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Zhou P, Lu F, Zhu H, Shi B, Wang X, Sun S, Li Y, Su R. The Discovery of Novel α 2a Adrenergic Receptor Agonists Only Coupling to Gαi/O Proteins by Virtual Screening. Int J Mol Sci 2024; 25:7233. [PMID: 39000340 PMCID: PMC11241340 DOI: 10.3390/ijms25137233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 06/23/2024] [Accepted: 06/26/2024] [Indexed: 07/16/2024] Open
Abstract
Most α2-AR agonists derived from dexmedetomidine have few structural differences between them and have no selectivity for α2A/2B-AR or Gi/Gs, which can lead to side effects in drugs. To obtain novel and potent α2A-AR agonists, we performed virtual screening for human α2A-AR and α2B-AR to find α2A-AR agonists with higher selectivity. Compound P300-2342 and its three analogs significantly decreased the locomotor activity of mice (p < 0.05). Furthermore, P300-2342 and its three analogs inhibited the binding of [3H] Rauwolscine with IC50 values of 7.72 ± 0.76 and 12.23 ± 0.11 μM, respectively, to α2A-AR and α2B-AR. In α2A-AR-HEK293 cells, P300-2342 decreased forskolin-stimulated cAMP production without increasing cAMP production, which indicated that P300-2342 activated α2A-AR with coupling to the Gαi/o pathway but without Gαs coupling. P300-2342 exhibited no agonist but slight antagonist activities in α2B-AR. Similar results were obtained for the analogs of P300-2342. The docking results showed that P300-2342 formed π-hydrogen bonds with Y394, V114 in α2A-AR, and V93 in α2B-AR. Three analogs of P300-2342 formed several π-hydrogen bonds with V114, Y196, F390 in α2A-AR, and V93 in α2B-AR. We believe that these molecules can serve as leads for the further optimization of α2A-AR agonists with potentially few side effects.
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Affiliation(s)
- Peilan Zhou
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing 100850, China; (F.L.); (H.Z.); (B.S.); (X.W.); (S.S.); (Y.L.)
| | | | | | | | | | | | | | - Ruibin Su
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Key Laboratory of Neuropsychopharmacology, Beijing Institute of Pharmacology and Toxicology, 27th Taiping Road, Beijing 100850, China; (F.L.); (H.Z.); (B.S.); (X.W.); (S.S.); (Y.L.)
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Raza A, Mohsin S, Saeed F, Ali SA, Chotani MA. Inhibiting Intracellular α 2C-Adrenoceptor Surface Translocation Using Decoy Peptides: Identification of an Essential Role of the C-Terminus in Receptor Trafficking. Int J Mol Sci 2023; 24:17558. [PMID: 38139390 PMCID: PMC10744278 DOI: 10.3390/ijms242417558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 12/07/2023] [Accepted: 12/10/2023] [Indexed: 12/24/2023] Open
Abstract
The G protein-coupled α2-adrenoceptor subtype C (abbreviated α2C-AR) has been implicated in peripheral vascular conditions and diseases such as cold feet-hands, Raynaud's phenomenon, and scleroderma, contributing to morbidity and mortality. Microvascular α2C-adrenoceptors are expressed in specialized smooth muscle cells and mediate constriction under physiological conditions and the occlusion of blood supply involving vasospastic episodes and tissue damage under pathological conditions. A crucial step for receptor biological activity is the cell surface trafficking of intracellular receptors, triggered by cAMP-Epac-Rap1A GTPase signaling, which involves protein-protein association with the actin-binding protein filamin-2, mediated by critical amino acid residues in the last 14 amino acids of the receptor carboxyl (C)-terminus. This study assessed the role of the C-terminus in Rap1A GTPase coupled receptor trafficking by domain-swapping studies using recombinant tagged receptors in transient co-transfections and compared with wild-type receptors using immunofluorescence microscopy. We further tested the biological relevance of the α2C-AR C-terminus, when introduced as competitor peptides, to selectively inhibit intracellular α2C-AR surface translocation in transfected as well as in microvascular smooth muscle cells expressing endogenous receptors. These studies contribute to establishing proof of principle to target intracellular α2C-adrenoceptors to reduce biological activity, which in clinical conditions can be a target for therapy.
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Affiliation(s)
- Aisha Raza
- Dr. Panjwani Center for Molecular Medicine and Drug Research (PCMD), International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan; (A.R.); (S.M.); (F.S.)
| | - Saima Mohsin
- Dr. Panjwani Center for Molecular Medicine and Drug Research (PCMD), International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan; (A.R.); (S.M.); (F.S.)
| | - Fasiha Saeed
- Dr. Panjwani Center for Molecular Medicine and Drug Research (PCMD), International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan; (A.R.); (S.M.); (F.S.)
| | - Syed Abid Ali
- Husein Ebrahim Jamal (H.E.J.) Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan;
| | - Maqsood A. Chotani
- Dr. Panjwani Center for Molecular Medicine and Drug Research (PCMD), International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan; (A.R.); (S.M.); (F.S.)
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Wang S, Haikarainen A, Pohjakallio A, Sipilä J, Kaskinoro J, Juhila S, Jalava N, Koskinen M, Vesajoki M, Kumpulainen E, Pystynen J, Koskelainen T, Holm P, Din Belle D. 2,3-Dihydrobenzo-dioxine piperidine derivatives as potent and selective α2c antagonists. Bioorg Med Chem Lett 2022; 69:128783. [PMID: 35569686 DOI: 10.1016/j.bmcl.2022.128783] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/21/2022] [Accepted: 05/09/2022] [Indexed: 11/02/2022]
Abstract
In this manuscript, we report a series of benzodioxine methyl piperidine derivatives as highly potent and selective α2C antagonists by ligand design to improve the pharmacokinetics of a previous candidate molecule.
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Affiliation(s)
- Shouming Wang
- Department of Medicinal Chemistry, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland.
| | - Anssi Haikarainen
- Department of Medicinal Chemistry, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland
| | - Antti Pohjakallio
- Department of Medicinal Chemistry, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland
| | - Julius Sipilä
- Department of Medicinal Chemistry, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland
| | - Janne Kaskinoro
- Department of DMPK & Safety Science, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland
| | - Satu Juhila
- Department of DMPK & Safety Science, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland
| | - Niina Jalava
- Department of CNS Research, Orion Corporation Orion Pharma, Tengströminkatu 8, 20360, Turku, Finland
| | - Mikko Koskinen
- Department of DMPK & Safety Science, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland
| | - Marja Vesajoki
- Department of Biology, Orion Corporation Orion Pharma, Tengströminkatu 8, 20360 Turku, Finland
| | - Esa Kumpulainen
- Department of Medicinal Chemistry, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland
| | - Jarmo Pystynen
- Department of Medicinal Chemistry, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland
| | - Tuula Koskelainen
- Department of Medicinal Chemistry, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland
| | - Patrik Holm
- Department of Medicinal Chemistry, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland
| | - David Din Belle
- Department of Medicinal Chemistry, Orion Corporation Orion Pharma, Orionintie 1, PL 65, FI-02101, Finland
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Characterization of Chicken α2A-Adrenoceptor: Molecular Cloning, Functional Analysis, and Its Involvement in Ovarian Follicular Development. Genes (Basel) 2022; 13:genes13071113. [PMID: 35885896 PMCID: PMC9315859 DOI: 10.3390/genes13071113] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 06/17/2022] [Accepted: 06/17/2022] [Indexed: 01/21/2023] Open
Abstract
Adrenoceptors are suggested to mediate the functions of norepinephrine (NE) and epinephrine (EPI) in the central nervous system (CNS) and peripheral tissues in vertebrates. Compared to mammals, the functionality and expression of adrenoceptors have not been well characterized in birds. Here, we reported the structure, expression, and functionality of chicken functional α2A-adrenoceptor, named ADRA2A. The cloned chicken ADRA2A cDNA is 1335 bp in length, encoding the receptor with 444 amino acids (a.a.), which shows high amino acid sequence identity (63.4%) with its corresponding ortholog in humans. Using cell-based luciferase reporter assays and Western blot, we demonstrated that the ADRA2A could be activated by both NE and EPI through multiple signaling pathways, including MAPK/ERK signaling cascade. In addition, the mRNA expression of ADRA2A is found to be expressed abundantly in adult chicken tissues including thyroid, lung, ovary and adipose from the reported RNA-Seq data sets. Moreover, the mRNA expression of ADRA2A is also found to be highly expressed in the granulosa cells of 6–8 mm and F5 chicken ovarian follicles, which thus supports that ADRA2A signaling may play a role in ovarian follicular growth and differentiation. Taken together, our data provide the first proof that the α2A-adrenoceptor is functional in birds involving avian ovarian follicular development.
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Xu J, Cao S, Hübner H, Weikert D, Chen G, Lu Q, Yuan D, Gmeiner P, Liu Z, Du Y. Structural insights into ligand recognition, activation, and signaling of the α 2A adrenergic receptor. SCIENCE ADVANCES 2022; 8:eabj5347. [PMID: 35245122 PMCID: PMC8896805 DOI: 10.1126/sciadv.abj5347] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The α2A adrenergic receptor (α2AAR) is a G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor that mediates important physiological functions in response to the endogenous neurotransmitters norepinephrine and epinephrine, as well as numerous chemically distinct drugs. However, the molecular mechanisms of drug actions remain poorly understood. Here, we report the cryo-electron microscopy structures of the human α2AAR-GoA complex bound to norepinephrine and three imidazoline derivatives (brimonidine, dexmedetomidine, and oxymetazoline). Together with mutagenesis and functional data, these structures provide important insights into the molecular basis of ligand recognition, activation, and signaling at the α2AAR. Further structural analyses uncover different molecular determinants between α2AAR and βARs for recognition of norepinephrine and key regions that determine the G protein coupling selectivity. Overall, our studies provide a framework for understanding the signal transduction of the adrenergic system at the atomic level, which will facilitate rational structure-based discovery of safer and more effective medications for α2AAR.
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Affiliation(s)
- Jun Xu
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Sheng Cao
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Harald Hübner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich-Alexander University, Nikolaus-Fiebiger-Straße 10, 91058 Erlangen, Germany
| | - Dorothée Weikert
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich-Alexander University, Nikolaus-Fiebiger-Straße 10, 91058 Erlangen, Germany
| | - Geng Chen
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Qiuyuan Lu
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
| | - Daopeng Yuan
- Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University, Beijing 100084, China
- Corresponding author. (D.Y.); (P.G.); (Z.L.); (Y.D.)
