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Significance of the timekeeping system for human health
Pospíšilová, Lucie ; Sumová, Alena (advisor) ; Hejnová, Lucie (referee)
The circadian system evolved as an adaptation to cyclic changes in external conditions on Earth, mainly the alternation of light and dark with a period of solar day. The rhythmic signal is generated at the cellular level and it is controlled by rhythmic expression of clock genes and their protein products. In mammals, the hypothalamic suprachiasmatic nuclei (SCN) are the principal circadian oscillator coordinating daily cycles of physiology and behavior, while in peripheral tissues local oscillators operate. The peripheral oscillators are entrained to the daytime and also among each other, by neuroendocrine signals from the SCN. Mutual synchrony of all the circadian components is necessary for proper function of the organism. The main entraining cue of the circadian system with environment is light, which affect the SCN via retina. In a subgroup of blind people sensing the light in the retina is disturbed and their circadian system cannot be synchronized by light. The SCN controls rhythmic production of melatonin in the pineal gland. This hormone mediates the information about the daytime to other tissues in the body, which are not photosensitive. The circadian system temporally drives many processes, including the cell division cycle. It seems that disruption of the temporal regulation could contribute to...
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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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The disruption of the circadian system in bipolar disorder and its association with the polymorphism of L-type calcium channel
Filipovská, Eva ; Bendová, Zdeňka (advisor) ; Novosadová, Zuzana (referee)
Bipolar affective disorder is a serious psychiatric disease with prevalence of about 1% in general population. Typical symptoms are mood changes: manic periods are followed by depressions, with possible asymptomatic period of variable duration between them. It alters patient's everyday life and often leads to suicidal tendencies. Bipolar disorder is related to impaired circadian rhytms that are regulated from suprachiasmatic nuclei in hypothalamus. Impaired circadian rhytms in bipolar disorder are manifested by abnormalities of sleep and daily activity and by disrupted circadian secretion of several hormons. One of many factors that link bipolar disorder to circadian system at molecular level is the function of voltage-dependent calcium channels of L-type. Expression of these channels is regulated by the clock genes and their proper function is important for maintaining endogenous oscillations in the main oscillator located in suprachiasmatic nuclei. A common finding in patients with bipolar disorder is polymorphism of the gene for 1 subunit of the Cav1.2 channel. Abnormal function of calcium channels, consequent to the polymorphism, may be one of the causes that alter circadian rhytms in bipolar disorder. Key words: circadian system, suprachiasmatic nucleus, bipolar disorder, L-type calcium...
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The Circadian System and Sleep in Individuals with ADHD
Nejedlý, Martin ; Skálová, Kateřina (advisor) ; Honzlová, Petra (referee)
Attention-Deficit/Hyperactivity Disorder (ADHD) is associated with sleep disorders and abnormalities of the circadian system. In recent studies, ADHD has been linked to late chronotype and delayed sleep phase disorder, clock gene polymorphisms, geographic variation in solar irradiation, longer sleep latency, and impaired sleep quality. However, research findings in children with ADHD often differ from those in adult patients. A new diagnostic category, ADHD-SOM, has been proposed to describe individuals whose symptoms are partially caused by chronic sleep issues. However, most of the evidence is correlational. The thesis summarizes research on sleep and circadian correlates of ADHD and some of the potential mechanisms explaining these associations. Chronotherapy and sleep interventions are promising methods of adjunctive ADHD treatment.
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Association of selected polymorphisms with clock genes with a extreme chronotypes
Turečková, Lucie ; Bendová, Zdeňka (advisor) ; Weissová, Kamila (referee)
The circadian system has evolved in organisms as an adaptation to periodic changes in the environment. Its task is to ensure regular entrainment between the solar cycle and the internal period of the organism, and to generate signals that synchronize behavioral and physiological processes in the body with the solar cycle. The whole mechanism takes place at the cell level, where there are regular oscillations of the transcriptional translation loops of the clock genes occur within 24 hours, thus ensuring a regular rhythm of the organism. However, the circadian system may not generate the same length of period in humans and may differ in the degree of entrainment with the external cycle. Base on that there are developed so-called individual time preferences. These different preferences are referred to as chronotypes, which fall into five categories: extremely evening, moderate evening, intermediate, moderate morning, and extremely morning type. Clock gene polymorphisms are considered to be one of the possible causes of these differences. The association of selected clock gene polymorphisms with extreme chronotypes is the subject of this diploma thesis. We obtained a saliva sample for DNA isolation from volunteers with extreme chronotypes. Using molecular methods of PCR, restriction digest and...
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Evaluation of Biological Efficiency of Pilot Installation of Biodynamic Lighting in a Retirement Home
Halászová, Andrea ; Bendová, Zdeňka (advisor) ; Jelínková, Dana (referee)
Many actions we observe in nature show some kind of regularity, therefore we call them rhytms. Rhytms with a period of approximately 24 hours, so called circadian rhytms, can be distinguished in many physiological processes, with the sleep-wake cycle being one of the most prominent ones. Light is the main exogenous circadian synchronizator and thanks to the circadian rhytm influence on physiological function, it's also often spoken about an influence of light on the entire organism. Nowadays, when we spend most of the day indoors under artificial light, we often suffer from a lack of natural daylight and its synchronizing potential. This is even more prominent in elderly population living in nursing homes and in other social facilities. Lately, a new type of lighting, so called biodynamic, has been introduced. Biodynamic lighting can simulate changes in natural light conditions throughout the day and therefore partially compensate for the lack of natural daylight we suffer from, and also minimize risks of the night light. In this study we aimed to test changes in the circadian system of seniors living in the Retirement Home of TGM in Beroun using questionnaires and circadian markers. We have shown a positive effect of the installed biodynamic lighting on our participants' circadian markers and...
