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Kulesh V, Vasyutin I, Volkova A, Peskov K, Kimko H, Sokolov V, Alluri R. A tutorial for model-based evaluation and translation of cardiovascular safety in preclinical trials. CPT Pharmacometrics Syst Pharmacol 2024; 13:5-22. [PMID: 37950388 PMCID: PMC10787214 DOI: 10.1002/psp4.13082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 10/25/2023] [Accepted: 10/31/2023] [Indexed: 11/12/2023] Open
Abstract
Assessment of drug-induced effects on the cardiovascular (CV) system remains a critical component of the drug discovery process enabling refinement of the therapeutic index. Predicting potential drug-related unintended CV effects in the preclinical stage is necessary for first-in-human dose selection and preclusion of adverse CV effects in the clinical stage. According to the current guidelines for small molecules, nonclinical CV safety assessment conducted via telemetry analyses should be included in the safety pharmacology core battery studies. However, the manual for quantitative evaluation of the CV safety signals in animals is available only for electrocardiogram parameters (i.e., QT interval assessment), not for hemodynamic parameters (i.e., heart rate, blood pressure, etc.). Various model-based approaches, including empirical pharmacokinetic-toxicodynamic analyses and systems pharmacology modeling could be used in the framework of telemetry data evaluation. In this tutorial, we provide a comprehensive workflow for the analysis of nonclinical CV safety on hemodynamic parameters with a sequential approach, highlight the challenges associated with the data, and propose respective solutions, complemented with a reproducible example. The work is aimed at helping researchers conduct model-based analyses of the CV safety in animals with subsequent translation of the effect to humans seamlessly and efficiently.
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Affiliation(s)
- Victoria Kulesh
- Modeling & Simulation Decisions FZ‐LLCDubaiUnited Arab Emirates
- Research Center of Model‐Informed Drug DevelopmentSechenov First Moscow State Medical UniversityMoscowRussia
| | - Igor Vasyutin
- Modeling & Simulation Decisions FZ‐LLCDubaiUnited Arab Emirates
| | - Alina Volkova
- Modeling & Simulation Decisions FZ‐LLCDubaiUnited Arab Emirates
- Sirius University of Science and TechnologySiriusRussia
| | - Kirill Peskov
- Modeling & Simulation Decisions FZ‐LLCDubaiUnited Arab Emirates
- Research Center of Model‐Informed Drug DevelopmentSechenov First Moscow State Medical UniversityMoscowRussia
- Sirius University of Science and TechnologySiriusRussia
| | - Holly Kimko
- CPQP, CPSS, BioPharmaceuticals R&DAstraZenecaGaithersburgMarylandUSA
| | - Victor Sokolov
- Modeling & Simulation Decisions FZ‐LLCDubaiUnited Arab Emirates
- Sirius University of Science and TechnologySiriusRussia
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Tchekalarova J, Krushovlieva D, Ivanova P, Kortenska L. Spontaneously hypertensive rats vs. Wistar Kyoto and Wistar rats: an assessment of anxiety, motor activity, memory performance, and seizure susceptibility. Physiol Behav 2023:114268. [PMID: 37308045 DOI: 10.1016/j.physbeh.2023.114268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 06/04/2023] [Accepted: 06/09/2023] [Indexed: 06/14/2023]
Abstract
Spontaneously hypertensive rats (SHRs) are widely accepted for modeling essential hypertension and Attention deficit hyperactivity disorder (ADHD). However, data concerning central nervous system changes associated with behavioral responses of this strain and usage of Wistar Kyoto (WKY) rats as controls are confounding. The objective of the present study was to assess the impact of anxiety and motor activity on the cognitive responses of SHRs compared to Wistar and WKY rats. In addition, the role of brain-derived neurotrophic factor (BDNF) in the hippocampus on cognitive behavior and seizure susceptibility in the three strains was evaluated. In Experiment#1, SHR demonstrated impulsive responses in the novelty suppression feeding test accompanied by impaired spatial working and associative memory in the Y maze and object recognition test compared with the Wistar rat but not WKY rats. In addition, the WKY rats exhibited diminished activity compared to Wistar rats in an actimeter. In Experiment#2, the seizure susceptibility was assessed by 3-min electroencephalographic (EEG) recording after two consecutive injections of pentylenetetrazol (PTZ) (20+40 mg/kg). The WKY rats were more vulnerable to rhythmic metrazol activity (RMA) than the Wistar rats. In contrast, Wistar rats were more prone to generalized tonic-clonic seizures (GTCS) than WKY rats and SHRs. Control SHR had lower BDNF expression in the hippocampus compared to Wistar rats. However, while the BDNF levels were elevated in the Wistar and WKY rats after PTZ injection, no change in this signaling molecule was observed in the SHR in the seizure condition. The results suggest Wistar rats as a more appropriate control of SHR than WKY rats for studying memory responses mediated by BDNF in the hippocampus. The higher vulnerability to seizures in Wistar and WKY rats compared to SHR might be linked to PTZ-induced decreased expression of BDNF in the hippocampus.
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Affiliation(s)
- Jana Tchekalarova
- Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria; University of Chemical Technology and Metallurgy, 1756 Sofia, Bulgaria.
| | | | - Petya Ivanova
- Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Lidia Kortenska
- Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
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Mille T, Bonilla A, Guillaud E, Bertrand SS, Menuet C, Cazalets JR. Muscarinic cholinergic modulation of cardiovascular variables in spinal cord injured rats. Exp Neurol 2023; 363:114369. [PMID: 36878399 DOI: 10.1016/j.expneurol.2023.114369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 02/16/2023] [Accepted: 02/28/2023] [Indexed: 03/07/2023]
Abstract
Spinal cord injury (SCI) leads not only to major impairments in sensorimotor control but also to dramatic dysregulation of autonomic functions including major cardiovascular disturbances. Consequently, individuals with SCI endure daily episodic hypo/hypertension and are at increased risk for cardiovascular disease. Several studies have suggested that an intrinsic spinal coupling mechanism between motor and sympathetic neuronal networks exist and that propriospinal cholinergic neurons may be responsible for a synchronized activation of both somatic and sympathetic outputs. We therefore investigated in the present study, the effect of cholinergic muscarinic agonists on cardiovascular parameters in freely moving adult rats after SCI. Female Sprague-Dawley rats were implanted with radiotelemetry sensors for long-term in vivo monitoring of blood pressure (BP). From BP signal, we calculated heart rate (HR) and respiratory frequency. We first characterized the physiological changes occurring after a SCI performed at the T3-T4 level in our experimental model system. We then investigated the effects on BP, HR and respiration, of the muscarinic agonist oxotremorine using one variant that crossed the blood brain barrier (Oxo-S) and one that does not (Oxo-M) in both Pre- and Post-SCI animals. After SCI, both HR and respiratory frequency increased. BP values exhibited an immediate profound drop before progressively increasing over the three-week post-lesion period but remained below control values. A spectral analysis of BP signal revealed the disappearance of the low frequency component of BP (0.3-0.6 Hz) referred to as Mayer waves after SCI. In Post-SCI animals, central effects mediated by Oxo-S led to an increase in HR and MAP, a slowdown in respiratory frequency and to an increased power in the 0.3-0.6 Hz frequency band. This study unravels some of the mechanisms by which muscarinic activation of spinal neurons could contribute to partial restoration of BP after SCI.
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Affiliation(s)
- Théo Mille
- Université de Bordeaux, CNRS UMR 5287, INCIA, Zone nord, Bat 2, 2e étage, 146 rue Léo Saignat, 33076 Bordeaux cedex, France
| | - Aurélie Bonilla
- Université de Bordeaux, CNRS UMR 5287, INCIA, Zone nord, Bat 2, 2e étage, 146 rue Léo Saignat, 33076 Bordeaux cedex, France
| | - Etienne Guillaud
- Université de Bordeaux, CNRS UMR 5287, INCIA, Zone nord, Bat 2, 2e étage, 146 rue Léo Saignat, 33076 Bordeaux cedex, France
| | - Sandrine S Bertrand
- Université de Bordeaux, CNRS UMR 5287, INCIA, Zone nord, Bat 2, 2e étage, 146 rue Léo Saignat, 33076 Bordeaux cedex, France
| | - Clément Menuet
- Institut de Neurobiologie de la Méditerranée, INMED UMR 1249, INSERM, Aix-Marseille Université, Marseille, France
| | - Jean-René Cazalets
- Université de Bordeaux, CNRS UMR 5287, INCIA, Zone nord, Bat 2, 2e étage, 146 rue Léo Saignat, 33076 Bordeaux cedex, France.
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DeLalio LJ, Stocker SD. Impact of anesthesia, sex, and circadian cycle on renal afferent nerve sensitivity. Am J Physiol Heart Circ Physiol 2021; 320:H117-H132. [PMID: 33216622 PMCID: PMC7847066 DOI: 10.1152/ajpheart.00675.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 01/09/2023]
Abstract
Elevated renal afferent nerve (ARNA) activity or dysfunctional reno-renal reflexes via altered ARNA sensitivity contribute to hypertension and chronic kidney disease. These nerves contain mechano- and chemosensitive fibers that respond to ischemia, changes in intrarenal pressures, and chemokines. Most studies have utilized various anesthetized preparations and exclusively male animals to characterize ARNA responses. Therefore, this study assessed the impact of anesthesia, sex, and circadian period on ARNA responses and sensitivity. Multifiber ARNA recordings were performed in male and female Sprague-Dawley rats (250-400 g) and compared across decerebrate versus Inactin, isoflurane, and urethane anesthesia groups. Intrarenal artery infusion of capsaicin (0.1-50.0 μM, 0.05 mL) produced concentration-dependent increases in ARNA; however, the ARNA sensitivity was significantly greater in decerebrate versus Inactin, isoflurane, and urethane groups. Increases in renal pelvic pressure (0-30 mmHg, 30 s) produced pressure-dependent increases in ARNA; however, ARNA sensitivity was again greater in decerebrate and Inactin groups versus isoflurane and urethane. Acute renal artery occlusion (30 s) increased ARNA, but responses did not differ across groups. Analysis of ARNA responses to increased pelvic pressure between male and female rats revealed significant sex differences only in isoflurane and urethane groups. ARNA responses to intrarenal capsaicin infusion were significantly blunted at nighttime versus daytime; however, ARNA responses to increased pelvic pressure or renal artery occlusion were not different between daytime and nighttime. These results demonstrate that ARNA sensitivity is greatest in decerebrate and Inactin-anesthetized groups but was not consistently influenced by sex.NEW & NOTEWORTHY We determined the impact of anesthesia, sex, and circadian cycle on renal afferent nerve (ARNA) sensitivity to chemical and mechanical stimuli. ARNA sensitivity to renal capsaicin infusion was greatest in decerebrate > Inactin > urethane or isoflurane groups. Elevated renal pelvic pressure significantly increased ARNA; decerebrate and Inactin groups exhibited the greatest ARNA sensitivity. Sex differences in renal afferent responses were not consistently observed. Circadian cycle altered chemosensory but not mechanosensory responses.
