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Ma J, Yanase S, Udagawa L, Kuwaki T, Kusumoto-Yoshida I. Activation of neurons in the insular cortex and lateral hypothalamus during food anticipatory period caused by food restriction in mice. J Physiol Sci 2023; 73:34. [PMID: 38066417 PMCID: PMC10717706 DOI: 10.1186/s12576-023-00892-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 11/24/2023] [Indexed: 12/18/2023]
Abstract
Mice fed a single meal daily at a fixed time display food anticipatory activity (FAA). It has been reported that the insular cortex (IC) plays an essential role in food anticipation, and lateral hypothalamus (LH) regulates the expression of FAA. However, how these areas contribute to FAA production is still unclear. Thus, we examined the temporal and spatial activation pattern of neurons in the IC and LH during the food anticipation period to determine their role in FAA establishment. We observed an increase of c-Fos-positive neurons in the IC and LH, including orexin neurons of male adult C57BL/6 mice. These neurons were gradually activated from the 1st day to 15th day of restricted feeding. The activation of these brain regions, however, peaked at a distinct point in the food restriction procedure. These results suggest that the IC and LH are differently involved in the neural network for FAA production.
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Affiliation(s)
- Jihao Ma
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Sakurako Yanase
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Lisa Udagawa
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Tomoyuki Kuwaki
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan
| | - Ikue Kusumoto-Yoshida
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, 890-8544, Japan.
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2
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Core body temperature varies according to the time of exercise without affecting orexin-A production in the dorsolateral hypothalamus in rat. J Therm Biol 2023. [DOI: 10.1016/j.jtherbio.2023.103522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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3
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YAMANAKA R, YUNOKI T, ARIMITSU T, YANO T. Effect of manipulation of fatigue sense on ventilatory response during recovery after intense exercise. GAZZETTA MEDICA ITALIANA ARCHIVIO PER LE SCIENZE MEDICHE 2022. [DOI: 10.23736/s0393-3660.20.04444-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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4
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Sobczak F, Pais-Roldán P, Takahashi K, Yu X. Decoding the brain state-dependent relationship between pupil dynamics and resting state fMRI signal fluctuation. eLife 2021; 10:e68980. [PMID: 34463612 PMCID: PMC8460262 DOI: 10.7554/elife.68980] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 08/27/2021] [Indexed: 01/19/2023] Open
Abstract
Pupil dynamics serve as a physiological indicator of cognitive processes and arousal states of the brain across a diverse range of behavioral experiments. Pupil diameter changes reflect brain state fluctuations driven by neuromodulatory systems. Resting-state fMRI (rs-fMRI) has been used to identify global patterns of neuronal correlation with pupil diameter changes; however, the linkage between distinct brain state-dependent activation patterns of neuromodulatory nuclei with pupil dynamics remains to be explored. Here, we identified four clusters of trials with unique activity patterns related to pupil diameter changes in anesthetized rat brains. Going beyond the typical rs-fMRI correlation analysis with pupil dynamics, we decomposed spatiotemporal patterns of rs-fMRI with principal component analysis (PCA) and characterized the cluster-specific pupil-fMRI relationships by optimizing the PCA component weighting via decoding methods. This work shows that pupil dynamics are tightly coupled with different neuromodulatory centers in different trials, presenting a novel PCA-based decoding method to study the brain state-dependent pupil-fMRI relationship.
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Affiliation(s)
- Filip Sobczak
- Translational Neuroimaging and Neural Control Group, High Field Magnetic Resonance Department, Max Planck Institute for Biological CyberneticsTübingenGermany
- Graduate Training Centre of Neuroscience, International Max Planck Research School, University of TuebingenTuebingenGermany
| | - Patricia Pais-Roldán
- Translational Neuroimaging and Neural Control Group, High Field Magnetic Resonance Department, Max Planck Institute for Biological CyberneticsTübingenGermany
- Institute of Neuroscience and Medicine 4, Medical Imaging Physics, Forschungszentrum JülichJülichGermany
| | - Kengo Takahashi
- Translational Neuroimaging and Neural Control Group, High Field Magnetic Resonance Department, Max Planck Institute for Biological CyberneticsTübingenGermany
- Graduate Training Centre of Neuroscience, International Max Planck Research School, University of TuebingenTuebingenGermany
| | - Xin Yu
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical SchoolCharlestown, MassachusettsUnited States
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Lamotte G, Shouman K, Benarroch EE. Stress and central autonomic network. Auton Neurosci 2021; 235:102870. [PMID: 34461325 DOI: 10.1016/j.autneu.2021.102870] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 07/09/2021] [Accepted: 08/19/2021] [Indexed: 12/26/2022]
Abstract
The central autonomic network (CAN) plays a critical role in the stress response, which is triggered by challenges on the homeostasis (physiological stressors) or unpleasant social or environmental situations. This review focuses on the role of areas of the CAN including the insular and anterior cingulate cortices, extended amygdala, hypothalamus, periaqueductal gray and locus coeruleus in the stress response. These areas are interconnected and affect sympathetic or parasympathetic output via their influence on premotor or preganglionic autonomic neurons in the lower brainstem and spinal cord. The insula integrates multiple inputs to create a sense of the physiological state of the body, whereas the anterior cingulate initiates predictive visceromotor commands. The amygdala and bed nucleus of the stria terminalis provide automatic emotional tagging and trigger automatic survival responses to threat via their outputs to the hypothalamus, periaqueductal gray, and lower brainstem. Several regions of the hypothalamus, including the paraventricular nucleus, dorsomedial nucleus and lateral hypothalamic area participate in different patterns of stress response according to the type of stimulus and projections to premotor and preganglionic autonomic neurons. The periaqueductal gray initiates different patterns of autonomic, pain modulatory, and motor responses, including the "fight or flight" or "playing dead" responses. The locus coeruleus promotes emotional learning in the amygdala associated with states of anxiety. Neurons of the C1 area of the rostral ventrolateral medulla elicit sympathoexcitatory responses to internal stressors such as hypoxia and inflammation. The ventromedial medulla, including the nucleus raphe pallidus, initiates sympathoexcitatory responses to social and other external stressors.
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Affiliation(s)
- Guillaume Lamotte
- Mayo Clinic, Department of Neurology, Rochester, MN, USA; University of Utah, Department of Neurology, Salt Lake City, UT, USA.
| | - Kamal Shouman
- Mayo Clinic, Department of Neurology, Rochester, MN, USA
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6
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Olsen N, Furlong TM, Carrive P. Behavioural and cardiovascular effects of orexin-A infused into the central amygdala under basal and fear conditions in rats. Behav Brain Res 2021; 415:113515. [PMID: 34371088 DOI: 10.1016/j.bbr.2021.113515] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 07/16/2021] [Accepted: 08/03/2021] [Indexed: 10/20/2022]
Abstract
The neuropeptide orexin-A (OX-A) has diverse functions, including maintaining arousal, autonomic control, motor activity and stress responses. These functions are regulated at different terminal regions where OX-A is released. The current study examined the physiological and behavioural effects of OX-A microinjections into the central amygdala (CeA) under basal and stressed conditions in rats. When OX-A was microinjected into the CeA and the animals returned to the home-cage, heart rate and mean arterial pressure were increased compared to vehicle-injected controls. General activity of the animal was also increased, indicating that OX-A activity in CeA contributes to increased arousal. This outcome is similar to the effects of central intracerebroventricular infusions of OX-A, as well as the cardiovascular effects previously demonstrated at many of OX's efferent hypothalamic and brainstem structures. In a second study, animals were fear-conditioned to a context by delivery of electric footshocks and then animals were re-exposed to the conditioned context at test. When OX-A was microinjected at test, freezing behaviour was reduced and there was a corresponding increase in the animal's activity but no impact on the pressor and cardiac responses (i.e, blood pressure and heart rate were unchanged). This reduction in freezing suggests that OX-A activates amygdala neurons that inhibit freezing, which is similar to the actions of other neuropeptides in the CeA that modulate the appropriate defence response to fearful stimuli. Overall, these data indicate that the CeA is an important site of OX-A modulation of cardiovascular and motor activity, as well as conditioned freezing responses.
