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da Silva SB, Feitosa SGD, de L Alves SM, Santos RCA, Dos Anjos JV, Araújo AV. A Concise and Useful Guide to Understand How Alpha1 Adrenoceptor Antagonists Work. Mini Rev Med Chem 2022; 22:2383-2405. [PMID: 35507746 DOI: 10.2174/1389557522666220504141949] [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: 02/04/2022] [Revised: 02/23/2022] [Accepted: 03/16/2022] [Indexed: 11/22/2022]
Abstract
Adrenoceptors are the receptors for the catecholamines, adrenaline and noradrenaline. They are divided in α (α1 and α2) and β (β1, β2 and β3). α1-Adrenoceptors are subdivided in α1A, α1B and α1D. Most tissues express mixtures of α1-adrenoceptors subtypes, which appear to coexist in different densities and ratios, and in most cases their responses are probably due to the activation of more than one type. The three subtypes of α1-adrenoceptors are G-protein-coupled receptors (GPCR), specifically coupled to Gq/11. Additionally, the activation of these receptors may activate other signaling pathways or different components of these pathways, which leads to a great variety of possible cellular effects. The first clinically used α1 antagonist was Prazosin, for Systemic Arterial Hypertension (SAH). It was followed by its congeners, Terazosin and Doxazosin. Nowadays, there are many classes of α-adrenergic antagonists with different selectivity profiles. In addition to SAH, the α1-adrenoceptors are used for the treatment of Benign Prostatic Hyperplasia (BPH) and urolithiasis. This antagonism may be part of the mechanism of action of tricyclic antidepressants. Moreover, the activation of these receptors may lead to adverse effects such as orthostatic hypotension, similar to what happens with the antidepressants and with some antipsychotic. Structure-activity relationships can explain, in part, how antagonists work and how selective they can be for each one of the subtypes. However, it is necessary to develop new molecules which antagonize the α1-adrenoceptors or make chemical modifications in these molecules to improve the selectivity, pharmacokinetic profile and/or reduce the adverse effects of known drugs.
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Affiliation(s)
- Sidiane B da Silva
- Laboratório de Nutrição, Atividade Física e Plasticidade Fenotípica - Centro Acadêmico de Vitória - Universidade Federal de Pernambuco. R. Alto do Reservatório, s/n Bela Vista - Vitória de Santo Antão, PE, 50608-680, Brazil
| | - Sidney G D Feitosa
- Departamento de Química Fundamental - Universidade Federal de Pernambuco. Av. Jornalista Aníbal Fernandes, s/n, Cidade Universitária - Recife, PE, 50740-560, Brazil
| | - Silvia M de L Alves
- Laboratório de Nutrição, Atividade Física e Plasticidade Fenotípica - Centro Acadêmico de Vitória - Universidade Federal de Pernambuco. R. Alto do Reservatório, s/n Bela Vista - Vitória de Santo Antão, PE, 50608-680, Brazil
| | - Ruth C A Santos
- Laboratório de Nutrição, Atividade Física e Plasticidade Fenotípica - Centro Acadêmico de Vitória - Universidade Federal de Pernambuco. R. Alto do Reservatório, s/n Bela Vista - Vitória de Santo Antão, PE, 50608-680, Brazil
| | - Janaína V Dos Anjos
- Departamento de Química Fundamental - Universidade Federal de Pernambuco. Av. Jornalista Aníbal Fernandes, s/n, Cidade Universitária - Recife, PE, 50740-560, Brazil
| | - Alice V Araújo
- Núcleo de Saúde Pública, Centro Acadêmico de Vitória - Universidade Federal de Pernambuco R. Alto do Reservatório, s/n Bela Vista - Vitória de Santo Antão, PE, 50608-680, Brazil
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2
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Docherty JR. The pharmacology of α 1-adrenoceptor subtypes. Eur J Pharmacol 2019; 855:305-320. [PMID: 31067439 DOI: 10.1016/j.ejphar.2019.04.047] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 04/17/2019] [Accepted: 04/29/2019] [Indexed: 01/30/2023]
