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Nicou CM, Passaglia CL. Effect of Ambient Lighting on Intraocular Pressure Rhythms in Rats. Invest Ophthalmol Vis Sci 2024; 65:16. [PMID: 39115866 PMCID: PMC11314632 DOI: 10.1167/iovs.65.10.16] [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: 04/05/2024] [Accepted: 07/21/2024] [Indexed: 08/11/2024] Open
Abstract
Purpose The purpose of this study was to determine the effects of ambient lighting on intraocular pressure (IOP) rhythmicity and variability. Methods IOP was continuously recorded by wireless telemetry from rats under light/dark (LD), dark/light (DL), asymmetric (6L18D and 18D6L), constant dark (DD), and constant light (LL) cycles. In some DD experiments, 1-hour light pulses were presented at varying times. IOP rhythmicity and variability were respectively quantified via cosinor analysis and peak detection algorithms that identified transient and sustained fluctuations. Results Rat IOP peaked at night and troughed during the day with LD amplitude of 8.7 ± 3.4 mm Hg. Rhythmicity persisted in DD and LL with a free-running period of 24.1 ± 0.3 and 25.2 ± 0.4 hours, respectively. Peak-to-trough amplitude was approximately 60% smaller in LL, often disappeared after 1 to 2 weeks as daytime IOP drifted 2.6 ± 1.5 mm Hg higher, and returned to approximately 60% larger in LD. Rhythmicity was similarly impacted but resynchronized to DL over 4 to 6 days. Rhythmicity was unaltered by short photoperiods (6L18D), but the nocturnal IOP elevation was markedly shortened by long photoperiods (18L6D) and temporarily lowered to daytime levels by light pulses during the subjective night. Transient and sustained event rate, amplitude, interval, and energy content were nearly identical in LD, DD, and LL. Conclusions Aqueous humor dynamics of rat eyes are intrinsically configured to set IOP at daytime levels. Circadian clock input modulates these dynamics to elevate IOP at night. Light at night blocks this input, sending IOP back to daytime levels. Effects of abnormal lighting on IOP rhythmicity may contribute to pressure-related ocular neuropathies.
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Affiliation(s)
- Christina M. Nicou
- Medical Engineering Department, University of South Florida, Tampa, Florida, United States
| | - Christopher L. Passaglia
- Medical Engineering Department, University of South Florida, Tampa, Florida, United States
- Ophthalmology Department, University of South Florida, Tampa, Florida, United States
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Toffoli B, Tonon F, Giudici F, Ferretti T, Ghirigato E, Contessa M, Francica M, Candido R, Puato M, Grillo A, Fabris B, Bernardi S. Preliminary Study on the Effect of a Night Shift on Blood Pressure and Clock Gene Expression. Int J Mol Sci 2023; 24:ijms24119309. [PMID: 37298261 DOI: 10.3390/ijms24119309] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/19/2023] [Accepted: 05/24/2023] [Indexed: 06/12/2023] Open
Abstract
Night shift work has been found to be associated with a higher risk of cardiovascular and cerebrovascular disease. One of the underlying mechanisms seems to be that shift work promotes hypertension, but results have been variable. This cross-sectional study was carried out in a group of internists with the aim of performing a paired analysis of 24 h blood pressure in the same physicians working a day shift and then a night shift, and a paired analysis of clock gene expression after a night of rest and a night of work. Each participant wore an ambulatory blood pressure monitor (ABPM) twice. The first time was for a 24 h period that included a 12 h day shift (08.00-20.00) and a night of rest. The second time was for a 30 h period that included a day of rest, a night shift (20.00-08.00), and a subsequent period of rest (08.00-14.00). Subjects underwent fasting blood sampling twice: after the night of rest and after the night shift. Night shift work significantly increased night systolic blood pressure (SBP), night diastolic blood pressure (DBP), and heart rate (HR) and decreased their respective nocturnal decline. Clock gene expression increased after the night shift. There was a direct association between night blood pressure and clock gene expression. Night shifts lead to an increase in blood pressure, non-dipping status, and circadian rhythm misalignment. Blood pressure is associated with clock genes and circadian rhythm misalignement.