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Affiliation(s)
- Nick Olsen
- School of Medical Sciences, The University of New South Wales, Sydney, Australia
| | - Teri M Furlong
- School of Medical Sciences, The University of New South Wales, Sydney, Australia; Neuroscience Research Australia, Randwick, Australia.
| | - Pascal Carrive
- School of Medical Sciences, The University of New South Wales, Sydney, Australia
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7
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Kuwaki T. Orexin (hypocretin) participates in central autonomic regulation during fight-or-flight response. Peptides 2021; 139:170530. [PMID: 33741478 DOI: 10.1016/j.peptides.2021.170530] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 03/12/2021] [Accepted: 03/12/2021] [Indexed: 12/25/2022]
Abstract
Our daily life does not only involve a calm resting state but is rather full of perturbations that induce active states such as moving, eating, and communicating. During such active conditions, cardiorespiratory regulation should be adjusted according to bodily demand, which differs from that during the resting state, by modulating or resetting the operating point. To explore neural mechanisms in the state-dependent adjustment of central autonomic regulation, my research group has recently focused on the fight-or-flight response because the stressor induces not only cognitive, emotional, and behavioral changes but also autonomic changes. In this brief review, I will summarize our discovery using orexin knockout mice and orexin neuron-ablated mice for the possible contribution of orexin, a hypothalamic neuropeptide, to the state-dependent adjustment of the central autonomic regulation. In addition, I will introduce some recent discovery using optogenetic manipulation of the orexin and related systems. The diversity of synaptic control of the cardiovascular and respiratory neurons appears necessary for animals to adapt themselves to ever-changing life circumstances and behavioral states. The orexin system is likely to function as one of the essential modulators for coordinating the circuits controlling autonomic functions and behaviors.
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Affiliation(s)
- Tomoyuki Kuwaki
- Department of Physiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Sakuragaoka 8-35-1, Kagoshima, 890-8544, Japan.
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8
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Casagrande M, Favieri F, Langher V, Guarino A, Di Pace E, Germanò G, Forte G. The Night Side of Blood Pressure: Nocturnal Blood Pressure Dipping and Emotional (dys)Regulation. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17238892. [PMID: 33265925 PMCID: PMC7729863 DOI: 10.3390/ijerph17238892] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 11/22/2020] [Accepted: 11/27/2020] [Indexed: 12/15/2022]
Abstract
Introduction: The dipping phenomenon is a physiological drop in blood pressure (around 10-20%) during sleep and represents an event related to the circadian blood pressure trend. This phenomenon, in some cases, is characterized by some alterations that can be expressed by an increase (extreme dipping), a decrease (non-dipping), or a reverse (i.e., higher blood pressure during sleep compared to awake state; reverse-dipping) physiological decline of blood pressure. Few studies focused on the association between the circadian variation of blood pressure and psychological variables, although this information could help understanding how psychological characteristics (e.g., emotional regulation or dysregulation) interact with individuals' physiological processes. Given the association between emotional dysregulation and essential hypertension, this study aimed to investigate the relationship between alexithymia and dipping status in a sample of healthy and hypertensive adults in the absence of other medical conditions. Methods: Two hundred and ten adults took part in the study and were classified, according to ambulatorial blood pressure measure (ABPM), into three groups: dippers (n = 70), non-dippers (n = 70), and extreme dippers (n = 70). The participants completed a socio-demographic and anamnestic interview and the Toronto Alexithymia Scale-20 (TAS-20). Results: The ANOVAs on the TAS-20 subscales showed that the groups differed in the difficulty identifying feelings and difficulty describing feelings. In both the subscales, dippers showed lower scores than non-dippers and extreme dippers. The ANOVA on the global score of TAS-20 confirmed that dippers were less alexithymic than both extreme dippers and non-dippers. Conclusions: This study confirms that some psychological factors, like alexithymia, could represent a characteristic of patients who fail to exhibit an adaptive dipping phenomenon. Moreover, an association between an excessive reduction of BP (extreme dipping) or a lack of the decrease of BP during sleep (non-dipping) and a worse emotional regulation, considering alexithymia construct, was highlighted for the first time, confirming the relevant role of the emotional process in the modulation of an essential psychophysiological process such as the circadian variation of BP.
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Affiliation(s)
- Maria Casagrande
- Dipartimento di Psicologia Dinamica e Clinica, Università di Roma “Sapienza”, 00185 Roma, Italy;
- Correspondence:
| | - Francesca Favieri
- Dipartimento di Psicologia, Università di Roma “Sapienza”, 00185 Roma, Italy; (F.F.); (A.G.); (E.D.P.); (G.F.)
| | - Viviana Langher
- Dipartimento di Psicologia Dinamica e Clinica, Università di Roma “Sapienza”, 00185 Roma, Italy;
| | - Angela Guarino
- Dipartimento di Psicologia, Università di Roma “Sapienza”, 00185 Roma, Italy; (F.F.); (A.G.); (E.D.P.); (G.F.)
| | - Enrico Di Pace
- Dipartimento di Psicologia, Università di Roma “Sapienza”, 00185 Roma, Italy; (F.F.); (A.G.); (E.D.P.); (G.F.)
| | - Giuseppe Germanò
- Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche e Geriatriche, Università di Roma “Sapienza”, 00815 Roma, Italy;
| | - Giuseppe Forte
- Dipartimento di Psicologia, Università di Roma “Sapienza”, 00185 Roma, Italy; (F.F.); (A.G.); (E.D.P.); (G.F.)
