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Mousa SA, Dehe L, Aboryag N, Shaqura M, Beyer A, Schäfer M, Treskatsch S. Identification of glucocorticoid receptors as potential modulators of parasympathetic and sympathetic neurons within rat intracardiac ganglia. Front Neuroanat 2022; 16:902738. [PMID: 36213610 PMCID: PMC9539283 DOI: 10.3389/fnana.2022.902738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 09/07/2022] [Indexed: 11/30/2022] Open
Abstract
Background Emerging evidences indicate that glucocorticoid receptors (GR) play a regulatory role in cardiac function, particularly with regard to the autonomic nervous system. Therefore, this study aimed to demonstrate the expression and the precise anatomical location of GR in relation to the parasympathetic and sympathetic innervations of the heart. Methods The present study used tissue samples from rat heart atria to perform conventional reverse-transcriptase polymerase chain reaction (RT-PCR), Western blot, and double immunofluorescence confocal analysis of GR with the neuronal markers vesicular acetylcholine transporter (VAChT), tyrosine hydroxylase (TH), calcitonin gene-related peptide (CGRP) as well as the mineralocorticoid receptor (MR). Results Double immunofluorescence labeling revealed that GRs were co-expressed with VAChT in parasympathetic principal neuronal somata and nerve terminals innervating atrium. Also, GR colocalized with the sympathetic neuronal marker TH in a cluster of small intensely fluorescent (SIF) cells, on intracardiac nerve terminals and in the atrial myocardium. GR immunoreactivity was scarcely identified on CGRP-immunoreactive sensory nerve terminals. Approximately 20% of GR immunoreactive neuronal somata co-localized with MR. Finally, conventional RT-PCR and Western blot confirmed the presence of GR and MR in rat heart atria. Conclusion This study provides evidence for the existence of GR predominantly on cardiac parasympathetic neurons and TH-immunoreactive SIF cells suggesting a functional role of cardiac GR on cardiovascular function by modulation of the cardiac autonomic nervous system.
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Affiliation(s)
- Shaaban A. Mousa
- Department of Anaesthesiology and Intensive Care Medicine, Charité – University Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Campus Benjamin Franklin, Berlin, Germany
| | - Lukas Dehe
- Department of Anaesthesiology and Intensive Care Medicine, Charité – University Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Campus Benjamin Franklin, Berlin, Germany
| | - Noureddin Aboryag
- Department of Anaesthesiology and Intensive Care Medicine, Charité – University Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Campus Benjamin Franklin, Berlin, Germany
| | - Mohammed Shaqura
- Department of Anaesthesiology and Intensive Care Medicine, Charité – University Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Campus Benjamin Franklin, Berlin, Germany
| | - Antje Beyer
- Department of Anaesthesiology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Michael Schäfer
- Department of Anaesthesiology and Intensive Care Medicine, Charité – University Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Campus Benjamin Franklin, Berlin, Germany
| | - Sascha Treskatsch
- Department of Anaesthesiology and Intensive Care Medicine, Charité – University Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Campus Benjamin Franklin, Berlin, Germany
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Tumanova TS, Кokurina TN, Rybakova GI, Aleksandrov VG. Dexamethasone attenuates the modulatory effect of the insular cortex on the baroreflex in anesthetized rat. Can J Physiol Pharmacol 2021; 100:334-340. [PMID: 34644509 DOI: 10.1139/cjpp-2021-0385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The arterial baroreflex (BR) is an important neural mechanism for the stabilization of arterial pressure (AP). It is known that the insular cortex (IC) and other parts of the central autonomic network (CAN) are able to modulate the BR arc, altering baroreflex sensitivity (BRS). In addition, the sensitivity of the BR changes under the influence of hormones, in particular glucocorticoids (GC). It has been suggested that GC may influence BRS by altering the ability of the IC to modulate the BR. This hypothesis has been tested in experiments on rats anesthetized with urethane. It was found that microelectrostimulation of the visceral area in the left IC causes a short-term drop in AP, which is accompanied by bradycardia, and impairs BRS. The synthetic GC dexamethasone (DEX) did not significantly affect the magnitude of depressor responses but increased BRS and impaired the effect of IC stimulation on the BR. The results obtained confirm the hypothesis put forward and suggest that GC can attenuate the inhibitory effects of the IC on the BR arc, thereby enhancing the sensitivity of the BR.
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Affiliation(s)
- Tatiana Sergeevna Tumanova
- Pavlov Institute of Physiology RAS, 68594, Sankt Peterburg, Russian Federation.,Herzen State Pedagogical University of Russia, 104720, Biology, Sankt-Peterburg, Russian Federation;
| | | | | | - Viacheslav G Aleksandrov
- Pavlov Institute of Physiology RAS, 68594, 6, nab. Makarova, Sankt Peterburg, Russian Federation, 199034;
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3
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Vodička M, Vavřínová A, Mikulecká A, Zicha J, Behuliak M. Hyper-reactivity of HPA axis in Fischer 344 rats is associated with impaired cardiovascular and behavioral adaptation to repeated restraint stress. Stress 2020; 23:667-677. [PMID: 32543321 DOI: 10.1080/10253890.2020.1777971] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Fischer 344 (F344) rats are characterized by the hyper-reactive hypothalamic-pituitary-adrenal axis to stressful stimuli, while Lewis (LEW) rats are considered to be hypo-reactive. We studied stress-induced cardiovascular, neuroendocrine, and behavioral responses of adult male F344 and LEW rats subjected to the single (120 min) or the repeated restraint stress (daily 120 min for 1 week). Mean arterial pressure (MAP) and heart rate (HR) were measured in the restrained rats (n = 7-8 for each group) via a catheter inserted into the femoral artery. Baroreceptor sensitivity was evaluated using NO donor sodium nitroprusside and α1-adrenoceptor agonist phenylephrine. The plasma levels of adrenocorticotropic hormone (ACTH), corticosterone, aldosterone, and adrenaline were determined before and during the restraint. Exploratory behavior was tested in open field test. F344 rats exerted the augmented stress-induced increase in plasma ACTH, corticosterone, and adrenaline as well as the impaired endocrine adaptation to the repeated stress compared to LEW rats. F344 rats exhibited higher MAP than LEW rats during single and repeated restraint. Moreover, repeatedly restrained F344 showed elevated HR and diminished baroreflex sensitivity. F344 and LEW rats exhibited similar total locomotor activity and the time spent in the center of open field arena, both parameters being decreased by the repeated restraint. The detailed analysis revealed altered pattern of locomotor behavior in F344 rats subjected to repeated restraint. In conclusion, F344 rats showed the impaired endocrine adaptation that resulted in allostatic overload, which might contribute to the impaired cardiovascular and behavioral adaptation to chronic stress observed in this strain. Lay summary F344 rats, characterized by HPA axis hyper-reactivity, exhibited higher blood pressure during restraint than LEW rats. Moreover, repeatedly restrained F344 rats showed elevated heart rate and impaired baroreflex sensitivity. It can be concluded that a poor adaptation to the repeated stress in F344 rats is not only limited to the neuroendocrine response but also has important cardiovascular consequences.
