Volume 109, Nº 7 (2023)

Single fluorophore genetically encoded calcium indicators (GECIs) such as GCaMP are widely utilized tools for investigating neuronal activity. Their primary advantage lies in their capacity to provide real-time and highly sensitive responses to fluctuations in intracellular calcium ion concentrations. This characteristic is of significant importance when studying neuronal processes and ensembles, wherein calcium signals play a crucial role in information transmission. This comprehensive review focuses on the GCaMP family, encompassing an analysis of their various types, distinctive features, and potential applications for visualizing neuronal activity. Special attention is dedicated to the ongoing advancements in GCaMP technology, particularly the endeavors to expand their spectral properties and enhance their capability to detect high-frequency spike activity.

Different stressors, affecting the cells of target organs, can lead to genomic instability and even disintegration, which can play a role in the formation of post-stress pathologies. We studied the effect of psycho-emotional stressors (immobilization and mouse stress pheromone – 2,5-dimethylpyrazine) on the DNA integrity of hippocampal and bone marrow cell in male mice of CD1, CBA and C3H strains. Cytogenetic and immunocytochemical methods (alkaline comet assay, ana-telophase analysis of mitotic disturbances and analysis of γH2AX foci) were used. It is shown that the classic mouse stressor (immobilization or restraint), similar as 2,5-dimethylpyrazine, damages the genome of the cells of both organs studied. The destabilization of the cell genome of various organs is considered as an essential stage in the development of a stress response, which is an attempt of the organism to adapt to extreme environmental influences.

Dysfunction of skeletal muscles and their atrophy during unloading are accompanied by excess calcium accumulation in the myoplasm of muscle fibers. We hypothesized that calcium accumulation may occur, among other reasons, due to inhibition of SERCA activity under muscle unloading. In this case, the use of a SERCA activator will reduce the calcium level in the myoplasm and prevent the consequences of unloading. Male Wistar rats were divided into 3 groups: vivarium control with placebo administration (C, n = 8), 7-day suspension group with placebo administration (7HS, n = 8) and 7-day suspension group with intraperitoneal administration of SERCA CDN1163 activator (50 mg/kg (7HS + CDN), n = 8). One m. soleus of each rat was frozen in liquid nitrogen, the second was tested for functional properties. In the 7HS group, increased soleus fatigue was found in the ex vivo test, a significant increase in mRNA and the number of fast muscle fibers, an increase in the level of calcium-dependent CaMK II phosphorylation and the level of tropomyosin oxidation, as well as a decrease in the content of mitochondrial DNA and protein. All these changes were prevented in the SERCA CDN1163 activator group. Conclusion: 7-day SERCA activator administration does not delay of soleus atrophy, but prevents the development of its fatigue, probably by preventing a decrease in the number of type I fibers and markers of mitochondrial biogenesis.

WAG/Rij rats are genetic model of absence epilepsy with comorbid depression. Pathologic phenotype in WAG/Rij rats was shown to be associated with reduced dopamine (DA) tone within the mesolimbic DAergic brain system. Previously, it was found that maternal methyl-enriched diet (MED) in the perinatal period increases DA content in the mesolimbic DAergic brain system and reduces absence seizures and comorbid depression in adult offspring of WAG/Rij rats. Ventral tegmental area (VTA), containing DA cells bodies, is a main source of the mesolimbic DA synthesis. The aim of this study was to test the hypothesis that increases in the mesolimbic DAergic tone induced by maternal MED in offspring may be due to an increase in the number of DA-synthesizing neurons in the VTA. Immunohistochemistry for thyrosine hydroxylase (TH) was used to assess the number of TH-immunopositive cells in adult offspring of WAG/Rij rats born to mothers fed control diet or MED and subjected or not subjected to behavioral testing for 2 consecutive days in the light-dark choice, open field, elevated plus maze and forced swimming tests. One hour after the forced swimming test animals were anesthetized. Brains were fixed using transcardial perfusion. The number of DAergic neurons was determined by the number of TH-immunopositive cells on brain slices at the level of VTA. The number of TH-immunopositive cells was counted in left and right hemispheres separately. A significant effect of maternal MED on the number of cells in the VTA expressing TH has been established. Adult WAG/Rij offspring born to mothers fed MED had an increased number of TH-immunopositive cells as compared with the offspring born to mothers fed control diet. Moreover, in WAG/Rij offspring born to mothers fed MED, the number of TH-immunopositive cells was greater in animals subjected to behavioral testing compared with animals not subjected to behavioral testing. The effects of maternal MED and behavioral testing on the number of TH-immunopositive cells in the VTA were equally expressed in the left and right hemispheres of the brain. Results suggest that maternal MED in the perinatal period can affect the developing mesolimbic DAergic brain system, promoting the generation and/or maintenance of DA neurons in the VTA, and thereby prevent the occurrence of genetic absence epilepsy and comorbid depression in the offspring of WAG/Rij rats.

