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Barretto-de-Souza L, Benini R, Reis-Silva LL, Busnardo C, Crestani CC. Role of corticotropin-releasing factor neurotransmission in the lateral hypothalamus on baroreflex impairment evoked by chronic variable stress in rats. Pflugers Arch 2024; 476:351-364. [PMID: 38228895 DOI: 10.1007/s00424-024-02904-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/23/2023] [Accepted: 01/02/2024] [Indexed: 01/18/2024]
Abstract
Despite the importance of physiological responses to stress in a short-term, chronically these adjustments may be harmful and lead to diseases, including cardiovascular diseases. The lateral hypothalamus (LH) has been reported to be involved in expression of physiological and behavioral responses to stress, but the local neurochemical mechanisms involved are not completely described. The corticotropin-releasing factor (CRF) neurotransmission is a prominent brain neurochemical system implicated in the physiological and behavioral changes induced by aversive threats. Furthermore, chronic exposure to aversive situations affects the CRF neurotransmission in brain regions involved in stress responses. Therefore, in this study, we evaluated the influence of CRF neurotransmission in the LH on changes in cardiovascular function and baroreflex activity induced by chronic variable stress (CVS). We identified that CVS enhanced baseline arterial pressure and impaired baroreflex function, which were followed by increased expression of CRF2, but not CRF1, receptor expression within the LH. Local microinjection of either CRF1 or CRF2 receptor antagonist within the LH inhibited the baroreflex impairment caused by CVS, but without affecting the mild hypertension. Taken together, the findings documented in this study suggest that LH CRF neurotransmission participates in the baroreflex impairment related to chronic stress exposure.
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Affiliation(s)
- Lucas Barretto-de-Souza
- Laboratory of Pharmacology, Department of Drugs and Medicines, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jau Km 01, Araraquara, São Paulo, 14800-903, Brazil
| | - Ricardo Benini
- Laboratory of Pharmacology, Department of Drugs and Medicines, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jau Km 01, Araraquara, São Paulo, 14800-903, Brazil
| | - Lilian L Reis-Silva
- Laboratory of Pharmacology, Department of Drugs and Medicines, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jau Km 01, Araraquara, São Paulo, 14800-903, Brazil
| | - Cristiane Busnardo
- Laboratory of Pharmacology, Department of Drugs and Medicines, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jau Km 01, Araraquara, São Paulo, 14800-903, Brazil
| | - Carlos C Crestani
- Laboratory of Pharmacology, Department of Drugs and Medicines, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jau Km 01, Araraquara, São Paulo, 14800-903, Brazil.
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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: 1.8] [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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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: 2.3] [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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Corticotropin releasing factor excites neurons of posterior hypothalamic nucleus to produce tachycardia in rats. Sci Rep 2016; 6:20206. [PMID: 26831220 PMCID: PMC4735335 DOI: 10.1038/srep20206] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/23/2015] [Indexed: 12/26/2022] Open
Abstract
Corticotropin releasing factor (CRF), a peptide hormone involved in the stress response, holds a key position in cardiovascular regulation. Here, we report that the central effect of CRF on cardiovascular activities is mediated by the posterior hypothalamic nucleus (PH), an important structure responsible for stress-induced cardiovascular changes. Our present results demonstrate that CRF directly excites PH neurons via two CRF receptors, CRFR1 and CRFR2, and consequently increases heart rate (HR) rather than the mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). Bilateral vagotomy does not influence the tachycardia response to microinjection of CRF into the PH, while β adrenergic receptor antagonist propranolol almost totally abolishes the tachycardia. Furthermore, microinjecting CRF into the PH primarily increases neuronal activity of the rostral ventrolateral medulla (RVLM) and rostral ventromedial medulla (RVMM), but does not influence that of the dorsal motor nucleus of the vagus nerve (DMNV). These findings suggest that the PH is a critical target for central CRF system in regulation of cardiac activity and the PH-RVLM/RVMM-cardiac sympathetic nerve pathways, rather than PH-DMNV-vagus pathway, may contribute to the CRF-induced tachycardia.