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Friedrich-Alexander University, Nikolaus-Fiebiger-Straße 10, 91058 Erlangen, Germany
- Corresponding author. (D.Y.); (P.G.); (Z.L.); (Y.D.)
| | - Zheng Liu
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
- Corresponding author. (D.Y.); (P.G.); (Z.L.); (Y.D.)
| | - Yang Du
- Kobilka Institute of Innovative Drug Discovery, School of Life and Health Sciences, Chinese University of Hong Kong, Shenzhen, 518172, China
- Corresponding author. (D.Y.); (P.G.); (Z.L.); (Y.D.)
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Palm D, Uzoni A, Simon F, Tucha O, Thome J, Faltraco F. Norepinephrine influences the circadian clock in human dermal fibroblasts from study participants with a diagnosis of attention-deficit hyperactivity disorder. J Neural Transm (Vienna) 2021; 128:1147-1157. [PMID: 34275002 PMCID: PMC8295072 DOI: 10.1007/s00702-021-02376-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 06/27/2021] [Indexed: 12/16/2022]
Abstract
Attention-deficit hyperactivity disorder (ADHD) is characterized by changes to the circadian process. Many medications used to treat the condition, influence norepinephrine levels. Several studies have, in addition, reported that norepinephrine itself has an effect on circadian function. The aim of this study was to investigate the circadian gene expression in primary human-derived dermal fibroblast cultures (HDF) after norepinephrine exposure. We analyzed circadian preference, behavioral circadian and sleep parameters as well as the circadian gene expression in a cohort of healthy controls and participants with an ADHD diagnosis. Circadian preference was evaluated with German Morningness–Eveningness Questionnaire (D-MEQ) and rhythms of sleep/wake behavior were assessed via actigraphy. After ex vivo exposure to different norepinephrine concentrations in HDF cultures, the rhythmicity of circadian gene expression was analyzed via qRT-PCR. The exposure of 1 µM norepinephrine to confluent cultures of human dermal fibroblasts from participants with a diagnosis of ADHD, was shown to dampen Per1 rhythmicity. The expression of Bmal1, Per1 and Per3 in control subjects was also influenced by incubation with 1 µM norepinephrine. Cultures from the ADHD group revealed no statistically significant overall differences in circadian gene expression, between cultures with and without norepinephrine incubation. Per3 expression showed a significant ZT × group interaction via mixed ANOVA. Per3 expression at ZT4 was significant higher in the group of control samples incubated with 1 µM norepinephrine, compared to the control group without norepinephrine. This effect was also shown in the control samples incubated with 1 µM norepinephrine and cultures from subjects with ADHD without norepinephrine incubation. Per3 expression differed between the healthy control group and the ADHD group without norepinephrine incubation at ZT28. The results of the present study illustrate that norepinephrine impacts on circadian function. In both groups, control group and cultures taken from subjects with ADHD, the expression of the periodic genes (Per1–3) was significantly influenced by incubation with norepinephrine.
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Affiliation(s)
- Denise Palm
- Department of Psychiatry and Psychotherapy, University Medical Centre Rostock, Rostock, Gehlsheimer Str. 20, 18147, Rostock, Germany
| | - Adriana Uzoni
- Department of Psychiatry and Psychotherapy, University Medical Centre Rostock, Rostock, Gehlsheimer Str. 20, 18147, Rostock, Germany
| | - Frederick Simon
- Department of Psychiatry and Psychotherapy, University Medical Centre Rostock, Rostock, Gehlsheimer Str. 20, 18147, Rostock, Germany
| | - Oliver Tucha
- Department of Psychiatry and Psychotherapy, University Medical Centre Rostock, Rostock, Gehlsheimer Str. 20, 18147, Rostock, Germany
| | - Johannes Thome
- Department of Psychiatry and Psychotherapy, University Medical Centre Rostock, Rostock, Gehlsheimer Str. 20, 18147, Rostock, Germany
| | - Frank Faltraco
- Department of Psychiatry and Psychotherapy, University Medical Centre Rostock, Rostock, Gehlsheimer Str. 20, 18147, Rostock, Germany.
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Eldeeb HM, Elgharabawy RM, Abd Elmoniem AE, Ahmed AA. Alpha-2 beta-adrenergic receptor (301-303 I/D) gene polymorphism in hypertension and type 2 diabetes mellitus diseases among Saudi cases in the Qassim region. Sci Prog 2021; 104:368504211012162. [PMID: 33900865 PMCID: PMC10454788 DOI: 10.1177/00368504211012162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The hypertension (HTN) and type 2 diabetes mellitus (T2DM) are a common multifactorial disease due to genetics and environmental factors. The alpha 2B adrenergic receptor (α2B-AR) has relationship with secretion of insulin and mediates the vasoconstriction that elevate blood pressure. This study aimed to determine the association between α2B-AR gene polymorphism with HTN and T2DM in Saudi cases. 200 cases and 100 healthy controls from Saudi population were recruited from the Internal Medicine clinic, Qassim University. The patients were grouped into: 72 HTN without T2DM; 62 HTN with T2DM and 66 T2DM only. Full medical history, examination and biochemical assays were performed for all participants. Genomic DNA was isolated from blood lymphocytes of all subjects for detection of α2B-AR gene polymorphism by using polymerase chain reaction (PCR). The results found a significant association between D carriers genotype and HTN with T2DM cases (p < 0.05) as well as with T2DM-only cases, (p < 0.05) compared to control. Regardless of HTN status, only cases with HTN and T2DM as well as those with T2DM were significantly associated with the recessive model DD versus II+ID (p < 0.05). So, D carriers genotype was significantly associated with total cases of HTN and T2DM (p < 0.05) compared to controls. Our results suggested that there is a relationship between the α2B-AR I/D gene polymorphism and the risk for T2DM with or without HTN, but no such comparable relationship is evident with HTN-only cases among Saudi population in Qassim region.
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Affiliation(s)
- Hussein Mohammad Eldeeb
- Department of Pharmacology and Toxicology, College of Pharmacy, Qassim University, Buraydah, Kingdom of Saudi Arabia
- Department of Biochemistry, Faculty of Medicine, Al-Azhar University, Assiut, Egypt
| | - Rehab M. Elgharabawy
- Department of Pharmacology and Toxicology, College of Pharmacy, Qassim University, Buraydah, Kingdom of Saudi Arabia
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tanta University, Tanta, Egypt
| | - Alaa E Abd Elmoniem
- Internal Medicine and Cardiology, College of Medicine, Qassim University, Kingdom of Saudi Arabia
- Internal Medicine and Cardiology, College of Medicine, Assiut University, Egypt
| | - Ahmed Ali Ahmed
- Research Center of Biotechnology, College of Medicine, Qassim University, Kingdom of Saudi Arabia
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Jang HS, Kim J, Padanilam BJ. Renal sympathetic nerve activation via α 2-adrenergic receptors in chronic kidney disease progression. Kidney Res Clin Pract 2019; 38:6-14. [PMID: 30831675 PMCID: PMC6481969 DOI: 10.23876/j.krcp.18.0143] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/11/2018] [Accepted: 12/15/2018] [Indexed: 12/12/2022] Open
Abstract
Chronic kidney disease (CKD) is increasing worldwide without an effective therapeutic strategy. Sympathetic nerve activation is implicated in CKD progression, as well as cardiovascular dysfunction. Renal denervation is beneficial for controlling blood pressure (BP) and improving renal function through reduction of sympathetic nerve activity in patients with resistant hypertension and CKD. Sympathetic neurotransmitter norepinephrine (NE) via adrenergic receptor (AR) signaling has been implicated in tissue homeostasis and various disease progressions, including CKD. Increased plasma NE level is a predictor of survival and the incidence of cardiovascular events in patients with end-stage renal disease, as well as future renal injury in subjects with normal BP and renal function. Our recent data demonstrate that NE derived from renal nerves causes renal inflammation and fibrosis progression through alpha-2 adrenergic receptors (α2-AR) in renal fibrosis models independent of BP. Sympathetic nerve activation-associated molecular mechanisms and signals seem to be critical for the development and progression of CKD, but the exact role of sympathetic nerve activation in CKD progression remains undefined. This review explores the current knowledge of NE-α2-AR signaling in renal diseases and offers prospective views on developing therapeutic strategies targeting NE-AR signaling in CKD progression.
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Affiliation(s)
- Hee-Seong Jang
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Jinu Kim
- Department of Anatomy, Jeju National University School of Medicine, Jeju, Korea.,Department of Biomedicine and Drug Development, Jeju National University, Jeju, Korea
| | - Babu J Padanilam
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA.,Department of Internal Medicine, Section of Nephrology, University of Nebraska Medical Center, Omaha, NE, USA
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Han X, Liu Y, Kam WR, Sullivan DA. Effect of brimonidine, an α2 adrenergic agonist, on human meibomian gland epithelial cells. Exp Eye Res 2018; 170:20-28. [PMID: 29452108 DOI: 10.1016/j.exer.2018.02.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/09/2018] [Accepted: 02/12/2018] [Indexed: 01/15/2023]
Abstract
We recently discovered that the anti-glaucoma pharmaceuticals timolol, a β adrenergic antagonist, and pilocarpine, a cholinergic compound, negatively influence the morphology, proliferative capacity and survival of human meibomian gland epithelial cells (HMGECs). We hypothesize that another class of anti-glaucoma drugs, the α2 adrenergic agonists, also acts directly on HMGECs to affect their structure and function. We tested this hypothesis. Immortalized (i) HMGECs were cultured with brimonidine, as well as clonidine (α2 agonist), phenylephrine (α1 agonist), RX821002 (inverse α2 agonist) and MK912 (neutral α2 agonist) for up to 7 days. Cells were counted with a hemocytometer, and evaluated for morphology, signaling pathway activity, protein biomarker expression, and the accumulation of neutral lipids, phospholipids and lysosomes. Our findings demonstrate that brimondine treatment induces a dose-dependent decrease in Akt signaling and proliferation of iHMGECs. In contrast, brimonidine also promotes a dose-dependent differentiation of iHMGECs, including an increase in neutral lipid, phospholipid and lysosome levels. These effects were paralleled by an inhibition of p38 signaling, and duplicated by cellular exposure to clonidine, but not phenylephrine. Brimonidine also enhanced the cellular content of sterol regulatory binding protein-1, a master regulator of lipid synthesis. Of particular interest, the putative α2 antagonists, RX821002 and MK912, did not interfere with brimonidine action, but rather stimulated IHMGEC differentiation. Our results support our hypothesis and demonstrate that α2 adrenergic agonists act directly on iHMGECs. However, these compounds do not elicit an overall negative effect. Rather, the α2 agonists promote the differentiation of iHMGECs.
