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Zhang B, Shen J. Dexmedetomidine activates the PKA/CREB pathway and inhibits proinflammatory factor expression through β2 adrenergic receptors. Immun Inflamm Dis 2024; 12:e1176. [PMID: 38411331 PMCID: PMC10898205 DOI: 10.1002/iid3.1176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 01/02/2024] [Accepted: 01/18/2024] [Indexed: 02/28/2024] Open
Abstract
INTRODUCTION Dexmedetomidine (DEX) is primarily utilized for sedation in the context of general anesthesia or intensive care. However, the exact regulatory mechanism by which DEX affects cytokines remains unclear. This study aims to investigate the underlying mechanism by which DEX inhibits proinflammatory factors through activation of the β2 adrenergic receptor (β2 AR). METHODS The inflammatory cell model of human mononuclear macrophage (THP-1) cells induced by lipopolysaccharide (LPS) was established to study the effect of DEX on the expression of cell-related inflammatory factors. ADRA2A gene knockout THP-1 cells (THP-1KO ) were constructed by CRISPR technology, and the effect of DEX on the expression of inflammatory factors of THP-1KO cells was detected. The target sites of DEX on β2 AR were screened by molecular docking. Reversion experiments were performed using ADRB2-siRNA. Western blot was used to detect the activation of β2 AR/PKA/CREB pathway and NF-κB, and ELISA was used to detect the release level of inflammatory factors. RESULTS The results demonstrated a significant reduction in the expression levels of MCP-1, interleukin-06, and IL-8 in both THP-1 and THP-1KO cells when induced by LPS following treatment with DEX. Additionally, DEX treatment led to an increase in IL-10 expression. Immunofluorescence analysis revealed an upregulation of β2 AR expression after DEX treatment. Western blot results indicated that DEX notably enhanced the activation of the β2 AR and PKA/CREB pathways, while concurrently suppressing the activation of NF-κB. Notably, the use of ADRB2 siRNA reversed the effects of DEX treatment and promoted the release of inflammatory cytokines. CONCLUSION DEX initiates the activation of the PKA/CREB pathway through the activation of β2 AR. Simultaneously, it exerts an inhibitory effect on the activation of NF-κB, consequently reducing the transcription of proinflammatory factors while increasing the transcription of anti-inflammatory factors.
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Affiliation(s)
- Baocheng Zhang
- Department of Emergency and Critical Care CenterJinshan Hospital Affiliated to Fudan UniversityShanghaiChina
| | - Jie Shen
- Department of Emergency and Critical Care CenterJinshan Hospital Affiliated to Fudan UniversityShanghaiChina
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Matera MG, Rinaldi B, Calzetta L, Rogliani P, Cazzola M. Advances in adrenergic receptors for the treatment of chronic obstructive pulmonary disease: 2023 update. Expert Opin Pharmacother 2023; 24:2133-2142. [PMID: 37955136 DOI: 10.1080/14656566.2023.2282673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/08/2023] [Indexed: 11/14/2023]
Abstract
INTRODUCTION Strong scientific evidence and large experience support the use of β2-agonists for the symptomatic alleviation of COPD. Therefore, there is considerable effort in discovering highly potent and selective β2-agonists. AREAS COVERED Recent research on novel β2-agonists for the treatment of COPD. A detailed literature search was performed in two major databases (PubMed/MEDLINE and Scopus) up to September 2023." EXPERT OPINION Compounds that preferentially activate a Gs- or β-arrestin-mediated signaling pathway via β- adrenoceptors (ARs) are more innovative. Pepducins, which target the intracellular region of β2-AR to modulate receptor signaling output, have the most interesting profile from a pharmacological point of view. They stabilize the conformation of the β2-AR and influence its signaling by interacting with the intracellular receptor-G protein interface. New bifunctional drugs called muscarinic antagonist-β2 agonist (MABA), which have both muscarinic receptor (mAChR) antagonism and β2-agonist activity in the same molecule, are a new opportunity. However, all tested compounds have been shown to act predominantly as mAChR antagonists or β2-agonists. An intriguing idea is to utilize allosteric modulators that bind to β2-ARs at sites different than those bound by orthosteric ligands to augment or reduce the signaling transduced by the orthosteric ligand.
