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Arkhipov A, Khuzakhmetova V, Petrov AM, Bukharaeva EA. Catecholamine-dependent hyperpolarization of the junctional membrane via β2- adrenoreceptor/G i-protein/α2-Na-K-ATPase pathway. Brain Res 2022; 1795:148072. [PMID: 36075465 DOI: 10.1016/j.brainres.2022.148072] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/26/2022] [Accepted: 09/01/2022] [Indexed: 11/15/2022]
Abstract
We investigated the effects of catecholamines, adrenaline and noradrenaline, as well as β-adrenoceptor (AR) modulators on a resting membrane potential at the junctional and extrajunctional regions of mouse fast-twitch Levator auris longus muscle. The aim of the study was to find which AR subtypes, signaling molecules and Na,K-ATPase isoforms are involved in the hyperpolarizing action of catecholamines and whether this action could be accompanied by changes in the pump abundance on the sarcolemma. Adrenaline, noradrenaline and specific β2-AR agonist induced hyperpolarization of both junctional and extrajunctional membrane, but the underlying mechanisms were different. In the junctional membrane the hyperpolarization depended on α2 isoform of the Na,K-ATPase and Gi-protein, whereas in the extrajunctional regions the hyperpolarization mainly relied on α1 isoform of Na,K-ATPase and adenylyl cyclase activities. In both junctional and extrajunctional regions, AR activation caused an increase in Na,K-ATPase abundance in the plasmalemma in a protein kinase A-dependent manner. Thus, the compartment-specific mechanisms are responsible for catecholamine-mediated hyperpolarization in the skeletal muscle.
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Affiliation(s)
- Arsenii Arkhipov
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Federal Research Center ''Kazan Scientific Center of RAS", 2/31 Lobachevsky St, box 30, Kazan, RT 420111, Russia
| | - Venera Khuzakhmetova
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Federal Research Center ''Kazan Scientific Center of RAS", 2/31 Lobachevsky St, box 30, Kazan, RT 420111, Russia
| | - Alexey M Petrov
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Federal Research Center ''Kazan Scientific Center of RAS", 2/31 Lobachevsky St, box 30, Kazan, RT 420111, Russia; Kazan State Medial University, 49 Butlerova St., Kazan, RT 420012, Russia.
| | - Ellya A Bukharaeva
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Federal Research Center ''Kazan Scientific Center of RAS", 2/31 Lobachevsky St, box 30, Kazan, RT 420111, Russia
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Koh M, Takahashi T, Kurokawa Y, Kobayashi T, Saito T, Ishida T, Serada S, Fujimoto M, Naka T, Wada N, Yamashita K, Tanaka K, Miyazaki Y, Makino T, Nakajima K, Yamasaki M, Eguchi H, Doki Y. Propranolol suppresses gastric cancer cell growth by regulating proliferation and apoptosis. Gastric Cancer 2021; 24:1037-1049. [PMID: 33782804 DOI: 10.1007/s10120-021-01184-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 03/11/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND Despite improvements in gastric cancer treatment, the mortality associated with advanced gastric cancer is still high. The activation of β-adrenergic receptors by stress has been shown to accelerate the progression of several cancers. Accordingly, increasing evidence suggests that the blockade of β-adrenergic signaling can inhibit tumor growth. However, the effect of β-blockers, which target several signaling pathways, on gastric cancer remains to be elucidated. This study aimed to investigate the anti-tumor effects of propranolol, a non-selective β-blocker, on gastric cancer. METHODS We explored the effect of propranolol on the MKN45 and NUGC3 gastric cancer cell lines. Its efficacy and the mechanism by which it exerts anti-tumor effects were examined using several assays (e.g., cell proliferation, cell cycle, apoptosis, and wound healing) and a xenograft mouse model. RESULTS We found that propranolol inhibited tumor growth and induced G1-phase cell cycle arrest and apoptosis in both cell lines. Propranolol also decreased the expression of phosphorylated CREB-ATF and MEK-ERK pathways; suppressed the expression of matrix metalloproteinase-2, 9 and vascular endothelial growth factor; and inhibited gastric cancer cell migration. In the xenograft mouse model, propranolol treatment significantly inhibited tumor growth, and immunohistochemistry revealed that propranolol led to the suppression of proliferation and induction of apoptosis. CONCLUSIONS Propranolol inhibits the proliferation of gastric cancer cells by inducing G1-phase cell cycle arrest and apoptosis. These findings indicate that propranolol might have an opportunity as a new drug for gastric cancer.