Abstract
This review examines the functions of α1-adrenoceptor subtypes, particularly in terms of contraction of smooth muscle. There are 3 subtypes of α1-adrenoceptor, α1A- α1B- and α1D-adrenoceptors. Evidence is presented that the postulated α1L-adrenoceptor is simply the native α1A-adrenoceptor at which prazosin has low potency. In most isolated tissue studies, smooth muscle contractions to exogenous agonists are mediated particularly by α1A-, with a lesser role for α1D-adrenoceptors, but α1B-adrenoceptors are clearly involved in contractions of some tissues, for example, the spleen. However, nerve-evoked responses are the most crucial physiologically, so that these studies of exogenous agonists may overestimate the importance of α1A-adrenoceptors. The major α1-adrenoceptors involved in blood pressure control by sympathetic nerves are the α1D- and the α1A-adrenoceptors, mediating peripheral vasoconstrictor actions. As noradrenaline has high potency at α1D-adrenceptors, these receptors mediate the fastest response and seem to be targets for neurally released noradrenaline especially to low frequency stimulation, with α1A-adrenoceptors being more important at high frequencies of stimulation. This is true in rodent vas deferens and may be true in vasopressor nerves controlling peripheral resistance and tissue blood flow. The αlA-adrenoceptor may act mainly through Ca2+ entry through L-type channels, whereas the α1D-adrenoceptor may act mainly through T-type channels and exhaustable Ca2+ stores. α1-Adrenoceptors may also act through non-G-protein linked second messenger systems. In many tissues, multiple subtypes of α-adrenoceptor are present, and this may be regarded as the norm rather than exception, although one receptor subtype is usually predominant.
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Affiliation(s)
- James R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, 123 St. Stephen's Green, Dublin 2, Ireland.
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3
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Akinaga J, García-Sáinz JA, S Pupo A. Updates in the function and regulation of α 1 -adrenoceptors. Br J Pharmacol 2019; 176:2343-2357. [PMID: 30740663 DOI: 10.1111/bph.14617] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 12/19/2018] [Accepted: 01/21/2019] [Indexed: 12/16/2022] Open
Abstract
α1 -Adrenoceptors are seven transmembrane domain GPCRs involved in numerous physiological functions controlled by the endogenous catecholamines, noradrenaline and adrenaline, and targeted by drugs useful in therapeutics. Three separate genes, whose products are named α1A -, α1B -, and α1D - adrenoceptors, encode these receptors. Although the existence of multiple α1 -adrenoceptors has been acknowledged for almost 25 years, the specific functions regulated by each subtype are still largely unknown. Despite the limited comprehension, the identification of a single class of subtype-selective ligands for the α1A - adrenoceptors, the so-called α-blockers for prostate dysfunction, has led to major improvement in therapeutics, demonstrating the need for continued efforts in the field. This review article surveys the tissue distribution of the three α1 -adrenoceptor subtypes in the cardiovascular system, genitourinary system, and CNS, highlighting the functions already identified as mediated by the predominant activation of specific subtypes. In addition, this review covers the recent advances in the understanding of the molecular mechanisms involved in the regulation of each of the α1 -adrenoceptor subtypes by phosphorylation and interaction with proteins involved in their desensitization and internalization. LINKED ARTICLES: This article is part of a themed section on Adrenoceptors-New Roles for Old Players. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.14/issuetoc.
