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Papay RS, Macdonald JD, Stauffer SR, Perez DM. Characterization of a novel positive allosteric modulator of the α 1A-Adrenergic receptor. CURRENT RESEARCH IN PHARMACOLOGY AND DRUG DISCOVERY 2022; 4:100142. [PMID: 36544813 PMCID: PMC9762201 DOI: 10.1016/j.crphar.2022.100142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 10/27/2022] [Accepted: 11/15/2022] [Indexed: 12/05/2022] Open
Abstract
α1-Adrenergic Receptors (ARs) are G-protein Coupled Receptors (GPCRs) that regulate the sympathetic nervous system via the binding and activation of norepinephrine (NE) and epinephrine (Epi). α1-ARs control various aspects of neurotransmission, cognition, cardiovascular functions as well as other organ systems. However, therapeutic drug development for these receptors, particularly agonists, has been stagnant due to unwanted effects on blood pressure regulation. We report the synthesis and characterization of the first positive allosteric modulator (PAM) for the α1-AR based upon the derivation of the α1A-AR selective imidazoline agonist, cirazoline. Compound 3 (Cmpd-3) binds the α1A-AR with high and low affinity sites (0.13pM; 54 nM) typical of GPCR agonists, and reverts to a single low affinity site of 100 nM upon the addition of GTP. Comparison of Cmpd-3 versus other orthosteric α1A-AR-selective imidazoline ligands reveal unique properties that are consistent with a type I PAM. Cmpd-3 is both conformationally and ligand-selective for the α1A-AR subtype. In competition binding studies, Cmpd-3 potentiates NE-binding at the α1A-AR only on the high affinity state of NE with no effect on the Epi-bound α1A-AR. Moreover, Cmpd-3 demonstrates signaling-bias and potentiates the NE-mediated cAMP response of the α1A-AR at nM concentrations with no effects on the NE-mediated inositol phosphate response. There are no effects of Cmpd-3 on the signaling at the α1B- or α1D-AR subtypes. Cmpd-3 displays characteristics of a pure PAM with no intrinsic agonist properties. Specific derivation of Cmpd-3 at the R1 ortho-position recapitulated PAM characteristics. Our results characterize the first PAM for the α1-AR and holds promise for a first-in-class therapeutic to treat various diseases without the side effect of increasing blood pressure intrinsic to classical orthosteric agonists.
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Affiliation(s)
- Robert S. Papay
- The Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH, 44195, USA
| | - Jonathan D. Macdonald
- Center for Therapeutics Discovery, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH, 44195, USA
| | - Shaun R. Stauffer
- Center for Therapeutics Discovery, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH, 44195, USA
| | - Dianne M. Perez
- The Department of Cardiovascular & Metabolic Sciences, Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH, 44195, USA
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Dalmagro AP, Holzmann I, Zimath PL, Cazarin CA, Souza MMD. Antidepressant-like effect of caffeic acid: Involvement of the cellular signaling pathways. BRAZ J PHARM SCI 2022. [DOI: 10.1590/s2175-97902022e20023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Song W, Zhao YY, Ren YJ, Liu LL, Wei SD, Yang HB. Proanthocyanidins isolated from the leaves of Photinia × fraseri block the cell cycle and induce apoptosis by inhibiting tyrosinase activity in melanoma cells. Food Funct 2021; 12:3978-3991. [PMID: 33977989 DOI: 10.1039/d1fo00134e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Tyrosinase is considered a molecular marker of melanoma, and few natural antitumor drugs targeting tyrosinase have been identified. In this study, proanthocyanidins (PAs) were isolated from the leaves of Photinia × fraseri and their structures were characterized by high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and the effects of antityrosinase activity were investigated. The results showed that the basic structural units of PAs are composed of catechin and epicatechin and that oligomer is the main component. PAs exhibited better antityrosinase activity via chelation of copper ions and by disturbing o-quinone production. Furthermore, analyses of the cell cycle, apoptosis rate, and regulation of melanin protein expression revealed preliminarily that PAs could affect melanin production by downregulating microphthalmia transcription factor (MITF) expression and by inhibiting the activities of tyrosinase and tyrosinase related protein 1 (TRP-1), leading to cell cycle arrest and apoptosis of melanoma cells. Collectively, our study demonstrated that PAs are potential tyrosinase inhibitors and have good antimelanoma effects. These findings provide a theoretical support for the application of tyrosinase inhibitors and for further drug development.