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Affiliation(s)
- Maria Gabriella Matera
- Unit of Pharmacology, Department of Experimental Medicine, University of Campania 'Luigi Vanvitelli', Naples, Italy
| | - Barbara Rinaldi
- Unit of Pharmacology, Department of Experimental Medicine, University of Campania 'Luigi Vanvitelli', Naples, Italy
| | - Luigino Calzetta
- Unit of Respiratory Diseases and Lung Function, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Paola Rogliani
- Unit of Respiratory Medicine, Department of Experimental Medicine, University of Rome 'Tor Vergata', Rome, Italy
| | - Mario Cazzola
- Unit of Respiratory Medicine, Department of Experimental Medicine, University of Rome 'Tor Vergata', Rome, Italy
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Jenkins CR, Boulet LP, Lavoie KL, Raherison-Semjen C, Singh D. Reply to “Importance of β2-receptor function in premenstrual asthma”. THE JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY: IN PRACTICE 2022; 10:2776-2777. [DOI: 10.1016/j.jaip.2022.07.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 07/29/2022] [Indexed: 11/06/2022]
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Yang A, Yu G, Wu Y, Wang H. Role of β2-adrenergic receptors in chronic obstructive pulmonary disease. Life Sci 2020; 265:118864. [PMID: 33301808 DOI: 10.1016/j.lfs.2020.118864] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 11/19/2020] [Accepted: 11/29/2020] [Indexed: 01/14/2023]
Abstract
Beta-2 adrenergic receptors (β2-ARs) have important roles in the pathogenesis and treatment of chronic obstructive pulmonary disease (COPD). In recent years, progress has been made in the study of β2-ARs. Here, we introduce the basic concepts of β2-ARs, related pathways, as well as application of blockers/agonists of β2-ARs, and β2-AR autoantibodies in COPD. Drugs targeting the β2-AR are being developed rapidly, and we expect them to improve the symptoms and prognosis of COPD patients in the future.
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Affiliation(s)
- Ailin Yang
- Department of Respiratory Medicine, Beijing Friendship Hospital, Capital Medical University, 95 Yong An Road, Xicheng District, Beijing 100050, China
| | - Ganggang Yu
- Department of Respiratory Medicine, Beijing Friendship Hospital, Capital Medical University, 95 Yong An Road, Xicheng District, Beijing 100050, China
| | - Yanjun Wu
- Department of Respiratory Medicine, Beijing Friendship Hospital, Capital Medical University, 95 Yong An Road, Xicheng District, Beijing 100050, China.
| | - Haoyan Wang
- Department of Respiratory Medicine, Beijing Friendship Hospital, Capital Medical University, 95 Yong An Road, Xicheng District, Beijing 100050, China.