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Affiliation(s)
- Martin Vodička
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Anna Vavřínová
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Anna Mikulecká
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Josef Zicha
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Michal Behuliak
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
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4
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Schulz A, Richter S, Ferreira de Sá DS, Vögele C, Schächinger H. Cortisol rapidly increases baroreflex sensitivity of heart rate control, but does not affect cardiac modulation of startle. Physiol Behav 2020; 215:112792. [PMID: 31870942 DOI: 10.1016/j.physbeh.2019.112792] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 11/14/2019] [Accepted: 12/19/2019] [Indexed: 11/25/2022]
Abstract
Cortisol, the final product of human HPA axis activation, rapidly modulates the cortical processing of afferent signals originating from the cardiovascular system. While peripheral effects have been excluded, it remains unclear whether this effect is mediated by cortical or subcortical (e.g. brainstem) CNS mechanisms. Cardiac modulation of startle (CMS) has been proposed as a method to reflect cardio-afferent signals at subcortical (potentially brainstem-) level. Using a single blind, randomized controlled design, the cortisol group (n = 16 volunteers) received 1 mg cortisol intravenously, while the control group (n = 16) received a placebo substance. The CMS procedure involved the assessment of eye blink responses to acoustic startle stimuli elicited at six different latencies to ECG-recorded R-waves (R + 0, 100, 200, 300, 400 and 500 ms). CMS was assessed at four measurement points: baseline, -16 min, +0 min, and +16 min relative to substance application. Baroreflex sensitivity (BRS) of heart rate (HR) control was measured non-invasively based on spontaneous beat-to-beat HR and systolic blood pressure changes. In the cortisol group, salivary cortisol concentration increased after IV cortisol administration, indicating effective distribution of the substance throughout the body. Furthermore, BRS increased in the cortisol group after cortisol infusion. There was no effect of cortisol on the CMS effect, however. These results suggest that low doses of cortisol do not affect baro-afferent signals, but central or efferent components of the arterial baroreflex circuit presumably via rapid, non-genomic mechanisms.
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Affiliation(s)
- André Schulz
- Institute for Health and Behaviour, Department of Behavioural and Cognitive Sciences, Faculty of Humanities, Education and Social Sciences, University of Luxembourg, 11, Porte des Sciences, Esch-sur-Alzette L-4366, Luxembourg; Division of Clinical Psychophysiology, Institute of Psychobiology, University of Trier, Trier, Germany.
| | - Steffen Richter
- Division of Clinical Psychophysiology, Institute of Psychobiology, University of Trier, Trier, Germany; Competence Center of Sleep Medicine, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Diana S Ferreira de Sá
- Division of Clinical Psychophysiology, Institute of Psychobiology, University of Trier, Trier, Germany; Division of Clinical Psychology and Psychotherapy, Department of Psychology, Saarland University, Saarbrücken, Germany
| | - Claus Vögele
- Institute for Health and Behaviour, Department of Behavioural and Cognitive Sciences, Faculty of Humanities, Education and Social Sciences, University of Luxembourg, 11, Porte des Sciences, Esch-sur-Alzette L-4366, Luxembourg
| | - Hartmut Schächinger
- Division of Clinical Psychophysiology, Institute of Psychobiology, University of Trier, Trier, Germany
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Ventura Spagnolo E, Mondello C, Cardia L, Minutoli L, Puzzolo D, Asmundo A, Macaione V, Alibrandi A, Malta C, Baldino G, Micali A. Post-Mortem Immunohistochemical Evidence of β2-Adrenergic Receptor Expression in the Adrenal Gland. Int J Mol Sci 2019; 20:ijms20123065. [PMID: 31234562 PMCID: PMC6628614 DOI: 10.3390/ijms20123065] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 06/20/2019] [Indexed: 12/13/2022] Open
Abstract
The evidence from post-mortem biochemical studies conducted on cortisol and catecholamines suggest that analysis of the adrenal gland could provide useful information about its role in human pathophysiology and the stress response. Authors designed an immunohistochemical study on the expression of the adrenal β2-adrenergic receptor (β2-AR), a receptor with high-affinity for catecholamines, with the aim to show which zones it is expressed in and how its expression differs in relation to the cause of death. The immunohistochemical study was performed on adrenal glands obtained from 48 forensic autopsies of subjects that died as a result of different pathogenic mechanisms using a mouse monoclonal β2-AR antibody. The results show that immunoreactivity for β2-AR was observed in all adrenal zones. Furthermore, immunoreactivity for β2-AR has shown variation in the localization and intensity of different patterns in relation to the original cause of death. To the best of our knowledge, this is the first study that demonstrates β2-AR expression in the human cortex and provides suggestions on the possible involvement of β2-AR in human cortex hormonal stimulation. In conclusion, the authors provide a possible explanation for the observed differences in expression in relation to the cause of death.
