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Adefegha SA, Oboh G, Adedipe AO. Aqueous extract of
Massularia acuminata
exerts erectogenic effect by modulating critical enzymes and hormones in streptozotocin‐induced erectile dysfunction in rats. Andrologia 2022; 54:e14629. [DOI: 10.1111/and.14629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 09/29/2022] [Accepted: 10/24/2022] [Indexed: 11/11/2022] Open
Affiliation(s)
- Stephen Adeniyi Adefegha
- Functional Foods, Nutraceuticals and Phytomedicine Laboratory, Department of Biochemistry Federal University of Technology, Akure (FUTA) Akure Nigeria
| | - Ganiyu Oboh
- Functional Foods, Nutraceuticals and Phytomedicine Laboratory, Department of Biochemistry Federal University of Technology, Akure (FUTA) Akure Nigeria
| | - Abraham Olanrewaju Adedipe
- Functional Foods, Nutraceuticals and Phytomedicine Laboratory, Department of Biochemistry Federal University of Technology, Akure (FUTA) Akure Nigeria
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2
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Olabiyi AA, Ajayi K. Diet, herbs and erectile function: A good friendship! Andrologia 2022; 54:e14424. [PMID: 35319120 DOI: 10.1111/and.14424] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 02/15/2022] [Accepted: 03/10/2022] [Indexed: 11/30/2022] Open
Abstract
Plants and plant materials have been used for thousands of years to treat and control erectile dysfunction in men. This practice has spanned many cultures and traditions around the world, with the therapeutic effects of many plants attributed to their phytochemical constituents. This review explains how polyphenols (including phenolic acids, flavonoids, terpenoids, carotenoids, alkaloids and polyunsaturated fatty acids) in plants and plant food products interact with key enzymes (phosphodiesterase-5 [PDE-5], angiotensin-converting enzyme [ACE], acetylcholinesterase [AChE], adenosine deaminase [ADA] and arginase) associated with erectile dysfunction. By modulating or altering the activity of these physiologically important enzymes, various bioactive compounds from plants or plant products can synergistically or additively provide tremendous protection against male erectile problems.
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Affiliation(s)
- Ayodeji A Olabiyi
- Department of Medical Biochemistry, Afe Babalola University Ado-Ekiti, Ado-Ekiti, Nigeria
| | - Kayode Ajayi
- Department of Nutrition and Dietetics, Afe Babalola University Ado-Ekiti, Ado-Ekiti, Nigeria
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Strath LJ, Sorge RE. Racial Differences in Pain, Nutrition, and Oxidative Stress. Pain Ther 2022; 11:37-56. [PMID: 35106711 PMCID: PMC8861224 DOI: 10.1007/s40122-022-00359-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 01/21/2022] [Indexed: 12/12/2022] Open
Abstract
Investigating the disproportionate rates of chronic pain and their related comorbidities between Black and non-Hispanic White (White) individuals is a growing area of interest, both in the healthcare community and in general society. Researchers have identified racial differences in chronic pain prevalence and severity, but still very little is known about the mechanisms underlying them. Current explanations for these differences have primarily focused on socioeconomic status and unequal healthcare between races as causal factors. Whereas these factors are informative, a racial gap still exists between Black and White individuals when these factors are controlled for. One potential cause of this racial gap in chronic pain is the differences in nutrition and dietary intake between groups. Certain foods play a key role in the inflammatory and oxidative stress pathways in the human body and could potentially influence the severity of the pain experience. Here, we review the previous literature on the surrounding topics and propose a potential mechanism to explain racial differences in the chronic pain population, based on established racial differences in diet and oxidative stress.
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Affiliation(s)
- Larissa J Strath
- Department of Psychology, The University of Alabama at Birmingham, 1300 University Blvd, Birmingham, AL, 35294, USA
| | - Robert E Sorge
- Department of Psychology, The University of Alabama at Birmingham, 1300 University Blvd, Birmingham, AL, 35294, USA.
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Batra R, Jain V, Sharma P. Adenosine: a partially discovered medicinal agent. FUTURE JOURNAL OF PHARMACEUTICAL SCIENCES 2021; 7:214. [PMID: 34697594 PMCID: PMC8529566 DOI: 10.1186/s43094-021-00353-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 09/29/2021] [Indexed: 11/18/2022] Open
Abstract
Background A plethora of chemicals exists in human body which can alter physiology in one way or other. Scientists have always been astounded by such abilities of chemicals but as the technology advances, even the chemical which was once expected to be well known changes its status to not really well known. Adenosine is one of the chemicals which is in consonance with the aforementioned statements, although previous articles have covered vast information on role of adenosine in cardiovascular physiology, bacterial pathophysiology and inflammatory diseases. In this review we have discussed adenosine and its congeners as potential promising agents in the treatment of Huntington’s disease, post-traumatic stress disorder, erectile dysfunction, viral infections (SARS-CoV) and anxiety. Main text Adenosine is a unique metabolite of ATP; which serves in signalling as well. It is made up of adenine (a nitrogenous base) and ribo-furanose (pentose) sugar linked by β-N9-glycosidic bond. Adenosine on two successive phosphorylation forms ATP (Adenosine Triphosphate) which is involved in several active processes of cell. It is also one of the building blocks (nucleotides) involved in DNA (Deoxy-ribonucleic Acid) and RNA (Ribonucleic Acid) synthesis. It is also a component of an enzyme called S-adenosyl-L-methionine (SAM) and cyano-cobalamin (vitamin B-12). Adenosine acts by binding to G protein-coupled receptor (GPCR: A1, A2A, A2B and A3) carries out various responses some of which are anti-platelet function, hyperaemic response, bone remodelling, involvement in penile erection and suppression of inflammation. On the other hand, certain microorganisms belonging to genus Candida, Staphylococcus and Bacillus utilize adenosine in order to escape host immune response (phagocytic clearance). These microbes evade host immune response by synthesizing and releasing adenosine (with the help of an enzyme: adenosine synthase-A), at the site of infection. Conclusion With the recent advancement in attribution of adenosine in physiology and pathological states, adenosine and its congeners are being looked forward to bringing a revolution in treatment of inflammation, viral infections, psychiatric and neurodegenerative disorders.
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Affiliation(s)
- Rohit Batra
- Department of Pharmacology, ShriRam College Pharmacy, Banmore, Morena, M.P 476444 India
| | - Vinay Jain
- Department of Pharmacognosy, ShriRam College Pharmacy, Banmore, Morena, M.P 476444 India
| | - Pankaj Sharma
- Department of Pharmaceutics, ShriRam College Pharmacy, Banmore, Morena, M.P 476444 India
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Campos-Martins A, Bragança B, Correia-de-Sá P, Fontes-Sousa AP. Pharmacological Tuning of Adenosine Signal Nuances Underlying Heart Failure With Preserved Ejection Fraction. Front Pharmacol 2021; 12:724320. [PMID: 34489711 PMCID: PMC8417789 DOI: 10.3389/fphar.2021.724320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Accepted: 08/04/2021] [Indexed: 12/30/2022] Open
Abstract
Heart failure with preserved ejection fraction (HFpEF) roughly represents half of the cardiac failure events in developed countries. The proposed 'systemic microvascular paradigm' has been used to explain HFpHF presentation heterogeneity. The lack of effective treatments with few evidence-based therapeutic recommendations makes HFpEF one of the greatest unmet clinical necessities worldwide. The endogenous levels of the purine nucleoside, adenosine, increase significantly following cardiovascular events. Adenosine exerts cardioprotective, neuromodulatory, and immunosuppressive effects by activating plasma membrane-bound P1 receptors that are widely expressed in the cardiovascular system. Its proven benefits have been demonstrated in preclinical animal tests. Here, we provide a comprehensive and up-to-date critical review about the main therapeutic advantages of tuning adenosine signalling pathways in HFpEF, without discounting their side effects and how these can be seized.
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Affiliation(s)
- Alexandrina Campos-Martins
- Laboratório de Farmacologia e Neurobiologia, Centro de Investigação Farmacológica e Inovação Medicamentosa (MedInUP), Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto (ICBAS-UP), Porto, Portugal
| | - Bruno Bragança
- Laboratório de Farmacologia e Neurobiologia, Centro de Investigação Farmacológica e Inovação Medicamentosa (MedInUP), Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto (ICBAS-UP), Porto, Portugal.,Department of Cardiology, Centro Hospitalar Tâmega e Sousa, Penafiel, Portugal
| | - Paulo Correia-de-Sá
- Laboratório de Farmacologia e Neurobiologia, Centro de Investigação Farmacológica e Inovação Medicamentosa (MedInUP), Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto (ICBAS-UP), Porto, Portugal
| | - Ana Patrícia Fontes-Sousa
- Laboratório de Farmacologia e Neurobiologia, Centro de Investigação Farmacológica e Inovação Medicamentosa (MedInUP), Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto (ICBAS-UP), Porto, Portugal
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Olabiyi AA, Afolabi BA, Reichert KP, Palma TV, Morsch VM, Oboh G, Schetinger MRC. Assessment of sexual behavior and neuromodulation of Cyperus esculentus L. and Tetracarpidium conophorum Müll. Arg dietary supplementation regulating the purinergic system in the cerebral cortex of L-NAME-challenged rats. J Food Biochem 2021; 45:e13862. [PMID: 34245033 DOI: 10.1111/jfbc.13862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 06/13/2021] [Accepted: 06/26/2021] [Indexed: 11/29/2022]
Abstract
This study examined the behavioral responses, purinergic receptor densities, ectonucleotidases (E-NTPDase), adenosine deaminase (ADA) activity, and nitric oxide (NO) levels along with the parameters of oxidative stress-related to erectile function in the cerebral cortex (CC) of L-NAME-challenged rats pretreated with tigernut (TN) and walnut (WN) dietary supplementation. Wistar rats (male) of 70 total animals (250-300 g) were used in this research and hence separated into seven groups (n = 10): Group I: normal control-fed basal diet; Group II: positive control-fed basal diet/L-NAME/Sildenafil citrate (5 mg kg-1 day-1 ); Group III: ED-induced (placed on a basal diet/L-NAME); Group IV: diet supplemented with processed TN (20%)/L-NAME; Group V: diet supplemented with raw TN (20%)/L-NAME; Group VI: diet supplemented with processed WN (20%)/L-NAME; and Group VII placed on a diet supplemented with raw WN (20%)/L-NAME. The rats were pretreated for 2 weeks before the L-NAME (40 mg kg-1 day-1 ) challenge on their respective diet. L-NAME brought about a decrease in the sexual behaviors evaluated while the effect was significantly reversed by supplemented diets containing TN and WN. L-NAME increased the levels of reactive oxygen species and malondialdehyde, E-NTPDase as well as ADA activities, and caused the level of NO in the CC as well as the purinoreceptor densities to be downregulated. Treatments with enriched diets, however, greatly reverse these effects. The behavioral responses and neuromodulatory capacity of the nuts displayed on the CC can, therefore, further support their aphrodisiac property. PRACTICAL APPLICATIONS: The results revealed the ability of tigernut (TN; Cyperus esculentus L.) and walnut (WN; Tetracarpidium conophorum Müll. Arg.) to enhance behavioral responses; modulate purinergic receptor densities, E-NTPDase, and ADA activities; increase NO levels; and prevent oxidative stress related to erectile function in the CC of L-NAME-challenged Wistar rats. The results show that these nuts are useful feeds for both animal and human nutrition.