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9
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Guyenet PG, Stornetta RL, Souza GMPR, Abbott SBG, Brooks VL. Neuronal Networks in Hypertension: Recent Advances. Hypertension 2020; 76:300-311. [PMID: 32594802 DOI: 10.1161/hypertensionaha.120.14521] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurogenic hypertension is associated with excessive sympathetic nerve activity to the kidneys and portions of the cardiovascular system. Here we examine the brain regions that cause heightened sympathetic nerve activity in animal models of neurogenic hypertension, and we discuss the triggers responsible for the changes in neuronal activity within these regions. We highlight the limitations of the evidence and, whenever possible, we briefly address the pertinence of the findings to human hypertension. The arterial baroreflex reduces arterial blood pressure variability and contributes to the arterial blood pressure set point. This set point can also be elevated by a newly described cerebral blood flow-dependent and astrocyte-mediated sympathetic reflex. Both reflexes converge on the presympathetic neurons of the rostral medulla oblongata, and both are plausible causes of neurogenic hypertension. Sensory afferent dysfunction (reduced baroreceptor activity, increased renal, or carotid body afferent) contributes to many forms of neurogenic hypertension. Neurogenic hypertension can also result from activation of brain nuclei or sensory afferents by excess circulating hormones (leptin, insulin, Ang II [angiotensin II]) or sodium. Leptin raises blood vessel sympathetic nerve activity by activating the carotid bodies and subsets of arcuate neurons. Ang II works in the lamina terminalis and probably throughout the brain stem and hypothalamus. Sodium is sensed primarily in the lamina terminalis. Regardless of its cause, the excess sympathetic nerve activity is mediated to some extent by activation of presympathetic neurons located in the rostral ventrolateral medulla or the paraventricular nucleus of the hypothalamus. Increased activity of the orexinergic neurons also contributes to hypertension in selected models.
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Affiliation(s)
- Patrice G Guyenet
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - Ruth L Stornetta
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - George M P R Souza
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - Stephen B G Abbott
- From the Department of Pharmacology, University of Virginia, Charlottesville (P.G.G., R.L.S., G.M.P.R.S., S.B.G.A.)
| | - Virginia L Brooks
- Department of Chemical Physiology and Biochemistry, Oregon Health & Sciences University, Portland (V.L.B.)
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10
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Barnett S, Li A. Orexin in Respiratory and Autonomic Regulation, Health and Diseases. Compr Physiol 2020; 10:345-363. [DOI: 10.1002/cphy.c190013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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11
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Benarroch EE. Control of the cardiovascular and respiratory systems during sleep. Auton Neurosci 2019; 218:54-63. [DOI: 10.1016/j.autneu.2019.01.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 01/28/2019] [Accepted: 01/28/2019] [Indexed: 01/01/2023]
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12
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Benarroch EE. Brainstem integration of arousal, sleep, cardiovascular, and respiratory control. Neurology 2018; 91:958-966. [PMID: 30355703 DOI: 10.1212/wnl.0000000000006537] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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13
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Dampney RAL. Central neural control of the cardiovascular system: current perspectives. ADVANCES IN PHYSIOLOGY EDUCATION 2016; 40:283-296. [PMID: 27445275 DOI: 10.1152/advan.00027.2016] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 05/23/2016] [Indexed: 06/06/2023]
Abstract
This brief review, which is based on a lecture presented at the American Physiological Society Teaching Refresher Course on the Brain and Systems Control as part of the Experimental Biology meeting in 2015, aims to summarize current concepts of the principal mechanisms in the brain that regulate the autonomic outflow to the cardiovascular system. Such cardiovascular regulatory mechanisms do not operate in isolation but are closely coordinated with respiratory and other regulatory mechanisms to maintain homeostasis. The brain regulates the cardiovascular system by two general means: 1) feedforward regulation, often referred to as "central command," and 2) feedback or reflex regulation. In most situations (e.g., during exercise, defensive behavior, sleep, etc.), both of these general mechanisms contribute to overall cardiovascular homeostasis. The review first describes the mechanisms and central circuitry subserving the baroreceptor, chemoreceptor, and other reflexes that work together to regulate an appropriate level of blood pressure and blood oxygenation and then considers the brain mechanisms that defend the body against more complex environmental challenges, using dehydration and cold and heat stress as examples. The last section of the review considers the central mechanisms regulating cardiovascular function associated with different behaviors, with a specific focus on defensive behavior and exercise.
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Affiliation(s)
- Roger A L Dampney
- School of Medical Sciences (Physiology) and Bosch Institute, The University of Sydney, Sydney, New South Wales, Australia
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14
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Kanbar R, Stornetta RL, Guyenet PG. Sciatic nerve stimulation activates the retrotrapezoid nucleus in anesthetized rats. J Neurophysiol 2016; 116:2081-2092. [PMID: 27512023 DOI: 10.1152/jn.00543.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 08/03/2016] [Indexed: 11/22/2022] Open
Abstract
Retrotrapezoid nucleus (RTN) neurons sustain breathing automaticity. These neurons have chemoreceptor properties, but their firing is also regulated by multiple synaptic inputs of uncertain function. Here we test whether RTN neurons, like neighboring presympathetic neurons, are excited by somatic afferent stimulation. Experiments were performed in Inactin-anesthetized, bilaterally vagotomized, paralyzed, mechanically ventilated Sprague-Dawley rats. End-expiratory CO2 (eeCO2) was varied between 4% and 10% to modify rate and amplitude of phrenic nerve discharge (PND). RTN and presympathetic neurons were recorded extracellularly below the facial motor nucleus with established criteria. Sciatic nerve stimulation (SNstim, 1 ms, 0.5 Hz) slightly increased blood pressure (6.6 ± 1.6 mmHg) and heart rate and, at low eeCO2 (<5.5%), entrained PND. Ipsi- and contralateral SNstim produced the known biphasic activation of presympathetic neurons. SNstim evoked a similar but weaker biphasic response in up to 67% of RTN neurons and monophasic excitation in the rest. At low eeCO2, RTN neurons were silent and responded more weakly to SNstim than at high eeCO2 RTN neuron firing was respiratory modulated to various degrees. The phasic activation of RTN neurons elicited by SNstim was virtually unchanged at high eeCO2 when PND entrainment to the stimulus was disrupted. Thus RTN neuron response to SNstim did not result from entrainment to the central pattern generator. Overall, SNstim shifted the relationship between RTN firing and eeCO2 upward. In conclusion, somatic afferent stimulation increases RTN neuron firing probability without altering their response to CO2. This pathway may contribute to the hyperpnea triggered by nociception, exercise (muscle metabotropic reflex), or hyperthermia.
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Affiliation(s)
- Roy Kanbar
- Department of Pharmaceutical Sciences, School of Pharmacy, Lebanese American University, Byblos, Lebanon; and
| | - Ruth L Stornetta
- Department of Pharmacology, School of Medicine, University of Virginia, Charlottesville, Virginia
| | - Patrice G Guyenet
- Department of Pharmacology, School of Medicine, University of Virginia, Charlottesville, Virginia
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15
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Dampney RAL. Central mechanisms regulating coordinated cardiovascular and respiratory function during stress and arousal. Am J Physiol Regul Integr Comp Physiol 2015; 309:R429-43. [DOI: 10.1152/ajpregu.00051.2015] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/28/2015] [Indexed: 02/07/2023]
Abstract
Actual or potentially threatening stimuli in the external environment (i.e., psychological stressors) trigger highly coordinated defensive behavioral responses that are accompanied by appropriate autonomic and respiratory changes. As discussed in this review, several brain regions and pathways have major roles in subserving the cardiovascular and respiratory responses to threatening stimuli, which may vary from relatively mild acute arousing stimuli to more prolonged life-threatening stimuli. One key region is the dorsomedial hypothalamus, which receives inputs from the cortex, amygdala, and other forebrain regions and which is critical for generating autonomic, respiratory, and neuroendocrine responses to psychological stressors. Recent studies suggest that the dorsomedial hypothalamus also receives an input from the dorsolateral column in the midbrain periaqueductal gray, which is another key region involved in the integration of stress-evoked cardiorespiratory responses. In addition, it has recently been shown that neurons in the midbrain colliculi can generate highly synchronized autonomic, respiratory, and somatomotor responses to visual, auditory, and somatosensory inputs. These collicular neurons may be part of a subcortical defense system that also includes the basal ganglia and which is well adapted to responding to threats that require an immediate stereotyped response that does not involve the cortex. The basal ganglia/colliculi system is phylogenetically ancient. In contrast, the defense system that includes the dorsomedial hypothalamus and cortex evolved at a later time, and appears to be better adapted to generating appropriate responses to more sustained threatening stimuli that involve cognitive appraisal.
