1
|
Baker JG, Summers RJ. Adrenoceptors: Receptors, Ligands and Their Clinical Uses, Molecular Pharmacology and Assays. Handb Exp Pharmacol 2024; 285:55-145. [PMID: 38926158 DOI: 10.1007/164_2024_713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2024]
Abstract
The nine G protein-coupled adrenoceptor subtypes are where the endogenous catecholamines adrenaline and noradrenaline interact with cells. Since they are important therapeutic targets, over a century of effort has been put into developing drugs that modify their activity. This chapter provides an outline of how we have arrived at current knowledge of the receptors, their physiological roles and the methods used to develop ligands. Initial studies in vivo and in vitro with isolated organs and tissues progressed to cell-based techniques and the use of cloned adrenoceptor subtypes together with high-throughput assays that allow close examination of receptors and their signalling pathways. The crystal structures of many of the adrenoceptor subtypes have now been determined opening up new possibilities for drug development.
Collapse
Affiliation(s)
- Jillian G Baker
- Cell Signalling, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, UK.
- Department of Respiratory Medicine, Nottingham University Hospitals NHS Trust, Nottingham, UK.
| | - Roger J Summers
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia.
| |
Collapse
|
2
|
Wei F, Zhang X, Cui P, Gou X, Wang S. Cell-based 3D bionic screening by mimicking the drug-receptor interaction environment in vivo. J Mater Chem B 2021; 9:683-693. [PMID: 33367374 DOI: 10.1039/d0tb02661a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Most small-molecule drugs influence cell behavior through their interaction with one or more cellular proteins. The efficacy is unanticipated in the later stages of drug development if small-molecule drugs are discovered in the absence of a biological context. Bionic screening is an in vivo drug-receptor interaction platform that can identify small molecules with recognized activity, improving the likelihood of drug efficacy in the clinic. Here, we report the design of an innovative cell-based bionic screening system using 3D microcarrier cultures to simulate in vivo conditions and facilitate small-molecule drug discovery. Through its combination with HPLC/MS, the method can comprehensively identify small-molecule lead compounds in arbitrarily complex systems in an unbiased manner. In particular, cell-covered microcarriers provide a high-density of cells for affinity performance assessments in the absence of appreciable cell damage and maintain immunogenicity, the 3D structure of which is similar to tissue morphology in vivo, thereby mimicking in vivo drug-receptor interactions. The method is scalable, easy to handle, and requires minimal optimization across a range of different cell lines to realize high-throughput drug screening for the corresponding diseases. This provides a valuable tool for lead compound discovery in more physiologically relevant systems and may address the lack of clinically available drugs.
Collapse
Affiliation(s)
- Fen Wei
- Health Science Center, School of Pharmacy, Xi'an Jiaotong University, 76# Yanta West Road, Xi'an, 710061, China.
| | | | | | | | | |
Collapse
|
3
|
Yoshioka Y, Negoro R, Kadoi H, Motegi T, Shibagaki F, Yamamuro A, Ishimaru Y, Maeda S. Noradrenaline protects neurons against H 2 O 2 -induced death by increasing the supply of glutathione from astrocytes via β 3 -adrenoceptor stimulation. J Neurosci Res 2020; 99:621-637. [PMID: 32954502 DOI: 10.1002/jnr.24733] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 08/29/2020] [Accepted: 09/01/2020] [Indexed: 11/06/2022]
Abstract
Oxidative stress has been implicated in a variety of neurodegenerative disorders, such as Alzheimer's and Parkinson's disease. Astrocytes play a significant role in maintaining survival of neurons by supplying antioxidants such as glutathione (GSH) to neurons. Recently, we found that noradrenaline increased the intracellular GSH concentration in astrocytes via β3 -adrenoceptor stimulation. These observations suggest that noradrenaline protects neurons from oxidative stress-induced death by increasing the supply of GSH from astrocytes to neurons via the stimulation of β3 -adrenoceptor in astrocytes. In the present study, we examined the protective effect of noradrenaline against H2 O2 -induced neurotoxicity using two different mixed cultures: the mixed culture of human astrocytoma U-251 MG cells and human neuroblastoma SH-SY5Y cells, and the mouse primary cerebrum mixed culture of neurons and astrocytes. H2 O2 -induced neuronal cell death was significantly attenuated by pretreatment with noradrenaline in both mixed cultures but not in single culture of SH-SY5Y cells or in mouse cerebrum neuron-rich culture. The neuroprotective effect of noradrenaline was inhibited by SR59230A, a selective β3 -adrenoceptor antagonist, and CL316243, a selective β3 -adrenoceptor agonist, mimicked the neuroprotective effect of noradrenaline. DL-buthionine-[S,R]-sulfoximine, a GSH synthesis inhibitor, negated the neuroprotective effect of noradrenaline in both mixed cultures. MK571, which inhibits the export of GSH from astrocytes mediated by multidrug resistance-associated protein 1, also prevented the neuroprotective effect of noradrenaline. These results suggest that noradrenaline protects neurons against H2 O2 -induced death by increasing the supply of GSH from astrocytes via β3 -adrenoceptor stimulation.
Collapse
Affiliation(s)
- Yasuhiro Yoshioka
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| | - Ryosuke Negoro
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| | - Hisatsugu Kadoi
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| | - Toshiki Motegi
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| | - Fumiya Shibagaki
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| | - Akiko Yamamuro
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| | - Yuki Ishimaru
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| | - Sadaaki Maeda
- Laboratory of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, Hirakata, Japan
| |
Collapse
|
4
|
Bofill A, Jalencas X, Oprea TI, Mestres J. The human endogenous metabolome as a pharmacology baseline for drug discovery. Drug Discov Today 2019; 24:1806-1820. [PMID: 31226432 DOI: 10.1016/j.drudis.2019.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/17/2019] [Accepted: 06/12/2019] [Indexed: 01/01/2023]
Abstract
We have limited understanding of the variation in in vitro affinities of drugs for their targets. An analysis of a highly curated set of 815 interactions between 566 drugs and 129 primary targets reveals that 71% of drug-target affinities have values above that of the corresponding endogenous ligand, 96% of them fitting within a range of two orders of magnitude. Our findings suggest that the evolutionary optimised affinity of endogenous ligands for their native proteins can serve as a baseline for the primary pharmacology of drugs. We show that the degree of off-target selectivity and safety risks of drugs derived from their secondary pharmacology depend very much on that baseline. Thus, we propose a new approach for estimating safety margins.