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Affiliation(s)
- Ayodeji Augustine Olabiyi
- Department of Medical Biochemistry, Afe Babalola University, Ado-Ekiti, Nigeria
- Functional Foods and Nutraceuticals Unit, Department of Biochemistry, Federal University of Technology Akure, Akure, Nigeria
- Programa de Pós Graduação em Ciências Biológicas, Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Blessing Ariyo Afolabi
- Programa de Pós Graduação em Ciências Biológicas, Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Karine Paula Reichert
- Programa de Pós Graduação em Ciências Biológicas, Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Tais Vidal Palma
- Programa de Pós Graduação em Ciências Biológicas, Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Vera Maria Morsch
- Programa de Pós Graduação em Ciências Biológicas, Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Ganiyu Oboh
- Functional Foods and Nutraceuticals Unit, Department of Biochemistry, Federal University of Technology Akure, Akure, Nigeria
| | - Maria Rosa Chitolina Schetinger
- Programa de Pós Graduação em Ciências Biológicas, Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil
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Olabiyi AA, Oboh G, Ishola AO, Adeniyi PA, Boligon AA. Tetracarpidium conophorum Müll. Arg modulates sexual behaviour and biochemical parameters relevant to sexual function in male Wistar rats. ACTA ACUST UNITED AC 2018; 26:61-68. [PMID: 30391101 DOI: 10.1016/j.pathophys.2018.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 10/08/2018] [Accepted: 10/16/2018] [Indexed: 01/23/2023]
Abstract
Walnut (Tetracarpidium conophorum Müll. Arg) has been reported to be an essential ingredient in folklore medicine for sexual enhancement with little scientific validation. Hence, this study investigated the effects of walnut supplemented diet on sexual behaviour and biochemical parameters relevant to erection in male Wistar rats. Forty animals used in this study were divided into five groups (n = 8); Group 1 - normal control rats fed with basal diet, Group II - rats fed diet supplemented with 10% processed walnut, Group III - rats fed diet supplemented with 10% raw walnut, Group IV - rats fed diet supplemented with 20% processed walnut and Group V - rats fed diet supplemented with 20% raw walnut. Behavioural studies (copulation tendency and anxiety) associated with sexual function, measurement of nitric oxide (NO) levels, adenosine deaminase (ADA), arginase and acetylcholinesterase (AChE) activities in the Corpus cavernosum as well as characterization of bioactive components of the nut were evaluated. Marked reductions in ADA and arginase activities and a concomitant increase (% inclusion dependent) in the level of NO as well as enhanced sexual behaviours were observed in rat fed supplemented walnut when compared to the control. Furthermore, analysis of the walnut using high performance liquid chromatography indicated the presence of some polyphenols. From our findings, it showed that walnut improves sexual behaviour and modulates activities of key enzymes relevant to erection in male rats which may justify its used in traditional medicine.
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Affiliation(s)
- Ayodeji Augustine Olabiyi
- Functional Food and Nutraceutical Unit, Biochemistry Department, Federal University of Technology, Private Mail Bag 704, Akure, 340001, Nigeria; Medical Biochemistry Department, Afe Babalola University, Ado Ekiti, Private Mail Bag 5454, Nigeria
| | - Ganiyu Oboh
- Functional Food and Nutraceutical Unit, Biochemistry Department, Federal University of Technology, Private Mail Bag 704, Akure, 340001, Nigeria.
| | - Azeez Olakunle Ishola
- Cell Biology and Neurotoxicity Unit, Department of Anatomy, Afe Babalola University, Ado-Ekiti, Nigeria
| | - Philip Adeyemi Adeniyi
- Cell Biology and Neurotoxicity Unit, Department of Anatomy, Afe Babalola University, Ado-Ekiti, Nigeria
| | - Aline Augusti Boligon
- Phytochemical Research Laboratory, Department of Industrial Pharmacy, Federal University of Santa Maria, Build 26, Room 1115, Santa Maria, CEP 97105-900, Brazil
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Kutlu O, Karaguzel E, Okatan AE, Mentese A, Yulug E, Kazaz IO, Kutlu S, Dil E, Eren H, Alver A. Dipyridamole reduces penile apoptosis in a rat model of post-prostatectomy erectile dysfunction. Int Braz J Urol 2017; 43:966-973. [PMID: 28727374 PMCID: PMC5678531 DOI: 10.1590/s1677-5538.ibju.2017.0023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 03/23/2017] [Indexed: 12/14/2022] Open
Abstract
Purpose: Despite the nerve-sparing technique, many patients suffer from erectile dysfunction after radical prostatectomy (RP) due to cavernous nerve injury. The aim of this study was to evaluate dipyridamole as a potential treatment agent of post-radical prostatectomy erectile dysfunction. Material and methods: A total of 18 male Sprague-Dawley rats were randomized into three experimental Groups (SHAM+DMSO, BCNI+DMSO and BCNI+DIP). An animal model of bilateral cavernous nerve crush injury (BCNI) was established to mimic the partial nerve damage during nerve-sparing RP. After creating of BCNI, dimethyl sulphoxide (DMSO) was administered transperitoneally as a vehicle to SHAM+DMSO and BCNI+DMSO Groups. BCNI+DIP Group received dipyiridamole (10mg/kg/day) as a solution in DMSO for 15 days. Afterwards, rats were evaluated for in vivo erectile response to cavernous nerve stimulation. Penile tissues were also analyzed biochemically for transforming growth factor-β1 (TGF-β1) level. Penile corporal apoptosis was determined by TUNEL method. Results: Erectile response was decreased in rats with BCNI and there was no significant improvement with dipyridamole treatment. TGF-β1 levels were increased in rats with BCNI and decreased with dipyridamole treatment. Dipyridamole led to reduced penile apoptosis in rats with BCNI and there was no significant difference when compared to sham operated rats. Conclusions: Although fifteen-day dipyridamole treatment has failed to improve erectile function in rats with BCNI, the decline in both TGF-β1 levels and apoptotic indices with treatment may be helpful in protecting penile morphology after cavernous nerve injury.
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Affiliation(s)
- Omer Kutlu
- Department of Urology, School of Medicine, Akdeniz University, Antalya, Turkey.,Department of Urology School of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Ersagun Karaguzel
- Department of Urology School of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Ali Ertan Okatan
- Department of Urology School of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Ahmet Mentese
- Program of Medical Laboratory Techniques, Vocational School of Health Sciences. Karadeniz Technical University, Trabzon, Turkey
| | - Esin Yulug
- Department of Histology and Embryology, School of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Ilke Onur Kazaz
- Department of Urology School of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Selcuk Kutlu
- Department of Urology, Aydin State Hospital, Aydin, Turkey
| | - Eyup Dil
- Department of Urology School of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Huseyin Eren
- Department of Urology School of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Ahmet Alver
- Department of Biochemistry, School of Medicine, Karadeniz Technical University, Trabzon, Turkey
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Tang Y, Yuan F, Cai B, Xia W, Wang Y, Yang GY. Effect of ischaemic brain injury on sexual function in adult mice. Stroke Vasc Neurol 2017; 1:127-132. [PMID: 28959474 PMCID: PMC5435199 DOI: 10.1136/svn-2016-000013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 06/30/2016] [Accepted: 07/04/2016] [Indexed: 01/09/2023] Open
Abstract
Objective Priapism refers to a condition with persistent abnormal erection of the penis, which is usually caused by disease or injury in the brain or spinal cord, or obstruction to the outflow of blood through the dorsal vein at the root of the penis, without sexual desires. The effect of cerebral ischaemia on sexual function is unknown. The aim of this study is to explore whether priapism occurs in adult mice. Furthermore, we examined the relationship between priapism and the region of infarct in the brain. Design Adult male CD-1 mice who underwent permanent middle cerebral artery occlusion (pMCAO) were closely examined from 2 hours to 14 days postoperation. Results We found that priapism occurs in ∼80% of the mice with pMCAO, which could persist up to 14 days. Further study has demonstrated that the occurrence of priapism is related to the infarct region: priapism is found only in mice with ischaemic injury extending to the hypothalamus and the hippocampus regions. Conclusion Our result suggested priapism may be used as a deep brain injury marker for evaluating brain injury in mice after pMCAO.
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Affiliation(s)
- Yaohui Tang
- Neuroscience and Neuroengineering Center, Med-X Research Institute Shanghai Jiao Tong University, Shanghai, China
| | - Falei Yuan
- Neuroscience and Neuroengineering Center, Med-X Research Institute Shanghai Jiao Tong University, Shanghai, China
| | - Beibei Cai
- Neuroscience and Neuroengineering Center, Med-X Research Institute Shanghai Jiao Tong University, Shanghai, China
| | - Weiliang Xia
- Neuroscience and Neuroengineering Center, Med-X Research Institute Shanghai Jiao Tong University, Shanghai, China
| | - Yongting Wang
- Neuroscience and Neuroengineering Center, Med-X Research Institute Shanghai Jiao Tong University, Shanghai, China
| | - Guo-Yuan Yang
- Neuroscience and Neuroengineering Center, Med-X Research Institute Shanghai Jiao Tong University, Shanghai, China.,Shanghai Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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Xuan XJ, Bai G, Zhang CX, Xu C, Lu FD, Peng Y, Ma G, Han CH, Chen J. The application of color Doppler flow imaging in the diagnosis and therapeutic effect evaluation of erectile dysfunction. Asian J Androl 2016; 18:118-22. [PMID: 25994651 PMCID: PMC4736339 DOI: 10.4103/1008-682x.155533] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
We aim to investigate the correlations between hemodynamic parameters, penile rigidity grading, and the therapeutic effects of phosphodiesterase type 5 inhibitors using color Doppler flow imaging after intracavernosal injection in patients with erectile dysfunction. This study involved 164 patients. After intracavernosal injection with a mixture of papaverine (60 mg), prostaglandin E 1 (10 mg), and lidocaine (2%, 0.5-1 ml), the penile vessels were assessed using color Doppler flow imaging. Penile rigidity was classified based on the Erection Hardness Score system as Grades 4, 3, 2 or 1 (corresponding to Schramek Grades V to II). Then, the patients were given oral sildenafil (50-100 mg) and scored according to the International Index of Erectile Function (IIEF-5) questionnaire. The number of patients with penile rigidities of Schramek Grades II to V was 14, 18, 21, and 111, respectively. The IIEF-5 score was positively correlated with the refilling index of the penile cavernosal artery (r = 0.79, P< 0.05), the peak systolic velocity (r = 0.45, P< 0.05), and penile rigidity (r = 0.75, P< 0.05), and was negatively correlated with the end diastolic velocity (r = -0.74, P< 0.05). For patients with erectile dysfunction, both the IIEF-5 score after sildenafil administration, which is correlated with penile rigidity, and the hemodynamic parameters detected using color Doppler flow imaging may predict the effects of phosphodiesterase type 5 inhibitor treatment and could provide a reasonable model for the targeted-treatment of erectile dysfunction.