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Affiliation(s)
- Xi Han
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yang Liu
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Wendy R Kam
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - David A Sullivan
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.
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Uys MM, Shahid M, Harvey BH. Therapeutic Potential of Selectively Targeting the α 2C-Adrenoceptor in Cognition, Depression, and Schizophrenia-New Developments and Future Perspective. Front Psychiatry 2017; 8:144. [PMID: 28855875 PMCID: PMC5558054 DOI: 10.3389/fpsyt.2017.00144] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 07/24/2017] [Indexed: 12/12/2022] Open
Abstract
α2A- and α2C-adrenoceptors (ARs) are the primary α2-AR subtypes involved in central nervous system (CNS) function. These receptors are implicated in the pathophysiology of psychiatric illness, particularly those associated with affective, psychotic, and cognitive symptoms. Indeed, non-selective α2-AR blockade is proposed to contribute toward antidepressant (e.g., mirtazapine) and atypical antipsychotic (e.g., clozapine) drug action. Both α2C- and α2A-AR share autoreceptor functions to exert negative feedback control on noradrenaline (NA) release, with α2C-AR heteroreceptors regulating non-noradrenergic transmission (e.g., serotonin, dopamine). While the α2A-AR is widely distributed throughout the CNS, α2C-AR expression is more restricted, suggesting the possibility of significant differences in how these two receptor subtypes modulate regional neurotransmission. However, the α2C-AR plays a more prominent role during states of low endogenous NA activity, while the α2A-AR is relatively more engaged during states of high noradrenergic tone. Although augmentation of conventional antidepressant and antipsychotic therapy with non-selective α2-AR antagonists may improve therapeutic outcome, animal studies report distinct yet often opposing roles for the α2A- and α2C-ARs on behavioral markers of mood and cognition, implying that non-selective α2-AR antagonism may compromise therapeutic utility both in terms of efficacy and side-effect liability. Recently, several highly selective α2C-AR antagonists have been identified that have allowed deeper investigation into the function and utility of the α2C-AR. ORM-13070 is a useful positron emission tomography ligand, ORM-10921 has demonstrated antipsychotic, antidepressant, and pro-cognitive actions in animals, while ORM-12741 is in clinical development for the treatment of cognitive dysfunction and neuropsychiatric symptoms in Alzheimer's disease. This review will emphasize the importance and relevance of the α2C-AR as a neuropsychiatric drug target in major depression, schizophrenia, and associated cognitive deficits. In addition, we will present new prospects and future directions of investigation.
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Affiliation(s)
- Madeleine Monique Uys
- Division of Pharmacology, Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa
| | | | - Brian Herbert Harvey
- Division of Pharmacology, Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa
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The effect of CA1 α2 adrenergic receptors on memory retention deficit induced by total sleep deprivation and the reversal of circadian rhythm in a rat model. Neurobiol Learn Mem 2016; 133:53-60. [DOI: 10.1016/j.nlm.2016.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 06/01/2016] [Accepted: 06/08/2016] [Indexed: 01/24/2023]
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12
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Jenkins PO, Mehta MA, Sharp DJ. Catecholamines and cognition after traumatic brain injury. Brain 2016; 139:2345-71. [PMID: 27256296 PMCID: PMC4995357 DOI: 10.1093/brain/aww128] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 04/20/2016] [Indexed: 01/11/2023] Open
Abstract
Cognitive problems are one of the main causes of ongoing disability after traumatic brain injury. The heterogeneity of the injuries sustained and the variability of the resulting cognitive deficits makes treating these problems difficult. Identifying the underlying pathology allows a targeted treatment approach aimed at cognitive enhancement. For example, damage to neuromodulatory neurotransmitter systems is common after traumatic brain injury and is an important cause of cognitive impairment. Here, we discuss the evidence implicating disruption of the catecholamines (dopamine and noradrenaline) and review the efficacy of catecholaminergic drugs in treating post-traumatic brain injury cognitive impairments. The response to these therapies is often variable, a likely consequence of the heterogeneous patterns of injury as well as a non-linear relationship between catecholamine levels and cognitive functions. This individual variability means that measuring the structure and function of a person’s catecholaminergic systems is likely to allow more refined therapy. Advanced structural and molecular imaging techniques offer the potential to identify disruption to the catecholaminergic systems and to provide a direct measure of catecholamine levels. In addition, measures of structural and functional connectivity can be used to identify common patterns of injury and to measure the functioning of brain ‘networks’ that are important for normal cognitive functioning. As the catecholamine systems modulate these cognitive networks, these measures could potentially be used to stratify treatment selection and monitor response to treatment in a more sophisticated manner.
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Affiliation(s)
- Peter O Jenkins
- 1 The Division of Brain Sciences, The Department of Medicine, Imperial College London, UK
| | - Mitul A Mehta
- 2 Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK
| | - David J Sharp
- 1 The Division of Brain Sciences, The Department of Medicine, Imperial College London, UK
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Berg T. α2-Adrenoreceptor Constraint of Catecholamine Release and Blood Pressure Is Enhanced in Female Spontaneously Hypertensive Rats. Front Neurosci 2016; 10:130. [PMID: 27065790 PMCID: PMC4812064 DOI: 10.3389/fnins.2016.00130] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Accepted: 03/15/2016] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED α2-adrenoceptors (α2AR) lower central sympathetic output and peripheral catecholamine release, and may therefore prevent sympathetic hyperactivity and hypertension. The α2AR are dysfunctional in male spontaneously hypertensive rats (SHR). Premenopausal females are less hypertensive than males. The purpose of this study was to test if this difference could be explained by functional α2AR in the female SHR. A 15-min tyramine-infusion was used to stimulate norepinephrine release through the re-uptake transporter, consequently preventing re-uptake. Presynaptic control of vesicular release will therefore be reflected as differences in overflow to plasma. The surgical trauma activates secretion of epinephrine, also subjected to α2AR auto-inhibition. Blood pressure was monitored through a femoral artery catheter and cardiac output by ascending aorta flow in 12-14 weeks-old (early hypertension) SHR and normotensive rats (WKY). Total peripheral vascular resistance (TPR) was calculated. Female SHR, unlike male, were close to normotensive. Pre-treatment with none-selective (clonidine) or non-A-selective (ST-91) α2AR agonist reduced, and none-selective α2AR antagonist (L-659,066) increased tyramine-induced norepinephrine overflow in female WKY and SHR. L-659,066 also increased secretion of epinephrine. The L-659,066-induced increase in catecholamine release was further enhanced by additional pre-treatment with ST-91 or angiotensin AT1 receptor antagonist (losartan) in SHR only. L-659,066 eliminated the tyramine-induced rise in TPR in both strains in female rats. CONCLUSION α2AR-mediated control of catecholamine release and vascular tension was therefore functional in female SHR, unlike that previously observed in male SHR. Functional α2AR is likely to have a protective function and may explain the lack of hypertension in the young female SHR.
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Affiliation(s)
- Torill Berg
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
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14
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Norepinephrine versus dopamine and their interaction in modulating synaptic function in the prefrontal cortex. Brain Res 2016; 1641:217-33. [PMID: 26790349 DOI: 10.1016/j.brainres.2016.01.005] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 12/16/2015] [Accepted: 01/05/2016] [Indexed: 01/11/2023]
Abstract
Among the neuromodulators that regulate prefrontal cortical circuit function, the catecholamine transmitters norepinephrine (NE) and dopamine (DA) stand out as powerful players in working memory and attention. Perturbation of either NE or DA signaling is implicated in the pathogenesis of several neuropsychiatric disorders, including attention deficit hyperactivity disorder (ADHD), post-traumatic stress disorder (PTSD), schizophrenia, and drug addiction. Although the precise mechanisms employed by NE and DA to cooperatively control prefrontal functions are not fully understood, emerging research indicates that both transmitters regulate electrical and biochemical aspects of neuronal function by modulating convergent ionic and synaptic signaling in the prefrontal cortex (PFC). This review summarizes previous studies that investigated the effects of both NE and DA on excitatory and inhibitory transmissions in the prefrontal cortical circuitry. Specifically, we focus on the functional interaction between NE and DA in prefrontal cortical local circuitry, synaptic integration, signaling pathways, and receptor properties. Although it is clear that both NE and DA innervate the PFC extensively and modulate synaptic function by activating distinctly different receptor subtypes and signaling pathways, it remains unclear how these two systems coordinate their actions to optimize PFC function for appropriate behavior. Throughout this review, we provide perspectives and highlight several critical topics for future studies. This article is part of a Special Issue entitled SI: Noradrenergic System.
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15
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Berridge CW, Spencer RC. Differential cognitive actions of norepinephrine a2 and a1 receptor signaling in the prefrontal cortex. Brain Res 2015; 1641:189-96. [PMID: 26592951 DOI: 10.1016/j.brainres.2015.11.024] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 10/06/2015] [Accepted: 11/12/2015] [Indexed: 10/22/2022]
Abstract
The prefrontal cortex (PFC) supports cognitive and behavioral processes that guide goal directed behavior. Moreover, dysregulated prefrontal cognitive dysfunction is associated with multiple psychiatric disorders. Norepinephrine (NE) signaling in the PFC is a critical modulator of prefrontal cognition and is targeted by a variety of drugs used to treat PFC-dependent cognitive dysfunction. Noradrenergic modulation of PFC-dependent cognition is complex, with concentration and receptor-specific actions that are likely dependent on neuronal activity state. Recent studies indicate that within the PFC, noradrenergic α1 and α2 receptors exert unique modulatory actions across distinct cognitive processes that allow for context-dependent modulation of cognition. Specifically, high affinity post-synaptic α2 receptors, engaged at moderate rates of NE release associated with moderate arousal levels, promote working memory. In contrast, lower affinity α1 receptors, engaged at higher rates of release associated with high arousal conditions (e.g. stress), impair working memory performance while promoting flexible attention. While these and other observations were initially interpreted to indicate high rates of NE release promotes the transition from focused to flexible/scanning attention, recent findings indicate that α1 receptors promote both focused and flexible attention. Collectively, these observations indicate that while α2 and α1 receptors in the PFC differentially modulate distinct cognitive processes, this cannot be simply ascribed to differential roles of these receptors in 'focused' vs. 'flexible' cognitive processes. Translationally, this information indicates that: (1) not all tests of prefrontal cognitive function may be appropriate for preclinical programs aimed at specific PFC-dependent disorders and (2) the treatment of specific PFC cognitive deficits may require the differential targeting of noradrenergic receptor subtypes. This article is part of a Special Issue entitled SI: Noradrenergic System.
