|
|
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...
|
|
|
The relationship between circadian system and cell cycle
Vrtílková, Andrea ; Bendová, Zdeňka (advisor) ; Fárková, Eva (referee)
The circadian system is able to oscillate by itself owing to the transcriptional-translation feedback loop. Components of this loop do not affect just their own run, but they also have an impact on some other functions of the cell, for example cell cycle. This interaction is made by clock proteins (PER, CRY etc.) and by clock-controlled proteins (WEE1, TIM, XPA etc.). These proteins participate in the cell cycle run and have an impact on check-points. Disruption of the circadian clock can cause faults in cell cycle check-points, storing of DNA damages and increased cell apoptosis or tumor progression. Key words: circadian systém, cell cycle, WEE1, XPA, P21, C-Myc, TIM, PER
|
|
|
Circadian system of the retina
Kozel, Tomáš ; Bendová, Zdeňka (advisor) ; Moravcová, Simona (referee)
Most of the known living organisms have developed an evolutionary adaptation to a 24-hour daily rhythm. This rhythm, known as circadian rhythm, can be preserved even in the environment, in which there is no access to light or other synchronizer. The master organ of circadian rhythm is located in the hypothalamic suprachiasmatic nucleus (SCN) and have been considered the only autonomous circadian oscillator for a long time. The new research, however, has doubted this hypothesis by showing the existence of autonomous circadian clock systems independent of SCN. One of these autonomous clocks is the circadian system in the retina. This bachelor thesis reviews current scientific knowledge on the function of mammalian retinal circadian oscillator, most importantly in the field of its localization, connection with the SCN master circadian oscillator and its influence on retinal physiology.
|
|
|
Circadian system and memmory
Skálová, Kateřina ; Bendová, Zdeňka (advisor) ; Houdek, Pavel (referee)
Circadian system is a part of all living organisms. It controls suitable timing of their physiological functions and behaviour. The molecular mechanism of interlocking transcription-translational feedback loops of clock genes and their protein products forms the core of the circadian system. The main structures of this system in mammalian organisms are suprachiasmatic nuclei of the hypothalamus. Memory is also closely connected with circadian system. It is one of the most important abilities of organism for creating knowledge. Both memory and circadian system enable to the organism to adapt to changes in its external environment. The expression of clock genes was detected in brain structures involved in mediation of memory such as hippocampus, amygdale and basal ganglia. The oscillations of these clock genes influence the formation and retrieval of memory traces. The aim of this work is to summarize current knowledge about the relationship between the memory and the circadian system. Key words: circadian system, memory, clock genes, suprachiasmatic nuclei, hippocampus
|
|
|
Circadian principle of human chronotype
Ševčíková, Kateřina ; Bendová, Zdeňka (advisor) ; Šmotek, Michal (referee)
Circadian system is an oscillating system with approximately 24 hour period. In humans, it consists of suprachiasmatic nuclei and peripheral oscillators. Suprachiasmatic nuclei by means of external stimuli synchronize its endogenous period about the time of day. It is controlled by clock genes. The circadian system affects hormone levels, and with the homeostatic system is the major regulator of sleep. In these cyclic systems in humans, there are some differences that define human chronotype. This thesis is focused on the changes in the circadian system that underlie human chronotype. It deals with polymorphisms of clock genes, periods of the rhythms in the production of hormones such as melatonin and cortisol and their differences in distinct chronotypes. At the circadian chronotypes, there were also found differences in REM and REM sleep cycles and their amplitudes. Chronotype and circadian system are dependent on age and gender. Powered by TCPDF (www.tcpdf.org)
|
|
|
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)
|
|
|
Cirkadiánní systém a neuropsychiatrická onemocnění
Šuchmanová, Karolína ; Sumová, Alena (advisor) ; Červená, Kateřina (referee)
Neurodegenerative and psychiatric disorders are an important issue, affecting a great part of our population. Recently, awareness of sleep disturbances and circadian rhythm dysfunctions accompanying these diseases is growing. Although the cause of circadian clock malfunctions in neuropsychiatric disorders remains to be elucidated, they have a destructive impact on quality of life of both patients and their caregivers. Thanks to our knowledge on molecular mechanisms of the circadian clock and novel techniques, it becomes possible to study the state of the central pacemaker, as well as its' output rhythms. This thesis provides a summary of data suggesting an important role of circadian system malfunctions in patients suffering from neurodegenerative and psychiatric diseases. In some cases, these data also suggest new therapeutic approaches, which could in the future help to ameliorate the patients' quality of life, by improving the functioning of their circadian system. Key words: neuropsychiatric disease, circadian system, human, melatonin, clock gene
|
|
|
The effect of melatonin for sleep regulation in humans with autism
Spišská, Veronika ; Bendová, Zdeňka (advisor) ; Kopřivová, Jana (referee)
Autism is, mainly in children, accompanied by a variety of sleep and circadian disorders. These disorders may be partly caused by problems in the synthesis of melatonin. This work is interested in sleep and circadian problems of children with autism and their possible treatment with exogenous melatonin. The paper presents the symptoms of autism and its causes, the basic principles of circadian system, the regulation of melatonin synthesis and the characteristics of sleep. The last chapter describes the changes in melatonin synthesis and disturbances in the production of other hormones (serotonin, cortisol). Sleep and circadian disorders in autistic individuals and their impact on other symptoms of autism such as communication and socialization are also listed in the last chapter. There are also cases of the treatment of sleep disorders in autistic children with melatonin reported. Treatment with melatonin improves sleep disorders and has almost no side effects. Key words: autism, circadian system, melatonin, sleep
|
|
|
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...
|
|
|
Suprachiasmatic nuclei as a daily clock and calendar
Pačesová, Dominika ; Sumová, Alena (advisor) ; Hock, Miroslav (referee)
The suprachiasmatic nuclei (SCN) harbor the master circadian pacemaker in mammals which is responsible for control and coordination of circadian rhythms throughout the body. They are a paired structure in the hypothalamus, located just above the optic chiasm, consisting of approximately 20 000 neurons. Due to their specific properties, the SCN have a unique position within the circadian system. They are connected with retina and, therefore, they can directly receive information about changes in external light/dark cycle. The individual SCN neurons are independent autonomous circadian oscillators which are inter-connected in a communication network. This network allows the individual SCN oscillators to synchronize among each other and thus to increase the precision and robustness of the oscillations. This work is focused to summarize the knowledge on the structure and function of the SCN at the level of single cells, subpopulations of cells and the whole SCN. The specific goal of this work is a summary of the factors that determine their central role within the circadian system.
|
guest ::