Collapse
Affiliation(s)
- Andreu Bofill
- Research Group on Systems Pharmacology, Research Program on Biomedical Informatics (GRIB), IMIM Hospital del Mar Medical Research Institute and University Pompeu Fabra, 08003 Barcelona, Catalonia, Spain
| | - Xavier Jalencas
- Research Group on Systems Pharmacology, Research Program on Biomedical Informatics (GRIB), IMIM Hospital del Mar Medical Research Institute and University Pompeu Fabra, 08003 Barcelona, Catalonia, Spain
| | - Tudor I Oprea
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA; UNM Comprehensive Cancer Center, Albuquerque, NM, USA; Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden; Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jordi Mestres
- Research Group on Systems Pharmacology, Research Program on Biomedical Informatics (GRIB), IMIM Hospital del Mar Medical Research Institute and University Pompeu Fabra, 08003 Barcelona, Catalonia, Spain.
| |
Collapse
|
5
|
Mitchell A, Hall RW, Erickson SW, Yates C, Lowery S, Hendrickson H. Systemic Absorption of Cyclopentolate and Adverse Events After Retinopathy of Prematurity Exams. Curr Eye Res 2016; 41:1601-1607. [PMID: 27159349 DOI: 10.3109/02713683.2015.1136419] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
PURPOSE Preterm infants undergoing Retinopathy of Prematurity Eye Exams (ROPEE) may experience adverse events, possibly from systemic absorption of cyclopentolate. The purpose of this study was to analyze the association between adverse events and drug levels found in neonates undergoing ROPEE. MATERIALS AND METHODS 25 infants were randomized into two groups during routine ROP screening: 5 infants for blood collection before mydriatic drops and 20 for blood collection 1 h after eye drops. Blood was collected onto dried blood spot cards, extracted, and analyzed for cyclopentolate and phenylephrine using liquid chromatography and mass spectrometry. Relationships between drug levels and adverse events were assessed. RESULTS Cyclopentolate (range 6-53 ng/ml) was observed in 15 of 18 infants, while phenylephrine was not detected. Levels of cyclopentolate were significantly higher in infants who were on oxygen (p = 0.01). There was a significant association between cyclopentolate levels and gastric residuals in tube-fed infants not receiving oxygen (p = 0.01). CONCLUSIONS Cyclopentolate levels varied among preterm infants after ROPEE. Cyclopentolate was positively associated with increased gastric residuals. Underlying medical conditions requiring oxygen administration may affect absorption and metabolism of cyclopentolate. There is a need to predict infants at risk for high blood levels of cyclopentolate in order to prevent or treat adverse events after ROPEE.
Collapse
Affiliation(s)
- Anita Mitchell
- a Department of Nursing Science , College of Nursing, University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Richard W Hall
- b Department of Pediatrics , College of Medicine, University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Stephen W Erickson
- c Department of Biostatistics , University of Arkansas for Medical Sciences , Little Rock , AR , USA
| | - Charlotte Yates
- d Department of Physical Therapy , University of Central Arkansas , Conway , AR , USA
| | | | - Howard Hendrickson
- e Department of Pharmaceutical Sciences , College of Pharmacy, University of Arkansas for Medical Sciences , Little Rock , AR , USA
| |
Collapse
|
6
|
Alexandre EC, Kiguti LR, Calmasini FB, Silva FH, da Silva KP, Ferreira R, Ribeiro CA, Mónica FZ, Pupo AS, Antunes E. Mirabegron relaxes urethral smooth muscle by a dual mechanism involving β3 -adrenoceptor activation and α1 -adrenoceptor blockade. Br J Pharmacol 2016; 173:415-28. [PMID: 26493129 DOI: 10.1111/bph.13367] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 09/16/2015] [Accepted: 10/19/2015] [Indexed: 01/14/2023] Open
Abstract
LINKED ARTICLE This article is commented on by Michel, M. C., pp. 429-430 of this issue. To view this commentary visit http://dx.doi.org/10.1111/bph.13379. BACKGROUND AND PURPOSE Mirabegron is the first β3 -adrenoceptor agonist approved for treatment of overactive bladder syndrome. This study aimed to investigate the effects of β3 -adrenoceptor agonist mirabegron in mouse urethra. The possibility that mirabegron also exerts α1 -adrenoceptor antagonism was also tested in rat smooth muscle preparations presenting α1A - (vas deferens and prostate), α1D - (aorta) and α1B -adrenoceptors (spleen). EXPERIMENTAL APPROACH Functional assays were carried out in mouse and rat isolated tissues. Competition assays for the specific binding of [(3) H]prazosin to membrane preparations of HEK-293 cells expressing each of the human α1 -adrenoceptors, as well as β-adrenoceptor mRNA expression and cyclic AMP measurements in mouse urethra, were performed. KEY RESULTS Mirabegron produced concentration-dependent urethral relaxations that were shifted to the right by the selective β3 -adrenoceptor antagonist L-748,337 but unaffected by β1 - and β2 -adrenoceptor antagonists (atenolol and ICI-118,551 respectively). Mirabegron-induced relaxations were enhanced by the PDE4 inhibitor rolipram, and the agonist stimulated cAMP synthesis. Mirabegron also produced rightward shifts in urethral contractions induced by the α1 -adrenoceptor agonist phenylephrine. Schild regression analysis revealed that mirabegron behaves as a competitive antagonist of α1 -adrenoceptors in urethra, vas deferens and prostate (α1A -adrenoceptor, pA2 ≅ 5.6) and aorta (α1D -adrenoceptor, pA2 ≅ 5.4) but not in spleen (α1B -adrenoceptor). The affinities estimated for mirabegron in functional assays were consistent with those estimated in radioligand binding with human recombinant α1A - and α1D -adrenoceptors (pKi ≅ 6.0). CONCLUSION AND IMPLICATIONS The effects of mirabegron in urethral smooth muscle are the result of β3 -adrenoceptor agonism together with α1A and α1D -adrenoceptor antagonism.