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Affiliation(s)
- Craig W Berridge
- Department of Psychology, University of Wisconsin-Madison, Madison, WI 53706, United States.
| | - Robert C Spencer
- Department of Psychology, University of Wisconsin-Madison, Madison, WI 53706, United States
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16
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Noradrenergic signaling in the medial prefrontal cortex and amygdala differentially regulates vicarious trial-and-error in a spatial decision-making task. Behav Brain Res 2015; 297:104-11. [PMID: 26341318 DOI: 10.1016/j.bbr.2015.09.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 08/29/2015] [Accepted: 09/01/2015] [Indexed: 11/23/2022]
Abstract
In uncertain choice situations, we deliberately search and evaluate possible options before taking an action. Once we form a preference regarding the current situation, we take an action more automatically and with less deliberation. In rats, the deliberation process can be seen in vicarious trial-and-error behavior (VTE), which is a head-orienting behavior toward options at a choice point. Recent neurophysiological findings suggest that VTE reflects the rat's thinking about future options as deliberation, expectation, and planning when rats feel conflict. VTE occurs depending on the demand: an increase occurs during initial learning, and a decrease occurs with progression in learning. However, the brain circuit underlying the regulation of VTE has not been thoroughly examined. In situations in which VTE often appears, the medial prefrontal cortex (mPFC) and the amygdala (AMY) are crucial for learning and decision making. Our previous study reported that noradrenaline regulates VTE. Here, to investigate whether the mPFC and AMY are involved in regulation of VTE, we examined the effects of local injection of clonidine, an alpha2 adrenergic autoreceptor agonist, into either region in rats during VTE and choice behavior during a T-maze choice task. Injection of clonidine into either region impaired selection of the advantageous choice in the task. Furthermore, clonidine injection into the mPFC suppressed occurrence of VTE in the early phase of the task, whereas injection into the AMY inhibited the decrease in VTE in the later phase and thus maintained a high level of VTE throughout the task. These results suggest that the mPFC and AMY play a role in the increase and decrease in VTE, respectively, and that noradrenergic mechanisms mediate the dynamic regulation of VTE over experiences.
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Krishna V, Elias G, Sammartino F, Basha D, King NKK, Fasano A, Munhoz R, Kalia SK, Hodaie M, Venkatraghavan L, Lozano AM, Hutchison WD. The effect of dexmedetomidine on the firing properties of STN neurons in Parkinson's disease. Eur J Neurosci 2015; 42:2070-7. [DOI: 10.1111/ejn.13004] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 06/10/2015] [Accepted: 06/18/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Vibhor Krishna
- Division of Neurosurgery; Toronto Western Hospital; University of Toronto; 399 Bathurst Street Toronto ON M5T2S8 Canada
| | - Gavin Elias
- Division of Neurosurgery; Toronto Western Hospital; University of Toronto; 399 Bathurst Street Toronto ON M5T2S8 Canada
| | - Francesco Sammartino
- Division of Neurosurgery; Toronto Western Hospital; University of Toronto; 399 Bathurst Street Toronto ON M5T2S8 Canada
| | - Diellor Basha
- Department of Physiology; Toronto Western Hospital; University of Toronto; Toronto ON Canada
| | - Nicolas K. K. King
- Division of Neurosurgery; Toronto Western Hospital; University of Toronto; 399 Bathurst Street Toronto ON M5T2S8 Canada
| | - Alfonso Fasano
- Morton and Gloria Shulman Movement Disorders Centre and the Edmond J. Safra Program in Parkinson's Disease; Toronto Western Hospital; Toronto ON Canada
| | - Renato Munhoz
- Morton and Gloria Shulman Movement Disorders Centre and the Edmond J. Safra Program in Parkinson's Disease; Toronto Western Hospital; Toronto ON Canada
| | - Suneil K. Kalia
- Division of Neurosurgery; Toronto Western Hospital; University of Toronto; 399 Bathurst Street Toronto ON M5T2S8 Canada
| | - Mojgan Hodaie
- Division of Neurosurgery; Toronto Western Hospital; University of Toronto; 399 Bathurst Street Toronto ON M5T2S8 Canada
| | - Lashmi Venkatraghavan
- Department of Anesthesiology; Toronto Western Hospital; University of Toronto; Toronto ON Canada
| | - Andres M. Lozano
- Division of Neurosurgery; Toronto Western Hospital; University of Toronto; 399 Bathurst Street Toronto ON M5T2S8 Canada
| | - William D. Hutchison
- Department of Physiology; Toronto Western Hospital; University of Toronto; Toronto ON Canada
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18
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Fox H, Sofuoglu M, Sinha R. Guanfacine enhances inhibitory control and attentional shifting in early abstinent cocaine-dependent individuals. J Psychopharmacol 2015; 29:312-23. [PMID: 25567555 PMCID: PMC4432477 DOI: 10.1177/0269881114562464] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES Attenuation of adrenergic drive and cognitive enhancement, via stimulation of alpha2 pre- and post-synaptic receptors, may selectively enhance executive performance in early abstinent cocaine-dependent individuals. As these cognitive processes underpin important treatment-related behaviors, the alpha2 agonist, guanfacine HCl, may represent an effective pharmaco-therapeutic intervention. METHODS Twenty-five early abstinent cocaine-dependent individuals were administered a battery of neurocognitive tasks on entry into treatment (baseline) and again following 3 weeks of either placebo or guanfacine treatment (up to 3 mg). Tasks included: Stop Signal, Stroop, 3-Dimentional Intra-dimensional/Extra-dimensional (IDED) task, Spatial Working Memory (SWM), Paired Associates Learning (PAL), Verbal Fluency and the Rey Auditory Verbal Learning Test (RAVLT). RESULTS Compared with placebo, the guanfacine group demonstrated attenuated anxiety and negative affect as well as improved performance on selective executive tests. This included fewer directional errors on the stop signal task, fewer errors on the extra-dimensional shift component of the IDED task and better attentional switching during verbal fluency. Guanfacine did not improve strategic working memory or peripheral memory. CONCLUSION Guanfacine improves selective cognitive processes which may underlie salient treatment-related regulatory behaviors. Alpha2 agonists may therefore represent important agents for cocaine dependence.
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Affiliation(s)
- Helen Fox
- Department of Psychiatry, The Connecticut Mental Health Center, Yale University School of Medicine, New Haven, CT, USA
| | - Mehmet Sofuoglu
- Department of Psychiatry, VA Medical Center, Yale University School of Medicine, West Haven, CT, USA
| | - Rajita Sinha
- The Yale Stress Center, Yale University School of Medicine, Department of Psychiatry, New Haven, CT, USA
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19
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Lehto J, Hirvonen MM, Johansson J, Kemppainen J, Luoto P, Naukkarinen T, Oikonen V, Arponen E, Rouru J, Sallinen J, Scheinin H, Vuorilehto L, Finnema SJ, Halldin C, Rinne JO, Scheinin M. Validation of [(11) C]ORM-13070 as a PET tracer for alpha2c -adrenoceptors in the human brain. Synapse 2015; 69:172-81. [PMID: 25530024 DOI: 10.1002/syn.21798] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 12/03/2014] [Accepted: 12/10/2014] [Indexed: 12/24/2022]
Abstract
This study explored the use of the α2C -adrenoceptor PET tracer [(11) C]ORM-13070 to monitor α2C -AR occupancy in the human brain. The subtype-nonselective α2 -AR antagonist atipamezole was administered to eight healthy volunteer subjects to determine its efficacy and potency (Emax and EC50 ) at inhibiting tracer uptake. We also explored whether the tracer could reveal changes in the synaptic concentrations of endogenous noradrenaline in the brain, in response to several pharmacological and sensory challenge conditions. We assessed occupancy from the bound-to-free ratio measured during 5-30 min post injection. Based on extrapolation of one-site binding, the maximal extent of inhibition of striatal [(11) C]ORM-13070 uptake (Emax ) achievable by atipamezole was 78% (95% CI 69-87%) in the caudate nucleus and 65% (53-77%) in the putamen. The EC50 estimates of atipamezole (1.6 and 2.5 ng/ml, respectively) were in agreement with the drug's affinity to α2C -ARs. These findings represent clear support for the use of [(11) C]ORM-13070 for monitoring drug occupancy of α2C -ARs in the living human brain. Three of the employed noradrenaline challenges were associated with small, approximately 10-16% average reductions in tracer uptake in the dorsal striatum (atomoxetine, ketamine, and the cold pressor test; P < 0.05 for all), but insulin-induced hypoglycemia did not affect tracer uptake. The tracer is suitable for studying central nervous system receptor occupancy by α2C -AR ligands in human subjects. [(11) C]ORM-13070 also holds potential as a tool for in vivo monitoring of synaptic concentrations of noradrenaline, but this remains to be further evaluated in future studies.