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Affiliation(s)
- Leon J DeLalio
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Sean D Stocker
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
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Ivanova N, Tchekalarova J. The Potential Therapeutic Capacity of Inhibiting the Brain Renin-Angiotensin System in the Treatment of Co-Morbid Conditions in Epilepsy. CNS Drugs 2019; 33:1101-1112. [PMID: 31680223 DOI: 10.1007/s40263-019-00678-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Epilepsy is one of the most prevalent neurological diseases and although numerous novel anticonvulsants have been approved, the proportion of patients who are refractory to medical treatment of seizures and have progressive co-morbidities such as cognitive impairment and depression remains at about 20-30%. In the last decade, extensive research has identified a therapeutic capacity of the components of the brain renin-angiotensin system (RAS) in seizure- and epilepsy-related phenomena. Alleviating the activity of RAS in the central nervous system is considered to be a potential adjuvant strategy for the treatment of numerous detrimental consequences of epileptogenesis. One of the main advantages of RAS is associated with its modulatory influence on different neurotransmitter systems, thereby exerting a fine-tuning control mechanism for brain excitability. The most recent scientific findings regarding the involvement of the components of brain RAS show that angiotensin II (Ang II), angiotensin-converting enzyme (ACE), Ang II type 1 (AT1) and type 2 (AT2) receptors are involved in the control of epilepsy and its accompanying complications, and therefore they are currently of therapeutic interest in the treatment of this disease. However, data on the role of different components of brain RAS on co-morbid conditions in epilepsy, including hypertension, are insufficient. Experimental and clinical findings related to the involvement of Ang II, ACE, AT1, and AT2 receptors in the control of epilepsy and accompanying complications may point to new therapeutic opportunities and adjuvants for the treatment of common co-morbid conditions of epilepsy.
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Affiliation(s)
- Natasha Ivanova
- Institute of Neurobiology, Bulgarian Academy of Sciences, 23 Acad. G. Bonchev Str., 1113, Sofia, Bulgaria.
| | - Jana Tchekalarova
- Institute of Neurobiology, Bulgarian Academy of Sciences, 23 Acad. G. Bonchev Str., 1113, Sofia, Bulgaria
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Rumanova VS, Okuliarova M, Molcan L, Sutovska H, Zeman M. Consequences of low-intensity light at night on cardiovascular and metabolic parameters in spontaneously hypertensive rats. Can J Physiol Pharmacol 2019; 97:863-871. [DOI: 10.1139/cjpp-2019-0043] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Circadian rhythms are an inherent property of physiological processes and can be disturbed by irregular environmental cycles, including artificial light at night (ALAN). Circadian disruption may contribute to many pathologies, such as hypertension, obesity, and type 2 diabetes, but the underlying mechanisms are not understood. Our study investigated the consequences of ALAN on cardiovascular and metabolic parameters in spontaneously hypertensive rats, which represent an animal model of essential hypertension and insulin resistance. Adult males were exposed to a 12 h light − 12 h dark cycle and the ALAN group experienced dim light at night (1–2 lx), either for 2 or 5 weeks. Rats on ALAN showed a loss of light–dark variability for systolic blood pressure, but not for heart rate. Moreover, a gradual increase of systolic blood pressure was recorded over 5 weeks of ALAN. Exposure to ALAN increased plasma insulin and hepatic triglyceride levels. An increased expression of metabolic transcription factors, Pparα and Pparγ, in the epididymal fat and a decreased expression of Glut4 in the heart was found in the ALAN group. Our results demonstrate that low-intensity ALAN can disturb blood pressure control and augment insulin resistance in spontaneously hypertensive rats, and may represent a serious risk factor for cardiometabolic diseases.
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Affiliation(s)
- Valentina Sophia Rumanova
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Monika Okuliarova
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Lubos Molcan
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Hana Sutovska
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Michal Zeman
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
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Bazilio DS, Bonagamba LGH, Moraes DJA, Machado BH. Cardiovascular and respiratory profiles during the sleep-wake cycle of rats previously submitted to chronic intermittent hypoxia. Exp Physiol 2019; 104:1408-1419. [PMID: 31099915 DOI: 10.1113/ep087784] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 05/15/2019] [Indexed: 12/22/2022]
Abstract
NEW FINDINGS What is the central question of this study? Chronic intermittent hypoxia (CIH) causes increased arterial pressure (AP), sympathetic overactivity and changes in expiratory modulation of sympathetic activity. However, changes in the short-term sleep-wake cycle pattern after CIH and their potential impact on cardiorespiratory parameters have not been reported previously. What is the main finding and its importance? Exposure to CIH for 10 days elevates AP in wakefulness and sleep but does not cause major changes in short-term sleep-wake cycle pattern. A higher incidence of muscular expiratory activity was observed in rats exposed to CIH only during wakefulness, indicating that active expiration is not required for the increase in AP in rats submitted to CIH. ABSTRACT Chronic intermittent hypoxia (CIH) increases arterial pressure (AP) and changes sympathetic-respiratory coupling. However, the alterations in the sleep-wake cycle after CIH and their potential impact on cardiorespiratory parameters remain unknown. Here, we evaluated whether CIH-exposed rats present changes in their short-term sleep-wake cycle pattern and in cardiorespiratory parameters. Male Wistar rats (∼250 g) were divided into CIH and control groups. The CIH rats were exposed to 8 h day-1 of cycles of normoxia (fraction of inspired O2 = 0.208, 5 min) followed by hypoxia (fraction of inspired O2 = 0.06, 30-40 s) for 10 days. One day after CIH, electrocorticographic activity, cervical EMG, AP and heart rate were recorded for 3 h. Plethysmographic recordings were collected for 2 h. A subgroup of control and CIH rats also had the diaphragm and oblique abdominal muscle activities recorded. Chronic intermittent hypoxia did not alter the time for sleep onset, total time awake, durations of rapid eye movement (REM) and non-REM (NREM) sleep and number of REM episodes in the 3 h recordings. However, a significant increase in the duration of REM episodes was observed. The AP and heart rate were increased in all phases of the cycle in rats exposed to CIH. Respiratory frequency and ventilation were similar between groups in all phases, but tidal volume was increased during NREM and REM sleep in rats exposed to CIH. An increase in the incidence of active expiration during wakefulness was observed in rats exposed to CIH. The data show that CIH-related hypertension is not caused by changes in the sleep-wake cycle and suggest that active expiration is not required for the increase in AP in freely moving rats exposed to CIH.
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Affiliation(s)
- Darlan S Bazilio
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Leni G H Bonagamba
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Davi J A Moraes
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Benedito H Machado
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
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Kawamura H, Mitsubayashi H, Ikeda K, Kawakami K, Nabika T. Chronobiological characteristics of locomotor activity in congenic rats (SHRSPwch1.0) and their effects on arterial pressure. Clin Exp Hypertens 2019; 42:43-51. [PMID: 30724620 DOI: 10.1080/10641963.2019.1571598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Hiroshi Kawamura
- MJG Cardiovascular Institute, Blood Pressure Center, Saitama-shi, Japan
| | | | - Katsumi Ikeda
- Pharmacy and Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya-shi, Japan
| | - Kohei Kawakami
- Department of Experimental Animals Interdisciplinary Center for Science Research, Shimane University, Izumo, Japan
| | - Toru Nabika
- Department of Functional Pathology, Shimane University School of Medicine, Izumo, Japan
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Azadbakht MK, Hassanshahi J, Nematbakhsh M. The Role of Angiotensin II Infusion on the Baroreflex Sensitivity and Renal Function in Intact and Bilateral Renal Denervation Rats. Adv Biomed Res 2018; 7:52. [PMID: 29657937 PMCID: PMC5887788 DOI: 10.4103/abr.abr_192_17] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Background The role of renin-angiotensin system (RAS) in communication between renal system and cardiovascular system is extremely important. Baroreflex sensitivity (BRS) index defines as heart rate (HR) alteration versus mean arterial pressure (MAP) change ratio . Sympathetic nerve is arm of the baroreflexes and any change in its activity will lead to change in the BRS. The role of angiotensin II (Ang II) infusion in systemic circulation accompanied with bilateral renal denervation (RDN) on BRS index and renal function was studied. Materials and Methods Seventy-two male and female Wistar rats in 12 groups were anesthetized and catheterized. The alteration of MAP and HR responses to phenylephrine infusion compared to control groups was determined in bilateral RDN rats subjected to treat with Ang II (300 or 1000 ng/kg/min) administration. Results The BRS index was elevated in Ang II-treated non-RDN (normal) male rats gradually and dose dependently (P < 0.05), while this index was significantly different when compared with RDN male rats (P < 0.05). Accordingly, the BRS index was significantly lower in RDN than non-RDN male rats, and such observation was not observed in female rats. The creatinine clearance (insignificantly) and urine flow (significantly; P < 0.05) were decreased in both non-RDN and RDN male and female rats treated with Ang II. In RDN model, the serum nitrite levels were decreased in male and increased in female by Ang II infusion when compared with vehicle infusion. Conclusion The Ang II infusion could increase the BRS index in non-RDN (normal) male rats which is significantly greater than BRS index in RDN rats.
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Affiliation(s)
- Mohammad Karim Azadbakht
- Water and Electrolytes Research Center/Department of Physiology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Jalal Hassanshahi
- Water and Electrolytes Research Center/Department of Physiology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mehdi Nematbakhsh
- Water and Electrolytes Research Center/Department of Physiology, Isfahan University of Medical Sciences, Isfahan, Iran
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Chronic Blockade of Brain Endothelin Receptor Type-A (ET A) Reduces Blood Pressure and Prevents Catecholaminergic Overactivity in the Right Olfactory Bulb of DOCA-Salt Hypertensive Rats. Int J Mol Sci 2018; 19:ijms19030660. [PMID: 29495426 PMCID: PMC5877521 DOI: 10.3390/ijms19030660] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/05/2018] [Accepted: 02/08/2018] [Indexed: 01/06/2023] Open
Abstract
Overactivity of the sympathetic nervous system and central endothelins (ETs) are involved in the development of hypertension. Besides the well-known brain structures involved in the regulation of blood pressure like the hypothalamus or locus coeruleus, evidence suggests that the olfactory bulb (OB) also modulates cardiovascular function. In the present study, we evaluated the interaction between the endothelinergic and catecholaminergic systems in the OB of deoxycorticosterone acetate (DOCA)-salt hypertensive rats. Following brain ET receptor type A (ETA) blockade by BQ610 (selective antagonist), transcriptional, traductional, and post-traductional changes in tyrosine hydroxylase (TH) were assessed in the OB of normotensive and DOCA-salt hypertensive rats. Time course variations in systolic blood pressure and heart rate were also registered. Results showed that ETA blockade dose dependently reduced blood pressure in hypertensive rats, but it did not change heart rate. It also prevented the increase in TH activity and expression (mRNA and protein) in the right OB of hypertensive animals. However, ETA blockade did not affect hemodynamics or TH in normotensive animals. Present results support that brain ETA are not involved in blood pressure regulation in normal rats, but they significantly contribute to chronic blood pressure elevation in hypertensive animals. Changes in TH activity and expression were observed in the right but not in the left OB, supporting functional asymmetry, in line with previous studies regarding cardiovascular regulation. Present findings provide further evidence on the role of ETs in the regulation of catecholaminergic activity and the contribution of the right OB to DOCA-salt hypertension.
