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Mukai Y, Nagayama A, Itoi K, Yamanaka A. Identification of substances which regulate activity of corticotropin-releasing factor-producing neurons in the paraventricular nucleus of the hypothalamus. Sci Rep 2020; 10:13639. [PMID: 32788592 PMCID: PMC7424526 DOI: 10.1038/s41598-020-70481-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 07/30/2020] [Indexed: 12/24/2022] Open
Abstract
The stress response is a physiological system for adapting to various internal and external stimuli. Corticotropin-releasing factor-producing neurons in the paraventricular nucleus of the hypothalamus (PVN-CRF neurons) are known to play an important role in the stress response as initiators of the hypothalamic-pituitary-adrenal axis. However, the mechanism by which activity of PVN-CRF neurons is regulated by other neurons and bioactive substances remains unclear. Here, we developed a screening method using calcium imaging to identify how physiological substances directly affect the activity of PVN-CRF neurons. We used acute brain slices expressing a genetically encoded calcium indicator in PVN-CRF neurons using CRF-Cre recombinase mice and an adeno-associated viral vector under Cre control. PVN-CRF neurons were divided into ventral and dorsal portions. Bath application of candidate substances revealed 12 substances that increased and 3 that decreased intracellular calcium concentrations. Among these substances, angiotensin II and histamine mainly increased calcium in the ventral portion of the PVN-CRF neurons via AT1 and H1 receptors, respectively. Conversely, carbachol mainly increased calcium in the dorsal portion of the PVN-CRF neurons via both nicotinic and muscarinic acetylcholine receptors. Our method provides a precise and reliable means of evaluating the effect of a substance on PVN-CRF neuronal activity.
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Affiliation(s)
- Yasutaka Mukai
- Department of Neuroscience II, Research Institute of Environmental Medicine, Nagoya University, Nagoya, 464-8601, Japan.,Department of Neural Regulation, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan.,CREST, JST, Honcho, Kawaguchi, Saitama, 332-0012, Japan.,JSPS Research Fellowship for Young Scientists, Tokyo, 102-0083, Japan
| | - Ayako Nagayama
- Department of Neuroscience II, Research Institute of Environmental Medicine, Nagoya University, Nagoya, 464-8601, Japan.,Department of Neural Regulation, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Keiichi Itoi
- Department of Neuroendocrinology, Graduate School of Medicine, Tohoku University, Sendai, 980-8575, Japan
| | - Akihiro Yamanaka
- Department of Neuroscience II, Research Institute of Environmental Medicine, Nagoya University, Nagoya, 464-8601, Japan. .,Department of Neural Regulation, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan. .,CREST, JST, Honcho, Kawaguchi, Saitama, 332-0012, Japan.
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2
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Gao HR, Gao HY. Cardiovascular functions of central corticotropin-releasing factor related peptides system. Neuropeptides 2019; 75:18-24. [PMID: 30922523 DOI: 10.1016/j.npep.2019.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 02/26/2019] [Accepted: 03/19/2019] [Indexed: 10/27/2022]
Abstract
The corticotropin-releasing factor (CRF) related peptides system has widespread distributions in central nervous system, to perform many physiological and pathophysiological functions, including cardiovascular functions. A complex connection exists between the central CRF related peptides system and cardiovascular system. There are multiple pathways and mechanisms through which the central CRF related peptides system influences cardiovascular functions. A dysfunction in the central CRF related peptides system may lead to a wide range of alterations in cardiovascular functions. Though there are difficulties or limitations in establishing exact modulatory roles of the central CRF related peptides system in cardiovascular functions. The central CRF related peptides system as target to prevent cardiovascular diseases is being pursued with increasing interest. In this review, we summarize recent understanding on cardiovascular functions of the CRF related peptides system in limbic forebrain, hypothalamus and brain stem structures, discuss mechanisms of the central CRF related peptides system in control of cardiovascular functions, and suggest that the central CRF related peptides system may be a potent candidate for prevention of cardiovascular diseases.