Collapse
Affiliation(s)
- E C Alexandre
- Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - L R Kiguti
- Department of Pharmacology, Institute of Biosciences, University of São Paulo State (UNESP), Botucatu, São Paulo, Brazil
| | - F B Calmasini
- Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - F H Silva
- Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - K P da Silva
- Department of Pharmacology, Institute of Biosciences, University of São Paulo State (UNESP), Botucatu, São Paulo, Brazil
| | - R Ferreira
- Hematology and Hemotherapy Center, Faculty of Medical Sciences, University of Campinas (UNICAMP), Campinas, Brazil
| | - C A Ribeiro
- Department of Pharmacology, Institute of Biosciences, University of São Paulo State (UNESP), Botucatu, São Paulo, Brazil
| | - F Z Mónica
- Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| | - A S Pupo
- Department of Pharmacology, Institute of Biosciences, University of São Paulo State (UNESP), Botucatu, São Paulo, Brazil
| | - E Antunes
- Department of Pharmacology, University of Campinas (UNICAMP), Campinas, Brazil
| |
Collapse
|
7
|
Yoshioka Y, Kadoi H, Yamamuro A, Ishimaru Y, Maeda S. Noradrenaline increases intracellular glutathione in human astrocytoma U-251 MG cells by inducing glutamate-cysteine ligase protein via β3-adrenoceptor stimulation. Eur J Pharmacol 2015; 772:51-61. [PMID: 26724392 DOI: 10.1016/j.ejphar.2015.12.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/16/2015] [Accepted: 12/22/2015] [Indexed: 11/16/2022]
Abstract
Glutathione (GSH) plays a critical role in protecting cells from oxidative damage. Since neurons rely on the supply of GSH from astrocytes to maintain optimal intracellular GSH concentrations, the GSH concentration of astrocytes is important for the survival of neighboring neurons against oxidative stress. The neurotransmitter noradrenaline is known to modulate the functions of astrocytes and has been suggested to have neuroprotective properties in neurodegenerative diseases. To elucidate the mechanisms underlying the neuroprotective properties of noradrenaline, in this study, we investigated the effect of noradrenaline on the concentrations of intracellular GSH in human U-251 malignant glioma (MG; astrocytoma) cells. Treatment of the cells with noradrenaline for 24h concentration-dependently increased their intracellular GSH concentration. This increase was inhibited by a non-selective β-adrenoceptor antagonist propranolol and by a selective β3-adrenoceptor antagonist SR59230A, but not by a non-selective α-adrenoceptor antagonist phenoxybenzamine, or by a selective β1-adrenoceptor antagonist atenolol or by a selective β2-adrenoceptor antagonist butoxamine. In addition, the selective β3-adrenoceptor agonist CL316243 increased the intracellular GSH in U-251 MG cells. Treatment of the cells with noradrenaline (10μM) for 24h increased the protein level of the catalytic subunit of glutamate-cysteine ligase (GCLc), the rate-limiting enzyme of GSH synthesis; and this increase was inhibited by SR59230A. These results thus suggest that noradrenaline increased the GSH concentration in astrocytes by inducing GCLc protein in them via β3-adrenoceptor stimulation.
Collapse
Affiliation(s)
- Yasuhiro Yoshioka
- Department of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan.
| | - Hisatsugu Kadoi
- Department of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan.
| | - Akiko Yamamuro
- Department of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan.
| | - Yuki Ishimaru
- Department of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan.
| | - Sadaaki Maeda
- Department of Pharmacotherapeutics, Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan.
| |
Collapse
|
8
|
Michel MC, Seifert R. Selectivity of pharmacological tools: implications for use in cell physiology. A review in the theme: Cell signaling: proteins, pathways and mechanisms. Am J Physiol Cell Physiol 2015; 308:C505-20. [PMID: 25631871 DOI: 10.1152/ajpcell.00389.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 01/24/2015] [Indexed: 01/08/2023]
Abstract
Pharmacological inhibitors are frequently used to identify the receptors, receptor subtypes, and associated signaling pathways involved in physiological cell responses. Based on the effects of such inhibitors conclusions are drawn about the involvement of their assumed target or lack thereof. While such inhibitors can be useful tools for a better physiological understanding, their uncritical use can lead to incorrect conclusions. This article reviews the concept of inhibitor selectivity and its implication for cell physiology. Specifically, we discuss the implications of using inhibitor vs. activator approaches, issues of direct vs. indirect pathway modulation, implications of inverse agonism and biased signaling, and those of orthosteric vs. allosteric, competitive vs. noncompetitive, and reversible vs. irreversible inhibition. Additional problems can result from inconsistent estimates of inhibitor potency and differences in potency between cell-free systems and intact cells. These concepts are illustrated by several examples of inhibitors displaying affinity for related but distinct targets or even unrelated targets. Of note, many of the issues being addressed are also applicable to genetic inhibition strategies. The main practical conclusion following from these concepts is that investigators should be critical in the choice of inhibitor, its concentrations, and its mode of application. When this advice is adhered to, small-molecule pharmacological inhibitors can be important experimental tools in the hand of physiologists.
Collapse
Affiliation(s)
- Martin C Michel
- Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany; and
| | - Roland Seifert
- Department of Pharmacology, Hannover Medical School, Hannover, Germany
| |
Collapse
|
9
|
Nishimune A, Yoshiki H, Uwada J, Anisuzzaman ASM, Umada H, Muramatsu I. Phenotype pharmacology of lower urinary tract α(1)-adrenoceptors. Br J Pharmacol 2012; 165:1226-34. [PMID: 21745191 PMCID: PMC3372711 DOI: 10.1111/j.1476-5381.2011.01591.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 06/20/2011] [Accepted: 06/28/2011] [Indexed: 12/01/2022] Open
Abstract
α(1)-Adrenoceptors are involved in numerous physiological functions, including micturition. However, the pharmacological profile of the α(1)-adrenoceptor subtypes remains controversial. Here, we review the literature regarding α(1)-adrenoceptors in the lower urinary tract from the standpoint of α(1L) phenotype pharmacology. Among three α(1)-adrenoceptor subtypes (α(1A), α(1B) and α(1D)), α(1a)-adrenoceptor mRNA is the most abundantly transcribed in the prostate, urethra and bladder neck of many species, including humans. In prostate homogenates or membrane preparations, α(1A)-adrenoceptors with high affinity for prazosin have been detected as radioligand binding sites. Functional α(1)-adrenoceptors in the prostate, urethra and bladder neck have low affinity for prazosin, suggesting the presence of an atypical α(1)-adrenoceptor phenotype (designated as α(1L)). The α(1L)-adrenoceptor occurs as a distinct binding entity from the α(1A)-adrenoceptor in intact segments of variety of tissues including prostate. Both the α(1L)- and α(1A)-adrenoceptors are specifically absent from Adra1A (α(1a)) gene-knockout mice. Transfection of α(1a)-adrenoceptor cDNA predominantly expresses α(1A)-phenotype in several cultured cell lines. However, in CHO cells, such transfection expresses α(1L)- and α(1A)-phenotypes. Under intact cell conditions, the α(1L)-phenotype is predominant when co-expressed with the receptor interacting protein, CRELD1α. In summary, recent pharmacological studies reveal that two distinct α(1)-adrenoceptor phenotypes (α(1A) and α(1L)) originate from a single Adra1A (α(1a)-adrenoceptor) gene, but adrenergic contractions in the lower urinary tract are predominantly mediated via the α(1L)-adrenoceptor. From the standpoint of phenotype pharmacology, it is likely that phenotype-based subtypes such as the α(1L)-adrenoceptor will become new targets for drug development and pharmacotherapy.
