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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 PMCID: PMC6592863 DOI: 10.1111/bph.14617] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [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 PharmacologyInstituto de Biociências, UNESPBotucatuBrazil
| | - J. Adolfo García‐Sáinz
- Instituto de Fisiología CelularUniversidad Nacional Autónoma de MéxicoCiudad de MéxicoMexico
| | - André S. Pupo
- Department of PharmacologyInstituto de Biociências, UNESPBotucatuBrazil
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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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Mueller A, Kiguti LRA, Silva EJR, Pupo AS. Contractile Effects of Serotonin (5-HT) in the Rat Cauda Epididymis: Expression and Functional Characterization of 5-HT Receptors. J Pharmacol Exp Ther 2019; 369:98-106. [PMID: 30728250 DOI: 10.1124/jpet.118.254110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 01/28/2019] [Indexed: 11/22/2022] Open
Abstract
Serotonin [5-hydroxytryptamine (5-HT)] exerts multiple central and peripheral functions. High concentrations of 5-HT have been found in the epididymis, a ductal organ that plays pivotal roles in sperm transport and maturation. The contraction of the epididymal smooth muscle is essential for sperm transport and emission during ejaculation. The contributions of the epididymal 5-HT system to these events are poorly understood. Here, we assessed the contractile function of 5-HT in the rat cauda epididymis (CE), pharmacologically targeting the receptor(s) and the reuptake mechanism involved in this system. Segments of CE duct from adult Wistar rats were set up in an organ bath system for isometric tension recordings, and concentration-response curves to 5-HT and norepinephrine were obtained. 5-HT elicited concentration-dependent contractions of the CE duct (pEC50 = 6.5 ± 0.1) that were potentiated with high potency by the norepinephrine transporter (NET) inhibitor desipramine and with low potency by the highly selective serotonin transporter inhibitor paroxetine, indicating that the NET is the major mediator of 5-HT reuptake in vitro. CE contractions to 5-HT were antagonized by the α 1-adrenoceptor (α 1-AR) antagonist prazosin (pA 2 ≅ 8.9), 5-HT2A/2C antagonists ketanserin (pA 2 ≅ 9.4) and fluoxetine (pA 2 ≅ 7.4), and 5-HT1A ligands WAY 100635 (pA 2 ≅ 8.9) and buspirone (pA 2 ≅ 7.3). Reverse transcriptase polymerase chain reaction analysis demonstrated that 5-HT1A and 5-HT2A transcripts are highly abundant in the cauda epididymis, whereas 5-HT2C transcript was not found. Altogether, our results reveal that contractions of the CE duct to 5-HT encompasses at least activation of α 1-ARs and 5-HT1A and 5-HT2A receptors, providing new insights into the roles of 5-HT on the epididymal function.
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Affiliation(s)
- Andre Mueller
- Department of Pharmacology, Institute of Biosciences, São Paulo State University, Botucatu-São Paulo, Brazil
| | - Luiz R A Kiguti
- Department of Pharmacology, Institute of Biosciences, São Paulo State University, Botucatu-São Paulo, Brazil
| | - Erick J R Silva
- Department of Pharmacology, Institute of Biosciences, São Paulo State University, Botucatu-São Paulo, Brazil
| | - André S Pupo
- Department of Pharmacology, Institute of Biosciences, São Paulo State University, Botucatu-São Paulo, Brazil
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Pacini ESA, Castilho ACS, Hebeler-Barbosa F, Pupo AS, Kiguti LRA. Contraction of Rat Cauda Epididymis Smooth Muscle to α1-Adrenoceptor Activation Is Mediated by α1A-Adrenoceptors. J Pharmacol Exp Ther 2018; 366:21-28. [PMID: 29685886 DOI: 10.1124/jpet.117.246710] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 04/16/2018] [Indexed: 01/07/2023] Open
Abstract
The cauda epididymis (CE), the site of sperm storage until the ejaculation, is densely innervated by the sympathetic nervous system. Contraction of CE smooth muscle via α1-adrenoceptors (α1-ARs) plays a key role during the seminal emission phase of ejaculation and α1-AR antagonism has been suggested as a nonhormonal and reversible male contraceptive target. Since the α1-AR subtype mediating contraction of rat CE is not known, this study investigates the expression and role of α1-AR subtypes on the proximal and distal rat CE duct contraction to norepinephrine in vitro. Alpha1a, α1b, and α1d transcripts were detected by real-time quantitative polymerase chain reaction in proximal and distal CE segments and α1a and α1d were shown to predominate over α1b The inhibition of [3H]prazosin specific binding to intact CE segments from proximal and distal CE by RS 100329 and 5-methylurapidil (α1A-selective) and BMY 7378 (α1D-selective) showed that α1A- and α1D-ARs are expressed at similar densities. Norepinephrine-induced contractions of CE were competitively antagonized with high affinity by RS 100329 (pKB ≈ 9.50) and 5-methylurapidil (pKB ≈ 9.0) and with low affinity by BMY 7378 (pKB ≈ 7.0) and the α1B-selective L-765,314 (pA2 < 7.0), suggesting contractions are mediated by α1A-ARs. The clinically used α1A/D-ARs antagonist tamsulosin potently (pA2 ≈ 10.0) inhibited the norepinephrine-induced CE contractions. Altogether, our results show that α1A- and α1D-ARs are expressed in the CE duct and α1A-AR is the main subtype mediating contraction to norepinephrine. Our results highlight the importance of α1A-AR in the peripheral control of ejaculation and strengthen the α1A-AR as a target for a nonhormonal approach to male contraception.