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Affiliation(s)
- Barbara Toffoli
- Department of Medical Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
| | - Federica Tonon
- Department of Medical Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
| | - Fabiola Giudici
- Department of Medical Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
| | - Tommaso Ferretti
- Department of Medical Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
| | - Elena Ghirigato
- Department of Medical Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
| | - Matilde Contessa
- Department of Medical Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
| | - Morena Francica
- Department of Medical Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
| | - Riccardo Candido
- Department of Medical Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
- SC Patologie Diabetiche, ASUGI, 34100 Trieste, Italy
| | - Massimo Puato
- SSD Angiologia e Fisiologia Clinica Vascolare Multidisciplinare Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
| | - Andrea Grillo
- Department of Medical Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
- UCO Medicina Clinica, ASUGI Azienda Sanitaria Universitaria Giuliano-Isontina, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
| | - Bruno Fabris
- Department of Medical Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
- UCO Medicina Clinica, ASUGI Azienda Sanitaria Universitaria Giuliano-Isontina, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
| | - Stella Bernardi
- Department of Medical Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
- UCO Medicina Clinica, ASUGI Azienda Sanitaria Universitaria Giuliano-Isontina, Cattinara Teaching Hospital, Strada di Fiume 447, 34149 Trieste, Italy
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Hypotensive effects of melatonin in rats: Focus on the model, measurement, application, and main mechanisms. Hypertens Res 2022; 45:1929-1944. [PMID: 36123396 DOI: 10.1038/s41440-022-01031-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 08/23/2022] [Accepted: 08/25/2022] [Indexed: 11/08/2022]
Abstract
The hypotensive effects of melatonin are based on a negative correlation between melatonin levels and blood pressure in humans. However, there is a positive correlation in nocturnal animals that are often used as experimental models in cardiovascular research, and the hypotensive effects and mechanism of melatonin action are often investigated in rats and mice. In rats, the hypotensive effects of melatonin have been studied in normotensive and spontaneously or experimentally induced hypertensive strains. In experimental animals, blood pressure is often measured indirectly during the light (passive) phase of the day by tail-cuff plethysmography, which has limitations regarding data quality and animal well-being compared to telemetry. Melatonin is administered to rats in drinking water, subcutaneously, intraperitoneally, or microinjected into specific brain areas at different times. Experimental data show that the hypotensive effects of melatonin depend on the experimental animal model, blood pressure measurement technique, and the route, time and duration of melatonin administration. The hypotensive effects of melatonin may be mediated through specific membrane G-coupled receptors located in the heart and arteries. Due to melatonin's lipophilic nature, its potential hypotensive effects can interfere with various regulatory mechanisms, such as nitric oxide and reactive oxygen species production and activation of the autonomic nervous and circadian systems. Based on the research conducted on rats, the cardiovascular effects of melatonin are modulatory, delayed, and indirect.
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Omacor Protects Normotensive and Hypertensive Rats Exposed to Continuous Light from Increased Risk to Malignant Cardiac Arrhythmias. Mar Drugs 2021; 19:md19120659. [PMID: 34940658 PMCID: PMC8709333 DOI: 10.3390/md19120659] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/13/2022] Open
Abstract
Light pollution disturbs circadian rhythm, and this can also be deleterious to the heart by increased susceptibility to arrhythmias. Herein, we investigated if rats exposed to continuous light had altered myocardial gene transcripts and/or protein expression which affects arrhythmogenesis. We then assessed if Omacor® supplementation benefitted affected rats. Male and female spontaneously hypertensive (SHR) and normotensive Wistar rats (WR) were housed under standard 12 h/12 h light/dark cycles or exposed to 6-weeks continuous 300 lux light for 24 h. Half the rats were then treated with 200 mg/100 g b.w. Omacor®. Continuous light resulted in higher male rat vulnerability to malignant ventricular fibrillation (VF). This was linked with myocardial connexin-43 (Cx43) down-regulation and deteriorated intercellular electrical coupling, due in part to increased pro-inflammatory NF-κB and iNOS transcripts and decreased sarcoplasmic reticulum Ca2+ATPase transcripts. Omacor® treatment increased the electrical threshold to induce the VF linked with amelioration of myocardial Cx43 mRNA and Cx43 protein levels and the suppression of NF-κB and iNOS. This indicates that rat exposure to continuous light results in deleterious cardiac alterations jeopardizing intercellular Cx43 channel-mediated electrical communication, thereby increasing the risk of malignant arrhythmias. The adverse effects were attenuated by treatment with Omacor®, thus supporting its potential benefit and the relevance of monitoring omega-3 index in human populations at risk.