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Drummond PD, Morellini N, Visser E, Finch PM. Expression of Cutaneous Beta-2 Adrenoceptors Is Similar in Patients with Complex Regional Pain Syndrome and Pain-Free Controls. PAIN MEDICINE 2020; 21:1199-1207. [PMID: 31120123 DOI: 10.1093/pm/pnz110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE Studies in rodents suggest that cutaneous beta-2 adrenoceptors (β2-ARs) mediate inflammation and pain after tissue injury and that inflammation and peripheral nerve injury trigger increases in neuronal β2-AR expression. Hence, the aim of this study was to investigate the expression of β2-ARs on keratinocytes and dermal nerves in patients with complex regional pain syndrome (CRPS). DESIGN, SETTING, AND SUBJECTS Fifty-eight patients with CRPS were recruited for this study. In addition, skin biopsies were obtained from 13 pain-free women and three pain-free men of similar age and sex distribution as the patients. METHODS Quantitative sensory tests for assessing sensitivity to pressure, pinprick, light touch, heat, and cold were administered, and skin biopsies were obtained from the affected and contralateral limbs. Skin biopsies were also obtained from a similar site on the dorsal hand or foot of pain-free controls. Immunohistochemistry and confocal microscopy were used to identify β2-ARs on keratinocytes, dermal nerves, and blood vessels in the skin samples. RESULTS The distribution of β2-ARs in keratinocytes and nerves was similar in the affected and contralateral limbs of patients and was similar for target cells in patients and controls. However, elevated β2-AR expression in reticular nerve bundles was associated with heightened sensitivity to heat pain. CONCLUSIONS These findings do not support a major role of cutaneous β2-ARs in CRPS. However, activation of neuronal β2-ARs may contribute to thermal hyperalgesia in a subgroup of patients. Whether activation of β2-ARs on keratinocytes mediates inflammation early in the course of CRPS requires further investigation.
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Affiliation(s)
- Peter D Drummond
- College of Science, Health, Engineering and Education, Murdoch University, Perth, Western Australia, Australia
| | - Natalie Morellini
- College of Science, Health, Engineering and Education, Murdoch University, Perth, Western Australia, Australia.,School of Medicine, University of Notre Dame, Fremantle, Western Australia, Australia
| | - Eric Visser
- School of Medicine, University of Notre Dame, Fremantle, Western Australia, Australia
| | - Philip M Finch
- College of Science, Health, Engineering and Education, Murdoch University, Perth, Western Australia, Australia
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Abstract
Pompe disease is a multisystemic metabolic disorder caused by a deficiency of lysosomal acid alpha-glucosidase (GAA) leading to progressive accumulation of lysosomal glycogen, lysosomal swelling and rupture in all tissues of the human body. Furthermore, autophagic buildup, organelle abnormalities, and energy deficit are regularly observed. Enzyme replacement therapy has been available for patients living with Pompe disease for more than 15 years. Although our disease knowledge has grown enormously, we still have multiple challenges to overcome. Here, I will discuss unmet clinical needs, neglected or overlooked aspects of the pathophysiology, and issues related to future therapies.
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Affiliation(s)
- Benedikt Schoser
- Friedrich-Baur-Institute at the Department of Neurology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
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Amore E, Manca ML, Ferraro M, Valenti D, La Parola V, Di Vincenzo S, Gjomarkaj M, Giammona G, Bondì ML, Pace E. Salmeterol Xinafoate (SX) loaded into mucoadhesive solid lipid microparticles for COPD treatment. Int J Pharm 2019; 562:351-358. [PMID: 30935915 DOI: 10.1016/j.ijpharm.2019.03.059] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 03/25/2019] [Accepted: 03/27/2019] [Indexed: 01/12/2023]
Abstract
Chronic obstructive pulmonary disease (COPD) is one of the main health problems worldwide. It is characterised by chronic inflammation in the lungs that leads to progressive, chronic, largely irreversible airflow obstruction. The use of long-acting β agonists remain today the frontline treatment for COPD with the aim of minimizing side effects and enhancing therapeutic usefulness. To this purpose, in this paper, mucoadhesive solid lipid microparticles (SLMs) containing a long-acting β-2 agonist, Salmeterol Xinafoate (SX) were prepared, characterised (size, z-potential, aerodynamic diameter, turbidimetric evaluations, drug loading and entrapping efficiency) and tested in a model of bronchial epithelial cells. It was demonstrated that the incorporation of SX into SLMs led to the production of particles suitable for inhalation and more efficient than the free molecule at increasing the cAMP expression in bronchial epithelial cells. In conclusion, the prepared systems, due to their aerodynamic behaviour and mucoadhesive properties, could improve the retention time of SX in the lung epithelium and its therapeutic effect, thus representing a good strategy for the treatment of COPD patients.