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Affiliation(s)
- Jussi Lehto
- Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland; Clinical Research Services Turku CRST, Turku, Finland; Unit of Clinical Pharmacology, Turku University Hospital, Turku, Finland
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20
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Gasparik V, Greney H, Schann S, Feldman J, Fellmann L, Ehrhardt JD, Bousquet P. Synthesis and Biological Evaluation of 2-Aryliminopyrrolidines as Selective Ligands for I1 Imidazoline Receptors: Discovery of New Sympatho-Inhibitory Hypotensive Agents with Potential Beneficial Effects in Metabolic Syndrome. J Med Chem 2014; 58:878-87. [DOI: 10.1021/jm501456p] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Vincent Gasparik
- Laboratoire
de Neurobiologie
et Pharmacologie Cardiovasculaire, Faculté de Médecine,
EA 7296, Fédération de Médecine Translationnelle, Université de Strasbourg, 11 rue Humann, 67000 Strasbourg, France
| | - Hugues Greney
- Laboratoire
de Neurobiologie
et Pharmacologie Cardiovasculaire, Faculté de Médecine,
EA 7296, Fédération de Médecine Translationnelle, Université de Strasbourg, 11 rue Humann, 67000 Strasbourg, France
| | - Stephan Schann
- Laboratoire
de Neurobiologie
et Pharmacologie Cardiovasculaire, Faculté de Médecine,
EA 7296, Fédération de Médecine Translationnelle, Université de Strasbourg, 11 rue Humann, 67000 Strasbourg, France
| | - Josiane Feldman
- Laboratoire
de Neurobiologie
et Pharmacologie Cardiovasculaire, Faculté de Médecine,
EA 7296, Fédération de Médecine Translationnelle, Université de Strasbourg, 11 rue Humann, 67000 Strasbourg, France
| | - Lyne Fellmann
- Laboratoire
de Neurobiologie
et Pharmacologie Cardiovasculaire, Faculté de Médecine,
EA 7296, Fédération de Médecine Translationnelle, Université de Strasbourg, 11 rue Humann, 67000 Strasbourg, France
| | - Jean-Daniel Ehrhardt
- Laboratoire
de Neurobiologie
et Pharmacologie Cardiovasculaire, Faculté de Médecine,
EA 7296, Fédération de Médecine Translationnelle, Université de Strasbourg, 11 rue Humann, 67000 Strasbourg, France
| | - Pascal Bousquet
- Laboratoire
de Neurobiologie
et Pharmacologie Cardiovasculaire, Faculté de Médecine,
EA 7296, Fédération de Médecine Translationnelle, Université de Strasbourg, 11 rue Humann, 67000 Strasbourg, France
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21
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Fluorinated analogues of marsanidine, a highly α2-AR/imidazoline I1 binding site-selective hypotensive agent. Synthesis and biological activities. Eur J Med Chem 2014; 87:386-97. [PMID: 25282262 DOI: 10.1016/j.ejmech.2014.09.083] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 09/25/2014] [Accepted: 09/26/2014] [Indexed: 01/25/2023]
Abstract
The aim of these studies was to establish the influence of fluorination of the indazole ring on the pharmacological properties of two selective α2-adrenoceptor (α2-AR) agonists: 1-[(imidazolidin-2-yl)imino]-1H-indazole (marsanidine, A) and its methylene analogue 1-[(4,5-dihydro-1H-imidazol-2-yl)methyl]-1H-indazole (B). Introduction of fluorine into the indazole ring of A and B reduced both binding affinity and α2-AR/I1 imidazoline binding site selectivity. The most α2-AR-selective ligands were 6-fluoro-1-[(imidazolidin-2-yl)imino]-1H-indazole (6c) and 7-fluoro-1-[(imidazolidin-2-yl)imino]-1H-indazole (6d). The in vivo cardiovascular properties of fluorinated derivatives of A and B revealed that in both cases the C-7 fluorination leads to compounds with the highest hypotensive and bradycardic activities. The α2-AR partial agonist 6c was prepared as a potential lead compound for development of a radiotracer for PET imaging of brain α2-ARs.
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22
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Test–retest reliability of 11C-ORM-13070 in PET imaging of α2C-adrenoceptors in vivo in the human brain. Eur J Nucl Med Mol Imaging 2014; 42:120-7. [DOI: 10.1007/s00259-014-2899-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 08/13/2014] [Indexed: 10/24/2022]
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23
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Pawlowski M, Saraswathi S, Motawea HKB, Chotani MA, Kloczkowski A. In silico modeling of human α2C-adrenoreceptor interaction with filamin-2. PLoS One 2014; 9:e103099. [PMID: 25110951 PMCID: PMC4128582 DOI: 10.1371/journal.pone.0103099] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 06/19/2014] [Indexed: 12/19/2022] Open
Abstract
Vascular smooth muscle α2C-adrenoceptors (α2C-ARs) mediate vasoconstriction of small blood vessels, especially arterioles. Studies of endogenous receptors in human arteriolar smooth muscle cells (referred to as microVSM) and transiently transfected receptors in heterologous HEK293 cells show that the α2C-ARs are perinuclear receptors that translocate to the cell surface under cellular stress and elicit a biological response. Recent studies in microVSM unraveled a crucial role of Rap1A-Rho-ROCK-F-actin pathways in receptor translocation, and identified protein-protein interaction of α2C-ARs with the actin binding protein filamin-2 as an essential step in the process. To better understand the molecular nature and specificity of this interaction, in this study, we constructed comparative models of human α2C-AR and human filamin-2 proteins. Finally, we performed in silico protein-protein docking to provide a structural platform for the investigation of human α2C-AR and filamin-2 interactions. We found that electrostatic interactions seem to play a key role in this complex formation which manifests in interactions between the C-terminal arginines of α2C-ARs (particularly R454 and R456) and negatively charged residues from filamin-2 region between residues 1979 and 2206. Phylogenetic and sequence analysis showed that these interactions have evolved in warm-blooded animals.
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Affiliation(s)
- Marcin Pawlowski
- Battelle Center for Mathematical Medicine, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Saras Saraswathi
- Battelle Center for Mathematical Medicine, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Hanaa K. B. Motawea
- Center for Cardiovascular and Pulmonary Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pharmacology & Toxicology, Helwan University, Helwan, Egypt
| | - Maqsood A. Chotani
- Center for Cardiovascular and Pulmonary Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
| | - Andrzej Kloczkowski
- Battelle Center for Mathematical Medicine, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
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Kawaura K, Karasawa JI, Chaki S, Hikichi H. Stimulation of postsynapse adrenergic α2A receptor improves attention/cognition performance in an animal model of attention deficit hyperactivity disorder. Behav Brain Res 2014; 270:349-56. [PMID: 24882610 DOI: 10.1016/j.bbr.2014.05.044] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 05/20/2014] [Accepted: 05/21/2014] [Indexed: 10/25/2022]
Abstract
A 5-trial inhibitory avoidance test using spontaneously hypertensive rat (SHR) pups has been used as an animal model of attention deficit hyperactivity disorder (ADHD). However, the roles of noradrenergic systems, which are involved in the pathophysiology of ADHD, have not been investigated in this model. In the present study, the effects of adrenergic α2 receptor stimulation, which has been an effective treatment for ADHD, on attention/cognition performance were investigated in this model. Moreover, neuronal mechanisms mediated through adrenergic α2 receptors were investigated. We evaluated the effects of both clonidine, a non-selective adrenergic α2 receptor agonist, and guanfacine, a selective adrenergic α2A receptor agonist, using a 5-trial inhibitory avoidance test with SHR pups. Juvenile SHR exhibited a shorter transfer latency, compared with juvenile Wistar Kyoto (WKY) rats. Both clonidine and guanfacine significantly prolonged the transfer latency of juvenile SHR. The effects of clonidine and guanfacine were significantly blocked by pretreatment with an adrenergic α2A receptor antagonist. In contrast, the effect of clonidine was not attenuated by pretreatment with an adrenergic α2B receptor antagonist, or an adrenergic α2C receptor antagonist, while it was attenuated by a non-selective adrenergic α2 receptor antagonist. Furthermore, the effects of neither clonidine nor guanfacine were blocked by pretreatment with a selective noradrenergic neurotoxin. These results suggest that the stimulation of the adrenergic α2A receptor improves the attention/cognition performance of juvenile SHR in the 5-trial inhibitory avoidance test and that postsynaptic, rather than presynaptic, adrenergic α2A receptor is involved in this effect.
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Affiliation(s)
- Kazuaki Kawaura
- Pharmacology I, Pharmacology Laboratories, Taisho Pharmaceutical Co., Ltd., 1-403 Yoshino-cho, Kita-ku, Saitama, Saitama 331-9530, Japan
| | - Jun-ichi Karasawa
- Pharmacology I, Pharmacology Laboratories, Taisho Pharmaceutical Co., Ltd., 1-403 Yoshino-cho, Kita-ku, Saitama, Saitama 331-9530, Japan
| | - Shigeyuki Chaki
- Pharmacology I, Pharmacology Laboratories, Taisho Pharmaceutical Co., Ltd., 1-403 Yoshino-cho, Kita-ku, Saitama, Saitama 331-9530, Japan
| | - Hirohiko Hikichi
- Pharmacology I, Pharmacology Laboratories, Taisho Pharmaceutical Co., Ltd., 1-403 Yoshino-cho, Kita-ku, Saitama, Saitama 331-9530, Japan.
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25
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Kim JO, Jeon YJ, Kim OJ, Oh SH, Kim HS, Shin BS, Oh D, Kim EJ, Cho YK, Kim NK. Association between common genetic variants of α2A-, α2B- and α2C-adrenoceptors and the risk of silent brain infarction. Mol Med Rep 2014; 9:2459-66. [PMID: 24676565 DOI: 10.3892/mmr.2014.2072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 03/04/2014] [Indexed: 11/06/2022] Open
Abstract
Silent brain infarction (SBI) is an asymptomatic cerebrovascular disorder. The aim of the present study was to investigate the association between adrenoceptor-α2 (ADRA2) gene polymorphisms and SBI. A total of 361 patients with SBI and 467 healthy control subjects were examined. The polymerase chain reaction was performed to genotype the ADRA2A 1780G>A, ADRA2B 301-303 insertion/deletion (I/D) and ADRA2C 322-325I/D polymorphisms. The frequency of the ADRA2C 322-325I/D polymorphism was significantly different between patients with SBI and control subjects. When interaction analyses were performed for vascular risk factors, the ADRA2C 322-325ID genotype increased the risk for SBI in the presence of hypertension and elevated plasma homocysteine levels. The ADRA2C 322-325ID genotype and plasma homocysteine levels showed a significant synergistic effect for SBI. In addition, the ADRA2A 1780AA genotype was associated with elevated plasma homocysteine levels. Although further analysis of the association between ADRA2 polymorphisms and clinical risk factors of SBI is required, the present study of a limited set of SBI risk factors with ADRA2 polymorphisms provides the first evidence of the involvement of ADRA2 gene family members in the development of SBI. Further studies using larger and more heterogeneous populations are required to validate the association of ADRA2 polymorphisms with SBI.
