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Kaczor A, Knutelska J, Kucwaj-Brysz K, Zygmunt M, Żesławska E, Siwek A, Bednarski M, Podlewska S, Jastrzębska-Więsek M, Nitek W, Sapa J, Handzlik J. The Subtype Selectivity in Search of Potent Hypotensive Agents among 5,5-Dimethylhydantoin Derived α 1-Adrenoceptors Antagonists. Int J Mol Sci 2023; 24:16609. [PMID: 38068933 PMCID: PMC10706087 DOI: 10.3390/ijms242316609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 11/18/2023] [Accepted: 11/19/2023] [Indexed: 12/18/2023] Open
Abstract
In order to find new hypotensive drugs possessing higher activity and better selectivity, a new series of fifteen 5,5-dimethylhydantoin derivatives (1-15) was designed. Three-step syntheses, consisting of N-alkylations using standard procedures as well as microwaves, were carried out. Crystal structures were determined for compounds 7-9. All of the synthesized 5,5-dimethylhydantoins were tested for their affinity to α1-adrenergic receptors (α1-AR) using both in vitro and in silico methods. Most of them displayed higher affinity (Ki < 127.9 nM) to α1-adrenoceptor than urapidil in radioligand binding assay. Docking to two subtypes of adrenergic receptors, α1A and α1B, was conducted. Selected compounds were tested for their activity towards two α1-AR subtypes. All of them showed intrinsic antagonistic activity. Moreover, for two compounds (1 and 5), which possess o-methoxyphenylpiperazine fragments, strong activity (IC50 < 100 nM) was observed. Some representatives (3 and 5), which contain alkyl linker, proved selectivity towards α1A-AR, while two compounds with 2-hydroxypropyl linker (11 and 13) to α1B-AR. Finally, hypotensive activity was examined in rats. The most active compound (5) proved not only a lower effective dose than urapidil but also a stronger effect than prazosin.
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Affiliation(s)
- Aneta Kaczor
- Department of Technology and Biotechnology of Drugs, Medical College, Jagiellonian University, Medyczna 9, 30-688 Krakow, Poland; (A.K.); (K.K.-B.)
| | - Joanna Knutelska
- Department of Pharmacodynamics, Medical College, Jagiellonian University, Medyczna 9, 30-688 Krakow, Poland; (J.K.); (M.Z.); (M.B.); (J.S.)
| | - Katarzyna Kucwaj-Brysz
- Department of Technology and Biotechnology of Drugs, Medical College, Jagiellonian University, Medyczna 9, 30-688 Krakow, Poland; (A.K.); (K.K.-B.)
| | - Małgorzata Zygmunt
- Department of Pharmacodynamics, Medical College, Jagiellonian University, Medyczna 9, 30-688 Krakow, Poland; (J.K.); (M.Z.); (M.B.); (J.S.)
| | - Ewa Żesławska
- Institute of Biology and Earth Sciences, University of the National Education Commision, Podchorążych 2, 30-084 Krakow, Poland;
| | - Agata Siwek
- Department of Pharmacobiology, Medical College, Jagiellonian University, Medyczna 9, 30-688 Krakow, Poland;
| | - Marek Bednarski
- Department of Pharmacodynamics, Medical College, Jagiellonian University, Medyczna 9, 30-688 Krakow, Poland; (J.K.); (M.Z.); (M.B.); (J.S.)
| | - Sabina Podlewska
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Medicinal Chemistry, Smętna 12, 31-343 Krakow, Poland;
| | | | - Wojciech Nitek
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland;
| | - Jacek Sapa
- Department of Pharmacodynamics, Medical College, Jagiellonian University, Medyczna 9, 30-688 Krakow, Poland; (J.K.); (M.Z.); (M.B.); (J.S.)
| | - Jadwiga Handzlik
- Department of Technology and Biotechnology of Drugs, Medical College, Jagiellonian University, Medyczna 9, 30-688 Krakow, Poland; (A.K.); (K.K.-B.)
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Hu S, Huang R, Keller P, Götz M, Tamalunas A, Weinhold P, Waidelich R, Stief CG, Hennenberg M. Selective inhibition of neurogenic, but not agonist-induced contractions by phospholipase A 2 inhibitors points to presynaptic phospholipase A 2 functions in contractile neurotransmission to human prostate smooth muscle. Neurourol Urodyn 2023; 42:1522-1531. [PMID: 37583250 DOI: 10.1002/nau.25242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/28/2023] [Accepted: 06/29/2023] [Indexed: 08/17/2023]
Abstract
BACKGROUND Phospholipases A2 (PLA2 ) may be involved in α1 -adrenergic contraction by formation of thromboxane A2 in different smooth muscle types. However, whether this mechanism occurs with α1 -adrenergic contractions of the prostate, is still unknown. While α1 -adrenoceptor antagonists are the first line option for medical treatment of voiding symptoms in benign prostatic hyperplasia (BPH), improvements are limited, probably by nonadrenergic contractions including thromboxane A2 . Here, we examined effects of PLA2 inhibitors on contractions of human prostate tissues. METHODS Prostate tissues were obtained from radical prostatectomy. Contractions were induced by electric field stimulation (EFS) and by α1 -adrenergic agonists in an organ bath, after application of the cytosolic PLA2 inhibitors ASB14780 and AACOCF3, the secretory PLA2 inhibitor YM26734, the leukotriene receptor antagonist montelukast, or of solvent to controls. RESULTS Frequency-dependent contractions of human prostate tissues induced by EFS were inhibited by 25% at 8 Hz, 38% at 16 Hz and 37% at 32 Hz by ASB14780 (1 µM), and by 32% at 16 Hz and 22% at 32 Hz by AACOCF3 (10 µM). None of both inhibitors affected contractions induced by noradrenaline, phenylephrine or methoxamine. YM26734 (3 µM) and montelukast (0.3 and 1 µM) neither affected EFS-induced contractions, nor contractions by α1 -adrenergic agonists, while all contractions were substantially inhibited by silodosin (100 nM). CONCLUSIONS Our findings suggest presynaptic PLA2 functions in prostate smooth muscle contraction, while contractions induced by α1 -adrenergic agonists occur PLA2 -independent. Lacking sensitivity to montelukast excludes an involvement of PLA2 -derived leukotrienes in promotion of contractile neurotransmission.
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Affiliation(s)
- Sheng Hu
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Ru Huang
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Patrick Keller
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Melanie Götz
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | | | - Philipp Weinhold
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | | | - Christian G Stief
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Martin Hennenberg
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
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Sung DJ, Park S, Noh HJ, Golpasandi S, Eun SH, Lee H, Kim B, Wie J, Seo MS, Park SW, Bae YM. Receptor-specific contributions of caveolae, PKC, and Src tyrosine kinase to serotonergic and adrenergic regulation of Kv channels and vasoconstriction. Life Sci 2023:121903. [PMID: 37394095 DOI: 10.1016/j.lfs.2023.121903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/28/2023] [Accepted: 06/28/2023] [Indexed: 07/04/2023]
Abstract
AIMS Caveolae are invaginated, Ω-shaped membrane structures. They are now recognized as portals for signal transduction of multiple chemical and mechanical stimuli. Notably, the contribution of caveolae has been reported to be receptor-specific. However, details of how they differentially contribute to receptor signaling remain unclear. MAIN METHODS Using isometric tension measurements, patch-clamping, and western blotting, we examined the contribution of caveolae and their related signaling pathways to serotonergic (5-HT2A receptor-mediated) and adrenergic (α1-adrenoceptor-mediated) signaling in rat mesenteric arteries. KEY FINDINGS Disruption of caveolae by methyl-β-cyclodextrin effectively blocked vasoconstriction mediated by the 5-HT2A receptor (5-HT2AR), but not by the α1-adrenoceptor. Caveolar disruption selectively impaired 5-HT2AR-mediated voltage-dependent K+ channel (Kv) inhibition, but not α1-adrenoceptor-mediated Kv inhibition. In contrast, both serotonergic and α1-adrenergic effects on vasoconstriction, as well as Kv currents, were similarly blocked by the Src tyrosine kinase inhibitor PP2. However, inhibition of protein kinase C (PKC) by either GO6976 or chelerythrine selectively attenuated the effects mediated by the α1-adrenoceptor, but not by 5-HT2AR. Disruption of caveolae decreased 5-HT2AR-mediated Src phosphorylation, but not α1-adrenoceptor-mediated Src phosphorylation. Finally, the PKC inhibitor GO6976 blocked Src phosphorylation by the α1-adrenoceptor, but not by 5-HT2AR. SIGNIFICANCE 5-HT2AR-mediated Kv inhibition and vasoconstriction are dependent on caveolar integrity and Src tyrosine kinase, but not on PKC. In contrast, α1-adrenoceptor-mediated Kv inhibition and vasoconstriction are not dependent on caveolar integrity, but rather on PKC and Src tyrosine kinase. Caveolae-independent PKC is upstream of Src activation for α1-adrenoceptor-mediated Kv inhibition and vasoconstriction.
