The circadian system controls the timing of behavioral and physiological functions in most organisms studied. The review addresses the question of when and how the molecular clockwork underlying circadian oscillations within the central circadian clock in the suprachiasmatic nuclei of the hypothalamus (SCN) and the peripheral circadian clocks develops during ontogenesis. The current model of the molecular clockwork is summarized. The central SCN clock is viewed as a complex structure composed of a web of mutually synchronized individual oscillators. The importance of development of both the intracellular molecular clockwork as well as intercellular coupling for development of the formal properties of the circadian SCN clock is also highlighted. Recently, data has accumulated to demonstrate that synchronized molecular oscillations in the central and peripheral clocks develop gradually during ontogenesis and development extends into postnatal period. Synchronized molecular oscillations develop earlier in the SCN than in the peripheral clocks. A hypothesis is suggested that the immature clocks might be first driven by external entraining cues, and therefore, serve as “slave” oscillators. During ontogenesis, the clocks may gradually develop a complete set of molecular interlocked oscillations, i.e., the molecular clockwork, and become self-sustained clocks., A. Sumová, Z. Bendová, M. Sládek, R. El-Hennamy, K. Matějů, L. Polidarová, S. Sosniyenko, H. Illnerová., and Obsahuje bibliografii a bibliografické odkazy
M4 muscarinic receptors (M4 MR) represent a subfamily of G-protein coupled receptors serving a substantial role in spontaneous locomotor activity regulation, cognition and modulation of cholinergic system. With increasing body of literature discussing the role of M4 MR some controversies arose. Thus, we try here to summarize the current evidence regarding the M4 MR, with the special focus on their role in locomotor activity control. We review the molecular function of M4 MR in specific brain areas implicated in locomotor regulation, and
shortly in other CNS processes that could be connected to locomotor activity. We also focus on brain areas implicated in locomotor activity biorhythm changes like suprachiasmatic nucleus, subparaventricular zone posterior hypothalamic area, striatum and thalamus. Gender-related aspects and differences in locomotor activity in males and females are discussed further.
The circadian rhythms of many behavioral and physiological functions are regulated by the major circadian pacemaker in the suprachiasmatic nucleus. Long-term opiate addiction and drug withdrawal may affect circad ian rhythmicity of various hormones or the sleep/activity pattern of many experimental subjects; however, limited research has been done on the long -term effects of sustained opiate administration on the intrinsic rhythmicity in the suprachiasmatic nucleus and pineal gland. Here we compared the effects of repeated daily treatment of rats with morphine or methadone and subsequent naloxone-precipitated withdrawal on the expression of the Per1, Per2, and Avp mRNAs in the suprachiasmatic nucleus and on arylalky lamine N-acetyltransferase activity in the pineal gland. We revealed that 10-day administration and withdrawal of both these drugs failed to affect clock genes and Avp expression in the SCN. Our results indicate that opioid-induced changes in behavioral a nd physiological rhythms originate in brain structures downstream of the suprachiasmatic nucleus regulatory output pathway. Furthermore, we observed that acute withdrawal from methadone markedly extended the period of high night AA -NAT activity in the pine al gland. This suggests that withdrawal from methadone, a widely used drug for the treatment of opioid dependence, may have stronger impact on melatonin synthesis than withdrawal from morphine., D. Pačesová, J. Novotný, Z. Bendová., and Obsahuje bibliografii