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Affiliation(s)
- Juliana Akinaga
- Department of Pharmacology, Instituto de Biociências, UNESP, Botucatu, Brazil
| | - J Adolfo García-Sáinz
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - André S Pupo
- Department of Pharmacology, Instituto de Biociências, UNESP, Botucatu, Brazil
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4
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Fotso Soh J, Strong HR, Daneshtalab N, Tabrizchi R. The effect of inflammation on sympathetic nerve mediated contractions in rat isolated caudal artery. Eur J Pharmacol 2016; 792:54-62. [PMID: 27793651 DOI: 10.1016/j.ejphar.2016.10.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 10/19/2016] [Accepted: 10/21/2016] [Indexed: 10/20/2022]
Abstract
Chronic inflammatory process(es) contributes to changes in vascular function in a variety of diseases. Sympathetic nerve-mediated responses in blood vessels play a pivotal role in regular physiological functions. We tested the hypothesis that sympathetic neuro-effector function will be altered as consequence of inflammatory state. Sympathetic nerve-mediated contractions and alpha adrenergic receptor expressions were evaluated in isolated caudal arteries of rats treated with saline and Complete Freund's adjuvant (CFA). While CFA-treated animals had significantly higher plasma levels of tumor necrosis factor-alpha compared to saline, blood pressure remained unchanged. Immunofluorescence revealed increased expression of ionized calcium adapter binding molecule-1 in the adventitia of blood vessels from CFA-treated animals compared to saline. In isolated arteries, electrical field stimulations between 1.25 and 40Hz resulted in frequency-dependent contractions that wasabolished by tetrodotoxin. Neurogenic contractions from CFA groups were significantly greater than saline. While the presence of alpha1-adrenoceptor antagonist (prazosin) significantly inhibited contractions at lower frequencies of stimulation (1.25-5Hz) in isolated arteries of CFA-treated rats compared to controls, alpha2-adrenoceptor antagonist (rauwolscine) had modest effects. Inhibition of neuronal reuptake by cocaine comparably enhanced field-stimulated responses in vessels of experimental and control animals. Immunofluorescence revealed a difference in expression of alpha1- and alpha2-adrenoceptors in the endothelium of blood vessels of CFA compared to saline controls. Collectively, our observations lend support to enhanced neurogenic contractions in blood vessels of inflamed animals possibly attributing to alterations in responsiveness and/or distribution of post-junctional alpha1-adrenoceptors.
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Affiliation(s)
- Jocelyn Fotso Soh
- Division of BioMedical Sciences, Faculty of Medicine Memorial University, St. John's, NL, Canada
| | - Hilary R Strong
- Division of BioMedical Sciences, Faculty of Medicine Memorial University, St. John's, NL, Canada
| | - Noriko Daneshtalab
- Division of BioMedical Sciences, Faculty of Medicine Memorial University, St. John's, NL, Canada; School of Pharmacy Memorial University, St. John's, NL, Canada.
| | - Reza Tabrizchi
- Division of BioMedical Sciences, Faculty of Medicine Memorial University, St. John's, NL, Canada.
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5
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Akinaga J, Lima V, Kiguti LRDA, Hebeler-Barbosa F, Alcántara-Hernández R, García-Sáinz JA, Pupo AS. Differential phosphorylation, desensitization, and internalization of α1A-adrenoceptors activated by norepinephrine and oxymetazoline. Mol Pharmacol 2013; 83:870-81. [PMID: 23364786 DOI: 10.1124/mol.112.082313] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Loss of response on repetitive drug exposure (i.e., tachyphylaxis) is a particular problem for the vasoconstrictor effects of medications containing oxymetazoline (OXY), an α1-adrenoceptor (AR) agonist of the imidazoline class. One cause of tachyphylaxis is receptor desensitization, usually accompanied by phosphorylation and internalization. It is well established that α1A-ARs are less phosphorylated, desensitized, and internalized on exposure to the phenethylamines norepinephrine (NE), epinephrine, or phenylephrine (PE) than are the α1B and α1D subtypes. However, here we show in human embryonic kidney-293 cells that the low-efficacy agonist OXY induces G protein-coupled receptor kinase 2-dependent α1A-AR phosphorylation, followed by rapid desensitization and internalization (∼40% internalization after 5 minutes of stimulation), whereas phosphorylation of α1A-ARs exposed to NE depends to a large extent on protein kinase C activity and is not followed by desensitization, and the receptors undergo delayed internalization (∼35% after 60 minutes of stimulation). Native α1A-ARs from rat tail artery and vas deferens are also desensitized by OXY, but not by NE or PE, indicating that this property of OXY is not limited to recombinant receptors expressed in cell systems. The results of the present study are clearly indicative of agonist-directed α1A-AR regulation. OXY shows functional selectivity relative to NE and PE at α1A-ARs, leading to significant receptor desensitization and internalization, which is important in view of the therapeutic vasoconstrictor effects of this drug and the varied biologic process regulated by α1A-ARs.