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Emans TW, Janssen BJ, Joles JA, Krediet CTP. Circadian Rhythm in Kidney Tissue Oxygenation in the Rat. Front Physiol 2017; 8:205. [PMID: 28428757 PMCID: PMC5382217 DOI: 10.3389/fphys.2017.00205] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 03/20/2017] [Indexed: 11/13/2022] Open
Abstract
Blood pressure, renal hemodynamics, electrolyte, and water excretion all display diurnal oscillation. Disturbance of these patterns is associated with hypertension and chronic kidney disease. Kidney oxygenation is dependent on oxygen delivery and consumption that in turn are determined by renal hemodynamics and metabolism. We hypothesized that kidney oxygenation also demonstrates 24-h periodicity. Telemetric oxygen-sensitive carbon paste electrodes were implanted in Sprague-Dawley rats (250–300 g), either in renal medulla (n = 9) or cortex (n = 7). Arterial pressure (MAP) and heart rate (HR) were monitored by telemetry in a separate group (n = 8). Data from 5 consecutive days were analyzed for rhythmicity by cosinor analysis. Diurnal electrolyte excretion was assessed by metabolic cages. During lights-off, oxygen levels increased to 105.3 ± 2.1% in cortex and 105.2 ± 3.8% in medulla. MAP was 97.3 ± 1.5 mmHg and HR was 394.0 ± 7.9 bpm during lights-off phase and 93.5 ± 1.3 mmHg and 327.8 ± 8.9 bpm during lights-on. During lights-on, oxygen levels decreased to 94.6 ± 1.4% in cortex and 94.2 ± 8.5% in medulla. There was significant 24-h periodicity in cortex and medulla oxygenation. Potassium excretion (1,737 ± 779 vs. 895 ± 132 μmol/12 h, P = 0.005) and the distal Na+/K+ exchange (0.72 ± 0.02 vs. 0.59 ± 0.02 P < 0.001) were highest in the lights-off phase, this phase difference was not found for sodium excretion (P = 0.4). It seems that oxygen levels in the kidneys follow the pattern of oxygen delivery, which is known to be determined by renal blood flow and peaks in the active phase (lights-off).
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Affiliation(s)
- Tonja W Emans
- Department of Internal Medicine, Academic Medical Center at the University of AmsterdamAmsterdam, Netherlands.,Department of Nephrology and Hypertension, University Medical Center UtrechtUtrecht, Netherlands
| | - Ben J Janssen
- Department of Pharmacology and Toxicology, Maastricht UniversityMaastricht, Netherlands
| | - Jaap A Joles
- Department of Nephrology and Hypertension, University Medical Center UtrechtUtrecht, Netherlands
| | - C T Paul Krediet
- Department of Internal Medicine, Academic Medical Center at the University of AmsterdamAmsterdam, Netherlands
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Lai CT, Chen CY, Kuo TBJ, Chern CM, Yang CCH. Sympathetic Hyperactivity, Sleep Fragmentation, and Wake-Related Blood Pressure Surge During Late-Light Sleep in Spontaneously Hypertensive Rats. Am J Hypertens 2016; 29:590-7. [PMID: 26350298 DOI: 10.1093/ajh/hpv154] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Accepted: 08/13/2015] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Many cardiovascular disease events occur before morning awaking and are more severe in hypertensive patients. Sleep-related cardiovascular regulation has been suggested to play an important role in the pathogenesis. In this study, we explored whether such impairments are exaggerated during late sleep (before the active phase) in spontaneously hypertensive rats (SHRs). METHODS Polysomnographic recording was performed through wireless transmission in freely moving SHRs and Wistar-Kyoto rats (WKYs) over 24 hours. The SHRs were injected with saline and an α1-adrenergic antagonist (prazosin: 5 mg/kg) on 2 separate days. Cardiovascular and autonomic functions were assessed by cardiovascular variability and spontaneous baroreflex analysis. RESULTS Compared with the early-light period (Zeitgeber time (ZT) 0-6 hours), both the WKYs and SHRs during the late-light period (ZT 6-12 hours) showed sleep fragmentation, sympathovagal imbalance, and baroreflex impairment, which were exaggerated and more advanced in the SHRs. Like the morning blood pressure (BP) surge in humans, we found that there was a wake-related blood pressure surge (WBPS) during the late-light period in both groups of rats. The WBPS was also greater and occurred earlier in the SHRs, and was accompanied by a surge in vascular sympathetic index. Under α1-adrenergic antagonism, the late-light period-related sleep fragmentation and BP surge in the SHRs were partially reversed. CONCLUSIONS Our results reveal that sleep-related sympathetic overactivity, baroreflex sensitivity impairment, WBPS, and sleep fragmentation in SHRs deteriorates during the late-light period can be partially alleviated by treatment with an α1-adrenoceptor antagonist.
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Affiliation(s)
- Chun-Ting Lai
- Sleep Research Center, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Chun-Yu Chen
- Sleep Research Center, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Terry B J Kuo
- Sleep Research Center, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan; Brain Research Center, National Yang-Ming University, Taipei, Taiwan; Department of Education and Research, Taipei City Hospital, Taipei, Taiwan; Research Center for Adaptive Data Analysis, National Central University, Taoyuan, Taiwan; Chief of Division of Translational Medicine, Stroke & Neurovascular Center, Veterans General Hospital, Taipei, Taiwan
| | - Chang-Ming Chern
- Sleep Research Center, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan; Chief of Division of Translational Medicine, Stroke & Neurovascular Center, Veterans General Hospital, Taipei, Taiwan
| | - Cheryl C H Yang
- Sleep Research Center, National Yang-Ming University, Taipei, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan; Brain Research Center, National Yang-Ming University, Taipei, Taiwan; Department of Education and Research, Taipei City Hospital, Taipei, Taiwan;
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13
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Kovács L, Kézér FL, Ruff F, Szenci O. Cardiac autonomic activity has a circadian rhythm in summer but not in winter in non-lactating pregnant dairy cows. Physiol Behav 2015; 155:56-65. [PMID: 26639202 DOI: 10.1016/j.physbeh.2015.11.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 11/26/2015] [Indexed: 12/20/2022]
Abstract
This investigation was conducted to examine circadian and seasonal rhythms of heart rate and heart rate variability (HRV) by means of hour-by-hour recordings over 24h in a large population of non-lactating Holstein-Friesian pregnant cows [N=56, summer (June-July); N=61, winter (November-December)]. Data were collected during a 5-day period from each animal. Besides parameters of cardiac autonomic function [the high-frequency (HF) component of HRV and the ratio between the low-frequency (LF) and the HF components (LF/HF ratio)], the RR triangular index and Lmax were calculated. A clear circadian profile was observed for every parameter in summer. Heart rate elevated gradually with the course of the day from 7:00 to 17:00 o'clock and then slightly decreased from 18:00 to 6:00. Sympathovagal balance shifted towards sympathetic dominance during the daytime (increased LF/HF ratio), whereas parasympathetic activity was predominant during the night (increased HF). Lmax reflected a chaotic behavior of heart rate fluctuations during the afternoon in summer. Decreased values of RR triangular index indicated a sensitive period for cows between 14:00 and 16:00 o'clock in summer. During winter, except for the RR triangular (RRtri) index reflecting a high overall variability in R-R intervals between 12:00 and 23:00 o'clock, heart rate and HRV showed no periodicity over the 24-h period. The results suggest an impaired cardiac autonomic function during daytime in summer. HF, Lmax and RRtri index showed seasonal differences for both daytime and nighttime. Heart rate was higher in summer than in winter during the daytime, whereas the LF/HF ratio was higher in winter during the nighttime. Circadian and seasonal rhythms of cardiovascular function are presumably related to the differing temperature, and animal activity associated with summer and winter. As all of the investigated parameters are commonly used in bovine HRV research, these findings have practical implications for behavioral, physiological and welfare studies on dairy cattle.
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Affiliation(s)
- Levente Kovács
- MTA-SZIE Large Animal Clinical Research Group, Üllő-Dóra Major H-2225, Hungary; Institute of Animal Husbandry, Faculty of Agricultural and Environmental Science, Szent István University, Páter Károly utca 1, Gödöllő H-2100, Hungary.
| | - Fruzsina Luca Kézér
- MTA-SZIE Large Animal Clinical Research Group, Üllő-Dóra Major H-2225, Hungary; Institute of Animal Husbandry, Faculty of Agricultural and Environmental Science, Szent István University, Páter Károly utca 1, Gödöllő H-2100, Hungary
| | - Ferenc Ruff
- Department of Methodology, Hungarian Central Statistical Office, Keleti Károly utca 5-7, Budapest H-1024, Hungary
| | - Ottó Szenci
- MTA-SZIE Large Animal Clinical Research Group, Üllő-Dóra Major H-2225, Hungary; Szent István University, Faculty of Veterinary Science, Department and Clinic for Production Animals, Üllő-Dóra Major H-2225, Hungary
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Zaretsky DV, Zaretskaia MV, DiMicco JA. Characterization of the relationship between spontaneous locomotor activity and cardiovascular parameters in conscious freely moving rats. Physiol Behav 2015; 154:60-7. [PMID: 26603274 DOI: 10.1016/j.physbeh.2015.11.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 11/16/2015] [Accepted: 11/17/2015] [Indexed: 10/22/2022]
Abstract
In freely behaving rats, variations in heart rate (HR) and blood pressure (BP) are coupled closely with changes in locomotor activity (Act). We have attempted to characterize this relationship mathematically. In 10- and 16-week-old rats, HR, BP and Act were recorded telemetrically every minute for 2 days under 12h:12h light-dark cycling. After examining data for individual rats, we found that the relationship between Act and HR could be approximated by the negative exponential function HR(Act)=HRmax-(HRmax-HRmin)∗exp(-Act/Acte), where HRmax, HRmin, and Acte are constants. These constants were calculated separately for light and dark periods by non-linear curve fitting. HR corresponding to maximal locomotion was similar during the light and dark phases, while HR at rest during the dark phase was higher than during the light phase. The range of HR variability associated with Act during the dark phase was similar in young and older animals, but minimal HR was significantly lower in older rats. The relationship between Act and BP was approximated with a similar function. We have found no differences between BP at rest and at maximal locomotion between light and dark and between 10-week and 16-week-old rats. Our results indicate that in rats, cardiovascular parameters are coupled to locomotion to a high degree; however both the HR and the BP reach maximal values when locomotor activity is relatively low. We also found that the phase of daily cycle affects HR in conscious rats independent of locomotor activity.
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Affiliation(s)
- Dmitry V Zaretsky
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
| | - Maria V Zaretskaia
- Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Joseph A DiMicco
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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15
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Choy JS, Zhang ZD, Pitsillides K, Sosa M, Kassab GS. Longitudinal hemodynamic measurements in swine heart failure using a fully implantable telemetry system. PLoS One 2014; 9:e103331. [PMID: 25119289 PMCID: PMC4131878 DOI: 10.1371/journal.pone.0103331] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 07/01/2014] [Indexed: 11/19/2022] Open
Abstract
Chronic monitoring of heart rate, blood pressure, and flow in conscious free-roaming large animals can offer considerable opportunity to understand the progression of cardiovascular diseases and can test new diagnostics and therapeutics. The objective of this study was to demonstrate the feasibility of chronic, simultaneous measurement of several hemodynamic parameters (left ventricular pressure, systemic pressure, blood flow velocity, and heart rate) using a totally implantable multichannel telemetry system in swine heart failure models. Two solid-state blood pressure sensors were inserted in the left ventricle and the descending aorta for pressure measurements. Two Doppler probes were placed around the left anterior descending (LAD) and the brachiocephalic arteries for blood flow velocity measurements. Electrocardiographic (ECG) electrodes were attached to the surface of the left ventricle to monitor heart rate. The telemeter body was implanted in the right side of the abdomen under the skin for approximately 4 to 6 weeks. The animals were subjected to various heart failure models, including volume overload (A-V fistula, n = 3), pressure overload (aortic banding, n = 2) and dilated cardiomyopathy (pacing-induced tachycardia, n = 3). Longitudinal changes in hemodynamics were monitored during the progression of the disease. In the pacing-induced tachycardia animals, the systemic blood pressure progressively decreased within the first 2 weeks and returned to baseline levels thereafter. In the aortic banding animals, the pressure progressively increased during the development of the disease. The pressure in the A-V fistula animals only showed a small increase during the first week and remained stable thereafter. The results demonstrated the ability of this telemetry system of long-term, simultaneous monitoring of blood flow, pressure and heart rate in heart failure models, which may offer significant utility for understanding cardiovascular disease progression and treatment.