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Affiliation(s)
| | | | | | | | | | | | | | - Cong-Hui Han
- Department of Urology, The Affiliated School of Clinical Medicine, Xuzhou Medical College, Xuzhou, China
| | - Jun Chen
- Department of Infertility and Sexual Medicine, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, China
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Labazi H, Tilley SL, Ledent C, Mustafa SJ. Role of Adenosine Receptor(s) in the Control of Vascular Tone in the Mouse Pudendal Artery. J Pharmacol Exp Ther 2015; 356:673-80. [PMID: 26718241 DOI: 10.1124/jpet.115.230144] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 12/23/2015] [Indexed: 12/21/2022] Open
Abstract
Activation of adenosine receptors (ARs) has been implicated in the modulation of renal and cardiovascular systems, as well as erectile functions. Recent studies suggest that adenosine-mediated regulation of erectile function is mainly mediated through A2BAR activation. However, no studies have been conducted to determine the contribution of AR subtype in the regulation of the vascular tone of the pudendal artery (PA), the major artery supplying and controlling blood flow to the penis. Our aim was to characterize the contribution of AR subtypes and identify signaling mechanisms involved in adenosine-mediated vascular tone regulation in the PA. We used a DMT wire myograph for muscle tension measurements in isolated PAs from wild-type, A2AAR knockout, A2BAR knockout, and A2A/A2BAR double-knockout mice. Real-time reverse transcription-polymerase chain reaction was used to determine the expression of the AR subtypes. Data from our pharmacologic and genetic approaches suggest that AR activation-mediated vasodilation in the PA is mediated by both the A2AAR and A2BAR, whereas neither the A1AR nor A3AR play a role in vascular tone regulation of the PA. In addition, we showed that A2AAR- and A2BAR-mediated vasorelaxation requires activation of nitric oxide and potassium channels; however, only the A2AAR-mediated response requires protein kinase A activation. Our data are complemented by mRNA expression showing the expression of all AR subtypes with the exception of the A3AR. AR signaling in the PA may play an important role in mediating erection and represent a promising therapeutic option for the treatment of erectile dysfunction.
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Affiliation(s)
- Hicham Labazi
- Department of Physiology and Pharmacology, Center for Cardiovascular and Respiratory Sciences and Clinical Translational Science Institute, West Virginia University, Morgantown, West Virginia (H.L., S.J.M.); Department of Medicine, University of North Carolina, Chapel Hill, North Carolina (S.L.T.); and Université Libre de Bruxelles, Brussels, Belgium (C.L.)
| | - Stephen L Tilley
- Department of Physiology and Pharmacology, Center for Cardiovascular and Respiratory Sciences and Clinical Translational Science Institute, West Virginia University, Morgantown, West Virginia (H.L., S.J.M.); Department of Medicine, University of North Carolina, Chapel Hill, North Carolina (S.L.T.); and Université Libre de Bruxelles, Brussels, Belgium (C.L.)
| | - Catherine Ledent
- Department of Physiology and Pharmacology, Center for Cardiovascular and Respiratory Sciences and Clinical Translational Science Institute, West Virginia University, Morgantown, West Virginia (H.L., S.J.M.); Department of Medicine, University of North Carolina, Chapel Hill, North Carolina (S.L.T.); and Université Libre de Bruxelles, Brussels, Belgium (C.L.)
| | - S Jamal Mustafa
- Department of Physiology and Pharmacology, Center for Cardiovascular and Respiratory Sciences and Clinical Translational Science Institute, West Virginia University, Morgantown, West Virginia (H.L., S.J.M.); Department of Medicine, University of North Carolina, Chapel Hill, North Carolina (S.L.T.); and Université Libre de Bruxelles, Brussels, Belgium (C.L.)
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13
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Novel agonist of adenosine receptor induces relaxation of corpus cavernosum in guinea pigs: an in vitro and in vivo study. Urology 2015; 85:1214.e17-1214.e21. [PMID: 25917739 DOI: 10.1016/j.urology.2015.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 01/21/2015] [Accepted: 02/07/2015] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To test the relaxation effect of a new adenosine receptor agonist N-acylhydrazone derivative, 3,4-dimethoxyphenyl-N-methyl-benzoylhydrazide (LASSBio-1359), on in vitro and in vivo preparation of corpus cavernosum (CC), and its interaction with type-5 phosphodiesterase enzyme inhibitor, sildenafil. METHODS For in vitro study, an increasing concentration of LASSBio-1359 was added in the solution at the plateau isometric tension recording of isolated guinea pig CC induced by phenylephrine (30 μM). Concentration-response curve was repeated in the presence of A2A receptor antagonist, ZM 241385 (10 μM). Sildenafil-induced CC relaxing effect was compared with that of LASSBio-1359. Isobolographic analysis was performed to identify possible synergistic interaction between LASSBio-1359 and sildenafil. For in vivo study, blood pressure response in the CC of guinea pig was measured after administration of LASSBio-1359 (10 mg/kg intravenously) or sildenafil (10 mg/kg intravenously). RESULTS LASSBio-1359 caused relaxation of phenylephrine-induced contraction of isolated CC in a concentration-dependent manner (IC50 = 10.1 ± 1.8 μM), which was shifted to the right in the presence of ZM 241385 (IC50 = 27.1 ± 1.4 μM; P <.05). Isobolographic analysis showed synergistic interaction between LASSBio-1359 and sildenafil. As sildenafil, LASSBio-1359 increased blood pressure oscillation in the CC confirming its systemic efficacy. CONCLUSION CC relaxing effects induced by the adenosine A2A receptor agonist, LASSBio-1359, demonstrated in vitro and in vivo experimental protocols, represent a promise therapeutic option for the treatment of erectile dysfunction. Synergistic interaction of LASSBio-1359 with sildenafil suggests a combined use to reach a higher population of patients with erectile dysfunction.
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Anele UA, Burnett AL. Nitrergic Mechanisms for Management of Recurrent Priapism. Sex Med Rev 2015; 3:160-168. [PMID: 26478814 DOI: 10.1002/smrj.56] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
INTRODUCTION Priapism is a condition involving prolonged penile erection unrelated to sexual interest or desire. The ischemic type, including its recurrent variant, is often associated with both physical and psychological complications. As such, management is of critical importance. Ideal therapies for recurrent priapism should address its underlying pathophysiology. AIM To review the available literature on priapism management approaches particularly related to nitrergic mechanisms. METHODS A literature review of the pathophysiology and management of priapism was performed using PubMed. MAIN OUTCOME MEASURE Publications pertaining to mechanisms of the molecular pathophysiology of priapism. RESULTS Nitrergic mechanisms are characterized as major players in the molecular pathophysiology of priapism. PDE5 inhibitors represent an available therapeutic option with demonstrated ability in attenuating these underlying nitrergic derangements. Several additional signaling pathways have been found to play a role in the molecular pathophysiology of priapism and have also been associated with these nitrergic mechanisms. CONCLUSION An increasing understanding of the molecular pathophysiology of priapism has led to the discovery of new potential targets. Several mechanism-based therapeutic approaches may become available in the future.
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Affiliation(s)
- Uzoma A Anele
- The James Buchanan Brady Urological Institute and Department of Urology, The Johns Hopkins University School of Medicine, Baltimore, MD 20817
| | - Arthur L Burnett
- The James Buchanan Brady Urological Institute and Department of Urology, The Johns Hopkins University School of Medicine, Baltimore, MD 20817
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Vignozzi L, Filippi S, Comeglio P, Cellai I, Morelli A, Rastrelli G, Maneschi E, Mannucci E, Maggi M. Metformin in vitro and in vivo increases adenosine signaling in rabbit corpora cavernosa. J Sex Med 2014; 11:1694-708. [PMID: 24844317 DOI: 10.1111/jsm.12572] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
INTRODUCTION In subjects with erectile dysfunction responding poorly to sildenafil, metformin was reported to improve erections. AIMS The aim of this study is to investigate metformin's mechanism of action on erectile function, particularly focusing on adenosine (ADO) and nitric oxide (NO) signaling in an animal model of high-fat diet (HFD)-induced metabolic syndrome. METHODS In vitro contractility studies of penile strips. Penile expression of genes related to ADO or NO signaling was also evaluated. MAIN OUTCOME MEASURE In vitro contractility studies were used to investigate the effect of in vivo and ex vivo metformin administration on ADO- or acetylcholine (Ach)-induced relaxation of penile strips from HFD as compared with animals fed a regular diet (RD). RESULTS Expression of ADO receptor type 3 (A3 R), ADO deaminase (ADA), AMP deaminase type 1 (AMPD1), and 2 (AMPD2) was decreased in HFD as compared with RD. Accordingly, in HFD the ADO relaxant effect was potentiated as compared with RD (P < 0.02). In vivo metformin treatment in both RD and HFD significantly increased the ADO relaxing effect (P < 0.0001 and P < 0.01, respectively, vs. relative untreated groups) although to a different extent. In fact, the half-maximal inhibitory concentration (IC50 )/IC50 ratio in RD increased fourfold vs. HFD (RD IC50 ratio = 13.75 ± 2.96; HFD IC50 ratio = 2.85 ± 0.52). In corpora cavernosa (CC) from HFD, in vivo metformin (i) normalized A3 R, ADA, and AMPD1; (ii) further decreased AMPD2; (iii) increased dimethylarginine dimethylamino-hydrolase; and (iv) partially restored impaired Ach-induced relaxation. Ex vivo metformin time and dose dependently increased the relaxant effect of ADO in RD. The potentiating effect of metformin on ADO-induced relaxation was significantly reduced by preincubation with NO synthase inhibitor N(ω) -Nitro-L-arginine methyl ester hydrochloride (L-NAME). Interestingly, in vivo testosterone supplementation in HFD rabbits (i) increased penile expression of endothelial NO synthase and AMPD2 and (ii) restored metformin's potentiating effect on ADO-induced relaxation up to RD level. CONCLUSION Metformin in vivo and ex vivo increases ADO signaling in CC, most probably interfering with NO formation and ADO breakdown.