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Affiliation(s)
- Jung O Kim
- Institute for Clinical Research, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Gyeonggi-do 463-712, Republic of Korea
| | - Young Joo Jeon
- Institute for Clinical Research, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Gyeonggi-do 463-712, Republic of Korea
| | - Ok Joon Kim
- Department of Neurology, CHA Bundang Medical Center, CHA University, Seongnam, Gyeonggi-do 463-712, Republic of Korea
| | - Seung Hun Oh
- Department of Neurology, CHA Bundang Medical Center, CHA University, Seongnam, Gyeonggi-do 463-712, Republic of Korea
| | - Hyun Sook Kim
- Department of Neurology, CHA Bundang Medical Center, CHA University, Seongnam, Gyeonggi-do 463-712, Republic of Korea
| | - Byoung Soo Shin
- Department of Neurology, Chonbuk National University Hospital and Medical School, Jeonju 561-712, Republic of Korea
| | - Doyeun Oh
- Institute for Clinical Research, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Gyeonggi-do 463-712, Republic of Korea
| | - Eo Jin Kim
- Department of Medicine, College of Medicine, Chung-Ang University Seoul 156-756, Republic of Korea
| | - Yun Kyung Cho
- Department of Internal Medicine, CHA Gangnam Medical Center, CHA University, Seoul 135-913, Republic of Korea
| | - Nam Keun Kim
- Institute for Clinical Research, CHA Bundang Medical Center, CHA University School of Medicine, Seongnam, Gyeonggi-do 463-712, Republic of Korea
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Marketou ME, Kintsurashvili E, Androulakis NE, Kontaraki J, Alexandrakis MG, Gavras I, Vardas PE, Gavras H. Blockade of platelet alpha2B-adrenergic receptors: A novel antiaggregant mechanism. Int J Cardiol 2013; 168:2561-6. [DOI: 10.1016/j.ijcard.2013.03.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 02/07/2013] [Accepted: 03/17/2013] [Indexed: 10/26/2022]
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Cai J, Li J, Mao Y, Bai X, Xu L, Wang H. Immunohistochemical Localization of α2-Adrenergic Receptors in the Neonatal Rat Cochlea and the Vestibular Labyrinth. J Mol Neurosci 2013; 51:1010-20. [DOI: 10.1007/s12031-013-0089-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2013] [Accepted: 07/29/2013] [Indexed: 12/17/2022]
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Sallee F, Connor DF, Newcorn JH. A review of the rationale and clinical utilization of α2-adrenoceptor agonists for the treatment of attention-deficit/hyperactivity and related disorders. J Child Adolesc Psychopharmacol 2013; 23:308-19. [PMID: 23782125 DOI: 10.1089/cap.2013.0028] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Interest in the potential role for the α2-adrenoceptor agonists clonidine and guanfacine as treatments for attention-deficit/hyperactivity disorder (ADHD) has driven additional clinical studies as well as development of new formulations of these agents. This article reviews the published data that supported United States Food and Drug Administration approval and subsequent clinical use of α2-adrenoceptor agonists in the treatment of ADHD, and identifies promising directions for future research. METHODS Electronic searches were performed in PubMed through October 2012 using the base terms ADHD or attention deficit hyperactivity disorder and alpha agonists, as well as the following limits: humans, clinical trial, meta-analysis, practice guideline, randomized controlled trial, review, English. The electronic searches were complemented with reference lists from the articles retrieved by informal search of the literature, producing a qualitative review of published, pertinent drug-class preclinical and clinical data. Articles were selected for greater exposition based on hierarchy of evidence (e.g., randomized controlled trials), relevance, and quality of individual studies, as well as generalizability to clinical practice. RESULTS Results of clinical studies of immediate-release and extended-release formulations of α2-adrenoceptor agonists and basic science investigations of cognitive effects of these drugs are discussed. Studies of both clonidine and guanfacine extended-release formulations as monotherapy and adjunctive therapy with psychostimulants for the treatment of ADHD are also reviewed. CONCLUSIONS Large, randomized, placebo-controlled clinical trials support the efficacy and safety of α2-adrenoceptor agonists as monotherapy and adjunctive therapy with psychostimulants for the symptomatic treatment of ADHD. Future research could reveal whether there are cognitive benefits associated with this drug class and thus further define the role of α2-adrenoceptor agonists in the treatment of ADHD.
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Affiliation(s)
- Floyd Sallee
- Department of Psychiatry, University of Cincinnati, Cincinnati, OH 45219, USA.
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Jafari-Sabet M, Banafshe HR, Khodadadnejad MA. Modulation of muscimol state-dependent memory by α2-adrenoceptors of the dorsal hippocampal area. Eur J Pharmacol 2013; 710:92-9. [PMID: 23603244 DOI: 10.1016/j.ejphar.2013.03.046] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 03/27/2013] [Accepted: 03/28/2013] [Indexed: 11/30/2022]
Abstract
In the present study, the effects of bilateral intra-dorsal hippocampal (intra-CA1) injections of α2-adrenoceptor agonist and antagonist, on muscimol state-dependent memory were examined in mice. A single-trial step-down passive avoidance task was used for the assessment of memory retention in adult male NMRI mice. Administration of muscimol (0.1 μg/mouse, intra-CA1) 15 min before training or testing induced impairment of memory retention. Injection of the same dose of the drug 15 min before testing restored memory retention impaired under pre-training muscimol influence. Pre-test intra-CA1 administration of the α2-adrenoceptor agonist clonidine (0.5 and 1 μg/mouse) impaired memory retention, although the low dose of the drug (0.25 μg/mouse) did not affect memory retention. Pre-test intra-CA1 administration of the α2-adrenoceptor antagonist yohimbine (1 and 2 μg/mouse) improved memory retention, although the low dose of the drug (0.5 μg/mouse) did not affect memory retention. In other series of experiments, pre-test co-administration of certain doses of clonidine (0.125 and 0.25 μg/mouse, intra-CA1), doses which were ineffective when given alone, and muscimol (0.1 μg/mouse, intra-CA1) significantly inhibited muscimol state-dependent memory. Pre-test intra-CA1 administration of certain doses of yohimbine (0.25 and 0.5 μg/mouse), doses which were ineffective when given alone, improved pre-training muscimol (0.1 μg/mouse)-induced retrieval impairment. Moreover, pre-test co-administration of yohimbine (0.25 and 0.5 μg/mouse, intra-CA1) and muscimol (0.025 μg/mouse, intra-CA1), an ineffective dose, significantly restored the retrieval and induced muscimol state-dependent memory. It may be concluded that the α2-adrenoceptors of the dorsal hippocampal area play an important role in muscimol state-dependent memory.
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Affiliation(s)
- Majid Jafari-Sabet
- Department of Pharmacology, School of Medicine, AJA University of Medical Sciences, Tehran, Iran.
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Differential Involvement of Central and Peripheral α2 Adrenoreceptors in the Antinociception Induced by Aerobic and Resistance Exercise. Anesth Analg 2013; 116:703-11. [DOI: 10.1213/ane.0b013e31827ab6e4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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31
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Cai J, Li J, Liu W, Han Y, Wang H. Alpha2-adrenergic receptors in spiral ganglion neurons may mediate protective effects of brimonidine and yohimbine against glutamate and hydrogen peroxide toxicity. Neuroscience 2013; 228:23-35. [DOI: 10.1016/j.neuroscience.2012.10.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 09/29/2012] [Accepted: 10/01/2012] [Indexed: 10/27/2022]
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Oh SH, Min KT, Jeon YJ, Kim MH, Kim OJ, Shin BS, Oh D, Kim NK. Association between common genetic variants of α2A-, α2B-, and α2C-adrenergic receptors and ischemic stroke. Clin Neurol Neurosurg 2013; 115:26-31. [DOI: 10.1016/j.clineuro.2012.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 03/02/2012] [Accepted: 04/01/2012] [Indexed: 11/29/2022]
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Gamache K, Pitman RK, Nader K. Preclinical evaluation of reconsolidation blockade by clonidine as a potential novel treatment for posttraumatic stress disorder. Neuropsychopharmacology 2012; 37:2789-96. [PMID: 22871915 PMCID: PMC3499710 DOI: 10.1038/npp.2012.145] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exposure to traumatic events can lead to posttraumatic stress disorder (PTSD). Current PTSD treatments typically only produce partial improvement. Hence, there is a need for preclinical research to identify new candidate drugs and to develop novel therapeutic approaches. Animal studies have indicated that fear memories can be weakened by blocking restabilization after retrieval, a process known as reconsolidation. Furthermore, evidence suggests that there are important alterations of the noradrenergic system in PTSD, and hence it may be of interest to study drugs that target this pathway. Here, we investigated the efficacy of clonidine, an α₂-adrenoreceptor agonist, to block reconsolidation in an animal model of persistent traumatic memories. Using an auditory fear conditioning paradigm in rats, we tested the efficacy of clonidine to weaken fear memory retention when administered systemically after retrieval. We evaluated dosage, number of treatments, and specificity in reconsolidation blockade. We found that postretrieval administration of clonidine disrupts fear-related memories in a dose-dependent manner and that two treatments are sufficient for maximal memory impairment. Furthermore, we determined that this effect is long lasting and specific to reconsolidation processes as shown by the selectivity to affect reactivated memories and the absence of spontaneous recovery and of postreactivation short-term memory impairment. Our results demonstrate the efficacy of systemic administration of clonidine following retrieval to persistently disrupt fear memory retention through reconsolidation blockade. This study provides important preclinical parameters for future therapeutic strategies involving clonidine to block reconsolidation as a novel treatment for PTSD symptoms.