Collapse
Affiliation(s)
- A Nishimune
- Division of Pharmacology, Department of Biochemistry and Bioinformative Sciences, Organization for Life Science Advancement Programs, and Child Development Research Center, School of Medicine, University of Fukui, Eiheiji, Fukui, Japan
| | | | | | | | | | | |
Collapse
|
10
|
Adrenergic control of cardiac gap junction function and expression. Naunyn Schmiedebergs Arch Pharmacol 2011; 383:331-46. [DOI: 10.1007/s00210-011-0603-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 01/17/2011] [Indexed: 10/18/2022]
|
11
|
Nishimune A, Suzuki F, Yoshiki H, Morishima S, Muramatsu I. Identification of Cysteine-Rich Epidermal Growth Factor–Like Domain 1α (CRELD1α) as a Novel α1A-Adrenoceptor–Down-Regulating Protein and Establishment of an α1L-Adrenoceptor–Expressing Cell Line. J Pharmacol Sci 2010; 113:169-81. [DOI: 10.1254/jphs.10093fp] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
|
12
|
Identification of the alpha1L-adrenoceptor in rat cerebral cortex and possible relationship between alpha1L- and alpha1A-adrenoceptors. Br J Pharmacol 2008; 153:1485-94. [PMID: 18223667 DOI: 10.1038/sj.bjp.0707679] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND AND PURPOSE In addition to alpha1A, alpha1B and alpha1D-adrenoceptors (ARs), putative alpha1L-ARs with a low affinity for prazosin have been proposed. The purpose of the present study was to identify the alpha1A-AR and clarify its pharmacological profile using a radioligand binding assay. EXPERIMENTAL APPROACH Binding experiments with [3H]-silodosin and [3H]-prazosin were performed in intact tissue segments and crude membrane preparations of rat cerebral cortex. Intact tissue binding assays were also conducted in rat tail artery. KEY RESULTS [3H]-silodosin at subnanomolar concentrations specifically bound to intact tissue segments and membrane preparations of rat cerebral cortex at the same density (approximately 150 fmol mg(-1) total tissue protein). The binding sites in intact segments consisted of alpha1A and alpha1L-ARs that had different affinities for prazosin, while the binding sites in membranes showed an alpha1A-AR-like profile having single high affinity for prazosin. [3H]-prazosin also bound at subnanomolar concentrations to alpha1A and alpha1B-ARs but not alpha1L-ARs in cerebral cortex; the binding densities being approximately 200 and 290 fmol mg(-1) protein in the segments and the membranes, respectively. In the segments of tail artery, [3H]-silodosin only recognized alpha1A-ARs, whereas [3H]-prazosin bound to alpha1A and alpha1B-ARs. CONCLUSIONS AND IMPLICATIONS The present study clearly reveals the presence of alpha1L-ARs as a pharmacologically distinct entity from alpha1A and alpha1B-ARs in intact tissue segments of rat cerebral cortex but not tail artery. However, the alpha1L-ARs disappeared after tissue homogenization, suggesting their decomposition and/or their pharmacological profile changes to that of alpha1A-ARs.
Collapse
|
13
|
Alpha-1-adrenoceptor subtype selective regulation of connexin 43 expression in rat cardiomyocytes. Naunyn Schmiedebergs Arch Pharmacol 2008; 377:77-85. [DOI: 10.1007/s00210-007-0244-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Accepted: 11/18/2007] [Indexed: 10/22/2022]
|
14
|
Suzuki F, Morishima S, Tanaka T, Muramatsu I. Snapin, a new regulator of receptor signaling, augments alpha1A-adrenoceptor-operated calcium influx through TRPC6. J Biol Chem 2007; 282:29563-73. [PMID: 17684020 DOI: 10.1074/jbc.m702063200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Activation of G(q)-protein-coupled receptors, including the alpha(1A)-adrenoceptor (alpha(1A)-AR), causes a sustained Ca(2+) influx via receptor-operated Ca(2+) (ROC) channels, following the transient release of intracellular Ca(2+). Transient receptor potential canonical (TRPC) channel is one of the candidate proteins constituting the ROC channels, but the precise mechanism linking receptor activation to increased influx of Ca(2+) via TRPCs is not yet fully understood. We identified Snapin as a protein interacting with the C terminus of the alpha(1A)-AR. In receptor-expressing PC12 cells, co-transfection of Snapin augmented alpha(1A)-AR-stimulated sustained increases in intracellular Ca(2+) ([Ca(2+)](i)) via ROC channels. By altering the Snapin binding C-terminal domain of the alpha(1A)-AR or by reducing cellular Snapin with short interfering RNA, the sustained increase in [Ca(2+)](i) in Snapin-alpha(1A)-AR co-expressing PC12 cells was attenuated. Snapin co-immunoprecipitated with TRPC6 and alpha(1A)-AR, and these interactions were augmented upon alpha(1A)-AR activation, increasing the recruitment of TRPC6 to the cell surface. Our data suggest a new receptor-operated signaling mechanism where Snapin links the alpha(1A)-AR to TRPC6, augmenting Ca(2+) influx via ROC channels.