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Affiliation(s)
- Linda Vignozzi
- Sexual Medicine and Andrology Unit, Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy
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Burnstock G. Purinergic signalling in the reproductive system in health and disease. Purinergic Signal 2014; 10:157-87. [PMID: 24271059 PMCID: PMC3944041 DOI: 10.1007/s11302-013-9399-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/24/2013] [Indexed: 12/16/2022] Open
Abstract
There are multiple roles for purinergic signalling in both male and female reproductive organs. ATP, released as a cotransmitter with noradrenaline from sympathetic nerves, contracts smooth muscle via P2X1 receptors in vas deferens, seminal vesicles, prostate and uterus, as well as in blood vessels. Male infertility occurs in P2X1 receptor knockout mice. Both short- and long-term trophic purinergic signalling occurs in reproductive organs. Purinergic signalling is involved in hormone secretion, penile erection, sperm motility and capacitation, and mucous production. Changes in purinoceptor expression occur in pathophysiological conditions, including pre-eclampsia, cancer and pain.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK,
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Karakeci A, Firdolas F, Ozan T, Unus I, Ogras MS, Orhan I. Second pathways in the pathophysiology of ischemic priapism and treatment alternatives. Urology 2013; 82:625-9. [PMID: 23987157 DOI: 10.1016/j.urology.2013.06.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 05/28/2013] [Accepted: 06/19/2013] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To evaluate the early therapeutic alternatives such as bosentan, an endothelin receptor blocker, theophylline, an adenosin receptor blocker, and a nonselective phosphodiesterase enzyme inhibitor, zinc protoporphyrin (ZnPP), a heme oxygenase 1 inhibitor, for the therapy of ischemic priapism in the rat models. METHODS Twenty-four Sprague-Dawley rats were randomly divided into 4 equal groups: control group, ZnPP group, bosentan group, and theophylline group. Erection was provided by vacuum constriction method and maintained for 4 hours for achieving the priapism in all groups. The rats in the control group were administered 1 mL/kg saline intraperitoneally (ip). The rats in group 2 were administered 25 mg/kg ZnPP ip. The rats in group 3 were administered 0.25 mg/kg bosentan ip. The rats in group 4 were administered 100 mg/kg theophylline ip. Six rats from each group were decapitated after 6 hours of drug administration. Then endothelin 1, adenosine deaminase, heme oxygenase 1 enzymatic activity, and apoptosis index in the cavernous tissues were estimated. RESULTS Cavernous tissue endothelin 1, adenosine deaminase, heme oxygenase 1 enzymatic activity levels, and apoptosis index were significantly decreased in bosentan, theophylline, and ZnPP-treated rats compared with the controls. CONCLUSION Inhibition of priapism induced apoptosis with bosentan, theophylline, and ZnPP seems promising on preserving erectile function.
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Affiliation(s)
- Ahmet Karakeci
- Department of Urology, Elazig Harput Government Hospital, Elazig, Turkey
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Decaluwé K, Pauwels B, Boydens C, Van de Voorde J. Treatment of erectile dysfunction: new targets and strategies from recent research. Pharmacol Biochem Behav 2013; 121:146-57. [PMID: 24291648 DOI: 10.1016/j.pbb.2013.11.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 11/18/2013] [Indexed: 12/15/2022]
Abstract
In recent years, research on penile erection has increasingly been centered on the molecular mechanisms involved. Major progress has been made in the field and at present a whole number of neurotransmitters, chemical effectors, growth factors, second-messenger molecules, ions, intercellular proteins, and hormones have been characterized as components of the complex process of erection. This knowledge has led to the discovery of several new therapeutic targets and multiple medical approaches for the treatment of erectile dysfunction (ED). This review focuses on the progress made in this field within the last few years.
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Affiliation(s)
- K Decaluwé
- Department of Pharmacology, Ghent University, Ghent, Belgium
| | - B Pauwels
- Department of Pharmacology, Ghent University, Ghent, Belgium
| | - C Boydens
- Department of Pharmacology, Ghent University, Ghent, Belgium
| | - J Van de Voorde
- Department of Pharmacology, Ghent University, Ghent, Belgium.
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Doyle C, Sergeant GP, Hollywood MA, McHale NG, Thornbury KD. ATP evokes inward currents in corpus cavernosum myocytes. J Sex Med 2013; 11:64-74. [PMID: 24165499 DOI: 10.1111/jsm.12364] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
INTRODUCTION Although adenosine triphosphate (ATP) has often been reported to relax the corpus cavernosum, this may be mediated by indirect effects, such as release of nitric oxide from the endothelium. Recent data suggest that P2X(1) receptors may be up-regulated in diabetes, and these exert an anti-erectile effect by causing the corpus cavernosum smooth muscle cells (CCSMCs) to contract. However, to date, there is no functional evidence that ATP can directly stimulate CCSMC. AIMS This study aims to (i) to directly examine the effect of ATP on membrane currents in freshly isolated CCSMC, where influences of endothelium and other cells are absent; and (ii) to determine the receptor subtypes, ionic currents, and Ca(2+) signals stimulated by ATP. METHODS CCSMCs were enzymatically dispersed from male New Zealand White rabbits for patch clamp recording and measurement of intracellular Ca(2+) in fluo-4-loaded cells using spinning disk confocal microscopy. MAIN OUTCOME MEASURES Patch clamp recordings were made of ATP-evoked membrane currents and spontaneous membrane currents. Spinning disk confocal imaging of intracellular Ca(2+) was performed, and the response to ATP was recorded. RESULTS ATP evoked repeatable inward currents in CCSMC (1st application: -675 ± 101 pA; 2nd application: -694 ± 120 pA, N = 9, P = 0.77). ATP-induced currents were reduced by suramin from -380 ± 121 to -124 ± 37 pA (N = 8, P < 0.05), by α,β-methylene ATP from -755 ± 235 to 139 ± 49 pA (N = 5, P < 0.05), and by NF449 from -419 ± to -51 ± 13 pA (N = 6, P < 0.05). In contrast, MRS2500, a P2Y1(1,12,13) antagonist, had no effect on ATP responses (control: -838 ± 139 pA; in MRS2500: -822 ± 184 pA, N = 13, P = 0.84) but blocked inward currents evoked by 2-MeSATP, a P2Y1,12,13 agonist (control: -623 ± 166 pA; in MRS2500: -56 ± 25 pA, N = 6, P < 0.05). The ATP-evoked inward current was unaffected by changing the transmembrane Cl(-) gradient but reversed in direction when extracellular Na(+) was reduced, indicating that it was a cation current. CONCLUSIONS ATP directly stimulates CCSMC by evoking a P2X-mediated cation current.
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Affiliation(s)
- Claire Doyle
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
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Neuzillet Y, Hupertan V, Cour F, Botto H, Lebret T. A randomized, double-blind, crossover, placebo-controlled comparative clinical trial of arginine aspartate plus adenosine monophosphate for the intermittent treatment of male erectile dysfunction. Andrology 2012; 1:223-8. [DOI: 10.1111/j.2047-2927.2012.00046.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 10/30/2012] [Accepted: 11/02/2012] [Indexed: 11/26/2022]
Affiliation(s)
| | - V. Hupertan
- Department of Urology; Hôpital Bichat; Paris; France
| | - F. Cour
- Department of Urology; Hôpital Foch; Suresnes; France
| | - H. Botto
- Department of Urology; Hôpital Foch; Suresnes; France
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Hupertan V, Neuzillet Y, Stücker O, Pons C, Leammel E, Lebret T. Effects of nucleotides adenosine monophosphate and adenosine triphosphate in combination with L-arginine on male rabbit corpus cavernosum tissue. ACTA ACUST UNITED AC 2012; 35:860-866. [PMID: 22709341 DOI: 10.1111/j.1365-2605.2012.01290.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Purines and more specifically adenosine monophosphate (AMP) and adenosine triphosphate (ATP) have a strong relaxant effect on smooth muscle cells of the dog, rabbit and human corpus cavernosum, to approximately the same degree as nitric oxide (NO). However, purines are considered as modulators of erectile function rather than key mediators. This suggests that the use of purines combined with NO donors could be effective to treat some specific erectile disorders. The relaxation induced by the combination of l-arginine (Arg), a natural substrate for NO synthase, was assessed with a purine-nucleotide (AMP, ATP) on a rabbit corpus cavernosum model, to determine if these substances could potentiate each other's effect. When a pre-contraction was induced by phenylephrine, AMP alone induced a 43% CC relaxation rate and ATP alone a 26% rate. The relaxation rate induced by Arg was lower in comparison (8% at 5.10(-4) m vs. 25% at AMP 5.10(-4) m and 15% at ATP 5.10(-4) m). NO synthase inhibitor n-nitro-l-arginine did not modify the relaxing effect provoked by AMP suggesting that the mechanism of action of this nucleotide does not involve the NO pathway. The combination of Arg at 5.10(-4) m with either AMP or ATP at different doses ranging from 5.10(-4) to 10(-3) m significantly enhanced the relaxing response reaching rates of 62 and 80% respectively, leading to a synergistic effect. The present data indicate that a 'NO donor' combined with an 'adenosine donor' could be an effective therapeutic approach.
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Affiliation(s)
- V Hupertan
- Department of Urology, Hôpital Bichat, Paris, France
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Sickling cells, cyclic nucleotides, and protein kinases: the pathophysiology of urogenital disorders in sickle cell anemia. Anemia 2012; 2012:723520. [PMID: 22745902 PMCID: PMC3382378 DOI: 10.1155/2012/723520] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 04/16/2012] [Accepted: 04/22/2012] [Indexed: 02/01/2023] Open
Abstract
Sickle cell anemia is one of the best studied inherited diseases, and despite being caused by a single point mutation in the HBB gene, multiple pleiotropic effects of the abnormal hemoglobin S production range from vaso-occlusive crisis, stroke, and pulmonary hypertension to osteonecrosis and leg ulcers. Urogenital function is not spared, and although priapism is most frequently remembered, other related clinical manifestations have been described, such as nocturia, enuresis, increased frequence of lower urinary tract infections, urinary incontinence, hypogonadism, and testicular infarction. Studies on sickle cell vaso-occlusion and priapism using both in vitro and in vivo models have shed light on the pathogenesis of some of these events. The authors review what is known about the deleterious effects of sickling on the genitourinary tract and how the role of cyclic nucleotides signaling and protein kinases may help understand the pathophysiology underlying these manifestations and develop novel therapies in the setting of urogenital disorders in sickle cell disease.
