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Guimaraes DA, Aquino NSS, Rocha-Resende C, Jesus ICG, Silva MM, Scalzo SA, Fonseca RC, Durand MT, Pereira V, Tezini GCSV, Oliveira A, Prado VF, Stefanon I, Salgado HC, Prado MAM, Szawka RE, Guatimosim S. Neuronal cholinergic signaling constrains norepinephrine activity in the heart. Am J Physiol Cell Physiol 2022; 322:C794-C801. [PMID: 35264016 DOI: 10.1152/ajpcell.00031.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is well known that cholinergic hypofunction contributes to cardiac pathology; yet, the mechanisms involved remain unclear. Our previous publication has shown that genetically engineered model of cholinergic deficit, the vesicular acetylcholine transporter knockdown homozygous (VAChT KDHOM) mice exhibit pathological cardiac remodeling and a gradual increase in cardiac mass with aging. Given that an increase in cardiac mass is often caused by adrenergic hyperactivity, we hypothesized that VAChT KDHOM mice might have an increase in cardiac norepinephrine (NE) levels. We thus investigated the temporal changes in NE content in the heart from 3, 6 and 12 month-old VAChT mutants. Interestingly, mice with cholinergic hypofunction showed a gradual elevation in cardiac NE content, which was already increased at 6 months of age. Consistent with this finding, 6 month-old VAChT KDHOM mice showed enhanced sympathetic activity and a greater abundance of tyrosine hydroxylase positive sympathetic nerves in the heart. VAChT mutants exhibited an increase in peak calcium transient, and mitochondrial oxidative stress in cardiomyocytes along with enhanced GRK5 and NFAT staining in the heart. These are known targets of adrenergic signaling in the cell. Moreover, vagotomized-mice displayed an increase in cardiac NE content confirming the data obtained in VAChT KDHOM mice. Establishing a causal relationship between acetylcholine and NE, VAChT KDHOM mice treated with pyridostigmine, a cholinesterase inhibitor, showed reduced cardiac NE content, rescuing the phenotype. Our findings unveil a yet unrecognized role of cholinergic signaling as a modulator of cardiac NE, providing novel insights into the mechanisms that drive autonomic imbalance.
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Affiliation(s)
- Diogo A Guimaraes
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Nayara S S Aquino
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Cibele Rocha-Resende
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Itamar C G Jesus
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Mário Morais Silva
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Sergio A Scalzo
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Roberta Cristelli Fonseca
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Marina T Durand
- Universidade de Ribeirão Preto, Ribeirão Preto, São Paulo, Brazil
| | - Vanessa Pereira
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | | | - André Oliveira
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Vânia F Prado
- Robarts Research Institute, The University of Western Ontario, Department of Physiology 1and Pharmacology, Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Canada
| | - Ivanita Stefanon
- Department of Physiological Sciences, Universidade Federal do Espírito Santo, Vitória, Espirito Santo, Brazil
| | - Helio C Salgado
- Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Marco Antonio Máximo Prado
- Robarts Research Institute, The University of Western Ontario, Department of Physiology 1and Pharmacology, Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Canada
| | - Raphael E Szawka
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Silvia Guatimosim
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
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Janickova H, Kljakic O, Rosborough K, Raulic S, Matovic S, Gros R, Saksida LM, Bussey TJ, Inoue W, Prado VF, Prado MAM. Selective decrease of cholinergic signaling from pedunculopontine and laterodorsal tegmental nuclei has little impact on cognition but markedly increases susceptibility to stress. FASEB J 2019; 33:7018-7036. [PMID: 30857416 DOI: 10.1096/fj.201802108r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The pedunculopontine tegmental nucleus (PPT) and laterodorsal tegmental nucleus (LDT) are heterogeneous brainstem structures that contain cholinergic, glutamatergic, and GABAergic neurons. PPT/LDT neurons are suggested to modulate both cognitive and noncognitive functions, yet the extent to which acetylcholine (ACh) signaling from the PPT/LDT is necessary for normal behavior remains uncertain. We addressed this issue by using a mouse model in which PPT/LDT cholinergic signaling is highly decreased by selective deletion of the vesicular ACh transporter (VAChT) gene. This approach interferes exclusively with ACh signaling, leaving signaling by other neurotransmitters from PPT/LDT cholinergic neurons intact and sparing other cells. VAChT mutants were examined on different PPT/LDT-associated cognitive domains. Interestingly, VAChT mutants showed no attentional deficits and only minor cognitive flexibility impairments while presenting large deficiencies in both spatial and cued Morris water maze (MWM) tasks. Conversely, working spatial memory determined with the Y-maze and spatial memory measured with the Barnes maze were not affected, suggesting that deficits in MWM were unrelated to spatial memory abnormalities. Supporting this interpretation, VAChT mutants exhibited alterations in anxiety-like behavior and increased corticosterone levels after exposure to the MWM, suggesting altered stress response. Thus, PPT/LDT VAChT-mutant mice present little cognitive impairment per se, yet they exhibit increased susceptibility to stress, which may lead to performance deficits in more stressful conditions.-Janickova, H., Kljakic, O., Rosborough, K., Raulic, S., Matovic, S., Gros, R., Saksida, L. M., Bussey, T. J., Inoue, W., Prado, V. F., Prado, M. A. M. Selective decrease of cholinergic signaling from pedunculopontine and laterodorsal tegmental nuclei has little impact on cognition but markedly increases susceptibility to stress.