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Affiliation(s)
- Jenny S. Choy
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Zhen-Du Zhang
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | | | - Margo Sosa
- Transonic Systems Inc., Ithaca, New York, United States of America
| | - Ghassan S. Kassab
- Department of Biomedical Engineering, Indiana University Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- Department of Surgery, Indiana University, Indianapolis, Indiana, United States of America
- Department of Cellular and Integrative Physiology, Indiana University, Indianapolis, Indiana, United States of America
- * E-mail:
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16
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Petkova Z, Tchekalarova J, Pechlivanova D, Moyanova S, Kortenska L, Mitreva R, Popov D, Markova P, Lozanov V, Atanasova D, Lazarov N, Stoynev A. Treatment with melatonin after status epilepticus attenuates seizure activity and neuronal damage but does not prevent the disturbance in diurnal rhythms and behavioral alterations in spontaneously hypertensive rats in kainate model of temporal lobe epilepsy. Epilepsy Behav 2014; 31:198-208. [PMID: 24440891 DOI: 10.1016/j.yebeh.2013.12.013] [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: 10/23/2013] [Revised: 11/14/2013] [Accepted: 12/15/2013] [Indexed: 11/16/2022]
Abstract
Melatonin is involved in the control of circadian and seasonal rhythmicity, possesses potent antioxidant activity, and exerts a neuroprotective and anticonvulsant effect. Spontaneously hypertensive rats (SHRs) are widely accepted as an experimental model of essential hypertension with hyperactivity, deficient sustained attention, and alterations in circadian autonomic profiles. The purpose of the present study was to determine whether melatonin treatment during epileptogenesis can prevent the deleterious consequences of status epilepticus (SE) in SHRs in the kainate (KA) model of temporal lobe of epilepsy (TLE). Spontaneous recurrent seizures (SRSs) were EEG- and video-recorded during and after the treatment protocol. Melatonin (10mg/kg diluted in drinking water, 8weeks) increased the seizure-latent period, decreased the frequency of SRSs, and attenuated the circadian rhythm of seizure activity in SHRs. However, melatonin was unable to affect the disturbed diurnal rhythms and behavioral changes associated with epilepsy, including the decreased anxiety level, depression, and impaired spatial memory. Melatonin reduced neuronal damage specifically in the CA1 area of the hippocampus and piriform cortex and decreased hippocampal serotonin (5-HT) levels both in control and epileptic SHRs. Although long-term melatonin treatment after SE shows a potential to attenuate seizure activity and neuronal loss, it is unable to restore epilepsy-associated behavioral abnormalities in SHRs.
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Affiliation(s)
- Zlatina Petkova
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Jana Tchekalarova
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria.
| | - Daniela Pechlivanova
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Slavianka Moyanova
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Lidia Kortenska
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Rumiana Mitreva
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Deyan Popov
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Petya Markova
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Valentin Lozanov
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Dimitrina Atanasova
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Nikolai Lazarov
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Alexander Stoynev
- Institute of Neurobiology, Acad. G. Bonchev Str., Bl. 23, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
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17
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Sládek M, Polidarová L, Nováková M, Parkanová D, Sumová A. Early chronotype and tissue-specific alterations of circadian clock function in spontaneously hypertensive rats. PLoS One 2012; 7:e46951. [PMID: 23056539 PMCID: PMC3462770 DOI: 10.1371/journal.pone.0046951] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 09/07/2012] [Indexed: 12/31/2022] Open
Abstract
Malfunction of the circadian timing system may result in cardiovascular and metabolic diseases, and conversely, these diseases can impair the circadian system. The aim of this study was to reveal whether the functional state of the circadian system of spontaneously hypertensive rats (SHR) differs from that of control Wistar rat. This study is the first to analyze the function of the circadian system of SHR in its complexity, i.e., of the central clock in the suprachiasmatic nuclei (SCN) as well as of the peripheral clocks. The functional properties of the SCN clock were estimated by behavioral output rhythm in locomotor activity and daily profiles of clock gene expression in the SCN determined by in situ hybridization. The function of the peripheral clocks was assessed by daily profiles of clock gene expression in the liver and colon by RT-PCR and in vitro using real time recording of Bmal1-dLuc reporter. The potential impact of the SHR phenotype on circadian control of the metabolic pathways was estimated by daily profiles of metabolism-relevant gene expression in the liver and colon. The results revealed that SHR exhibited an early chronotype, because the central SCN clock was phase advanced relative to light/dark cycle and the SCN driven output rhythm ran faster compared to Wistar rats. Moreover, the output rhythm was dampened. The SHR peripheral clock reacted to the dampened SCN output with tissue-specific consequences. In the colon of SHR the clock function was severely altered, whereas the differences are only marginal in the liver. These changes may likely result in a mutual desynchrony of circadian oscillators within the circadian system of SHR, thereby potentially contributing to metabolic pathology of the strain. The SHR may thus serve as a valuable model of human circadian disorders originating in poor synchrony of the circadian system with external light/dark regime.
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Affiliation(s)
- Martin Sládek
- Department of Neurohumoral Regulations, Institute of Physiology Academy of Sciences of the Czech Republic v.v.i., Prague, Czech Republic
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18
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Höglund K, Hanås S, Carnabuci C, Ljungvall I, Tidholm A, Häggström J. Blood Pressure, Heart Rate, and Urinary Catecholamines in Healthy Dogs Subjected to Different Clinical Settings. J Vet Intern Med 2012; 26:1300-8. [DOI: 10.1111/j.1939-1676.2012.00999.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 06/15/2012] [Accepted: 08/13/2012] [Indexed: 11/27/2022] Open
Affiliation(s)
- K. Höglund
- Department of Anatomy, Physiology and Biochemistry; Swedish University of Agricultural Sciences; Uppsala; Sweden
| | - S. Hanås
- Strömsholm Specialist Animal Hospital Dog and Cat; Strömsholm; Sweden
| | - C. Carnabuci
- Department of Clinical Sciences; Swedish University of Agricultural Sciences; Uppsala; Sweden
| | - I. Ljungvall
- Department of Clinical Sciences; Swedish University of Agricultural Sciences; Uppsala; Sweden
| | - A. Tidholm
- Albano Animal Hospital; Danderyd; Sweden
| | - J. Häggström
- Department of Clinical Sciences; Swedish University of Agricultural Sciences; Uppsala; Sweden
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Carnevali L, Bondarenko E, Sgoifo A, Walker FR, Head GA, Lukoshkova EV, Day TA, Nalivaiko E. Metyrapone and fluoxetine suppress enduring behavioral but not cardiac effects of subchronic stress in rats. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1123-31. [PMID: 21795640 DOI: 10.1152/ajpregu.00273.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In humans, chronic stressors have long been recognized as potential causes for cardiac dysregulation. Despite this, the underlying mechanistic links responsible for this association are still poorly understood. The purpose of this study was to determine whether exposure to a paradigm of subchronic stress can provoke enduring changes on the heart rate of experimental rats and, if so, to reveal the autonomic and neural mechanisms that mediate these effects. The study was conducted on adult male Sprague-Dawley rats instrumented for telemetric recording of heart rate and locomotor activity. Animals were submitted to a subchronic stress protocol, consisting of a 1-h foot shock session on five consecutive days. Heart rate and locomotor activity were recorded continuously for 3 days before and for 6 days after the subchronic stress period. Subchronic foot shock produced significant and enduring reduction in heart rate both during the dark/active [Δ= -23 ± 3 beats per minute (bpm)] and light/inactive (Δ= -20 ± 3 bpm) phases of the circadian cycle, and a reduction in locomotor activity during the dark/active phase [Δ= -54 ± 6 counts per hour (cph)]. The bradycardic effect of subchronic stress was not related to a reduced locomotion. Selective sympathetic (atenolol) and vagal (methyl-scopolamine) blockades were performed to reveal which autonomic component was responsible for this effect. We found that the fall in heart rate persisted after subchronic stress in animals treated with atenolol (active phase Δ= -16 ± 3 bpm, inactive phase Δ= -19 ± 2 bpm), whereas vagal blockade with scopolamine transiently prevented this effect, suggesting that the bradycardia following subchronic stress was predominantly vagally mediated. Fluoxetine (selective serotonin reuptake inhibitor) and metyrapone (inhibitor of corticosterone synthesis) treatments did not affect heart rate changes but prevented the reduction in locomotion. We conclude that subchronic stress exposure in rats reduces heart rate via a rebound in vagal activation and that this effect is serotonin- and corticosterone-independent.
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Affiliation(s)
- Luca Carnevali
- Dipartimento di Biologia Evolutiva e Funzionale, Universitàdi Parma, Parma, Italy
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20
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Beerling W, Koolhaas JM, Ahnaou A, Bouwknecht JA, de Boer SF, Meerlo P, Drinkenburg WHIM. Physiological and hormonal responses to novelty exposure in rats are mainly related to ongoing behavioral activity. Physiol Behav 2011; 103:412-20. [PMID: 21406199 DOI: 10.1016/j.physbeh.2011.03.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 03/09/2011] [Accepted: 03/09/2011] [Indexed: 10/18/2022]
Abstract
Stress research has been dominated by a circular type of reasoning that occurrence of a stress response is bad. Consequently, the stimulus is often interpreted as stressful in terms of aversiveness involving uncontrollability and unpredictability, which may have maladaptive and pathological consequences. However, the hypothalamic-pituitary-adrenal (HPA) axis and sympathico-adrenomedullary (SAM) system are not only activated in response of the organism to challenges, but also prepare and support the body for behavior. Therefore, a considerable part of the physiological and hormonal responses to a certain situation can be a direct reflection of the metabolic requirements for the normal ongoing behavioral activity, rather than of the stressful nature. In order to clarify this, behavioral, physiological, hormonal and electroencephalographic (EEG) responses to novel cage exposure were studied in male Sprague-Dawley rats. Forced confrontation with a novel cage has been interpreted as a psychological and aversive stressor. However, this interpretation is simply based on the occurrence of a stress response. This study aimed at detailed analysis of the time course of the novelty-induced responses. Different parameters were measured simultaneously in freely moving rats, which allowed correlational comparisons. Hereto, radio telemetry using a small implantable transmitter combined with permanent catheters and an automated blood sampling system was used. A camera placed above the cage allowed behavioral observations. The results show that novelty exposure induced significant increases in locomotor activity, heart rate, blood pressure and plasma corticosterone together with a complete lack of sleep as compared to the undisturbed control situation. The latency to reach significance and the duration of responses varied across parameters but all had recovered within 30min after termination of novelty. The behavioral activity (locomotor activity and EEG wakefulness duration) response pattern was significantly correlated with that of heart rate, blood pressure and plasma corticosterone. Behavioral observations showed mainly explorative behavior in response to novelty. Therefore, the present results indicate that the novelty-induced physiological and hormonal responses are closely related to the ongoing, mainly explorative behavioral activity induced by novelty. An interpretation in terms of metabolic support of ongoing behavior seems to be more appropriate than the frequently used stress interpretation. The present study also emphasizes the added value of simultaneous assessment of behavioral, physiological and hormonal parameters under controlled, non-confounding conditions.
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Affiliation(s)
- W Beerling
- Department of Neuroscience, Janssen Research & Development, a division of Janssen Pharmaceutica NV, Turnhoutseweg 30, 2340 Beerse, Belgium.