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Affiliation(s)
- Masahiro Koh
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Tsuyoshi Takahashi
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Yukinori Kurokawa
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Teruyuki Kobayashi
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Takuro Saito
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Tomo Ishida
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Satoshi Serada
- Center for Intractable Disease, Kochi University, Nankoku, Japan
| | - Minoru Fujimoto
- Center for Intractable Disease, Kochi University, Nankoku, Japan
| | - Tetsuji Naka
- Center for Intractable Disease, Kochi University, Nankoku, Japan
| | - Noriko Wada
- Department of Surgery, Ikeda City Hospital, Ikeda, Japan
| | - Kotaro Yamashita
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Koji Tanaka
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yasuhiro Miyazaki
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Tomoki Makino
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kiyokazu Nakajima
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Makoto Yamasaki
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hidetoshi Eguchi
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yuichiro Doki
- Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
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Apostolakou AE, Baltoumas FA, Stravopodis DJ, Iconomidou VA. Extended Human G-Protein Coupled Receptor Network: Cell-Type-Specific Analysis of G-Protein Coupled Receptor Signaling Pathways. J Proteome Res 2019; 19:511-524. [PMID: 31774292 DOI: 10.1021/acs.jproteome.9b00754] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
G-protein coupled receptors (GPCRs) mediate crucial physiological functions in humans, have been implicated in an array of diseases, and are therefore prime drug targets. GPCRs signal via a multitude of pathways, mainly through G-proteins and β-arrestins, to regulate effectors responsible for cellular responses. The limited number of transducers results in different GPCRs exerting control on the same pathway, while the availability of signaling proteins in a cell defines the result of GPCR activation. The aim of this study was to construct the extended human GPCR network (hGPCRnet) and examine the effect that cell-type specificity has on GPCR signaling pathways. To achieve this, protein-protein interaction data between GPCRs, G-protein coupled receptor kinases (GRKs), Gα subunits, β-arrestins, and effectors were combined with protein expression data in cell types. This resulted in the hGPCRnet, a very large interconnected network, and similar cell-type-specific networks in which, distinct GPCR signaling pathways were formed. Finally, a user friendly web application, hGPCRnet ( http://bioinformatics.biol.uoa.gr/hGPCRnet ), was created to allow for the visualization and exploration of these networks and of GPCR signaling pathways. This work, and the resulting application, can be useful in further studies of GPCR function and pharmacology.