Collapse
Affiliation(s)
- Fumiko Suzuki
- Division of Pharmacology, Department of Biochemistry and Bioinformative Sciences, School of Medicine, University of Fukui, 23-3 Matsuoka-Shimoaizuki, Eiheiji, Fukui 910-1193, Japan
| | | | | | | |
Collapse
|
15
|
Berger A, Lang R, Moritz K, Santic R, Hermann A, Sperl W, Kofler B. Galanin receptor subtype GalR2 mediates apoptosis in SH-SY5Y neuroblastoma cells. Endocrinology 2004; 145:500-7. [PMID: 14592962 DOI: 10.1210/en.2003-0649] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recently we have shown that galanin binding significantly correlates with survival in neuroblastoma patients, indicating a possible modulatory role of galanin receptors in neuroblastic tumor biology. However, the molecular mechanisms beyond this correlation have not been elucidated. Here, the cellular effects on activation of specific galanin receptor subtypes in human SH-SY5Y neuroblastoma cells were analyzed using a tetracycline-controlled expression system. Pharmacological studies confirmed the inducible expression of high affinity binding sites for galanin in SH-SY5Y cells transfected with the galanin receptors GalR1 (SY5Y/GalR1) and GalR2 (SY5Y/GalR2). Microphysiometry revealed that both receptor subtypes were able to mediate an intracellular signal upon galanin application. Interestingly, induction of receptor expression and treatment with 100 nm galanin resulted in a dramatic decrease in cell viability in SY5Y/GalR2 cells (93 +/- 3%) compared with a less pronounced effect in SY5Y/GalR1 cells (19 +/- 10%). The antiproliferative potency of galanin was 100-fold higher in SY5Y/GalR2 (50% effective concentration, 1.1 nm) than in SY5Y/GalR1 cells (50% effective concentration, 190 nm). Furthermore, activation of receptor expression and exposure to galanin resulted in apparent morphological changes indicative of apoptosis in SY5Y/GalR2 cells only. Induction of cell death by the apoptotic process was confirmed by poly-(ADP-ribose)-polymerase cleavage, caspase-3 activation, and the typical laddering of DNA. This study indicates that a high level of GalR2 expression is able to inhibit cell proliferation and induce apoptosis in neuroblastoma cells and therefore identifies GalR2 as a possible target for pharmacological intervention in neuroblastoma.
Collapse
MESH Headings
- Apoptosis/drug effects
- Apoptosis/physiology
- Caspase 3
- Caspases/metabolism
- Cell Division/drug effects
- Cell Division/physiology
- Cell Survival/drug effects
- DNA Fragmentation/drug effects
- Galanin/analysis
- Galanin/metabolism
- Galanin/pharmacology
- Gene Expression/drug effects
- Humans
- Hydrogen-Ion Concentration
- Kinetics
- Neuroblastoma/chemistry
- Neuroblastoma/metabolism
- Neuroblastoma/pathology
- Receptor, Galanin, Type 1/genetics
- Receptor, Galanin, Type 1/physiology
- Receptor, Galanin, Type 2/analysis
- Receptor, Galanin, Type 2/genetics
- Receptor, Galanin, Type 2/physiology
- Tetracycline/pharmacology
- Transfection
- Tumor Cells, Cultured
Collapse
Affiliation(s)
- Alexandra Berger
- Department of Pediatrics, General Hospital Salzburg, Muellner Hauptstrasse 48, A-5020 Salzburg, Austria
| | | | | | | | | | | | | |
Collapse
|
16
|
Israilova M, Tanaka T, Suzuki F, Morishima S, Muramatsu I. Pharmacological Characterization and Cross Talk of α1A- and α1B-Adrenoceptors Coexpressed in Human Embryonic Kidney 293 Cells. J Pharmacol Exp Ther 2004; 309:259-66. [PMID: 14722320 DOI: 10.1124/jpet.103.061796] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We established three human embryonic kidney (HEK) 293 cell lines stably expressing alpha(1)-adrenoceptor (AR) subtypes, one (alpha(1A), (1B)-AR) coexpressing both receptors and the other two (alpha(1A)-AR and alpha(1B)-AR) expressing each receptor in isolation. In the alpha(1A), (1B)-AR cells, both receptors were clearly distinguished by the alpha(1A)-selective ligands (-)-1(3-hydroxypropyl)-5-((2R)-2-([2-(2,2,2-trifluoroethyl]oxy]phenyl)oxy)ethyl]amino)propyl)-2,3-dihydro-1H-indole-7-carboxamide (KMD-3213) and methoxamine, but not by the subtype-nonselective ligands prazosin and phenylephrine. In all three cell lines, phenylephrine caused a concentration-dependent increase in inositol phosphates and an increase in extracellular signal-regulated kinase 1/2 (ERK1/2) activation. However, there was a 2-fold or greater maximal response to phenylephrine and a somewhat higher agonist potency in ERK1/2 activation in the alpha(1A,1B)-AR cells, compared with the responses of cells expressing either receptor individually (alpha(1A)-AR or alpha(1B)-AR). Furthermore, the antagonistic affinities of prazosin (pK(b) of 10.1) and KMD-3213 (9.4) for inhibiting the phenylephrine response were intermediate between the values for inhibition in alpha(1A)-AR cells (prazosin, 9.3; KMD-3213, 10.5) and alpha(1B)-AR cells (prazosin, 11.0; KMD-3213, 8.1). The inhibitor pK(b) values in alpha(1A), (1B)-AR also differed from their ligand binding affinities measured in alpha(1A)-AR and alpha(1B)-AR cells. In contrast, the alpha(1A)-selective agonist methoxamine, which did not activate alpha(1B)-AR cells, stimulated either alpha(1A,) (1B)-AR or alpha(1A)-AR cells with a comparable potency and maximum effectiveness. Our data indicate that when coexpressed in the same cell, the activation of common pathways by individual AR receptor subtypes by a nonselective agonist can exhibit enhanced responsiveness and a distinct antagonist affinity compared with the parameters for the same receptors, when expressed alone in the same cell background.