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Affiliation(s)
- Elvira Ventura Spagnolo
- Legal Medicine Section, Department for Health Promotion and Mother-Child Care, University of Palermo, Via del Vespro, 129, 90127 Palermo, Italy.
| | - Cristina Mondello
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, via Consolare Valeria, 1, 98125 Messina, Italy.
| | - Luigi Cardia
- Department of Human Pathology of Adult and Childhood "Gaetano Barresi", University of Messina, Via Consolare Valeria, 98125 Gazzi, Italy.
| | - Letteria Minutoli
- Department of Clinical and Experimental Medicine, University of Messina, via Consolare Valeria, 1, 98125 Messina, Italy.
| | - Domenico Puzzolo
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, via Consolare Valeria, 1, 98125 Messina, Italy.
| | - Alessio Asmundo
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, via Consolare Valeria, 1, 98125 Messina, Italy.
| | - Vincenzo Macaione
- Department of Clinical and Experimental Medicine, University of Messina, via Consolare Valeria, 1, 98125 Messina, Italy.
| | - Angela Alibrandi
- Department of Economics, Unit of Statistical and Mathematical Sciences, University of Messina, Via dei Verdi 75, 98122 Messina, Italy.
| | - Consuelo Malta
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, via Consolare Valeria, 1, 98125 Messina, Italy.
| | - Gennaro Baldino
- Legal Medicine Section, Department for Health Promotion and Mother-Child Care, University of Palermo, Via del Vespro, 129, 90127 Palermo, Italy.
| | - Antonio Micali
- Department of Biomedical and Dental Sciences and Morphofunctional Imaging, University of Messina, via Consolare Valeria, 1, 98125 Messina, Italy.
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6
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Adlan AM, Veldhuijzen van Zanten JJCS, Lip GYH, Paton JFR, Kitas GD, Fisher JP. Acute hydrocortisone administration reduces cardiovagal baroreflex sensitivity and heart rate variability in young men. J Physiol 2018; 596:4847-4861. [PMID: 30129666 PMCID: PMC6187027 DOI: 10.1113/jp276644] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 08/14/2018] [Indexed: 12/15/2022] Open
Abstract
KEY POINTS A surge in cortisol during acute physiological and pathophysiological stress may precipitate ventricular arrhythmia and myocardial infarction. Reduced cardiovagal baroreflex sensitivity and heart rate variability are observed during acute stress and are associated with an increased risk of acute cardiac events. In the present study, healthy young men received either a single iv bolus of saline (placebo) or hydrocortisone, 1 week apart, in accordance with a randomized, placebo-controlled, cross-over study design. Hydrocortisone acutely increased heart rate and blood pressure and reduced cardiovagal baroreflex sensitivity and heart rate variability in young men. These findings suggest that, by reducing cardiovagal baroreflex sensitivity and heart rate variability, acute surges in cortisol facilitate a pro-arrhythmic milieu and provide an important mechanistic link between stress and acute cardiac events ABSTRACT: Surges in cortisol concentration during acute stress may increase cardiovascular risk. To better understand the interactions between cortisol and the autonomic nervous system, we determined the acute effects of hydrocortisone administration on cardiovagal baroreflex sensitivity (BRS), heart rate variability (HRV) and cardiovascular reactivity. In a randomized, placebo-controlled, single-blinded cross-over study, 10 healthy males received either a single iv bolus of saline (placebo) or 200 mg of hydrocortisone, 1 week apart. Heart rate (HR), blood pressure (BP) and limb blood flow were monitored 3 h later, at rest and during the sequential infusion of sodium nitroprusside and phenylephrine (modified Oxford Technique), a cold pressor test and a mental arithmetic stress task. HRV was assessed using the square root of the mean of the sum of the squares of differences between successive R-R intervals (rMSSD). Hydrocortisone markedly increased serum cortisol 3 h following infusion and also compared to placebo. In addition, hydrocortisone elevated resting HR (+7 ± 4 beats min-1 ; P < 0.001) and systolic BP (+5 ± 5 mmHg; P = 0.008); lowered cardiovagal BRS [geometric mean (95% confidence interval) 15.6 (11.1-22.1) ms/mmHg vs. 26.2 (17.4--39.5) ms/mmHg, P = 0.011] and HRV (rMSSD 59 ± 29 ms vs. 84 ± 38 ms, P = 0.004) and increased leg vasoconstrictor responses to cold pressor test (Δ leg vascular conductance -45 ± 20% vs. -23 ± 26%; P = 0.023). In young men, an acute cortisol surge is accompanied by increases in HR and BP, as well as reductions in cardiovagal BRS and HRV, potentially providing a pro-arrhythmic milieu that may precipitate ventricular arrhythmia or myocardial infarction and increase cardiovascular risk.
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Affiliation(s)
- Ahmed M Adlan
- College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | | | - Gregory Y H Lip
- University of Birmingham Institute of Cardiovascular Sciences, City Hospital, Birmingham, UK
| | - Julian F R Paton
- Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - George D Kitas
- Department of Rheumatology, Dudley Group NHS Foundation Trust, Russells Hall Hospital, Dudley, West Midlands, UK
| | - James P Fisher
- College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK.,Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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7
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Cottin F, Malcurat V, Zorgati H, Prieur F, Labsy Z, Do MC, Gagey O, Collomp K. Effect of oral glucocorticoid intake on autonomic cardiovascular control. SPRINGERPLUS 2015; 4:622. [PMID: 26543757 PMCID: PMC4627994 DOI: 10.1186/s40064-015-1378-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 09/25/2015] [Indexed: 11/10/2022]
Abstract
This study analyzed baroreflex sensitivity, heart rate and systolic blood pressure variabilities during an oral 1 week administration of prednisone. This study examined the hypothesis that prednisone might change both systolic blood pressure level and baroreflex sensitivity. Twelve physically active male subjects participated to a double-blind, randomized cross-over study consisting of two 1-week periods of treatment separated by a 4-week drug-free washout period: placebo (PLA) or prednisone (PRED). Trials were performed by each subject four times on the second (D2) and seventh (D7) day of each treatment period. ECG and blood pressure were continuously recorded to compute heart rate variability, systolic blood pressure variability and baroreflex sensitivity components with the smoothed pseudo Wigner Ville distribution and baroreflex analysis. Following D2 prednisone treatment, both HR (PLA: 60.8 ± 10.5 vs. PRED: 65.8 ± 9.1 beats min(-1), p = 0.008) and low frequency component of systolic blood pressure variability (D2: 3.09 ± 0.19 vs. D7: 2.34 ± 0.19, p < 0.041) increased whereas other components did not change. Over 7 days of treatment, LF-SBP amplitude increased (D2: 2.71 ± 0.89 vs. D7: 3.87 ± 0.6 mmHg, p = 0.037). A slight increase in both HR and LF-SBPV were observed suggesting a potential sympathetic cardiovascular stimulus. Although we found a significant effect of the 1-week prednisone treatment on heart rate and low frequency power of systolic blood pressure variability, we reported neither an increase in the systolic blood pressure level nor a decrease in the baroreflex sensitivity. Therefore, the fragility of our results cannot support a deleterious effect of 1-week administration of prednisone on the autonomic cardiovascular control which might be involved in cardiovascular diseases.