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Affiliation(s)
- Wei Song
- School of Life Science and Engineering, Henan University of Urban Construction, Pingdingshan, Henan 467044, China.
| | - Ya-Ying Zhao
- School of Life Science and Engineering, Henan University of Urban Construction, Pingdingshan, Henan 467044, China. and College of Life Science, Yangtze University, Jingzhou, Hubei 434025, China.
| | - Yuan-Jing Ren
- School of Life Science and Engineering, Henan University of Urban Construction, Pingdingshan, Henan 467044, China. and College of Life Science, Yangtze University, Jingzhou, Hubei 434025, China.
| | - Lu-Lu Liu
- School of Life Science and Engineering, Henan University of Urban Construction, Pingdingshan, Henan 467044, China. and College of Life Science, Yangtze University, Jingzhou, Hubei 434025, China.
| | - Shu-Dong Wei
- College of Life Science, Yangtze University, Jingzhou, Hubei 434025, China.
| | - Hai-Bo Yang
- School of Life Science and Engineering, Henan University of Urban Construction, Pingdingshan, Henan 467044, China. and Forestry College, Henan Agricultural University, Zhengzhou, Henan 450000, China
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Scheau C, Draghici C, Ilie MA, Lupu M, Solomon I, Tampa M, Georgescu SR, Caruntu A, Constantin C, Neagu M, Caruntu C. Neuroendocrine Factors in Melanoma Pathogenesis. Cancers (Basel) 2021; 13:cancers13092277. [PMID: 34068618 PMCID: PMC8126040 DOI: 10.3390/cancers13092277] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Revised: 05/03/2021] [Accepted: 05/05/2021] [Indexed: 12/15/2022] Open
Abstract
Simple Summary Melanoma is a very aggressive and fatal malignant tumor. While curable if diagnosed in its early stages, advanced melanoma, despite the complex therapeutic approaches, is associated with one of the highest mortality rates. Hence, more and more studies have focused on mechanisms that may contribute to melanoma development and progression. Various studies suggest a role played by neuroendocrine factors which can act directly on tumor cells, modulating their proliferation and metastasis capability, or indirectly through immune or inflammatory processes that impact disease progression. However, there are still multiple areas to explore and numerous unknown features to uncover. A detailed exploration of the mechanisms by which neuroendocrine factors can influence the clinical course of the disease could open up new areas of biomedical research and may lead to the development of new therapeutic approaches in melanoma. Abstract Melanoma is one of the most aggressive skin cancers with a sharp rise in incidence in the last decades, especially in young people. Recognized as a significant public health issue, melanoma is studied with increasing interest as new discoveries in molecular signaling and receptor modulation unlock innovative treatment options. Stress exposure is recognized as an important component in the immune-inflammatory interplay that can alter the progression of melanoma by regulating the release of neuroendocrine factors. Various neurotransmitters, such as catecholamines, glutamate, serotonin, or cannabinoids have also been assessed in experimental studies for their involvement in the biology of melanoma. Alpha-MSH and other neurohormones, as well as neuropeptides including substance P, CGRP, enkephalin, beta-endorphin, and even cellular and molecular agents (mast cells and nitric oxide, respectively), have all been implicated as potential factors in the development, growth, invasion, and dissemination of melanoma in a variety of in vitro and in vivo studies. In this review, we provide an overview of current evidence regarding the intricate effects of neuroendocrine factors in melanoma, including data reported in recent clinical trials, exploring the mechanisms involved, signaling pathways, and the recorded range of effects.
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Affiliation(s)
- Cristian Scheau
- Department of Physiology, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania; (C.S.); (C.C.)
| | - Carmen Draghici
- Dermatology Research Laboratory, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania; (C.D.); (M.A.I.); (M.L.); (I.S.)
| | - Mihaela Adriana Ilie
- Dermatology Research Laboratory, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania; (C.D.); (M.A.I.); (M.L.); (I.S.)
| | - Mihai Lupu
- Dermatology Research Laboratory, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania; (C.D.); (M.A.I.); (M.L.); (I.S.)
| | - Iulia Solomon
- Dermatology Research Laboratory, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania; (C.D.); (M.A.I.); (M.L.); (I.S.)
| | - Mircea Tampa
- Department of Dermatology, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania; (M.T.); (S.R.G.)
| | - Simona Roxana Georgescu
- Department of Dermatology, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania; (M.T.); (S.R.G.)
| | - Ana Caruntu
- Department of Oral and Maxillofacial Surgery, “Carol Davila” Central Military Emergency Hospital, 010825 Bucharest, Romania
- Department of Oral and Maxillofacial Surgery, Faculty of Dental Medicine, “Titu Maiorescu” University, 031593 Bucharest, Romania
- Correspondence:
| | - Carolina Constantin
- Immunology Department, Victor Babes National Institute of Pathology, 050096 Bucharest, Romania; (C.C.); (M.N.)
