FUNCTIONAL STATUS OF KIDNEYS AND OXIDATIVE STRESS LEVEL IN RATS UNDER CONDITIONS OF DEPRESSION AND DIETARY CAFFEINE LOAD

The level of oxidative stress and functional parameters in rat kidney homogenate under depressive conditions and additional alimentary caffeine load were determined. Depression was simulated by the method of chronic unpredictable stress for 5 weeks, contagious depression – in the same period.Kidney tissue samples were obtained by homogenisation and ultracentrifugation. Total protein and malondialdehyde levels were determined in blood plasma and kidneys. Creatinine and urea levels were determined in kidney samples. The concentration of total protein was determined by the biuret method. Malondialdehyde was determined by the total amount of TBA-active compounds. ANOVA followed by Tukey’s test was used to assess statistical differences between groups. Statistical data processing was performed using GraphPad Prism software, v 8.1.0. The results were considered reliable if p≤0.05. It is shown that under the conditions of both depressions modelled by chronic unpredictable stress and contagious depression, oxidative stress develops, which is expressed in increased levels of malondialdehyde, both in blood plasma and in kidney homogenate. Under conditions of caffeine use, the changes were more significant in females. A high level of creatinine compared to other animals was observed in a subgroup of males with contagious depression. The study of creatinine levels in a group of animals administered caffeine after simulating contagious depression showed a 15-25% decrease compared to depressed animals. The level of urea in the rat kidney homogenate decreases by 23% in depressed males after caffeine consumption, while in females, on the contrary, it increases by an average of 20% in both ways of modelling the depressive state. The increase in creatinine and urea in the caffeine group, regardless of the sex of the animals, indicates a decrease in kidney function and an additional burden on their filtration capacity under these conditions.