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Affiliation(s)
- F Cottin
- CIAMS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France ; CIAMS, Université d'Orléans, 45067 Orléans, France
| | - V Malcurat
- CIAMS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France ; CIAMS, Université d'Orléans, 45067 Orléans, France ; Ecole supérieure d'ostéopathie, ESO Paris SUPOSTEO, Champs sur Marne, France
| | - H Zorgati
- CIAMS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France ; CIAMS, Université d'Orléans, 45067 Orléans, France
| | - F Prieur
- CIAMS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France ; CIAMS, Université d'Orléans, 45067 Orléans, France
| | - Z Labsy
- CIAMS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France ; CIAMS, Université d'Orléans, 45067 Orléans, France
| | - M C Do
- CIAMS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France ; CIAMS, Université d'Orléans, 45067 Orléans, France
| | - O Gagey
- CIAMS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France ; CIAMS, Université d'Orléans, 45067 Orléans, France
| | - K Collomp
- CIAMS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex, France ; CIAMS, Université d'Orléans, 45067 Orléans, France ; Département des analyses, AFLD, Châtenay-Malabry, France
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8
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Erdos B, Backes I, McCowan ML, Hayward LF, Scheuer DA. Brain-derived neurotrophic factor modulates angiotensin signaling in the hypothalamus to increase blood pressure in rats. Am J Physiol Heart Circ Physiol 2015; 308:H612-22. [PMID: 25576628 DOI: 10.1152/ajpheart.00776.2014] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) expression increases in the paraventricular nucleus of the hypothalamus (PVN) in response to hypertensive stimuli including stress and hyperosmolarity. However, it is unclear whether BDNF in the PVN contributes to increases in blood pressure (BP). We tested the hypothesis that increased BDNF levels within the PVN would elevate baseline BP and heart rate (HR) and cardiovascular stress responses by altering central angiotensin signaling. BP was recorded using radiotelemetry in male Sprague-Dawley rats after bilateral PVN injections of adeno-associated viral vectors expressing green fluorescent protein (GFP) or myc epitope-tagged BDNF fusion protein. Cardiovascular responses to acute stress were evaluated 3 to 4 wk after injections. Additional GFP and BDNF-treated animals were equipped with osmotic pumps for intracerebroventricular infusion of saline or the angiotensin type-1 receptor (AT1R) inhibitor losartan (15 μg·0.5 μl(-1)·h(-1)). BDNF treatment significantly increased baseline BP (121 ± 3 mmHg vs. 99 ± 2 mmHg in GFP), HR (394 ± 9 beats/min vs. 314 ± 4 beats/min in GFP), and sympathetic tone indicated by HR- and BP-variability analysis and adrenomedullary tyrosine hydroxylase protein expression. In contrast, body weight and BP elevations to acute stressors decreased. BDNF upregulated AT1R mRNA by ∼80% and downregulated Mas receptor mRNA by ∼50% in the PVN, and losartan infusion partially inhibited weight loss and increases in BP and HR in BDNF-treated animals without any effect in GFP rats. Our results demonstrate that BDNF overexpression in the PVN results in sympathoexcitation, BP and HR elevations, and weight loss that are mediated, at least in part, by modulating angiotensin signaling in the PVN.
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Affiliation(s)
- Benedek Erdos
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida; Department of Pharmacology, University of Vermont College of Medicine, Burlington, Vermont; and
| | - Iara Backes
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida
| | - Michael L McCowan
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida
| | - Linda F Hayward
- Department of Physiological Sciences, University of Florida, Gainesville, Florida
| | - Deborah A Scheuer
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida
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9
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Ghosal S, Bundzikova-Osacka J, Dolgas CM, Myers B, Herman JP. Glucocorticoid receptors in the nucleus of the solitary tract (NTS) decrease endocrine and behavioral stress responses. Psychoneuroendocrinology 2014; 45:142-53. [PMID: 24845185 PMCID: PMC4076411 DOI: 10.1016/j.psyneuen.2014.03.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 03/26/2014] [Accepted: 03/28/2014] [Indexed: 10/25/2022]
Abstract
Stress activates the hypothalamo-pituitary-adrenal (HPA) axis, leading to adrenocortical secretion of glucocorticoids. The magnitude and duration of the HPA axis response is mediated in large part by the glucocorticoid receptor (GR). The nucleus of the solitary tract (NTS) abundantly expresses the GR and is a key brain region for processing autonomic and endocrine stress responses. This study tests the hypothesis that GR within the NTS plays an important role in inhibiting stress-induced endocrine and behavioral responses. Cohorts of rats received bilateral micropellet (30 μg) implantations of crystalline corticosterone, mifepristone (a GR antagonist) or cholesterol (control) directed into the region of the NTS, and were subsequently subjected to either acute psychogenic (restraint) stress or chronic variable stress (CVS). We found that NTS GR antagonism increased acute stress-induced corticosterone levels, whereas GR activation within the NTS attenuated this response. Following CVS, basal and 15 min post-restraint plasma corticosterone levels were increased by NTS GR antagonism, which was associated with an increase in Fos immunoreactivity within the PVN. Using the elevated plus maze (EPM) and forced swim test (FST), we assessed the effect of NTS GR inhibition on anxiety- and depression-like behaviors, respectively. GR inhibition within the NTS decreased open arm exploratory behavior in the EPM and increased immobility in the FST relative to controls. Together, the findings reveal a novel role of NTS GR signaling for inhibiting both endocrine and behavioral responses to stress.
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Affiliation(s)
- Sriparna Ghosal
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati Metabolic Diseases Institute, Cincinnati, OH 45237, United States.