- Department of Pathology, Colentina University Hospital, 020125 Bucharest, Romania
| | - Monica Neagu
- Immunology Department, Victor Babes National Institute of Pathology, 050096 Bucharest, Romania; (C.C.); (M.N.)
- Department of Pathology, Colentina University Hospital, 020125 Bucharest, Romania
- Faculty of Biology, University of Bucharest, 076201 Bucharest, Romania
| | - Constantin Caruntu
- Department of Physiology, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania; (C.S.); (C.C.)
- Department of Dermatology, “Prof. N. Paulescu” National Institute of Diabetes, Nutrition and Metabolic Diseases, 011233 Bucharest, Romania
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Wong A, Frøslev T, Dearing L, Forbes H, Mulick A, Mansfield K, Silverwood R, Kjærsgaard A, Sørensen H, Smeeth L, Lewin A, Schmidt S, Langan S. The association between partner bereavement and melanoma: cohort studies in the U.K. and Denmark. Br J Dermatol 2020; 183:673-683. [PMID: 32128788 PMCID: PMC7587014 DOI: 10.1111/bjd.18889] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/18/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Psychological stress is commonly cited as a risk factor for melanoma, but clinical evidence is limited. OBJECTIVES This study aimed to evaluate the association between partner bereavement and (i) first-time melanoma diagnosis and (ii) mortality in patients with melanoma. METHODS We conducted two cohort studies using data from the U.K. Clinical Practice Research Datalink (1997-2017) and Danish nationwide registries (1997-2016). In study 1, we compared the risk of first melanoma diagnosis in bereaved vs. matched nonbereaved people using stratified Cox regression. In study 2 we estimated hazard ratios (HRs) for death from melanoma in bereaved compared with nonbereaved individuals with melanoma using Cox regression. We estimated HRs separately for the U.K. and for Denmark, and then pooled the data to perform a random-effects meta-analysis. RESULTS In study 1, the pooled adjusted HR for the association between partner bereavement and melanoma diagnosis was 0·88 [95% confidence interval (CI) 0·84-0·92] across the entire follow-up period. In study 2, we observed increased melanoma-specific mortality in people experiencing partner bereavement across the entire follow-up period (HR 1·17, 95% CI 1·06-1·30), with the peak occurring during the first year of follow-up (HR 1·31, 95% CI 1·07-1·60). CONCLUSIONS We found decreased risk of melanoma diagnosis, but increased mortality associated with partner bereavement. These findings may be partly explained by delayed detection resulting from the loss of a partner who could notice skin changes. Stress may play a role in melanoma progression. Our findings indicate the need for a low threshold for skin examination in individuals whose partners have died. What is already known about this topic? Psychological stress has been proposed as a risk factor for the development and progression of cancer, including melanoma, but evidence is conflicting. Clinical evidence is limited by small sample sizes, potential recall bias associated with self-report, and heterogeneous stress definitions. What does this study add? We found a decreased risk of melanoma diagnosis, but increased mortality associated with partner bereavement. While stress might play a role in the progression of melanoma, an alternative explanation is that bereaved people no longer have a close person to help notice skin changes, leading to delayed melanoma detection. Linked Comment: Talaganis et al. Br J Dermatol 2020; 183:607-608.