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Affiliation(s)
- Karine Gamache
- Department of Psychology, McGill University, Montreal, QC, Canada.
| | - Roger K Pitman
- Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Karim Nader
- Department of Psychology, McGill University, Montreal, QC, Canada
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Agassandian K, Shan Z, Raizada M, Sved AF, Card JP. C1 catecholamine neurons form local circuit synaptic connections within the rostroventrolateral medulla of rat. Neuroscience 2012; 227:247-59. [PMID: 23041757 DOI: 10.1016/j.neuroscience.2012.09.049] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 09/20/2012] [Accepted: 09/20/2012] [Indexed: 02/07/2023]
Abstract
C1 catecholamine neurons reside within the rostroventrolateral medulla (RVLM), an area that plays an integral role in blood pressure regulation through reticulospinal projections to sympathetic preganglionic neurons in the thoracic spinal cord. In a previous investigation we mapped the efferent projections of C1 neurons, documenting supraspinal projections to cell groups in the preautonomic network that contribute to the control of cardiovascular function. Light microscopic study also revealed putative local circuit connections within RVLM. In this investigation we tested the hypothesis that RVLM C1 neurons elaborate a local circuit synaptic network that permits communication between C1 neurons giving rise to supraspinal and reticulospinal projections. A replication defective lentivirus vector that expresses enhanced green fluorescent protein (EGFP) under the control of a synthetic dopamine beta hydroxylase (DβH) promoter was used to label C1 neurons and their processes. Confocal fluorescence microscopy demonstrated thin varicose axons immunopositive for EGFP and tyrosine hydroxylase that formed close appositions to C1 somata and dendrites throughout the rostrocaudal extent of the C1 area. Dual-labeled electron microscopic analysis revealed axosomatic, axodendritic and axospinous synaptic contacts with C1 and non-C1 neurons with a distribution recapitulating that observed in the light microscopic analysis. Labeled boutons were large, contained light axoplasm, lucent spherical vesicles, and formed asymmetric synaptic contacts. Collectively these data demonstrate that C1 neurons form a synaptic network within the C1 area that may function to coordinate activity among projection-specific subpopulations of neurons. The data also suggest that the boundaries of RVLM should be defined on the basis of function criteria rather than the C1 phenotype of neurons.
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Affiliation(s)
- K Agassandian
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, United States
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Abstract
Stress is known to activate distinct neuronal circuits in the brain and induce multiple changes on the cellular level, including alterations in neuronal structures. On the basis of clinical observations that stress often precipitates a depressive disease, chronic psychosocial stress serves as an experimental model to evaluate the cellular and molecular alterations associated with the consequences of major depression. Antidepressants are presently believed to exert their primary biochemical effects by readjusting aberrant intrasynaptic concentrations of neurotransmitters, such as serotonin or noradrenaline, suggesting that imbalances viihin the monoaminergic systems contribute to the disorder (monoaminergic hypothesis of depression). Here, we reviev the results that comprise our understanding of stressful experience on cellular processes, with particular focus on the monoaminergic systems and structural changes within brain target areas of monoaminergic neurons.
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Affiliation(s)
- Eberhard Fuchs
- Clinical Neurobiology Laboratory, German Primate Center, Göttingen, Germany
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36
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Attention deficit hyperactivity disorder. Transl Neurosci 2012. [DOI: 10.1017/cbo9780511980053.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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37
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Characterization of α2B-adrenoceptor ligand binding in the presence of Muscarinic toxin α and delineation of structural features of receptor binding selectivity. Eur J Pharmacol 2012; 683:63-70. [DOI: 10.1016/j.ejphar.2012.03.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 03/09/2012] [Accepted: 03/09/2012] [Indexed: 11/24/2022]
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38
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Alpha2C-adrenoceptors play a prominent role in sympathetic constriction of porcine pulmonary arteries. Naunyn Schmiedebergs Arch Pharmacol 2012; 385:595-603. [DOI: 10.1007/s00210-012-0741-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 02/10/2012] [Indexed: 12/28/2022]
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Laurila JMM, Wissel G, Xhaard H, Ruuskanen JO, Johnson MS, Scheinin M. Involvement of the first transmembrane segment of human α(2) -adrenoceptors in the subtype-selective binding of chlorpromazine, spiperone and spiroxatrine. Br J Pharmacol 2012; 164:1558-72. [PMID: 21649638 DOI: 10.1111/j.1476-5381.2011.01520.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Some large antagonist ligands (ARC239, chlorpromazine, prazosin, spiperone, spiroxatrine) bind to the human α(2A) -adrenoceptor with 10- to 100-fold lower affinity than to the α(2B)- and α(2C)-adrenoceptor subtypes. Previous mutagenesis studies have not explained this subtype selectivity. EXPERIMENTAL APPROACH The possible involvement of the extracellular amino terminus and transmembrane domain 1 (TM1) in subtype selectivity was elucidated with eight chimaeric receptors: six where TM1 and the N-terminus were exchanged between the α(2)-adrenoceptor subtypes and two where only TM1 was exchanged. Receptors were expressed in CHO cells and tested for ligand binding with nine chemically diverse antagonist ligands. For purposes of interpretation, molecular models of the three human α(2)-adrenoceptors were constructed based on the β(2)-adrenoceptor crystal structure. KEY RESULTS The affinities of three antagonists (spiperone, spiroxatrine and chlorpromazine) were significantly improved by TM1 substitutions of the α(2A)-adrenoceptor, but reciprocal effects were not seen for chimaeric receptors based on α(2B)- and α(2C)-adrenoceptors. Molecular docking of these ligands suggested that binding occurs in the orthosteric ligand binding pocket. CONCLUSIONS AND IMPLICATIONS TM1 is involved in determining the low affinity of some antagonist ligands at the human α(2A)-adrenoceptor. The exact mechanism is not known, but the position of TM1 at a large distance from the binding pocket indicates that TM1 does not participate in specific side-chain interactions with amino acids within the binding pocket of the receptor or with ligands bound therein. Instead, molecular models suggest that TM1 has indirect conformational effects related to the charge distribution or overall shape of the binding pocket.
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Affiliation(s)
- J M M Laurila
- Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland
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Jnoff E, Christophe B, Collart P, Coloretti F, Debeuckelaere A, De Ryck M, Fuks B, Genicot C, Gillard M, Guyaux M, Price N, Vandergeten MC, Vermeiren C. Discovery of Selective Alpha2CAdrenergic Receptor Agonists. ChemMedChem 2012; 7:385-90. [DOI: 10.1002/cmdc.201100528] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Indexed: 11/09/2022]
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Sanders JD, Happe HK, Bylund DB, Murrin LC. Changes in postnatal norepinephrine alter alpha-2 adrenergic receptor development. Neuroscience 2011; 192:761-72. [PMID: 21742019 PMCID: PMC3166411 DOI: 10.1016/j.neuroscience.2011.06.045] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 05/25/2011] [Accepted: 06/15/2011] [Indexed: 10/18/2022]
Abstract
Alpha-2 adrenergic receptors (A2AR) regulate multiple brain functions and are enriched in developing brain. Studies demonstrate norepinephrine (NE) plays a role in regulating brain maturation, suggesting it is important in A2AR development. To investigate this we employed models of NE absence and excess during brain development. For decreases in NE we used N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride (DSP4), a specific noradrenergic neurotoxin. Increased noradrenergic terminal density was produced by methylazoxymethanol acetate (MAM) treatment. A2AR density was assayed with [(3)H]RX821002 autoradiography. DSP4 lesions on postnatal day (PND) 3 produce A2AR decreases in many regions by PND 5. A2AR recover to control levels by PND 15 and 25 and there is no further change in total receptor density. We also assayed A2AR in brains lesioned with DSP4 on PND 13, 23, 33 and 43 and harvested 22 days post-lesion. A2AR levels remain similar to control at each of these time points. We examined A2AR functionality and high affinity state with epinephrine-stimulated [(35)S]GTPγS and [(125)I]p-iodoclonidine autoradiography, respectively. On PND 25, control animals and animals lesioned with DSP4 on PND 3 have similar levels of [(35)S]GTPγS incorporation and no change in high affinity state. This is in contrast to increases in A2AR high affinity state produced by DSP4 lesions of mature brain. We next investigated A2AR response to increases in norepinephrine levels produced by MAM. In contrast to DSP4 lesions, increasing NE results in a large increase in A2AR. Animals treated with MAM on gestational day 14 had cortical [(3)H]RX821002 binding 100-200% greater than controls on PND 25, 35, 45, 55 and 65. These data indicate that NE regulation of A2AR differs in developing and mature brain and support the idea that NE regulates A2AR development and this has long term effects on A2AR function.
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Affiliation(s)
- Jeff D. Sanders
- Department of Pharmacology and Experimental Neuroscience, 985800 Nebraska Medical Center, Omaha, NE 68198-5800
| | - H. Kevin Happe
- Department of Psychiatry, Creighton University School of Medicine, Omaha, NE 68131
| | - David B. Bylund
- Department of Pharmacology and Experimental Neuroscience, 985800 Nebraska Medical Center, Omaha, NE 68198-5800
| | - L. Charles Murrin
- Department of Pharmacology and Experimental Neuroscience, 985800 Nebraska Medical Center, Omaha, NE 68198-5800
- Department of Neurological Sciences, 982045 Nebraska Medical Center, Omaha, NE 68198-2045
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Quaglia W, Del Bello F, Giannella M, Piergentili A, Pigini M. α2C-adrenoceptor modulators: a patent review. Expert Opin Ther Pat 2011; 21:455-81. [PMID: 21413828 DOI: 10.1517/13543776.2011.565333] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION α2-Adrenoceptors (α2-ARs) are membrane proteins belonging to the superfamily of GPCRs. Detailed studies have shown three different subtypes, namely α2A, α2B and α2C. Although numerous α2-AR ligands exist, only a small set of compounds have shown even a degree of selectivity among the three α2-AR subtypes. Moreover, these compounds suffer from binding to receptor sites outside the α2-AR subfamily. Efforts made to understand the biological significance of each α2-AR subtype have greatly been assisted by genetically engineered mice. The main results obtained suggest that α2C-AR stimulation may represent a therapeutic strategy to get an analgesic response with reduced sedative effects and undesirable changes in blood pressure due to α2A-AR activation. AREAS COVERED This review summarizes the patent literature about the development of α2C-AR modulators from 2000 to early 2010 and their therapeutic effects evoked by the interaction with this receptor subtype. EXPERT OPINION Over 90 patents have been deposited in the last 10 years regarding different methods of α2C-AR modulation (use of agonists or antagonists, nucleic acids and polypeptides) for diagnosis, prognosis and treatment of disorders involving this receptor. Nevertheless, despite the numerous published patents, ligands highly selective for the α2C-AR subtype, which continues to be enigmatic, are lacking.
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Affiliation(s)
- Wilma Quaglia
- University of Camerino, Via S Agostino 1 Camerino, Italy.