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Affiliation(s)
- Dong Jun Sung
- Department of Sport and Health Studies, College of Biomedical and Health Science, Konkuk University, Chungju 27478, Republic of Korea; Sports Convergence Institute, Konkuk University, Chungju 27478, Republic of Korea; Center for Metabolic Diseases, Konkuk University, Chungju 27478, Republic of Korea; Research Institute for Biomedical & Health Science, Chungju 27478, Republic of Korea
| | - Solah Park
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Republic of Korea
| | - Hyun Ju Noh
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Republic of Korea
| | - Shadi Golpasandi
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Republic of Korea
| | - Seo Hyeon Eun
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Republic of Korea
| | - Hyeryeong Lee
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Republic of Korea
| | - Bokyung Kim
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Republic of Korea
| | - Jinhong Wie
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Republic of Korea
| | - Mi Seon Seo
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Republic of Korea
| | - Sang Woong Park
- Department of Emergency Medical Services, Eulji University, Seongnam 13135, Republic of Korea.
| | - Young Min Bae
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Republic of Korea.
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Tusubira D, Munezero J, Agu PC, Ajayi CO, Oloro J, Namale N, Ssedyabane F, Nakiguli CK, Adegboyega AE, Aja PM. In-vivo and in-silico studies revealed the molecular mechanisms of Colocasia esculenta phenolics as novel chemotherapy against benign prostatic hyperplasia via inhibition of 5α-reductase and α1-adrenoceptor. In Silico Pharmacol 2023; 11:4. [PMID: 36873908 PMCID: PMC9978050 DOI: 10.1007/s40203-023-00141-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 02/11/2023] [Indexed: 03/05/2023] Open
Abstract
Benign Prostatic Hyperplasia (BPH) is a major cause of lower urinary tract infections and erectile dysfunction thus a major contributor to lowering the quality of life among older men. In this study, we investigated the molecular mechanism of Colocasia esculenta (CE) as a novel agent for BPH chemotherapy. In vivo, we assigned 45 male Wistar albino rats about 6 weeks old into 9 experimental groups (n = 5). BPH was induced in groups 2-9 with 3 mg/kg of Testosterone Propionate (TP) subcutaneously. Group 2 (BPH) was not treated. Group 3 was treated with 5 mg/kg Finasteride (standard drug). Group 4-9 were treated each with 200 mg/kg body weight (b.w) of CE crude tuber extracts/fractions (ethanol, hexane, dichloromethane, ethyl acetate, butanol, aqueous). At the end of treatment, we sampled the rats' serum to check the level of PSA. In silico, we conducted a molecular docking of the crude extract of CE phenolics (CyP) previously reported, targeting 5α-Reductase and α1-Adrenoceptor linked to the BPH progressions. We adopted the standard inhibitors/antagonists (5α-reductase: finasteride; α1-adrenoceptor: tamsulosin) of the target proteins as controls. Furthermore, the pharmacological properties of the lead molecules were studied in terms of ADMET using swissadme and pKCSM resources, respectively. Results showed that administration of TP in male Wistar albino rats significantly (p < 0.05) elevated serum PSA levels whereas CE crude extracts/fractions significantly (p < 0.05) lowered the serum PSA level. Also, fourteen of the CyPs bind to at least one or two of the target proteins with their binding affinity of between - 9.3 to - 5.6 kcal/mol and - 6.9 to - 4.2 kcal/mol, respectively. The CyPs possess better pharmacological properties compared to the standard drugs. Therefore, they have the potentials to be enlisted for clinical trials towards the management of BPH. Graphical Abstract
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Affiliation(s)
- Deusdedit Tusubira
- Biochemistry Department, Faculty of Medicine, Mbarara University of Science and Technology, P. O. Box 1410, Mbarara, Uganda
- Mbarara University of Science and Technology, Biochemistry Department, Mbarara, Uganda
| | - Jonasi Munezero
- Biochemistry Department, Faculty of Medicine, Mbarara University of Science and Technology, P. O. Box 1410, Mbarara, Uganda
| | - Peter Chinedu Agu
- Department of Biochemistry, Faculty of Science, Ebonyi State University, PMB 053, Abakaliki, Nigeria
| | | | - Joseph Oloro
- Department of Pharmacology and Therapeutics, Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Nathiim Namale
- Biochemistry Department, Faculty of Medicine, Mbarara University of Science and Technology, P. O. Box 1410, Mbarara, Uganda
| | - Frank Ssedyabane
- Medical Laboratory Science, Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Caroline Kiwanuka Nakiguli
- Department of Chemistry, Faculty of Science, Mbarara University of Science and Technology, Mbarara, Uganda
| | | | - Patrick Maduabuchi Aja
- Biochemistry Department, Faculty of Medicine, Mbarara University of Science and Technology, P. O. Box 1410, Mbarara, Uganda
- Department of Biochemistry, Faculty of Science, Ebonyi State University, PMB 053, Abakaliki, Nigeria
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5
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Lim I, Chess-Williams R. Mirabegron attenuates porcine ureteral contractility via α1-adrenoceptor antagonism. Naunyn Schmiedebergs Arch Pharmacol 2022; 395:839-847. [PMID: 35445849 PMCID: PMC9192402 DOI: 10.1007/s00210-022-02244-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 04/13/2022] [Indexed: 11/30/2022]
Abstract
The β3-agonist mirabegron is thought to induce relaxation of the detrusor muscle, contributing to the improvement of overactive bladder symptoms. There has been recent interest in purposing mirabegron as a medical expulsive therapy drug to improve the passage of smaller kidney stones by relaxing the ureteral smooth muscles. The aim of this study was to determine the effects of mirabegron on the activity of the ureter. Additionally, we investigated the receptor and mechanisms through which mirabegron exerts these effects. In vitro agonist-induced responses of isolated porcine distal ureteral tissues were measured in the absence and presence of mirabegron in organ bath experiments. The responses were expressed as frequency, area under the curve and maximum amplitude. Mirabegron at concentrations of 100 nM and lower failed to suppress phenylephrine- or 5-HT-induced contractions in the porcine ureteral strip. Mirabegron at 1 μM and 10 μM produced a rightward shift of phenylephrine concentration–response curves in these tissues. This effect of mirabegron (10 μM) was not present in 5-HT concentration–response curves. The mirabegron effect on phenylephrine-induced contractions was also not abolished by β-adrenoceptor antagonist SR 59230A (10 μM), β-adrenoceptor antagonist propranolol (10 μM), α2-adrenoceptor antagonist yohimbine (30 nM), and nitric oxide synthase inhibitor l-NNA (10 μM). The present results show that mirabegron suppresses ureteral contractile responses in the porcine ureter via α1-adrenoceptor antagonism, since their effects were not present when the tissues were contracted with 5-HT. Furthermore, the inhibitory effects by mirabegron were not affected by β3-adrenoceptor antagonists.