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Affiliation(s)
- Enio S A Pacini
- Department of Pharmacology, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Anthony C S Castilho
- Department of Pharmacology, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Flavia Hebeler-Barbosa
- Department of Pharmacology, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
| | - André S Pupo
- Department of Pharmacology, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
| | - Luiz R A Kiguti
- Department of Pharmacology, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil
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Bomfim GHS, García García A, Jurkiewicz A, Jurkiewicz NH. Relationship between central behavioral effects and peripheral sympathetic neurotransmission functionality during acute cocaine withdrawal syndrome in adult rats. THE AMERICAN JOURNAL OF DRUG AND ALCOHOL ABUSE 2015; 42:63-76. [PMID: 26579734 DOI: 10.3109/00952990.2015.1094082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Acute cocaine withdrawal syndrome (ACWS) is characterized as a set of organic alterations triggered by abrupt discontinuation of chronic cocaine consumption, usually occurring at 24-40 hours after withdrawal. However, little is known about the relationship between central and peripheral sympathetic neurotransmission during ACWS. OBJECTIVE AND METHODS We investigated the mechanisms involved in central and peripheral sympathetic neurotransmission and how ACWS affects the sympathetic functionality. Cocaine was administered twice daily for 5 days in Wistar rats (at least 5 in each group): on the first and second day, 15 mg/kg/i.p.; third day, 20 mg/kg/i.p.; and finally in the last two days, 30 mg/kg/i.p. Subsequently, at 1, 24, 48 and 120 h after cocaine administration the following experiments were done: (i) at the central level, behavioral tests of open-field and elevated plus maze; and (ii) at the peripheral level, tests of catecholamine release, function of α2-adrenergic receptors (α2-ARs), imidazoline receptors (I(1,2)-Rs), L-type voltage-gated (Ca(v1.2)) Ca(2+) channels and α1-ARs. RESULTS During ACWS, rats showed hypolocomotion and exacerbation of anxiogenic-effects 24 h after cocaine withdrawal. Likewise, a decrease in the catecholamine release and activity of α2-ARs/I(1,2)-Rs at 24-48 h after cocaine withdrawal was observed. A decrease in Ca(v1.2) channels and α1-ARs function at 48 h after cocaine withdrawal was observed. CONCLUSIONS The relationship of central and peripheral sympathetic neurotransmission during ACWS possibly due to a failure in activation and/or inactivation of presynaptic α2-ARs/I(1,2)-Rs, may offer a potential target for attenuating ACWS.
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Affiliation(s)
| | - Antonio García García
- b Instituto Teófilo Hernando del Medicamento , Universidad Autónoma de Madrid , Madrid , Spain
| | - Aron Jurkiewicz
- a Department of Pharmacology , Escola Paulista de Medicina, Universidade Federal de São Paulo , Brazil
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Jurkiewicz NH, Caricati-Neto A, Verde LF, Honda L, da Silva Junior ED, Reuter HR, Jurkiewicz A, Avellar MCW. Could α1-adrenoceptors and androgen receptors be modified by sexual maturation and testosterone in the rat testicular capsule? Life Sci 2015; 141:212-20. [DOI: 10.1016/j.lfs.2015.09.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 07/08/2015] [Accepted: 09/10/2015] [Indexed: 10/23/2022]
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Bomfim GHS, Verde LF, Frussa-Filho R, Jurkiewicz A, Jurkiewicz NH. Functional effects of alcohol withdrawal syndrome on peripheral sympathetic neurotransmission in vas deferens of adult rats. Life Sci 2014; 108:34-43. [PMID: 24831557 DOI: 10.1016/j.lfs.2014.05.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 04/14/2014] [Accepted: 05/02/2014] [Indexed: 01/19/2023]
Abstract
AIMS Alcohol withdrawal syndrome (AWS) is characterized by a set of physiological modifications triggered by abrupt withdrawal and/or decreasing consumption of ethanol (EtOH), which may manifest 16-48 h after ceasing consumption. The relationship between the effects of AWS and central and peripheral sympathetic neurotransmission is unknown. This study investigates the possible mechanisms on the sympathetic system during periods of AWS. MAIN METHODS Male Wistar rats were treated with EtOH (6-10 g/kg/day/v.o. 5 days). Subsequently, 1h, 24h, 48 h and 120 h after administration of the last dose of EtOH, the animals were sacrificed, and their vas deferens (VD) were removed to perform the following evaluations: (a) concentration-effect curves of sympathetic agonist; (b) activity of α2-adrenoreceptor; (c) function of voltage-dependent calcium channels (Cav); and (d) release of endogenous catecholamines measured in real time coupled to HPLC. KEY FINDINGS The results showed that the maximum effects of contraction were increased by agonists tested in at 24h and 48 h EtOH withdrawal. The inhibitory affinity (pIC50) of guanfacine was decreased 24h EtOH withdrawal. The function of Cav was also decreased as pIC50 values dropped 24h and 48 h EtOH withdrawal. The release of catecholamines increased 48 h after EtOH withdrawal. It is suggested that AWS triggers hyperactivity in peripheral sympathetic neurotransmission. SIGNIFICANCE The mechanisms underlying hyperactivity are possibly explained by a failure of autoregulation from catecholamines released by α2-adrenoreceptors and/or an increase of Cav function, which may be potential targets to attenuate the symptoms of AWS at the peripheral level.