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Morphological and Functional Changes of Pituitary GH and PRL Cells Following Prolonged Exposure of Female Rats to Constant Light. SERBIAN JOURNAL OF EXPERIMENTAL AND CLINICAL RESEARCH 2021. [DOI: 10.2478/sjecr-2019-0063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Light regulates numerous physiological functions including secretion of different hormones. Our aim was to determine morphological and functional changes of the pituitary growth hormone (GH) and prolactin (PRL) producing cells in female rats exposed to constant light regime from the peripubertal to adult period of life. Starting from the thirtieth postnatal day, female Wistar rats were exposed to constant light (600 lx) for the following 95 days. Controls were maintained under the regular laboratory lighting conditions. The GH and PRL cells were immunohistochemically visualized. Changes in cell volumes and volume densities were evaluated by stereology. Concentrations of PRL and GH in circulation were also determined. We detected significant decrease of the GH cell volume and volume density, followed by reduced the GH blood concentration in comparison to the controls. In contrast, PRL cells were larger in size and their volume density was significantly increased when compared to the controls. Accordingly, PRL concentration was elevated. It can be concluded that exposure of female rats to constant light regime, from peripubertal to adult period of life, causes inhibition of the pituitary GH and stimulation of PRL cells.
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Bagci S, Sabir H, Müller A, Reiter RJ. Effects of altered photoperiod due to COVID-19 lockdown on pregnant women and their fetuses. Chronobiol Int 2020; 37:961-973. [PMID: 32519912 DOI: 10.1080/07420528.2020.1772809] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Maternal circadian rhythms provide highly important input into the entrainment and programming of fetal and newborn circadian rhythms. The light-dark cycle is an important regulator of the internal biological clock. Even though pregnant women spend a greater part of the day at home during the latter stages of pregnancy, natural light exposure is crucial for the fetus. The current recommended COVID-19 lockdown might dramatically alter normal environmental lighting conditions of pregnant women, resulting in exposure to extremely low levels of natural daylight and high-intensity artificial light sources during both day and night. This article summarizes the potential effects on pregnant woman and their fetuses due to prolonged exposure to altered photoperiod and as consequence altered circadian system, known as chronodisruption, that may result from the COVID-19 lockdown.