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Affiliation(s)
- Avgi E Apostolakou
- Section of Cell Biology and Biophysics, Department of Biology, School of Sciences , National and Kapodistrian University of Athens , Panepistimiopolis , Athens 15701 , Greece
| | - Fotis A Baltoumas
- Section of Cell Biology and Biophysics, Department of Biology, School of Sciences , National and Kapodistrian University of Athens , Panepistimiopolis , Athens 15701 , Greece
| | - Dimitrios J Stravopodis
- Section of Cell Biology and Biophysics, Department of Biology, School of Sciences , National and Kapodistrian University of Athens , Panepistimiopolis , Athens 15701 , Greece
| | - Vassiliki A Iconomidou
- Section of Cell Biology and Biophysics, Department of Biology, School of Sciences , National and Kapodistrian University of Athens , Panepistimiopolis , Athens 15701 , Greece
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Muthuswamy R, Okada NJ, Jenkins FJ, McGuire K, McAuliffe PF, Zeh HJ, Bartlett DL, Wallace C, Watkins S, Henning JD, Bovbjerg DH, Kalinski P. Epinephrine promotes COX-2-dependent immune suppression in myeloid cells and cancer tissues. Brain Behav Immun 2017; 62:78-86. [PMID: 28212885 DOI: 10.1016/j.bbi.2017.02.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 01/14/2017] [Accepted: 02/13/2017] [Indexed: 01/17/2023] Open
Abstract
Activation of the sympathetic nervous system (e.g., due to stress) has been implicated in cancer progression and recurrence, but its cancer-promoting effects have been variable between different studies. Here, we report that although catecholamines, mediators of systemic sympathetic activity, display only weak immunosuppressive impact on their own, their combination with inflammatory signals leads to the induction of COX-2 and multiple COX-2-dependent suppressive factors in human myeloid cells and cancer tissues. Human macrophages exposed to epinephrine and TNFα, or macrophages generated in 6day cultures in the presence of epinephrine, expressed high levels of COX-2, IDO and IL-10, and strongly suppressed both the proliferation and IFNγ production of CD8+ T cells. These suppressive effects of epinephrine were counteracted by celecoxib, a selective inhibitor of COX-2 activity, which inhibited the induction of immunosuppressive factors (including the elevated expression of COX-2 itself) and the ability of epinephrine-exposed macrophages to suppress CD8+ T cell responses. The activation of the COX-2/PGE2 system and COX-2-dependent suppressive events were also observed in ex vivo human breast and colon cancer explant cultures and were similarly counteracted by celecoxib. Our preliminary data also indicate elevated COX-2 expression in mammary tumors of chronic stress-exposed mice. The current demonstration of the interplay between inflammation and the induction of immunosuppressive factors by catecholamines suggest a contextual impact of stress, helping to explain variable results of epidemiologic studies of the link between sympathetic activity and cancer progression, and implicating COX-2 blockade as a potential means to mitigate stress-related immune suppression.
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Affiliation(s)
| | - Nana J Okada
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Frank J Jenkins
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15213, USA; The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA
| | - Kandace McGuire
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA; The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA
| | - Priscilla F McAuliffe
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA; The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA
| | - Herbert J Zeh
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA; The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA
| | - David L Bartlett
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA; The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA
| | - Callen Wallace
- Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Simon Watkins
- Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Jill D Henning
- Department of Psychiatry, Psychology and Behavioral & Community Health Sciences, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Biology, University of Pittsburgh at Johnstown, Johnstown, PA 15904, USA
| | - Dana H Bovbjerg
- The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA; Department of Psychiatry, Psychology and Behavioral & Community Health Sciences, University of Pittsburgh, Pittsburgh, PA 15213, USA.
| | - Pawel Kalinski
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA; The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA; Department of Infectious Diseases and Microbiology, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Immunology, University of Pittsburgh, Pittsburgh, PA 15213, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, USA.