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Affiliation(s)
- Helena Janickova
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Ornela Kljakic
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Kaie Rosborough
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Sanda Raulic
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Sara Matovic
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada; and
| | - Robert Gros
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada; and
| | - Lisa M Saksida
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada; and.,Brain and Mind Institute, The University of Western Ontario, London, Ontario, Canada
| | - Timothy J Bussey
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada; and.,Brain and Mind Institute, The University of Western Ontario, London, Ontario, Canada
| | - Wataru Inoue
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada; and
| | - Vania F Prado
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada; and.,Brain and Mind Institute, The University of Western Ontario, London, Ontario, Canada
| | - Marco A M Prado
- Robarts Research Institute, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada; and.,Brain and Mind Institute, The University of Western Ontario, London, Ontario, Canada
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Bisphenol A Does Not Mimic Estrogen in the Promotion of the In Vitro Response of Murine Dendritic Cells to Toll-Like Receptor Ligands. Mediators Inflamm 2017; 2017:2034348. [PMID: 28811679 PMCID: PMC5547709 DOI: 10.1155/2017/2034348] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 04/25/2017] [Accepted: 06/05/2017] [Indexed: 11/18/2022] Open
Abstract
Sex hormones affect immune responses and might promote autoimmunity. Endocrine disrupting chemicals such as bisphenol A (BPA) may mimic their immune effects. Conventional dendritic cells (cDCs) are pivotal initiators of immune responses upon activation by danger signals coming from pathogens or distressed tissues through triggering of the Toll-like receptors (TLRs). We generated in vitro murine cDCs in the absence of estrogens and measured the effects of exogenously added estrogen or BPA on their differentiation and activation by the TLR ligands LPS and CpG. Estrogen enhanced the differentiation of GM-CSF-dependent cDCs from bone marrow precursors in vitro, and the selective estrogen receptor modulators (SERMs) tamoxifen and fulvestrant blocked these effects. Moreover, estrogen augmented the upregulation of costimulatory molecules and proinflammatory cytokines (IL-12p70 and TNFα) upon stimulation by TLR9 ligand CpG, while the response to LPS was less estrogen-dependent. These effects are partially explained by an estrogen-dependent regulation of TLR9 expression. BPA did not promote cDC differentiation nor activation upon TLR stimulation. Our results suggest that estrogen promotes immune responses by increasing DC activation, with a preferential effect on TLR9 over TLR4 stimulation, and highlight the influence of estrogens in DC cultures, while BPA does not mimic estrogen in the DC functions that we tested.
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Roy A, Dakroub M, Tezini GCSV, Liu Y, Guatimosim S, Feng Q, Salgado HC, Prado VF, Prado MAM, Gros R. Cardiac acetylcholine inhibits ventricular remodeling and dysfunction under pathologic conditions. FASEB J 2015; 30:688-701. [PMID: 26481308 DOI: 10.1096/fj.15-277046] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/28/2015] [Indexed: 12/11/2022]
Abstract
Autonomic dysfunction is a characteristic of cardiac disease and decreased vagal activity is observed in heart failure. Rodent cardiomyocytes produce de novo ACh, which is critical in maintaining cardiac homeostasis. We report that this nonneuronal cholinergic system is also found in human cardiomyocytes, which expressed choline acetyltransferase (ChAT) and the vesicular acetylcholine transporter (VAChT). Furthermore, VAChT expression was increased 3- and 1.5-fold at the mRNA and protein level, respectively, in ventricular tissue from patients with heart failure, suggesting increased ACh secretion in disease. We used mice with genetic deletion of cardiomyocyte-specific VAChT or ChAT and mice overexpressing VAChT to test the functional significance of cholinergic signaling. Mice deficient for VAChT displayed an 8% decrease in fractional shortening and 13% decrease in ejection fraction compared with angiotensin II (Ang II)-treated control animals, suggesting enhanced ventricular dysfunction and pathologic remodeling in response to Ang II. Similar results were observed in ChAT-deficient mice. Conversely, no decline in ventricular function was observed in Ang II-treated VAChT overexpressors. Furthermore, the fibrotic area was significantly greater (P < 0.05) in Ang II-treated VAChT-deficient mice (3.61 ± 0.64%) compared with wild-type animals (2.24 ± 0.11%). In contrast, VAChT overexpressing mice did not display an increase in collagen deposition. Our results provide new insight into cholinergic regulation of cardiac function, suggesting that a compensatory increase in cardiomyocyte VAChT levels may help offset cardiac remodeling in heart failure.