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Ciriello J. Sex and estrogen affect the distribution of urocortin-1 immunoreactivity in brainstem autonomic nuclei of the rat. Brain Res Bull 2015; 116:81-92. [PMID: 26146233 DOI: 10.1016/j.brainresbull.2015.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 06/27/2015] [Accepted: 06/29/2015] [Indexed: 12/30/2022]
Abstract
Urocortin-1 (UCN-1), a neuropeptide closely related to the hypothalamic hormone corticotropin-releasing factor, has been associated with stress, feeding behaviors, cardiovascular control, and to exhibit functional gender differences. This study was done to investigate whether estrogen (E; 17β-estradiol) treatment (9 weeks) altered UCN-1 immunoreactivity in brainstem autonomic nuclei in female Wistar rats. Experiments were done in age matched adult males (controls), females (intact), and ovariectomized (OVX) only and OVX+E (30pg/ml plasma) treated females. All animals received intracerebroventricular injections of colchicine and were then perfused transcardially with Zamboni's fixative. Coronal brainstem sections (40μm) were cut and processed immunohistochemically for UCN-1. In males, moderate UCN-1 fiber labeling was found in the nucleus of the solitary tract (NTS) and throughout the rostral ventral lateral medulla (RVLM). Additionally, a few UCN-1 immunoreactive neurons were observed in hypoglossal nucleus (XII), facial nucleus (FN) and nucleus ambiguus (Amb). In intact females and OVX+E females, fewer UCN-1 labeled fibers were found within NTS compared to males. In contrast, the RVLM was more densely innervated in the female cases. Furthermore, in both intact and OVX+E females UCN-1 labeled neurons were found not only within Amb, FN and XII, but also within NTS, RVLM and nucleus raphé pallidus (RP). In OVX only animals, moderate to dense UCN-1 fiber labeling was observed in the NTS complex and throughout RVLM compared to males and the other female groups. However, in contrast to all other groups, UCN-1 labeled neurons were found in greater number within Amb, FN, NTS, dorsal motor nucleus of the vagus, XII, RVLM, magnocellular reticular nucleus and RP. These data not only suggest that sex differences exist in the distribution of UCN-1 within brainstem autonomic areas, but that circulating level of E may play an important role with regards to the function of these UCN-1 neurons during stress responses.
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Affiliation(s)
- John Ciriello
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON N6A5C1, Canada.
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Chitravanshi VC, Kawabe K, Sapru HN. GABA and glycine receptors in the nucleus ambiguus mediate tachycardia elicited by chemical stimulation of the hypothalamic arcuate nucleus. Am J Physiol Heart Circ Physiol 2015; 309:H174-84. [PMID: 25957221 DOI: 10.1152/ajpheart.00801.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 05/01/2015] [Indexed: 02/07/2023]
Abstract
We have previously reported that stimulation of the hypothalamic arcuate nucleus (ARCN) by microinjections of N-methyl-d-aspartic acid (NMDA) elicits tachycardia, which is partially mediated via inhibition of vagal inputs to the heart. The neuronal pools and neurotransmitters in them mediating tachycardia elicited from the ARCN have not been identified. We tested the hypothesis that the tachycardia elicited from the ARCN may be mediated by inhibitory neurotransmitters in the nucleus ambiguus (nAmb). Experiments were done in urethane-anesthetized, artificially ventilated, male Wistar rats. In separate groups of rats, unilateral and bilateral microinjections of muscimol (1 mM), gabazine (0.01 mM), and strychnine (0.5 mM) into the nAmb significantly attenuated tachycardia elicited by unilateral microinjections of NMDA (10 mM) into the ARCN. Histological examination of the brains showed that the microinjections sites were within the targeted nuclei. Retrograde anatomic tracing from the nAmb revealed direct bilateral projections from the ARCN and hypothalamic paraventricular nucleus to the nAmb. The results of the present study suggest that tachycardia elicited by stimulation of the ARCN by microinjections of NMDA is mediated via GABAA and glycine receptors located in the nAmb.
