Sleep-wakefulness cycle and behavior in pannexin1 knockout mice.

Pannexins are membrane channel proteins that play a role in a number of critical biological processes (Panchin et al., 2000; Shestopalov, Panchin, 2008). Among other cellular functions, pannexin hemichannels serve as purine nucleoside conduits providing ATP efflux into the extracellular space (Dahl, 2015), where it is rapidly degraded to adenosine. Pannexin1 (Panx1) is abundantly expressed in the brain and has been shown to contribute to adenosine signaling in nervous system tissues (Prochnow et al., 2012). We hypothesized that pannexin1 may contribute to sleep-wake cycle regulation through extracellular adenosine, a well-established paracrine factor in slow wave sleep. To investigate this link, EEG and movement activity throughout the light/dark cycle were compared in Panx1-/- and Panx1+/+ mice. We found a significant increase in waking and a correspondent decrease in slow wave sleep percentages in the Panx1-/- animals. These changes were especially pronounced during the dark period. Furthermore, we found a significant increase in movement activity of Panx1-/- mice. These findings are consistent with the hypothesis that extracellular adenosine is relatively depleted in Panx1-/- animals due to the absence of the ATP-permeable hemichannels. At the same time, sleep rebound after a 6-h sleep deprivation remained unchanged in Panx1-/- mice as compared to the control animals. Behavioral tests revealed that Panx1-/- mice were significantly faster during their descent along the vertical pole but more sluggish during their run through the horizontal pole as compared to the control mice.

[Early Stages of Parkinson's Disease: Comparative Characteristics of Sleep-Wakefulness Cycle in Patients and Model Animals].

The results of study of sleep-wakefulness cycle in experimental models of pre-clinical and early clinical stages of Parkinson's disease present and compared to some clinical examples. The conclusion is, the increase in activity level and decrease in total amount of slow wave and paradoxical sleep in model animals are taking place at the same circadian period of the secretion of pineal melatonin as sleep disorders in patients.

[Dependence of Accuracy of Automatic Sleep Scoring on Spectral Characteristics of Mice EEG].

Computer programs for automatic sleep scoring of human and animals EEG records are widely used in many branches of physiological research. They are particularly useful during the sleep research because the traditional methods requiring human expert scoring of long records are very laborious and time-consuming. The aim of this work was to investigate the dependency of accuracy of automatic sleep scoring on different EEG parameters for EEG-recording quality assessment. We find statistically significant dependency of accuracy of automatic and expert scoring on several spectral characteristics. This dependency can be used as objective quality assessment method of EEG recording for sleep scoring and it makes possible to assess accuracy of automatic sleep scoring a priori.

The effect of hydrogen sulfide on electrical activity of rat atrial myocardium.

Changes in the configuration of action potentials and in the frequency of pacemaker discharges in a preparation of isolated rat right atrium under the effect of sodium hydrosulfide degrading in water solution with hydrogen sulfide release were studied by intracellular recording of action potentials in the myocardium. Sodium hydrosulfide in concentrations of 100-500 microM markedly reduced the duration of action potentials at the level of 50 and 90% repolarization and decelerated the sinus rhythm. Moreover, sodium hydrosulfide shortened action potentials in the preparations working in the forced rhythm. Glybenclamide (potassium ATP-dependent channel blocker; 10 microM) reduced the effect sodium hydrosulfide (200 microM) by more than 60%, which suggested the involvement of potassium ATP-dependent current in the realization of the effect of hydrogen sulfide on configuration of action potentials. Hence, hydrogen sulfide, recently described as a signal compound, modulates many electrophysiological parameters of the myocardium.