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Csernai M, Borbély S, Kocsis K, Burka D, Fekete Z, Balogh V, Káli S, Emri Z, Barthó P. Dynamics of sleep oscillations is coupled to brain temperature on multiple scales. J Physiol 2019; 597:4069-4086. [PMID: 31197831 DOI: 10.1113/jp277664] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 06/11/2019] [Indexed: 01/23/2023] Open
Abstract
KEY POINTS Sleep spindle frequency positively, duration negatively correlates with brain temperature. Local heating of the thalamus produces similar effects in the heated area. Thalamic network model corroborates temperature dependence of sleep spindle frequency. Brain temperature shows spontaneous microfluctuations during both anesthesia and natural sleep. Larger fluctuations are associated with epochs of REM sleep. Smaller fluctuations correspond to the alteration of spindling and delta epochs of infra-slow oscillation. ABSTRACT Every form of neural activity depends on temperature, yet its relationship to brain rhythms is poorly understood. In this work we examined how sleep spindles are influenced by changing brain temperatures and how brain temperature is influenced by sleep oscillations. We employed a novel thermoelectrode designed for measuring temperature while recording neural activity. We found that spindle frequency is positively correlated and duration negatively correlated with brain temperature. Local heating of the thalamus replicated the temperature dependence of spindle parameters in the heated area only, suggesting biophysical rather than global modulatory mechanisms, a finding also supported by a thalamic network model. Finally, we show that switches between oscillatory states also influence brain temperature on a shorter and smaller scale. Epochs of paradoxical sleep as well as the infra-slow oscillation were associated with brain temperature fluctuations below 0.2°C. Our results highlight that brain temperature is massively intertwined with sleep oscillations on various time scales.
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Affiliation(s)
- Márton Csernai
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Sándor Borbély
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.,Department of Physiology and Neurobiology, Eötvös Loránd University, Budapest, Hungary
| | - Kinga Kocsis
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.,Roska Tamás Doctoral School of Sciences and Technology, Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary.,Neuronal Network and Behavior Research Group, RCNS, Hungarian Academy of Sciences, Budapest, Hungary
| | - Dávid Burka
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.,Corvinus University of Budapest, Budapest, Hungary
| | - Zoltán Fekete
- Research Group for Implantable Microsystems, Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary.,Institute of Technical Physics and Material Science, Centre for Energy Research, Hungarian Academy of Sciences, Budapest, Hungary
| | - Veronika Balogh
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Szabolcs Káli
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | | | - Péter Barthó
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
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Development and validation of brain target controlled infusion of propofol in mice. PLoS One 2018; 13:e0194949. [PMID: 29684039 PMCID: PMC5912730 DOI: 10.1371/journal.pone.0194949] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 03/13/2018] [Indexed: 12/25/2022] Open
Abstract
Mechanisms through which anesthetics disrupt neuronal activity are incompletely understood. In order to study anesthetic mechanisms in the intact brain, tight control over anesthetic pharmacology in a genetically and neurophysiologically accessible animal model is essential. Here, we developed a pharmacokinetic model that quantitatively describes propofol distribution into and elimination out of the brain. To develop the model, we used jugular venous catheters to infuse propofol in mice and measured propofol concentration in serial timed brain and blood samples using high performance liquid chromatography (HPLC). We then used adaptive fitting procedures to find parameters of a three compartment pharmacokinetic model such that all measurements collected in the blood and in the brain across different infusion schemes are fit by a single model. The purpose of the model was to develop target controlled infusion (TCI) capable of maintaining constant brain propofol concentration at the desired level. We validated the model for two different targeted concentrations in independent cohorts of experiments not used for model fitting. The predictions made by the model were unbiased, and the measured brain concentration was indistinguishable from the targeted concentration. We also verified that at the targeted concentration, state of anesthesia evidenced by slowing of the electroencephalogram and behavioral unresponsiveness was attained. Thus, we developed a useful tool for performing experiments necessitating use of anesthetics and for the investigation of mechanisms of action of propofol in mice.
