| Popis: |
The circadian system temporally controls behavioral and physiological processes in most organisms so that they change during the day and night with a period of about 24 h. It is an evolutionary adaptation to anticipate periodic changes in environment on the Earth. In mammals, the circadian system consists of the central pacemaker in the suprachiasmatic nuclei (SCN) of hypothalamus and of oscillators located in numerous peripheral organs and tissues. At the molecular level, the circadian clock is based on the rhythmic expression of so called clock genes. The ontogenetic development of the circadian system is a gradual process and the most important changes undergo during the late embryonic and early postnatal stage. Many behavioral, hormonal and metabolic signals provided by the mother are considered to be involved in circadian clock synchronization during early ontogenesis. The mechanisms of the entrainment are not fully known yet. The aim of this thesis was to study the development of the circadian clock and its entrainment via maternal signals and to compare the development of circadian rhythms in two model rat strains - Wistar rat and spontaneously hypertensive rat (SHR). Firstly, we described the ontogenetic maturation of the Wistar rat circadian clock in the colon from the fetal stage until... |