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Affiliation(s)
| | - Luciana Ferreira Verde
- Department of Pharmacology, Federal University of São Paulo (Unifesp), Rua 3 de maio 100, 04044-020 São Paulo, SP, Brazil
| | - Roberto Frussa-Filho
- Department of Pharmacology, Federal University of São Paulo (Unifesp), Rua 3 de maio 100, 04044-020 São Paulo, SP, Brazil
| | - Aron Jurkiewicz
- Department of Pharmacology, Federal University of São Paulo (Unifesp), Rua 3 de maio 100, 04044-020 São Paulo, SP, Brazil.
| | - Neide Hyppolito Jurkiewicz
- Department of Pharmacology, Federal University of São Paulo (Unifesp), Rua 3 de maio 100, 04044-020 São Paulo, SP, Brazil
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8
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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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de Almeida Kiguti LR, Pupo AS. Investigation of the Effects of α1‐Adrenoceptor Antagonism and L‐Type Calcium Channel Blockade on Ejaculation and Vas Deferens and Seminal Vesicle Contractility In Vitro. J Sex Med 2012; 9:159-68. [DOI: 10.1111/j.1743-6109.2011.02410.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Avellar MCW, Lázari MFM, Porto CS. Expression and function of G-protein-coupled receptorsin the male reproductive tract. AN ACAD BRAS CIENC 2009; 81:321-44. [DOI: 10.1590/s0001-37652009000300002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2008] [Accepted: 08/14/2008] [Indexed: 11/22/2022] Open
Abstract
This review focuses on the expression and function of muscarinic acetylcholine receptors (mAChRs), α1-adrenoceptors and relaxin receptors in the male reproductive tract. The localization and differential expression of mAChR and α1-adrenoceptor subtypes in specific compartments of the efferent ductules, epididymis, vas deferens, seminal vesicle and prostate of various species indicate a role for these receptors in the modulation of luminal fluid composition and smooth muscle contraction, including effects on male fertility. Furthermore, the activation of mAChRs induces transactivation of the epidermal growth factor receptor (EGFR) and the Sertoli cell proliferation. The relaxin receptors are present in the testis, RXFP1 in elongated spermatids and Sertoli cells from rat, and RXFP2 in Leydig and germ cells from rat and human, suggesting a role for these receptors in the spermatogenic process. The localization of both receptors in the apical portion of epithelial cells and smooth muscle layers of the vas deferens suggests an involvement of these receptors in the contraction and regulation of secretion.
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11
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Effects of swimming and nandrolone decanoate treatment on vas deferens response to norepinephrine. Life Sci 2009; 85:541-5. [DOI: 10.1016/j.lfs.2009.08.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Revised: 08/03/2009] [Accepted: 08/13/2009] [Indexed: 11/20/2022]
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12
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Nojimoto FD, Piffer RC, Kiguti LRDA, Lameu C, de Camargo ACM, Pereira OCM, Pupo AS. Multiple effects of sibutramine on ejaculation and on vas deferens and seminal vesicle contractility. Toxicol Appl Pharmacol 2009; 239:233-40. [PMID: 19482040 DOI: 10.1016/j.taap.2009.05.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 05/19/2009] [Accepted: 05/22/2009] [Indexed: 11/25/2022]
Abstract
Sibutramine is an inhibitor of norepinephrine and 5-HT reuptake largely used in the management of obesity. Although a fairly safe drug, postmarketing adverse effects of sibutramine were reported including abnormal ejaculation in men. This study investigates the effects of sibutramine on ejaculation and vas deferens and seminal vesicle contractility. Adult male rats received sibutramine (5; 20; or 50 mg kg(-1), ip) and after 60 min were exposed to receptive females for determination of ejaculation parameters. The vasa deferentia and seminal vesicles of untreated rats were mounted in isolated organ baths for recording of isometric contractions and HEK293 cells loaded with fluorescent calcium indicator were used to measure intracellular Ca(2+) transients. Sibutramine 5 and 20 mg kg(-1) reduced ejaculation latency whereas 50 mg kg(-1) increased ejaculation latency. Sibutramine 3 to 30 microM greatly increased the sensitivity of the seminal vesicle and vas deferens to norepinephrine, but at concentrations higher than 10 microM there were striking depressions of maximal contractions induced by norepinephrine, carbachol and CaCl(2). In HEK293 cells, sibutramine 10 to 100 microM inhibited intracellular Ca(2+) transients induced by carbachol. Depending on the doses, sibutramine either facilitates or inhibits ejaculation. Apart from its actions in the central nervous system, facilitation of ejaculation may result from augmented sensitivity of smooth muscles to norepinephrine while reductions of intracellular Ca(2+) may be involved in the delayed ejaculation observed with high doses of sibutramine.
