which the centrally acting imidazolines clonidine and moxonidine mediate a major part of their effects. In radioligand binding experiments with [(3)H]clonidine and [(3)H]lysophosphatidic acid on intact, alpha(2)-adrenoceptor-deficient PC12 cells, moxonidine, clonidine, lysophosphatidic acid and sphingosine-1-phosphate (S1P) competed for the specific binding sites of both radioligands with similar affinities. RNA interference with the rat S1P(1)-, S1P(2)- or S1P(3)-receptor abolished specific [(3)H]lysophosphatidic acid binding. [(3)H]Clonidine binding was markedly decreased by siRNA targeting S1P(1)- and S1P(3)-receptors but not by siRNA against S1P(2)-receptors. Finally, in HEK293 cells transiently expressing human S1P(3)-receptors, sphingosine-1-phosphate, clonidine and moxonidine induced increases in intracellular calcium concentration, moxonidine being more potent than clonidine; this is in agreement with the known properties of the "I(1)-imidazoline receptors". The present results indicate that the "I(1)-imidazoline receptors" mediating effects of clonidine and moxonidine in PC12 and the transfected HEK293 cells belong to the S1P-receptor family; in particular, the data obtained in PC12 cells suggest that the I(1) imidazoline receptors represent a mixture of S1P(1)- and S1P(3)-receptors and/or hetero-dimers of both.
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Affiliation(s)
- Gerhard J Molderings
- University of Bonn, Institute of Pharmacology and Toxicology, Reuterstr. 2b, D-53113 Bonn, Germany.
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Sun Z, Chang CH, Ernsberger P. Identification of IRAS/Nischarin as an I1-imidazoline receptor in PC12 rat pheochromocytoma cells. J Neurochem 2007; 101:99-108. [PMID: 17254010 DOI: 10.1111/j.1471-4159.2006.04413.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The I1-imidazoline receptor (I1R) is a proposed target for drug action relevant to blood pressure and glucose control. The imidazoline receptor antisera-selected (IRAS) gene, also known as Nischarin, has several characteristics of an I1R. To test the contribution of IRAS to I1R binding capacity and cell-signaling function, an antisense probe targeting the initiating codon of rat IRAS gene was evaluated in PC12 rat pheochromocytoma cells, a well-established model for I1R action. The density of I1R was significantly reduced by antisense compared with control transfection (Bmax = 400 +/- 16 vs. 691 +/- 29 fmol/mg protein), without significantly affecting binding affinity (Kd = 0.30 +/- 0.04 vs. 0.39 +/- 0.05 nmol/L). Thus, IRAS expression is necessary for high-affinity binding to I1R. Western blots with polyclonal anti-IRAS showed reduced IRAS expression in the major 85-kDa band relative to an actin reference, paralleling the reduction in binding site density. To determine whether reduced IRAS expression attenuated I1R cell signaling, PC12 cells transfected with antisense or sense oligo-DNA were treated with moxonidine, an I1R agonist, then cell lysates were analyzed by western blot. Dose-dependent activation of extracellular signal-regulated kinase was attenuated without affecting the potency of the agonist. In contrast, extracellular signal-regulated kinase activation by insulin was unchanged. The IRAS gene is likely to encode an I1R or a functional subunit.
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Affiliation(s)
- Zheng Sun
- Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4906, USA
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Tahsili-Fahadan P, Yahyavi-Firouz-Abadi N, Khoshnoodi MA, Motiei-Langroudi R, Tahaei SA, Ghahremani MH, Dehpour AR. Agmatine potentiates morphine-induced conditioned place preference in mice: modulation by alpha2-adrenoceptors. Neuropsychopharmacology 2006; 31:1722-32. [PMID: 16237388 DOI: 10.1038/sj.npp.1300929] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The effects of agmatine, an endogenous polyamine metabolite formed by decarboxylation of L-arginine, and its combination with morphine on conditioned place preference (CPP) has been investigated in male mice. Our data show that subcutaneous administration of morphine (1-7.5 mg/kg) significantly increases the time spent in the drug-paired compartment in a dose-dependent manner. Intraperitoneal administration of agmatine (1-40 mg/kg) alone does not induce either CPP or conditioned place aversion, while combination of agmatine and subeffective doses of morphine leads to potent rewarding effects. Lower doses of morphine (0.1, 0.05, and 0.01 mg/kg) are able to induce CPP in mice pretreated with agmatine 1, 5, and 10 mg/kg, respectively. Concomitant intraperitoneal administration of UK 14 304 (0.5 mg/kg), a highly selective alpha2-agonist, with per se noneffective dose of morphine (0.5 mg/kg) and also its combination with noneffective doses of agmatine (1 mg/kg) plus morphine (0.05 mg/kg) produces significant CPP. UK 14 304 (0.05, 0.5 mg/kg) alone, or in combination with agmatine (1, 5 mg/kg) have had no effect. We have further investigated the possible involvement of the alpha2-adrenoceptors in the potentiating effect of agmatine on morphine-induced place preference. Selective alpha2-antagonists, yohimbine (0.005 mg/kg) and RX821002 (0.1, 0.5 mg/kg), block the CPP induced by concomitant administration of agmatine (5 mg/kg) and morphine (0.05 mg/kg). Yohimbine (0.001-0.05 mg/kg) or RX821002 (0.05-0.5 mg/kg) alone or in combination with morphine (0.05 mg/kg) or agmatine (5 mg/kg) fail to show any significant place preference or aversion. Our results indicate that pretreatment of animals with agmatine enhances the rewarding properties of morphine via a mechanism which may involve alpha2-adrenergic receptors.