Collapse
Affiliation(s)
- Malika Israilova
- Division of Pharmacology, Department of Biochemistry and Bioinformative Sciences, School of Medicine, University of Fukui, Matsuoka, Fukui 910-1193, Japan
| | | | | | | | | |
Collapse
|
17
|
Hiraoka Y, Taniguchi T, Tanaka T, Okada K, Kanamaru H, Muramatsu I. Pharmacological characterization of unique prazosin-binding sites in human kidney. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2003; 368:49-56. [PMID: 12827214 DOI: 10.1007/s00210-003-0764-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2002] [Accepted: 04/18/2003] [Indexed: 10/26/2022]
Abstract
In human kidney, we found unique prazosin-binding sites that were insensitive to phentolamine and were thus unlikely to be alpha(1)-adrenoceptors. As the binding of [(3)H]prazosin to phentolamine-insensitive sites was prevented by 100 microM guanabenz, the insensitive sites were evaluated by subtracting [(3)H]prazosin binding in the presence of 100 microM guanabenz from that in the presence of 10 microM phentolamine. [(3)H]Prazosin bound to the phentolamine-insensitive sites monophasically with a high affinity (pK(d); 9.1+/-0.08, n=8), and the B(max) value (814+/-204 fmol mg(-1) protein, n=8) was more than ten times that of the phentolamine-sensitive alpha(1)-adrenoceptor (pK(d)=9.9+/-0.13, B(max)=66+/-23 fmol mg(-1) protein, n=7). The phentolamine-insensitive sites in human kidney were highly sensitive to other quinazoline derivatives such as terazosin and doxazosin. However, other alpha(1)-adrenoceptor antagonists (tamsulosin, WB4101 and corynanthine) did not inhibit the binding at a range of concentrations that generally exhibit alpha(1)-adrenoceptor antagonism, and noradrenaline, rauwolscine and propranolol were without effect on the [(3)H]prazosin binding. On the other hand, ligands for the renal Na(+)-transporter (amiloride and triamterene) and for imidazoline recognition sites (guanabenz, guanfacine and agmatine) displaced the binding of [(3)H]prazosin to phentolamine-insensitive sites at micromolar concentrations. Photoaffinity labeling with [(125)I]iodoarylazidoprazosin showed phentolamine-insensitive labeling at around 100 kDa, a molecular size larger than that of human alpha(1a)- and alpha(1b)-adrenoceptors expressed in 293 cells (50-60 and 70-80 kDa, respectively) on electrophoresis. In contrast, there was no detectable phentolamine-insensitive binding site but were phentolamine-sensitive alpha(1)-adrenoceptors in human liver (pK(d)=10.0+/-0.06, B(max)=44+/-6 fmol mg(-1) protein, n=3). Phentolamine-insensitive prazosin binding sites were also detected in rabbit kidney (approximately 50% of specific binding sites) but were minor in rat kidney (less than 20%). In conclusion, there are unique prazosin-binding sites in human kidney, the pharmacological profiles of which were distinct from those of known adrenoceptors.
Collapse
Affiliation(s)
- Yasuko Hiraoka
- Department of Pharmacology, School of Medicine, Fukui Medical University, 910-1193 Matsuoka, Fukui, Japan
| | | | | | | | | | | |
Collapse
|
18
|
Okada Y, Taniguchi T, Akagi Y, Muramatsu I. Two-phase response of acid extrusion triggered by purinoceptor in Chinese hamster ovary cells. Eur J Pharmacol 2002; 455:19-25. [PMID: 12433590 DOI: 10.1016/s0014-2999(02)02556-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The functional characteristics of purinoceptors in Chinese hamster ovary (CHO) cells were investigated using a microphysiometer which detects small metabolic changes to living cells in real-time as variations of pH in the extracellular microenvironment. Uridine 5'-triphosphate (UTP) increased the extracellular acidification rate biphasically, namely a transient and a steady response were observed. The transient phase reached a peak (four- to fivefold the basal extracellular acidification rate in amplitude) within 20 s and was followed by the steady phase which was sustained for more than 1 min at an amplitude less than twofold the basal extracellular acidification rate. Both phases showed a concentration-dependent increase in response to UTP. However, there was a significant difference in the pEC(50) value for UTP between the transient (4.8) and steady phases (6.1). Like UTP, ATP increased the extracellular acidification rate, but alpha,beta-methyleneATP (alpha,beta-MeATP), 2-methylthioATP (2-MeSATP), ADP, UDP and adenosine did not. This result suggests that the acid is extruded through a P2Y(2) or P2Y(2)-like purinoceptor. 5-(N-ethyl-N-isopropyl) amiloride (EIPA) and 4-isopropyl-3-methylsulphonylbenzoyl-guanidine methanesulphonate (HOE642) suppressed both phases of the UTP-stimulated extracellular acidification rate response with high affinity (pIC(50): approximately 7.0). This result suggests that the Na(+)/H(+) exchanger 1 (NHE-1) predominantly mediates the UTP-induced acid extrusion response in CHO cells. Elimination of extracellular Ca(2+) or treatment with thapsigargin diminished both phases of the UTP-stimulated extracellular acidification rate. In addition, N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide hydrochloride (W-7) also abrogated the two phases. These results are consistent with the involvement of NHE-1 which is activated via Ca(2+)/calmodulin. Persistent exposure to UTP reduced both extracellular acidification rate phases, causing desensitization of the P2Y purinoceptor. This desensitization did not affect the acid extrusion response mediated by the alpha(1)-adrenoceptor.