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Affiliation(s)
- A.Y.S. Wong
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical MedicineLondonU.K
| | - T. Frøslev
- Department of Clinical EpidemiologyAarhus University HospitalAarhusDenmark
| | - L. Dearing
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical MedicineLondonU.K
| | - H.J. Forbes
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical MedicineLondonU.K
- Health Data Research UKLondonU.K
| | - A. Mulick
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical MedicineLondonU.K
| | - K.E. Mansfield
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical MedicineLondonU.K
| | - R.J. Silverwood
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical MedicineLondonU.K
- Centre for Longitudinal StudiesDepartment of Social ScienceUniversity College LondonLondonU.K
| | - A. Kjærsgaard
- Department of Clinical EpidemiologyAarhus University HospitalAarhusDenmark
| | - H.T. Sørensen
- Department of Clinical EpidemiologyAarhus University HospitalAarhusDenmark
| | - L. Smeeth
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical MedicineLondonU.K
- Health Data Research UKLondonU.K
| | - A. Lewin
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical MedicineLondonU.K
| | - S.A.J. Schmidt
- Department of Clinical EpidemiologyAarhus University HospitalAarhusDenmark
- Department of DermatologyAarhus University HospitalAarhusDenmark
| | - S.M. Langan
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical MedicineLondonU.K
- Health Data Research UKLondonU.K
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Gabriel EM, Kim M, Fisher DT, Powers C, Attwood K, Bagaria SP, Knutson KL, Skitzki JJ. Dynamic control of tumor vasculature improves antitumor responses in a regional model of melanoma. Sci Rep 2020; 10:13245. [PMID: 32764623 PMCID: PMC7413248 DOI: 10.1038/s41598-020-70233-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 07/24/2020] [Indexed: 11/09/2022] Open
Abstract
Despite advances in therapy for melanoma, heterogeneous responses with limited durability represent a major gap in treatment outcomes. The purpose of this study was to determine whether alteration in tumor blood flow could augment drug delivery and improve antitumor responses in a regional model of melanoma. This approach to altering tumor blood flow was termed "dynamic control." Dynamic control of tumor vessels in C57BL/6 mice bearing B16 melanoma was performed using volume expansion (saline bolus) followed by phenylephrine. Intravital microscopy (IVM) was used to observe changes directly in real time. Our approach restored blood flow in non-functional tumor vessels. It also resulted in increased chemotherapy (melphalan) activity, as measured by formation of DNA adducts. The combination of dynamic control and melphalan resulted in superior outcomes compared to melphalan alone (median time to event 40.0 vs 25.0 days, respectively, p = 0.041). Moreover, 25% (3/12) of the mice treated with the combination approach showed complete tumor response. Importantly, dynamic control plus melphalan did not result in increased adverse events. In summary, we showed that dynamic control was feasible, directly observable, and augmented antitumor responses in a regional model of melanoma. Early clinical trials to determine the translational feasibility of dynamic control are ongoing.
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Affiliation(s)
- Emmanuel M Gabriel
- Department of Surgery, Section of Surgical Oncology, Mayo Clinic Florida, 4500 San Pablo Road, Jacksonville, FL, 32224, USA.
| | - Minhyung Kim
- Department of Immunology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Daniel T Fisher
- Department of Immunology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Colin Powers
- Department of Immunology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Kristopher Attwood
- Department of Biostatistics, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
| | - Sanjay P Bagaria
- Department of Surgery, Section of Surgical Oncology, Mayo Clinic Florida, 4500 San Pablo Road, Jacksonville, FL, 32224, USA
| | - Keith L Knutson
- Department of Immunology, Mayo Clinic, Jacksonville, FL, USA
| | - Joseph J Skitzki
- Department of Surgical Oncology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, USA
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Stress as a possible mechanism in melanoma progression. Dermatol Res Pract 2010; 2010:483493. [PMID: 20585601 PMCID: PMC2878675 DOI: 10.1155/2010/483493] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 03/15/2010] [Indexed: 01/04/2023] Open
Abstract
The incidence of melanoma, the most aggressive type of cutaneous malignant tumor, is currently on the rise. Treatment in advanced stages is still unsuccessful compared with other malignant tumors, thus it is important to indentify the key mechanisms responsible for melanoma progression and metastasis. Genetic and molecular components, in particular, that are up- or downregulated in melanoma cells, affect the invasive potential of melanoma. Another possible important cofactor highlighted by recent studies is chronic stress, involving environmental and psychological factors, which can be an important cofactor in not only cancer progression in general but also in melanoma spreading. The negative effects of chronic stress have been evaluated epidemiologically in patients with breast and prostate cancer. In particular, the effects of stress mediators, namely, catecholamines have been studied on various human malignancies, including melanoma and have highlighted a significant increase of progression-related molecules. As such, this could be the starting point for a new approach in the treatment of advanced melanoma, in which the negative effects of stress are reduced or blocked.