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Affiliation(s)
- Roger A. L. Dampney
- School of Medical Sciences (Physiology) and Bosch Institute, University of Sydney, New South Wales, Australia
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16
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Kuwaki T. Thermoregulation under pressure: a role for orexin neurons. Temperature (Austin) 2015; 2:379-91. [PMID: 27227052 PMCID: PMC4843912 DOI: 10.1080/23328940.2015.1066921] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 06/20/2015] [Accepted: 06/22/2015] [Indexed: 01/06/2023] Open
Abstract
In the past, studies on stress responses and sleep/wake regulation were performed separately. The discovery of orexin (hypocretin) in 1998, however, dramatically changed the course of research and new findings regarding its role in these complex processes provided a better insight into their interactions and intricacies. Orexin-containing neuronal activity has been found to be minimal during sleep. It increases during the waking period and further increases during the active waking period, which includes stress responses and exploratory behaviors. Autonomic regulation of the body, which includes body temperature, blood flow, and ventilation, is also activated along with the change in vigilance states. Our recent findings suggest that orexin neurons act as a conductor of orchestration for vigilance states, behaviors, and autonomic functions. Body temperature regulation by orexin neurons seems to be mediated by one of its cotransmitters while cardiovascular and respiratory regulation are mediated by orexin itself.
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Affiliation(s)
- Tomoyuki Kuwaki
- Department of Physiology; Kagoshima University Graduate School of Medical and Dental Sciences ; Kagoshima, Japan
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17
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Burke PGR, Abbott SBG, Coates MB, Viar KE, Stornetta RL, Guyenet PG. Optogenetic stimulation of adrenergic C1 neurons causes sleep state-dependent cardiorespiratory stimulation and arousal with sighs in rats. Am J Respir Crit Care Med 2015; 190:1301-10. [PMID: 25325789 DOI: 10.1164/rccm.201407-1262oc] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE The rostral ventrolateral medulla (RVLM) contains central respiratory chemoreceptors (retrotrapezoid nucleus, RTN) and the sympathoexcitatory, hypoxia-responsive C1 neurons. Simultaneous optogenetic stimulation of these neurons produces vigorous cardiorespiratory stimulation, sighing, and arousal from non-REM sleep. OBJECTIVES To identify the effects that result from selectively stimulating C1 cells. METHODS A Cre-dependent vector expressing channelrhodopsin 2 (ChR2) fused with enhanced yellow fluorescent protein or mCherry was injected into the RVLM of tyrosine hydroxylase (TH)-Cre rats. The response of ChR2-transduced neurons to light was examined in anesthetized rats. ChR2-transduced C1 neurons were photoactivated in conscious rats while EEG, neck muscle EMG, blood pressure (BP), and breathing were recorded. MEASUREMENTS AND MAIN RESULTS Most ChR2-expressing neurons (95%) contained C1 neuron markers and innervated the spinal cord. RTN neurons were not transduced. While the rats were under anesthesia, the C1 cells were faithfully activated by each light pulse up to 40 Hz. During quiet resting and non-REM sleep, C1 cell stimulation (20 s, 2-20 Hz) increased BP and respiratory frequency and produced sighs and arousal from non-REM sleep. Arousal was frequency-dependent (85% probability at 20 Hz). Stimulation during REM sleep increased BP, but had no effect on EEG or breathing. C1 cell-mediated breathing stimulation was occluded by hypoxia (12% FIO2), but was unchanged by 6% FiCO2. CONCLUSIONS C1 cell stimulation reproduces most effects of acute hypoxia, specifically cardiorespiratory stimulation, sighs, and arousal. C1 cell activation likely contributes to the sleep disruption and adverse autonomic consequences of sleep apnea. During hypoxia (awake) or REM sleep, C1 cell stimulation increases BP but no longer stimulates breathing.
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Affiliation(s)
- Peter G R Burke
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia
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Intermittent but not sustained hypoxia activates orexin-containing neurons in mice. Respir Physiol Neurobiol 2014; 206:11-4. [PMID: 25462014 DOI: 10.1016/j.resp.2014.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 10/20/2014] [Accepted: 11/05/2014] [Indexed: 11/22/2022]
Abstract
Hypothalamic orexin-containing neurons are activated by CO2 and contribute to hypercapnic ventilatory activation. However, their role in oxygen-related regulation of breathing is not well defined. In this study, we examined whether an experimental model mimicking apnea-induced repetitive hypoxemia (intermittent hypoxia [IH]) activates orexin-containing neurons. Mice were exposed to IH (5×5min at 10% O2), intermittent hyperoxia (IO; 5×5min at 50% O2), sustained hypoxia (SH; 25min at 10% O2), or sham stimulation. Their brains were examined using double immunohistochemical staining for orexin and c-Fos. The results indicated that IH (25.8±3.0%), but not SH (9.0±1.5%) activated orexin-containing neurons when compared to IO (5.5±0.6%) and sham stimulation (5.9±1.4%). These results correlate with those of our previous work showing that IH-induced respiratory long-term facilitation is dependent on orexin-containing neurons. Taken together, orexin contributes to repetitive hypoxia-induced respiratory activation and the hypoxic activation of orexin-containing neurons is pattern dependent.
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Mahler SV, Moorman DE, Smith RJ, James MH, Aston-Jones G. Motivational activation: a unifying hypothesis of orexin/hypocretin function. Nat Neurosci 2014; 17:1298-303. [PMID: 25254979 PMCID: PMC4335648 DOI: 10.1038/nn.3810] [Citation(s) in RCA: 264] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 08/19/2014] [Indexed: 12/15/2022]
Abstract
Orexins (hypocretins) are two peptides (orexin A and B) produced from the pre-pro-orexin precursor and expressed in a limited region of dorsolateral hypothalamus. Orexins were originally thought to specifically mediate feeding and promote wakefulness, but it is now clear that they participate in a wide range of behavioral and physiological processes under select circumstances. Orexins primarily mediate behavior under situations of high motivational relevance, such as during physiological need states, exposure to threats or reward opportunities. We hypothesize that many behavioral functions of orexins (including regulation of sleep/wake cycling) reflect a fundamentally integrated function for orexins in translating motivational activation into organized suites of psychological and physiological processes supporting adaptive behaviors. We also discuss how numerous forms of neural heterogeneity modulate this function, allowing orexin neurons to organize diverse, adaptive responses in a variety of motivationally relevant situations. Thus, the involvement of orexins in diverse behaviors may reflect a common underlying function for this peptide system.