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Affiliation(s)
- Iris Lim
- Centre for Urology Research, Faculty of Health Science & Medicine, Bond University, Robina, QLD, 4229, Australia.
| | - Russ Chess-Williams
- Centre for Urology Research, Faculty of Health Science & Medicine, Bond University, Robina, QLD, 4229, Australia
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Zreik F, Meshulam R, Shichel I, Webb M, Shibolet O, Jacob G. Effect of ingesting a meal and orthostasis on the regulation of splanchnic and systemic hemodynamics and the responsiveness of cardiovascular α 1-adrenoceptors. Am J Physiol Gastrointest Liver Physiol 2021; 321:G513-G526. [PMID: 34523347 DOI: 10.1152/ajpgi.00142.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Postprandial orthostasis activates mechanisms of cardiovascular homeostasis to maintain normal blood pressure (BP) and adequate blood flow to vital organs. The underlying mechanisms of cardiovascular homeostasis in postprandial orthostasis still require elucidation. Fourteen healthy volunteers were recruited to investigate the effect of an orthostatic challenge (60°-head-up-tilt for 20 min) on splanchnic and systemic hemodynamics before and after ingesting an 800-kcal composite meal. The splanchnic circulation was assessed by ultrasonography of the superior mesenteric and hepatic arteries and portal vein. Systemic hemodynamics were assessed noninvasively by continuous monitoring of BP, heart rate (HR), cardiac output (CO), and the pressor response to an intravenous infusion on increasing doses of phenylephrine, an α1-adrenoceptor agonist. Neurohumoral regulation was assessed by spectral analysis of HR and BP, plasma catecholamine and aldosterone levels and plasma renin activity. Postprandial mesenteric hyperemia was associated with an increase in CO, a decrease in SVR and cardiac vagal tone, and reduction in baroreflex sensitivity with no change in sympathetic tone. Arterial α1-adrenoceptor responsiveness was preserved and reduced in hepatic sinusoids. Postprandial orthostasis was associated with a shift of 500 mL of blood from mesenteric to systemic circulation with preserved sympathetic-mediated vasoconstriction. Meal ingestion provokes cardiovascular hyperdynamism, cardiac vagolysis, and resetting of the baroreflex without activation of the sympathetic nervous system. Meal ingestion also alters α1-adrenoceptor responsiveness in the hepatic sinusoids and participates in the redistribution of blood volume from the mesenteric to the systemic circulation to maintain a normal BP during orthostasis.NEW & NOTEWORTHY A unique integrated investigation on the effect of meal on neurohumoral mechanisms and blood flow redistribution of the mesenteric circulation during orthostasis was investigated. Food ingestion results in cardiovascular hyperdynamism, reduction in cardiac vagal tone, and baroreflex sensitivity and causes a decrease in α1-adrenoceptor responsiveness only in the venous intrahepatic sinusoids. About 500-mL blood shifts from the mesenteric to the systemic circulation during orthostasis. Accordingly, the orthostatic homeostatic mechanisms are better understood.
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Affiliation(s)
- Farid Zreik
- Department of Medicine, F and J. Recanati Autonomic Dysfunction Center, Tel Aviv "Sourasky" Medical Center, Tel Aviv, Israel
| | - Reshef Meshulam
- Department of Medicine, F and J. Recanati Autonomic Dysfunction Center, Tel Aviv "Sourasky" Medical Center, Tel Aviv, Israel
| | - Ido Shichel
- Department of Medicine, F and J. Recanati Autonomic Dysfunction Center, Tel Aviv "Sourasky" Medical Center, Tel Aviv, Israel
| | - Muriel Webb
- Department of Gastroenterology at Tel Aviv "Sourasky" Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Oren Shibolet
- Department of Gastroenterology at Tel Aviv "Sourasky" Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Giris Jacob
- Department of Medicine, F and J. Recanati Autonomic Dysfunction Center, Tel Aviv "Sourasky" Medical Center, Tel Aviv, Israel
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Lustyk K, Sałaciak K, Zaręba P, Siwek A, Sapa J, Pytka K. The Antiarrhythmic Activity of Novel Pyrrolidin-2-one Derivative S-75 in Adrenaline-Induced Arrhythmia. Pharmaceuticals (Basel) 2021; 14:1065. [PMID: 34832847 DOI: 10.3390/ph14111065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/13/2021] [Accepted: 10/14/2021] [Indexed: 11/29/2022] Open
Abstract
Arrhythmia is a quivering or irregular heartbeat that can often lead to blood clots, stroke, heart failure, and other heart-related complications. The limited efficacy and safety of antiarrhythmic drugs require the design of new compounds. Previous research indicated that pyrrolidin-2-one derivatives possess an affinity for α1-adrenergic receptors. The blockade of α1-adrenoceptor may play a role in restoring normal sinus rhythm; therefore, we aimed to verify the antiarrhythmic activity of novel pyrrolidin-2-one derivative S-75. In this study, we assessed the influence on sodium, calcium, potassium channels, and β1-adrenergic receptors to investigate the mechanism of action of S-75. Lack of affinity for β1-adrenoceptors and weak effects on ion channels decreased the role of these adrenoceptors and channels in the pharmacological activity of S-75. Next, we evaluated the influence of S-75 on normal ECG in rats and isolated rat hearts, and the tested derivative did not prolong the QTc interval, which may confirm the lack of the proarrhythmic potential. We tested antiarrhythmic activity in adrenaline-, aconitine- and calcium chloride-induced arrhythmia models in rats. The studied compound showed prophylactic antiarrhythmic activity in the adrenaline-induced arrhythmia, but no significant activity in the model of aconitine- or calcium chloride-induced arrhythmia. In addition, S-75 was not active in the model of post-reperfusion arrhythmias of the isolated rat hearts. Conversely, the compound showed therapeutic antiarrhythmic properties in adrenaline-induced arrhythmia, reducing post-arrhythmogen heart rhythm disorders, and decreasing animal mortality. Thus, we suggest that the blockade of α1-adrenoceptor might be beneficial in restoring normal heart rhythm in adrenaline-induced arrhythmia.
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Uta D, Hattori T, Yoshimura M. Analyses of the Mode of Action of an Alpha-Adrenoceptor Blocker in Substantia Gelatinosa Neurons in Rats. Int J Mol Sci 2021; 22:9636. [PMID: 34502543 PMCID: PMC8431806 DOI: 10.3390/ijms22179636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/24/2021] [Accepted: 09/03/2021] [Indexed: 11/17/2022] Open
Abstract
To elucidate why naftopidil increases the frequency of spontaneous synaptic currents in only some substantia gelatinosa (SG) neurons, post-hoc analyses were performed. Blind patch-clamp recording was performed using slice preparations of SG neurons from the spinal cords of adult rats. Spontaneous inhibitory and excitatory postsynaptic currents (sIPSCs and sEPSCs, respectively) were recorded. The ratios of the frequency and amplitude of the sIPSCs and sEPSCs following the introduction of naftopidil compared with baseline, and after the application of naftopidil, serotonin (5-HT), and prazosin, compared with noradrenaline (NA) were evaluated. First, the sIPSC analysis indicated that SG neurons reached their full response ratio for NA at 50 μM. Second, they responded to 5-HT (50 μM) with a response ratio similar to that for NA, but prazosin (10 μM) did not change the sEPSCs and sIPSCs. Third, the highest concentration of naftopidil (100 μM) led to two types of response in the SG neurons, which corresponded with the reactions to 5-HT and prazosin. These results indicate that not all neurons were necessarily activated by naftopidil, and that the micturition reflex may be regulated in a sophisticated manner by inhibitory mechanisms in these interneurons.