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Affiliation(s)
- S Bagci
- Department of Neonatology and Pediatric Intensive Care, Children's Hospital-University of Bonn , Bonn, Germany
| | - H Sabir
- Department of Neonatology and Pediatric Intensive Care, Children's Hospital-University of Bonn , Bonn, Germany
| | - A Müller
- Department of Neonatology and Pediatric Intensive Care, Children's Hospital-University of Bonn , Bonn, Germany
| | - R J Reiter
- Department of Cell Systems and Anatomy, UT Health San Antonio , San Antonio, Texas, USA
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Kuzmenko NV. Seasonal Variations in Atmospheric Pressure, Partial Oxygen Density, and Geomagnetic Activity as Additional Synchronizers of Circannual Rhythms. Biophysics (Nagoya-shi) 2019. [DOI: 10.1134/s0006350919040080] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Baker J, Kimpinski K. Role of melatonin in blood pressure regulation: An adjunct anti-hypertensive agent. Clin Exp Pharmacol Physiol 2018; 45:755-766. [DOI: 10.1111/1440-1681.12942] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/27/2018] [Accepted: 03/21/2018] [Indexed: 12/23/2022]
Affiliation(s)
- Jacquie Baker
- School of Kinesiology; Western University; London ON Canada
- Department of Clinical Neurological Sciences; London Health Sciences Centre; University Hospital; London ON Canada
| | - Kurt Kimpinski
- School of Kinesiology; Western University; London ON Canada
- Department of Clinical Neurological Sciences; London Health Sciences Centre; University Hospital; London ON Canada
- Schulich School of Medicine & Dentistry; Western University; London ON Canada
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Puzserova A, Bernatova I. Blood pressure regulation in stress: focus on nitric oxide-dependent mechanisms. Physiol Res 2017; 65:S309-S342. [PMID: 27775419 DOI: 10.33549/physiolres.933442] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Stress is considered a risk factor associated with the development of various civilization diseases including cardiovascular diseases, malignant tumors and mental disorders. Research investigating mechanisms involved in stress-induced hypertension have attracted much attention of physicians and researchers, however, there are still ambiguous results concerning a causal relationship between stress and long-term elevation of blood pressure (BP). Several studies have observed that mechanisms involved in the development of stress-induced hypertension include increased activity of sympathetic nervous system (SNS), glucocorticoid (GC) overload and altered endothelial function including decreased nitric oxide (NO) bioavailability. Nitric oxide is well known neurotransmitter, neuromodulator and vasodilator involved in regulation of neuroendocrine mechanisms and cardiovascular responses to stressors. Thus NO plays a crucial role in the regulation of the stress systems and thereby in the BP regulation in stress. Elevated NO synthesis, especially in the initial phase of stress, may be considered a stress-limiting mechanism, facilitating the recovery from stress to the resting levels via attenuation of both GC release and SNS activity as well as by increased NO-dependent vasorelaxation. On the other hand, reduced levels of NO were observed in the later phases of stress and in subjects with genetic predisposition to hypertension, irrespectively, in which reduced NO bioavailability may account for disruption of NO-mediated BP regulatory mechanisms and accentuated SNS and GC effects. This review summarizes current knowledge on the role of stress in development of hypertension with a special focus on the interactions among NO and other biological systems affecting blood pressure and vascular function.
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Affiliation(s)
- A Puzserova
- Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Bratislava, Slovak Republic.
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Simko F, Baka T, Paulis L, Reiter RJ. Elevated heart rate and nondipping heart rate as potential targets for melatonin: a review. J Pineal Res 2016; 61:127-37. [PMID: 27264986 DOI: 10.1111/jpi.12348] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 06/03/2016] [Indexed: 01/08/2023]
Abstract
Elevated heart rate is a risk factor for cardiovascular and all-cause mortalities in the general population and various cardiovascular pathologies. Insufficient heart rate decline during the night, that is, nondipping heart rate, also increases cardiovascular risk. Abnormal heart rate reflects an autonomic nervous system imbalance in terms of relative dominance of sympathetic tone. There are only a few prospective studies concerning the effect of heart rate reduction in coronary heart disease and heart failure. In hypertensive patients, retrospective analyses show no additional benefit of slowing down the heart rate by beta-blockade to blood pressure reduction. Melatonin, a secretory product of the pineal gland, has several attributes, which predict melatonin to be a promising candidate in the struggle against elevated heart rate and its consequences in the hypertensive population. First, melatonin production depends on the sympathetic stimulation of the pineal gland. On the other hand, melatonin inhibits the sympathetic system in several ways representing potentially the counter-regulatory mechanism to normalize excessive sympathetic drive. Second, administration of melatonin reduces heart rate in animals and humans. Third, the chronobiological action of melatonin may normalize the insufficient nocturnal decline of heart rate. Moreover, melatonin reduces the development of endothelial dysfunction and atherosclerosis, which are considered a crucial pathophysiological disorder of increased heart rate and pulsatile blood flow. The antihypertensive and antiremodeling action of melatonin along with its beneficial effects on lipid profile and insulin resistance may be of additional benefit. A clinical trial investigating melatonin actions in hypertensive patients with increased heart rate is warranted.