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10
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Bechtold AG, Patel G, Hochhaus G, Scheuer DA. Chronic blockade of hindbrain glucocorticoid receptors reduces blood pressure responses to novel stress and attenuates adaptation to repeated stress. Am J Physiol Regul Integr Comp Physiol 2009; 296:R1445-54. [PMID: 19279295 PMCID: PMC2689825 DOI: 10.1152/ajpregu.00095.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exogenous glucocorticoids act within the hindbrain to enhance the arterial pressure response to acute novel stress. Here we tested the hypothesis that endogenous glucocorticoids act at hindbrain glucocorticoid receptors (GR) to augment cardiovascular responses to restraint stress in a model of stress hyperreactivity, the borderline hypertensive rat (BHR). A 3- to 4-mg pellet of the GR antagonist mifepristone (Mif) was implanted over the dorsal hindbrain (DHB) in Wistar-Kyoto (WKY) and BHRs. Control pellets consisted of either sham DHB or subcutaneous Mif pellets. Rats were either subjected to repeated restraint stress (chronic stress) or only handled (acute stress) for 3-4 wk, then all rats were stressed on the final day of the experiment. BHR showed limited adaptation of the arterial pressure response to restraint, and DHB Mif significantly (P = 0.05) attenuated the arterial pressure response to restraint in both acutely and chronically stressed BHR. In contrast, WKY exhibited a substantial adaptation of the pressure response to repeated restraint that was significantly reversed by DHB Mif. DHB Mif and chronic stress each significantly increased baseline plasma corticosterone concentration and adrenal weight and reduced the corticosterone response to stress in all rats. We conclude that endogenous corticosterone acts via hindbrain GR to enhance the arterial pressure response to stress in BHR, but to promote the adaptation of the arterial pressure response to stress in normotensive rats. Endogenous corticosterone also acts in the hindbrain to restrain corticosterone at rest but to maintain the corticosterone response to stress in both BHR and WKY rats.
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Affiliation(s)
- Andrea G Bechtold
- Department of Medical Pharmacology, School of Medicine, University of California Davis, Davis, California, USA
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Djordjevic J, Vuckovic T, Jasnic N, Cvijic G. Effect of various stressors on the blood ACTH and corticosterone concentration in normotensive Wistar and spontaneously hypertensive Wistar-Kyoto rats. Gen Comp Endocrinol 2007; 153:217-20. [PMID: 17383653 DOI: 10.1016/j.ygcen.2007.02.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Revised: 01/30/2007] [Accepted: 02/02/2007] [Indexed: 11/30/2022]
Abstract
The role of the sympathetic nervous system (SNS) and the hypothalamo-pituitary-adrenal (HPA) axis in the stress response is well documented. The imbalance in a central and peripheral SNS activity accompanied by the HPA hyperresponsivity has been observed in essential and experimental hypertension. The spontaneously hypertensive rats (SHR) are extensively used in studying mechanisms of the essential hypertension. The blood ACTH and corticosterone concentration was examined in spontaneously hypertensive (Wistar-Kyoto) and normotensive (Wistar) adult male rats exposed to acute cold (2h) or immobilization (2h) stress as well as chronic (21days) isolation stress or their combination. The present results show that SHR in basal conditions have higher blood ACTH and corticosterone level as compared to the normotensive rats. Both the acute exposure to cold and immobilization stress induced a higher increment in SHR plasma ACTH in respect to Wistar rats. The similar pattern of ACTH response occurred when SHR were previously chronically isolated and acutely exposed to both applied stressors. Surprisingly, corticosterone concentration did not differ between control rats with or without 21days isolation or those exposed to a cold or immobile acute stressor.
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Affiliation(s)
- Jelena Djordjevic
- Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Studentski Trg 16, P.O. Box 52, 11000 Belgrade, Serbia and Montenegro.
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Li F, Wood CE, Keller-Wood M. Adrenalectomy alters regulation of blood pressure and endothelial nitric oxide synthase in sheep: modulation by estradiol. Am J Physiol Regul Integr Comp Physiol 2007; 293:R257-66. [PMID: 17459913 DOI: 10.1152/ajpregu.00082.2007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hypoadrenocorticism produces more severe hypotension during the peripartal period in pregnant ewes and women. We hypothesized that estradiol increases the severity of hypotension after withdrawal of corticosteroids and that this results from combined effects of adrenalectomy and estradiol to increase endothelial nitric oxide synthase (eNOS). In study I, blood pressure and eNOS mRNA and protein in aorta, uterine, renal, and mesenteric arteries were measured in intact ewes or adrenalectomized ewes 18–20 h after cessation of infusion of cortisol and aldosterone; half of each group ewes were treated with estradiol. In study II, adrenalectomized ewes were similarly studied 22–28 h after withdrawal of corticosteroids. Estradiol treatment in both studies significantly increased eNOS mRNA and protein in uterine artery, whereas corticosteroid withdrawal decreased expression of eNOS mRNA and protein in uterine artery. In both studies, adrenalectomy and steroid withdrawal decreased mean arterial pressure. In study II, four of six adrenalectomized ewes not treated with estradiol showed dramatic phasic variations in blood pressure and heart rate with a period of ∼20 s, developing within 22–28 h after corticosteroid withdrawal. Although there was no effect of estradiol on blood pressure in study I, in study II, ewes treated with estradiol did not develop this pattern. Estradiol also slowed both the decline in plasma sodium and the rise in plasma potassium after corticosteroid withdrawal. These results disprove the hypothesis that estradiol increases the severity of hypotension during hypoadrenocorticism. However, the study reveals an important effect of corticosteroid withdrawal on blood pressure, consistent with corticosteroid modulation of baroreflex responsiveness.
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Affiliation(s)
- Feng Li
- Department of Pharmacodynamics, University of Florida, Gainesville, FL 32610-0487, USA
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Scheuer DA, Bechtold AG, Vernon KA. Chronic activation of dorsal hindbrain corticosteroid receptors augments the arterial pressure response to acute stress. Hypertension 2006; 49:127-33. [PMID: 17088452 PMCID: PMC5730874 DOI: 10.1161/01.hyp.0000250088.15021.c2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Augmented cardiovascular responses to acute stress can predict cardiovascular disease in humans. Chronic systemic increases in glucocorticoids produce enhanced cardiovascular responses to psychological stress; however, the site of action is unknown. Recent evidence indicates that glucocorticoids can act within the dorsal hindbrain to modulate cardiovascular function. Therefore, we tested the hypothesis that the endogenous glucocorticoid corticosterone can act in the dorsal hindbrain to enhance cardiovascular responses to restraint stress in conscious rats. Adrenal-intact animals with indwelling arterial catheters were treated for 4 or 6 days with 3- to 4-mg pellets of corticosterone or silastic (sham pellets) implanted on the dorsal hindbrain surface. Corticosterone pellets were also implanted either on the surface of the dura or subcutaneously to control for the systemic effects of corticosterone (systemic corticosterone). The integrated increase in arterial pressure during 1 hour of restraint stress was significantly (P<0.05) greater in dorsal hindbrain corticosterone (912+/-98 mm Hg per 60 minutes) relative to dorsal hindbrain sham (589+/-57 mm Hg per 60 minutes) or systemic corticosterone (592+/-122 mm Hg per 60 minutes) rats. The plasma glucose response after 10 minutes of stress was also significantly higher in dorsal hindbrain corticosterone-treated rats relative to both other groups. There were no significant between-group differences in the heart rate or corticosterone responses to stress. There were no differences in baseline values for any measured parameters. We conclude that corticosterone can act selectively in the dorsal hindbrain in rats with normal plasma corticosterone levels to augment the arterial pressure response to restraint stress.