Collapse
Affiliation(s)
- Yuichi Okada
- Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193, Japan
| | | | | | | |
Collapse
|
19
|
Takakura K, Taniguchi T, Muramatsu I, Takeuchi K, Fukuda S. Modification of alpha1 -adrenoceptors by peroxynitrite as a possible mechanism of systemic hypotension in sepsis. Crit Care Med 2002; 30:894-9. [PMID: 11940765 DOI: 10.1097/00003246-200204000-00030] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE It is well known that nitric oxide synthase is induced by endotoxin or inflammatory cytokines, and consequently large amounts of nitric oxide cause vascular hyporeactivity to vasoconstrictor agents and myocardial dysfunction, hence hypotension. However, there is considerable controversy as to whether these pathologic cardiovascular features are mediated directly by nitric oxide or also through the formation of secondary reaction products such as peroxynitrite (ONOO-1). Our objective was to investigate inhibitory effects of ONOO-1 on alpha1-adrenoceptors. DESIGN Prospective, controlled, in vitro, laboratory study. SETTING Laboratory of a health sciences university. SUBJECTS Chinese hamster ovary cells that expressed the human recombinant alpha1a-, alpha1b-, or alpha1d-adrenoceptors, rat aorta strips. INTERVENTIONS Binding experiments of [3H]prazosin were done in the Chinese hamster ovary cell membranes pretreated with 100 microM to 3 mM ONOO-1. Displacement experiments with noradrenaline or 3-nitro-l-tyrosine also were conducted. Mobilization of intracellular Ca2+ evoked by 1 nM to 10 microM noradrenaline was monitored in a fluorescence spectrophotometer with dual excitation at 340 nm/380 nm and emission at 500 nm in fura-2/AM-loaded Chinese hamster ovary cells. Contractile force produced by noradrenaline was monitored in rat aorta strips that have alpha1a- and alpha1d-adrenoceptors, pretreated with 1 mM ONOO-1. Either 0.3 N NaOH or the decomposed ONOO-1 was used as the control. MEASUREMENTS AND MAIN RESULTS The specific binding of [3H]prazosin to alpha1a- and alpha1d-adrenoceptor was inhibited by ONOO-1 in a concentration-dependent manner. We found that 3 mM ONOO-1 decreased maximum binding sites by 40% to 50% in alpha1a- and alpha1d-adrenoceptors. Binding affinities for prazosin and noradrenaline were not affected by 1 mM ONOO-1 in all subtypes. We found that 3-nitro-l-tyrosine did not affect the prazosin binding to three adrenoceptor subtypes. Noradrenaline increased intracellular Ca2+ concentration ([Ca2+]i) concentration-dependently, which was inhibited by ONOO-1 in alpha1a- and alpha1d-adrenoceptors. ONOO-1 had no effect on alpha1b-adrenoceptor. Contractile force produced by noradrenaline decreased significantly in aorta strips pretreated with ONOO-1. CONCLUSION ONOO-1 reduces the binding capacity of alpha1a- and alpha1d- but not alpha1b-adrenoceptors without changing the affinities. Treatment with ONOO-1 attenuates noradrenaline-stimulated increase in [Ca2+]i in alpha1a- and alpha1d-adrenoceptors but not in alpha1b-adrenoceptor. ONOO-1 also weakens noradrenaline-induced contractions in rat aorta that has alpha1a- and alpha1d-adrenoceptors. Cardiovascular hyporeactivity to catecholamines in septic shock may be caused in part by the inactivation of alpha-adrenoceptors by ONOO-1.
Collapse
Affiliation(s)
- Ko Takakura
- Department of Anesthesiology and Reanimatology, Fukui Medical University, Matsuoka, Fukui, Japan.
| | | | | | | | | |
Collapse
|
20
|
Taniguchi T, Inagaki R, Suzuki F, Muramatsu I. Rapid acid extrusion response triggered by alpha(1) adrenoceptor in CHO cells. J Physiol 2001; 535:107-13. [PMID: 11507161 PMCID: PMC2278765 DOI: 10.1111/j.1469-7793.2001.00107.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
1. Using a microphysiometer with synchronized valve switching, we investigated real-time acid extrusion from Chinese hamster ovary (CHO) cells in which human alpha(1) adrenoceptor (AR) is stably expressed, in response to noradrenaline (NA). 2. In the cells expressing alpha(1a) AR, the time course of extracellular acidification after stimulation had two phases; in the first phase it transiently reached a rate several times greater than the base rate with a peak at around 10 s, and in the second it increased to 2 times the base rate and reached a plateau in 2 min. Both phases showed a concentration-dependent increase of acidification rate in response to NA, but had distinct pEC(50) values; 5.6 for the transient phase and 7.2 for the steady phase. 3. In the cells expressing alpha(1b) AR, the transient phase was not detected but the steady phase was observed. The pEC(50) value was 7.1, although the magnitude of the response was much smaller than that with alpha(1a) AR. 4. Both 5-(N-ethyl-N-isopropyl)amiloride (EIPA) and HOE642 inhibited the acid extrusion response by either AR in a concentration-dependent manner. EIPA and HOE642 had high pIC(50) values (7.4 and 7.3, respectively) for inhibition of the transient phase response via alpha(1a) AR. In the inhibition of the steady phase response via alpha(1a) AR, both drugs revealed the presence of two components in the response; one had high pIC(50) values (8.1 and 8.2 for EIPA and HOE642, respectively) and the other had low pIC(50) values (5.6 and 6.0, respectively). In contrast, the steady phase response via alpha(1b) AR was inhibited by EIPA and HOE642 with low pIC(50) values (5.3 and 5.9, respectively). 5. As Ca2+ was depleted, the alpha(1a) AR-induced transient phase disappeared, while the steady phase was not affected. 6. These results suggest that alpha(1a) AR drives two acid extrusion systems in CHO cells upon stimulation; one elicits the transient response, which is largely mediated by an EIPA/HOE642-sensitive and Ca(2+)-dependent Na(+)-H(+) exchanger (NHE), presumably NHE1, and the other induces the steady acid extrusion that is mediated by NHE1 and another NHE which has low sensitivity to both EIPA and HOE642. alpha(1b) AR drives only the steady phase acid extrusion response, which is mainly mediated by NHEs other than NHE1.
Collapse
Affiliation(s)
- T Taniguchi
- Department of Pharmacology, School of Medicine, Fukui Medical University, 23 Shimoaizuki, Matsuoka, Fukui 910-1193, Japan
| | | | | | | |
Collapse
|
21
|
Yoshio R, Taniguchi T, Itoh H, Muramatsu I. Affinity of serotonin receptor antagonists and agonists to recombinant and native alpha1-adrenoceptor subtypes. JAPANESE JOURNAL OF PHARMACOLOGY 2001; 86:189-95. [PMID: 11459121 DOI: 10.1254/jjp.86.189] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Binding affinities of serotonin (5-HT)-receptor antagonists and agonists at human recombinant alpha1-adrenoceptor subtypes (alpha1a-, alpha1b- and alpha1d-subtypes) were examined and compared with the functional affinities obtained in rat caudal artery (alpha1A-subtype), dog carotid artery (alpha1B-subtype) and rat thoracic aorta (alpha1D-subtype). Most of the 5-HT-receptor antagonists and agonists tested showed relatively high affinity to three alpha1-adrenoceptor subtypes. The highest affinity close to 1 nM was seen for NAN-190 (5-HT1A antagonist) in binding and functional studies. 5-Methylurapidil (5-HT1A agonist) and BMY7378 (5-HT1A agonist) showed, respectively, alpha1a(alpha1A)- or alpha1d(alpha1D)-subtype selectivity in both binding and functional affinities, but spiperone (5-HT2A antagonist) showed alpha1b-selectivity only in binding affinity. Functional affinity of ritanserin (5-HT2A antagonist) to the alpha1B-subtype was approximately 500-fold lower than that of affinity to the alpha1b-subtype. The present results show that many 5-HT-receptor antagonists and agonists have high affinity to alpha1-adrenoceptors, but suggest that there is deviation between their functional affinities and binding affinities for some drugs.