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Affiliation(s)
- Fedor Simko
- Department of Pathophysiology, Faculty of Medicine, Comenius University, Bratislava, Slovak Republic
- 3rd Clinic of Medicine, Faculty of Medicine, Comenius University, Bratislava, Slovak Republic
- Institute of Experimental Endocrinology BMC, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Tomas Baka
- Department of Pathophysiology, Faculty of Medicine, Comenius University, Bratislava, Slovak Republic
| | - Ludovit Paulis
- Department of Pathophysiology, Faculty of Medicine, Comenius University, Bratislava, Slovak Republic
| | - Russel J Reiter
- Department of Cellular and Structural Biology, UT Health Science Center, San Antonio, TX, USA
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Behavioral and molecular effects of prenatal continuous light exposure in the adult rat. Brain Res 2016; 1650:51-59. [PMID: 27566064 DOI: 10.1016/j.brainres.2016.08.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 08/19/2016] [Accepted: 08/22/2016] [Indexed: 12/21/2022]
Abstract
Disruption of the maternal environment during pregnancy leads to behavioral changes and diseases in the adult offspring. To explore the influence of prenatal continuous light exposure (PCLE) on the adult offspring, we exposed pregnant Wistar rats to constant light during late gestation. Adult PCLE offspring showed an anxiety-like behavior and impairment of short-term memory in different tests. Measurements in the whole brain homogenates from newborn and adult offspring indicated decreased melatonin and serotonin levels and increased reactive oxygen species level in PCLE offspring. Further, we determined melatonin-, serotonin-, oxidative stress-, apoptosis-, and circadian system-related genes expression in different brain areas of adult offspring. The serotonin reuptaker Slc6a4 displayed a decreased expression in the prefrontal cortex of PCLE group. The circadian rhythm-related gene Rora was upregulated in the amygdala of PCLE offspring. Our results point to adverse behavioral effects of PCLE on adult offspring, involving serotonin and melatonin signaling dysregulation, increased chronic oxidative stress, and altered gene expression.
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Tao J, Lv J, Li W, Zhang P, Mao C, Xu Z. Exogenous melatonin reduced blood pressure in late-term ovine fetus via MT1/MT2 receptor pathways. Reprod Biol 2016; 16:212-217. [PMID: 27692363 DOI: 10.1016/j.repbio.2016.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 06/02/2016] [Accepted: 06/03/2016] [Indexed: 12/26/2022]
Abstract
Melatonin is involved in the regulation of blood pressure through the receptor dependent or independent route. However, the effect of melatonin on fetal blood pressure is unknown. This study investigated the effect of melatonin on blood pressure of the late-term ovine fetus in utero. Melatonin and/or antagonists were intravenously administered into the fetuses. Mean arterial pressure and heart rate were recorded. Fetal blood samples were analyzed for biochemical parameters and hormones, including cortisol, angiotensin I, angiotensin II, aldosterone, atrial natriuretic peptide, corticotrophin-releasing hormone, adrenocorticotropic hormone, and endothelin. Fetal blood pressure was decreased following administration of melatonin, whereas it was increased following administration of luzindole, but not prazosin. Plasma level of endothelin was decreased by melatonin, which was blocked by luzindole. Our study suggested that melatonin reduced fetal blood pressure via MT1/MT2 receptors and possibly involving release of endothelin.
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Affiliation(s)
- Jianying Tao
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China; Suzhou Municipal Hospital, Suzhou, China
| | - Juanxiu Lv
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Weisheng Li
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Pengjie Zhang
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Caiping Mao
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China
| | - Zhice Xu
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China; Center for Perinatal Biology, Loma Linda University, CA, USA.