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Affiliation(s)
- Juliana Akinaga
- Department of Pharmacology, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Botucatu, São Paulo, Brazil
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6
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Martínez-Salas SG, Campos-Peralta JM, Pardo JP, Hernández-Muñoz R, Ibarra M, Tanoue A, Tsujimoto G, Villalobos-Molina R. α(1D)-Adrenoceptor regulates the vasopressor action of α(1A)-adrenoceptor in mesenteric vascular bed of α(1D)-adrenoceptor knockout mice. ACTA ACUST UNITED AC 2012; 31:64-71. [PMID: 21951586 DOI: 10.1111/j.1474-8673.2011.00468.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
1 The pressor action of the α(1A)-adrenoceptor (α(1A)-AR) agonist A61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl] methanesulfonamide) and the α(1)-ARs agonist phenylephrine and their blockade by selective α(1)-ARs antagonists in the isolated mesenteric vascular bed of wild-type (WT) mice and α(1D)-AR knockout (KO α(1D)-AR) mice were evaluated. 2 The apparent potency of A61603 to increase the perfusion pressure in the mesenteric vascular bed of WT and KO α(1D)-AR mice is 86 and 138 times the affinity of phenylephrine, respectively. 3 A61603 also enhanced the perfusion pressure by ≈1.7 fold in the mesenteric vascular bed of WT mice compared with KO α(1D)-AR mice. 4 Because of its high affinity, low concentrations of the α(1A)-AR selective antagonist RS100329 (5-methyl-3-[3-[4-[2-(2,2,2,-trifluoroethoxy) phenyl]-1-piperazinyl] propyl]-2,4-(1H)-pyrimidinedione) shifted the agonist concentration-response curves to the right in the mesenteric vascular bed of WT and KO α(1D)-AR mice. 5 The α(1D)-AR selective antagonist BMY7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5] decane-7,9-dione) did not modify the A61603 or the phenylephrine-induced pressor effect. 6 The α(1B/D)-ARs alkylating antagonist chloroethylclonidine (CEC) shifted the agonist concentration-response curves to the right and decreased the maximum phenylephrine-induced vascular contraction in KO α(1D)-AR mice when compared to WT mice; however, CEC only slightly modified the contraction induced by A61603. 7 The results indicate that the isolated mesenteric vascular bed of WT and KO α(1D)-AR mice expresses α(1A)-AR, that the pressor action of α(1A)-AR is up-regulated for α(1D)-AR in WT mice and suggest an important role of α(1B)-AR in the vascular pressure evoked by phenylephrine in KO α(1D)-AR mice.
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Affiliation(s)
- S G Martínez-Salas
- Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de México (UNAM) Escuela Militar de Graduados de Sanidad, Universidad del Ejército y Fuerza Aérea, Mexico
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7
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Gómez-Zamudio JH, Villalobos-Molina R. Adventitia removal does not modify the α1D-adrenoceptors response in aorta during hypertension and ageing. ACTA ACUST UNITED AC 2009; 29:117-33. [DOI: 10.1111/j.1474-8673.2009.00432.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Conotoxins: molecular and therapeutic targets. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2009; 46:45-65. [PMID: 19184584 DOI: 10.1007/978-3-540-87895-7_2] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Marine molluscs known as cone snails produce beautiful shells and a complex array of over 50,000 venom peptides evolved for prey capture and defence. Many of these peptides selectively modulate ion channels and transporters, making them a valuable source of new ligands for studying the role these targets play in normal and disease physiology. A number of conopeptides reduce pain in animal models, and several are now in pre-clinical and clinical development for the treatment of severe pain often associated with diseases such as cancer. Less than 1% of cone snail venom peptides are pharmacologically characterised.