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Affiliation(s)
- Fernanda D Nojimoto
- Department of Pharmacology, Instituto de Biociências, UNESP, Botucatu, SP 18618000, Brazil
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Yono M, Latifpour J, Yamamoto Y, Imanishi A, Yoshida M. Region and age dependent differences in α1-adrenergic responsiveness of rat seminal vesicle and vas deferens. Eur J Pharmacol 2008; 587:291-5. [DOI: 10.1016/j.ejphar.2008.04.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 03/19/2008] [Accepted: 04/02/2008] [Indexed: 11/17/2022]
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Queiróz DBC, Porto CS, Grossman G, Petrusz P, Avellar MCW. Immunolocalization of alpha(1A)-adrenoceptors in rat and human epididymis. Cell Tissue Res 2008; 332:509-22. [PMID: 18351393 DOI: 10.1007/s00441-008-0576-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Accepted: 01/09/2008] [Indexed: 11/30/2022]
Abstract
Immunohistochemistry was conducted to analyze the cellular localization of alpha(1A)-adrenoceptors along rat and human epididymis. ADR-A, a polyclonal antibody that recognizes the specific C-terminal region of alpha(1A)-adrenoceptors, immunostained this adrenoceptor subtype in smooth muscle cells surrounding the epididymal tubules and interstitial blood vessels and in subpopulations of epithelial cells from adult rat and human caput and cauda epididymidis. The same cell types from rat epididymidis were immunostained by ADR-1, a polyclonal antibody that recognizes a common region of the three alpha(1)-adrenoceptor subtypes, alpha(1A), alpha(1B), and alpha(1D). Immunostaining with both antibodies was also conducted in adult rat and human vas deferens and seminal vesicle used as positive controls because of the abundance of alpha(1A)-adrenoceptors in these tissues. ADR-A- and ADR-1-positive immunostaining was differentially distributed depending on the antibody, method of tissue fixation (Bouin-fixed and fresh frozen tissues), species (rat and human), tissue (caput and cauda epididymidis), and age (immature and adult rats) analyzed. This is the first report immunolocalizing alpha(1A)-adrenoceptor along rat and human epididymis. The presence of this adrenoceptor subtype in epididymal smooth muscle and epithelial cells indicates their contribution to smooth muscle contractile responses and a possible role in the absorptive and/or secretory activities of the epithelium lining the epididymal duct. Taken together, our results should contribute to a better understanding of the physiological role of alpha(1)-adrenoceptors in the epididymidis and the importance of the sympathetic nervous system for male (in)fertility.
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Affiliation(s)
- Daniel Barboza Cava Queiróz
- Section of Experimental Endocrinology, Department of Pharmacology, Universidade Federal de São Paulo Escola Paulista de Medicina, INFAR, Vila Clementino, São Paulo, Brazil
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Brock JA, Handelsman DJ, Keast JR. Postnatal androgen deprivation dissociates the development of smooth muscle innervation from functional neurotransmission in mouse vas deferens. J Physiol 2007; 581:665-78. [PMID: 17379637 PMCID: PMC2075184 DOI: 10.1113/jphysiol.2007.128728] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The pelvic autonomic nervous system is a target for circulating androgens in adults, with androgen exposure or deprivation affecting the structure and function of urogenital tract innervation. However, the critical period for androgen exposure to initially establish pelvic autonomic neuromuscular transmission has not been determined. We have examined the sympathetic innervation of the vas deferens in hypogonadal (hpg) mice that are deprived of androgens after birth but undergo normal prenatal sexual differentiation and remain androgen responsive throughout life. In vasa deferentia from hpg mice, purinergic excitatory junction potentials and contractions could not be elicited by electrical stimulation and P2X(1) purinoceptors could not be demonstrated by immunofluorescence. Moreover, a novel inhibitory nitrergic transmission developed. Administering testosterone to adult hpg mice restored purinergic excitatory transmission and P2X(1) purinoceptor immunofluorescence, and nitrergic inhibitory transmission was lost. Despite the deficit in excitatory neurotransmission in hpg mice, their vasa deferentia were innervated by numerous noradrenergic axons and pelvic ganglia appeared normal. In addition, noradrenergic contractions could be elicited by electrical stimulation. This study has revealed that postnatal androgen exposure has a profound effect on the development of excitatory transmission in vas deferens smooth muscle, primarily by a postjunctional action, but is not essential for development of the structural innervation of this organ. Our results also indicate that there is no postnatal critical period for androgen exposure to establish neuroeffector transmission and that postnatal androgen exposure can be delayed until adulthood, with little consequence for establishment of normal sympathetic neurotransmission.
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Affiliation(s)
- J A Brock
- Prince of Wales Medical Research Institute, University of New South Wales, Randwick, NSW 2031, Australia
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16
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Pereira OCM, Piffer RC. Puberty installation and adrenergic response of seminal vesicle from rats exposed prenatally to hydrocortisone. Life Sci 2005; 77:1381-90. [PMID: 15893772 DOI: 10.1016/j.lfs.2005.04.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Accepted: 04/04/2005] [Indexed: 10/25/2022]
Abstract
We investigated the effects of hydrocortisone during the prenatal period and its repercussion on puberty installation and adrenergic response of seminal vesicle in adult rats. The efficacy of the hydrocortisone treatment in reducing adrenal wet weight immediately after delivery in both the treated mothers and respective pups at birth may indicate impairment of the hypothalamus--pituitary--adrenal axis. This parameter was unchanged in the adult phase of these descendants, suggesting recuperation of this axis. In addition, the treatment with hydrocortisone delayed the age of puberty installation, probably by absence of both physiologic production and liberation of luteinizing hormone and testosterone. Despite the significant reduction in testosterone level as well as of wet weights of both vas deferens and testis in the adult phase, no difference was observed in the sensitivity of the seminal vesicle to the studied sympathetic agonist. However, the observed reduction in contractile response of the seminal vesicle may be a consequence of contractile-system damage in this organ. It is possible that this alteration may cause a reduction in the amount of vesicular secretion so important in the process of ejaculation. In conclusion, these results suggest that administration of hydrocortisone in late prenatal life did not influence the hypothalamus--pituitary--adrenal axis in adult life, although it altered the hypothalamus--pituitary--gonadal axis, and reduced testosterone production starting at puberty, as a consequence of an incomplete masculinization of the hypothalamus plus a reduction in the contractile response of the seminal vesicle.