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Affiliation(s)
- Deborah A Scheuer
- School of Medicine, University of Florida, Gainesville 32610-0274, USA.
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Daubert DL, Brooks VL. Nitric oxide impairs baroreflex gain during acute psychological stress. Am J Physiol Regul Integr Comp Physiol 2006; 292:R955-61. [PMID: 17038446 DOI: 10.1152/ajpregu.00192.2006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Psychological stress can suppress baroreflex function, but the mechanism has not been fully elucidated. Nitric oxide in the brain and in the adrenal cortex, as well as plasma glucocorticoids, increases during stress and has been shown to suppress reflex gain in unstressed animals. Therefore, the purpose of this study was to test the hypothesis that stress, caused by exposure to a novel environment, decreases baroreflex gain in rabbits through the actions of nitric oxide to increase corticosterone release. Baroreflex control of heart rate and plasma corticosterone levels was quantified before and after blockade of nitric oxide synthase (NOS) with N(omega)-nitro-L-arginine (L-NNA; 20 mg/kg iv) in conscious rabbits exposed to a novel environment and in the same rabbits once they had been conditioned to the environment. Stress significantly reduced baroreflex gain from -23.4 +/- 2 to -12.2 +/- 1.6 beats x min(-1) x mmHg(-1) (P < 0.05) and increased plasma corticosterone levels from 5.4 +/- 0.7 to 15.5 +/- 5.0 ng/ml (P < 0.05). NOS blockade increased gain in stressed animals (to -27.2 +/- 5.4 beats x min(-1) x mmHg(-1), P < 0.05) but did not alter gain in unstressed rabbits (-26.8 +/- 4.9 beats x min(-1) x mmHg(-1)) such that gain was equalized between the two states. NOS blockade increased plasma corticosterone levels in unstressed animals (to 14.3 +/- 2.1 ng/ml, P < 0.05) but failed to significantly alter levels in stressed rabbits (14.0 +/- 3.9 ng/ml). In conclusion, psychological stress may act via nitric oxide, independently of increases in corticosterone, to decrease baroreflex gain.
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Affiliation(s)
- Daisy L Daubert
- Department of Physiology and Pharmacology, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, USA
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Heindl S, Vahlkamp K, Weitz G, Fehm HL, Dodt C. Differential effects of hydrocortisone on sympathetic and hemodynamic responses to sympathoexcitatory manoeuvres in men. Steroids 2006; 71:206-13. [PMID: 16388832 DOI: 10.1016/j.steroids.2005.10.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Revised: 10/03/2005] [Accepted: 10/12/2005] [Indexed: 11/30/2022]
Abstract
Aim of the present study was to investigate the influence of hydrocortisone on muscle sympathetic nerve activity (MSNA) and hemodynamic parameters during different sympathoexcitatory manoeuvres in humans. The study focuses on the interaction of the hypothalamo-pituitary-adrenal system and the sympathetic nervous system. Hydrocortisone 100 mg or placebo was administered intravenously to eight young healthy subjects in a double-blind crossover design. After 6 h, blood pressure, heart rate and MSNA from the peroneal nerve were recorded at rest, during an arithmetic stress task, an apnea and a cold pressor test. Hydrocortisone treatment increased serum cortisol levels to the upper physiological range and suppressed basal levels of adrenocorticotropin. During mental stress, MSNA, heart rate and blood pressure levels were elevated independently of hydrocortisone pre-treatment. However, hydrocortisone induced a sustained increase in basal heart rate throughout the whole experiment. A stronger increase in diastolic blood pressure was observed during apnea and cold pressor test in the hydrocortisone experiments. MSNA or plasma catecholamines at rest or during the manoeuvres were not affected by hydrocortisone. The observed hydrocortisone effects may be due to an increased responsiveness of adrenergic receptors towards catecholamines or a central modulation of the baroreflex involving parasympathetic mechanisms. Further studies are needed to confirm that the increase in MSNA during mental stress does not depend on a concomitant activation of the hypothalamo-pituitary-adrenal system.
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Affiliation(s)
- Silke Heindl
- Department of Internal Medicine I, University of Luebeck, Ratzeburger Allee 160, 23538 Luebeck, Germany.
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Hoen S, Mazoit JX, Asehnoune K, Brailly-Tabard S, Benhamou D, Moine P, Edouard AR. Hydrocortisone increases the sensitivity to α1-adrenoceptor stimulation in humans following hemorrhagic shock*. Crit Care Med 2005; 33:2737-43. [PMID: 16352953 DOI: 10.1097/01.ccm.0000189743.55352.0e] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To assess the pressor response to phenylephrine infusion before and after hydrocortisone in severe trauma patients and to correlate this response with their adrenal reserve. DESIGN Prospective clinical study. SETTING Surgical intensive care unit in a university teaching hospital. PATIENTS Twenty-three young trauma patients (Injury Severity Score, 38 +/- 14) were studied at the end of the resuscitative period (27 +/- 15 hrs after trauma). INTERVENTIONS Total cortisol response to intravenous corticotropin bolus (250 microg) was obtained. Total cortisol response <9 microg/dL defined an impaired adrenal function and the patient was called a nonresponder. Twelve to 24 hrs following this stimulation, phenylephrine was infused in a stepwise manner to establish the phenylephrine-mean arterial pressure dose-response curve before and after intravenous hydrocortisone administration (50 mg). An Emax model was used to describe the curve; the influence of the group (responder/nonresponder), the sequence (before/after hydrocortisone), and three covariates (Injury Severity Score, shock, and interleukin-6) were thereafter tested. MEASUREMENTS AND MAIN RESULTS Forty-three percent of patients were nonresponders. Total cortisol response was not correlated with serum albumin concentration and was negatively correlated with the interleukin-6 concentration. A trend for a higher incidence of nonresponders (53% vs. 36%) and a lesser total cortisol response (7.9 +/- 5.1 vs. 12.5 +/- 5.1 microg/dL) was observed in the shock patients. A phenylephrine dose-response structure (E0, ED50, and Emax) was described without influence of the group and the sequence. However, hydrocortisone induced a 37% decrease in ED50 without change in Emax in the shock patients. CONCLUSION An acute administration of hydrocortisone increases the sensitivity to alpha1-adrenoceptor stimulation in fully resuscitated severe trauma patients following hemorrhagic shock. This effect is independent of the adrenal reserve of the patients and different from that previously reported in septic patients.