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Affiliation(s)
- He-Ren Gao
- Research Institute of Acupuncture and Meridian, Anhui University of Chinese Medicine, Hefei 230038, China.
| | - He-Yuan Gao
- Department of Pediatrics, The First Hospital of Qinhuangdao, Qinhuangdao, Hebei 066000, China
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3
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Vierra NC, Dickerson MT, Jordan KL, Dadi PK, Katdare KA, Altman MK, Milian SC, Jacobson DA. TALK-1 reduces delta-cell endoplasmic reticulum and cytoplasmic calcium levels limiting somatostatin secretion. Mol Metab 2018; 9:84-97. [PMID: 29402588 PMCID: PMC5870147 DOI: 10.1016/j.molmet.2018.01.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 01/19/2018] [Indexed: 01/17/2023] Open
Abstract
OBJECTIVE Single-cell RNA sequencing studies have revealed that the type-2 diabetes associated two-pore domain K+ (K2P) channel TALK-1 is abundantly expressed in somatostatin-secreting δ-cells. However, a physiological role for TALK-1 in δ-cells remains unknown. We previously determined that in β-cells, K+ flux through endoplasmic reticulum (ER)-localized TALK-1 channels enhances ER Ca2+ leak, modulating Ca2+ handling and insulin secretion. As glucose amplification of islet somatostatin release relies on Ca2+-induced Ca2+ release (CICR) from the δ-cell ER, we investigated whether TALK-1 modulates δ-cell Ca2+ handling and somatostatin secretion. METHODS To define the functions of islet δ-cell TALK-1 channels, we generated control and TALK-1 channel-deficient (TALK-1 KO) mice expressing fluorescent reporters specifically in δ- and α-cells to facilitate cell type identification. Using immunofluorescence, patch clamp electrophysiology, Ca2+ imaging, and hormone secretion assays, we assessed how TALK-1 channel activity impacts δ- and α-cell function. RESULTS TALK-1 channels are expressed in both mouse and human δ-cells, where they modulate glucose-stimulated changes in cytosolic Ca2+ and somatostatin secretion. Measurement of cytosolic Ca2+ levels in response to membrane potential depolarization revealed enhanced CICR in TALK-1 KO δ-cells that could be abolished by depleting ER Ca2+ with sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) inhibitors. Consistent with elevated somatostatin inhibitory tone, we observed significantly reduced glucagon secretion and α-cell Ca2+ oscillations in TALK-1 KO islets, and found that blockade of α-cell somatostatin signaling with a somatostatin receptor 2 (SSTR2) antagonist restored glucagon secretion in TALK-1 KO islets. CONCLUSIONS These data indicate that TALK-1 reduces δ-cell cytosolic Ca2+ elevations and somatostatin release by limiting δ-cell CICR, modulating the intraislet paracrine signaling mechanisms that control glucagon secretion.
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Affiliation(s)
- Nicholas C Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Kelli L Jordan
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Ketaki A Katdare
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Molly K Altman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Sarah C Milian
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
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Brailoiu E, McGuire M, Shuler SA, Deliu E, Barr JL, Abood ME, Brailoiu GC. Modulation of cardiac vagal tone by bradykinin acting on nucleus ambiguus. Neuroscience 2017; 365:23-32. [PMID: 28951324 DOI: 10.1016/j.neuroscience.2017.09.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 09/11/2017] [Accepted: 09/18/2017] [Indexed: 12/21/2022]
Abstract
Bradykinin (BK), a component of the kallikrein-kininogen-kinin system exerts multiple effects via B1 and B2 receptor activation. In the cardiovascular system, bradykinin has cardioprotective and vasodilator properties. We investigated the effect of BK on cardiac-projecting neurons of nucleus ambiguus, a key site for the parasympathetic cardiac regulation. BK produced a dose-dependent increase in cytosolic Ca2+ concentration. Pretreatment with HOE140, a B2 receptor antagonist, but not with R715, a B1 receptor antagonist, abolished the response to BK. A selective B2 receptor agonist, but not a B1 receptor agonist, elicited an increase in cytosolic Ca2+ similarly to BK. Inhibition of N-type voltage-gated Ca2+ channels with ω-conotoxin GVIA had no effect on the Ca2+ signal produced by BK, while pretreatment with ω-conotoxin MVIIC, a blocker of P/Q-type of Ca2+ channels, significantly diminished the effect of BK. Pretreatment with xestospongin C and 2-aminoethoxydiphenyl borate, antagonists of inositol 1,4,5-trisphosphate receptors, abolished the response to BK. Inhibition of ryanodine receptors reduced the BK-induced Ca2+ increase, while disruption of lysosomal Ca2+ stores with bafilomycin A1 did not affect the response. BK produced a dose-dependent depolarization of nucleus ambiguus neurons, which was prevented by the B2 receptor antagonist. In vivo studies indicate that microinjection of BK into nucleus ambiguus elicited bradycardia in conscious rats via B2 receptors. In summary, in cardiac vagal neurons of nucleus ambiguus, BK activates B2 receptors promoting Ca2+ influx and Ca2+ release from endoplasmic reticulum, and membrane depolarization; these effects are translated in vivo by bradycardia.