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17
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Lima V, Mueller A, Kamikihara SY, Raymundi V, Alewood D, Lewis RJ, Chen Z, Minneman KP, Pupo AS. Differential antagonism by conotoxin rho-TIA of contractions mediated by distinct alpha1-adrenoceptor subtypes in rat vas deferens, spleen and aorta. Eur J Pharmacol 2005; 508:183-92. [PMID: 15680270 DOI: 10.1016/j.ejphar.2004.12.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2004] [Revised: 12/01/2004] [Accepted: 12/06/2004] [Indexed: 11/16/2022]
Abstract
The ability of the conotoxin rho-TIA, a 19-amino acid peptide isolated from the marine snail Conus tulipa, to antagonize contractions induced by noradrenaline through activation of alpha1A-adrenoceptors in rat vas deferens, alpha1B-adrenoceptors in rat spleen and alpha1D-adrenoceptors in rat aorta, and to inhibit the binding of [125I]HEAT (2-[[beta-(4-hydroxyphenyl)ethyl]aminomethyl]-1-tetralone) to membranes of human embryonic kidney (HEK) 293 cells expressing each of the recombinant rat alpha1-adrenoceptors was investigated. rho-TIA (100 nM to 1 microM) antagonized the contractions of vas deferens and aorta in response to noradrenaline without affecting maximal effects and with similar potencies (pA2 approximately 7.2, n=4). This suggests that rho-TIA is a competitive antagonist of alpha1A- and alpha1D-adrenoceptors with no selectivity between these subtypes. Incubation of rho-TIA (30 to 300 nM) with rat spleen caused a significant reduction of the maximal response to noradrenaline, suggesting that rho-TIA is a non-competitive antagonist at alpha1B-adrenoceptors. After receptor inactivation with phenoxybenzamine, the potency of rho-TIA in inhibiting contractions was examined with similar occupancies (approximately 25%) at each subtype. Its potency (pIC50) was 12 times higher in spleen (8.3+/-0.1, n=4) than in vas deferens (7.2+/-0.1, n=4) or aorta (7.2+/-0.1, n=4). In radioligand binding assays, rho-TIA decreased the number of binding sites (B(max)) in membranes from HEK293 cells expressing the rat alpha1B-adrenoceptors without affecting affinity (K(D)). In contrast, in HEK293 cells expressing rat alpha1A- or alpha1D-adrenoceptors, rho-TIA decreased the K(D) without affecting the B(max). It is concluded that rho-TIA will be useful for distinguishing the role of particular alpha1-adrenoceptor subtypes in native tissues.
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Affiliation(s)
- Vanessa Lima
- Department of Pharmacology, Instituto de Biociências, UNESP, Botucatu, SP 18618-000, Brazil
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18
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Mendes FR, Hamamura M, Queiróz DBC, Porto CS, Avellar MCW. Effects of androgen manipulation on α1-adrenoceptor subtypes in the rat seminal vesicle. Life Sci 2004; 75:1449-63. [PMID: 15240180 DOI: 10.1016/j.lfs.2004.03.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2003] [Accepted: 03/05/2004] [Indexed: 11/22/2022]
Abstract
This study analyses possible changes during surgical and chemical castration in the expression and pharmacological characteristics of alpha1-adrenoceptor in adult rat seminal vesicle. Ribonuclease protection assays indicated that alpha1a--was the predominant mRNA, while alpha1b-and alpha1d-adrenoceptor transcripts were detected in lower abundance in this tissue. alpha1a-adrenoceptor mRNA expression presented a complex dependency on androgens, while alpha1b- and alpha1d-adrenoceptor transcripts were both upregulated with surgical and chemical castration, suggesting a negative modulation by androgens. Testosterone treatment reversed the effects caused by surgical castration. Functional studies confirmed the involvement of alpha1A- and alpha1B-adrenoceptor in the seminal vesicle contractile responses, and suggested that alpha1B-induced contractile response was upregulated after castration. Taken together, the results suggest that alpha1-adrenoceptor expression in seminal vesicle is differentially regulated by the androgen status of the rat.
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Affiliation(s)
- Fúlvio R Mendes
- Department of Pharmacology, Section of Experimental Endocrinology, UNIFESP-Escola Paulista de Medicina, Rua 03 de maio 100, INFAR, Vila Clementino, 04044-020, São Paulo, Brazil
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19
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Campos M, Morais PL, Pupo AS. Effect of cyproterone acetate on alpha1-adrenoceptor subtypes in rat vas deferens. Braz J Med Biol Res 2003; 36:1571-81. [PMID: 14576912 DOI: 10.1590/s0100-879x2003001100015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gonadal hormones regulate the expression of alpha1-adrenoceptor subtypes in several tissues. The present study was carried out to determine whether or not cyproterone acetate, an anti-androgenic agent, regulates the alpha1-adrenoceptor subtypes that mediate contractions of the rat vas deferens in response to noradrenaline. The actions of subtype selective alpha1-antagonists were investigated in vas deferens from control and cyproterone acetate-treated rats (10 mg/day, sc, for 7 days). Prazosin (pA2 approximately 9.5), phentolamine (pA2 approximately 8.3) and yohimbine (pA2 approximately 6.7) presented competitive antagonism consistent with activation of alpha1-adrenoceptors in vas deferens from both control and treated rats. The pA2 values estimated for WB 4101 ( approximately 9.5), benoxathian ( approximately 9.7), 5-methylurapidil (approximately 8.5), indoramin ( approximately 8.7) and BMY 7378 ( approximately 6.8) indicate that alpha1A-adrenoceptors are involved in the contractions of the vas deferens from control and cyproterone acetate-treated rats. Treatment of the vas deferens from control rats with the alpha1B/alpha1D-adrenoceptor alkylating agent chloroethylclonidine had no effect on noradrenaline contractions, supporting the involvement of the alpha1A-subtype. However, this agent partially inhibited the contractions of vas deferens from cyproterone acetate-treated rats, suggesting involvement of multiple receptor subtypes. To further investigate this, the actions of WB 4101 and chloroethylclonidine were reevaluated in the vas deferens from rats treated with cyproterone acetate for 14 days. In these organs WB 4101 presented complex antagonism characterized by a Schild plot with a slope different from unity (0.65 0.05). After treatment with chloroethylclonidine, the complex antagonism presented by WB 4101 was converted into classical competitive antagonism, consistent with participation of alpha1A-adrenoceptors as well as alpha1B-adrenoceptors. These results suggest that cyproterone acetate induces plasticity in the alpha1-adrenoceptor subtypes involved in the contractions of the vas deferens.