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Martínez-Salas SG, Campos-Peralta JM, Pares-Hipolito J, Gallardo-Ortíz IA, Ibarra M, Villalobos-Molina R. Alpha1A-adrenoceptors predominate in the control of blood pressure in mouse mesenteric vascular bed. ACTA ACUST UNITED AC 2007; 27:137-42. [PMID: 17584443 DOI: 10.1111/j.1474-8673.2007.00403.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1 The pressor action of the alpha1A-adrenoceptor agonist, A61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl] methanesulfonamide) or the alpha1-adrenoceptor agonist phenylephrine, and their blockade by selective alpha1-adrenoceptor antagonists in the mouse isolated mesenteric vascular bed were evaluated. 2 A61603 showed a approximately 235-fold higher potency in elevating perfusion pressure in mesenteric bed compared to phenylephrine. 3 The alpha1A-adrenoceptor selective antagonist RS 100329 (5-methyl-3-[3-[4-[2-(2,2,2,-trifluoroethoxy) phenyl]-1-piperazinyl] propyl]-2,4-(1H)-pyrimidinedione), displaced with high affinity agonist concentration-response curves to the right in a concentration-dependent manner. 4 The alpha1D-adrenoceptor selective antagonist BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5] decane-7,9-dione), did not displace A61603 nor did it block the phenylephrine-induced pressor response. 5 The alpha1B/D-adrenoceptor alkylating antagonist chloroethylclonidine (CEC), caused a rightward shift of the phenylephrine concentration-response curve and reduced its maximum response; however, CEC only slightly modified A61603 evoked contraction. 6 The results indicate that the isolated mouse mesenteric vascular bed expresses alpha1A-adrenoceptors and suggest a very discrete role for 1B-adrenoceptors.
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Affiliation(s)
- S G Martínez-Salas
- Escuela Militar de Graduados de Sanidad, Universidad del Ejército y Fuerza Aérea, Secretaría de la Defensa Nacional, México, D.F
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Kamikihara SY, Mueller A, Lima V, Akinaga J, Nojimoto FD, Castilho A, Buratini J, Pupo AS. alpha1-Adrenoceptors in proximal segments of tail arteries from control and reserpinised rats. Naunyn Schmiedebergs Arch Pharmacol 2007; 376:117-26. [PMID: 17676312 DOI: 10.1007/s00210-007-0176-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2007] [Accepted: 06/28/2007] [Indexed: 10/23/2022]
Abstract
It has been recently shown that the supersensitivity of distal segments of the rat tail artery to phenylephrine after chemical sympathectomy with reserpine results from the appearance of alpha(1D)-adrenoceptors. It is known that both alpha(1A)- and alpha(1D)-adrenoceptors are involved in the contractions of proximal portions of the rat tail artery. Therefore, this study investigated whether sympathectomy with reserpine would induce supersensitivity in proximal segments of the rat tail artery, a tissue in which alpha(1D)-adrenoceptors are already functional. Proximal segments of tail arteries from reserpinised rats were three- to sixfold more sensitive to phenylephrine and methoxamine than were arteries from control rats (n = 6-2; p < 0.05). The imidazolines N-[5-(4,5-Dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulfonamide hydrobromide (A-61603) and oxymetazoline, which activate selectively alpha(1A)-adrenoceptors, were equipotent in tail arteries from control and reserpinised rats (n = 4-2; p < 0.05), whereas buspirone, which activates selectively alpha(1D)-adrenoceptor, was approximately 4-fold more potent in tail arteries from reserpinised rats (n = 4-6; p < 0.05). Prazosin (nonselective) and 5-methylurapidil (alpha(1A)-selective), were competitive antagonists of contractions induced by phenylephrine and were equipotent in tail arteries from control and reserpinised rats (n = 4-6). The selective alpha(1D)-adrenoceptor antagonist 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5]decane-7,9-dione dihydrochloride (BMY-7378) presented similar complex antagonism in tail arteries from control and reserpinised rats, with Schild slopes much lower than 1.0 (p < 0.05, n = 4-6). Semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) revealed that mRNA encoding alpha(1A)-and alpha(1B)-adrenoceptors are similarly distributed in tail arteries from control and reserpinised rats, whereas mRNA for alpha(1D)-adrenoceptors is twice more abundant in the tail artery from reserpinised rats. In conclusion, the supersensitivity induced by reserpine is related only to alpha(1D)-adrenoceptors, even in tissues where this receptor subtype is already present and functional. Only the use of subtype-selective alpha(1)-adrenoceptor agonists detected the increased alpha(1D)-adrenoceptor component after reserpinisation, as the antagonists behaved similarly in tail arteries from control and reserpinised rats.