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Affiliation(s)
- Eugen Brailoiu
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Philadelphia, PA 19140, United States
| | - Matthew McGuire
- Department of Pharmaceutical Sciences, Jefferson College of Pharmacy, Philadelphia, PA 19107, United States
| | - Shadaria A Shuler
- Department of Pharmaceutical Sciences, Jefferson College of Pharmacy, Philadelphia, PA 19107, United States
| | - Elena Deliu
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Philadelphia, PA 19140, United States
| | - Jeffrey L Barr
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Philadelphia, PA 19140, United States
| | - Mary E Abood
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Philadelphia, PA 19140, United States
| | - G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Jefferson College of Pharmacy, Philadelphia, PA 19107, United States.
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5
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Tan LA, Vaughan JM, Perrin MH, Rivier JE, Sawchenko PE. Distribution of corticotropin-releasing factor (CRF) receptor binding in the mouse brain using a new, high-affinity radioligand, [125I]-PD-Sauvagine. J Comp Neurol 2017; 525:3840-3864. [DOI: 10.1002/cne.24307] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 08/15/2017] [Accepted: 08/16/2017] [Indexed: 01/30/2023]
Affiliation(s)
- Laura A. Tan
- Laboratory of Neuronal Structure and Function; The Salk Institute for Biological Studies; La Jolla CA
| | - Joan M. Vaughan
- Laboratory of Neuronal Structure and Function; The Salk Institute for Biological Studies; La Jolla CA
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies; La Jolla CA
| | - Marilyn H. Perrin
- Laboratory of Neuronal Structure and Function; The Salk Institute for Biological Studies; La Jolla CA
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies; La Jolla CA
| | - Jean E. Rivier
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies; La Jolla CA
| | - Paul E. Sawchenko
- Laboratory of Neuronal Structure and Function; The Salk Institute for Biological Studies; La Jolla CA
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6
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Ayyadurai S, Gibson AJ, D'Costa S, Overman EL, Sommerville LJ, Poopal AC, Mackey E, Li Y, Moeser AJ. Frontline Science: Corticotropin-releasing factor receptor subtype 1 is a critical modulator of mast cell degranulation and stress-induced pathophysiology. J Leukoc Biol 2017; 102:1299-1312. [PMID: 28684600 DOI: 10.1189/jlb.2hi0317-088rr] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/28/2017] [Accepted: 06/05/2017] [Indexed: 12/23/2022] Open
Abstract
Life stress is a major risk factor in the onset and exacerbation of mast cell-associated diseases, including allergy/anaphylaxis, asthma, and irritable bowel syndrome. Although it is known that mast cells are highly activated upon stressful events, the mechanisms by which stress modulates mast cell function and disease pathophysiology remains poorly understood. Here, we investigated the role of corticotropin-releasing factor receptor subtype 1 (CRF1) in mast cell degranulation and associated disease pathophysiology. In a mast cell-dependent model of IgE-mediated passive systemic anaphylaxis (PSA), prophylactic administration of the CRF1-antagonist antalarmin attenuated mast cell degranulation and hypothermia. Mast cell-deficient KitW-sh/W-sh mice engrafted with CRF1-/- bone marrow-derived mast cells (BMMCs) exhibited attenuated PSA-induced serum histamine, hypothermia, and clinical scores compared with wild-type BMMC-engrafted KitW-sh/W-sh mice. KitW-sh/W-sh mice engrafted with CRF1-/- BMMCs also exhibited suppressed in vivo mast cell degranulation and intestinal permeability in response to acute restraint stress. Genetic and pharmacologic experiments with murine BMMCs, rat RBL-2H3, and human LAD2 mast cells demonstrated that although CRF1 activation did not directly induce MC degranulation, CRF1 signaling potentiated the degranulation responses triggered by diverse mast cell stimuli and was associated with enhanced release of Ca2+ from intracellular stores. Taken together, our results revealed a prominent role for CRF1 signaling in mast cells as a positive modulator of stimuli-induced degranulation and in vivo pathophysiologic responses to immunologic and psychologic stress.