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Affiliation(s)
- M Campos
- Departamento de Farmacologia, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, SP, Brasil
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20
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Morais PDL, Campos M, Pupo AS. Effects of castration on alpha 1-adrenoceptor subtypes in the rat aorta. Vascul Pharmacol 2003; 39:335-41. [PMID: 14567072 DOI: 10.1016/s1537-1891(03)00045-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The expression of alpha 1-adrenoceptor subtypes in several tissues is regulated by gonadal hormones. In this study, we investigated whether castration regulates the alpha 1-adrenoceptor subtypes mediating the contractions of the aorta from male rats to noradrenaline. Noradrenaline induced similar concentration-dependent contractions in the aorta from control and castrated rats. Treatment of the aorta from both control and castrated rats with the alpha 1B/alpha 1D-adrenoceptor alkylating agent chloroethylclonidine resulted in approximately 1600-fold rightward shift in the concentration-response curves to noradrenaline. The pA2 values found for WB 4101, benoxathian (alpha 1A-selective) and BMY 7378 (alpha 1D-selective) indicate that alpha 1D-adrenoceptors are involved in the contractions of the aorta from control and castrated rats to noradrenaline. However, there was a 15-fold difference between the pKB estimated through the lowest effective concentrations of the alpha 1A-adrenoceptor selective antagonist 5-methyl-urapidil in the aorta from control and castrated rats. The pKB estimated in aorta from control rats is consistent with the interaction with alpha 1D-adrenoceptors (7.58 +/- 0.06), while that calculated in organs from control rats is consistent with alpha 1A-adrenoceptors (8.76 +/- 0.09). These results suggest that castration induces plasticity in the alpha 1-adrenoceptor subtypes involved in the contractions of the aorta to noradrenaline.
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Affiliation(s)
- Paola de Lucena Morais
- Department of Pharmacology, Instituto de Biociências, UNESP, 18618-000 Botucatu, SP, Brazil
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21
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Uhlén S, Lindblom J, Kindlundh A, Mugisha P, Nyberg F. Nandrolone treatment decreases the level of rat kidney alpha(1B)-adrenoceptors. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2003; 368:91-8. [PMID: 12861436 DOI: 10.1007/s00210-003-0763-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2002] [Accepted: 04/18/2003] [Indexed: 10/26/2022]
Abstract
Abuse of anabolic androgenic steroids (AAS) is associated with serious side effects, such as hypertension and fluid retention. Renal alpha(1)- and alpha(2)-adrenoceptors are implicated in the regulation of blood pressure and fluid balance. In the present study, the levels of renal alpha(1A)-, alpha(1B)-, alpha(2A)- and alpha(2B)-adrenoceptors, and spleen alpha(1B)-adrenoceptors, were quantified in tissue membranes from rats treated with the AAS nandrolone decanoate (15 mg/kg) for 14 days. The radioligands used were [(3)H]-prazosin and [(3)H]-RX821002. The nandrolone treatment caused a 50% reduction of kidney alpha(1B)-adrenoceptors (from 15 fmol/mg protein in control rats to 6.5 fmol/mg protein in treated rats). In contrast, the levels of kidney alpha(1A)-, alpha(2A)- and alpha(2B)-, and spleen alpha(1B)-adrenoceptors were unaffected. These results raise the possibility that a decreased level of kidney alpha(1B)-adrenoceptors may cause some of the effects observed on blood pressure and fluid balance in heavy abuse of AAS.