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Epinephrine-induced hyperpolarization of pancreatic islet cells is sensitive to PI3K-PDK1 signaling. FEBS Lett 2009; 583:3101-6. [DOI: 10.1016/j.febslet.2009.08.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 08/20/2009] [Accepted: 08/22/2009] [Indexed: 02/02/2023]
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Schraml E, Fuchs R, Kotzbeck P, Grillari J, Schauenstein K. Acute adrenergic stress inhibits proliferation of murine hematopoietic progenitor cells via p38/MAPK signaling. Stem Cells Dev 2009; 18:215-27. [PMID: 18444787 DOI: 10.1089/scd.2008.0072] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Acute adrenergic stress is a cause of hematopoietic failure that accompanies severe injury. Although the communication between neuronal and immune system is well documented and catecholamines are known as important regulators of homeostasis, the molecular mechanisms of hematopoietic failure are not well understood. To study the influence of adrenergic stress on hematopoietic progenitor cells (HPCs), which recently have been found to express adrenergic receptors, Lin(-),Sca(+), cells were isolated and treated with alpha- and beta-adrenergic agonists in vitro. Indeed, this stimulation resulted in significantly decreased colony formation capacity using granulocyte/macrophage colony-forming unit assays. This decline was dependent on the formation of reactive oxygen species (ROS) and activation of the p38/mitogen-activated protein kinase (MAPK) pathway, since the addition of antioxidants or a p38 inhibitor restored CFU formation. DNA damage by adrenergically induced ROS, however, does not seem to account for the reduction of colonies. Thus, catecholamine/p38/MAPK is identified as a key signal transduction pathway in HPCs besides those dependent on Wnt, Notch, and sonic hedgehog. Furthermore, a well-known target of p38 signaling, p16 is transcriptionally activated after adrenergic stimulation, suggesting that cell cycle arrest might importantly contribute to hematopoietic failure and immune dysfunctions after severe injury. Since increased levels of catecholamines are also observed in other conditions, such as during aging which is linked with decline of immune functions, adrenergic stress might as well contribute to the lowered immune defence in the elderly.
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Affiliation(s)
- Elisabeth Schraml
- Institute of Pathophysiology and Immunology, Center of Molecular Medicine, Medical University of Graz, Graz, Austria.
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Oxidative stress and alpha1-adrenoceptor-mediated stimulation of the Cl-/HCO3- exchanger in immortalized SHR proximal tubular epithelial cells. Br J Pharmacol 2008; 153:1445-55. [PMID: 18297111 DOI: 10.1038/bjp.2008.16] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND AND PURPOSE This study evaluated the signalling coupled to the alpha1-adrenoceptor-induced stimulation of the Cl-/HCO3- exchanger in hypertension. EXPERIMENTAL APPROACH The Na+ -independent HCO3- transport system activity was assayed as the initial rate of pHi recovery after an alkaline load (CO2/HCO3 removal) in immortalized renal proximal tubular epithelial cells from spontaneously hypertensive rat (SHR) and their normotensive control (Wistar Kyoto rat; WKY). KEY RESULTS Noradrenaline increased Cl-/HCO3- exchanger activity with EC50 values of 0.6 and 5.3 microM in SHR and WKY cells, respectively. These effects were abolished by prazosin, but not by yohimbine. Phenylephrine increased Cl-/HCO3- exchanger activity in SHR and WKY cells (EC50 of 2.6 and 4.9 microM, respectively). Phenylephrine-mediated increase in Cl-/HCO3- exchanger activity in WKY and SHR cells was inhibited by protein kinase C (PKC), MAPK/ERK kinase (MEK) and p38 mitogen-activated protein kinase (p38 MAPK) inhibitors. The expression of alpha1A- and alpha1B-adrenoceptors was identical in WKY and SHR cells. SHR cells generated more H2O2 than WKY cells. In SHR cells, the NADPH oxidase inhibitor apocynin reduced their increased ability to generate H2O2 and abolished their hypersensitivity to phenylephrine, but failed to affect basal Cl-/HCO3- exchanger activity. H2O2-dependent stimulation of Cl-/HCO3- exchange activity was significantly higher in SHR than in WKY cells. CONCLUSIONS AND IMPLICATIONS Differences between WKY and SHR cells on their sensitivity to alpha1-adrenoceptor stimulation did not correlate with the abundance of alpha1A- and alpha1B-adrenoceptors and may be related to the increased generation of H2O2, which may amplify the response downstream of alpha1-adrenoceptor activation.
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