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Affiliation(s)
- Ashbeel Roy
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Mouhamed Dakroub
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Geisa C S V Tezini
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Yin Liu
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Silvia Guatimosim
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Qingping Feng
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Helio C Salgado
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Vania F Prado
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Marco A M Prado
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Robert Gros
- *Robarts Research Institute, Department of Physiology and Pharmacology, Department of Medicine, and Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada; Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
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Roy A, Guatimosim S, Prado VF, Gros R, Prado MAM. Cholinergic activity as a new target in diseases of the heart. Mol Med 2015; 20:527-37. [PMID: 25222914 DOI: 10.2119/molmed.2014.00125] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 09/09/2014] [Indexed: 12/21/2022] Open
Abstract
The autonomic nervous system is an important modulator of cardiac signaling in both health and disease. In fact, the significance of altered parasympathetic tone in cardiac disease has recently come to the forefront. Both neuronal and nonneuronal cholinergic signaling likely play a physiological role, since modulating acetylcholine (ACh) signaling from neurons or cardiomyocytes appears to have significant consequences in both health and disease. Notably, many of these effects are solely due to changes in cholinergic signaling, without altered sympathetic drive, which is known to have significant adverse effects in disease states. As such, it is likely that enhanced ACh-mediated signaling not only has direct positive effects on cardiomyocytes, but it also offsets the negative effects of hyperadrenergic tone. In this review, we discuss recent studies that implicate ACh as a major regulator of cardiac remodeling and provide support for the notion that enhancing cholinergic signaling in human patients with cardiac disease can reduce morbidity and mortality. These recent results support the idea of developing large clinical trials of strategies to increase cholinergic tone, either by stimulating the vagus or by increased availability of Ach, in heart failure.
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Affiliation(s)
- Ashbeel Roy
- Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada
| | - Silvia Guatimosim
- Department of Physiology and Biophysics, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Vania F Prado
- Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada
| | - Robert Gros
- Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada.,Department of Medicine, University of Western Ontario, London, Ontario, Canada
| | - Marco A M Prado
- Robarts Research Institute, The University of Western Ontario, London, Ontario, Canada.,Department of Physiology and Pharmacology, The University of Western Ontario, London, Ontario, Canada.,Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada
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Yang S, Chen L, Sun S, Shah P, Yang W, Zhang B, Zhang Z, Chan DW, Kass DA, van Eyk JE, Zhang H. Glycoproteins identified from heart failure and treatment models. Proteomics 2014; 15:567-79. [PMID: 25141849 DOI: 10.1002/pmic.201400151] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 07/28/2014] [Accepted: 08/15/2014] [Indexed: 01/12/2023]
Abstract
Conduction abnormalities can lead to dyssynchronous contraction, which significantly worsens morbidity and mortality of heart failure. Cardiac resynchronization therapy (CRT) can reverse ventricular remodeling and improve cardiac function. Although the underlying molecular changes are unknown, the use of a canine model of dyssynchronous heart failure (DHF) and CRT has shown that there are global changes across the cardiac proteome. This study determines changes in serum glycoprotein concentration from DHF and CRT compared to normal. We hypothesize that CRT invokes protective or advantageous pathways that can be reflected in the circulating proteome. Two prong discovery approaches were carried out on pooled normal, DHF, and CRT samples composed of individual canine serum to determine the overall protein concentration and the N-linked glycosites of circulating glycoproteins. The level of the glycoproteins was altered in DHF and CRT compared to control sera, with 63 glycopeptides substantially increased in DHF and/or CRT. Among the 32 elevated glycosite-containing peptides in DHF, 13 glycopeptides were reverted to normal level after CRT therapy. We further verify the changes of glycopeptides using label-free LC-MS from individual canine serum. Circulating glycoproteins such as alpha-fetoprotein, alpha-2-macroglobulin, galectin-3-binding protein, and collectin-10 show association to failing heart and CRT treatment model.