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Affiliation(s)
- Staffan Uhlén
- Department of Pharmaceutical Biosciences, Uppsala University, Box 591 BioMedical Centre, 751 24 Uppsala, Sweden
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22
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Campos M, Morais PDL, Pupo AS. Effects of castration and of testosterone replacement on alpha(1)-adrenoceptor subtypes in the rat vas deferens. Eur J Pharmacol 2003; 471:149-55. [PMID: 12818703 DOI: 10.1016/s0014-2999(03)01822-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The contractions of the rat vas deferens in response to noradrenaline are mediated through alpha(1A)-adrenoceptors. We observed participation of alpha(1B)-adrenoceptors in these contractions after castration. We now investigated the time course of this plasticity and the effects of testosterone by determining the actions of competitive antagonists on noradrenaline-induced contractions after 7, 14, 21 and 30 days of castration. BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5]decane-7,9-dione dihydrochloride) antagonised noradrenaline-induced contractions in control and castrated rats with low pA(2) values (approximately = 6.8). In control vas deferens, WB 4101 (2-(2,6-dimethoxyphenoxyethyl)aminomethyl-1,4-benzodioxane hydrochloride) had a slope in the Schild plot no different from 1.0, while slopes lower than 1.0 (approximately 0.6) were observed for vas deferens from castrated rats. Chloroethylclonidine was ineffective in the control vas while it inhibited noradrenaline-induced contractions in vasa from castrated rats and converted the complex antagonism by WB 4101 into simple competitive antagonism. Treatment of castrated rats with testosterone prevented the effects of castration. The results suggest that alpha(1B)-adrenoceptors are detectable in vas deferens from at least the 7th through the 30th day after castration and that testosterone prevents this plasticity.
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Affiliation(s)
- Marcelo Campos
- Departmento de Farmacologia, Instituto de Biociências, UNESP, Botucatu, SP 18618-000, Brazil
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23
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Hayes ES, Adaikan PG. Metachlorophenylpiperazine (m-CPP) induced intracavernous pressure responses in anaesthetized rats. Int J Impot Res 2002; 14:287-94. [PMID: 12152119 DOI: 10.1038/sj.ijir.3900888] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2001] [Accepted: 04/25/2002] [Indexed: 11/09/2022]
Abstract
Here we have recorded the effects of metachlorophenylpiperazine (m-CPP) on intracavernous pressure (ICP) in anesthetized rats pretreated with various pharmacological agents in an attempt to determine the mechanism and relevance of the m-CPP induced ICP response to other models of erection. m-CPP elicited consistent and significantly greater increases in ICP (71.5+/-6.6 mmHg) compared with the mixed 5-HT(2a/2c) agonists trifluoromethylphenylpiperazine (3.4+/-1.3 mmHg) and quipazine (10.9+/-1.8 mmHg). Blockade of 5-HT(2a) receptors with ketanserin failed to unmask any stimulatory effect of quipazine (7.2+/-1.0 mmHg). m-CPP induced ICP responses (71+/-7.0 mmHg) were unaffected in the presence of mianserin (63+/-5 mmHg) and ketanserin (51+/-12 mmHg). Spiperone significantly reduced the m-CPP induced increase in ICP (8.0+/-1.0 mmHg). Naloxone, yohimbine and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OHDPAT) failed to elicit increases in ICP on their own. All three drugs significantly reduced the latency to the first m-CPP induced ICP response compared to saline. Yohimbine increased the duration of m-CPP induced ICP responses whereas 8-OHDPAT increased the mean number of m-CPP induced ICP responses compared to saline. The effects of m-CPP on ICP in anesthetized rats may not be mediated by 5-HT(2c) receptors and appears to be similar to erection in copula, but not erection elicited by other drugs or penile sheath retraction.
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Affiliation(s)
- E S Hayes
- Department of Obstetrics and Gynaecology, the National University of Singapore, Singapore.
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24
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Queiróz DBC, Mendes FR, Porto CS, Avellar MCW. Alpha1-adrenoceptor subtypes in rat epididymis and the effects of sexual maturation. Biol Reprod 2002; 66:508-15. [PMID: 11804969 DOI: 10.1095/biolreprod66.2.508] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
We have characterized the expression of alpha1-adrenoceptor in epididymis from rats in different stages of sexual maturation: 40 (immature), 60 (young adult), and 120 (adult) days of age. Plasma testosterone levels were low in the immature animals but increased significantly in the 60- and 120-day-old animals. These changes were followed by a progressive increase in rat body weight and in caput and cauda epididymis relative weight. Reverse transcription polymerase chain reaction assay indicated that alpha1a-, alpha1b-, and alpha1d-adrenoceptor transcripts were present in both caput and cauda epididymis from adult rats. Ribonuclease protection assays further indicated that the expression of these alpha1-adrenoceptor transcripts differed with age and epididymal region analyzed. Prazosin (nonselective alpha1 antagonist), 5-methyl urapidil (alpha1A-selective), and BMY 7378 (alpha1D-selective) displaced [3H]prazosin binding curves in caput and cauda epididymis from 40- and 120-day-old rats. The potency order for these antagonists, as calculated from the negative logarithm of the inhibition constant (pK(i)) values for the high-affinity sites, indicated a predominant population of alpha1A-adrenoceptor subtype in caput and cauda epididymis from adult animals. Differences in pK(i) values in caput and cauda epididymis from immature and adult animals also suggested that the relative amount of alpha1-adrenoceptors, at the protein level, is modulated by sexual maturation. Taken together, the changes in alpha1-adrenoceptor expression during sexual maturation may suggest specific roles for these receptors in epididymal function.