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Affiliation(s)
- Vineet C Chitravanshi
- Department of Neurological Surgery, Rutgers New Jersey Medical School, Newark, New Jersey
| | - Kazumi Kawabe
- Department of Neurological Surgery, Rutgers New Jersey Medical School, Newark, New Jersey
| | - Hreday N Sapru
- Department of Neurological Surgery, Rutgers New Jersey Medical School, Newark, New Jersey
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Liu C, Liu X, Yang J, Duan Y, Yao H, Li F, Zhang X. The effects of vasoactive peptide urocortin 2 on hemodynamics in spontaneous hypertensive rat and the role of L-type calcium channel and CRFR2. Pharmacol Rep 2015; 67:394-8. [DOI: 10.1016/j.pharep.2014.10.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 08/27/2014] [Indexed: 01/28/2023]
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Brailoiu GC, Deliu E, Altmann JB, Chitravanshi V, Brailoiu E. Evidence for role of acid-sensing ion channels in nucleus ambiguus neurons: essential differences in anesthetized versus awake rats. J Comp Physiol B 2014; 184:753-61. [PMID: 24752669 DOI: 10.1007/s00360-014-0829-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 03/24/2014] [Accepted: 04/01/2014] [Indexed: 11/29/2022]
Abstract
Acid-sensing ion channels (ASIC) are widely expressed in several brain regions including medulla; their role in physiology and pathophysiology is incompletely understood. We examined the effect of acidic pH of 6.2 on the medullary neurons involved in parasympathetic cardiac control. Our results indicate that retrogradely labeled cardiac vagal neurons of nucleus ambiguus are depolarized by acidic pH. In addition, acidic saline of pH 6.2 increases cytosolic Ca(2+) concentration by promoting Ca(2+) influx in nucleus ambiguus neurons. In vivo studies indicate that microinjection of acidic artificial cerebrospinal fluid (pH 6.2) into the nucleus ambiguus decreases the heart rate in conscious rats, whereas it has no effect in anesthetized animals. Pretreatment with either amiloride or benzamil, two widely used ASIC blockers, abolishes both the in vitro and in vivo effects elicited by pH 6.2. Our findings support a critical role for ASIC in modulation of cardiac vagal tone and provide a potential mechanism for acidosis-induced bradycardia, while identifying important differences in the response to acidic pH between anesthetized and conscious rats.
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Affiliation(s)
- G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Thomas Jefferson University, Jefferson School of Pharmacy, Philadelphia, PA, 19107, 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: 1.0] [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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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: 1.1] [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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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 PMCID: PMC3779113 DOI: 10.1113/jphysiol.2013.257204] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 07/19/2013] [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: 2.7] [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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13
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Chitravanshi VC, Kawabe K, Sapru HN. Mechanisms of cardiovascular actions of urocortins in the hypothalamic arcuate nucleus of the rat. Am J Physiol Heart Circ Physiol 2013; 305:H182-91. [PMID: 23686711 DOI: 10.1152/ajpheart.00138.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The presence of urocortins (UCNs) and corticotropin-releasing factor (CRF) receptors has been reported in the hypothalamic arcuate nucleus (ARCN). We have previously reported that UCNs are involved in central cardiovascular regulation. Based on this information, we hypothesized that the ARCN may be one of the sites where UCNs exert their central cardiovascular actions. Experiments were done in artificially ventilated, adult male Wistar rats anesthetized with urethane. Unilateral microinjections (30 nl) of UCN1 (0.12-2 mM) elicited decreases in mean arterial pressure (MAP) and heart rate (HR). Maximum cardiovascular responses were elicited by a 1 mM concentration of UCN1. Microinjections of UCN2 and UCN3 (1 mM each) into the ARCN elicited similar decreases in MAP and HR. UCN1 was used as a prototype for the other experiments described below. HR responses elicited by UCN1 were significantly attenuated by bilateral vagotomy. Prior microinjections of NBI-27914 (CRF-1 receptor antagonist) and astressin (CRF-1 receptor and CRF-2 receptor antagonist) (1 mM each) into the ARCN significantly attenuated the cardiovascular responses elicited by UCN1 microinjections at the same site. Microinjections of UCN1 into the ARCN decreased efferent renal sympathetic nerve activity. It was concluded that microinjections of UCN1, UCN2, and UCN3 into the ARCN elicited decreases in MAP and HR. Decreases in MAP, HR, and renal sympathetic nerve activity elicited by UCN1 microinjections into the ARCN were mediated via CRF receptors. Bradycardic responses to UCN1 were mediated via the activation of vagus nerves, and decreases in MAP may be mediated via decreases in sympathetic nerve activity.
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Affiliation(s)
- Vineet C Chitravanshi
- Department of Neurological Surgery, New Jersey Medical School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA
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