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Abstract
The erectile status of penile tissue is governed largely by the tone of cavernosal smooth muscle cells, which is determined by the balance of vascular relaxants and constrictors. Vascular relaxants play a key role in regulating the tone of cavernosal smooth muscle and thus the initiation and maintenance of penile erection. Early studies drew attention to the potential role of adenosine signaling in this process. However, the serendipitous discovery of the effect of sildenafil on erectile physiology drew more attention toward nitric oxide (NO) as a vasodilator in the process of penile erection, and a recently discovered, unexpected erectile phenotype of adenosine deaminase-deficient mice reemphasizes the importance of adenosine as a key regulatory of erectile status. Adenosine, like NO, is a potent and short-lived vasorelaxant that functions via cyclic nucleotide second messenger signaling to promote smooth muscle relaxation. Recent studies reviewed here show that adenosine functions to relax the corpus cavernosum and promote penile erection. Excess adenosine in penile tissue contributes to the disorder called priapism, and impaired adenosine signaling is associated with erectile dysfunction. More recent research summarized in this review reveals that adenosine functions as a key endogenous vasodilator in the initiation and maintenance of normal penile erection. This new insight highlights adenosine signaling pathways operating in penile tissue as significant therapeutic targets for the treatment of erectile disorders.
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Affiliation(s)
- Jiaming Wen
- Department of Biochemistry and Molecular Biology, UT Houston Medical School, Texas 77225, USA
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Bivalacqua TJ, Musicki B, Kutlu O, Burnett AL. New Insights into the Pathophysiology of Sickle Cell Disease‐Associated Priapism. J Sex Med 2012; 9:79-87. [DOI: 10.1111/j.1743-6109.2011.02288.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Andersson KE. Mechanisms of penile erection and basis for pharmacological treatment of erectile dysfunction. Pharmacol Rev 2011; 63:811-59. [PMID: 21880989 DOI: 10.1124/pr.111.004515] [Citation(s) in RCA: 228] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Erection is basically a spinal reflex that can be initiated by recruitment of penile afferents, both autonomic and somatic, and supraspinal influences from visual, olfactory, and imaginary stimuli. Several central transmitters are involved in the erectile control. Dopamine, acetylcholine, nitric oxide (NO), and peptides, such as oxytocin and adrenocorticotropin/α-melanocyte-stimulating hormone, have a facilitatory role, whereas serotonin may be either facilitatory or inhibitory, and enkephalins are inhibitory. The balance between contractant and relaxant factors controls the degree of contraction of the smooth muscle of the corpora cavernosa (CC) and determines the functional state of the penis. Noradrenaline contracts both CC and penile vessels via stimulation of α₁-adrenoceptors. Neurogenic NO is considered the most important factor for relaxation of penile vessels and CC. The role of other mediators, released from nerves or endothelium, has not been definitely established. Erectile dysfunction (ED), defined as the "inability to achieve or maintain an erection adequate for sexual satisfaction," may have multiple causes and can be classified as psychogenic, vasculogenic or organic, neurologic, and endocrinologic. Many patients with ED respond well to the pharmacological treatments that are currently available, but there are still groups of patients in whom the response is unsatisfactory. The drugs used are able to substitute, partially or completely, the malfunctioning endogenous mechanisms that control penile erection. Most drugs have a direct action on penile tissue facilitating penile smooth muscle relaxation, including oral phosphodiesterase inhibitors and intracavernosal injections of prostaglandin E₁. Irrespective of the underlying cause, these drugs are effective in the majority of cases. Drugs with a central site of action have so far not been very successful. There is a need for therapeutic alternatives. This requires identification of new therapeutic targets and design of new approaches. Research in the field is expanding, and several promising new targets for future drugs have been identified.
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Affiliation(s)
- K-E Andersson
- Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Medical Center Boulevard, Winston Salem, NC 27157, USA.
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Wen J, Dai Y, Zhang Y, Zhang W, Kellems RE, Xia Y. Impaired erectile function in CD73-deficient mice with reduced endogenous penile adenosine production. J Sex Med 2011; 8:2172-80. [PMID: 21595838 DOI: 10.1111/j.1743-6109.2011.02316.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Adenosine has been implicated in normal and abnormal penile erection. However, a direct role of endogenous adenosine in erectile physiology and pathology has not been established. AIM To determine the functional role of endogenous adenosine production in erectile function. METHODS CD73-deficient mice (CD73(-/-)) and age-matched wild-type (WT) mice were used. Some WT mice were treated with alpha, beta-methylene adenosine diphosphate (ADP) (APCP), a CD73-specific inhibitor. High-performance liquid chromatography was used to measure adenosine levels in mouse penile tissues. In vivo assessment of intracorporal pressure (ICP) normalized to mean arterial pressure (MAP) in response to electrical stimulation (ES) of the cavernous nerve was used. MAIN OUTCOME MEASUREMENT The main outcome measures of this study were the in vivo assessment of initiation and maintenance of penile erection in WT mice and mice with deficiency in CD73 (ecto-5'-nucleotidase), a key cell-surface enzyme to produce extracellular adenosine. RESULTS Endogenous adenosine levels were elevated in the erected state induced by ES of cavernous nerve compared to the flaccid state in WT mice but not in CD73(-/-) mice. At cellular levels, we identified that CD73 was highly expressed in the neuronal, endothelial cells, and vascular smooth muscle cells in mouse penis. Functionally, we found that the ratio of ES-induced ICP to MAP in CD73(-/-) mice was reduced from 0.48 ± 0.03 to 0.33 ± 0.05 and ES-induced slope was reduced from 0.30 ± 0.13 mm Hg/s to 0.15 ± 0.05 mm Hg/s (both P < 0.05). The ratio of ES-induced ICP to MAP in APCP-treated WT mice was reduced from 0.49 ± 0.03 to 0.38 ± 0.06 and ES-induced slope was reduced from 0.29 ± 0.11 mm Hg/s to 0.19 ± 0.04 mm Hg/s (both P < 0.05). CONCLUSION Overall, our findings demonstrate that CD73-dependent production of endogenous adenosine plays a direct role in initiation and maintenance of penile erection.
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Affiliation(s)
- Jiaming Wen
- Department of Biochemistry and Molecular Biology, University of Texas-Houston Medical School, Houston, TX 77030, USA
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Wen J, Jiang X, Dai Y, Zhang Y, Tang Y, Sun H, Mi T, Kellems RE, Blackburn MR, Xia Y. Adenosine deaminase enzyme therapy prevents and reverses the heightened cavernosal relaxation in priapism. J Sex Med 2011; 7:3011-22. [PMID: 19845544 DOI: 10.1111/j.1743-6109.2009.01552.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Priapism featured with painful prolonged penile erection is dangerous and commonly seen in sickle cell disease (SCD). The preventive approaches or effective treatment options for the disorder are limited because of poor understanding of its pathogenesis. Recent studies have revealed a novel role of excess adenosine in priapism caused by heightened cavernosal relaxation, and therefore present an intriguing mechanism-based therapeutic possibility. AIM The aim of this study was to determine the therapeutic effects of adenosine deaminase (ADA) enzyme therapy to lower adenosine in priapism. METHODS Both ADA-deficient mice and SCD transgenic (Tg) mice display priapism caused by excessive adenosine. Thus, we used these two distinct lines of mouse models of priapism as our investigative tools. Specifically, we treated both of these mice with different dosages of polyethylene glycol-modified ADA (PEG-ADA) to reduce adenosine levels in vivo. At the end points of the experiments, we evaluated the therapeutic effects of PEG-ADA treatment by measuring adenosine levels and monitoring the cavernosal relaxation. MAIN OUTCOME MEASURES Adenosine levels in penile tissues were measured by high-performance liquid chromatography, and cavernosal relaxation was quantified by electrical field stimulation (EFS)-induced corporal cavernosal strip (CCS) assays. RESULTS We found that lowering adenosine levels in penile tissues by PEG-ADA treatment from birth in ADA-deficient mice prevented the increased EFS-induced CCS relaxation associated with priapism. Intriguingly, in both ADA-deficient mice and SCD Tg mice with established priapism, we found that normalization of adenosine levels in penile tissues by PEG-ADA treatment relieved the heightened EFS-induced cavernosal relaxation in priapism. CONCLUSIONS Our studies have identified that PEG-ADA is a novel, safe, and mechanism-based drug to prevent and correct excess adenosine-mediated increased cavernosal relaxation seen in two independent priapic animal models, and suggested its therapeutic possibility in men suffering from priapism.
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Affiliation(s)
- Jiaming Wen
- Department of Biochemistry and Molecular Biology, University of Texas-Houston Medical School, Houston, TX 77030, USA
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Burnett AL, Goldstein I, Andersson KE, Argiolas A, Christ G, Park K, Xin ZC. Future sexual medicine physiological treatment targets. J Sex Med 2011; 7:3269-304. [PMID: 21029380 DOI: 10.1111/j.1743-6109.2010.02025.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
INTRODUCTION Sexual function in men and women incorporates physiologic processes and regulation of the central and peripheral nervous systems, the vascular system, and the endocrine system. There is need for state-of-the-art information as there is an evolving research understanding of the underlying molecular biological factors and mechanisms governing sexual physiologic functions. AIM To develop an evidence-based, state-of-the-art consensus report on the current knowledge of the major cellular and molecular targets of biologic systems responsible for sexual physiologic function. METHODS State-of-the-art knowledge representing the opinions of seven experts from four countries was developed in a consensus process over a 2-year period. MAIN OUTCOME MEASURES Expert opinion was based on the grading of evidence-based medical literature, widespread internal committee discussion, public presentation, and debate. RESULTS Scientific investigation in this field is needed to increase knowledge and foster development of the future line of treatments for all forms of biological-based sexual dysfunction. This article addresses the current knowledge of the major cellular and molecular targets of biological systems responsible for sexual physiologic function. Future treatment targets include growth factor therapy, gene therapy, stem and cell-based therapies, and regenerative medicine. CONCLUSIONS Scientific discovery is critically important for developing new and increasingly effective treatments in sexual medicine. Broad physiologic directions should be vigorously explored and considered for future management of sexual disorders.
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Affiliation(s)
- Arthur L Burnett
- The James Buchanan Brady Urological Institute, The Johns Hopkins Hospital, Baltimore, MD, USA.
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Phatarpekar PV, Wen J, Xia Y. Role of adenosine signaling in penile erection and erectile disorders. J Sex Med 2011; 7:3553-64. [PMID: 19889148 DOI: 10.1111/j.1743-6109.2009.01555.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Penile erection is a hemodynamic process, which results from increased flow and retention of blood in the penile organ due to the relaxation of smooth muscle cells. Adenosine, a physiological vasorelaxant, has been shown to be a modulator of penile erection. AIM To summarize the research on the role of adenosine signaling in normal penile erection and erectile disorders. MAIN OUTCOME MEASURES Evidence in the literature on the association between adenosine signaling and normal and abnormal penile erection, i.e., erectile dysfunction (ED) and priapism. METHODS The article reviews the literature on the role of endogenous and exogenous adenosine in normal penile erection, as well as in erectile disorders namely, ED and priapism. RESULTS Adenosine has been shown to relax corpus cavernosum from various species including human in both in vivo and in vitro studies. Neuromodulatory role of adenosine in corpus cavernosum has also been demonstrated. Impaired adenosine signaling through A(2B) receptor causes partial resistance of corpus cavernosum, from men with organic ED, to adenosine-mediated relaxation. Increased level of adenosine has been shown to be a causative factor for priapism. CONCLUSION Overall, the research reviewed here suggests a general role of exogenous and endogenous adenosine signaling in normal penile erection. From this perspective, it is not surprising that impaired adenosine signaling is associated with ED, and excessive adenosine signaling is associated with priapism. Adenosine signaling represents a potentially important diagnostic and therapeutic target for the treatment of ED and priapism.