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Affiliation(s)
- Saravanan Ayyadurai
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | | | - Susan D'Costa
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Elizabeth L Overman
- Department of Biology, Methodist University, Fayetteville, North Carolina, USA
| | - Laura J Sommerville
- Department of Pathology, Duke University, School of Medicine, Durham, North Carolina, USA
| | - Ashwini C Poopal
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Emily Mackey
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA.,Comparative Biomedical Sciences Graduate Program, North Carolina State University, Raleigh, North Carolina, USA
| | - Yihang Li
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Adam J Moeser
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA; .,Neuroscience Program, Michigan State University, East Lansing, Michigan, USA; and.,Department of Physiology, Michigan State University, East Lansing, Michigan, USA
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7
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Gherghina FL, Tica AA, Deliu E, Abood ME, Brailoiu GC, Brailoiu E. Effects of VPAC1 activation in nucleus ambiguus neurons. Brain Res 2017; 1657:297-303. [PMID: 28043808 DOI: 10.1016/j.brainres.2016.12.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 12/20/2016] [Accepted: 12/27/2016] [Indexed: 11/25/2022]
Abstract
The pituitary adenylyl cyclase-activating polypeptide (PACAP) and its G protein-coupled receptors, PAC1, VPAC1 and VPAC2 form a system involved in a variety of biological processes. Although some sympathetic stimulatory effects of this system have been reported, its central cardiovascular regulatory properties are poorly characterized. VPAC1 receptors are expressed in the nucleus ambiguus (nAmb), a key center controlling cardiac parasympathetic tone. In this study, we report that selective VPAC1 activation in rhodamine-labeled cardiac vagal preganglionic neurons of the rat nAmb produces inositol 1,4,5-trisphosphate receptor-mediated Ca2+ mobilization, membrane depolarization and activation of P/Q-type Ca2+ channels. In vivo, this pathway converges onto transient reduction in heart rate of conscious rats. Therefore we demonstrate a VPAC1-dependent mechanism in the central parasympathetic regulation of the heart rate, adding to the complexity of PACAP-mediated cardiovascular modulation.
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Affiliation(s)
| | - Andrei Adrian Tica
- Department of Pharmacology, University of Medicine and Pharmacy, Craiova, Romania
| | - Elena Deliu
- Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Mary E Abood
- Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA 19140, USA; Department of Anatomy and Cell Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Thomas Jefferson University, Jefferson College of Pharmacy, Philadelphia, PA 19107, USA
| | - Eugen Brailoiu
- Center for Substance Abuse Research, Temple University School of Medicine, Philadelphia, PA 19140, USA.
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Dyavanapalli J, Dergacheva O, Wang X, Mendelowitz D. Parasympathetic Vagal Control of Cardiac Function. Curr Hypertens Rep 2016; 18:22. [PMID: 26849575 DOI: 10.1007/s11906-016-0630-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This brief review focuses on four new topics, with novel and clinically significant consequences, concerning the powerful influence of parasympathetic activity on cardiac function. In this short summary, we will highlight very recent and important work, published in the last 3-4 years, that (1) challenges the paradigm that parasympathetic activity to the heart is involved in the control of heart rate but plays little role in other cardiac functions, (2) characterizes important long-range synaptic pathways to parasympathetic cardiac vagal neurons that are involved in "higher" brain functions (such as arousal and emotional challenges), (3) asks whether implantable chronic vagal nerve stimulation is a promising clinical tool for treating cardiovascular diseases, and (4) describes newly identified neuropeptides and other modulators that can influence the generation and maintenance of parasympathetic activity to the heart.
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Affiliation(s)
- Jhansi Dyavanapalli
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA
| | - Olga Dergacheva
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA
| | - Xin Wang
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA
| | - David Mendelowitz
- Department of Pharmacology and Physiology, The George Washington University, 2300 Eye St NW, Washington, DC, 20037, USA.