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Affiliation(s)
- Erika Amore
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università degli Studi di Palermo, Via Archirafi 32, 90123 Palermo, Italy; Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), U.O.S. Palermo, CNR, Via Ugo La Malfa, 153, 90146 Palermo, Italy
| | - Maria Letizia Manca
- Dipartimento Scienze della Vita e dell'Ambiente, Sezione Scienze del Farmaco, Università degli Studi di Cagliari, Via Ospedale 72, 09124 Cagliari, Italy
| | - Maria Ferraro
- Istituto di Biomedicina e Immunologia Molecolare (IBIM), CNR, Via Ugo La Malfa, 153, 90146 Palermo, Italy
| | - Donatella Valenti
- Dipartimento Scienze della Vita e dell'Ambiente, Sezione Scienze del Farmaco, Università degli Studi di Cagliari, Via Ospedale 72, 09124 Cagliari, Italy
| | - Valeria La Parola
- Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), U.O.S. Palermo, CNR, Via Ugo La Malfa, 153, 90146 Palermo, Italy
| | - Serena Di Vincenzo
- Istituto di Biomedicina e Immunologia Molecolare (IBIM), CNR, Via Ugo La Malfa, 153, 90146 Palermo, Italy
| | - Mark Gjomarkaj
- Istituto di Biomedicina e Immunologia Molecolare (IBIM), CNR, Via Ugo La Malfa, 153, 90146 Palermo, Italy
| | - Gaetano Giammona
- Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università degli Studi di Palermo, Via Archirafi 32, 90123 Palermo, Italy
| | - Maria Luisa Bondì
- Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), U.O.S. Palermo, CNR, Via Ugo La Malfa, 153, 90146 Palermo, Italy
| | - Elisabetta Pace
- Istituto di Biomedicina e Immunologia Molecolare (IBIM), CNR, Via Ugo La Malfa, 153, 90146 Palermo, Italy.
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Meller KA, Całka J, Kaczmarek M, Jana B. Expression of alpha and beta adrenergic receptors in the pig uterus during inflammation. Theriogenology 2018; 119:96-104. [PMID: 29990768 DOI: 10.1016/j.theriogenology.2018.06.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 06/13/2018] [Accepted: 06/25/2018] [Indexed: 11/18/2022]
Abstract
Under physiological conditions, noradrenaline (NA) and adrenergic receptors (ARs) are implicated in the function of the uterus. The role of NA and the expression of ARs in the inflamed uterus is not fully understood. The aim of the present study was to determine the effect of inflammation on the levels of α1 (A, B, D)-, α2 (A, B, C)- and β (1, 2, 3)-ARs mRNA and protein expression and the localization of these receptors in the porcine uterus. On Day 3 of the estrous cycle (Day 0 of the study), 50 ml of either saline (group SAL) or E. coli suspension (109 colony-forming units/ml, group E. coli) were injected into each uterine horn. In the control pigs (group CON), only laparotomy was performed. Eight days later, α1D-ARs mRNA (P < 0.001) and protein (P < 0.05) levels and α2A-ARs protein level (P < 0.05) were increased in the inflamed endometrium, while the α2C-ARs protein level (P < 0.001) was lowered, as compared to the SAL and CON groups. In the inflamed endometrium, β2-ARs mRNA (P < 0.01) and protein (CON: P < 0.01, SAL: P < 0.001) expression was lower than in the other two groups, and β1-ARs mRNA (P < 0.001) and protein (P < 0.01) expression was higher compared to the SAL group. After bacterial treatment, α2A- (P < 0.001) and α2B (P < 0.05) -ARs protein levels and β2-ARs mRNA (CON: P < 0.01, SAL: P < 0.05) and protein (CON: P < 0.01, SAL: P < 0.05) expression in myometrium were found to be increased compared to both groups. In turn, in myometrium following E. coli infusion, the α2C-ARs protein level was lower (P < 0.01) than in the CON group. All studied receptors were present in the luminal and glandular epithelium, blood vessels and myometrial muscular cells of the gilt uteri in the E. coli, SAL and CON groups. The data show that inflammation changes the ARs expression in porcine uterus, suggesting their importance in the course/consequences of uterine inflammation. Those affected ARs may constitute a therapeutic target in an inflamed uterus.
