Sleep and Covid-19: neurophysiological and biochemical issues

Functional disorders of the nervous system against the background of Covid-19 are reviewed with the emphasis on sleep and circadian clock disorders during the pandemic. The pandemic is regarded as the strong stress factor that affects sleep and the clock. A large risk group consists of elderly people and people with concomitant somatic pathology. Data on the effect of SARS-CoV-2 on other organs and systems, on the functioning of the immune system, are presented.

Peculiarities of the ultrastructure of neurons of the neocortex of 5-day-day rats under conditions of prenatal alcoholization

The aim of this work was to study the ultrastructure of the internal pyramidal neurons of the neocortex of 5-day-old rat pups after antenatal alcoholization. The studies were carried out on female outbred white rats with an initial weight of 230 ± 20 g and their offspring. Prenatal alcoholization causes deep and varied ultrastructural changes in pyramidal neurons in the neocortex of 5-day-old rats. Moreover, these violations of direct action not only as a consequence of the damaging effect of alcohol, its metabolite acetehyde or the oxidative stress they cause on the membranes and organelles of neurons during embryogenesis, but also as a violation of the normal "program" of development" of neurons in the cortex.

Circadian clock precision, health, and longevity

An accurate circadian clock, associated with the precise intrinsic period, tau, can be linked with a definite chronotype and health status. Exemplified by different animal species, and, as we argue herein, may as well be in humans, endogenous tau close enough to 24 hours is associated with higher life expectancy, lower morbidity, and is possibly adhered to moderate morning chronotype. Accurate circadian tau facilitates maintaining a high amplitude of circadian rhythms, a phenotypic trait that is related to health and longevity. Some genetic factors that coordinate tau and ensure circadian clock precision is considered.

The effect of the intestinal microbiota and its metabolites on the central and peripheral circadian clock

The article describes the factors affecting the intestinal microbiota, which, in turn, lead to changes in the central and peripheral circadian clocks of the host. The role of the diet and the sleep-wake cycle on the intestinal microbiota, the relationship of nutrition and microbiota on gene expression are discussed, and the influence of microbial metabolites, short-chain fatty acids on the expression of clock genes are considered.

Development of the rat isocortex in antenatal and postnatal ontogenesis

This paper analyses and summarizes the literature data on the development of the rat isocortex in antenatal and postnatal ontogenesis. Information about the maturation periods of the isocortex neurons provides a fundamental basis for further studies of its development and the influence of various endogenous and exogenous factors on this process.