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MESH Headings
- Adrenergic alpha-1 Receptor Agonists
- Adrenergic alpha-1 Receptor Antagonists
- Animals
- Arteries/drug effects
- Arteries/innervation
- Arteries/metabolism
- Buspirone/pharmacology
- Gene Expression
- Imidazoles/pharmacology
- In Vitro Techniques
- Male
- Methoxamine/pharmacology
- Muscle Contraction/drug effects
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Oxymetazoline/pharmacology
- Phenylephrine/pharmacology
- Piperazines/pharmacology
- Prazosin/pharmacology
- RNA, Messenger/biosynthesis
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/biosynthesis
- Reserpine/pharmacology
- Reverse Transcriptase Polymerase Chain Reaction
- Sympathectomy
- Tail/blood supply
- Tetrahydronaphthalenes/pharmacology
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Affiliation(s)
- Susana Y Kamikihara
- Department of Pharmacology, Instituto de Biociências, UNESP, Botucatu, SP 18618-000, Brazil
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11
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Parés-Hipólito J, Gómez-Zamudio JH, Gallardo-Ortiz IA, López-Guerrero JJ, Santamaría-Ortiz J, Ibarra M, Villalobos-Molina R. Selective agonists reveal ?1A- and ?1B-adrenoceptor subtypes in caudal artery of the young rat. ACTA ACUST UNITED AC 2006; 26:371-8. [PMID: 16968476 DOI: 10.1111/j.1474-8673.2006.00380.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Multiple alpha(1)-adrenoceptors were evaluated in caudal artery of the young Wistar rat using selective agonists and antagonists. Arteries were exposed to the selective alpha(1A)-adrenoceptor agonist, A-61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl] methanesulfonamide) or to phenylephrine and to prazosin (alpha(1)-adrenoceptor antagonist), or the selective alpha(1A)-adrenoceptor antagonists 5-methylurapidil, RS 100329 (5-methyl-3-[3-[4-[2-(2,2,2,-trifluoroethoxy)phenyl]-1-piperazinyl]propyl]-2,4-(1H)-pyrimidinedione), RS 17053 (N-[2(2-cyclopropylmethoxy) ethyl]-5-chloro-alpha, alpha-dimethyl-1H-indole-3-ethanamide), and the selective alpha(1D)-adrenoceptor antagonist BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5] decane-7,9-dione). Results showed a 100-fold higher potency of A-61603 for the alpha(1)-adrenoceptor present in the artery, compared with phenylephrine. Prazosin displaced both agonists with high affinity, whereas 5-methylurapidil, RS 100329 and RS 17053 displaced A-61603 with high affinity, indicating the presence of alpha(1A)-adrenoceptors. The selective alpha(1A)-adrenoceptor antagonists blocked phenylephrine responses with low affinity, suggesting that phenylephrine activated a second receptor population in caudal artery. BMY 7378 antagonized with low affinity both A-61603 and phenylephrine-induced contractions, indicating absence of alpha(1D)-adrenoceptors in the vessel. The results suggest that functional alpha(1B)-adrenoceptors are present in caudal arteries of the young Wistar rat.