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Affiliation(s)
- Daisuke Uta
- Department of Applied Pharmacology, Faculty of Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
| | - Tsuyoshi Hattori
- Department of Medical Affairs, Asahi Kasei Pharma Corporation, Tokyo 100-0006, Japan
| | - Megumu Yoshimura
- Department of Orthopedic Surgery, Nakamura Hospital, Fukuoka 822-0002, Japan;
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9
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Huang R, Liu Y, Ciotkowska A, Tamalunas A, Waidelich R, Strittmatter F, Stief CG, Hennenberg M. Concentration-dependent alpha 1-Adrenoceptor Antagonism and Inhibition of Neurogenic Smooth Muscle Contraction by Mirabegron in the Human Prostate. Front Pharmacol 2021; 12:666047. [PMID: 34248624 PMCID: PMC8264149 DOI: 10.3389/fphar.2021.666047] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 06/08/2021] [Indexed: 01/25/2023] Open
Abstract
Introduction: Mirabegron is available for treatment of storage symptoms in overactive bladder, which may be improved by β3-adrenoceptor-induced bladder smooth muscle relaxation. In addition to storage symptoms, lower urinary tract symptoms in men include obstructive symptoms attributed to benign prostatic hyperplasia, caused by increased prostate smooth muscle tone and prostate enlargement. In contrast to the bladder and storage symptoms, effects of mirabegron on prostate smooth muscle contraction and obstructive symptoms are poorly understood. Evidence from non-human smooth muscle suggested antagonism of α1-adrenoceptors as an important off-target effect of mirabegron. As α1-adrenergic contraction is crucial in pathophysiology and medical treatment of obstructive symptoms, we here examined effects of mirabegron on contractions of human prostate tissues and on proliferation of prostate stromal cells. Methods: Contractions were induced in an organ bath. Effects of mirabegron on proliferation, viability, and cAMP levels in cultured stromal cells were examined by EdU assays, CCK-8 assays and enzyme-linked immunosorbent assay. Results: Mirabegron in concentrations of 5 and 10 μM, but not 1 µM inhibited electric field stimulation-induced contractions of human prostate tissues. Mirabegron in concentrations of 5 and 10 µM shifted concentration response curves for noradrenaline-, methoxamine- and phenylephrine-induced contractions to the right, including recovery of contractions at high concentrations of α1-adrenergic agonists, increased EC50 values, but unchanged Emax values. Rightshifts of noradrenaline concentration response curves and inhibition of EFS-induced contractions were resistant to L-748,337, l-NAME, and BPIPP. 1 µM mirabegron was without effect on α1-adrenergic contractions. Endothelin-1- and U46619-induced contractions were not affected or only inhibited to neglectable extent. Effects of mirabegron (0.5–10 µM) on proliferation and viability of stromal cells were neglectable or small, reaching maximum decreases of 8% in proliferation assays and 17% in viability assays. Mirabegron did not induce detectable increases of cAMP levels in cultured stromal cells. Conclusion: Mirabegron inhibits neurogenic and α1-adrenergic human prostate smooth muscle contractions. This inhibition may be based on antagonism of α1-adrenoceptors by mirabegron, and does not include activation of β3-adrenoceptors and requires concentrations ranging 50-100fold higher than plasma concentrations reported from normal dosing. Non-adrenergic contractions and proliferation of prostate stromal cells are not inhibited by mirabegron.
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Affiliation(s)
- Ru Huang
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Yuhan Liu
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Anna Ciotkowska
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | | | | | | | - Christian G Stief
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
| | - Martin Hennenberg
- Department of Urology, University Hospital, LMU Munich, Munich, Germany
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10
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Cayupe B, Morgan C, Puentes G, Valladares L, Burgos H, Castillo A, Hernández A, Constandil L, Ríos M, Sáez-Briones P, Barra R. Hypertension in Prenatally Undernourished Young-Adult Rats Is Maintained by Tonic Reciprocal Paraventricular-Coerulear Excitatory Interactions. Molecules 2021; 26:3568. [PMID: 34207980 DOI: 10.3390/molecules26123568] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/19/2021] [Accepted: 05/31/2021] [Indexed: 11/17/2022] Open
Abstract
Prenatally malnourished rats develop hypertension in adulthood, in part through increased α1-adrenoceptor-mediated outflow from the paraventricular nucleus (PVN) to the sympathetic system. We studied whether both α1-adrenoceptor-mediated noradrenergic excitatory pathways from the locus coeruleus (LC) to the PVN and their reciprocal excitatory CRFergic connections contribute to prenatal undernutrition-induced hypertension. For that purpose, we microinjected either α1-adrenoceptor or CRH receptor agonists and/or antagonists in the PVN or the LC, respectively. We also determined the α1-adrenoceptor density in whole hypothalamus and the expression levels of α1A-adrenoceptor mRNA in the PVN. The results showed that: (i) agonists microinjection increased systolic blood pressure and heart rate in normotensive eutrophic rats, but not in prenatally malnourished subjects; (ii) antagonists microinjection reduced hypertension and tachycardia in undernourished rats, but not in eutrophic controls; (iii) in undernourished animals, antagonist administration to one nuclei allowed the agonists recover full efficacy in the complementary nucleus, inducing hypertension and tachycardia; (iv) early undernutrition did not modify the number of α1-adrenoceptor binding sites in hypothalamus, but reduced the number of cells expressing α1A-adrenoceptor mRNA in the PVN. These results support the hypothesis that systolic pressure and heart rate are increased by tonic reciprocal paraventricular-coerulear excitatory interactions in prenatally undernourished young-adult rats.
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11
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Lim I, Sellers DJ, Chess-Williams R. Current and emerging pharmacological targets for medical expulsive therapy. Basic Clin Pharmacol Toxicol 2021; 130 Suppl 1:16-22. [PMID: 33991399 DOI: 10.1111/bcpt.13613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/04/2021] [Accepted: 05/08/2021] [Indexed: 11/28/2022]
Abstract
The primary goals of medical expulsive therapy are to increase the rate of stone expulsion along the ureter to avoid ureteral obstruction and reduce ureteral colic and thus avoid the need for surgical and more invasive interventions. This review focussed on the findings from in vivo and in vitro animal and human studies that have investigated the pharmacological mechanisms controlling ureteral motility and their translation to current and potentially new clinically used drugs for increasing the rate of stone expulsion along the ureter. The complicated contractility profile of the ureter, which alters with age, tissue segment region, orientation and species contributes to the difficulty of interpreting studies on ureteral pharmacology, which translates to the complexity of discovering ideal drug targets for medical expulsive therapy. Nevertheless, the current drug classes clinically used for patients with stone lodgement include α1 -adrenoceptor antagonists, calcium channel blockers and NSAIDS, whilst there are promising targets for drug development that require further clinical investigations including the phosphodiesterase type 5 enzyme, β-adrenoceptors and 5-HT receptors.