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Faraut B, Bayon V, Léger D. Neuroendocrine, immune and oxidative stress in shift workers. Sleep Med Rev 2013; 17:433-44. [DOI: 10.1016/j.smrv.2012.12.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 12/11/2012] [Accepted: 12/20/2012] [Indexed: 10/26/2022]
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Campos LA, Cipolla-Neto J, Michelini LC. Melatonin modulates baroreflex control via area postrema. Brain Behav 2013; 3:171-7. [PMID: 23531786 PMCID: PMC3607157 DOI: 10.1002/brb3.123] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 12/15/2012] [Accepted: 12/23/2012] [Indexed: 11/12/2022] Open
Abstract
Pineal gland and its hormone melatonin have been implicated in modulation of cardiovascular system. We aimed at studying the effects of melatonin on baroreflex sensitivity and the role of area postrema, as a component modulator of baroreflex arch. Mean arterial pressure (MAP) and heart rate (HR) were recorded in conscious freely moving rats. Baroreceptor reflex sensitivity was assessed by determining the HR responses to ramped infusions of phenylephrine (PE) and sodium nitroprusside (SNP)-induced MAP changes. Melatonin bolus (0.11 mg/kg) immediately followed by its continuous infusion (0.43 × 10(-9) mol/L at a rate of 0.65 mL/h for 30 min) in healthy normotensive rats produced a downward shift of baroreceptor reflex control with a substantial inhibition of reflex tachycardia (-32%) and potentiation of reflex bradycardia (+20%). Ablation of area postrema (APX group) induced a sustained decrease of MAP (101 ± 3 vs. 116 ± 3 mmHg, P < 0.05 in comparison with sham rats, respectively). The melatonin-induced alterations of baroreflex function observed in the sham group were abolished in the APX group. We conclude that circulating melatonin can modulate baroreceptor reflex control of HR, thus resetting it toward lower HR values. The modulatory effects of melatonin may be mediated via melatonin receptors in the area postrema, located outside the blood-brain barrier.
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Affiliation(s)
- Luciana A Campos
- São José dos Campos Technology Park, University Camilo Castelo Branco (UNICASTELO) São Paulo, Brazil ; Department of Physiology Institute of Biomedical Sciences, University of Sao Paulo Sao Paulo, Brazil
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Fernando HA, Chin HF, Ton SH, Abdul Kadir K. Stress and Its Effects on Glucose Metabolism and 11β-HSD Activities in Rats Fed on a Combination of High-Fat and High-Sucrose Diet with Glycyrrhizic Acid. J Diabetes Res 2013; 2013:190395. [PMID: 23671857 PMCID: PMC3647599 DOI: 10.1155/2013/190395] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 01/29/2013] [Indexed: 11/17/2022] Open
Abstract
Chronic stress has been shown to have a strong link towards metabolic syndrome (MetS). Glycyrrhizic acid (GA) meanwhile has been shown to improve MetS symptoms caused by an unhealthy diet by inhibiting 11 β -HSD 1. This experiment aimed to determine the effects of continuous, moderate-intensity stress on rats with and without GA intake on systolic blood pressure (SBP) across a 28-day period, as well as glucose metabolism, and 11 β -HSD 1 and 2 activities at the end of the 28-day period. Adaptation to the stressor (as shown by SBP) resulted in no significant defects in glucose metabolism by the end of the experimental duration. However, a weakly significant increase in renal 11 β -HSD 1 and a significant increase in subcutaneous adipose tissue 11 β -HSD 1 activities were observed. GA intake did not elicit any significant benefit in glucose metabolism, indicating that the stress response may block its effects. However, GA-induced improvements in 11 β -HSD activities in certain tissues were observed, although it is uncertain if these effects are manifested after adaptation due to the withdrawal of the stress response. Hence the ability of GA to improve stress-induced disturbances in the absence of adaptation needs to be investigated further.