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MESH Headings
- Adrenergic alpha-Antagonists/metabolism
- Animals
- Binding, Competitive
- Epididymis/drug effects
- Epididymis/metabolism
- In Situ Hybridization
- Male
- Membranes/drug effects
- Membranes/metabolism
- Nuclease Protection Assays
- Organ Size/drug effects
- Organ Size/physiology
- Prazosin/metabolism
- RNA, Messenger/biosynthesis
- RNA, Messenger/isolation & purification
- Radioligand Assay
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-1/biosynthesis
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sexual Maturation/physiology
- Testosterone/blood
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Affiliation(s)
- Daniel B C Queiróz
- Section of Experimental Endocrinology, Department of Pharmacology, Universidade Federal de São Paulo-Escola Paulista de Medicina, 04044-020 São Paulo, Brazil
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25
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Silva MA, Megale A, Avellar MC, Porto CS. Expression and pharmacological characterization of alpha1-adrenoceptors in rat seminal vesicle. Eur J Pharmacol 1999; 381:141-9. [PMID: 10554882 DOI: 10.1016/s0014-2999(99)00563-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the present study, we investigated the alpha1-adrenoceptor subtypes mediating adrenaline-induced contractions of the rat seminal vesicle by using functional studies. The reverse transcription combined with polymerase chain reaction (RT-PCR) was also used to identify of alpha1-adrenoceptor mRNA subtypes. The rank order of potency of alpha1-adrenoceptor antagonists in blocking the contractile effects of adrenaline was: prazosin = WB 4101 >>> BMY 7378 > chloroethylclonidine, indicating the presence of alpha1A-adrenoceptors in the rat seminal vesicle. In the presence of nifedipine, there was a 76% reduction in the adrenaline-induced contractions. The nifedipine-insensitive component (24%) of the contractile response to adrenaline was unaffected by chloroethylclonidine. A small pool of spare alpha1-adrenoceptors for adrenaline (0.10%) was also detected. All three alpha1-adrenoceptor subtypes were amplified when RT-PCR was performed on total RNA isolated from rat seminal vesicle. In conclusion, these data indicate the presence of three alpha1-adrenoceptor mRNA subtypes, but only alpha1A-adrenoceptors are involved in the rat seminal vesicle contraction.
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Affiliation(s)
- M A Silva
- Department of Pharmacology, Universidade Federal de São Paulo-Escola Paulista de Medicina, SP, Brazil
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26
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Pupo AS, Cavenaghi DL, Campos M, Lucena Morais P, Jurkiewicz NH, Jurkiewicz A. Effects of indoramin in rat vas deferens and aorta: concomitant alpha1-adrenoceptor and neuronal uptake blockade. Br J Pharmacol 1999; 127:1832-6. [PMID: 10482913 PMCID: PMC1566180 DOI: 10.1038/sj.bjp.0702735] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1. The actions of the alpha1-adrenoceptor antagonist indoramin have been examined against the contractions induced by noradrenaline in the rat vas deferens and aorta taking into account a putative neuronal uptake blocking activity of this antagonist which could result in self-cancelling actions. 2. Indoramin behaved as a simple competitive antagonist of the contractions induced by noradrenaline in the vas deferens and aorta yielding pA2 values of 7.38+/-0.05 (slope=0.98+/-0.03) and 6.78+/-0.14 (slope=1.08+/-0.06), respectively. 3. When the experiments were repeated in the presence of cocaine (6 microM) the potency (pA2) of indoramin in antagonizing the contractions of the vas deferens to noradrenaline was increased to 8.72+/-0.07 (slope=1.10+/-0.05) while its potency remained unchanged in the aorta (pA2=6.69+/-0.12; slope=1.04+/-0.05). 4. In denervated vas deferens, indoramin antagonized the contractions to noradrenaline with a potency similar to that found in the presence of cocaine (8.79+/-0.07; slope=1.09+/-0.06). 5. It is suggested that indoramin blocks alpha1-adrenoceptors and neuronal uptake in rat vas deferens resulting in Schild plots with slopes not different from unity even in the absence of selective inhibition of neuronal uptake. As a major consequence of this double mechanism of action, the pA2 values for this antagonist are underestimated when calculated in situations where the neuronal uptake is active, yielding spurious pKB values.
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Affiliation(s)
- A S Pupo
- Department of Pharmacology, Instituto de Biociências, UNESP, CEP 18600-000, Botucatu, Brazil
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27
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Campos MG, Oropeza MV, Lemus AE, Garcia GA, Reynoso ME, Campos P, Ponce-Monter H. The androgenic effect of norethisterone and 5alpha-norethisterone on the contractile response of the rat vas deferens to methoxamine and serotonin. Life Sci 1999; 64:PL227-33. [PMID: 10350363 DOI: 10.1016/s0024-3205(99)00132-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Norethisterone (NET) and its metabolite 5alpha-norethisterone (5alpha-NET) are competitors for the androgen receptor. The sensitivity of the rat vas deferens to the contractile action of methoxamine and serotonin is regulated by hormonal and anatomical factors. The aim of this study was to evaluate the ability of NET and 5alpha-NET to induce the androgen-regulated contractile response to methoxamine and serotonin in the epididymal and prostatic portions of rat vas deferens. Adult male rats either intact, castrated or steroid-treated castrated were used. The contractility was recorded isometrically, and non-cumulative concentration-response curves to either methoxamine or serotonin were obtained. NET and 5alpha-NET partially restored the sensitivity to methoxamine and serotonin in the epididymal portion of castrated rats. The maximal responses to both agonists were significantly higher than those observed in castrated rats, and significantly lower than the responses observed in either intact or androgen-treated castrated rats. The prostatic portion was less responsive to both agonists than the epididymal portion, in all groups but castrated rats, as castration induced sensitivity to both agonists. NET and 5alpha-NET displayed a partial though similar androgenic activity in the rat vas deferens. These results contrast with previous reports where a decrease of androgenic effect due to the 5alpha-reduction of NET has been found.
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Affiliation(s)
- M G Campos
- UIM Farmacologia, Hospital de Especialidades, Centro Medico Nacional Siglo XXI, IMSS, Mexico, DF, Mexico
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