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Affiliation(s)
- Iris Lim
- Centre for Urology Research, Faculty of Health Science & Medicine, Bond University, Gold Coast, QLD, Australia
| | - Donna J Sellers
- Centre for Urology Research, Faculty of Health Science & Medicine, Bond University, Gold Coast, QLD, Australia
| | - Russ Chess-Williams
- Centre for Urology Research, Faculty of Health Science & Medicine, Bond University, Gold Coast, QLD, Australia
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12
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Franzen KF, Meusel M, Engel J, Röcker T, Drömann D, Sayk F. Differential Effects of Angiotensin-II Compared to Phenylephrine on Arterial Stiffness and Hemodynamics: A Placebo-Controlled Study in Healthy Humans. Cells 2021; 10:1108. [PMID: 34062957 DOI: 10.3390/cells10051108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 04/01/2021] [Accepted: 04/09/2021] [Indexed: 11/17/2022] Open
Abstract
The α1-adrenoceptor agonist phenylephrine (PE) and Angiotensin II (Ang II) are both potent vasoconstrictors at peripheral resistance arteries. PE has pure vasoconstrictive properties. Ang II, additionally, modulates central nervous blood pressure (BP) control via sympathetic baroreflex resetting. However, it is unknown whether Ang II vs. PE mediated vasoconstriction at equipressor dose uniformly or specifically modifies arterial stiffness. We conducted a three-arm randomized placebo-controlled cross-over trial in 30 healthy volunteers (15 female) investigating the effects of Ang II compared to PE at equal systolic pressor dose on pulse wave velocity (PWV), pulse wave reflection (augmentation index normalized to heart rate 75/min, AIx) and non-invasive hemodynamics by Mobil-O-Graph™ and circulating core markers of endothelial (dys-)function. PE but not Ang II-mediated hypertension induced a strong reflex-decrease in cardiac output. Increases in PWV, AIx, total peripheral resistance and pulse pressure, in contrast, were stronger during PE compared to Ang II at equal mean aortic BP. This was accompanied by minute changes in circulating markers of endothelial function. Moreover, we observed differential hemodynamic changes after stopping either vasoactive infusion. Ang II- and PE-mediated BP increase specifically modifies arterial stiffness and hemodynamics with aftereffects lasting beyond mere vasoconstriction. This appears attributable in part to different interactions with central nervous BP control including modified baroreflex function.
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13
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Wahis J, Holt MG. Astrocytes, Noradrenaline, α1-Adrenoreceptors, and Neuromodulation: Evidence and Unanswered Questions. Front Cell Neurosci 2021; 15:645691. [PMID: 33716677 PMCID: PMC7947346 DOI: 10.3389/fncel.2021.645691] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/03/2021] [Indexed: 12/27/2022] Open
Abstract
Noradrenaline is a major neuromodulator in the central nervous system (CNS). It is released from varicosities on neuronal efferents, which originate principally from the main noradrenergic nuclei of the brain - the locus coeruleus - and spread throughout the parenchyma. Noradrenaline is released in response to various stimuli and has complex physiological effects, in large part due to the wide diversity of noradrenergic receptors expressed in the brain, which trigger diverse signaling pathways. In general, however, its main effect on CNS function appears to be to increase arousal state. Although the effects of noradrenaline have been researched extensively, the majority of studies have assumed that noradrenaline exerts its effects by acting directly on neurons. However, neurons are not the only cells in the CNS expressing noradrenaline receptors. Astrocytes are responsive to a range of neuromodulators - including noradrenaline. In fact, noradrenaline evokes robust calcium transients in astrocytes across brain regions, through activation of α1-adrenoreceptors. Crucially, astrocytes ensheath neurons at synapses and are known to modulate synaptic activity. Hence, astrocytes are in a key position to relay, or amplify, the effects of noradrenaline on neurons, most notably by modulating inhibitory transmission. Based on a critical appraisal of the current literature, we use this review to argue that a better understanding of astrocyte-mediated noradrenaline signaling is therefore essential, if we are ever to fully understand CNS function. We discuss the emerging concept of astrocyte heterogeneity and speculate on how this might impact the noradrenergic modulation of neuronal circuits. Finally, we outline possible experimental strategies to clearly delineate the role(s) of astrocytes in noradrenergic signaling, and neuromodulation in general, highlighting the urgent need for more specific and flexible experimental tools.
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Affiliation(s)
- Jérôme Wahis
- Laboratory of Glia Biology, VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, Leuven, Belgium
| | - Matthew G. Holt
- Laboratory of Glia Biology, VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
- Leuven Brain Institute, Leuven, Belgium
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14
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Xu Y, Wang Y, Wang H, Wang C. Synthesis and Characterization of Carbon-11 Labeled Iloperidone for Imaging of α 1-Adrenoceptor in Brain. Front Mol Biosci 2020; 7:586327. [PMID: 33195432 PMCID: PMC7542234 DOI: 10.3389/fmolb.2020.586327] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 09/01/2020] [Indexed: 11/13/2022] Open
Abstract
α1-Adrenoceptor is implicated in numerous neuronal diseases. The development of new modulators targeting this receptor as well as the investigation of the role of α1-adrenoceptor in healthy and disease conditions, however, is hindered by the lack of specific positron emission tomography (PET) radiotracers. Iloperidone shows a high binding affinity to α1-adrenoceptor and moderate selectivity over other brain receptors. We report herein the synthesis and characterization of carbon-11 labeled iloperidone for imaging of α1-adrenoceptor in brain. The radiolabeling of [11C]iloperidone was carried out conveniently in one step by treating precursor with [11C]CH3I in DMF in the presence of K2CO3. Then, [11C]iloperidone was purified by semi-preparative HPLC, and characterized in C57BL/6 mice using PET/CT scanning. The desired product [11C]iloperidone was obtained in an average decay corrected radiochemical of 12% (n = 3) and over 99% radiochemical purity. The average molar radioactivity was 357 GBq/μmol with total synthetic time of 35–40 min. PET/CT scanning in C57BL/6 mice showed favorable pharmacokinetic properties and high brain exposure of [11C]iloperidone. Blocking experiments by pretreatment with the unlabeled iloperidone showed the significant blocking effects with about 25% reduction in brain uptake. These results suggested that [11C]iloperidone can serve as a lead compound for the further development of specific radiotracers for PET imaging of α1-adrenoceptor in brain clinically.
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Affiliation(s)
- Yulong Xu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Yanli Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Hao Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Changning Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
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15
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Ren H, Zuo S, Hou Y, Shang W, Liu N, Yin Z. Inhibition of α1-adrenoceptor reduces TGF-β1-induced epithelial-to-mesenchymal transition and attenuates UUO-induced renal fibrosis in mice. FASEB J 2020; 34:14892-14904. [PMID: 32939891 DOI: 10.1096/fj.202000737rrr] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 08/21/2020] [Accepted: 08/25/2020] [Indexed: 12/11/2022]
Abstract
Renal fibrosis is a common pathological hallmark of chronic kidney disease (CKD). Renal sympathetic nerve activity is elevated in patients and experimental animals with CKD and contributes to renal interstitial fibrosis in obstructive nephropathy. However, the mechanisms underlying sympathetic overactivation in renal fibrosis remain unknown. Norepinephrine (NE), the main sympathetic neurotransmitter, was found to promote TGF-β1-induced epithelial-mesenchymal transition (EMT) and fibrotic gene expression in the human renal proximal epithelial cell line HK-2. Using both genetic and pharmacological approaches, we identified that NE binds Gαq-coupled α1-adrenoceptor (α1-AR) to enhance EMT of HK-2 cells by activating p38/Smad3 signaling. Inhibition of p38 diminished the NE-exaggerated EMT process and increased the fibrotic gene expression in TGF-β1-treated HK-2 cells. Moreover, the pharmacological blockade of α1-AR reduced the kidney injury and renal fibrosis in a unilateral ureteral obstruction mouse model by suppressing EMT in the kidneys. Thus, sympathetic overactivation facilitates EMT of renal epithelial cells and fibrosis via the α1-AR/p38/Smad3 signaling pathway, and α1-AR inhibition may be a promising approach toward treating renal fibrosis.