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Affiliation(s)
- K A Meller
- Division of Reproductive Biology, Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences, Tuwima 10 Str., 10-748 Olsztyn, Poland
| | - J Całka
- Division of Clinical Physiology, Faculty of Veterinary Medicine, University of Warmia and Mazury, Oczapowskiego 14 Str., 11-041 Olsztyn, Poland
| | - M Kaczmarek
- Division of Reproductive Biology, Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences, Tuwima 10 Str., 10-748 Olsztyn, Poland
| | - B Jana
- Division of Reproductive Biology, Institute of Animal Reproduction and Food Research of the Polish Academy of Sciences, Tuwima 10 Str., 10-748 Olsztyn, Poland.
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Matera MG, Page C, Rinaldi B. β2-Adrenoceptor signalling bias in asthma and COPD and the potential impact on the comorbidities associated with these diseases. Curr Opin Pharmacol 2018; 40:142-146. [PMID: 29763833 DOI: 10.1016/j.coph.2018.04.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 04/09/2018] [Accepted: 04/20/2018] [Indexed: 10/16/2022]
Abstract
Inhaled selective β2-agonists are the most widely used treatment for obstructive airway diseases. The classical mechanism of action of these drugs is considered as their ability to activate β2-adrenergic receptors (β2-AR) on airway smooth muscle leading to G-protein activation and subsequent generation of c-AMP causing bronchodilation. However, there is now growing evidence to suggest that binding of β2-agonists to β2-AR is pleotropically coupled to many intracellular pathways whereby depending on the state of the β2-AR when activated, a subset of different intracellular responses can be triggered. This is called biased agonism (or functional selectivity) and this type of activity has now been observed with different types of G protein-coupled receptor (GPCR), not just β2-AR. Accordingly, drug efficacy for many agonists binding to GPCRs can no longer be solely described in terms of a single relationship between binding of a ligand to a receptor and the subsequent magnitude of the cellular response, but is often far more complex reflecting a specific complement of signals following binding of a ligand to its receptor. These differences in responses depending on what state the receptor is in when the ligand binds to it can subsequently influence the intracellular signalling that in turn can influence the efficacy of β2-AR ligands. Such findings suggest that in the future it may be possible to develop new synthetic β2-agonists that could preferentially confine their activity in stabilizing/activating the receptor to a certain conformation which could lead to improved drugs either to reduce adverse responses or to avoid drugs that activate certain conformations of the receptors that may lead to tolerance or desensitization following repeated activation.
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Affiliation(s)
- Maria Gabriella Matera
- Department of Experimental Medicine, University of Campania Luigi Vanvitelli, Naples, Italy
| | - Clive Page
- Sackler Institute of Pulmonary Pharmacology, Institute of Pharmaceutical Science, King's College London, London, UK
| | - Barbara Rinaldi
- Department of Experimental Medicine, University of Campania Luigi Vanvitelli, Naples, Italy.
