Clinical course of pro-oxidant processes in brain structures in rats under conditions of experimental hyperthyroxinemia in age-related dynamics

Abstract

The search for a connection between changes in the indicators of the pro-oxidant system of brain structures and the thyroid gland as a target organ is an urgent issue. The goal is to investigate the features of the pro-oxidant system against the background of experimental hyperthyroxinemia and to evaluate the age-related changes of malondialdehyde and diene conjugates in brain structures. Among Wistar rats (n=50) intact animals ("control", Σ=20) and experimental animals (under simulated hyperthyroxinemia, Σ=30) were selected for observation. The principle of the model of experimental hyperthyroxinemia lies in the addition of levothyroxine in a dosage of 20 μg/day (manufactured by "Berlin-Chemie AG", Germany) in the form of tablets with subsequent grinding at 9 o'clock in the morning with food. On day 14, hyperthyroxinemia in the animals was found, while the thyroxine level in the peripheral blood was >10 μg/dL in the first 48 hours and further, being >25 μg/dL (the results were verified in the laboratory, confirmed by immunoenzymatic method with the participation of the "Humarlander" test system). After functional testing in rats, highly specific parameters (malondialdehyde, diene conjugates) in the cortex, trunk, and hippocampus were further recorded and evaluated. The humane treatment of animals is certified by the local protocol of the meeting of the commission of the Dnipro State Medical University No. 10 dated 21.06.2023, bioethical principles and rules are taken into account during the experimental research. In the presented work, the results of the biochemical method were used to discuss the importance of the pro-oxidant system at the stage of protection against manifestations of stress and anxiety. Functional dependence on the accumulation of intermediate and final products of lipid peroxidation in the structures of the brain during the study of the state of the pro-oxidant system was found; the age-related dynamics of the activity of malondialdehyde and diene conjugates from young to middle-aged rats under conditions of experimental hyperthyroxinemia was observed; age-related changes contribute to a certain depletion of the activity of pro-oxidant compounds in response to stress as a principle of nervous system protection.