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Tchekalarova J, Pechlivanova D, Atanasova T, Markova P, Lozanov V, Stoynev A. Diurnal variations in depression-like behavior of Wistar and spontaneously hypertensive rats in the kainate model of temporal lobe epilepsy. Epilepsy Behav 2011; 20:277-85. [PMID: 21277833 DOI: 10.1016/j.yebeh.2010.12.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 12/14/2010] [Accepted: 12/14/2010] [Indexed: 11/26/2022]
Abstract
The purpose of this study was to explore whether the kainate (KA) model of temporal lobe epilepsy (TLE) can be used as a model of comorbid epilepsy and depression to study diurnal behavioral variations in rats. Development of chronic epilepsy was confirmed by the detection of spontaneous motor seizures (SMS) with video monitoring (24 hours/3-5 months after status epilepticus [SE]). KA-treated spontaneously hypertensive rats (SHRs) exhibited higher seizure frequency than Wistar rats during the light phase in the fourth and fifth months after SE. Although epileptic Wistar rats showed depression-like behavior and reduced anxiety mostly during the light phase, there were no diurnal variations in depression-like patterns in SHRs. Anxiety levels of control and epileptic SHRs were similar. Decreases in serotonin, tryptophan, and dopamine concentrations in the hippocampus were detected in epileptic Wistar rats compared with naive controls. However, monoamine levels of epileptic SHRs were close to those of their controls. Wistar rats and SHRs develop stable depression-like behavior during the chronic epileptic phase with strain-dependent diurnal differences.
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Affiliation(s)
- Jana Tchekalarova
- Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
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22
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Tchekalarova J, Pechlivanova D, Itzev D, Lazarov N, Markova P, Stoynev A. Diurnal rhythms of spontaneous recurrent seizures and behavioral alterations of Wistar and spontaneously hypertensive rats in the kainate model of epilepsy. Epilepsy Behav 2010; 17:23-32. [PMID: 20006556 DOI: 10.1016/j.yebeh.2009.11.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Revised: 11/02/2009] [Accepted: 11/03/2009] [Indexed: 10/20/2022]
Abstract
Attention deficit hyperactivity disorder (ADHD) can coexist with epilepsy. Spontaneously hypertensive rats (SHRs) are considered to model ADHD with overactivity, impulsiveness, deficient sustained attention, and alterations in circadian autonomic profiles. The present study explored spontaneous recurrent seizures (SRSs) and behavioral diurnal activity rhythms in normotensive Wistar rats and SHRs in the kainate model of epilepsy. Rats were video monitored (24 h/3 months) to detect SRSs. SHRs manifested a lower seizure frequency during the light phase in the 8th and 10th weeks and a lower frequency of SRSs during the night phase accompanied by attenuated responses in hyperexcitability tests. Both epileptic strains were hyperactive, with lower anxiety levels, and their diurnal rhythms were abolished. Epileptic Wistar rats and SHRs exhibited less exploration during the dark phase. This study suggests that SHRs may be useful in modeling some aspects (particularly hypertension-related diurnal rhythm disturbance) of behavior associated with epilepsy.
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Affiliation(s)
- Jane Tchekalarova
- Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
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Circadian phase and sex effects on depressive/anxiety-like behaviors and HPA axis responses to acute stress. Physiol Behav 2009; 99:276-85. [PMID: 19932127 DOI: 10.1016/j.physbeh.2009.11.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Revised: 11/03/2009] [Accepted: 11/09/2009] [Indexed: 01/21/2023]
Abstract
Circadian dysregulation in sleep pattern, mood, and hypothalamic-pituitary-adrenal (HPA) axis activity, often occurring in a sexually dimorphic manner, are characteristics of depression. However, the inter-relationships among circadian phase, HPA function, and depressive-like behaviors are not well understood. We investigated behavioral and neuroendocrine correlates of depressive/anxiety-like responses during diurnal ('light') and nocturnal ('dark') phases of the circadian rhythm in the open field (OF), elevated plus maze (EPM), forced swim (FST), and sucrose contrast (SC) tests. Plasma corticosterone (CORT) was measured after a) acute restraint and OF testing and b) FST. Both phase and sex significantly influenced behavioral responses to stress. Males were more anxious than females on the EPM in the light but not the dark phase. Further, the open:closed arm ratio was lower in the dark for females, but not males. By contrast, in the FST, females showed more "despair" (immobility) when tested in the dark, while phase did not affect males. Acute restraint stress increased OF activity in the light, but not the dark, phase. CORT levels were increased in both sexes following the FST, and in males and light phase females post-OF. As expected, females had higher CORT levels than males, even at rest, and this effect was more pronounced in the dark phase. Together, our data highlight the sexually dimorphic influences of circadian phase and stress on behavioral and hormonal responsiveness.
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Kemppinen N, Hau J, Meller A, Mauranen K, Kohila T, Nevalainen T. Impact of aspen furniture and restricted feeding on activity, blood pressure, heart rate and faecal corticosterone and immunoglobulin A excretion in rats (Rattus norvegicus) housed in individually ventilated cages. Lab Anim 2009; 44:104-12. [PMID: 19854757 DOI: 10.1258/la.2009.009058] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study aims to evaluate the impact of adding different items in individually ventilated rat cages on the animal's activity, cardiovascular parameters and faecal stress indicators. The following three cage items made of aspen were compared: a cross made of two intersecting boards, a similar cross where drilled holes were loaded with food pellets (restricted feeding) and a rectangular tube. Male rats of the strains BN and F344 (n = 12) were housed in groups of three; one rat in each group was implanted with a telemetric transponder to measure mean arterial pressure (MAP) and heart rate (HR). In a crossover design, each group spent 14 days with each type of cage furniture, thereafter faecal pellets were collected for faecal analyses. The means of activity and means and coefficient of variation for MAP and HR were calculated for days 2, 6, 10 and 14. As a way of determining which of the statistically significant MAP and HR mean changes were biologically meaningful, the night-day differences of the controls on day 14 were used. Both board types lowered MAP of F344 rats; hence dividing walls seem beneficial for F344 welfare. None of the MAP or HR differences in BN rats were biologically significant. No statistically significant differences in faecal corticosterone or IgA excretion were detected. In conclusion, provision of general recommendations with respect to cage furniture for rat cages is complicated because there is a clear genetic component involved in how animals respond to these structures.
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Affiliation(s)
- N Kemppinen
- Laboratory Animal Centre, University of Helsinki, Finland.
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Amini B, Yang PB, Swann AC, Dafny N. DIFFERENTIAL LOCOMOTOR RESPONSES IN MALE RATS FROM THREE STRAINS TO ACUTE METHYLPHENIDATE. Int J Neurosci 2009; 114:1063-84. [PMID: 15370174 DOI: 10.1080/00207450490475526] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Genetic variability is an important consideration in the study of the effect of drugs on humans and animals. Specifically, the effect of drugs on behavior varies from one rat strain to another. Methylphenidate (MPI), commonly known as Ritalin, is a psychostimulant with a pharmacological profile similar to amphetamine and cocaine, and is widely used in the treatment of attention deficit/hyperactivity disorder (ADHD). The purpose of this study was to examine the acute dose-response characteristics of MPD on three different male rat strains: spontaneously hypertensive/hyperactive rats (SHR), Wistar-Kyoto (WKY) rats, and Sprague-Dawley (SD) rats. Results showed clear differences in the pattern of behavioral response to the various MPD doses among the three rat strains. The 0.6 mg/kg MPD dose had no effect on any of the strains. At the dose of 2.5 mg/kg MPD, WKY rats reached peak locomotor activity within the initial 10 min, whereas SHR and SD rats reached peak activity in approximately 30 min. Furthermore, the effects on locomotor activity of SHR were longer in duration and higher in locomotor activity, whereas the effects on SD rats were shorter in duration and amplitude. Following the 10.0 mg/kg MPD, WKY, and SD mats reached their peak locomotor activity within 80 min post-injection, whereas SHR reached their peak locomotor activity within the initial 10 min post-injection. In addition, the SHR strain exhibited increased behavioral sensitivity to MPD as expressed by the latency, duration, and amplitude of their response. In conclusion, the dose-response experiment on the acute effects of MPD demonstrated that there are genetic differences in the responses to MPD.
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Affiliation(s)
- Behrang Amini
- Department of Neurobiology and Anatomy, University of Texas-Medical School at Houston, University of Texas-Graduate School of Biomedical Sciences, Houston, Texas, USA
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Witte K, Lemmer B. Free-running Rhythms in Blood Pressure and Heart Rate in Normotensive and Transgenic Hypertensive Rats. Chronobiol Int 2009. [DOI: 10.3109/07420529509057272] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Rousseau-Ralliard D, Moreau D, Guilland JC, Raederstorff D, Grynberg A. Docosahexaenoic acid, but not eicosapentaenoic acid, lowers ambulatory blood pressure and shortens interval QT in spontaneously hypertensive rats in vivo. Prostaglandins Leukot Essent Fatty Acids 2009; 80:269-77. [PMID: 19428232 DOI: 10.1016/j.plefa.2009.03.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 03/19/2009] [Accepted: 03/20/2009] [Indexed: 11/19/2022]
Abstract
This study was designed to evaluate the effects of individual dietary long-chain n-3 polyunsaturated fatty acids (LCPUFA) on hypertension and cardiac consecutive disorders in spontaneously hypertensive rats (SHR) as compared to Wistar-Kyoto rats (WKY). Rats were fed for 2 months an eicosapentaenoic (EPA)- or docosahexaenoic acid (DHA)-rich diet (240 mg/day) or an n-3 PUFA-free diet. Male SHR (n=6), implanted with cardiovascular telemetry devices, were housed in individual cages for continuous measurements of cardiovascular parameters (blood pressure (BP) and heart rate (HR)) during either activity or rest periods, ECG were recorded during the quiet period. The n-6 PUFA upstream of arachidonic acid was affected in SHR tissues. The cardiac phospholipid fatty acid profile was significantly affected by dietary DHA supply, and EPA in a very lower extent, since DHA only was incorporated in the membranes instead of n-6 PUFAs. Endothelium n-6 PUFA content increased in all SHR groups. Compared to WKY, linoleic acid content decreased in both studied tissues. Cardiac noradrenalin decreased while the adrenal catecholamine stores decreased in SHR as compared to WKY. Both n-3 PUFA supply induced a decrease of adrenal catecholamine stores. Nevertheless after 6 weeks, DHA but not EPA induced a lowering-blood pressure effect and shortened the QT interval in SHR, most probably through its tissue enrichment and a specific effect on adrenergic function. Dietary DHA supply retards blood pressure development and has cardioprotective effect. These findings, showing the cardioprotective effects of DHA in living animals, were obtained in SHR, but may relate to essential hypertension in humans.
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Affiliation(s)
- Delphine Rousseau-Ralliard
- INRA (Institut National de la recherche Agronomique), UMR-A 1154, Laboratoire Lipides Membranaires et Régulation Fonctionnelle du Coeur et des Vaisseaux, Faculté de Pharmacie, Châtenay-Malabry 92290, France.