It is widely known that neuroinflammation is a key factor in the development of many neurological pathologies and neurodegenerative diseases. The dynamics of development and duration of neuroinflammatory responses are critical aspects in understanding the patterns of physiological, biochemical and behavioral consequences. The most common object of study is neuroinflammation that develops after experimental systemic inflammation. The effect of acute systemic inflammation on brain microgliocytes has been studied extensively, while spinal cord microglia have been studied less frequently. The purpose of this study was to assess the topographic and temporal features of morphofunctional changes in rat spinal cord microglial cells after experimental LPS-induced systemic inflammation. It has been established that in the early stages of neuroinflammation (24 hours after LPS administration), microgliocytes are activated in the ventral white and ventral gray matter of the spinal cord. At the same time, microgliocytes of the dorsal part of the spinal cord do not show morphological attribute of activation. An increase in the population density of microgliocytes in the ventral funiculus of the spinal cord was noted. Accumulations (aggregates) of reactive microgliocytes were also found in this area.

The study is aimed at assessing individual and age-related features of the functional state of various parts of the brain and the patterns of their ontogenetic changes based on the structural analysis of resting-state electroencephalogram (EEG) patterns in 5- to 7-year-old children. The study involved 266 children, who were divided into different age groups: Group 1–5 years old (mean age 4.98 ± 0.33), Group 2–6 years old (mean age 6.03 ± 0.35), and Group 3–7 years old (mean age 6.85 ± 0.22). Alpha-rhythm parameters recorded mainly in the occipital areas may serve as an indicator for the functional maturation of the brain. Significant age-related changes in the alpha-rhythm parameters have been revealed. The presence of a regular alpha-rhythm with a frequency of 8 to 10 Hz increases from 5 to 7 years of age. The occurrence of the alpha-rhythm of reduced frequency significantly decreases by the age of 7 years, and the occurrence of the polyrhythmic alpha-rhythm – by the age of 6 years. These changes are caused both by complications of the structural and functional organization of the cerebral cortex at the cellular level, which occur throughout the studied age period, and the improvement of its relationships with subcortical structures. A decrease in the occurrence of high-amplitude alpha-range electrical activity (EA) with signs of hypersynchrony in the caudal regions may indicate the maturation of the system of nonspecific activation of the brainstem reticular formation from 5 to 7 years of age. Age dynamics is also manifested in a significant decrease in the EEG occurrence of theta-range EA, and its zonal distribution in 5- to 7-year-old children aged. Such changes specify the process of progressive formation of functional connections between individual areas of the cortex, as well as the cortex and subcortical structures, in particular thalamo-cortical ones. The occurrence of alpha-range EA (less than 5.0%) and beta-range EA (about 13.0%) arranged topographically in the anterior cortex did not differ significantly with age. However, generalized EEG activity in the form of different frequency range waves, which characterizes the functional state of predominantly hypothalamic structures, occurs reliably more often in 7-year-old children rather than in 5-year-old children. Such dynamics is presumably associated with an increased reactivity of the hypothalamic-pituitary system in response to adaptive stresses caused by the transition to systematic learning and can be considered as a distinctive feature of this age period. Due to great restructuring of the brain functioning, all its structures become especially sensitive to high intellectual and emotional stress, which is characteristic of preschool children nowadays. The novelty of this study is highlighted by the identification of patterns, structure and nature of EA changes in 5- to 7-year-old normotypical children’s brain to assess the functional state of the cortex and regulatory brain systems. The research results based on a large sample of children, growing up in modern social and cultural conditions, would provide guidance for the formation of age standards.

The changes in the number of erythrocytes in the blood and the production of erythrocytes by the hematopoietic tissue of the golden grey mullet (Chelon auratus Risso, 1810) during the annual cycle were studied. Catching and delivery of fish to the aquarium was carried out monthly. The content of immature erythroid forms was determined: erythroblasts, basophilic and polychromatophilic normoblasts, in the head kidney (pronephros) and circulating blood. It has been established that the processes of erythropoiesis in the hematopoietic tissue of the golden grey mullet proceed irregularly. The active production of erythroid mass is mainly confined to the post-spawning period. This is evidenced by an increase in the content of immature erythroid forms in the head kidney and blood. This coincides with a general increase in the number of red blood cells in the circulation system and indicates a shift in the erythrocyte balance in favor of production processes. In the rest of the time, the processes are opposite. It is assumed that this is due to the peculiarities of the organization of the red blood system, which excludes the regular production of erythropoietin in the kidneys.