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Affiliation(s)
- Huiwen Ren
- Department of Pharmacology, Tianjin Key Laboratory of Inflammation Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
| | - Shengkai Zuo
- Department of Pharmacology, Tianjin Key Laboratory of Inflammation Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
| | - Yayan Hou
- Department of Pharmacology, Tianjin Key Laboratory of Inflammation Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
| | - Wenlong Shang
- Department of Pharmacology, Tianjin Key Laboratory of Inflammation Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
| | - Na Liu
- Department of Pharmacology, Tianjin Key Laboratory of Inflammation Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, China
| | - Zhuming Yin
- Department of Breast Oncoplastic Surgery, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China.,National Clinical Research Center for Cancer, Tianjin, China.,Sino-Russian Joint Research Center for Oncoplastic Breast Surgery, Tianjin, China.,Key Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education, Tianjin, China.,Key Laboratory of Cancer Prevention and Therapy, Tianjin, China.,Tianjin's Clinical Research Center for Cancer, Tianjin, China
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16
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Choy JMC, Agahari FA, Li L, Stricker C. Noradrenaline Increases mEPSC Frequency in Pyramidal Cells in Layer II of Rat Barrel Cortex via Calcium Release From Presynaptic Stores. Front Cell Neurosci 2018; 12:213. [PMID: 30100867 PMCID: PMC6072855 DOI: 10.3389/fncel.2018.00213] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 06/28/2018] [Indexed: 11/20/2022] Open
Abstract
Somatosensory cortex is innervated by afferents originating from the locus coeruleus which typically release noradrenaline. We tested if activation of presynaptic α1-adrenoceptors (AR) coupled to a Gq-mediated signaling cascade resulted in calcium (Ca2+) release from stores and thereby increased spontaneous transmitter release in rat barrel cortex. Adding 1–100 μM noradrenaline (NA) or 5 μM cirazoline (CO), a α1-AR specific agonist, to the standard artificial cerebrospinal fluid increased the frequency of miniature excitatory postsynaptic currents (mEPSC) by 64 ± 7% in 51% of pyramidal cells in layer II (responders) with no effect on the amplitude. In 42 responders, the mEPSC frequency during control was significantly smaller (39 ± 2 vs. 53 ± 4 Hz) and upon NA exposure, the input resistance (Rin) decreased (9 ± 7%) compared to non-responders. Experiments using CO and the antagonist prazosin revealed that NA acted via binding to α1-ARs, which was further corroborated by simultaneously blocking β- and α2-ARs with propranolol and yohimbine, which did not prevent the increase in mEPSC frequency. To verify elements in the signaling cascade, both the phospholipase C inhibitor edelfosine and the membrane permeable IP3 receptor blocker 2-APB averted the increase in mEPSC frequency. Likewise, emptying Ca2+ stores with cyclopiazonic acid or the chelation of intracellular Ca2+ with BAPTA-AM prevented the frequency increase, suggesting that the frequency increase was caused by presynaptic store release. When group I metabotropic glutamate receptors were activated with DHPG, co-application of NA occluded a further frequency increase suggesting that the two receptor activations may not signal independently of each other. The increased mEPSC frequency in a subset of pyramidal cells results in enhanced synaptic noise, which, together with the reduction in Rin, will affect computation in the network.
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Affiliation(s)
- Julian M C Choy
- Neuronal Network Laboratory, Eccles Institute of Neuroscience, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Fransiscus A Agahari
- Neuronal Network Laboratory, Eccles Institute of Neuroscience, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia.,Division of Cerebral Circuitry, National Institute for Physiological Sciences, Okazaki, Japan
| | - Li Li
- Neuronal Network Laboratory, Eccles Institute of Neuroscience, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia.,Zhejiang Provincial Key Laboratory of Anesthesiology, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Christian Stricker
- Neuronal Network Laboratory, Eccles Institute of Neuroscience, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia.,ANU Medical School, Australian National University, Canberra, ACT, Australia
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17
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Hennenberg M, Kuppermann P, Yu Q, Herlemann A, Tamalunas A, Wang Y, Rutz B, Ciotkowska A, Strittmatter F, Stief CG, Gratzke C. Inhibition of Prostate Smooth Muscle Contraction by Inhibitors of Polo-Like Kinases. Front Physiol 2018; 9:734. [PMID: 29962965 PMCID: PMC6013909 DOI: 10.3389/fphys.2018.00734] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/25/2018] [Indexed: 11/23/2022] Open
Abstract
Background: Prostate smooth muscle contraction plays an important role for pathophysiology and treatment of male lower urinary tract symptoms (LUTS) but is incompletely understood. Because the efficacy of available medication is limited, novel options and improved understanding of prostate smooth muscle contraction are of high demand. Recently, a possible role of polo-like kinase 1 (PLK1) has been suggested for smooth muscle contraction outside the lower urinary tract. Here, we examined effects of PLK inhibitors on contraction of human prostate tissue. Methods: Prostate tissues were obtained from radical prostatectomy. RT-PCR, Western blot and immunofluorescence were performed to detect PLK expression and phosphorylated PLK. Smooth muscle contractions were induced by electric field stimulation (EFS), α1-agonists, endothelin-1, or the thromboxane A2 analog U46619 in organ bath. Results: RT-PCR, Western blot, and immunofluorescence suggested expression of PLK1 in the human prostate, which may be located and active in smooth muscle cells. EFS-induced contractions of prostate strips were reduced by SBE 13 (1 μM), cyclapolin 9 (3 μM), TAK 960 (100 nM), and Ro 3280 (100 nM). SBE 13 and cyclapolin 9 inhibited contractions by the α1-agonists methoxamine, phenylephrine, and noradrenaline. In contrast, no effects of SBE 13 or cyclapolin 9 on endothelin-1- or U46619-induced contractions were observed. Conclusion: Alpha1-adrenergic smooth muscle contraction in the human prostate can be inhibited by PLK inhibitors. PLK-dependent signaling may be a new pathway, which promotes α1-adrenergic contraction of prostate smooth muscle cells. As contractions by endothelin and U46619 are not susceptible to PLK inhibition, this reflects divergent regulation of adrenergic and non-adrenergic prostate smooth muscle contraction.
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Affiliation(s)
- Martin Hennenberg
- Department of Urology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Paul Kuppermann
- Department of Urology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Qingfeng Yu
- Department of Urology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Annika Herlemann
- Department of Urology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Alexander Tamalunas
- Department of Urology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Yiming Wang
- Department of Urology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Beata Rutz
- Department of Urology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Anna Ciotkowska
- Department of Urology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Frank Strittmatter
- Department of Urology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Christian G Stief
- Department of Urology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Christian Gratzke
- Department of Urology, Ludwig Maximilian University of Munich, Munich, Germany
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18
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Zhang X, Xu X, Jiang Y, He J, Wang W, Li W, Zhang X, Lv Y. Induction of renal artery hyperresponsiveness by alpha1-adrenoceptor in hepatorenal syndrome. Oncotarget 2017; 8:109258-109270. [PMID: 29312606 PMCID: PMC5752519 DOI: 10.18632/oncotarget.22668] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 06/29/2017] [Indexed: 01/01/2023] Open
Abstract
Objective To investigate the potential role of alpha1-adrenoceptor (α1-AR) in the pathogenesis of hepatorenal syndrome. Methods Hepatorenal syndrome was induced in male rats by intraperitoneal injection of D-galactosamine and orally treatment with α1-AR antagonist tamsulosin. Hyperresponsiveness of the renal artery contraction was evaluated by the laser-Doppler flowmetry and multimyograph system, while renal blood flow (cortical and medullary perfusion) was simultaneously measured. Renal artery ring segment tone was recorded with the myograph system, and concentration-response curves were obtained by cumulative administration of agonists. Results This model developed acute renal and liver failure without renal damage in pathology, accompanied by significant hyperresponsiveness of renal artery contraction. After hepatorenal syndrome, plasma concentrations of tumor necrosis factor-α increased by two-fold, and α1-AR was significantly activated in the renal artery. Concentration-dependent vasoconstriction induced by noradrenaline was significantly decreased in the renal arteries of hepatorenal syndrome rat because of gradually decreased renal blood flow. Administration of tamsulosin prevented renal failure when given before the onset of liver injury, but it had no effect on liver injury by itself. Conclusion α1-AR expression is positively associated with renal vasoconstriction induced by renal artery hyperresponsiveness in HRS. Therefore, α1-AR may be a potential target in the treatment of HRS.