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Development of the rat circadian system under constant light conditions
Petrželková, Lucie ; Bendová, Zdeňka (advisor) ; Kopřivová, Jana (referee)
The circadian system is a mechanism designed to generate circadian time and to synchronize it with the solar cycle. Its function is to adjust to behavioral and physiological function with the 24-hour period. The adjustment is performed using a so-called zeitgeber or synchronizer. The main circadian clock is in the suprachiasmatic nuclei (SCN) in the hypothalamus. Prolonged exposure of the organism to constant light conditions results in desynchronization of the circadian clock, which can lead to many pathologies. The impact of light at night on the organism has been studied for a long time, but the question of the impact of constant light on the development of the circadian system of the organism has been less studied. My thesis deals with this issue. Using RT-qPCR I investigated how the rhytm changes in the expression of selected clock genes in selected parts of the rat's brain, which has been kept in constant light sice birth. I also tested the impact of exposure to constant light on the early development of rhytm in locomotor activity later in the rat's life. Keywords: circadian system, photic entrainment, desynchronization under constant light, development, rat
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Circadian system in astrocytes
Ľalíková, Kristýna ; Bendová, Zdeňka (advisor) ; Honc, Ondřej (referee)
The circadian system affects almost all cells in the mammalian body. These cells include astrocytes, which together with microglia and oligodendrocytes represent the main types of glial cells found in the brain. The first chapter of this thesis presents a summary of circadian system characteristics and focuses mainly on the molecular mechanism underlying its functioning. The second chapter is devoted to astrocytes, astrocyte calcium signaling, and the process of gliotransmission. The third and last chapter connects both topics and discusses the circadian system in astrocytes. It presents evidence of astrocytic circadian oscillations existence and physiological consequences of its action. Great attention is paid to circadian rhythms in gliotransmission, with a focus on gliotransmitters ATP and glutamate. As the most impressive output of the circadian system of astrocytes is presented the participation in maintaining the rhythmic activity of the main circadian oscillator located in the suprachiasmatic nucleus of the hypothalamus. Key words: circadian system, clock genes, astrocytes, gliotransmission, calcium signaling, glutamate, ATP
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Expression of enzymes of kynurenine and methoxyindole pathway in the rat pineal gland, liver and heart in circadian profile and after lipopolysacharide administration
Hrubcová, Leona ; Bendová, Zdeňka (advisor) ; Svobodová, Irena (referee)
Tryptophanis anaminoacidwhichhasmanyfunctionsinthebody. Besidesitsparticipationin theproductionofproteins,itactsasasubstrateforthekynurenineandmethoxyindolemetabolic pathways. The kynurenine pathway ends with the production of nikotinamid e adenin dinukleotide ( NAD + ) ,whichisneededfortheproductionofcellularenergy. Thus,withincreased energy demand during immune system activation, the activity of the kynurenine pathway is increased. Dueto increasedactivity,itproduces more immunoactiveandneuroactivemetab olites suchaskynurenicacidandquinolinicacid.Thesemetabolitesareinvolvedinmanyprocessesin the body and affect the pathology of many diseases. Studies show that regulation of these metabolites could be a key innovation in the treatment of cance r, cardiovascular or neurodegenerative diseases. The methoxyindole pathway is another important tryptophan processingpathway.Itsbest - knownmetabolitesareserotonin,whichactsasaneurotransmitter, andmelatonin,ahormonewithimmunomodulatoryeffect sregulatedby thecircadianclock . This workdeals with thecircadian rhythmicityofenzymeexpressionofthesetwo metabolic pathways.Italsodescribestheeffectofsystemicadministrationoflipopolysaccharideendotoxin ontheexpressionofgenesoft heseenzymes.OurexperimentsusedWistarratsat30daysofage. The lipopolysaccharide was administered...
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Impact of light on cognition and mood
Křivohlavá, Tereza ; Bendová, Zdeňka (advisor) ; Růžička, Jiří (referee)
Circadian rhythms are cyclically repeating biorhythms with an approximate period of 24 hours. The main circadian pacemaker located in the suprachiasmatic nuclei in the hypothalamus controls the correct timing of physiological processes and behaviors and works to synchronize the whole body into a single period. The circadian clock works correctly if the period and phase are adjusted daily by environmental stimuli consistent with the solar cycle. The alternation of light and dark is the primary synchronizer of circadian rhythms and one that people mostly do not adhere nowadays. At nighttime they are usually exposed to strong lights while during the daytime they spend many hours in a dark room without receiving enough (sun)light. This disruption of biological and environmental clocks causes the desynchronization of the organism and the periodic misalignment of physiological or mental processes in the body. Long lasting desynchronization could have a serious impact on the human body, including emotions and cognitive functions.
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