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Brailoiu E, Deliu E, Sporici RA, Benamar K, Brailoiu GC. HIV-1-Tat excites cardiac parasympathetic neurons of nucleus ambiguus and triggers prolonged bradycardia in conscious rats. Am J Physiol Regul Integr Comp Physiol 2014; 306:R814-22. [PMID: 24694382 DOI: 10.1152/ajpregu.00529.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The mechanisms of autonomic imbalance and subsequent cardiovascular manifestations in HIV-1-infected patients are poorly understood. We report here that HIV-1 transactivator of transcription (Tat, fragment 1-86) produced a concentration-dependent increase in cytosolic Ca(2+) in cardiac-projecting parasympathetic neurons of nucleus ambiguus retrogradely labeled with rhodamine. Using store-specific pharmacological agents, we identified several mechanisms of the Tat-induced Ca(2+) elevation: 1) lysosomal Ca(2+) mobilization, 2) Ca(2+) release via inositol 1,4,5-trisphosphate-sensitive endoplasmic reticulum pools, and 3) Ca(2+) influx via transient receptor potential vanilloid type 2 (TRPV2) channels. Activation of TRPV2, nonselective cation channels, induced a robust and prolonged neuronal membrane depolarization, thus triggering an additional P/Q-mediated Ca(2+) entry. In vivo microinjection studies indicate a dose-dependent, prolonged bradycardic effect of Tat administration into the nucleus ambiguus of conscious rats, in which neuronal TRPV2 played a major role. Our results support previous studies, indicating that Tat promotes bradycardia and, consequently, may be involved in the QT interval prolongation reported in HIV-infected patients. In the context of an overall HIV-dependent autonomic dysfunction, these Tat-mediated mechanisms may account for the higher prevalence of sudden cardiac death in HIV-1-infected patients compared with general population with similar risk factors. Our results may be particularly relevant in view of the recent findings that significant Tat levels can still be identified in the cerebrospinal fluid of HIV-infected patients with viral load suppression due to efficient antiretroviral therapy.
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Affiliation(s)
- Eugen Brailoiu
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania; Center for Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Elena Deliu
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Romeo A Sporici
- Department of Internal Medicine, Brandywine Hospital, Coatesville, Pennsylvania
| | - Khalid Benamar
- Center for Substance Abuse, Temple University School of Medicine, Philadelphia, Pennsylvania; and
| | - G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Thomas Jefferson University, Jefferson School of Pharmacy, Philadelphia, Pennsylvania
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10
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Brailoiu GC, Deliu E, Rabinowitz JE, Tilley DG, Koch WJ, Brailoiu E. Urotensin II promotes vagal-mediated bradycardia by activating cardiac-projecting parasympathetic neurons of nucleus ambiguus. J Neurochem 2014; 129:628-36. [PMID: 24521102 DOI: 10.1111/jnc.12679] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/31/2014] [Accepted: 02/05/2014] [Indexed: 12/31/2022]
Abstract
Urotensin II (U-II) is a cyclic undecapeptide that regulates cardiovascular function at central and peripheral sites. The functional role of U-II nucleus ambiguus, a key site controlling cardiac tone, has not been established, despite the identification of U-II and its receptor at this level. We report here that U-II produces an increase in cytosolic Ca(2+) concentration in retrogradely labeled cardiac vagal neurons of nucleus ambiguus via two pathways: (i) Ca(2+) release from the endoplasmic reticulum via inositol 1,4,5-trisphosphate receptor; and (ii) Ca(2+) influx through P/Q-type Ca(2+) channels. In addition, U-II depolarizes cultured cardiac parasympathetic neurons. Microinjection of increasing concentrations of U-II into nucleus ambiguus elicits dose-dependent bradycardia in conscious rats, indicating the in vivo activation of the cholinergic pathway controlling the heart rate. Both the in vitro and in vivo effects were abolished by the urotensin receptor antagonist, urantide. Our findings suggest that, in addition, to the previously reported increase in sympathetic outflow, U-II activates cardiac vagal neurons of nucleus ambiguus, which may contribute to cardioprotection.