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Affiliation(s)
- Prasad V Phatarpekar
- Department of Biochemistry and Molecular Biology, University of Texas Medical School at Houston, Houston, TX, USA
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Lau DHW, Metcalfe MJ, Mumtaz FH, Mikhailidis DP, Thompson CS. Purinergic modulation of human corpus cavernosum relaxation. ACTA ACUST UNITED AC 2009; 32:149-55. [DOI: 10.1111/j.1365-2605.2007.00828.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Dai Y, Zhang Y, Phatarpekar P, Mi T, Zhang H, Blackburn MR, Xia Y. Adenosine Signaling, Priapism and Novel Therapies. J Sex Med 2009; 6 Suppl 3:292-301. [DOI: 10.1111/j.1743-6109.2008.01187.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Mi T, Abbasi S, Zhang H, Uray K, Chunn JL, Xia LW, Molina JG, Weisbrodt NW, Kellems RE, Blackburn MR, Xia Y. Excess adenosine in murine penile erectile tissues contributes to priapism via A2B adenosine receptor signaling. J Clin Invest 2008; 118:1491-501. [PMID: 18340377 DOI: 10.1172/jci33467] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 01/23/2008] [Indexed: 11/17/2022] Open
Abstract
Priapism, abnormally prolonged penile erection in the absence of sexual excitation, is associated with ischemia-mediated erectile tissue damage and subsequent erectile dysfunction. It is common among males with sickle cell disease (SCD), and SCD transgenic mice are an accepted model of the disorder. Current strategies to manage priapism suffer from a poor fundamental understanding of the molecular mechanisms underlying the disorder. Here we report that mice lacking adenosine deaminase (ADA), an enzyme necessary for the breakdown of adenosine, displayed unexpected priapic activity. ADA enzyme therapy successfully corrected the priapic activity both in vivo and in vitro, suggesting that it was dependent on elevated adenosine levels. Further genetic and pharmacologic evidence demonstrated that A2B adenosine receptor-mediated (A2BR-mediated) cAMP and cGMP induction was required for elevated adenosine-induced prolonged penile erection. Finally, priapic activity in SCD transgenic mice was also caused by elevated adenosine levels and A2BR activation. Thus, we have shown that excessive adenosine accumulation in the penis contributes to priapism through increased A2BR signaling in both Ada -/- and SCD transgenic mice. These findings provide insight regarding the molecular basis of priapism and suggest that strategies to either reduce adenosine or block A2BR activation may prove beneficial in the treatment of this disorder.
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Affiliation(s)
- Tiejuan Mi
- Department of Biochemistry and Molecular Biology, University of Texas Medical School at Houston, Houston, Texas 77030, USA
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Kataoka K, Furukawa K, Nagao K, Ishii N, Tsuru H. The participation of adenosine receptors in the adenosine 5'-triphosphate-induced relaxation in the isolated rabbit corpus cavernosum penis. Int J Urol 2008; 14:764-8. [PMID: 17681071 DOI: 10.1111/j.1442-2042.2007.01803.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM To investigate the participation of adenosine receptors in the adenosine 5'-triphosphate (ATP)-induced relaxation in the corpus cavernosum penis (CCP) of rabbits. METHODS The ATP-induced relaxation was assessed on the noradrenaline precontracted CCP of rabbits in the presence and absence of 8-(3-chlorostyryl)caffeine (CSC); an adenosine A(2A) receptor antagonist; alloxazine and MRS1754; adenosine A(2B) receptor antagonists; and ARL67156, an inhibitor of ecto-nucleoside triphosphate diphosphohydrolases. RESULTS Adenosine and ATP relaxed the noradrenaline precontracted CCP of rabbits in a concentration-dependent manner. The adenosine- and ATP-induced relaxations were suppressed by alloxazine and MRS1754, but not by 8-(3-chlorostyryl)caffeine. ARL67156 potentiated the ATP-induced relaxation but not the adenosine-induced one. MRS1754 suppressed the ATP-induced relaxation potentiated by ARL67156. CONCLUSIONS The above results suggest that, in the CCP of rabbits, the adenosine receptor mediating adenosine-induced relaxation is of the A(2B) receptor and the ATP directly causes relaxation through the A(2B) receptor on the CCP.
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Affiliation(s)
- Kazuyoshi Kataoka
- Department of Urology, Faculty of Medicine, Toho University, Omorinishi, Tokyo, Japan
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Tostes RC, Giachini FRC, Carneiro FS, Leite R, Inscho EW, Webb RC. Determination of Adenosine Effects and Adenosine Receptors in Murine Corpus Cavernosum. J Pharmacol Exp Ther 2007; 322:678-85. [PMID: 17494861 DOI: 10.1124/jpet.107.122705] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study tested the hypothesis that adenosine, in murine corpora cavernosa, produces direct relaxation of smooth muscle cells and inhibition of contractile responses mediated by sympathetic nerve stimulation. Penes were excised from anesthetized male C57BL/6 mice, dissected, and cavernosal strips were mounted to record isometric force. Adenosine, 2-chloroadenosine (stable analog of adenosine), and 2-phenylaminoadenosine (CV1808) (A2(A)/A2(B) agonist) produced concentration-dependent relaxations of phenylephrine-contracted tissues. Relaxation to 2-chloroadenosine was inhibited, in a concentration-dependent manner, by 2-(2-furanyl)-7-(2-phenylethyl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine (SCH58261; A2(A) antagonist; 10(-9)-10(-6) M) and N-(4-acetylphenyl)-2-[4-(2,3,6,7-tetrahydro-2,6-dioxo-1,3-dipropyl-1H-purin-8-yl)phenoxy]acetamida (MRS1706; A2(B) antagonist; 10(-8)-10(-6) M). The combination of both antagonists abrogated 2-chloroadenosine-induced relaxation. Electrical field stimulation (EFS; 1-32 Hz) of adrenergic nerves produced frequency-dependent contractions that were inhibited by compounds that increase adenosine levels, such as 5'-iodotubercidin (adenosine kinase inhibitor), erythro-9-(2-hydroxy-3-nonyl)adenine (adenosine deaminase inhibitor), and dipyridamole (inhibitor of adenosine transport). The adenosine A1 receptor agonist N(6)-cyclopentyladenosine (C8031) right-shifted contractile responses to EFS, with a significant inhibitory effect at 10(-6) M. Blockade of adenosine A1 receptors with 8-cyclopentyl-1,3-dipropylxanthine (C101) (10(-7) M) enhanced contractile responses to EFS and eliminated the inhibitory effects of 5'-iodotubercidin. Dipyridamole and 5'-iodotubercidin had no effect on adenosine-mediated relaxation. In summary, adenosine directly relaxes cavernosal smooth muscle cells, by the activation of A2(A)/A2(B) receptor subtypes. In addition, adenosine negatively modulates sympathetic neurotransmission, by A1 receptor subtype activation, in murine corpora cavernosa. Adenosine may subserve dual roles in modulating the physiological mechanisms of erection in mice.
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Affiliation(s)
- Rita C Tostes
- Department of Pharmacology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
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Adachi H, Palaniappan KK, Ivanov AA, Bergman N, Gao ZG, Jacobson KA. Structure-activity relationships of 2,N(6),5'-substituted adenosine derivatives with potent activity at the A2B adenosine receptor. J Med Chem 2007; 50:1810-27. [PMID: 17378544 PMCID: PMC3405160 DOI: 10.1021/jm061278q] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
2, N6, and 5'-substituted adenosine derivatives were synthesized via alkylation of 2-oxypurine nucleosides leading to 2-arylalkylether derivatives. 2-(3-(Indolyl)ethyloxy)adenosine 17 was examined in both binding and cAMP assays and found to be a potent agonist of the human A2BAR. Simplification, altered connectivity, and mimicking of the indole ring of 17 failed to maintain A2BAR potency. Introduction of N6-ethyl or N6-guanidino substitution, shown to favor A2BAR potency, failed to enhance potency in the 2-(3-(indolyl)ethyloxy)adenosine series. Indole 5' '- or 6' '-halo substitution was favored at the A2BAR, but a 5'-N-ethylcarboxyamide did not further enhance potency. 2-(3' '-(6' '-Bromoindolyl)ethyloxy)adenosine 28 displayed an A2BAR EC50 value of 128 nM, that is, more potent than the parent 17 (299 nM) and similar to 5'-N-ethylcarboxamidoadenosine (140 nM). Compound 28 was a full agonist at A2B and A2AARs and a low efficacy partial agonist at A1 and A3ARs. Thus, we have identified and optimized 2-(2-arylethyl)oxo moieties in AR agonists that enhance A2BAR potency and selectivity.
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Affiliation(s)
- Hayamitsu Adachi
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Krishnan K. Palaniappan
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Andrei A. Ivanov
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Nathaniel Bergman
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Baraldi PG, Preti D, Tabrizi MA, Fruttarolo F, Romagnoli R, Carrion MD, Cara LCL, Moorman AR, Varani K, Borea PA. Synthesis and biological evaluation of novel 1-deoxy-1-[6-[((hetero)arylcarbonyl)hydrazino]- 9H-purin-9-yl]-N-ethyl-beta-D-ribofuranuronamide derivatives as useful templates for the development of A2B adenosine receptor agonists. J Med Chem 2007; 50:374-80. [PMID: 17228880 DOI: 10.1021/jm061170a] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The lack of molecules endowed with selective and potent agonistic activity toward the hA2B adenosine receptors has limited the studies on this pharmacological target and consequently the evaluation of its therapeutic potential. We report the design and the synthesis of the first potent (EC50 in the nanomolar range) and selective hA2B adenosine receptor agonists consisting of 1-deoxy-1-[6-[((hetero)arylcarbonyl)hydrazino]-9H-purin-9-yl]-N-ethyl-beta-D-ribofuranuronamide derivatives. The concurrent effect of 6-substitution of the purine nucleus with a ((hetero)arylcarbonyl)hydrazino function and a 2-chloro substitution has been investigated in such NECA derivatives.