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Affiliation(s)
- Stephen V Mahler
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina, USA
| | - David E Moorman
- 1] Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina, USA. [2] Department of Psychological and Brain Sciences, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Rachel J Smith
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Morgan H James
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Gary Aston-Jones
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina, USA
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Abstract
Lung ventilation fluctuates widely with behavior but arterial PCO2 remains stable. Under normal conditions, the chemoreflexes contribute to PaCO2 stability by producing small corrective cardiorespiratory adjustments mediated by lower brainstem circuits. Carotid body (CB) information reaches the respiratory pattern generator (RPG) via nucleus solitarius (NTS) glutamatergic neurons which also target rostral ventrolateral medulla (RVLM) presympathetic neurons thereby raising sympathetic nerve activity (SNA). Chemoreceptors also regulate presympathetic neurons and cardiovagal preganglionic neurons indirectly via inputs from the RPG. Secondary effects of chemoreceptors on the autonomic outflows result from changes in lung stretch afferent and baroreceptor activity. Central respiratory chemosensitivity is caused by direct effects of acid on neurons and indirect effects of CO2 via astrocytes. Central respiratory chemoreceptors are not definitively identified but the retrotrapezoid nucleus (RTN) is a particularly strong candidate. The absence of RTN likely causes severe central apneas in congenital central hypoventilation syndrome. Like other stressors, intense chemosensory stimuli produce arousal and activate circuits that are wake- or attention-promoting. Such pathways (e.g., locus coeruleus, raphe, and orexin system) modulate the chemoreflexes in a state-dependent manner and their activation by strong chemosensory stimuli intensifies these reflexes. In essential hypertension, obstructive sleep apnea and congestive heart failure, chronically elevated CB afferent activity contributes to raising SNA but breathing is unchanged or becomes periodic (severe CHF). Extreme CNS hypoxia produces a stereotyped cardiorespiratory response (gasping, increased SNA). The effects of these various pathologies on brainstem cardiorespiratory networks are discussed, special consideration being given to the interactions between central and peripheral chemoreflexes.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia
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Bochorishvili G, Nguyen T, Coates MB, Viar KE, Stornetta RL, Guyenet PG. The orexinergic neurons receive synaptic input from C1 cells in rats. J Comp Neurol 2014; 522:3834-46. [PMID: 24984694 DOI: 10.1002/cne.23643] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 06/25/2014] [Accepted: 06/27/2014] [Indexed: 11/10/2022]
Abstract
The C1 cells, located in the rostral ventrolateral medulla (RVLM), are activated by pain, hypoxia, hypoglycemia, infection, and hypotension and elicit cardiorespiratory stimulation, adrenaline and adrenocorticotropic hormone (ACTH) release, and arousal. The orexin neurons contribute to the autonomic responses to acute psychological stress. Here, using an anatomical approach, we consider whether the orexin neurons could also be contributing to the autonomic effects elicited by C1 neuron activation. Phenylethanolamine N-methyl transferase-immunoreactive (PNMT-ir) axons were detected among orexin-ir somata, and close appositions between PNMT-ir axonal varicosities and orexin-ir profiles were observed. The existence of synapses between PNMT-ir boutons labeled with diaminobenzidine and orexinergic neurons labeled with immunogold was confirmed by electron microscopy. We labeled RVLM neurons with a lentiviral vector that expresses the fusion protein ChR2-mCherry under the control of the catecholaminergic neuron-selective promoter PRSx8 and obtained light and ultrastructural evidence that these neurons innervate the orexin cells. By using a Cre-dependent adeno-associated vector and TH-Cre rats, we confirmed that the projection from RVLM catecholaminergic neurons to the orexinergic neurons originates predominantly from PNMT-ir catecholaminergic (i.e., C1 cells). The C1 neurons were found to establish predominantly asymmetric synapses with orexin-ir cell bodies or dendrites. These synapses were packed with small clear vesicles and also contained dense-core vesicles. In summary, the orexin neurons are among the hypothalamic neurons contacted and presumably excited by the C1 cells. The C1-orexin neuronal connection is probably one of several suprabulbar pathways through which the C1 neurons activate breathing and the circulation, raise blood glucose, and facilitate arousal from sleep.
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Kalsbeek A, la Fleur S, Fliers E. Circadian control of glucose metabolism. Mol Metab 2014; 3:372-83. [PMID: 24944897 PMCID: PMC4060304 DOI: 10.1016/j.molmet.2014.03.002] [Citation(s) in RCA: 203] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 03/05/2014] [Accepted: 03/07/2014] [Indexed: 01/15/2023] Open
Abstract
The incidence of obesity and type 2 diabetes mellitus (T2DM) has risen to epidemic proportions. The pathophysiology of T2DM is complex and involves insulin resistance, pancreatic β-cell dysfunction and visceral adiposity. It has been known for decades that a disruption of biological rhythms (which happens the most profoundly with shift work) increases the risk of developing obesity and T2DM. Recent evidence from basal studies has further sparked interest in the involvement of daily rhythms (and their disruption) in the development of obesity and T2DM. Most living organisms have molecular clocks in almost every tissue, which govern rhythmicity in many domains of physiology, such as rest/activity rhythms, feeding/fasting rhythms, and hormonal secretion. Here we present the latest research describing the specific role played by the molecular clock mechanism in the control of glucose metabolism and speculate on how disruption of these tissue clocks may lead to the disturbances in glucose homeostasis.
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Affiliation(s)
- Andries Kalsbeek
- Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, The Netherlands ; Hypothalamic Integration Mechanisms, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Susanne la Fleur
- Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, The Netherlands
| | - Eric Fliers
- Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, The Netherlands
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Abstract
There is increasing evidence that cardiovascular control during sleep is relevant for cardiovascular risk. This evidence warrants increased experimental efforts to understand the physiological mechanisms of such control. This review summarizes current knowledge on autonomic features of sleep states [non-rapid-eye-movement sleep (NREMS) and rapid-eye-movement sleep (REMS)] and proposes some testable hypotheses concerning the underlying neural circuits. The physiological reduction of blood pressure (BP) during the night (BP dipping phenomenon) is mainly caused by generalized cardiovascular deactivation and baroreflex resetting during NREMS, which, in turn, are primarily a consequence of central autonomic commands. Central commands during NREMS may involve the hypothalamic ventrolateral preoptic area, central thermoregulatory and central baroreflex pathways, and command neurons in the pons and midbrain. During REMS, opposing changes in vascular resistance in different regional beds have the net effect of increasing BP compared with that of NREMS. In addition, there are transient increases in BP and baroreflex suppression associated with bursts of brain and skeletal muscle activity during REMS. These effects are also primarily a consequence of central autonomic commands, which may involve the midbrain periaqueductal gray, the sublaterodorsal and peduncular pontine nuclei, and the vestibular and raphe obscurus medullary nuclei. A key role in permitting physiological changes in BP during sleep may be played by orexin peptides released by hypothalamic neurons, which target the postulated neural pathways of central autonomic commands during NREMS and REMS. Experimental verification of these hypotheses may help reveal which central neural pathways and mechanisms are most essential for sleep-related changes in cardiovascular function.