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Wiater MF, Mukherjee S, Li AJ, Dinh TT, Rooney EM, Simasko SM, Ritter S. Circadian integration of sleep-wake and feeding requires NPY receptor-expressing neurons in the mediobasal hypothalamus. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1569-83. [PMID: 21880863 DOI: 10.1152/ajpregu.00168.2011] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Sleep and feeding rhythms are highly coordinated across the circadian cycle, but the brain sites responsible for this coordination are unknown. We examined the role of neuropeptide Y (NPY) receptor-expressing neurons in the mediobasal hypothalamus (MBH) in this process by injecting the targeted toxin, NPY-saporin (NPY-SAP), into the arcuate nucleus (Arc). NPY-SAP-lesioned rats were initially hyperphagic, became obese, exhibited sustained disruption of circadian feeding patterns, and had abnormal circadian distribution of sleep-wake patterns. Total amounts of rapid eye movement sleep (REMS) and non-REMS (NREMS) were not altered by NPY-SAP lesions, but a peak amount of REMS was permanently displaced to the dark period, and circadian variation in NREMS was eliminated. The phase reversal of REMS to the dark period by the lesion suggests that REMS timing is independently linked to the function of MBH NPY receptor-expressing neurons and is not dependent on NREMS pattern, which was altered but not phase reversed by the lesion. Sleep-wake patterns were altered in controls by restricting feeding to the light period, but were not altered in NPY-SAP rats by restricting feeding to either the light or dark period, indicating that disturbed sleep-wake patterns in lesioned rats were not secondary to changes in food intake. Sleep abnormalities persisted even after hyperphagia abated during the static phase of the lesion. Results suggest that the MBH is required for the essential task of integrating sleep-wake and feeding rhythms, a function that allows animals to accommodate changeable patterns of food availability. NPY receptor-expressing neurons are key components of this integrative function.
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Affiliation(s)
- M F Wiater
- Programs in Neuroscience, Dept. of Veterinary and Comparative Anatomy, Physiology and Pharmacology, Washington State Univ., Pullman, WA 99164-6520, USA.
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Peterfi Z, McGinty D, Sarai E, Szymusiak R. Growth hormone-releasing hormone activates sleep regulatory neurons of the rat preoptic hypothalamus. Am J Physiol Regul Integr Comp Physiol 2009; 298:R147-56. [PMID: 19889861 DOI: 10.1152/ajpregu.00494.2009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined whether growth hormone-releasing hormone (GHRH) may promote non-rapid eye movement (NREM) sleep via activation of GABAergic neurons in the preoptic area. Male Sprague-Dawley rats were implanted with EEG, EMG electrodes and a unilateral intracerebroventricular cannula. Groups of rats received injections (3 microl icv) with gonadotropin-releasing hormone (GHRH) (0.1 nmol/100 g body wt) or equal volume of physiological saline at the onset of the dark period and were permitted spontaneous sleep for 90 min. Separate groups of rats were sleep deprived by gentle handling for 90 min, beginning at the time of GHRH or saline injection, at the onset of the dark period. Other groups of rats received intracerebroventricular octreotide (somatostatin analog OCT) injections, intracerebroventricular injection of one of two doses of competitive GHRH antagonist, or intracerebroventricular saline injection at light onset and were then permitted 90 min spontaneous sleep-waking. Rats were killed immediately after the 90-min sleep/wake monitoring period. Brain tissue was processed for immunohistochemistry for c-Fos protein and glutamic acid decarboxylase (GAD). Single c-Fos and dual Fos-GAD cell counts were determined in the median preoptic nucleus (MnPN), and in the core and the extended parts of the ventrolateral preoptic nucleus (cVLPO and exVLPO). Intracerebroventricular GHRH elicited a significant increase in NREM sleep amount. Double-labeled Fos+GAD cell counts were significantly elevated after GHRH injection in the MnPN and VLPO in both undisturbed and sleep-deprived groups. OCT and GHRH antagonist significantly decreased NREM sleep amount compared with control rats. OCT injection increased single c-Fos-labeled cell counts in the MnPN, but not in the VLPO. Double-labeled cell counts were significantly reduced after OCT and the high dose of GHRH antagonist injection in all areas examined. These findings identify GABAergic neurons in the MnPN and VLPO as potential targets of the sleep-regulatory actions of GHRH.
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Affiliation(s)
- Zoltan Peterfi
- Research Service (151A3), VA Greater Los Angeles Healthcare System, 16111 Plummer St., North Hills, CA 91344, USA
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