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Tan DWS, Wong JL, Tie ST, Abisheganaden JA, Lim AYH, Wong WSF. β 2-adrenoceptor in obstructive airway diseases: Agonism, antagonism or both? World J Respirol 2015; 5:199-206. [DOI: 10.5320/wjr.v5.i3.199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 08/27/2015] [Accepted: 10/08/2015] [Indexed: 02/06/2023] Open
Abstract
Obstructive airway disease is a complex disease entity including several maladies characterized by bronchoconstriction and abnormal airway inflammation. Reversing bronchoconstriction leads to symptomatic relief and improvement in quality of life, both in reversible (bronchial asthma) and partially reversible (chronic obstructive airway disease) obstructive airway diseases. β2-adrenoceptor expressed in human airway is the main β-receptor subtype, and its activation in airway smooth muscle cells leads to bronchodilatation. Drugs targeting β-adrenoceptors have been around for many years, for which agonists of the receptors are used in bronchodilation while antagonists are used in cardiovascular diseases. This review article summarizes the effect and usage of β2-agonist in obstructive airway disease, addressing the benefits and potential risks of β2-agonist. The article also looks at the safety of β-blocker usage for cardiovascular disease in patients with obstructive airway disease. There is also emerging evidence that non-selective β-blockers with inverse agonism ironically can have long-term beneficial effects in obstructive airway disease that is beyond cardiovascular protection. Further trials are urgently needed in this area as it might lead to a dramatic turnaround in clinical practice for obstructive airway diseases as has already been seen in the usage of β-blockers for heart failure.
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El-Zohairy S, Oriowo M, Ezeamuzie C. Cyclic Adenosine Monophosphate-Mediated Enhancement of Vascular Endothelial Growth Factor Released by Differentiated Human Monocytic Cells: The Role of Protein Kinase A. Med Princ Pract 2015; 24:548-54. [PMID: 26139101 PMCID: PMC5588270 DOI: 10.1159/000433540] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/24/2015] [Indexed: 01/19/2023] Open
Abstract
OBJECTIVE Our investigation was designed to examine the signaling pathway involved in the enhancement of vascular endothelial growth factor (VEGF) release by β-adrenoceptor agonists. MATERIALS AND METHODS Human U937 cells differentiated into macrophages were primed with lipopolysaccharide (LPS) in the absence or presence of β-adrenoceptor agonists and antagonists. The VEGF released and the intracellular cyclic adenosine monophosphate (cAMP) generated were assayed by ELISA. Where necessary, differences between mean values were tested for significance using Student's t test. RESULTS Isoprenaline, procaterol and salbutamol concentration-dependently enhanced the release of VEGF induced by LPS in U937 cells. R*,R*-(±)-4-[2-[(2-(3-chlorophenyl)-2-hydroxyethyl)amino]propyl]phenoxyacetic acid (BRL 37344), a selective β3-adrenoceptor agonist, did not enhance VEGF release. Using isoprenaline as an agonist, propranolol, ICI 118551 and atenolol produced a parallel rightward shift of the concentration-response curve with no reduction in the maximum response. The -logKB values were 8.12 ± 0.17, 8.03 ± 0.05 and 7.23 ± 0.05 for propranolol, ICI 118551 and atenolol, respectively, indicating the possible involvement of both β1- and β2-adrenoceptor subtypes. Isoprenaline and prostaglandin E2 concentration-dependently increased cAMP generation in U937 cells. Isoprenaline, db-cAMP and 6-Bnz-cAMP, a protein kinase A (PKA) activator, all enhanced VEGF release induced by LPS, and this effect was abolished by KT 5720 and Rp-cAMPS, which are both selective PKA inhibitors, suggesting that PKA is the downstream effector of cAMP activity. 8-CPT-cAMP, a selective activator of the Epac system, had no effect on VEGF release induced by LPS, indicating that the Epac pathway played no role in the release process. CONCLUSION In this study, we established that β1- and β2- but not β3-adrenoceptors mediated cAMP-dependent enhancement of VEGF release induced by LPS in differentiated U937 cells, and that PKA was the downstream effector of cAMP activity.
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Affiliation(s)
| | - M.A. Oriowo
- *Prof. M.A. Oriowo, Department of Pharmacology and Toxicology, Faculty of Medicine, Health Sciences Centre, Kuwait University, PO Box 24923, Safat 13110 (Kuwait), E-Mail
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