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Affiliation(s)
- Sophie Hoen
- Service d'Anesthésie-Réanimation et Unité Propre de Recherche de l'Enseignement Supérieur-Equipe d'Accueil (UPRES-EA 3540), Hôpital de Bicêtre, Bicêtre, France
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Bechtold AG, Scheuer DA. Glucocorticoids act in the dorsal hindbrain to modulate baroreflex control of heart rate. Am J Physiol Regul Integr Comp Physiol 2005; 290:R1003-11. [PMID: 16269575 PMCID: PMC5730876 DOI: 10.1152/ajpregu.00345.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Systemic corticosterone (Cort) modulates arterial baroreflex control of both heart rate and renal sympathetic nerve activity. Because baroreceptor afferents terminate in the dorsal hindbrain (DHB), an area with dense corticosteroid receptor expression, we tested the hypothesis that prolonged activation of DHB Cort receptors increases the midpoint and reduces the gain of arterial baroreflex control of heart rate in conscious rats. Small (3-4 mg) pellets of Cort (DHB Cort) or Silastic (DHB Sham) were placed on the surface of the DHB, or Cort was administered systemically by placing a Cort pellet on the surface of the dura (Dura Cort). Baroreflex control of heart rate was determined in conscious male Sprague Dawley rats on each of 4 days after initiation of treatment. Plots of arterial pressure vs. heart rate were analyzed using a four-parameter logistic function. After 3 days of treatment, the arterial pressure midpoint for baroreflex control of heart rate was increased in DHB Cort rats (123 +/- 2 mmHg) relative to both DHB Sham (108 +/- 3 mmHg) and Dura Cort rats (109 +/- 2 mmHg, P < 0.05). On day 4, baseline arterial pressure was greater in DHB Cort (112 +/- 2 mmHg) compared with DHB Sham (105 +/- 2 mmHg) and Dura Cort animals (106 +/- 2 mmHg, P < 0.05), and the arterial pressure midpoint was significantly greater than mean arterial pressure in the DHB Cort group only. Also on day 4, maximum baroreflex gain was reduced in DHB Cort (2.72 +/- 0.12 beats x min(-1) x mmHg(-1)) relative to DHB Sham and Dura Cort rats (3.51 +/- 0.28 and 3.37 +/- 0.27 beats x min(-1) x mmHg(-1), P < 0.05). We conclude that Cort acts in the DHB to increase the midpoint and reduce the gain of the heart rate baroreflex function.
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Affiliation(s)
- Andrea G Bechtold
- Division of Pharmacology, University of Missouri-Kansas City, Kansas City, Missouri 64108, USA
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Broadley AJM, Korszun A, Abdelaal E, Moskvina V, Jones CJH, Nash GB, Ray C, Deanfield J, Frenneaux MP. Inhibition of Cortisol Production With Metyrapone Prevents Mental Stress-Induced Endothelial Dysfunction and Baroreflex Impairment. J Am Coll Cardiol 2005; 46:344-50. [PMID: 16022966 DOI: 10.1016/j.jacc.2005.03.068] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Revised: 03/21/2005] [Accepted: 03/29/2005] [Indexed: 11/23/2022]
Abstract
OBJECTIVES This study was designed to investigate the role of cortisol in stress-induced endothelial dysfunction and impaired baroreflex sensitivity (BRS) by blocking cortisol production with metyrapone before subjecting healthy volunteers to mental stress. BACKGROUND Mental stress raises cortisol levels and is associated with increased coronary heart disease (CHD) morbidity and mortality, especially from sudden cardiac death. It also causes endothelial dysfunction and impaired BRS. METHODS We measured brachial artery flow-mediated dilation (FMD), a measure of endothelial function, and BRS in 36 subjects without CHD risk factors who were then randomized in a double-blind fashion to oral metyrapone 750 mg x 2 or placebo. Five hours later we subjected subjects to mental stress and then remeasured endothelial function and BRS. RESULTS Prestress cortisol levels were significantly higher in the placebo group at 270.5 (30.9) nmol/l versus 89.1 (11.8) nmol/l (p = 0.01), and the increase with stress was higher at 57.9 (17.9) nmol/l versus 11.2 (2.2) nmol/l (p < 0.001). In the placebo group, compared to baseline, FMD and BRS fell significantly from 4.5% (0.7%) to 1.4% (1.1%) (p = 0.02) and 21.4 (2.3) ms/mmHg to 16.3 (1.5) ms/mmHg (p = 0.04), respectively. In the metyrapone group, FMD and BRS were unchanged from baseline: 4.3% (0.9%) versus 5.1% (0.8%) (p = 0.48) and 26.4 (2.9) ms/mmHg versus 24.9 (2.6) ms/mmHg (p = 0.62), respectively. Analysis of covariation showed a significant effect of metyrapone on change in both FMD (p = 0.009) and BRS (p = 0.024). CONCLUSIONS Stress-related endothelial dysfunction and BRS impairment can be prevented by blocking cortisol production with metyrapone, demonstrating a direct or facilitative role for cortisol in these phenomena and suggesting mechanisms by which stress contributes to CHD and sudden cardiac death.
