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Interplay between adenosine signaling and the circadian system
Škrle, Jan ; Bendová, Zdeňka (advisor) ; Houdek, Pavel (referee)
Sleep is regulated primarily by the two processes, by Process C and S. Process C represents circadian regulation by circadian system; Process S represents the homeostatic sleep drive. Circadian system controls the timing of many physiological functions including body temperature rhythms, locomotor activity rhythms, periodically changing hormones levels etc. Process C contributes to sleep regulation mainly by setting lower and upper thresholds for a sleep pressure. When the sleep pressure reaches one of these thresholds, falling asleep or waking is promoted. However, the sleep architecture is altered by a phase of endogenous oscillators as well. The homeostatic sleep drive is based on a sleep- wake history with the sleep pressure rising during a wakefulness and lowering during sleep. This mechanism is responsible for a modification in structure of a recovery sleep following a sleep deprivation. Due to the effects of adenosine on sleep regulation, adenosine signalling is considered to play a critical role in the homeostatic sleep drive. These two processes were thought to be independent of each other, but new data show that there is a reciprocal regulation between them. The aim of this work was to conclude, where these two processes meet, with a special attention on processes, where the adenosine...
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Synchronization of circadian clock in hippocampus
Kubátová, Eliška ; Sumová, Alena (advisor) ; Liška, Karolína (referee)
Circadian rhythms refer to the physiological, biochemical and behavioral changes of the organism with a period of about 24 hours, such as the cycle of sleep and wakefulness, the release of hormones, enzymatic activity or gene expression. Apart from the central pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus, we find many other peripheral oscillators in which we observe the rhythmic expression of clock genes. In this study, we focused on one of the peripheral brain oscillators located in the hippocampus. The hippocampus is best known for its role in memory formation through the mechanism of long- term potentiation (LTP). The formation of LTP is another process that exhibits circadian variation. Although the rhythmic expression of genes in the hippocampus has already been demonstrated, the mechanisms of synchronization of these clocks remain a subject of investigation. In this study, we studied the effect of candidate substances - N-methyl-D- aspartate (NMDA) and leptin on the circadian clock of the hippocampus. Genetically modified mPer2Luc mice were used as a model. The main goal of the work was to introduce a method of preparing organotypic explants of the hippocampus of these mice for monitoring the circadian clock in real time using the LumiCycle device. Next goal was...
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Circadian system and reproduction
Hrubá, Anežka ; Lužná, Vendula (advisor) ; Ladislavová, Lucie (referee)
Due to the alternation of day and night, mammals have developed internal circadian clocks, helping to synchronize physiological processes with the external environment. The circadian system is hierarchically organized, with central clocks located within suprachiasmatic nuclei of the hypothalamus (SCN). The main signal for setting the clocks to the external time is light, which enters the SCN through retina. The SCN communicate with peripheral oscillators in other organs, including reproductive ones, via hormonal signals, thereby synchronizing a variety of physiological processes. At the molecular level, clocks are controlled by clock genes. Cicradian system has a significant impact on reproduction. It is manifested by rythmical expression of clock genes and production of hormones in reproductive organs, as well as a success in reproduction if the clock's function is proper, and problems with reproduction if it is not. From a gender perspective, a several differences between women and men has been found throughout the SCN. Likewise, there are differences in chronotypes between both sexes over the course of their lives. Biological rhythms also include circannual rhythms, contributing to the timing of reproduction at the proper season of the year. Animals mate at different time depending on the length...
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Regular physical activity as a circadian Zeitgeber
Fenclová, Aneta ; Bendová, Zdeňka (advisor) ; Červená, Kateřina (referee)
The function of almost every cell in the body is regulated by the circadian system. At the whole-body level, this system consists of the main oscillator, which is formed by the suprachiasmatic nucleus of the hypothalamus, and peripheral oscillators of individual organs and tissues. This system is sensitive to periodic changes in the external environment, particularly to the alternation of light and darkness, and under unfavorable lighting conditions, it can lead to desynchronization of both this timing system with the solar cycle and the mutual desynchronization of individual organs and tissues. This temporal mismatch of physiological processes can cause a range of diseases and metabolic disorders, and can be partially prevented by regular physical activity. Daily oscillations of circadian rhythms in many cardiovascular and metabolic parameters also determine the ideal time of day for anaerobic performance. This bachelor's thesis is a selection and comparison of information from professional literature and available studies dealing with the mutual influence of physical activity and circadian rhythms. There are works mentioned here that test the effect of physical activity on internal desynchronization of the melatonin rhythm and sleep pattern, on the circadian synchronization of skeletal muscle, as...