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28
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Blockade of angiotensin II type-1 receptor increases salt sensitivity in Sprague–Dawley rats. Hypertens Res 2009; 32:513-9. [DOI: 10.1038/hr.2009.40] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lemmer B. Effects of music composed by Mozart and Ligeti on blood pressure and heart rate circadian rhythms in normotensive and hypertensive rats. Chronobiol Int 2009; 25:971-86. [PMID: 19005899 DOI: 10.1080/07420520802539415] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
There is continuing discussion on the effect of music ("Mozart effect") on numerous functions in man and experimental animals. Radiotelemetry now allows one to monitor cardiovascular functions in freely-moving unrestrained experimental animals. Radiotelemetry was used to monitor systolic and diastolic blood pressure (SBP, DBP), heart rate (HR), and motor activity (MA) in male normotensive WKY and hypertensive SHR animals. Rats were synchronized to a 12 h light (L): 12 h dark (D) regimen in an isolated, ventilated, light-controlled, sound-isolated animal container. Music (Mozart, Symphony # 40; Ligeti, String Quartet # 2) were played for 2 h at 75 dB in the animal cabin starting at the onset of L or D in a cross-over design. Data were collected every 5 min for 24 h under control conditions and during and after music. In addition, plasma concentrations of norepinephrine (NE) were determined in unrestrained animals at 3 h intervals over 24 h. In both WKY and SHR, highly significant circadian rhythms were obtained in SBP, DBP, HR, and MA under control conditions; HR was lower and BP higher in SHR than in WKY. NE was circadian rhythmic in both strains with higher values in D; the increase in NE with immobilization was much more pronounced in SHR than in WKY. The music of Mozart had no effect on either parameter in WKY, neither in L nor in D. In contrast, in SHR, the music of Mozart presented in L significantly decreased HR and left BP unaffected, leading to a small decrease in cardiac output. The music of Ligeti significantly increased BP both in L and in D and reflexively reduced HR in L, the effects being long-lasting over 24 h. Interestingly, white noise at 75 dB had no effect at all on either function in both strains. The effects of both Mozart and Ligeti cannot be attributed to a stress reaction, as stress due to cage switch increased HR and BP both in WKY and SHR. The study clearly demonstrates that music of different character (tempo, rhythm, pitch, tonality) can modify cardiovascular functions in freely-moving rats, with SHR being more sensitive than normotensive animals. The relative contribution of the characteristics of the two pieces of music, however, needs further evaluation.
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Affiliation(s)
- Björn Lemmer
- Institut fur Experimentelle und Klinische Pharmakologie und Toxikologie Ruprecht-Karls-Universitat Heidelberg, Mannheim, Germany.
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30
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Hildreth CM, Padley JR, Pilowsky PM, Goodchild AK. Impaired serotonergic regulation of heart rate may underlie reduced baroreflex sensitivity in an animal model of depression. Am J Physiol Heart Circ Physiol 2008; 294:H474-80. [DOI: 10.1152/ajpheart.01009.2007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Serotonin (5-HT) is crucial to normal reflex vagal modulation of heart rate (HR). Reduced baroreflex sensitivity [spontaneous baroreflex sensitivity (sBRS)] and HR variability (HRV) reflect impaired neural, particularly vagal, control of HR and are independently associated with depression. In conscious, telemetered Flinders-Sensitive Line (FSL) rats, a well-validated animal model of depression, we tested the hypothesis that cardiovascular regulatory abnormalities are present and associated with deficient serotonergic control of reflex cardiovagal function. In FSL rats and control Flinders-Resistant (FRL) and Sprague-Dawley (SD) rat strains, diurnal measurements of HR, arterial pressure (AP), activity, sBRS, and HRV were made. All strains had normal and similar diurnal variations in HR, AP, and activity. In FRL rats, HR was elevated, contributing to the reduced HRV and sBRS in this strain. In FSL rats, sBRS and high-frequency power HRV were reduced during the night, indicating reduced reflex cardiovagal activity. The ratio of low- to high-frequency bands of HRV was increased in FSL rats, suggesting a relative predominance of cardiac sympathetic and/or reflex activity compared with FRL and SD rats. These data show that conscious FSL rats have cardiovascular regulatory abnormalities similar to depressed humans. Acute changes in HR, AP, temperature, and sBRS in response to 8-hydroxy-2-(di- n-propylamino)tetralin, a 5-HT1A, 5-HT1B, and 5-HT7 receptor agonist, were also determined. In FSL rats, despite inducing an exaggerated hypothermic effect, 8-hydroxy-2-(di- n-propylamino)tetralin did not decrease HR and AP or improve sBRS, suggesting impaired serotonergic neural control of cardiovagal activity. These data suggest that impaired serotonergic control of cardiac reflex function could be one mechanism linking reduced sBRS to increased cardiac risk in depression.
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Sonalker PA, Jackson EK. Norepinephrine, via beta-adrenoceptors, regulates bumetanide-sensitive cotransporter type 1 expression in thick ascending limb cells. Hypertension 2007; 49:1351-7. [PMID: 17438304 DOI: 10.1161/hypertensionaha.107.088732] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The sympathetic nervous system, via norepinephrine, regulates renal sodium transport, and chronic sympathetic activation causes sustained increases in blood pressure by reducing sodium excretion. Our previous studies show that chronic norepinephrine infusion increases the abundance of the bumetanide-sensitive cotransporter type 1, the apical sodium transporter of the thick ascending limb of Henle's loop. The present study was initiated to elucidate the mechanisms by which norepinephrine regulates the protein levels of this transporter in an immortalized thick ascending limb epithelial cell line. Treatment with norepinephrine, either alone or in the presence of actinomycin D or cycloheximide, had no effect on cotransporter mRNA levels. Treatment with norepinephrine, however, increased bumetanide-sensitive cotransporter type 1 protein levels (70% increase versus control; P=0.012), and pretreatment with cycloheximide blocked the effect of norepinephrine on bumetanide-sensitive cotransporter type 1 protein levels. To further elucidate the mechanism, thick ascending limb cells were treated with norepinephrine in the presence of phentolamine (alpha-adrenoceptor blocker), propranolol (beta-adrenoceptor blocker), SQ22536 (adenylyl cyclase inhibitor), PD098059 (mitogen-activated protein kinase pathway inhibitor), H-89 (protein kinase A inhibitor), or staurosporine (protein kinase C inhibitor). Treatment with propranolol, SQ22536, and H-89 abolished the effects of norepinephrine on bumetanide-sensitive cotransporter type 1 protein levels, whereas staurosporine had no effect. Treatment with PD098059 partially inhibited the effects of norepinephrine (40% decrease versus norepinephrine; P=0.03), and treatment with phentolamine potentiated the effects of norepinephrine (30% increase versus norepinephrine; P=0.02) on bumetanide-sensitive cotransporter type 1 protein levels. We conclude that regulation of bumetanide-sensitive cotransporter type 1 by norepinephrine proceeds via the beta-adrenoceptor receptor-cAMP-protein kinase A pathway that involves in part mitogen-activated protein kinases and that alpha-adrenoceptor activation negatively regulates bumetanide-sensitive cotransporter type 1 protein levels.
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MESH Headings
- 8-Bromo Cyclic Adenosine Monophosphate/pharmacology
- Animals
- Bumetanide/pharmacology
- Cell Line
- Colforsin/pharmacology
- Cyclic AMP/physiology
- Cyclic AMP-Dependent Protein Kinases/drug effects
- Cyclic AMP-Dependent Protein Kinases/physiology
- Gene Expression Regulation/drug effects
- Gene Expression Regulation/physiology
- Loop of Henle/cytology
- Loop of Henle/metabolism
- Mice
- Mice, Transgenic
- Mitogen-Activated Protein Kinases/physiology
- Norepinephrine/physiology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Adrenergic, alpha/drug effects
- Receptors, Adrenergic, alpha/physiology
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/physiology
- Sodium Potassium Chloride Symporter Inhibitors/pharmacology
- Sodium-Potassium-Chloride Symporters/metabolism
- Solute Carrier Family 12, Member 1
- Vasopressins/pharmacology
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Affiliation(s)
- Prajakta A Sonalker
- Department of Pharmacology, Center for Clinical Pharmacology, University of Pittsburgh, School of Medicine, PA 15219, USA
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33
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Hirooka Y. Localized gene transfer and its application for the study of central cardiovascular control. Auton Neurosci 2006; 126-127:120-9. [PMID: 16616703 DOI: 10.1016/j.autneu.2006.02.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 02/22/2006] [Accepted: 02/27/2006] [Indexed: 01/22/2023]
Abstract
The arterial baroreceptor reflex is the major feedback control system that acts to stabilize blood pressure. Abnormalities of this reflex are considered to be an underlying mechanism in the cardiovascular diseases such as hypertension and heart failure. There is accumulating evidence, however, that central nervous system mechanisms are involved in the enhanced sympathetic drive that occurs in these disease states. This article reviews studies performed in our laboratory in which a gene transfer technique, in combination with other methods, was used to determine the functional role of the central control of cardiovascular regulation. We developed a technique to transfer adenovirus vectors encoding specific genes into the nucleus tractus solitarii (NTS) or the rostral ventral medulla (RVLM) of rats in vivo. We applied this technique to hypertensive rats as well as in mice with heart failure to explore the pathophysiological significance of nitric oxide, reactive oxygen species, and Rho-kinase.
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Affiliation(s)
- Yoshitaka Hirooka
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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34
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Abstract
Blood pressure (BP) was analyzed invasively using the telemetry system in unanesthetized, unrestrained healthy adult mongrel cats. After surgical implantation of a telemetry transmitter, BP was transiently elevated due to the invasive nature of the surgery, but it was gradually decreased. BP was largely stabilized seven to ten days postsurgery. Once BP was settled, systolic, diastolic and mean BPs(2) were obtained at 5-min intervals in individual cats. Hourly averages of these BP values revealed a diurnal variation with two peaks at 8:00 and 19:00. We also found that BP was significantly higher when cats were active compared to when they were sleeping or at rest (p<0.05). The average 24-hr BP in 20 healthy cats was 118.4+/-11.0 (systolic), 78.0+/-8.7 (diastolic) and 94.8+/-9.5 mmHg (mean) by the telemetry system.
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Affiliation(s)
- Mika Mishina
- Department of Nephrology and Urology, Veterinary Teaching Hospital, Azabu University, Kanagawa 229-8501, Japan
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35
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Ishiguro T, Iwase M, Kanamaru M, Izumizaki M, Ohshima Y, Homma I. Contribution of Histamine Type-1 Receptor to Metabolic and Behavioral Control of Ventilation. J Physiol Sci 2006; 56:287-95. [PMID: 16875510 DOI: 10.2170/physiolsci.rp006506] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Accepted: 07/30/2006] [Indexed: 11/05/2022]
Abstract
Histaminergic neurons in the hypothalamus are well documented as being involved in the control of autonomic functions, such as the balance of energy metabolism and circadian rhythm. We tested the hypothesis that an activation of the histamine type-1 (H1) receptor is required for the control of ventilation during the course of a day in free-moving mice. Ventilation, aerobic metabolism, and electroencephalogram were measured by a whole-body-plethysmograph, a magnetic-type mass spectrometry system, and a telemetry system, respectively, in H1 receptor-knockout (H1RKO) and wild-type mice. Both genotypes showed daily oscillations in minute ventilation (V(E)) and oxygen consumption (VO(2)), with greater values during the dark period compared to the light period. In the latter, H1RKO mice showed increased V(E) and CO(2) excretion (VCO(2)) relative to wild-type mice, and V(E) was comparable to the VCO(2) increase. However, there was no change in VO(2) in H1RKO mice, suggesting that differences in VCO(2) between genotypes are responsible for differences in V(E) during the light period. During the dark period, VCO(2) was elevated in H1RKO mice compared with WT mice. Because there was no difference in V(E), the ratio of V(E) to VCO(2) was reduced in H1RKO mice. Electroencephalogram results suggested that this might be due to a depressed arousal state in H1RKO mice because the ratio of delta to theta band power spectrum densities was greater in H1RKO mice than in wild-type mice. We concluded that histamine modulates ventilation by affecting metabolism and arousal state via H1 receptors.