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Affiliation(s)
- Pouya Tahsili-Fahadan
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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Jiménez-Mena LR, Gupta S, Muñoz-Islas E, Lozano-Cuenca J, Sánchez-López A, Centurión D, Mehrotra S, MaassenVanDenBrink A, Villalón CM. Clonidine inhibits the canine external carotid vasodilatation to capsaicin by α2A/2C-adrenoceptors. Eur J Pharmacol 2006; 543:68-76. [PMID: 16814767 DOI: 10.1016/j.ejphar.2006.05.041] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Revised: 05/13/2006] [Accepted: 05/16/2006] [Indexed: 11/28/2022]
Abstract
Migraine is a disorder associated with increased plasma concentrations of calcitonin gene-related peptide (CGRP). CGRP, a neuropeptide released from activated trigeminal sensory nerves, dilates cranial blood vessels and transmits vascular nociception. Moreover, several antimigraine drugs inhibit the dural neurogenic vasodilatation to trigeminal stimulation. Hence, this study investigated in anaesthetized dogs the effects of the alpha(2)-adrenoceptor agonist, clonidine, on the external carotid vasodilator responses to capsaicin, alpha-CGRP and acetylcholine. 1-min intracarotid infusions of capsaicin (10, 18, 30 and 56 microg/min), alpha-CGRP (0.1, 0.3, 1 and 3 microg/min) and acetylcholine (0.01, 0.03, 0.1 and 0.3 microg/min) produced dose-dependent increases in external carotid conductance without affecting blood pressure or heart rate. Interestingly, the carotid vasodilator responses to capsaicin, but not those to alpha-CGRP or acetylcholine, were partially inhibited after clonidine (total dose: 24.4 microg/kg, i.v.); in contrast, equivalent volumes of saline did not affect the responses to capsaicin, alpha-CGRP or acetylcholine. The inhibitory responses to clonidine were antagonized by i.v. administration of the alpha(2)-adrenoceptor antagonists rauwolscine (alpha(2A/2B/2C); 300 microg/kg), BRL44408 (alpha(2A); 1000 microg/kg) or MK912 (alpha(2C); 100 and 300 microg/kg), but not by imiloxan (alpha(2B); 1000 microg/kg). These results suggest that clonidine inhibits the external carotid vasodilator responses to capsaicin by peripheral trigeminovascular and/or central mechanisms; this inhibitory response to clonidine seems to be predominantly mediated by alpha(2A)-adrenoceptors and, to a much lesser extent, by alpha(2C)-adrenoceptors.
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Affiliation(s)
- Luisa R Jiménez-Mena
- Departamento de Farmacobiología, Cinvestav-Coapa, Czda. de los Tenorios 235, Col. Granjas-Coapa, Deleg. Tlalpan, C.P. 14330, México DF, México
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Díez-Alarcia R, Pilar-Cuéllar F, Paniagua MA, Meana JJ, Fernández-López A. Pharmacological characterization and autoradiographic distribution of α2-adrenoceptor antagonist [3H]RX 821002 binding sites in the chicken brain. Neuroscience 2006; 141:357-69. [PMID: 16697114 DOI: 10.1016/j.neuroscience.2006.03.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Revised: 03/10/2006] [Accepted: 03/16/2006] [Indexed: 11/23/2022]
Abstract
Knowledge about the noradrenergic system in birds is very scarce even though their biological diversity and complex social behavior make them an excellent model for studying neuronal functions and developmental biology. While the role of norepinephrine has been described in depth in a large number of central and peripheral functions in mammals, reports for avian species are limited. The radioligand [(3)H]RX 821002 ([(3)H]1,4-[6,7(n)3H]-benzodioxan-2-methoxy-2-yl)-2-imidazol) has been used to map and characterize alpha(2)-adrenoceptors through the chicken brain using in vitro autoradiography and membrane homogenates binding assays. [(3)H]RX 821002 showed a saturable and high affinity binding to a site compatible with alpha(2)-adrenoceptor, and to a serotonergic component. The autoradiographic assays displayed a similar alpha(2)-adrenoceptor distribution than those previously reported in birds using other radioligands such as [(3)H]UK 14304 ([(3)H]5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine) or [(3)H]clonidine. [(3)H]RX 821002 binding pharmacological characterization was carried out in different chicken brain regions using membrane homogenates for competition assays with different alpha(2)-adrenoceptor agonists and antagonists drugs (oxymetazoline, BRL 44408 [2-(2H-(1-methyl-1,3-dihydroisoindole)methyl)-4,5-dihydroimidazole] ARC 239 [2-(2-4-(O-methoxyphenyl)-piperazin-1-yl)-ethyl-4,4-dimethyl-1,3-(2H,4H)-isoquinolindione], prazosin, UK 14304 and RX 821002). The results showed alpha(2A) as the predominant alpha(2)-adrenoceptor subtype in the chicken brain while alpha(2B)- and/or alpha(2C)-adrenoceptor subtypes were detected only in the telencephalon. RX 821002, serotonin (5-HT) and 8-OH-DPAT [8-hydroxy-2-(di-n-propylamino)tetralin] competition assays, and competition binding assays performed in the presence of serotonin demonstrated that [(3)H]RX 821002 binds with higher affinity to a serotonergic component, probably 5-HT(1A) receptors, than to the alpha(2)-adrenoceptors. Similar pharmacological properties for the alpha(2)-adrenoceptor component were observed both in rat and chicken brain. The results demonstrate that the different alpha(2)-adrenoceptor subtypes are present in chicken brain and suggest that these receptors are highly conserved through evolution.
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Affiliation(s)
- R Díez-Alarcia
- Department of Cell Biology and Anatomy, Faculty of Biological and Environmental Sciences, University of Leon, Leon 24071, Spain
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