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Affiliation(s)
- Shuang Yang
- Department of Pathology, Johns Hopkins University, Baltimore, MD, USA
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Roy A, Fields WC, Rocha-Resende C, Resende RR, Guatimosim S, Prado VF, Gros R, Prado MAM. Cardiomyocyte-secreted acetylcholine is required for maintenance of homeostasis in the heart. FASEB J 2013; 27:5072-82. [PMID: 24018063 DOI: 10.1096/fj.13-238279] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Heart activity and long-term function are regulated by the sympathetic and parasympathetic branches of the nervous system. Parasympathetic neurons have received increased attention recently because acetylcholine (ACh) has been shown to play protective roles in heart disease. However, parasympathetic innervation is sparse in the heart, raising the question of how cholinergic signaling regulates cardiomyocytes. We hypothesized that non-neuronal secretion of ACh from cardiomyocytes plays a role in cholinergic regulation of cardiac activity. To test this possibility, we eliminated secretion of ACh exclusively from cardiomyocytes by targeting the vesicular acetylcholine transporter (VAChT). We find that lack of cardiomyocyte-secreted ACh disturbs the regulation of cardiac activity and causes cardiomyocyte remodeling. Mutant mice present normal hemodynamic parameters under nonstressful conditions; however, following exercise, their heart rate response is increased. Moreover, hearts from mutant mice present increased oxidative stress, altered calcium signaling, remodeling, and hypertrophy. Hence, without cardiomyocyte-derived ACh secretion, hearts from mutant mice show signs of imbalanced autonomic activity consistent with decreased cholinergic drive. These unexpected results suggest that cardiomyocyte-derived ACh is required for maintenance of cardiac homeostasis and regulates critical signaling pathways necessary to maintain normal heart activity. We propose that this non-neuronal source of ACh boosts parasympathetic cholinergic signaling to counterbalance sympathetic activity regulating multiple aspects of heart physiology.
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Affiliation(s)
- Ashbeel Roy
- 1Robarts Research Institute, 100 Perth Dr., London, Ontario, N6A 5K8, Canada. M.A.M.P.,
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ChAT-ChR2-EYFP mice have enhanced motor endurance but show deficits in attention and several additional cognitive domains. J Neurosci 2013; 33:10427-38. [PMID: 23785154 DOI: 10.1523/jneurosci.0395-13.2013] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Acetylcholine (ACh) is an important neuromodulator in the nervous system implicated in many forms of cognitive and motor processing. Recent studies have used bacterial artificial chromosome (BAC) transgenic mice expressing channelrhodopsin-2 (ChR2) protein under the control of the choline acetyltransferase (ChAT) promoter (ChAT-ChR2-EYFP) to dissect cholinergic circuit connectivity and function using optogenetic approaches. We report that a mouse line used for this purpose also carries several copies of the vesicular acetylcholine transporter gene (VAChT), which leads to overexpression of functional VAChT and consequently increased cholinergic tone. We demonstrate that these mice have marked improvement in motor endurance. However, they also present severe cognitive deficits, including attention deficits and dysfunction in working memory and spatial memory. These results suggest that increased VAChT expression may disrupt critical steps in information processing. Our studies demonstrate that ChAT-ChR2-EYFP mice show altered cholinergic tone that fundamentally differentiates them from wild-type mice.
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Abstract
Acetylcholine, the first chemical to be identified as a neurotransmitter, is packed in synaptic vesicles by the activity of VAChT (vesicular acetylcholine transporter). A decrease in VAChT expression has been reported in a number of diseases, and this has consequences for the amount of acetylcholine loaded in synaptic vesicles as well as for neurotransmitter release. Several genetically modified mice targeting the VAChT gene have been generated, providing novel models to understand how changes in VAChT affect transmitter release. A surprising finding is that most cholinergic neurons in the brain also can express a second type of vesicular neurotransmitter transporter that allows these neurons to secrete two distinct neurotransmitters. Thus a given neuron can use two neurotransmitters to regulate different physiological functions. In addition, recent data indicate that non-neuronal cells can also express the machinery used to synthesize and release acetylcholine. Some of these cells rely on VAChT to secrete acetylcholine with potential physiological consequences in the periphery. Hence novel functions for the oldest neurotransmitter known are emerging with the potential to provide new targets for the treatment of several pathological conditions.
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