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Chotani MA, Flavahan NA. Intracellular α(2C)-adrenoceptors: storage depot, stunted development or signaling domain? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1495-503. [PMID: 21605601 DOI: 10.1016/j.bbamcr.2011.05.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 05/03/2011] [Accepted: 05/06/2011] [Indexed: 12/11/2022]
Abstract
G-protein coupled receptors (GPCRs) are generally considered to function as cell surface signaling structures that respond to extracellular mediators, many of which do not readily access the cell's interior. Indeed, most GPCRs are preferentially targeted to the plasma membrane. However, some receptors, including α(2C)-Adrenoceptors, challenge conventional concepts of GPCR activity by being preferentially retained and localized within intracellular organelles. This review will address the issues associated with this unusual GPCR localization and discuss whether it represents a novel sub-cellular niche for GPCR signaling, whether these receptors are being stored for rapid deployment to the cell surface, or whether they represent immature or incomplete receptor systems.
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Affiliation(s)
- Maqsood A Chotani
- Center for Cardiovascular and Pulmonary Research, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
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44
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Wang Y, Liu J, Gui Z, Ali U, Fan L, Hou C, Wang T, Chen L, Li Q. α2-Adrenoceptor regulates the spontaneous and the GABA/glutamate modulated firing activity of the rat medial prefrontal cortex pyramidal neurons. Neuroscience 2011; 182:193-202. [DOI: 10.1016/j.neuroscience.2011.03.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2010] [Revised: 03/05/2011] [Accepted: 03/08/2011] [Indexed: 11/25/2022]
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45
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Yoon M, Huang L, Choi J, Lee H, Kim W, Kim C. Antinociceptive effect of intrathecal ginsenosides through α-2 adrenoceptors in the formalin test of rats. Br J Anaesth 2011; 106:371-9. [DOI: 10.1093/bja/aeq367] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Gilsbach R, Albarrán-Juárez J, Hein L. Pre- versus Postsynaptic Signaling by α2-Adrenoceptors. CURRENT TOPICS IN MEMBRANES 2011; 67:139-60. [DOI: 10.1016/b978-0-12-384921-2.00007-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Filipeanu CM, de Vries R, Danser AHJ, Kapusta DR. Modulation of α(2C) adrenergic receptor temperature-sensitive trafficking by HSP90. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:346-57. [PMID: 21145921 DOI: 10.1016/j.bbamcr.2010.11.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2010] [Revised: 11/23/2010] [Accepted: 11/30/2010] [Indexed: 11/18/2022]
Abstract
Decreasing the temperature to 30°C is accompanied by significant enhancement of α(2C)-AR plasma membrane levels in several cell lines with fibroblast phenotype, as demonstrated by radioligand binding in intact cells. No changes were observed on the effects of low-temperature after blocking receptor internalization in α(2C)-AR transfected HEK293T cells. In contrast, two pharmacological chaperones, dimethyl sulfoxide and glycerol, increased the cell surface receptor levels at 37°C, but not at 30°C. Further, at 37°C α(2C)-AR is co-localized with endoplasmic reticulum markers, but not with the lysosomal markers. Treatment with three distinct HSP90 inhibitors, radicicol, macbecin and 17-DMAG significantly enhanced α(2C)-AR cell surface levels at 37°C, but these inhibitors had no effect at 30°C. Similar results were obtained after decreasing the HSP90 cellular levels using specific siRNA. Co-immunoprecipitation experiments demonstrated that α(2C)-AR interacts with HSP90 and this interaction is decreased at 30°C. The contractile response to endogenous α(2C)-AR stimulation in rat tail artery was also enhanced at reduced temperature. Similar to HEK293T cells, HSP90 inhibition increased the α(2C)-AR contractile effects only at 37°C. Moreover, exposure to low-temperature of vascular smooth muscle cells from rat tail artery decreased the cellular levels of HSP90, but did not change HSP70 levels. These data demonstrate that exposure to low-temperature augments the α(2C)-AR transport to the plasma membrane by releasing the inhibitory activity of HSP90 on the receptor traffic, findings which may have clinical relevance for the diagnostic and treatment of Raynaud Phenomenon.
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MESH Headings
- Animals
- Arteries
- Benzoquinones/pharmacology
- Cell Membrane/metabolism
- Cells, Cultured
- Enzyme Inhibitors/pharmacology
- HSP90 Heat-Shock Proteins/physiology
- Humans
- Kidney/cytology
- Kidney/metabolism
- Lactams, Macrocyclic/pharmacology
- Macrolides/pharmacology
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Protein Transport
- Protein-Tyrosine Kinases/antagonists & inhibitors
- RNA, Small Interfering/genetics
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, alpha-2/metabolism
- Subcellular Fractions
- Temperature
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Affiliation(s)
- Catalin M Filipeanu
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido Street, New Orleans, Louisiana, LA-70112, USA.
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48
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Kosugi T, Mizuta K, Fujita T, Nakashima M, Kumamoto E. High concentrations of dexmedetomidine inhibit compound action potentials in frog sciatic nerves without alpha(2) adrenoceptor activation. Br J Pharmacol 2010; 160:1662-76. [PMID: 20649570 DOI: 10.1111/j.1476-5381.2010.00833.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Dexmedetomidine, an alpha(2)-adrenoceptor agonist, exhibits anti-nociceptive actions at the spinal cord and enhances the effect of local anaesthetics in the peripheral nervous system. Although the latter action may be attributed in part to inhibition of nerve conduction produced by dexmedetomidine, this has not been fully examined yet. EXPERIMENTAL APPROACH We examined the effects of various adrenoceptor agonists including dexmedetomidine, and tetracaine, a local anaesthetic, on compound action potentials (CAPs) recorded from the frog sciatic nerve, using the air-gap method. KEY RESULTS Dexmedetomidine reversibly and concentration-dependently reduced the peak amplitude of CAPs (IC(50)= 0.40 mmol x L(-1)). This action was not antagonized by two alpha(2)-adrenoceptor antagonists, yohimbine and atipamezole; the latter antagonist itself reduced CAP peak amplitude. Clonidine and oxymetazoline, two other alpha(2)-adrenoceptor agonists, also inhibited CAPs; the maximum effect of clonidine was only 20%, while oxymetazoline was less potent (IC(50)= 1.5 mmol x L(-1)) than dexmedetomidine. On the other hand, (+/-)-adrenaline, (+/-)-noradrenaline, alpha(1)-adrenoceptor agonist (-)-phenylephrine and beta-adrenoceptor agonist (-)-isoprenaline (each 1 mmol x L(-1)) had no effect on CAPs. Tetracaine reversibly reduced CAP peak amplitude (IC(50) of 0.014 mmol x L(-1)). CONCLUSIONS AND IMPLICATIONS Dexmedetomidine reduced CAP peak amplitude without alpha(2)-adrenoceptor activation (at concentrations >1000-fold higher than those used as alpha(2) adrenoceptor agonist), with a lower potency than tetracaine. CAPs were inhibited by other alpha(2) adrenoceptor agonists, oxymetazoline and clonidine, and also an alpha(2) adrenoceptor antagonist atipamezole. Thus, some drugs acting on alpha(2) adrenoceptors are able to block nerve conduction.
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49
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Vacher B, Funes P, Chopin P, Cussac D, Heusler P, Tourette A, Marien M. Rigid analogues of the α2-adrenergic blocker atipamezole: small changes, big consequences. J Med Chem 2010; 53:6986-95. [PMID: 20809632 DOI: 10.1021/jm1006269] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the discovery of a new family of α(2) adrenergic receptor antagonists derived from atipamezole. Affinities of the compounds at human α(2) and α(1b) receptors as well as their functional activities at hα(2A) receptors were determined in competition binding and G-protein activation assays, respectively. Central α(2) antagonist activities were confirmed in mice after oral administration. Further studies on a selected example: (+)-4-(1a,6-dihydro-1H-cyclopropa[a]inden-6a-yl)-1H-imidazole, (+)-1 (F 14805), were undertaken to probe the potential of the series. On the one hand, (+)-1 increased the release of noradrenaline in mouse frontal cortex following acute systemic administration, the magnitude of this effect being much larger than that obtained with reference agents. On the other, (+)-1 produced minimal cardiovascular effects in intact, anesthetized rat, a surprising outcome that might be explained by its differential action at peripheral and central α(2) receptors. A strategy for improving the therapeutic window of α(2) antagonists is put forward.
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Affiliation(s)
- Bernard Vacher
- Medicinal Chemistry 1 Division, Pierre Fabre Research Center,17 Avenue Jean Moulin, 81106 Castres Cedex, France.
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50
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Lu R, Chen Y, Cottingham C, Peng N, Jiao K, Limbird LE, Wyss JM, Wang Q. Enhanced hypotensive, bradycardic, and hypnotic responses to alpha2-adrenergic agonists in spinophilin-null mice are accompanied by increased G protein coupling to the alpha2A-adrenergic receptor. Mol Pharmacol 2010; 78:279-86. [PMID: 20430865 DOI: 10.1124/mol.110.065300] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We previously identified spinophilin as a regulator of alpha(2) adrenergic receptor (alpha(2)AR) trafficking and signaling in vitro and in vivo (Science 304:1940-1944, 2004). To assess the generalized role of spinophilin in regulating alpha(2)AR functions in vivo, the present study examined the impact of eliminating spinophilin on alpha(2)AR-evoked cardiovascular and hypnotic responses, previously demonstrated to be mediated by the alpha(2A)AR subtype, after systemic administration of the alpha(2)-agonists 5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine (UK14,304) and clonidine in spinophilin-null mice. Mice lacking spinophilin expression display dramatically enhanced and prolonged hypotensive, bradycardic, and sedative-hypnotic responses to alpha(2)AR stimulation. Whereas these changes in sensitivity to alpha(2)AR agonists occur independent of any changes in alpha(2A)AR density or intrinsic affinity for agonist in the brains of spinophilin-null mice compared with wild-type control mice, the coupling of the alpha(2A)AR to cognate G proteins is enhanced in spinophilin-null mice. Thus, brain preparations from spinophilin-null mice demonstrate enhanced guanine nucleotide regulation of UK14,304 binding and evidence of a larger fraction of alpha(2A)AR in the guanine-nucleotide-sensitive higher affinity state compared with those from wild-type mice. These findings suggest that eliminating spinophilin expression in native tissues leads to an enhanced receptor/G protein coupling efficiency that contributes to sensitization of receptor mediated responses in vivo.
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Affiliation(s)
- R Lu
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama, USA
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