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Affiliation(s)
- Takashi Ishiguro
- Department of 2nd Physiology, Showa University School of Medicine, Tokyo, 142-8555, Japan
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36
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Iliescu R, Yanes LL, Bell W, Dwyer T, Baltatu OC, Reckelhoff JF. Role of the renal nerves in blood pressure in male and female SHR. Am J Physiol Regul Integr Comp Physiol 2005; 290:R341-4. [PMID: 16166211 DOI: 10.1152/ajpregu.00035.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Female spontaneously hypertensive rats (SHR) have lower blood pressures than males. The renin-angiotensin system plays an important role in the sexual dimorphism of blood pressure in SHR. The sympathetic nervous system can stimulate renin release, and, therefore, the present study was performed to determine whether the renal sympathetic nerves play a role in the sexual dimorphism of blood pressure in SHR. Male and female SHR underwent bilateral kidney denervation or sham surgery, and, 2 wk later, mean arterial pressure (MAP) and pulse interval were recorded, and baroreflex sensitivity (BRS) was measured by the sequence technique. Left ventricle index (LVI) was also calculated. MAP was higher in sham-operated males than females (182 +/- 5 vs. 169 +/- 4 mmHg; P < 0.01), but, despite the higher MAP in males, LVI was significantly greater in female rats. BRS was not different between sham-operated male and female SHR. Following bilateral renal denervation, MAP was decreased by a similar percentage (8-10%) in males (169 +/- 2 mmHg) and females (152 +/- 3 mmHg), whereas LVI was reduced only in female SHR. BRS was not altered by renal denervation in either sex. These data indicate that renal nerves play a role in the control of blood pressure in SHR independent of sex, but do not play a role in mediating the sex differences in blood pressure.
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Affiliation(s)
- Radu Iliescu
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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37
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Maris ME, Melchert RB, Joseph J, Kennedy RH. Gender differences in blood pressure and heart rate in spontaneously hypertensive and Wistar-Kyoto rats. Clin Exp Pharmacol Physiol 2005; 32:35-9. [PMID: 15730432 DOI: 10.1111/j.1440-1681.2005.04156.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
1. In general, premenopausal women are known to have lower blood pressure than men and animal models have shown a similar sexual dimorphism. However, many studies in animals have been performed using anaesthetized or restrained models. Current experiments were conducted to investigate the relationships among resting heart rate, blood pressure and gender in conscious, unrestrained normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). 2. Biotelemetry transmitters were implanted in 6-month-old animals. Values for heart rate, diastolic blood pressure, systolic blood pressure and pulse pressure were recorded continuously at 10 min intervals after all animals recovered completely from surgery. 3. Normal circadian rhythms in heart rate were found in all rats, with no significant differences among the four groups; the circadian variation in blood pressure was evident in all groups, although much smaller. Heart rate was found to be higher in WKY female rats than in the other three groups. Male WKY rats, male SHR and female SHR had similar heart rates. Male SHR had significantly higher systolic and diastolic blood pressures than female SHR. Male and female WKY rats had similar diastolic blood pressure, but males had slightly higher systolic pressure than females. No significant difference in pulse pressure was found in WKY male and female rats. Male SHR showed significantly higher pulse pressure than female SHR at most times during the day. 4. In conclusion, these results indicate that hypertension is exacerbated in male SHR compared with females under conscious resting conditions and demonstrate that the higher heart rate observed in WKY female rats is not present in the SHR model.
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Affiliation(s)
- M Elizabeth Maris
- Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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38
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Piccione G, Grasso F, Giudice E. Circadian rhythm in the cardiovascular system of domestic animals. Res Vet Sci 2005; 79:155-60. [PMID: 15924933 DOI: 10.1016/j.rvsc.2004.11.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Revised: 09/06/2004] [Accepted: 11/24/2004] [Indexed: 10/25/2022]
Abstract
Definition of the temporal characteristics of cardiovascular rhythms is of scientific interest. This article reviews the literature on the rhythmic pattern of some cardiovascular parameters in domestic animals, providing greater understanding of general chronobiological processes in mammals. The techniques of the chronophysiological studies have been applied in domestic species to determine the existence of periodicity in the cardiovascular functions. Detailed knowledge of these rhythms is useful for clinical, practical and pharmacological purposes and physical performances.
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Affiliation(s)
- G Piccione
- Dipartimento di Morfologia, Biochimica, Fisiologia e Produzioni Animali, Sezione di Fisiologia Veterinaria, Università degli Studi di Messina, Italy.
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Head GA, Lukoshkova EV, Mayorov DN, van den Buuse M. Non-symmetrical double-logistic analysis of 24-h blood pressure recordings in normotensive and hypertensive rats. J Hypertens 2005; 22:2075-85. [PMID: 15480090 DOI: 10.1097/00004872-200411000-00008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine the suitability of a new logistic curve fitting procedure to measure the diurnal rates of transition from the active to the asleep periods separately. METHOD We applied this method to 24-h telemetry recordings of systolic, mean, diastolic arterial pressure (SAP, MAP, DAP, respectively), heart rate (HR) and locomotor activity of normotensive Sprague-Dawley rats (SDR) and spontaneously hypertensive rats (SHR). RESULTS There was a similar pattern of higher awake and lower sleep values (16 +/- 1 mmHg SAP, 77 +/- 2 bpm HR and 40 +/- 2 units activity) in SHR. In SDR, awake-asleep differences were less for SAP (9 +/- 1 mmHg) but similar for HR (83 +/- 2 bpm). In SHR, while the blood pressure patterns were symmetrical, the rate of rise in activity and HR during arousal was more rapid than the rate of decline during the dark to light transition. By contrast in SDR, the arousal rate of increase in blood pressure and HR was much less than the rate of decline. Thus SHR have an exaggerated arousal surge in DAP compared with SDR. Double logistic provides a better fit than Cosinor or square wave and better estimates of day-night differences than partial Fourier. CONCLUSIONS Analysis of 24-h recordings by a new logistic curve method reveals distinct asymmetric circadian patterns of cardiovascular and activity changes in rats. The greater surge in arousal blood pressure in SHR is not associated with differences in HR or activity changes and may be inherent to the underlying mechanisms contributing to the hypertension in SHR.
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Affiliation(s)
- Geoffrey A Head
- Neuropharmacology Laboratory, Baker Heart Research Institute, P.O. Box 6492, St Kilda Rd. Central, Melbourne, Victoria, 8008, Australia.
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40
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El-Mas MM, Abdel-Rahman AA. Longitudinal studies on the effect of hypertension on circadian hemodynamic and autonomic rhythms in telemetered rats. Life Sci 2005; 76:901-15. [PMID: 15589967 DOI: 10.1016/j.lfs.2004.10.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Accepted: 09/23/2004] [Indexed: 11/23/2022]
Abstract
This study dealt with the long-term effects of hypertension on circadian rhythms of hemodynamic and cardiovascular autonomic functions in radiotelemetered rats. Blood pressure (BP), heart rate (HR), spontaneous locomotor activity, and respiration.were monitored in spontaneously hypertensive rats (SHRs), a model of human hypertension, from 14 to 27 weeks of age and in Wistar-Kyoto rats (WKY) as controls. Cardiovascular autonomic changes were determined by time-domain analysis of the variability of BP (standard deviation of mean arterial pressure, SDMAP) and HR (standard deviation of R-R intervals, SDRR, and the root mean square of successive differences in R-R intervals, rMSSD). Compared with WKY rats, the 24-hr MAP and SDMAP were higher at week 14 in SHRs and showed stepwise increases over the study duration, suggesting progressive increases in vasomotor sympathetic activity in hypertensive rats. Also, higher SDRR, rMSSD, and activity and lower HR and respiration were demonstrated in SHRs. Normal circadian rhythms (higher dark-time values) of MAP, HR, SDMAP, and SDRR were evident in WKY rats at week 20 and continued thereafter. Compared with WKY rats, the circadian BP and HR patterns were abolished and inverted, respectively, in SHRs. Lower dark-time, compared with light-time, SDMAP values were observed in SHRs that were associated with temporal increases in HR variability indices. These findings demonstrate that hypertension elicits significant alterations in circadian autonomic and hemodynamic profiles. Further, the steady increases in BP, average level and oscillations, in SHRs may explain the reported progressive age-related vascular and cardiac hypertrophy in these rats.
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Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology, School of Medicine, East Carolina University, Greenville, NC 27858, USA
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van den Buuse M, Wegener N. Involvement of serotonin1A receptors in cardiovascular responses to stress: a radio-telemetry study in four rat strains. Eur J Pharmacol 2005; 507:187-98. [PMID: 15659309 DOI: 10.1016/j.ejphar.2004.11.048] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2004] [Revised: 11/18/2004] [Accepted: 11/23/2004] [Indexed: 11/23/2022]
Abstract
We studied the effect of treatment with the serotonin-1A (5-HT1A) receptor ligands buspirone, 8-hydroxy-di-propyl-aminotetralin (8-OH-DPAT), and (8-[2-(2,3-dihydro-1,4-benzodioxin-2-yl-methylamino)ethyl]-8-azaspiro[4,5]decane-7,9-dione methyl sulphonate (MDL73,005EF) on blood pressure and heart rate increases to open field stress. We compared Spontaneously Hypertensive Rats (SHR), Fawn-Hooded (FH) rats, Wistar-Kyoto (WKY) rats, and Sprague-Dawley (SD) rats instrumented with radio-telemetry probes. Buspirone treatment reduced the blood pressure increase in SHR, FH rats, and WKY rats and heart rate increase in FH rats and WKY rats. 8-OH-DPAT treatment reduced the blood pressure increase in FH rats and WKY rats, but had no effect in SHR and enhanced the pressor response in SD rats. This treatment reduced the heart rate increase in FH rats and WKY rats only. Similarly, MDL73,005EF treatment reduced the blood pressure increase in FH rats and WKY rats, but had no effect in SHR and enhanced this response in SD rats. Little effect of this treatment was seen on heart rate changes. For comparison, diazepam treatment abolished the pressor response in SD rats and reduced it in FH rats and WKY rats, but not SHR. Differential effects of the treatments were also seen between strains for locomotor activity in the open field, although behavioural changes could not explain the effects of the drugs on cardiovascular responses. These data suggest that 5-HT1A receptors are involved in cardiovascular stress responses; however, the extent of this involvement differs between rat strains and the drugs used. These results could be important for our understanding of possible anxiolytic properties of antipsychotic drugs with affinity for the 5-HT1A receptor.
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Affiliation(s)
- Maarten van den Buuse
- Behavioural Neuroscience Laboratory, Mental Health Research Institute, Parkville, VIC, Australia.
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Basset A, Laude D, Laurent S, Elghozi JL. Contrasting circadian rhythms of blood pressure among inbred rat strains: recognition of dipper and non-dipper patterns. J Hypertens 2004; 22:727-37. [PMID: 15126914 DOI: 10.1097/00004872-200404000-00015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The non-dipper pattern, i.e. the lack of nocturnal blood pressure (BP) fall, carries a high risk of cardiovascular complications, both in hypertensive and normotensive subjects. Without genetic engineering, experimental demonstration of the non-dipper phenomenon is lacking. The purpose of this study was to assess the haemodynamic and behavioural daily parameters among various strains of rats - spontaneously hypertensive rats (SHR), Wistar-Kyoto (WKY) and Fischer 344 (F344) - in order to characterize their circadian patterns and to detect a non-dipper animal model. METHODS Changes in BP, heart rate (HR), and spontaneous locomotor activity (SLA) were recorded continuously for 11 days using telemetry in freely moving 10-week-old male SHR, WKY and F344 rats, in standardized laboratory conditions. Variations in haemodynamic and behavioural parameters were assessed in terms of day/night differences and spectral power corresponding with the 24-h period. RESULTS All rats exhibited clear circadian variations in HR and in SLA, in synchrony with the light cycle. Light/dark differences in BP were significantly lower in F344 compared with those of SHR and WKY. The smaller circadian changes in BP observed in F344 were also demonstrated using spectral analysis: the peak detected at 24-h was reduced in F344 compared with SHR and WKY. CONCLUSION The inbred F344 strain lacks the typical circadian BP rhythm while oscillations of HR and SLA are maintained, suggesting different regulatory mechanisms. The F344 strain may represent a useful animal model for studying the effects of drugs aimed at restoring the dipper status.