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Affiliation(s)
- Hamish Alexander Fernando
- Monash University Sunway Campus, Jalan Lagoon Selatan, Bandar Sunway, 46150 Selangor Darul Ehsan, Malaysia
- *Hamish Alexander Fernando: and
| | - Hsien-Fei Chin
- Monash University Sunway Campus, Jalan Lagoon Selatan, Bandar Sunway, 46150 Selangor Darul Ehsan, Malaysia
| | - So Ha Ton
- Monash University Sunway Campus, Jalan Lagoon Selatan, Bandar Sunway, 46150 Selangor Darul Ehsan, Malaysia
- *So Ha Ton:
| | - Khalid Abdul Kadir
- Monash University Sunway Campus, Jalan Lagoon Selatan, Bandar Sunway, 46150 Selangor Darul Ehsan, Malaysia
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Circadian disruption leads to loss of homeostasis and disease. SLEEP DISORDERS 2012; 2011:964510. [PMID: 23471148 PMCID: PMC3581131 DOI: 10.1155/2011/964510] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Revised: 09/22/2011] [Accepted: 11/24/2011] [Indexed: 11/28/2022]
Abstract
The relevance of a synchronized temporal order for adaptation and homeostasis is discussed in this review. We present evidence suggesting that an altered temporal order between the biological clock and external temporal signals leads to disease. Evidence mainly based on a rodent model of “night work” using forced activity during the sleep phase suggests that altered activity and feeding schedules, out of phase from the light/dark cycle, may be the main cause for the loss of circadian synchrony and disease. It is proposed that by avoiding food intake during sleep hours the circadian misalignment and adverse consequences can be prevented. This review does not attempt to present a thorough revision of the literature, but instead it aims to highlight the association between circadian disruption and disease with special emphasis on the contribution of feeding schedules in circadian synchrony.
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Abstract
Left ventricular hypertrophy (LVH), despite its adaptive nature, increases cardiovascular morbidity and mortality. Novel approaches for protection against pathological heart remodelling are presented in this supplement. Melatonin diminishes myocardial fibrosis in rats exposed to continuous light and N-nitro-L-arginine-methyl ester (L-NAME) treatment and reduces production of endothelium-derived constricting factors in L-NAME-induced hypertension. Melatonin, because of its extraordinary antioxidant and scavenging properties, benefits for endothelium and sympatholytic action, may prove to be a useful protective drug against heart remodelling. In hypertension induced by relative aldosteronism, the correction of macro and micronutrient dyshomeostasis appears to act beneficially within pathological myocardial remodelling. Alterations in the signal cascade of pathological myocardial growth, including humoral stimuli, receptors, intracellular messengers or transcriptional factors, may be favourably modified at different levels. Inhibition of nuclear factor kappa B (NF-kappaB) potentiates hypertension development, enhances oxidative load, increases the cross-sectional area of the aorta and reduces nitric oxide (NO) synthase activity in L-NAME hypertension. It is suggested that NF-kappaB may play a protective rather than a deleterious role in the haemodynamically overloaded circulation. Compound 21, a recently developed peptide angiotensin II type 2 (AT2) receptor agonist, offers a novel approach in investigating the role of AT2 receptors in the protection of the hypertensive heart. A novel NO donor, L-419, with its intrinsic protection of NO, improves the entire NO signalling cascade and thus favourably influencing the response of the left ventricle to haemodynamic overload. LVH prevention or regression should be considered a therapeutic success only when, along with hypertrophied mass reduction, an improvement of the heart structure, function, metabolism and electrical stability is achieved.