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Affiliation(s)
- Gabriela Cristina Brailoiu
- Department of Pharmaceutical Sciences, Thomas Jefferson University, Jefferson School of Pharmacy, Philadelphia, Pennsylvania, USA
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11
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Brailoiu GC, Benamar K, Arterburn JB, Gao E, Rabinowitz JE, Koch WJ, Brailoiu E. Aldosterone increases cardiac vagal tone via G protein-coupled oestrogen receptor activation. J Physiol 2013; 591:4223-35. [PMID: 23878371 DOI: 10.1113/jphysiol.2013.257204] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In addition to acting on mineralocorticoid receptors, aldosterone has been recently shown to activate the G protein-coupled oestrogen receptor (GPER) in vascular cells. In light of the newly identified role for GPER in vagal cardiac control, we examined whether or not aldosterone activates GPER in rat nucleus ambiguus. Aldosterone produced a dose-dependent increase in cytosolic Ca(2+) concentration in retrogradely labelled cardiac vagal neurons of nucleus ambiguus; the response was abolished by pretreatment with the GPER antagonist G-36, but was not affected by the mineralocorticoid receptor antagonists, spironolactone and eplerenone. In Ca(2+)-free saline, the response to aldosterone was insensitive to blockade of the Ca(2+) release from lysosomes, while it was reduced by blocking the Ca(2+) release via ryanodine receptors and abolished by blocking the IP3 receptors. Aldosterone induced Ca(2+) influx via P/Q-type Ca(2+) channels, but not via L-type and N-type Ca(2+) channels. Aldosterone induced depolarization of cardiac vagal neurons of nucleus ambiguus that was sensitive to antagonism of GPER but not of mineralocorticoid receptor. in vivo studies, using telemetric measurement of heart rate, indicate that microinjection of aldosterone into the nucleus ambiguus produced a dose-dependent bradycardia in conscious, freely moving rats. Aldosterone-induced bradycardia was blocked by the GPER antagonist, but not by the mineralocorticoid receptor antagonists. In summary, we report for the first time that aldosterone decreases heart rate by activating GPER in cardiac vagal neurons of nucleus ambiguus.
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Affiliation(s)
- G Cristina Brailoiu
- E. Brailoiu: Center for Translational Medicine, Temple University School of Medicine, MERB, 3500 N. Broad Street, Philadelphia, PA 19140, USA.
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12
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Brailoiu GC, Deliu E, Tica AA, Rabinowitz JE, Tilley DG, Benamar K, Koch WJ, Brailoiu E. Nesfatin-1 activates cardiac vagal neurons of nucleus ambiguus and elicits bradycardia in conscious rats. J Neurochem 2013; 126:739-48. [PMID: 23795642 DOI: 10.1111/jnc.12355] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 05/12/2013] [Accepted: 06/20/2013] [Indexed: 11/30/2022]
Abstract
Nesfatin-1, a peptide whose receptor is yet to be identified, has been involved in the modulation of feeding, stress, and metabolic responses. More recently, increasing evidence supports a modulatory role for nesfatin-1 in autonomic and cardiovascular activity. This study was undertaken to test if the expression of nesfatin-1 in the nucleus ambiguus, a key site for parasympathetic cardiac control, may be correlated with a functional role. As we have previously demonstrated that nesfatin-1 elicits Ca²⁺ signaling in hypothalamic neurons, we first assessed the effect of this peptide on cytosolic Ca²⁺ in cardiac pre-ganglionic neurons of nucleus ambiguus. We provide evidence that nesfatin-1 increases cytosolic Ca²⁺ concentration via a Gi/o-coupled mechanism. The nesfatin-1-induced Ca²⁺ rise is critically dependent on Ca²⁺ influx via P/Q-type voltage-activated Ca²⁺ channels. Repeated administration of nesfatin-1 leads to tachyphylaxis. Furthermore, nesfatin-1 produces a dose-dependent depolarization of cardiac vagal neurons via a Gi/o-coupled mechanism. In vivo studies, using telemetric and tail-cuff monitoring of heart rate and blood pressure, indicate that microinjection of nesfatin-1 into the nucleus ambiguus produces bradycardia not accompanied by a change in blood pressure in conscious rats. Taken together, our results identify for the first time that nesfatin-1 decreases heart rate by activating cardiac vagal neurons of nucleus ambiguus. Our results indicate that nesfatin-1, one of the most potent feeding peptides, increases cytosolic Ca²⁺ by promoting Ca²⁺ influx via P/Q channels and depolarizes nucleus ambiguus neurons; both effects are Gi/o-mediated. In vivo studies indicate that microinjection of nesfatin-1 into nucleus ambiguus produces bradycardia in conscious rats. This is the first report that nesfatin-1 increases the parasympathetic cardiac tone.