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Circadian rhythms in adipocytes and impact of their disruption
Zavřelová, Michaela ; Sumová, Alena (advisor) ; Spišská, Veronika (referee)
This bachelor thesis deals with circadian rhythms in adipocytes and the consequences of their disruption. The thesis summarizes current scientific knowledge and explores the mechanism of rhythm control at the molecular level, which is formed by transcriptional translational feedback loops. Adipocytes control lipid metabolism through the production of adipokines, adipogenesis, lipogenesis, and lipolysis. The research focuses on how clock genes are involved in these processes. All of these events, which are characteristic of adipocytes, are highly regulated and the genes that are involved in them are transcriptionally activated by clock gene proteins. Circadian rhythms are an integral part of our lives, and desynchronization of rhythms between the main oscillator, which is the suprachiasmatic nuclei, and peripheral adipocytes can lead to metabolic disorders, which in turn can lead to obesity, insulin resistance, or type 2 diabetes. Obesity is one of the biggest problems of modern society, and disrupted circadian rhythms due to today's lifestyle are one of the causes of its development. Key words: circadian rhythms, clock genes, adipocytes, obesity, PPARγ, adipogenesis, lipogenesis, lipolysis, leptin, adiponectin
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The effect of long-term morphine application on clock genes expression in the rat brain
Pačesová, Dominika ; Bendová, Zdeňka (advisor) ; Roubalová, Lenka (referee) ; Polidarová, Lenka (referee)
The circadian and opioid systems are systems involved in maintaining homeostasis in the body. Disruption of the circadian system disturbs the proper timing of physiological processes, which can result in the development or exacerbation of pre-existing pathological conditions, including addiction. One of the factors that can influence the precise synchronization of the circadian system is the use and abuse of opioids. The interrelationship between the circadian and opioid systems is poorly studied. To this end, the present study investigated the effect of morphine and methadone on the rat circadian system in adulthood and during development. The aim of this dissertation was to observe the effect of acute morphine administration on the expression of clock genes in the suprachiasmatic nuclei (SCN) of adult rats, and to investigate the effect of long-term morphine or methadone administration and withdrawal on the expression of clock genes in the SCN and on the activity of the enzyme AA-NAT in the pineal gland of adult rats. Proper development of the circadian clock contributes significantly to the maintenance of health in adulthood and ensures good adaptability of the organism to changes in the external environment. No study to date has focused on examining the effects of opioid administration during...
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The role of posttranslational modifications in the molecular mechanism of the circadian clock
Janáčová, Klára ; Sumová, Alena (advisor) ; Sládek, Martin (referee)
The timing of the biological processes of organism is controlled by an endogenous circadian clock. The molecular clock is present in almost every cell and is synchronized with the external environment. The main mechanism of the clock is a transcription-translation feedback loop. The 24-hour circadian rhythm period is provided by reversible posttranslational modifications (PTMs) of the clock proteins and another regulators of the circadian clock. PTMs are further important for clock entrainment, their regulation by metabolic state in the cell, and reciprocal regulation of the circadian clock end cell cycle. Phosphorylation, histones PTMs, acetylation, SUMOylation, ubiquitination, O-linked N-acetylglucosamination and polyADP-ribosylation play a crucial role. The molecular mechanism of the biological clock is an evolutionarily conserved mechanism found in most organisms. This bachelor thesis summarizes the knowledge about the role of PTMs in the molecular mechanism of the mammalian and human circadian clocks. Key words: circadian clock, clock genes, clock proteins, posttranslational modifications
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Circadian regulation of the cardiovascular system
Nováková, Jessica ; Bendová, Zdeňka (advisor) ; Galatík, František (referee)
Circadian system consist of the main circadian oscillator and the peripheral oscillators. Their function is to enable the adaptation of living organisms to the diurnal environmental changes. Circadian system regulates rhythmical expression of genes in nearly every cell of the body, thereby affecting both the physiological and behavioural processes of mammals and other animals. This bachelor's thesis summarizes a knowledge from experiments which led to the demonstration of circadian rhytms in cardiovascular system. To introduce the topic, the first discoveries of circadian rhythms in the cardiovascular system are mentioned. Then, we focus on the circadian rhythms in cardiomyocytes, vascular endothelial cells and in vascular smooth muscle cells. Another focal point of my thesis is the role of transcription factor Krüppel-like factor 15. Circadian regulation of the cardiovascular system is important for the proper function of the heart and blood vessels. Circadian disruption can cause severe pathophysiological and cardiovascular conditions, such as ventricular hypertrophy, hypertension, atherosclerosis, myocardial infarction or coronary artery disease. Key words: circadian, clock genes, cardiovascular system, cardiomyocytes, vascular endothelial cells, vascular smooth muscle cells, Krüppel-like factor...
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Internal communication within the circadian system and its significance for our health
Honzlová, Petra ; Sumová, Alena (advisor) ; Moravcová, Simona (referee)
Mammalian circadian cycle is generated by hierarchically organized system of internal rhythmical oscillations in clock gene expression (Clock, Bmal1, Per, Cry, Rev-Erb, etc.) which take place in nearly all living cells in our body. The master pacemaker is located in suprachiasmatic nucleus (SCN) in hypothalamus. According to its synchronization to photic and non-photic external stimuli SCN generates signal for entrainment of peripheral clock. Peripheral clock synchronization is maintained via neuronal or hormonal (glucocorticoids, melatonin) pathways, regulation of body temperature or food intake and affects various physiological processes. Desynchronization of central and peripheral clock can be the cause or the manifestation of impaired health condition. Powered by TCPDF (www.tcpdf.org)
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Circadian system in bulbus olfactorius
Kyclerová, Hana ; Bendová, Zdeňka (advisor) ; Polidarová, Lenka (referee)
The mammalian circadian system is composed of major circadian pacemaker located in the hypothalamic suprachiasmatic nuclei and peripheral circadian oscillators. Molecular mechanism of interlocked transcription-translation feedback loops, as a characteristic of each circadian oscillator, results in circadian rhythms. Peripheral oscillators in other brain parts and body organs are driven by the signals from the suprachiasmatic nuclei. Some structures however generate oscillations independently from the major circadian pacemaker. The best described of them resides in the mammalian retina. The retinal circadian oscillator regulates local rhythmic synthesis of melatonin, retinal pH and photoreceptors viability. Recently, some studies occur charactering the existence of such an independent circadian oscillator also in bulbus olfactorius. For example, the olfactory bulb circadian oscillator drives olfactory sensitivity during the day. Studies about development of the mamalian circadian system have shown that the olfactory bulb circadian oscillator matures earlier than the major circadian pacemaker and represents its function during early development. Powered by TCPDF (www.tcpdf.org)
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