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Continuous light and L-NAME-induced left ventricular remodelling: different protection with melatonin and captopril. J Hypertens 2010; 28 Suppl 1:S13-8. [DOI: 10.1097/01.hjh.0000388489.28213.08] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Association between white-coat effect and blunted dipping of nocturnal blood pressure. Am J Hypertens 2009; 22:1054-61. [PMID: 19629048 DOI: 10.1038/ajh.2009.133] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND In this study, we assessed whether the white-coat effect (difference between office and daytime blood pressure (BP)) is associated with nondipping (absence of BP decrease at night). METHODS Data were available in 371 individuals of African descent from 74 families selected from a population-based hypertension register in the Seychelles Islands and in 295 Caucasian individuals randomly selected from a population-based study in Switzerland. We used standard multiple linear regression in the Swiss data and generalized estimating equations to account for familial correlations in the Seychelles data. RESULTS The prevalence of systolic and diastolic nondipping (<10% nocturnal BP decrease) and white-coat hypertension (WCH) was respectively 51, 46, and 4% in blacks and 33, 37, and 7% in whites. When white coat effect and nocturnal dipping were taken as continuous variables (mm Hg), systolic (SBP) and diastolic BP (DBP) dipping were associated inversely and independently with white-coat effect (P < 0.05) in both populations. Analogously, the difference between office and daytime heart rate was inversely associated with the difference between daytime and night-time heart rate in the two populations. These results did not change after adjustment for potential confounders. CONCLUSIONS The white-coat effect is associated with BP nondipping. The similar associations between office-daytime values and daytime-night-time values for both BP and heart rate suggest that the sympathetic nervous system might play a role. Our findings also further stress the interest, for clinicians, of assessing the presence of a white-coat effect as a means to further identify patients at increased cardiovascular risk and guide treatment accordingly.
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Castelhano-Carlos MJ, Baumans V. The impact of light, noise, cage cleaning and in-house transport on welfare and stress of laboratory rats. Lab Anim 2009; 43:311-27. [PMID: 19505937 DOI: 10.1258/la.2009.0080098] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Human interaction and physical environmental factors are part of the stimuli presented to laboratory animals everyday, influencing their behaviour and physiology and contributing to their welfare. Certain environmental conditions and routine procedures in the animal facility might induce stress responses and when the animal is unable to maintain its homeostasis in the presence of a particular stressor, the animal's wellbeing is threatened. This review article summarizes several published studies on the impact of environmental factors such as light, noise, cage cleaning and in-house transport on welfare and stress of laboratory rats. The behaviour and physiological responses of laboratory rats to different environmental housing conditions and routine procedures are reviewed. Recommendations on the welfare of laboratory rats and refinements in experimental design are discussed and how these can influence and improve the quality of scientific data.
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Affiliation(s)
- M J Castelhano-Carlos
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
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Campos LA, Plehm R, Cipolla-Neto J, Bader M, Baltatu OC. Altered circadian rhythm reentrainment to light phase shifts in rats with low levels of brain angiotensinogen. Am J Physiol Regul Integr Comp Physiol 2006; 290:R1122-7. [PMID: 16339384 DOI: 10.1152/ajpregu.00703.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, we aimed to investigate the adaptation of blood pressure (BP), heart rate (HR), and locomotor activity (LA) circadian rhythms to light cycle shift in transgenic rats with a deficit in brain angiotensin [TGR(ASrAOGEN)]. BP, HR, and LA were measured by telemetry. After baseline recordings (bLD), the light cycle was inverted by prolonging the light by 12 h and thereafter the dark period by 12 h, resulting in inverted dark-light (DL) or light-dark (LD) cycles. Toward that end, a 24-h dark was maintained for 14 days (free-running conditions). When light cycle was changed from bLD to DL, the acrophases (peak time of curve fitting) of BP, HR, and LA shifted to the new dark period in both SD and TGR(ASrAOGEN) rats. However, the readjustment of the BP and HR acrophases in TGR(ASrAOGEN) rats occurred significantly slower than SD rats. The LA acrophases changed similarly in both strains. When light cycle was changed from DL to LD by prolonging the dark period by 12 h, the reentrainment of BP and LA occurred faster than the previous shift in both strains. The readjustment of the BP and HR acrophases in TGR(ASrAOGEN) rats occurred significantly slower than SD rats. In free-running conditions, the circadian rhythms of the investigated parameters adapted in TGR(ASrAOGEN) and SD rats in a similar manner. These results demonstrate that the brain RAS plays an important role in mediating the effects of light cycle shifts on the circadian variation of BP and HR. The adaptive behavior of cardiovascular circadian rhythms depends on the initial direction of light-dark changes.
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Affiliation(s)
- Luciana A Campos
- Max-Delbrück-Center for Molecular Medicine, Berlin-Buch, Germany
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