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Affiliation(s)
- Alexandra Basset
- INSERM EMI 0107, Laboratoire de Biomécanique et Pharmacologie de la Paroi Artérielle, Paris, France.
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Mortola JP, Lanthier C. Scaling the amplitudes of the circadian pattern of resting oxygen consumption, body temperature and heart rate in mammals. Comp Biochem Physiol A Mol Integr Physiol 2004; 139:83-95. [PMID: 15471685 DOI: 10.1016/j.cbpb.2004.07.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Revised: 07/01/2004] [Accepted: 07/12/2004] [Indexed: 11/25/2022]
Abstract
We questioned whether the amplitudes of the circadian pattern of body temperature (T(b)), oxygen consumption (V (O(2))) and heart rate (HR) changed systematically among species of different body weight (W). Because bodies of large mass have a greater heat capacitance than those of smaller mass, if the relative amplitude (i.e., amplitude/mean value) of metabolic rate was constant, one would expect the T(b) oscillation to decrease with the increase in the species W. We compiled data of T(b), V (O(2)) and HR from a literature survey of over 200 studies that investigated the circadian pattern of these parameters. Monotremata, Marsupials and Chiroptera, were excluded because of their characteristically low metabolic rate and T(b). The peak-trough ratios of V (O(2)) (42 species) and HR (35 species) averaged, respectively, 1.57+/-0.08, and 1.35+/-0.07, and were independent of W. The daily high values of T(b) did not change, while the daily low T(b) values slightly increased, with the species W; hence, the high-low T(b) difference (57 species) decreased with W (3.3 degrees C.W(-0.13)). However, the decrease in T(b) amplitude with W was much less than expected from physical principles, and the high-low T(b) ratio remained significantly above unity even in the largest mammals. Thus, it appears that in mammals, despite the huge differences in physical characteristics, the amplitude of the circadian pattern is a fixed (for V (O(2)) and HR), or almost fixed (for T(b)), fraction of the 24-h mean value. Presumably, the amplitudes of the oscillations are controlled parameters of physiological significance.
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Affiliation(s)
- Jacopo P Mortola
- Department of Physiology, McGill University, 3655, Sir William Osler Promenade Montreal, Quebec, Canada, H3G 1Y6.
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Abstract
OBJECTIVE The objectives were two-fold: (1) determine whether the use of hydralazine as antihypertensive therapy during obesity development exacerbated obesity-related cardioacceleration and hormonal abnormalities; (2) determine whether the absence of hypertension in obesity attenuated obesity-related abnormalities in hemodynamics, cardiac hypertrophy, and hormonal profile. DESIGN Female New Zealand White rabbits were divided into lean control (n=12), lean hydralazine-treated (n=9), obese control (n=11), and obese hydralazine-treated (n=8) groups. Pretreatment mean blood pressure (BP) and heart rate (HR) were determined using telemetry. Pretreatment BP was maintained during 12 weeks of obesity development using hydralazine. MEASUREMENTS Chronically measured BP and HR; plasma/blood volume; wet and dry ventricular weights; body fat/water; and hormonal profile (plasma renin activity, aldosterone, cortisol, atrial natriuretic peptide, adrenaline, and noradrenaline). RESULTS Hydralazine treatment in obese animals attenuated obesity-related renin-angiotensin system (RAS) activation. In contrast, RAS was activated in lean hydralazine, as indicated by increased plasma aldosterone. The absence of hypertension in obese hydralazine did not result in attenuation of cardioacceleration, cardiac hypertrophy, or intravascular volumes. CONCLUSIONS Hydralazine treatment in obese rabbits did not exacerbate obesity-related cardiovascular and hormonal alterations. Cardioacceleration and cardiac hypertrophy persisted in obese hydralazine despite BP control, suggesting hypertension-independent effects of obesity on these variables. Hydralazine's effects on RAS activation differed in lean and obese rabbits, suggesting that the systemic effects of hydralazine as a control therapy in evaluation of antihypertensive medications may differ depending on the underlying pathology.
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Affiliation(s)
- J F Carroll
- Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
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Hirooka Y. Adenovirus-mediated gene transfer into the brain stem to examine cardiovascular function: role of nitric oxide and Rho-kinase. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2004; 84:233-49. [PMID: 14769438 DOI: 10.1016/j.pbiomolbio.2003.11.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The central nervous system plays an important role in the regulation of blood pressure via the sympathetic nervous system. Abnormal regulation of the sympathetic nerve activity is involved in the pathophysiology of hypertension. In particular, the brain stem, including the nucleus tractus solitarii (NTS) and the rostral ventrolateral medulla (RVLM), is a key site that controls and maintains blood pressure via the sympathetic nervous system. Nitric oxide (NO) is a unique molecule that influences sympathetic nerve activity. Rho-kinase is a downstream effector of the small GTPase, Rho, and is implicated in various cellular functions. We developed a technique to transfer adenovirus vectors encoding endothelial nitric oxide synthase and dominant-negative Rho-kinase into the NTS or the RVLM of rats in vivo. We applied this technique to hypertensive rats to explore the physiological significance of NO and Rho-kinase.
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Affiliation(s)
- Yoshitaka Hirooka
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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Naito Y, Tsujino T, Kawasaki D, Okumura T, Morimoto S, Masai M, Sakoda T, Fujioka Y, Ohyanagi M, Iwasaki T. Circadian gene expression of clock genes and plasminogen activator inhibitor-1 in heart and aorta of spontaneously hypertensive and Wistar-Kyoto rats. J Hypertens 2003; 21:1107-15. [PMID: 12777947 DOI: 10.1097/00004872-200306000-00010] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Heart and aorta possess biologic clocks, but their involvement in genetic hypertension has been unknown. Plasminogen activator inhibitor-1 (PAI-1) expression is directly regulated by clock genes, while angiotensin II modulates both PAI-1 and clock gene expression. We therefore examined circadian expression of PAI-1 and clock genes, and effects of angiotensin type 1 (AT1) receptor antagonism, in heart and aorta of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. METHODS We examined cardiac and aortic mRNA expression for PAI-1 and clock genes (Per2, Bmal1, Clock, and Dbp) every 4 h throughout the day by quantitative reverse transcription-polymerase chain reaction, and intervention with the AT1 receptor antagonist candesartan and equihypotensive hydralazine. RESULTS Cardiac PAI-1 expression was high in the dark, while aortic PAI-1 expression was high in the light. Both cardiac and aortic PAI-1 expression were greater in SHR than in WKY rats. Candesartan treatment decreased cardiac PAI-1 expression only in the dark in WKY rats but throughout the day in SHR. Candesartan but not hydralazine strongly attenuated circadian fluctuation of aortic PAI-1 mRNA in SHR and WKY rats. Clock genes oscillated synchronously in heart and aorta of SHR and WKY rats. Clock gene expression was increased in heart but not aorta of SHR. Candesartan did not affect clock gene expression. CONCLUSIONS Enhanced expression of clock genes may increase PAI-1 expression in concert with activated renin-angiotensin system in SHR heart. Rather than clock genes, the renin-angiotensin system induces daily fluctuation and increased expression of aortic PAI-1 mRNA in SHR.
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Affiliation(s)
- Yoshiro Naito
- Department of Internal Medicine, Cardiovascular Division, Hyogo College of Medicine, Nishinomiya, Japan
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Ferguson SA, Cada AM. A longitudinal study of short- and long-term activity levels in male and female spontaneously hypertensive, Wistar-Kyoto, and Sprague-Dawley rats. Behav Neurosci 2003; 117:271-82. [PMID: 12708524 DOI: 10.1037/0735-7044.117.2.271] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The pattern of locomotor activity across development was assessed in male and female spontaneously hypertensive (SHR), Wistar-Kyoto (WKY), and Sprague-Dawley (SD) rats. Open field activity did not indicate hyperactivity in the SHR. Instead, the SD strain was generally more active. Strains and sexes did not differ in open-field locomotor response to drug challenges. When short-term (10-12 min) activity in different apparatuses was compared, the SD were most active in the open field, the SHR in the residential figure-eight maze, and the WKY in the running wheel. Long-term tests indicated hyperactivity in the SHR in the residential figure-eight maze and hypoactivity in the SD in the running wheels. Until such strain differences in activity are thoroughly defined, the use of the SHR as a model of attention-deficit/ hyperactivity disorder is limited.
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Affiliation(s)
- Sherry A Ferguson
- Division of Neurotoxicology, Jefferson, National Center for Toxicological Research, U.S. Food and Drug Administration, Arkansas 72079, USA.
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Abstract
The effect of acute treatment with clozapine, risperidone and haloperidol on cardiovascular response to open field novelty stress was investigated in rats using radio-telemetry and video-tracking analysis. Pretreatment with clozapine dose-dependently inhibited the pressor response, tachycardia and increase in dP/dt and caused a marked reduction of exploratory locomotor activity. Similar effects were observed after risperidone treatment. Haloperidol treatment markedly reduced locomotor activity but its cardiovascular effects were limited to a more rapid return of heart rate towards baseline levels. These data suggest that particularly the atypical antipsychotic drugs, clozapine and risperidone, but not the typical antipsychotic, haloperidol, reduce cardiovascular stress responses, an effect that could reflect their anxiolytic action. Such anxiolytic effects could contribute to the beneficial clinical effects of atypical antipsychotic drugs in patients with schizophrenia.
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Affiliation(s)
- Maarten van den Buuse
- Behavioural Neuroscience Laboratory, Mental Health Research Institute of Victoria, Parkville, Victoria 3052, Australia.
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Abstract
AbstractVarious tools have been developed over previous years to study the welfare of laboratory animals. These include preference tests, which are commonly used to evaluate housing environments. Preference tests, however, have some pitfalls: they supply information only on the animals’ present preferences, and they allow the animal the choice only between the options offered. Other methods based upon the collection of clinico-chemical data require handling of the animals, which can be stressful in itself. An alternative may be to use telemetry to measure the changes in physiological parameters caused by different environmental conditions. The aim of this study was to use telemetry to evaluate the short-term impact of housing conditions on rodents. We monitored heart rate, blood pressure and body temperature in rats kept on three different types of flooring — bedding, grid floors and plastic floors. The study revealed significant differences in systolic and diastolic blood pressure, heart rate and body temperature between rats housed in the three conditions, indicating that both grid floors and plastic floors are more stressful for the animals than bedding. The observed differences did not diminish over the two-week observation period. The grid-floor housing induced elevations in blood pressure and heart rate. Blood pressure remained elevated even when the animals were returned to standard bedding, whereas the heart rate declined back to its original value immediately in response to this shift. This study shows that telemetry is a very effective tool but that it needs integrating with other methods: in addition, a greater understanding of the biological significance of the changes in cardiovascular parameters is required before the hypothesis that these changes represent an indication of distress can be accepted.
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