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Affiliation(s)
- G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Thomas Jefferson University, Jefferson School of Pharmacy, Philadelphia, Pennsylvania, USA
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Gellerich FN, Gizatullina Z, Gainutdinov T, Muth K, Seppet E, Orynbayeva Z, Vielhaber S. The control of brain mitochondrial energization by cytosolic calcium: the mitochondrial gas pedal. IUBMB Life 2013; 65:180-90. [PMID: 23401251 DOI: 10.1002/iub.1131] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 12/08/2012] [Indexed: 11/05/2022]
Abstract
This review focuses on problems of the intracellular regulation of mitochondrial function in the brain via the (i) supply of mitochondria with ADP by means of ADP shuttles and channels and (ii) the Ca(2+) control of mitochondrial substrate supply. The permeability of the mitochondrial outer membrane for adenine nucleotides is low. Therefore rate dependent concentration gradients exist between the mitochondrial intermembrane space and the cytosol. The existence of dynamic ADP gradients is an important precondition for the functioning of ADP shuttles, for example CrP-shuttle. Cr at mM concentrations instead of ADP diffuses from the cytosol through the porin pores into the intermembrane space. The CrP-shuttle isoenzymes work in different directions which requires different metabolite concentrations mainly caused by dynamic ADP compartmentation. The ADP shuttle mechanisms alone cannot explain the load dependent changes in mitochondrial energization, and a complete model of mitochondrial regulation have to account the Ca(2+) -dependent substrate supply too. According to the old paradigmatic view, Ca(2+) (cyt) taken up by the mitochondrial Ca(2+) uniporter activates dehydrogenases within the matrix. However, recently it was found that Ca(2+) (cyt) at low nM concentrations exclusively activates the state 3 respiration via aralar, the mitochondrial glutamate/aspartate carrier. At higher Ca(2+) (cyt) (> 500 nM), brain mitochondria take up Ca(2+) for activation of substrate oxidation rates. Since brain mitochondrial pyruvate oxidation is only slightly influenced by Ca(2+) (cyt) , it was proposed that the cytosolic formation of pyruvate from its precursors is tightly controlled by the Ca(2+) dependent malate/aspartate shuttle. At low (50-100 nM) Ca(2+) (cyt) the pyruvate formation is suppressed, providing a substrate limitation control in neurons. This so called "gas pedal" mechanism explains why the energy metabolism of neurons in the nucleus suprachiasmaticus could be down-regulated at night but activated at day as a basis for the circadian changes in Ca(2+) (cyt) . It also could explain the energetic disadvantages caused by altered Ca(2+) (cyt) at mitochondrial diseases and neurodegeneration.
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Affiliation(s)
- Frank Norbert Gellerich
- Leibniz Institute for Neurobiology Magdeburg, Department of Behavioral Neurology, 39118 Magdeburg, Germany.
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Brailoiu GC, Arterburn JB, Oprea TI, Chitravanshi VC, Brailoiu E. Bradycardic effects mediated by activation of G protein-coupled estrogen receptor in rat nucleus ambiguus. Exp Physiol 2012; 98:679-91. [PMID: 23104934 DOI: 10.1113/expphysiol.2012.069377] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The G protein-coupled estrogen receptor (GPER) has been identified in several brain regions, including cholinergic neurons of the nucleus ambiguus, which are critical for parasympathetic cardiac regulation. Using calcium imaging and electrophysiological techniques, microinjection into the nucleus ambiguus and blood pressure measurement, we examined the in vitro and in vivo effects of GPER activation in nucleus ambiguus neurons. A GPER selective agonist, G-1, produced a sustained increase in cytosolic Ca(2+) concentration in a concentration-dependent manner in retrogradely labelled cardiac vagal neurons of nucleus ambiguus. The increase in cytosolic Ca(2+) produced by G-1 was abolished by pretreatment with G36, a GPER antagonist. G-1 depolarized cultured cardiac vagal neurons of the nucleus ambiguus. The excitatory effect of G-1 was also identified by whole-cell visual patch-clamp recordings in nucleus ambiguus neurons, in medullary slices. To validate the physiological relevance of our in vitro studies, we carried out in vivo experiments. Microinjection of G-1 into the nucleus ambiguus elicited a decrease in heart rate; the effect was blocked by prior microinjection of G36. Systemic injection of G-1, in addition to a previously reported decrease in blood pressure, also reduced the heart rate. The G-1-induced bradycardia was prevented by systemic injection of atropine, a muscarinic antagonist, or by bilateral microinjection of G36 into the nucleus ambiguus. Our results indicate that GPER-mediated bradycardia occurs via activation of cardiac parasympathetic neurons of the nucleus ambiguus and support the involvement of the GPER in the modulation of cardiac vagal tone.