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Affiliation(s)
- Alessandro Silvani
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy; and
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Guyenet PG, Abbott SBG. Chemoreception and asphyxia-induced arousal. Respir Physiol Neurobiol 2013; 188:333-43. [PMID: 23608705 PMCID: PMC3749262 DOI: 10.1016/j.resp.2013.04.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/02/2013] [Accepted: 04/06/2013] [Indexed: 02/07/2023]
Abstract
Arousal protects against the adverse and potentially fatal effects of asphyxia during sleep. Asphyxia stimulates the carotid bodies and central chemoreceptors but the sequence of events leading to arousal is uncertain. In this review, the theoretical mechanisms leading to arousal from sleep are briefly summarized and the issue of whether central respiratory chemoreceptors (CRCs) or other types of CO2-responsive CNS neurons contribute to asphyxia-induced arousal is discussed. We focus on the role of the retrotrapezoid nucleus, the raphe and the locus coeruleus and emphasize the anatomical and neurophysiological evidence which suggests that these putative central chemoreceptors could contribute to arousal independently of their effects on breathing. Finally, we describe recent attempts to test the contribution of specific brainstem pathways to asphyxia-induced arousal using optogenetic and other tools and the possible contribution of a group of hypoxia-sensitive brainstem neurons (the C1 cells) to breathing and arousal.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, United States.
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Kuroki C, Takahashi Y, Ootsuka Y, Kanmura Y, Kuwaki T. The Impact of Hypothermia on Emergence from Isoflurane Anesthesia in Orexin Neuron-Ablated Mice. Anesth Analg 2013; 116:1001-1005. [DOI: 10.1213/ane.0b013e31828842f0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Shin YO, Lee JB, Min YK, Yang HM. Heat acclimation affects circulating levels of prostaglandin E2, COX-2 and orexin in humans. Neurosci Lett 2013; 542:17-20. [PMID: 23523649 DOI: 10.1016/j.neulet.2013.03.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2012] [Revised: 02/07/2013] [Accepted: 03/04/2013] [Indexed: 12/28/2022]
Abstract
We examined serum levels of prostaglandin E2 (PGE2), cyclooxygenase (COX)-2 and orexin before and after heat acclimation (HA) to test the hypothesis that decreased basal body temperature due to HA correlate with circulating levels of these key thermoregulatory molecules. Nine healthy human male volunteers were recruited (age, 21.9±2.7 years). The subjects were exposed to half-body immersion in hot water (42±0.5°C) at the same time of day (2-5p.m.) on alternate days for 3 weeks. The HA protocol included 10 bouts of 30min immersion. All experiments were performed in an automated climate chamber (temperature, 26.0±0.5°C; relative humidity, 60±3.0%; air velocity, <1m/s). Tympanic and skin temperatures were measured, and mean body temperature was calculated. The difference in body weight was used to estimate total sweat loss. Serum levels of PGE2, COX-2 and orexin were analyzed before and after HA. Body temperature decreased significantly (P<0.05) after HA, whereas sweat volume increased significantly (P<0.01). Serum PGE2, COX-2 and orexin concentrations decreased significantly compared to those at pre-acclimation (P<0.001, P<0.01, P<0.01, respectively). Our data suggest that decreased basal body temperature after HA is associated with decreases in thermoregulatory molecules, such as PGE2, COX-2 and orexin.
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Affiliation(s)
- Young Oh Shin
- Department of Healthcare, Global Graduate School, Soonchunhyang University, 646 Asan, Republic of Korea
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27
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Xiao F, Jiang M, Du D, Xia C, Wang J, Cao Y, Shen L, Zhu D. Orexin A regulates cardiovascular responses in stress-induced hypertensive rats. Neuropharmacology 2012; 67:16-24. [PMID: 23147417 DOI: 10.1016/j.neuropharm.2012.10.021] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 10/16/2012] [Accepted: 10/20/2012] [Indexed: 01/22/2023]
Abstract
Several pieces of evidence indicate that the rostral ventrolateral medulla (RVLM) is probably one of the key neural structures mediating the pressor effects of orexins in the brain. Nitric oxide synthase/nitric oxide (NOS/NO) system in the RVLM modulates cardiovascular activities. Our experiments were designed to test the hypothesis that orexin-A (OXA) is involved in the mechanism of stress-induced hypertension (SIH) by adjusting NOS/NO system in the RVLM. The stress-induced hypertensive rats (SIHR) model was established by electric foot-shocks and noises. Here we examined the expression of OXA immunoreactive (OXA-IR) cells in the lateral hypothalamus (LH) and the protein level of orexin 1 receptor (OX1R) in the RVLM of SIHR, and we found that the expressions of OXA-IR and OX1R were higher than those of the control group. The double-staining immunohistochemical evidence showed that OX1R immunoreactive (OX1R-IR) cells and neuronal nitric oxide synthase (nNOS) or inducible nitric oxide synthase (iNOS) immunoreactive (IR) cells were co-localizated in the RVLM. Microinjection of OXA (10, 50, 100 pmol/100 nl) into the unilateral (right) RVLM of control rats or SIHR produced pressor and tachycardiac effects in a dose-dependent manner. SB-408124 (100 pmol/100 nl, an antagonist of OX1R) or TCS OX2 29 (100 pmol/100 nl, an antagonist of OX2R) partly abolished the cardiovascular effects of exogenously-administrated OXA into the RVLM of control rats and SIHR, and lowered the increased systolic blood pressure (SBP) and heart rate (HR) of SIHR, with no difference in statistical significance between the two antagonists' effects. Microinjection into the RVLM of both control and SIHR groups of 7-Ni (0.05 pmol/100 nl, nNOS inhibitor) or Methylene Blue [100 pmol/100 nl, an inhibitor of soluble guanylate cyclase (sGC)] suppressed the OXA-induced increase of SBP and HR, whereas microinjection of AG (1, 10, 100 pmol/100 nl) had no obvious effects on the OXA-induced increase of SBP and HR. Our results indicate that OXA in the RVLM may participate in the central regulation of cardiovascular activities in SIHR, and OX1R and OX2R both have important roles in it. The cardiovascular effects of OXA in the RVLM may be induced by nNOS-derived NO, which activated sGC-associated signaling pathway.
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Affiliation(s)
- Fen Xiao
- Department of Physiology and Pathophysiology, Shanghai Medical College of Fudan University, 138 Yixueyuan Road, Shanghai 200032, PR China
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Stettner GM, Kubin L. Antagonism of orexin receptors in the posterior hypothalamus reduces hypoglossal and cardiorespiratory excitation from the perifornical hypothalamus. J Appl Physiol (1985) 2012; 114:119-30. [PMID: 23104701 DOI: 10.1152/japplphysiol.00965.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The perifornical (PF) region of the posterior hypothalamus promotes wakefulness and facilitates motor activity. In anesthetized rats, local disinhibition of PF neurons by GABA(A) receptor antagonists activates orexin (OX) neurons and elicits a systemic response, including increases of hypoglossal nerve activity (XIIa), respiratory rate, heart rate, and blood pressure. The increase of XIIa is mediated to hypoglossal (XII) motoneurons by pathways that do not require noradrenergic or serotonergic projections. We hypothesized that the pathway might include OX-dependent activation locally within the PF region or direct projections of OX neurons to the XII nucleus. Adult, male Sprague-Dawley rats were urethane anesthetized, vagotomized, paralyzed, and ventilated. Gabazine (GABA(A) receptor antagonist, 0.18 mM, 20 nl) was injected into the PF region, and ~2 h later, a second gabazine injection was performed preceded by injection of a dual OX1/2 receptor antagonist (almorexant; 90 mM) either into the XII nucleus (40-60 nl at 2-3 rostrocaudal levels; n = 6 rats), or into the PF region (40-60 nl; n = 6 rats). XIIa, respiratory rate, heart rate, and arterial blood pressure were analyzed for 70 min after each gabazine injection. The excitatory effects of PF gabazine on XIIa, respiratory, and heart rates were significantly reduced by up to 44-82% when gabazine injections were preceded by PF almorexant injections, but not when almorexant was injected into the XII nucleus. These data suggest that a significant portion of XII motoneuronal and cardiorespiratory activation evoked by disinhibition of PF neurons is mediated by local OX-dependent mechanisms within the posterior hypothalamus.
