Search

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...

Circadian rhythmicity, which evolved in accordance with the rhythmicity of the external environment tied to the earth's rotation, governs the regular rhythms of our physiology and behavior. The central circadian clock in the suprachiasmatic nuclei of the hypothalamus controls the roughly 24-hour rhythmicity of many peripheral clocks of most cells of the body, that can be observed from the molecular to the behavioral level. The intrinsic circadian period (τ) in humans is on average slightly longer than 24 h, but may also be slightly shorter. Individuals with a short τ are referred to as morning chronotypes, whereas individuals with a long τ are referred to as evening chronotypes. However, the majority of the population belongs to the so-called intermediate chronotype. The molecular mechanism of circadian oscillations controlled by the circadian clock has been shown to be closely linked to cellular metabolism. Many physiological processes important for physical and cognitive performance are also regulated by the circadian system. The main aim of both studies was to quantify the difference in performance during morning and evening testing in subjects of a pronounced evening and morning chronotype. While the motivation for conducting Study A was practical, with the aim of identifying potential biases...

The circadian clock exists in every organism and their period is approximately 24 hours. This circadian rhythm is maintained even in a completely non-periodic environment but must be adapted to a precise 24-hour solar cycle using a synchronizer, called zeitgeber. The main controlling organ of the circadian rhythm are the suprachiasmatic nuclei (SCN) in the ventral hypothalamus. There are also peripheral clocks, for example in the liver or lungs. These peripheral clocks operate autonomously but the SCNs synchronize them with their own period and phase. The most important zeitgeber is the light and dark alternation. This bachelor thesis describes the consequences of conditions where there is no regular light and dark alternation and constant light conditions are established instead. Constant light can disturb the circadian rhythm and desynchronize the circadian clocks. This bachelor thesis summarizes the scientific knowledge of desynchronization by the effect of constant light and briefly describes the selected pathologies resulting from the desynchronization of the circadian system. Selected pathologies include ovarian tumour and breast cancer, obesity and insulin resistance, immunosenescense and schizophrenia. Key words constant light, circadian system, suprachiasmatic nucleus

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

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...