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Affiliation(s)
- Xiaogang Zhang
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University College of Medicine, Xi'an 710061, China
| | - Xinsen Xu
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University College of Medicine, Xi'an 710061, China
| | - Yina Jiang
- Department of Pathology, First Affiliated Hospital of Xi'an Jiaotong University College of Medicine, Xi'an 710061, China
| | - Jianyu He
- Department of Pharmacology, First Affiliated Hospital of Xi'an Jiaotong University College of Medicine, Xi'an 710061, China
| | - Wenjing Wang
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University College of Medicine, Xi'an 710061, China
| | - Wei Li
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University College of Medicine, Xi'an 710061, China
| | - Xufeng Zhang
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University College of Medicine, Xi'an 710061, China
| | - Yi Lv
- Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University College of Medicine, Xi'an 710061, China
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19
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Zefirov TL, Khabibrakhmanov II, Ziyatdinova NI, Zefirov AL. Peculiar Aspects in Influence of α 1-Adrenoceptor Stimulation on Isolated Rat Heart. Bull Exp Biol Med 2016; 162:4-6. [PMID: 27878488 DOI: 10.1007/s10517-016-3530-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Indexed: 11/26/2022]
Abstract
The study examined the effect of α1-adrenoceptor stimulation with methoxamine on chronotropic function of isolated heart perfused ex vivo according to Langendorff and cardiac chronotropy in vivo. Stimulation of α1-adrenoceptors in isolated heart induced gradually developing bradycardia, which progressed during several minutes. Similar stimulation in vivo produced a short-term bradycardia probably terminated by the compensatory influences in the whole organism. Comparison of the data obtained in both experimental paradigms during α1-adrenoceptor stimulation revealed unidirectional changes in cardiac chronotropy characterized with time-related peculiarities.
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Affiliation(s)
- T L Zefirov
- Department of Human Health Protection, Kazan (Volga Region) Federal University, Kazan, the Republic of Tatarstan, Russia.
| | - I I Khabibrakhmanov
- Department of Human Health Protection, Kazan (Volga Region) Federal University, Kazan, the Republic of Tatarstan, Russia
| | - N I Ziyatdinova
- Department of Human Health Protection, Kazan (Volga Region) Federal University, Kazan, the Republic of Tatarstan, Russia
| | - A L Zefirov
- Department of Normal Physiology, Kazan Federal Medical University, Kazan, the Republic of Tatarstan, Russia
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Shrestha SS, Liow JS, Jenko K, Ikawa M, Zoghbi SS, Innis RB. The 5-HT1A Receptor PET Radioligand 11C-CUMI-101 Has Significant Binding to α1-Adrenoceptors in Human Cerebellum, Limiting Its Use as a Reference Region. J Nucl Med 2016; 57:1945-1948. [PMID: 27587705 DOI: 10.2967/jnumed.116.174151] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 07/19/2016] [Indexed: 11/16/2022] Open
Abstract
Prazosin, a potent and selective α1-adrenoceptor antagonist, displaces 25% of 11C-CUMI-101 ([O-methyl-11C]2-(4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl)-4-methyl-1,2,4-triazine-3,5(2H,4H)dione) binding in monkey cerebellum. We sought to estimate the percentage contamination of 11C-CUMI-101 binding to α1-adrenoceptors in human cerebellum under in vivo conditions. In vitro receptor-binding techniques were used to measure α1-adrenoceptor density and the affinity of CUMI-101 for these receptors in human, monkey, and rat cerebellum. METHODS Binding potential (maximum number of binding sites × affinity [(1/dissociation constant]) was determined using in vitro homogenate binding assays in human, monkey, and rat cerebellum. 3H-prazosin was used to determine the maximum number of binding sites, as well as the dissociation constant of 3H-prazosin and the inhibition constant of CUMI-101. RESULTS α1-adrenoceptor density and the affinity of CUMI-101 for these receptors were similar across species. Cerebellar binding potentials were 3.7 for humans, 2.3 for monkeys, and 3.4 for rats. CONCLUSION Reasoning by analogy, 25% of 11C-CUMI-101 uptake in human cerebellum reflects binding to α1-adrenoceptors, suggesting that the cerebellum is of limited usefulness as a reference tissue for quantification in human studies.
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Affiliation(s)
- Stal S Shrestha
- Molecular Imaging Branch, National Institute of Mental Health Intramural Research Program, Bethesda, Maryland
| | - Jeih-San Liow
- Molecular Imaging Branch, National Institute of Mental Health Intramural Research Program, Bethesda, Maryland
| | - Kimberly Jenko
- Molecular Imaging Branch, National Institute of Mental Health Intramural Research Program, Bethesda, Maryland
| | - Masamichi Ikawa
- Molecular Imaging Branch, National Institute of Mental Health Intramural Research Program, Bethesda, Maryland
| | - Sami S Zoghbi
- Molecular Imaging Branch, National Institute of Mental Health Intramural Research Program, Bethesda, Maryland
| | - Robert B Innis
- Molecular Imaging Branch, National Institute of Mental Health Intramural Research Program, Bethesda, Maryland
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Yu X, Jia B, Wang F, Lv X, Peng X, Wang Y, Li H, Wang Y, Lu D, Wang H. α₁ adrenoceptor activation by norepinephrine inhibits LPS-induced cardiomyocyte TNF-α production via modulating ERK1/2 and NF-κB pathway. J Cell Mol Med 2014; 18:263-73. [PMID: 24304472 PMCID: PMC3930413 DOI: 10.1111/jcmm.12184] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 10/08/2013] [Indexed: 02/05/2023] Open
Abstract
Cardiomyocyte tumour necrosis factor α (TNF-α) production contributes to myocardial depression during sepsis. This study was designed to observe the effect of norepinephrine (NE) on lipopolysaccharide (LPS)-induced cardiomyocyte TNF-α expression and to further investigate the underlying mechanisms in neonatal rat cardiomyocytes and endotoxaemic mice. In cultured neonatal rat cardiomyocytes, NE inhibited LPS-induced TNF-α production in a dose-dependent manner. α₁- adrenoceptor (AR) antagonist (prazosin), but neither β₁- nor β₂-AR antagonist, abrogated the inhibitory effect of NE on LPS-stimulated TNF-α production. Furthermore, phenylephrine (PE), an α₁-AR agonist, also suppressed LPS-induced TNF-α production. NE inhibited p38 phosphorylation and NF-κB activation, but enhanced extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation and c-Fos expression in LPS-treated cardiomyocytes, all of which were reversed by prazosin pre-treatment. To determine whether ERK1/2 regulates c-Fos expression, p38 phosphorylation, NF-κB activation and TNF-α production, cardiomyocytes were also treated with U0126, a selective ERK1/2 inhibitor. Treatment with U0126 reversed the effects of NE on c-Fos expression, p38 mitogen-activated protein kinase (MAPK) phosphorylation and TNF-α production, but not NF-κB activation in LPS-challenged cardiomyocytes. In addition, pre-treatment with SB202190, a p38 MAPK inhibitor, partly inhibited LPS-induced TNF-α production in cardiomyocytes. In endotoxaemic mice, PE promoted myocardial ERK1/2 phosphorylation and c-Fos expression, inhibited p38 phosphorylation and IκBα degradation, reduced myocardial TNF-α production and prevented LPS-provoked cardiac dysfunction. Altogether, these findings indicate that activation of α₁-AR by NE suppresses LPS-induced cardiomyocyte TNF-α expression and improves cardiac dysfunction during endotoxaemia via promoting myocardial ERK phosphorylation and suppressing NF-κB activation.