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Faria M, Magalhães-Cardoso T, Lafuente-de-Carvalho JM, Correia-de-Sá P. Corpus Cavernosum from Men with Vasculogenic Impotence Is Partially Resistant to Adenosine Relaxation due to Endothelial A2B Receptor Dysfunction. J Pharmacol Exp Ther 2006; 319:405-13. [PMID: 16837560 DOI: 10.1124/jpet.106.107821] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although adenosine has been implicated in penile erection in human males, the receptor subtype responsible for adenosine regulation of human corpus cavernosum (HCC) smooth muscle tone is still a matter of debate. Using selective adenosine agonists and antagonists, we aimed at characterizing the adenosine receptors mediating relaxation of precontracted (with 1 microM phenylephrine) HCC strips. HCC specimens were collected from control subjects (organ donors) and from patients with severe vasculogenic erectile dysfunction (ED). In control subjects, adenosine and 5'-N-ethyl-carboxamide adenosine (NECA) fully relaxed HCC. The selective A(2A) receptor agonist 2-[4-(2-p-carboxy ethyl)phenylamino]-5'-N-ethylcarboxamido adenosine (CGS21680C) produced only a partial relaxation (30-50%) of HCC, which could be further enhanced by simultaneous application of 100 microM NECA. The selective A(2B) receptor antagonist N-(4-acetylphenyl)-2-[4-(2,3,6,7-tetrahydro-2,6-dioxo-1,3-dipropyl-1H-purin-8-il)phenoxy] acetamida (MRS1706) (10 nM) attenuated NECA-induced relaxation without affecting CGS21680C action. The A(2A) receptor antagonist 4-{2-[7-amino-2-(2-furyl)[1,2,4]triazolo-[2,3-a][1,3,5]triazin-5-ylamino]ethyl}phenol (ZM241385) (50 nM) consistently reduced the actions of both agonists. In contrast to CGS21680C, NECA-induced relaxation was attenuated when endothelial production of NO and prostanoids was reduced by 100 microM N(G)-nitro-l-arginine and 10 microM indomethacin, respectively. HCC strips from patients with vasculogenic ED were partially resistant to NECA but kept relaxation to CGS21680C; the remaining effect was sensitive to blockade of A(2A) receptors with 50 nM ZM241385. Data suggest that adenosine regulates HCC smooth muscle tone through the activation of two receptor populations, CGS21680C-sensitive (A(2A)) and -insensitive (A(2B)) receptors, located on smooth muscle fibers and on endothelial cells, respectively. Endothelial dysfunction may be correlated with a loss of adenosine A(2B) receptor activity in penile vessels from men with vasculogenic ED.
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Affiliation(s)
- Miguel Faria
- Laboratório de Farmacologia, Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, L. Prof. Abel Salazar 2, 4099-003 Porto, Portugal
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Yan L, Burbiel JC, Maass A, Müller CE. Adenosine receptor agonists: from basic medicinal chemistry to clinical development. Expert Opin Emerg Drugs 2005; 8:537-76. [PMID: 14662005 DOI: 10.1517/14728214.8.2.537] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Adenosine is a physiological nucleoside which acts as an autocoid and activates G protein-coupled membrane receptors, designated A(1), A(2A), A(2B) and A(3). Adenosine plays an important role in many (patho)physiological conditions in the CNS as well as in peripheral organs and tissues. Adenosine receptors are present on virtually every cell. However, receptor subtype distribution and densities vary greatly. Adenosine itself is used as a therapeutic agent for the treatment of supraventricular paroxysmal tachycardia and arrhythmias and as a vasodilatatory agent in cardiac imaging. During the past 20 years, a number of selective agonists for A(1), A(2A) and A(3) adenosine receptors have been developed, all of them structurally derived from adenosine. Several such compounds are currently undergoing clinical trials for the treatment of cardiovascular diseases (A(1)and A(2A)), pain (A(1)), wound healing (A(2A)), diabetic foot ulcers (A(2A)), colorectal cancer (A(3)) and rheumatoid arthritis (A(3)). Clinical evaluation of some A(1) and A(2A) adenosine receptor agonists has been discontinued. Major problems include side effects due to the wide distribution of adenosine receptors; low brain penetration, which is important for the targeting of CNS diseases; short half-lifes of compounds; or a lack of effects, in some cases perhaps due to receptor desensitisation or to low receptor density in the targeted tissue. Partial agonists, inhibitors of adenosine metabolism (adenosine kinase and deaminase inhibitors) or allosteric activators of adenosine receptors may be advantageous for certain indications, as they may exhibit fewer side effects.
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Affiliation(s)
- Luo Yan
- University of Bonn, Pharmaceutical Institute Poppelsdorf, Kreuzbergweg 26, D-53115 Bonn, Germany
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Scaramuzzi RJ, Baker DJ. Possible therapeutic benefits of adenosine-potentiating drugs in reducing age-related degenerative disease in dogs and cats. J Vet Pharmacol Ther 2003; 26:327-35. [PMID: 14633184 DOI: 10.1046/j.1365-2885.2003.00527.x] [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: 12/17/2022]
Abstract
Adenosine is a ubiquitous, biologically important molecule that is a precursor of other biologically active molecules. It also is a component of some co-factors and has distinct physiological actions in its own right. Levels are maintained by synthesis from dietary precursors and re-cycling. The daily turnover of adenosine is very high. Adenosine can act either as a hormone by binding to adenosine receptors, four adenosine receptor subtypes have been identified, and as an intracellular modulator, after transport into the cell by membrane transporter proteins. One of the principal intracellular actions of adenosine is inhibition of the enzyme phosphodiesterase. Extracellular adenosine also has specific neuromodulatory actions on dopamine and glutamate. Selective and nonselective agonists and antagonists of adenosine are available. The tasks of developing, evaluating and exploiting the therapeutic potential of these compounds is still in its infancy. Adenosine has actions in the central nervous system (CNS), heart and vascular system, skeletal muscle and the immune system and the presence of receptors suggests potential actions in the gonads and other organs. Adenosine agonists improve tissue perfusion through actions on vascular smooth muscle and erythrocyte fluidity and they can be used to improve the quality of life in aged dogs. This article reviews the therapeutic potential of adenosine-potentiating drugs in the treatment of age-related conditions in companion animals, some of which may be exacerbated by castration or spaying at an early age.
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Affiliation(s)
- R J Scaramuzzi
- Department of Veterinary Basic Sciences, Royal Veterinary College, London, UK.
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Abstract
Snake envenomation employs three well integrated strategies: prey immobilization via hypotension, prey immobilization via paralysis, and prey digestion. Purines (adenosine, guanosine and inosine) evidently play a central role in the envenomation strategies of most advanced snakes. Purines constitute the perfect multifunctional toxins, participating simultaneously in all three envenomation strategies. Because they are endogenous regulatory compounds in all vertebrates, it is impossible for any prey organism to develop resistance to them. Purine generation from endogenous precursors in the prey explains the presence of many hitherto unexplained enzyme activities in snake venoms: 5'-nucleotidase, endonucleases (including ribonuclease), phosphodiesterase, ATPase, ADPase, phosphomonoesterase, and NADase. Phospholipases A(2), cytotoxins, myotoxins, and heparinase also participate in purine liberation, in addition to their better known functions. Adenosine contributes to prey immobilization by activation of neuronal adenosine A(1) receptors, suppressing acetylcholine release from motor neurons and excitatory neurotransmitters from central sites. It also exacerbates venom-induced hypotension by activating A(2) receptors in the vasculature. Adenosine and inosine both activate mast cell A(3) receptors, liberating vasoactive substances and increasing vascular permeability. Guanosine probably contributes to hypotension, by augmenting vascular endothelial cGMP levels via an unknown mechanism. Novel functions are suggested for toxins that act upon blood coagulation factors, including nitric oxide production, using the prey's carboxypeptidases. Leucine aminopeptidase may link venom hemorrhagic metalloproteases and endogenous chymotrypsin-like proteases with venom L-amino acid oxidase (LAO), accelerating the latter. The primary function of LAO is probably to promote prey hypotension by activating soluble guanylate cyclase in the presence of superoxide dismutase. LAO's apoptotic activity, too slow to be relevant to prey capture, is undoubtedly secondary and probably serves principally a digestive function. It is concluded that the principal function of L-type Ca(2+) channel antagonists and muscarinic toxins, in Dendroaspis venoms, and acetylcholinesterase in other elapid venoms, is to promote hypotension. Venom dipeptidyl peptidase IV-like enzymes probably also contribute to hypotension by destroying vasoconstrictive peptides such as Peptide YY, neuropeptide Y and substance P. Purines apparently bind to other toxins which then serve as molecular chaperones to deposit the bound purines at specific subsets of purine receptors. The assignment of pharmacological activities such as transient neurotransmitter suppression, histamine release and antinociception, to a variety of proteinaceous toxins, is probably erroneous. Such effects are probably due instead to purines bound to these toxins, and/or to free venom purines.
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Affiliation(s)
- Steven D Aird
- Laboratório de Toxinas Naturais, Universidade Estadual do Ceará, Avenida Paranjana, 1700, Itaperí, 60740-000, Fortaleza, CE, Brazil.
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Noto T, Inoue H, Mochida H, Kikkawa K. Role of adenosine and P2 receptors in the penile tumescence in anesthetized dogs. Eur J Pharmacol 2001; 425:51-5. [PMID: 11672574 DOI: 10.1016/s0014-2999(01)01167-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We studied the role of adenosine and P2 receptors in the pelvic nerve stimulation-induced penile tumescence in anesthetized dogs. A local intracavernous injection of adenosine induced the tumescence, which was abolished by intracavernous 8-(p-sulfophenyl)theophylline (8-SPT), an unspecific adenosine receptor antagonist, and by 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-yl amino]ethyl)phenol (ZM241385), an adenosine A(2A) receptor antagonist. ATP also induced the tumescence, which was diminished by 8-SPT, but not by reactive blue-2, a P2 receptor antagonist. Neither intracavernous beta, gamma-meATP nor ADP(beta)S, P2X and P2Y receptor agonists, induced tumescence. N(G)-nitro-L-arginine (L-NAME), a nitric oxide synthase inhibitor, and T-1032, a phosphodiesterase type V inhibitor, had no effects on the tumescence induced by adenosine. 8-SPT and reactive blue-2 had no effects on the tumescence induced by pelvic nerve stimulation. These results show that although exogenous adenosine and ATP induce tumescence, neither the adenosine nor the P2 receptor is involved in the tumescence induced by pelvic nerve stimulation in anesthetized dogs.
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Affiliation(s)
- T Noto
- Discovery Research Laboratory, Tanabe Seiyaku Co., Ltd., 2-2-50, Kawagishi, Toda, Saitama 335-8505, Japan.