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Affiliation(s)
- J Parés-Hipólito
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados-Sede Sur, Mexico, D.F
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Kennedy WB, Crane L, Gonzalez RR, George OK, Edwards LP. Centrally Acting Imidazolines Stimulate Vascular Alpha 1A-Adrenergic Receptors in Rat-Tail Artery. Cell Mol Neurobiol 2006; 26:645-57. [PMID: 16897362 DOI: 10.1007/s10571-006-9109-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Accepted: 06/26/2006] [Indexed: 01/02/2023]
Abstract
: 1. Centrally acting imidazoline antihypertensive agents clonidine and moxonidine also act peripherally to contract blood vessels. While these agents act at both I(1)-imidazoline and alpha 2 adrenergic receptors centrally, the receptor types by which they mediate contraction require further definition. We therefore characterized the receptor subtype by which these agents mediate contraction of proximal rat-tail artery. 2. Dose-response curves were determined for phenylephrine and for several imidazoline ligands, using endothelium denuded, isolated ring segments, of tail arteries from adult male Sprague-Dawley rats. Ring segments were mounted on a force transducer with platinum wires and immersed in a tissue bath containing Krebs solution, to which drugs could be added. Signals were digitized and recorded by a computer. 3. Tail artery contractions expressed as a percent of contraction to 106 mM potassium were phenylephrine (96%), moxonidine (88%), clonidine (52%), and UK14304 (30%). Neither rilmenidine nor harmane caused contraction. Contraction of tail artery to moxonidine or clonidine could be blocked by alpha 1 antagonist urapidil or prazosin, and also by alpha 1A subtype selective antagonist WB4101. Schild plots were generated and a calculated pA2 value of 9.2 for prazosin in the presence of clonidine confirms clonidine as an agonist at alpha 1A receptors in proximal segments of rat-tail artery. 4. Our work suggests that clonidine and moxonidine are promiscuous compounds at micromolar concentrations and that harmane and rilmenidine are more selective compounds for in vivo imidazoline research.
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Affiliation(s)
- Wentsworth B Kennedy
- Department of Pharmacology/Physiology, Loma Linda University, Risley Hall, 110421 Campus Street, Loma Linda, California 92350, USA
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Chen L, Hodges RR, Funaki C, Zoukhri D, Gaivin RJ, Perez DM, Dartt DA. Effects of alpha1D-adrenergic receptors on shedding of biologically active EGF in freshly isolated lacrimal gland epithelial cells. Am J Physiol Cell Physiol 2006; 291:C946-56. [PMID: 16760267 PMCID: PMC2151204 DOI: 10.1152/ajpcell.00014.2006] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Transactivation of EGF receptors by G protein-coupled receptors is a well-known phenomenon. This process involves the ectodomain shedding of growth factors in the EGF family by matrix metalloproteinases. However, many of these studies employ transformed and/or cultured cells that overexpress labeled growth factors. In addition, few studies have shown that EGF itself is the growth factor that is shed and is responsible for transactivation of the EGF receptor. In this study, we show that freshly isolated, nontransformed lacrimal gland acini express two of the three known alpha(1)-adrenergic receptors (ARs), namely, alpha(1B)- and alpha(1D)-ARs. Alpha(1D)-ARs mediate phenylephrine (an alpha(1)-adrenergic agonist)-induced protein secretion and activation of p42/p44 MAPK, because the alpha(1D)-AR inhibitor BMY-7378, but not the alpha(1A)-AR inhibitor 5-methylurapidil, inhibits these processes. Activation of p42/p44 MAPK occurs through transactivation of the EGF receptor, which is inhibited by the matrix metalloproteinase ADAM17 inhibitor TAPI-1. In addition, phenylephrine caused the shedding of EGF from freshly isolated acini into the buffer. Incubation of freshly isolated cells with conditioned buffer from cells treated with phenylephrine resulted in activation of the EGF receptor and p42/p44 MAPK. The EGF receptor inhibitor AG1478 and an EGF-neutralizing antibody blocked this activation of p42/p44 MAPK. We conclude that in freshly isolated lacrimal gland acini, alpha(1)-adrenergic agonists activate the alpha(1D)-AR to stimulate protein secretion and the ectodomain shedding of EGF to transactivate the EGF receptor, potentially via ADAM17, which activates p42/p44 MAPK to negatively modulate protein secretion.
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Affiliation(s)
- LiLi Chen
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, MA
| | - Robin R. Hodges
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, MA
- * Address correspondence to: Robin R. Hodges, Schepens Eye Research Institute, 20 Staniford Street, Boston, MA 02114. Tel: 617-912-7424; FAX: 617-912-0104;
| | - Chika Funaki
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, MA
| | - Driss Zoukhri
- Tufts University School of Dental Medicine, Boston, MA
| | | | - Dianne M. Perez
- Lerner Research Institute, The Cleveland Clinic, Cleveland, OH
| | - Darlene A. Dartt
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, MA
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