Collapse
Affiliation(s)
- R Yoshio
- Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, Japan
| | | | | | | |
Collapse
|
22
|
Zhu J, Taniguchi T, Takauji R, Suzuki F, Tanaka T, Muramatsu I. Inverse agonism and neutral antagonism at a constitutively active alpha-1a adrenoceptor. Br J Pharmacol 2000; 131:546-52. [PMID: 11015306 PMCID: PMC1572343 DOI: 10.1038/sj.bjp.0703584] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We have studied the antagonist action of prazosin and KMD-3213 in a constitutively active mutant of the human alpha-1a adrenoceptor in which Ala(271) was substituted to Thr and was expressed in CHO cells. Inverse agonism was characterized by up-regulation of receptor density, a decrease in basal GTPgammaS binding, and a reduction in basal inositol-1,4,5-trisphosphate (IP(3)) level. According to the above criteria, prazosin acted as an inverse agonist, whilst KMD-3213 behaved as a neutral antagonist. Compared with the wild-type receptor, mutant receptor exhibited single affinity sites for [(3)H]-prazosin, [(3)H]-KMD and the non-radioactive ligands tested, and displayed significantly higher affinities for several agonists but not for the two antagonists. Administration of KMD-3213 to prazosin-treated CHO cells expressing the mutant receptor reversed the inverse agonism of prazosin resulting in rapid increases in cellular IP(3), in intracellular [Ca(2+)] and in the rate of extracellular acidification. These results indicated that a neutral antagonist can reverse the action of an inverse agonist at the receptor site. The distinct properties of inverse agonist and neutral antagonist in affecting receptor function may be important for the clinical use of such antagonists.
Collapse
Affiliation(s)
- Jun Zhu
- Department of Pharmacology, School of Medicine, Fukui Medical University, 23 Shimoaizuki, Matsuoka, Fukui, 910-1193 Japan
| | - Takanobu Taniguchi
- Department of Pharmacology, School of Medicine, Fukui Medical University, 23 Shimoaizuki, Matsuoka, Fukui, 910-1193 Japan
| | - Rumiko Takauji
- Department of Pharmacology, School of Medicine, Fukui Medical University, 23 Shimoaizuki, Matsuoka, Fukui, 910-1193 Japan
| | - Fumiko Suzuki
- Department of Pharmacology, School of Medicine, Fukui Medical University, 23 Shimoaizuki, Matsuoka, Fukui, 910-1193 Japan
| | - Takashi Tanaka
- Department of Pharmacology, School of Medicine, Fukui Medical University, 23 Shimoaizuki, Matsuoka, Fukui, 910-1193 Japan
| | - Ikunobu Muramatsu
- Department of Pharmacology, School of Medicine, Fukui Medical University, 23 Shimoaizuki, Matsuoka, Fukui, 910-1193 Japan
- Author for correspondence:
| |
Collapse
|
23
|
Suzuki F, Taniguchi T, Takauji R, Murata S, Muramatsu I. Splice isoforms of alpha(1a)-adrenoceptor in rabbit. Br J Pharmacol 2000; 129:1569-76. [PMID: 10780960 PMCID: PMC1572000 DOI: 10.1038/sj.bjp.0703242] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Two splice isoforms of rabbit alpha(1a)-adrenergic receptor (AR), (named alpha(1a)-OCU.2-AR and alpha(1a)-OCU.3-AR) have been isolated from the liver cDNA library in addition to the previously reported isoform (alpha(1a)-OCU.1-AR). Although they have the identical splice position with human alpha(1a)-AR isoforms, the C-terminal sequences are distinct from those of human isoforms. Among these rabbit alpha(1a)-AR isoforms, there are no significant differences in pharmacological properties: high affinity for prazosin, WB4101, KMD-3213 and YM617 and low affinity for BMY7378, using COS-7 cells expressing each isoform by radioligand binding assay. Competitive reverse transcription-polymerase chain reaction (RT - PCR) analysis revealed that mRNA of alpha(1a)-ARs was expressed in liver, thoracic aorta, brain stem and thalamus of rabbit. The splice isoforms exhibited a distinct distribution pattern in rabbit; alpha(1a)-OCU. 1-AR was expressed most abundantly in those tissues. CHO clones, stably expressing each isoforms with receptor density 740 fmol mg(-1) protein in alpha(1a)-OCU.1-AR, 1200 fmol mg(-1) in alpha(1a)-OCU.2-AR and 570 fmol mg(-1) in alpha(1a)-OCU.3-AR, respectively, showed a noradrenaline-induced increase in inositol trisphosphate which was suppressed by prazosin. Noradrenaline elicited a concentration-dependent increase in extracellular acidification rate (EAR) in the CHO clones with pEC(50) values of 6. 19 for alpha(1a)-OCU.1-AR, 6.49 for alpha(1a)-OCU.2-AR and 6.58 for alpha(1a)-OCU.3-AR, respectively. Noradrenaline caused a concentration-dependent increase in intracellular Ca(2+) concentration ([Ca(2+)]i) in the CHO clones with pEC(50) values of 6. 14 for alpha(1a)-OCU.1-AR, 7.25 for alpha(1a)-OCU.2-AR and 7.70 for alpha(1a)-OCU.3-AR, respectively. In conclusion, the present study shows the occurrence of three splice isoforms of rabbit alpha(1a)-AR, which are unique in C-terminal sequence and in tissue distribution. They show similar pharmacological profiles in binding studies but alpha(1a)-OCU.3-AR had the highest potency of noradrenaline in functional studies in spite of the lowest receptor density. These findings suggest that the structure of C-terminus of alpha(1a)-ARs may give the characteristic functional profile.
Collapse
Affiliation(s)
- Fumiko Suzuki
- Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193, Japan
| | - Takanobu Taniguchi
- Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193, Japan
| | - Rumiko Takauji
- Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193, Japan
| | - Satoshi Murata
- Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193, Japan
| | - Ikunobu Muramatsu
- Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193, Japan
- Author for correspondence:
| |
Collapse
|