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Affiliation(s)
- Xiaohui Yu
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan UniversityGuangzhou, Guangdong, China
| | - Baoyin Jia
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan UniversityGuangzhou, Guangdong, China
| | - Faqiang Wang
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan UniversityGuangzhou, Guangdong, China
| | - Xiuxiu Lv
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan UniversityGuangzhou, Guangdong, China
| | - Xuemei Peng
- Department of Anesthesiology, The First Affiliated Hospital, Jinan UniversityGuangzhou, Guangdong, China
| | - Yiyang Wang
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan UniversityGuangzhou, Guangdong, China
| | - Hongmei Li
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan UniversityGuangzhou, Guangdong, China
| | - Yanping Wang
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan UniversityGuangzhou, Guangdong, China
| | - Daxiang Lu
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan UniversityGuangzhou, Guangdong, China
| | - Huadong Wang
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan UniversityGuangzhou, Guangdong, China
- *Correspondence to: Prof. Huadong WANG, M.D., Ph.D., Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan University, Guangzhou, Guangdong 510632, China., Tel.: 86-20-85220241, Fax: 86-20-85221343, E-mail:
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Docherty JR, Bexis S. Influence of ketanserin on the effects of methylenedioxymethamphetamine on body temperature in the mouse. Auton Autacoid Pharmacol 2013; 33:35-41. [PMID: 23906337 DOI: 10.1111/aap.12009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 04/18/2013] [Accepted: 05/13/2013] [Indexed: 06/02/2023]
Abstract
(1) We have investigated the ability of the 5HT2 -receptor antagonist ketanserin to affect the hyperthermia produced by methylenedioxymethamphetamine (MDMA) in conscious mice and examined whether α1 -adrenoceptor antagonist actions are involved. (2) Mice were implanted with intra-abdominal temperature probes under anaesthesia and allowed 2 weeks recovery. MDMA (20 mg kg(-1) ) was administered subcutaneously 30 min after vehicle or test antagonist and effects on body temperature monitored by telemetry. (3) Following vehicle, MDMA produced a slowly developing hyperthermia, reaching a maximum increase of 1.24 °C at 150 min postinjection. Ketanserin (0.5 mg kg(-1) ) revealed a significant and marked early hypothermia to MDMA, an effect that is mimicked by the α1 -adrenoceptor antagonist prazosin (0.1 mg kg(-1) ). (4) Functional studies revealed antagonist actions of ketanserin at α1 -adrenoceptors in rat aorta and rat vas deferens in vitro indicative of α1 -adrenoceptor antagonist actions at the concentration used in vivo. (5) In conclusion, ketanserin (0.5 mg kg(-1) ) modulates the hyperthermic actions of MDMA in mice. Although we cannot rule out additional actions at 5HT2 -receptors, the actions of ketanserin are consistent with α1 -adrenoceptor antagonism. There is no clear evidence from this study that 5HT2-receptors mediate the hyperthermic response to MDMA.
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Affiliation(s)
- J R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, 123 St Stephen's Green, Dublin, Ireland
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Hennenberg M, Miljak M, Herrmann D, Strittmatter F, Walther S, Rutz B, Hocaoglu Y, Kunit T, Schreiber A, Andersson KE, Stief CG, Gratzke C. The receptor antagonist picotamide inhibits adrenergic and thromboxane-induced contraction of hyperplastic human prostate smooth muscle. Am J Physiol Renal Physiol 2013; 305:F1383-90. [PMID: 24049147 DOI: 10.1152/ajprenal.00380.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Inhibition of prostate smooth muscle contraction is an important strategy for medical treatment of lower urinary tract symptoms (LUTS). Besides α1-adrenoceptors, prostate smooth muscle contraction is induced by activation of thromboxane (TXA2) receptors (TXA2-R). Here, we examined the effects of the TXA2-R antagonist picotamide on contraction of human prostate tissue. Prostate tissues were obtained from radical prostatectomy. The effects of picotamide (300 μM), L-665,240 (3 μM), and seratrodast (3 μM) on U46619-, electric field stimulation- (EFS-), phenylephrine-, and norepinephrine-induced contractions were studied in organ baths. Expression of TXA2-R and TXA2 synthase (TXS) was examined by fluorescence stainings. Picotamide, seratrodast, and L-655,240 inhibited concentration-dependent contractions induced by the TXA2 analog U46619. Picotamide, but not seratrodast or L-655,240, inhibited frequency-dependent contractions induced by EFS. Picotamide inhibited concentration-dependent contractions induced by norepinephrine or by the selective α1-adrenoceptor agonist phenylephrine. In prostate strips, where only submaximal contraction by a low dose of phenylephrine was induced, application of U46619 raised tone to maximum phenylephrine-induced tension. Immunoreactivity for TXA2-R and TXS was observed in the stroma and in epithelial cells of glands. Colocalization of both immunoreactivites was observed with the smooth muscle markers calponin and α-smooth muscle actin, with the epithelial marker pan-cytokeratin, and with prostate-specific antigen in the stroma and glands. The receptor antagonist picotamide inhibits α1-adrenergic, TXA2-mediated, and EFS-induced contractions in the human prostate. To the best of our knowledge, this is the first antagonist able to inhibit two different contraction systems in the prostate.
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Jin XT, Cui N, Zhong W, Jin X, Wu Z, Jiang C. Pre- and postsynaptic modulations of hypoglossal motoneurons by α-adrenoceptor activation in wild-type and Mecp2(-/Y) mice. Am J Physiol Cell Physiol 2013; 305:C1080-90. [PMID: 23986203 DOI: 10.1152/ajpcell.00109.2013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypoglossal motoneurons (HNs) control tongue movement and play a role in maintenance of upper airway patency. Defects in these neurons may contribute to the development of sleep apnea and other cranial motor disorders including Rett syndrome (RTT). HNs are modulated by norepinephrine (NE) through α-adrenoceptors. Although postsynaptic mechanisms are known to play a role in this effect, how NE modulates the synaptic transmissions of HNs remains poorly understood. More importantly, the NE system is defective in RTT, while how the defect affects HNs is unknown. Believing that information of NE modulation of HNs may help the understanding of RTT and the design of new therapeutical interventions to motor defects in the disease, we performed these studies in which glycinergic inhibitory postsynaptic currents and intrinsic membrane properties were examined in wild-type and Mecp2(-/Y) mice, a mouse of model of RTT. We found that activation of α1-adrenoceptor facilitated glycinergic synaptic transmission and excited HNs. These effects were mediated by both pre- and postsynaptic mechanisms. The latter effect involved an inhibition of barium-sensitive G protein-dependent K(+) currents. The pre- and postsynaptic modulations of the HNs by α1-adrenoceptors were not only retained in Mecp2-null mice but also markedly enhanced, which appears to be a compensatory mechanism for the deficiencies in NE and GABAergic synaptic transmission. The existence of the endogenous compensatory mechanism is an encouraging finding, as it may allow therapeutical modalities to alleviate motoneuronal defects in RTT.
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Affiliation(s)
- Xiao-Tao Jin
- Department of Biology, Georgia State University, Atlanta, Georgia
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