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Affiliation(s)
- Georg M Stettner
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6046, USA.
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29
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Karch SB. Possible Strategies for the Diagnosis of Fatal Excited Delirium Syndrome. Acad Forensic Pathol 2012. [DOI: 10.23907/2012.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Excited Delirium Syndrome (ExDS) is a term traditionally used in forensic literature to describe the symptoms and signs seen in a subgroup of patients with delirium who die in an agitated state. Components of this syndrome are altered mental status, combativeness and/or aggressiveness, increased tolerance to significant pain, tachypnea, profuse sweating, severe agitation, elevated temperature, delirium, and noncompliance with law enforcement and medical personnel. The individual may display “superhuman” strength and wear clothing inappropriate for the environment. Patients with this presentation are almost guaranteed to cause difficulties for law enforcement officers and medical staff. This review is written in hopes of minimizing some of these difficulties by 1) increasing general awareness and specific knowledge about this condition, 2) explaining the neurochemical and neuroanatomical alterations that have been shown to cause those symptoms, and 3) by suggesting new lines of research that might identify easily measured biomarkers for the disease. If the disease mechanism can be deciphered, then it should be possible to devise effective strategies for treatment. It would also be of enormous value to the legal system. When defending a diagnosis before the court, physical evidence always trumps knowledge and experience. It would be far better to be able to present physical proof than to opine that the decedent's behavior was typical for the disease. In this aspect, ExDS is analogous to myocardial infarction: if a man dies suddenly, it is much easier to prove the cardiac origin of the event if an occlusive thrombus is found in a major coronary artery.
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Affiliation(s)
- Steven B. Karch
- (Royal College of Physicians, London). Royal London Hospital and Cardiac Pathology at the Stanford Transplant Laboratory. San Francisco Medical Examiner
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Shahid IZ, Rahman AA, Pilowsky PM. Orexin A in rat rostral ventrolateral medulla is pressor, sympatho-excitatory, increases barosensitivity and attenuates the somato-sympathetic reflex. Br J Pharmacol 2012; 165:2292-303. [PMID: 21951179 DOI: 10.1111/j.1476-5381.2011.01694.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND AND PURPOSE The rostral ventrolateral medulla (RVLM) maintains sympathetic nerve activity (SNA), and integrates adaptive reflexes. Orexin A-immunoreactive neurones in the lateral hypothalamus project to the RVLM. Microinjection of orexin A into RVLM increases blood pressure and heart rate. However, the expression of orexin receptors, and effects of orexin A in the RVLM on splanchnic SNA (sSNA), respiration and adaptive reflexes are unknown. EXPERIMENTAL APPROACH The effect of orexin A on baseline cardio-respiratory variables as well as the somato-sympathetic, baroreceptor and chemoreceptor reflexes in RVLM were investigated in urethane-anaesthetized, vagotomized and artificially ventilated male Sprague-Dawley rats (n= 50). orexin A and its receptors were detected with fluorescence immunohistochemistry. KEY RESULTS Tyrosine hydroxylase-immunoreactive neurones in the RVLM were frequently co-localized with orexin 1 (OX(1) ) and orexin 2 (OX(2) ) receptors and closely apposed to orexin A-immunoreactive terminals. Orexin A injected into the RVLM was pressor and sympatho-excitatory. Peak effects were observed at 50 pmol with increased mean arterial pressure (42 mmHg) and SNA (45%). Responses to orexin A (50 pmol) were attenuated by the OX(1) receptor antagonist, SB334867, and reproduced by the OX(2) receptor agonist, [Ala(11) , D-Leu(15) ]orexin B. Orexin A attenuated the somato-sympathetic reflex but increased baroreflex sensitivity. Orexin A increased or reduced sympatho-excitation following hypoxia or hypercapnia respectively. CONCLUSIONS AND IMPLICATIONS Although central cardio-respiratory control mechanisms at rest do not rely on orexin, responses to adaptive stimuli are dramatically affected by the functional state of orexin receptors.
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Affiliation(s)
- Israt Z Shahid
- Australian School of Advanced Medicine, Macquarie University, Sydney, Australia
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Morairty SR, Revel FG, Malherbe P, Moreau JL, Valladao D, Wettstein JG, Kilduff TS, Borroni E. Dual hypocretin receptor antagonism is more effective for sleep promotion than antagonism of either receptor alone. PLoS One 2012; 7:e39131. [PMID: 22768296 PMCID: PMC3388080 DOI: 10.1371/journal.pone.0039131] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 05/16/2012] [Indexed: 01/16/2023] Open
Abstract
The hypocretin (orexin) system is involved in sleep/wake regulation, and antagonists of both hypocretin receptor type 1 (HCRTR1) and/or HCRTR2 are considered to be potential hypnotic medications. It is currently unclear whether blockade of either or both receptors is more effective for promoting sleep with minimal side effects. Accordingly, we compared the properties of selective HCRTR1 (SB-408124 and SB-334867) and HCRTR2 (EMPA) antagonists with that of the dual HCRTR1/R2 antagonist almorexant in the rat. All 4 antagonists bound to their respective receptors with high affinity and selectivity in vitro. Since in vivo pharmacokinetic experiments revealed poor brain penetration for SB-408124, SB-334867 was selected for subsequent in vivo studies. When injected in the mid-active phase, SB-334867 produced small increases in rapid-eye-movement (REM) and non-REM (NR) sleep. EMPA produced a significant increase in NR only at the highest dose studied. In contrast, almorexant decreased NR latency and increased both NR and REM proportionally throughout the subsequent 6 h without rebound wakefulness. The increased NR was due to a greater number of NR bouts; NR bout duration was unchanged. At the highest dose tested (100 mg/kg), almorexant fragmented sleep architecture by increasing the number of waking and REM bouts. No evidence of cataplexy was observed. HCRTR1 occupancy by almorexant declined 4–6 h post-administration while HCRTR2 occupancy was still elevated after 12 h, revealing a complex relationship between occupancy of HCRT receptors and sleep promotion. We conclude that dual HCRTR1/R2 blockade is more effective in promoting sleep than blockade of either HCRTR alone. In contrast to GABA receptor agonists which induce sleep by generalized inhibition, HCRTR antagonists seem to facilitate sleep by reducing waking “drive”.