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Scheuer DA, Bechtold AG, Shank SS, Akana SF. Glucocorticoids act in the dorsal hindbrain to increase arterial pressure. Am J Physiol Heart Circ Physiol 2004; 286:H458-67. [PMID: 14512285 DOI: 10.1152/ajpheart.00824.2003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucocorticoid receptors (GRs) are present at a high density in the nucleus of the solitary tract (NTS), an area of the dorsal hindbrain (DHB) that is critical for blood pressure regulation. However, whether these receptors play any role in the regulation of blood pressure is unknown. We tested the hypothesis that glucocorticoids act in the DHB to increase arterial pressure using two experimental strategies. In one approach, we implanted pellets of corticosterone (Cort) or sham pellets onto the DHB over the NTS. Compared with rats with sham pellets, rats with DHB Cort pellets had an increased ( P < 0.05) mean arterial pressure (111 ± 2 vs. 104 ± 1 mmHg) and heart rate (355 ± 9 vs. 326 ± 5 beats/min) after 4 days. In the second approach, we implanted subcutaneous Cort pellets to increase the systemic Cort concentration and then subsequently implanted pellets of the GR antagonist mifepristone (Mif; previously RU-38486) or sham pellets onto the DHB. Two days of DHB Mif treatment reduced ( P < 0.05) mean arterial pressure in those rats with elevated plasma Cort levels (118 ± 2 vs. 108 ± 1 mmHg for sham vs. Mif DHB pellets). Cort and Mif pellets placed on the dura had no effects on arterial pressure or heart rate, ruling out systemic cardiovascular effects of the steroids. DHB Cort treatment had no effects on plasma Cort concentration or adrenal weight, indicating that the contents of the DHB Cort pellet did not diffuse into the systemic circulation or into the forebrain areas that regulate plasma Cort concentration in concentrations sufficient to produce physiological effects. Immunohistochemistry for the occupied GRs demonstrated that the Cort and Mif from the DHB pellets were delivered to the DHB with minimal diffusion to the ventral hindbrain or forebrain. We conclude that glucocorticoids act in the DHB to increase arterial pressure.
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Affiliation(s)
- Deborah A Scheuer
- Dept. of Pharmacology, Univ. of Missouri-Kansas City, 2411 Holmes St., Rm. MG 111, Kansas City, MO 64108, USA.
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Affiliation(s)
- Harald M Stauss
- Dept. of Exercise Science, The Univ. of Iowa, Iowa City, IA 52242, USA.
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Shank SS, Scheuer DA. Glucocorticoids reduce responses to AMPA receptor activation and blockade in nucleus tractus solitarius. Am J Physiol Heart Circ Physiol 2003; 284:H1751-61. [PMID: 12531728 DOI: 10.1152/ajpheart.01033.2002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested the hypothesis that glucocorticoids attenuate changes in arterial pressure and renal sympathetic nerve activity (RSNA) in response to activation and blockade of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors within the nucleus of the solitary tract (NTS). Experiments were performed in Inactin-anesthetized male Sprague-Dawley rats treated for 7 +/- 1 days with a subcutaneous corticosterone (Cort) pellet or in control rats. Baseline mean arterial pressure (MAP) was significantly higher in Cort-treated rats (109 +/- 2 mmHg, n = 39) than in control rats (101 +/- 1 mmHg, n = 48, P < 0.05). In control rats, microinjection of AMPA (0.03, 0.1, and 0.3 pmol/100 nl) into the NTS significantly decreased MAP at all doses and decreased RSNA at 0.1 and 0.3 pmol/100 nl. Responses to AMPA in Cort-treated rats were attenuated at all doses of AMPA (P < 0.05). Responses to the AMPA-kainate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) were also significantly reduced in Cort-treated rats relative to control rats. Blockade of glucocorticoid type II receptors with mifepristone significantly enhanced responses to CNQX in both control and Cort rats. We conclude that glucocorticoids attenuate MAP and RSNA responses to activation and blockade of AMPA receptors in the NTS.
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Affiliation(s)
- Sylvan S Shank
- Department of Pharmacology, The University of Missouri, 2411 Holmes Street, Kansas City, MO 64108, USA
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Segar JL, Van Natta T, Smith OJ. Effects of fetal ovine adrenalectomy on sympathetic and baroreflex responses at birth. Am J Physiol Regul Integr Comp Physiol 2002; 283:R460-7. [PMID: 12121859 DOI: 10.1152/ajpregu.00056.2002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Studies were performed to test the hypothesis that the absence of adrenal glucocorticoids late in gestation alters sympathetic and baroreflex responses before and immediately after birth. Fetal sheep at 130-131 days gestation (term 145 days) were subjected to bilateral adrenalectomy before the normal prepartum increase in plasma cortisol levels. One group of fetuses (n = 5) received physiological cortisol replacement with a continuous infusion of hydrocortisone (2 mg x day(-1) x kg(-1) for 10 days), whereas the other group received 0.9% NaCl vehicle (n = 5). All animals underwent a second surgery 48 h before the study for placement of a renal nerve recording electrode. Heart rate (HR), mean arterial blood pressure (MABP), renal sympathetic nerve activity (RSNA), and baroreflex control of HR and RSNA were studied before and after cesarean section delivery. At the time of study (140-141 days gestation), fetal plasma cortisol concentration was undetectable in adrenalectomized (ADX) fetuses and 58 +/- 9 ng/ml in animals receiving cortisol replacement (ADX + F). Fetal and newborn MABP was significantly greater in ADX + F relative to ADX animals. One hour after delivery, MABP increased 13 +/- 3 mmHg and RSNA increased 91 +/- 12% above fetal values in ADX + F (both P < 0.05) but remained unchanged in ADX lambs. The midpoint pressures of the fetal HR and RSNA baroreflex function curves were significantly greater in ADX + F (54 +/- 3 and 56 +/- 3 mmHg for HR and RSNA curves, respectively) than ADX fetuses (45 +/- 2 and 46 +/- 3 mmHg). After delivery, the baroreflex curves reset toward higher pressure in ADX + F but not ADX lambs. These results suggest that adrenal glucocorticoids contribute to cardiovascular regulation in the late-gestation fetus and newborn by modulating arterial baroreflex function and sympathetic activity.
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Affiliation(s)
- Jeffrey L Segar
- Department of Pediatrics, Cardiovascular Center, University of Iowa, Iowa City, Iowa 52242, USA.
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