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Mao HP, Wang XY, Gao YH, Chang YX, Chen L, Niu ZC, Ai JQ, Gao XM. Danhong injection attenuates isoproterenol-induced cardiac hypertrophy by regulating p38 and NF-κb pathway. JOURNAL OF ETHNOPHARMACOLOGY 2016; 186:20-29. [PMID: 26970569 DOI: 10.1016/j.jep.2016.03.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 12/23/2015] [Accepted: 03/07/2016] [Indexed: 06/05/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Danhong injection (DHI), derived from Rhizoma Salviae Miltiorrhizae (Salvia miltiorrhiza Bge., Labiatae, Danshen in Chinese) and Flos Carthami (Carthamus tinctorius L., Compositae, Salvia militiorrhiza Bunge), is an extensively-used Chinese material standardized clinical product for treatment of cardiovascular diseases. AIM OF THE STUDY Cardiac hypertrophy (CH) is an adaptive response of cardiomyocytes. Long-lasting cardiac hypertrophy results in the loss of compensation by cardiomyocytes which could ultimately develop into heart failure. In the present study, we aimed to investigate the effect and exact mechanisms of DHI on isoproterenol (ISO)-induced CH. MATERIALS AND METHODS H9c2 cells and male Wistar rats were stimulated by ISO in the present study to establish CH models in vitro and in vivo. CCk-8 assay, Western blot, real time-polymerase chain reaction (RT-PCR), electrophoretic mobility shift assay (EMSA) and Echocardiography were used in the present study. RESULTS DHI significantly attenuated ISO-induced CH of H9c2 cells (p<0.01). DHI decreased ISO-induced atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) elevation both at the mRNA and protein levels (p<0.05 and p<0.01, respectively). Western blot showed that DHI down-regulated the phosphorylation of p38. Furthermore, we found that DHI inhibited the nuclear translocation and activation of NF-κb. Echocardiography from ISO-induced CH rats showed that DHI significantly decreased left ventricle (LV) mass, the thickness of the LV end-systolic posterior wall (LVPWs), and the LV end-diastolic posterior wall (LVPWd) elevated by ISO (p<0.01 and p<0.05, respectively). CONCLUSION These data demonstrate that DHI might exert anti-cardiac hypertrophic effects by regulating p38 and NF-κb pathway.
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Affiliation(s)
- Hao-Ping Mao
- Tianjin State Key Laboratory of Modern Chinese Medicine, Key Laboratory of Pharmacology of Traditional Chinese Medicine Formulae, and Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China.
| | - Xing-Ye Wang
- Tianjin State Key Laboratory of Modern Chinese Medicine, Key Laboratory of Pharmacology of Traditional Chinese Medicine Formulae, and Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China.
| | - Yun Hang Gao
- Tianjin State Key Laboratory of Modern Chinese Medicine, Key Laboratory of Pharmacology of Traditional Chinese Medicine Formulae, and Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China.
| | - Yan-Xu Chang
- Tianjin State Key Laboratory of Modern Chinese Medicine, Key Laboratory of Pharmacology of Traditional Chinese Medicine Formulae, and Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Lu Chen
- Tianjin State Key Laboratory of Modern Chinese Medicine, Key Laboratory of Pharmacology of Traditional Chinese Medicine Formulae, and Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China.
| | - Zi-Chang Niu
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, China.
| | - Ju-Qing Ai
- Tianjin State Key Laboratory of Modern Chinese Medicine, Key Laboratory of Pharmacology of Traditional Chinese Medicine Formulae, and Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China.
| | - Xiu-Mei Gao
- Tianjin State Key Laboratory of Modern Chinese Medicine, Key Laboratory of Pharmacology of Traditional Chinese Medicine Formulae, and Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China.
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CREB-binding protein (CBP) regulates β-adrenoceptor (β-AR)-mediated apoptosis. Cell Death Differ 2013; 20:941-52. [PMID: 23579242 DOI: 10.1038/cdd.2013.29] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Catecholamines regulate the β-adrenoceptor/cyclic AMP-regulated protein kinase A (cAMP/PKA) pathway. Deregulation of this pathway can cause apoptotic cell death and is implicated in a range of human diseases, such as neuronal loss during aging, cardiomyopathy and septic shock. The molecular mechanism of this process is, however, only poorly understood. Here we demonstrate that the β-adrenoceptor/cAMP/PKA pathway triggers apoptosis through the transcriptional induction of the pro-apoptotic BH3-only Bcl-2 family member Bim in tissues such as the thymus and the heart. In these cell types, the catecholamine-mediated apoptosis is abrogated by loss of Bim. Induction of Bim is driven by the transcriptional co-activator CBP (CREB-binding protein) together with the proto-oncogene c-Myc. Association of CBP with c-Myc leads to altered histone acetylation and methylation pattern at the Bim promoter site. Our findings have implications for understanding pathophysiology associated with a deregulated neuroendocrine system and for developing novel therapeutic strategies for these diseases.