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Affiliation(s)
- Stephen R Morairty
- Center for Neuroscience and Metabolic Disease Research, SRI International, Menlo Park, California, USA.
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Aran A, Shors I, Lin L, Mignot E, Schimmel MS. CSF levels of hypocretin-1 (orexin-A) peak during early infancy in humans. Sleep 2012; 35:187-91. [PMID: 22294808 PMCID: PMC3250357 DOI: 10.5665/sleep.1618] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Hypocretin (orexin) is a unique neuropeptide involved in the consolidation of wakefulness and sleep. Although hypocretin-1 levels in the cerebrospinal fluid (CSF) are stable after infancy, how levels change in preterm and term human infants is unknown. DESIGN, PATIENTS, AND SETTING Hypocretin-1 levels were measured in CSF samples, obtained from 284 preterm (25-37 gestational weeks) and full-term infants in the first 4 months of life and 35 older children (ages 0.5-13 years), in a tertiary hospital. MEASUREMENTS AND RESULTS Detailed clinical and laboratory data were collected for each of the 319 participants. Based on that data, 108 neurologically intact children were selected (95 infants [43 preterm and 52 term] and 13 older children). CSF hypocretin-1 was measured by direct radioimmunoassay. Hypocretin-1 levels at the first weeks of the 3rd embryonic trimester (gestational age [GA] 28-34 weeks) were 314 ± 65 pg/mL (n = 17). The levels linearly increased during the third trimester and early infancy (r = 0.6), peaking in infants of 2-4 months ages (476 ± 72 pg/mL; n = 16) and decreasing thereafter; hypocretin levels in 2- to 4-month-old infants were significantly higher than those in children 0.5-13 years old (353 ± 78 pg/mL, n = 13; P = 0.0001). CONCLUSIONS The present findings indicate that in human infants, CSF hypocretin-1 increases during the third embryonic trimester and is highest at 4 months of life. Thereafter, and consistent with previously published results, hypocretin levels are lower and stable until the geriatric age. This pattern may reflect the role of hypocretin in the dramatic process of sleep and wakefulness consolidation that occurs during early infancy.
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Affiliation(s)
- Adi Aran
- Neuropediatric Unit, Shaare Zedek Medical Center, Hebrew University, Jerusalem, Israel.
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Abstract
Stress increases cardiac function, ventilation, and body temperature and induces analgesia. These changes, which result in an increase in metabolic rate, oxygen supply, and the conduction velocity of nerve impulses, prepare the body for a fight-or-flight response. A part of the hypothalamus called the defense area has long been known to play a key role in these responses, but the precise mechanisms are largely unknown. Our recent findings suggest that orexin (hypocretin) neurons act as a master switch of the fight-or-flight response. In addition, our results, as well as those from other researchers, suggest that orexin neurons do not modulate specific behaviors such as the fight-or-flight responses but rather integrate the autonomic functions and behaviors in a broad sense or in a vigilance state-dependent manner. The orexin system seems to be a pivotal link between the subconscious and the conscious brain functions.
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Affiliation(s)
- Tomoyuki Kuwaki
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, Sakuragaoka, Kagoshima, Japan
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Yamanaka R, Yunoki T, Arimitsu T, Lian CS, Roghayyeh A, Matsuura R, Yano T. Relationship between effort sense and ventilatory response to intense exercise performed with reduced muscle glycogen. Eur J Appl Physiol 2011; 112:2149-62. [PMID: 21964911 DOI: 10.1007/s00421-011-2190-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2011] [Accepted: 09/20/2011] [Indexed: 11/30/2022]
Abstract
The purpose of the present study was to examine the effects of muscle glycogen reduction on surface electromyogram (EMG) activity and effort sense and ventilatory responses to intense exercise (IE). Eight subjects performed an IE test in which IE [100-105% of peak O(2) uptake ([Formula: see text]), 2 min] was repeated three times (IE(1st), IE(2nd) and IE(3rd)) at 100-120-min intervals. Each interval consisted of 20-min passive recovery, 40-min submaximal exercise at ventilatory threshold intensity (51.5 ± 2.7% of [Formula: see text]), and a further resting recovery for 40-60 min. Blood pH during IE and subsequent 20-min recovery was significantly higher in the IE(3rd) than in the IE(1st) (P < 0.05). Effort sense of legs during IE was significantly higher in the IE(3rd) than in the IE(1st) and IE(2nd). Integrated EMG (IEMG) measured in the vastus lateralis during IE was significantly lower in the IE(3rd) than in the IE(1st). In contrast, mean power frequency of the EMG was significantly higher in the IE(2nd) and the IE(3rd) than in the IE(1st). Ventilation ([Formula: see text]) in the IE(3rd) was significantly higher than that in the IE(1st) during IE and the first 60 s after the end of IE. These results suggest that ventilatory response to IE is independent of metabolic acidosis and at least partly associated with effort sense elicited by recruitment of type II fibers.
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Affiliation(s)
- Ryo Yamanaka
- Graduate School of Education, Hokkaido University, Kita-11, Nishi-7, Kita-ku, Sapporo 060-0811, Japan.
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Fanfulla F, Ceriana P, D'Artavilla Lupo N, Trentin R, Frigerio F, Nava S. Sleep disturbances in patients admitted to a step-down unit after ICU discharge: the role of mechanical ventilation. Sleep 2011; 34:355-62. [PMID: 21358853 DOI: 10.1093/sleep/34.3.355] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Severe sleep disruption is a well-documented problem in mechanically ventilated, critically ill patients during their time in the intensive care unit (ICU), but little attention has been paid to the period when these patients become clinically stable and are transferred to a step-down unit (SDU). We monitored the 24-h sleep pattern in 2 groups of patients, one on mechanical ventilation and the other breathing spontaneously, admitted to our SDU to assess the presence of sleep abnormalities and their association with mechanical ventilation. METHODS Twenty-two patients admitted to an SDU underwent 24-h polysomnography with monitoring of noise and light. RESULTS One patient did not complete the study. At night, 10 patients showed reduced sleep efficiency, 6 had reduced percentage of REM sleep, and 3 had reduced percentage of slow wave sleep (SWS). Sleep amount and quality did not differ between patients breathing spontaneously and those on mechanical ventilation. Clinical severity (SAPS(II) score) was significantly correlated with daytime total sleep time and efficiency (r = 0.51 and 0.5, P < 0.05, respectively); higher pH was correlated with reduced sleep quantity and quality; and higher PaO(2) was correlated with increased SWS (r = 0.49; P = 0.02). CONCLUSIONS Patients admitted to an SDU after discharge from an ICU still have a wide range of sleep abnormalities. These abnormalities are mainly associated with a high severity score and alkalosis. Mechanical ventilation does not appear to be a primary cause of sleep impairment.
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Affiliation(s)
- Francesco Fanfulla
- Sleep Center, Istituto Scientifico di Pavia and Montescano, Fondazione S. Maugeri, IRCCS, Pavia, Italy.
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Dick TE, Pilowsky PM. Foreword. Respir Physiol Neurobiol 2010; 174:1-3. [DOI: 10.1016/j.resp.2010.09.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 09/29/2010] [Indexed: 11/15/2022]
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