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Affiliation(s)
- G Cristina Brailoiu
- Neurological Surgery, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, USA
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Deliu E, Brailoiu GC, Mallilankaraman K, Wang H, Madesh M, Undieh AS, Koch WJ, Brailoiu E. Intracellular endothelin type B receptor-driven Ca2+ signal elicits nitric oxide production in endothelial cells. J Biol Chem 2012; 287:41023-31. [PMID: 23086942 DOI: 10.1074/jbc.m112.418533] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endothelin-1 exerts its actions via activation of ET(A) and ET(B) G(q/11) protein-coupled receptors, located in the plasmalemma, cytoplasm, and nucleus. Although the autocrine/paracrine nature of endothelin-1 signaling has been extensively studied, its intracrine role has been largely attributed to interaction with receptors located on nuclear membranes and the nucleoplasm. Because ET(B) receptors have been shown to be targeted to endolysosomes, we used intracellular microinjection and concurrent imaging methods to test their involvement in Ca(2+) signaling and subsequential NO production. We provide evidence that microinjected endothelin-1 produces a dose-dependent elevation in cytosolic calcium concentration in ET(B)-transfected cells and endothelial cells; this response is sensitive to ET(B) but not ET(A) receptor blockade. In endothelial cells, the endothelin-1-induced Ca(2+) response is abolished upon endolysosomal but not Golgi disruption. Moreover, the effect is prevented by inhibition of microautophagy and is sensitive to inhibitors of the phospholipase C and inositol 1,4,5-trisphosphate receptor. Furthermore, intracellular endothelin-1 increases nitric oxide via an ET(B)-dependent mechanism. Our results indicate for the first time that intracellular endothelin-1 activates endolysosomal ET(B) receptors and increase cytosolic Ca(2+) and nitric oxide production. Endothelin-1 acts in an intracrine fashion on endolysosomal ET(B) to induce nitric oxide formation, thus modulating endothelial function.
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Affiliation(s)
- Elena Deliu
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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Chitravanshi VC, Kawabe K, Sapru HN. Bradycardic effects of microinjections of urocortin 3 into the nucleus ambiguus of the rat. Am J Physiol Regul Integr Comp Physiol 2012; 303:R1023-30. [PMID: 23019211 DOI: 10.1152/ajpregu.00224.2012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The presence of urocortin 3 (UCN3) and CRF2 receptors (CRF2R) has been demonstrated in brain tissue. Nucleus ambiguus (nAmb) is the predominant brain area providing parasympathetic innervation to the heart. On the basis of these reports, it was hypothesized that activation of CRF2Rs in the nAmb may elicit cardiac effects. Experiments were carried out in urethane-anesthetized, artificially ventilated, and adult male Wistar rats. Microinjections of l-glutamate (l-GLU, 5 mM) were used to identify the nAmb. Different concentrations of UCN3 (0.031, 0.062, 0.125, 0.25, and 0.5 mM) microinjected into the nAmb elicited decreases in heart rate (HR) (5.3 ± 1, 22 ± 3.3, 38 ± 4.9, 45.7 ± 2.7, and 27.3 ± 2.3 bpm, respectively). The volume of all microinjections was 30 nl. Blood pressure changes concomitant with decreases in HR were not observed. Bradycardia elicited by microinjections of UCN3 (0.25 mM; maximally effective concentration) into the nAmb was significantly (P < 0.05) attenuated by microinjections of selective CRF2R antagonists (K41498, 0.5 mM, and astressin 2B, 0.25 mM) at the same site. Bilateral vagotomy abolished the bradycardic responses to UCN3. These results indicated that activation of CRF2Rs in the nAmb by UCN3 elicited bradycardia, which was vagally mediated. UCNs have been reported to exert cardioprotective effects in heart failure and ischemia/reperfusion injury. In this situation, centrally induced bradycardia by UCN3 would be beneficial. The results of the present investigation provide a platform for future studies on the role of CRF2Rs in the nAmb in pathological states such as heart failure.
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Affiliation(s)
- Vineet C Chitravanshi
- Dept. of Neurological Surgery, UMDNJ-New Jersey Medical School, Newark, NJ 07103, USA
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