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Sun J, Fu L, Tang X, Han Y, Ma D, Cao J, Kang N, Ji H. Testosterone modulation of cardiac β-adrenergic signals in a rat model of heart failure. Gen Comp Endocrinol 2011; 172:518-25. [PMID: 21549119 DOI: 10.1016/j.ygcen.2011.04.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 03/16/2011] [Accepted: 04/20/2011] [Indexed: 01/08/2023]
Abstract
In this study, we examined the effects of castration and testosterone replacement on β-adrenoceptor and G protein expression in rats subjected to doxorubicin-induced heart failure. Five groups were included in this report: control, sham-castration with heart failure, castration with heart failure, castration+testosterone replacement with heart failure and castration+testosterone replacement and flutamide with heart failure. At 4 weeks post-treatment, echocardiography, hemodynamics and histopathology were assessed. Castration led to a further deterioration in myocardial performance, apoptosis and fibrosis, while testosterone replacement ameliorated these effects. Data obtained from Western blots revealed that testosterone upregulated the expression of β(2)-adrenoceptor, Gs, Gi(2) and bcl2 levels, downregulated the expression of β(3)-adrenoceptor, Gi(3) and GRK2 levels, and did not modify the expression of β(1)-adrenoceptor levels in the hearts of castrated rats subjected to doxorubicin-induced heart failure. Analyses of serum 17β-estradiol concentrations test confirmed that these effects of testosterone were exerted through the androgen pathway. Thus our findings suggest that testosterone may have beneficial effects for male heart failure patients with androgen deficiency and this protection involves modulation of the cardiac β-adrenergic system.
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Affiliation(s)
- Junfeng Sun
- Department of Cardiovascular Medicine, First Affiliated Hospital, Harbin Medical University, Harbin, China
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The Role of β-adrenergic Receptors in the Cardioprotective Effects of Beta-Preconditioning (βPC). Cardiovasc Drugs Ther 2011; 25:31-46. [DOI: 10.1007/s10557-010-6275-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Barouch LA, Berkowitz DE, Harrison RW, O'Donnell CP, Hare JM. Disruption of leptin signaling contributes to cardiac hypertrophy independently of body weight in mice. Circulation 2003; 108:754-9. [PMID: 12885755 DOI: 10.1161/01.cir.0000083716.82622.fd] [Citation(s) in RCA: 241] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Whether left ventricular hypertrophy (LVH) in obesity results from increased hemodynamic load or altered neurohormonal signaling remains controversial. Dysregulation of leptin, a neurohormone essential to energy homeostasis, is implicated in the pathogenesis of obesity. Because leptin has cardiovascular bioactivity, we hypothesized that disruption of leptin signaling mediates the development of obesity-associated LVH. METHODS AND RESULTS We measured left ventricular (LV) wall thickness and LV mass with echocardiography in mice lacking leptin (ob/ob, n=15) or functional receptor (db/db, n=10) and controls at 2, 4, and 6 months of age. None of the mice had LVH at 2 months. Progressive obesity developed in ob/ob and db/db mice. At 6 months, LVH occurred in ob/ob and db/db compared with controls. We observed corresponding myocyte hypertrophy by light microscopy. To separate the direct contribution of leptin deficiency from mechanical effects of obesity, we induced weight loss in 6- to 8-month-old ob/ob mice either by leptin infusion or caloric restriction. Mice in both groups lost similar weight compared with placebo-treated controls. Leptin infusion completely reversed the increase in wall thickness with partial resolution of myocyte hypertrophy, whereas calorie-restricted mice had no decrease in wall thickness and a lesser change in myocyte size. CONCLUSIONS Together these data show that the effect of leptin on LV remodeling is not attributable to weight loss alone, indicating that leptin has antihypertrophic effects on the heart, either directly or through a leptin-regulated neurohumoral pathway. Disruption of leptin signaling may represent a novel mechanism in LVH and related cardiovascular disorders.
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Affiliation(s)
- Lili A Barouch
- Department of Medicine, Division of Cardiology, Johns Hopkins Hospital, 600 North Wolfe St, Baltimore, Md 21287, USA
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