Vol 59, No 3 (2023)

In the course of evolution and adaptation to life conditions, organisms have developed the strategies that allow to use of the reactive oxygen species (ROS) in regulation of physiological processes and in maintenance of homeostasis. Retinal pigment epithelium (RPE) is one of the prime examples of tissues with a high level of metabolism and intracellular ROS, that have the more risk of damage after oxidative stress (OS), under the influence of exogenous or endogenous stress factors. Vertebrate RPE cells, despite the conservatism of the eye tissue structures and their main functions, respond differently to OS are due to the taхon-species specificity of the components of signaling pathways that form the antioxidant defense system (AODS). Transcription factors, in particular, Nrf2 play a key role in AODS. AODS in RPE includes the several levels of regulation, interaction of which ensures the stability of morphofunctional state of the cells. Phylogenetic analysis of the key components of AODS in various vertebrates revealed not only conservation, but also variability in the protein domain organization. This may reflect the differences in functions, adaptability and regenerative potential. The identification of AODS mechanisms that ensure the morphofunctional stability of RPE cells is of fundamental importance and is aimed at finding tissue-specific targets for effective treatment of a spectrum of eye diseases.

The in vitro effect of cold shock on erythrocytes of the benthic scorpionfish Scorpaena porcus L. was studied. The blood samples were exposed to 22°С (control group) and 4°С (experimental group) for 3 hours. Cold shock had no significant impact on erythrocyte scorpionfish vital function. The cells maintained the integrity of cytoplasmic membranes, mitochondrial potential and the level of oxidative processes, that the constant values of Propidium Iodide (PI), Rhodamine 123 (R123) and 2',7'-Dichlorodihydrofluorescein diacetate (DCF-DA) fluorescence levels demonstrated. Main changes referred to erythrocyte shape and nucleus functional activity. Cells gained more roundish shape, nucleus size increased with the growth of the nuclear-cytoplasmic ratio (NCR) and the decrease of fluorescence intensity of the cells labeled with SYBR Green I. It appears to be related to the activation of transcriptomic processes.

The transmural sequence of depolarization of the free walls of the ventricles of the heart of Wistar rats was studied with an increase in the heart rate under zoletyl- xylazine anesthesia. The increase in heart rate was caused by atrial electrical stimulation. Zoletyl-xylazine anesthesia with intramuscular injection at a dose of 0.15 mg/kg of zoletil and 3 mg/kg of xylazine caused a significant negative chronotropic effect with pronounced bradycardia, characterized by a decrease in heart rate from the initial two times. With a reduced sinoatrial rhythm with a frequency of 237 ± 34 beats/min, the subendocardial layers were initially depolarized, then the intramural and further subepicardial layers of the left and right free walls of the ventricles of the heart. The areas of the bases of the free walls of the ventricles depolarized later than the apical areas by approximately 2–4 ms, also by the movement of the activation wave from the endocardium to the epicardium. With an increase in heart rate, the sequence and transmural depolarization gradient did not change. At the same time, an increase in the stimulation frequency from 300 to 500 beats/min led to a decrease in the time of arrival of the depolarization wave to the subendocardial, intramural, and subepicardial layers of the walls of the left and right ventricles. Despite the depressive effect of zoletyl-xylazine anesthesia on the heart and its chronotropic function, at a high frequency of atrial electrical stimulation, the depolarization gradient from the endocardium to the epicardium and from the apex to the base of the ventricles was preserved, there were only minor changes in the duration of the process of transmural depolarization of the walls of the ventricles of the heart. This indicates the resistance of activation of the ventricles of the heart of Wistar rats to the toxic effect of zoletyl-xylazine anesthesia.

Hippocampal theta oscillations are pivotal for hippocampal functions of spatial navigation, learning and memory. In the behaving animals in vivo, hippocampal theta oscillations display bilateral synchronization. Internally generated oscillations in the theta frequency range have also been described in the intact hippocampus preparation in vitro. How theta oscillations are synchronized between the left and right hippocampi remains elusive, however. We used preparation of the intact hippocampi interconnected by the ventral hippocampal commissure prepared from juvenile and adult mice and rats in vitro. Local field potentials and multiunit activity were recorded using extracellular electrodes from the pyramidal cell layer and stratum radiatum of the left and right hippocampi. Neuronal network activity in the left and right hippocampi was organized in theta oscillations, which strongly modulated neuronal firing of CA1 neurons. Both neuronal activity and field potential theta oscillations showed high levels of bilateral synchronization. Theta oscillations persisted on both sides, but their bilateral synchronization was eliminated after surgical cut of the ventral hippocampal commissure. Thus, theta oscillations are synchronized in the left and right hippocampi in vitro, and their bilateral synchronization is provided by the ventral commissural connections.

The effects of light deprivation on age-related changes in body weight, food and water intake, as well as the activity of digestive enzymes in pancreatic tissues of male rats was studied. Animals were divided into three groups: the first was in standard light conditions (12 h light/12 h dark, control, LD), the second was kept under conditions of long-term light deprivation from the moment of birth (LD/DD), and the third – from the prenatal period (DD/DD). Prolonged keeping of rats under conditions of light deprivation led to disruption of the age-associated dynamics of the studied parameters, at the same time, the detected changes in response to a specific light condition differed depending on the stage of ontogenesis at which its exposure began. Thus, body mass (age 3 and 18 months) and food and water intake (12 months), amylase and lipase activities (18 months) were lower, and protease activities after the end of the stable growth stage (12, 18 and 24 months) were higher in LD/DD-rats than in LD-rats. Significant changes in the studied parameters were observed under DD/DD conditions in 12‑month-old and 18-month-old rats – body mass was the largest, and food and water intake were the lowest compared to LD and LD/DD. In addition, the maximum amylase activity (1 and 6 months) among the studied groups and the higher values of total proteolytic activity during the period of stable growth (6 and 12 months) were found in DD/DD-rats compared to controls. Thus, our results indicate that light deprivation disrupts the ontogenetic development program of the digestive system of mammals.