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Antunes E, Gordo WM, de Oliveira JF, Teixeira CE, Hyslop S, De Nucci G. The relaxation of isolated rabbit corpus cavernosum by the herbal medicine Catuama and its constituents. Phytother Res 2001; 15:416-21. [PMID: 11507734 DOI: 10.1002/ptr.861] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The effects of the Brazilian herbal medicine Catuama and each of its plant constituents (Paullinia cupana, Trichilia catigua, Zingiber officinalis and Ptychopetalum olacoides) were investigated on rabbit corpus cavernosum (RbCC) using a bioassay cascade. Catuama caused short-lived and dose-dependent relaxations (11% +/- 7%, 26% +/- 5% and 82% +/- 9%, at doses of 1, 3 and 10 mg, respectively). Neither the nitric oxide synthesis inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME; 10 microM) nor the soluble guanylate cyclase inhibitor ODQ (10 microM) significantly affected the Catuama-induced relaxations. Similarly, the selective ATP-dependent K(+) channel (K(ATP)) blocker glibenclamide (10 microM), the muscarinic receptor antagonist atropine (1 microM) and the voltage-dependent Na(+) channel blocker tetrodotoxin (1 microM) all failed to affect significantly the Catuama-induced relaxations. These results indicate that the relaxations induced by Catuama involve neither nitric oxide release nor K(ATP) channel activation. The extracts of P. cupana, Z. officinalis and P. olacoides caused short-lived and dose-dependent RbCC relaxations, whereas T. catigua evoked long-lasting relaxations which were occasionally preceded by a brief contractile effect. The extract of P. cupana was the most active in relaxing RbCC strips. The relaxations induced by all extracts were not significantly affected by L-NAME (10 microM). The infusion of ODQ (10 microM) had no significant effect on the P. cupana- and Z. officinalis-induced relaxations but reduced by >50% (p < 0.05) those evoked by P. olacoides and T. catigua. Incubations of RbCC with Catuama(10 mg/mL for 0.25 to 5 min) caused increases of cAMP levels (143% increase at 5 min of incubation). Incubations of RbCC with P. cupana extract (1 mg/mL) increased the cAMP levels by 200% whereas higher doses (10 and 100 mg/mL) caused smaller increases in the nucleotide levels (150% and 89%, respectively). The extracts of Z. officinalis and P. olacoides (same doses) caused smaller increases of the cAMP levels compared with the P. cupana extract, whereas T. catigua (1-100 mg) did not increase the levels of this nucleotide above the basal values. Our results show that of the four extracts assayed, P. cupana was the most effective, indicating that it is the main extract responsible for the relaxing effect of Catuama on rabbit cavernosal tissue.
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Affiliation(s)
- E Antunes
- Department of Pharmacology, Faculty of Medical Sciences, UNICAMP, P.O. Box 6111, 13081-970, Campinas (SP), Brazil.
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Baraldi PG, Cacciari B, Romagnoli R, Klotz KN, Spalluto G, Varani K, Gessi S, Merighi S, Borea PA. Pyrazolo[4,3-e]1,2,4-triazolo[1,5-c]pyrimidine derivatives as adenosine receptor ligands: A starting point for searching A2B adenosine receptor antagonists. Drug Dev Res 2001. [DOI: 10.1002/ddr.1191] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Gürke L, Mattei A, Chaloupka K, Marx A, Sutter PM, Stierli P, Harder F, Heberer M. Mechanisms of ischemic preconditioning in skeletal muscle. J Surg Res 2000; 94:18-27. [PMID: 11038298 DOI: 10.1006/jsre.2000.5987] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Ischemic preconditioning (IP) (one or more cycles each consisting of a short period of ischemia and a short period of reperfusion, before the sustained ischemia) reduces ischemia-related organ damage in heart and skeletal muscle but the underlying mechanisms are not clear. This study was intended to assess the possible involvement of K(ATP) channels and of adenosine receptors in IP of skeletal muscle in a rat model of skeletal muscle ischemia. MATERIALS AND METHODS Groups of 8-15 rats were given the following in vivo treatments: ischemia-reperfusion (I-R: 2.5 h tourniquet-induced ischemia of the right hindlimb, then 2 h reperfusion); IP (three cycles of 5 min ischemia, then 5 min reperfusion) before I-R; cromakalim and I-R; glibenclamide, cromakalim, and I-R; glibenclamide, IP, and I-R; [R]-N(6)-[1-methyl-2-phenylethyl]adenosine (R-PIA) and I-R; adenosine and I-R; and glibenclamide, IP, and I-R. Parameters of muscle function (postischemic maximal force, performance, contraction index, and force after 1 min of stimulation) were then assessed in vitro in the extensor digitorum longus muscle. RESULTS Pretreatment with either IP or the K(ATP) channel opener cromakalim significantly improved postischemic muscle function. The protective effect of cromakalim was not seen when the K(ATP) channel blocker glibenclamide was added. Glibenclamide, however, did not block IP-induced protection. Pretreatment with the adenosine A(1) receptor agonist 8-(p-sulfophenyl)-theophyllin (8-SPT) or with adenosine did not improve postischemic muscle function. The adenosine receptor agonist did not block IP-induced protection against ischemic damage. CONCLUSIONS The results show significant improvements in postischemic skeletal muscle function after IP or cromakalim pretreatment but they do not support a role for K(ATP) channels or for adenosine receptors in IP of skeletal muscle.
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Affiliation(s)
- L Gürke
- Department of Surgery, University of Basel, Basel, Switzerland.
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Abstract
Over the past two decades our understanding of the physiology and the various mediators involved in the pathway of penile erection has greatly increased. This has enabled us to develop effective pharmacological treatments for ED.
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Affiliation(s)
- M A Khan
- Department of Urology, Royal Free and University College Medical School (University College London), Royal Free Campus and Royal Free Hampstead NHS Trust, London, UK
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Affiliation(s)
- Igor Feoktistov
- Divisions of Clinical Pharmacology and Cardiology, Departments of Medicine and Pharmacology, Vanderbilt University, Nashville, Tennessee
| | - Jack N. Wells
- Divisions of Clinical Pharmacology and Cardiology, Departments of Medicine and Pharmacology, Vanderbilt University, Nashville, Tennessee
| | - Italo Biaggioni
- Divisions of Clinical Pharmacology and Cardiology, Departments of Medicine and Pharmacology, Vanderbilt University, Nashville, Tennessee
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Ayan S, Yildirim S, Uçar C, Sarioglu Y, Gültekin Y, Bütüner C. Corporal reactivity to adenosine and prostaglandin E1 in alloxan-induced diabetic rabbit corpus cavernosum, and the effect of insulin therapy. BJU Int 1999; 83:108-12. [PMID: 10233462 DOI: 10.1046/j.1464-410x.1999.00892.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To investigate the changes in corporal reactivity to adenosine and prostaglandin E1 (PGE1 ) in corpus cavernosal strips from alloxan-induced diabetic rabbits and to determine the effects of insulin therapy. MATERIALS AND METHODS Twenty-four New Zealand white rabbits were studied in three equal groups: group 1, control; group 2, diabetes induced by the administration of alloxan hydrochloride intravenously; group 3, as group 2 but with insulin administered after the induction of diabetes. At the end of 8 weeks, the reactivity of corpus cavernosal strips from the animals was assessed in organ chambers. RESULTS The relaxation responses of corpus cavernosal strips to adenosine were similar in all groups, but the response to PGE1 was impaired in groups 2 and 3 compared with that in controls. CONCLUSION If vasoactive drugs are to be used for the diagnosis or treatment of diabetic erectile impotence, direct-acting vasodilators, e.g. adenosine, must be used. In alloxan-induced diabetes, the corporal reactivity to PGE1 was impaired and insulin therapy did not restore the relaxation responses.
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Affiliation(s)
- S Ayan
- Department of Urology, Cumhuriyet University, Sivas, Turkey
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FILIPPI SANDRA, AMERINI SANDRA, MAGGI MARIO, NATALI ALESSANDRO, LEDDA FABRIZIO. STUDIES ON THE MECHANISMS INVOLVED IN THE ATP-INDUCED RELAXATION IN HUMAN AND RABBIT CORPUS CAVERNOSUM. J Urol 1999. [DOI: 10.1016/s0022-5347(01)62140-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- SANDRA FILIPPI
- Department of Pharmacology, Andrology Unit, and Urology Unit, University of Florence, Florence, Italy
| | - SANDRA AMERINI
- Department of Pharmacology, Andrology Unit, and Urology Unit, University of Florence, Florence, Italy
| | - MARIO MAGGI
- Department of Pharmacology, Andrology Unit, and Urology Unit, University of Florence, Florence, Italy
| | - ALESSANDRO NATALI
- Department of Pharmacology, Andrology Unit, and Urology Unit, University of Florence, Florence, Italy
| | - FABRIZIO LEDDA
- Department of Pharmacology, Andrology Unit, and Urology Unit, University of Florence, Florence, Italy
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Feoktistov I, Biaggioni I. Pharmacological characterization of adenosine A2B receptors: studies in human mast cells co-expressing A2A and A2B adenosine receptor subtypes. Biochem Pharmacol 1998; 55:627-33. [PMID: 9515573 DOI: 10.1016/s0006-2952(97)00512-1] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Characterization of A2B receptors is hampered by the lack of selective pharmacological probes and often relies on their relative affinity to agonists that are selective at other receptor types. This approach is limited because the affinity of A2B receptors for putative A3 agonists has not been determined. Using the human erythroleukemia cell line HEL as a cellular model for A2B-mediated adenylate cyclase activation, we found the following potencies (pD2) for the non-selective agonist 5'-N-ethylcarboxamidoadenosine (NECA) (5.65 +/- 0.04), the putative A3 agonists N6-benzyl-NECA (4.17 +/- 0.06) and N6-(3-iodobenzyl)-N-methyl-5'-carbamoyladenosine (IB-MECA) (3.7 +/- 0.02), and the A2A agonist 4-[(N-ethyl-5'-carbamoyladenos-2-yl)-aminoethyl]-phenylpropionic acid (CGS21680) (2.8 +/- 0.1). Because of the lack of a selective agonist, characterization of A2B receptor function is difficult in cells co-expressing A2A receptors. In the human mast cell line HMC-1, NECA induced cAMP accumulation with a concentration-response relationship best fitted to a two-sited model (pD2 7.69 +/- 0.42 and 5.92 +/- 0.21 for high- and low-affinity sites), suggesting the presence of both A2A and A2B receptors in these cells. We demonstrated that A2B receptors can be selectively activated with NECA in the presence of the selective A2A antagonist 5-amino-7-(phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c ]pyrimidine (SCH 58261). Under these conditions, the concentration-response relationship of NECA for cyclic AMP accumulation was now best fitted to a one-site model (pD2 5.68 +/- 0.03, Hill slope 0.93 +/- 0.06, 95% confidence intervals 0.8 to 1.06) corresponding to selective activation of A2B receptors. Using the approaches developed in this study, we determined that A2B, and not A2A or A3, receptors account for all the calcium mobilization induced by NECA in HMC-1 cells.
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Affiliation(s)
- I Feoktistov
- Department of Medicine, Vanderbilt University, Nashville, TN 37232-2195, USA
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