The Level of Reactive Carbonyl Derivatives of Proteins, Methylglyoxal, and Malondialdehyde in Rats Experiencing Chronic Unpredictable Moderate Stress

Abstract

BACKGROUND: Prolonged exposure to stress is known to change homeostasis and can lead to the development of psychopathological disorders, including depression. Exposure to stress factors contributes to the emergence of reactive oxygen species in the brain. The data characterizing changes of the oxidative metabolism under conditions of chronic stress are insufficient, which determine the relevance of the research in this direction. The determination of reactive carbonyl derivatives of proteins (RCDP), methylglyoxal (MG), and malondialdehyde (MDA) levels can be considered an informative method for studying the dynamics of oxidative metabolism.
 AIM: The aim of the study was to study the RCDP, MG, and MDA in red blood cells and blood plasma in rats experiencing chronic unpredictable moderate stress (CUMS).
 METHODS: A total of 20 male outbred rats weighing 450–500 g were used in the study. The animals were divided into two groups of ten rats each using randomized selection. The experimental group of animals was exposed to the impact of diverse stress factors, according to the CUMS model for 21 days. The control group of animals remained in standard conditions and did not undergo CUMS model. Blood sampling was performed twice for all rats the day before the experiment started and on 21st day to determine the level of RCDP, MG, and MDA in their erythrocytes and blood plasma.
 RESULTS: The study revealed a significant decrease of RCDP (p = 0.007) and MDA levels in erythrocytes (p = 0.013), and MDA level in blood plasma (p = 0.005) of rats of the main experimental group. The control group showed a significant increase of RCDP level in plasma (p = 0.008), a two-fold increase of MDA in erythrocytes (p = 0.05) with a decrease of MDA in plasma (p = 0.011). A tendency for MG increase was noted in erythrocytes of rats in both the main group and the control group.
 CONCLUSION: The early stages of CUMS were accompanied by the violation of oxidative metabolism with the emergence and accumulation of RCDP and MDA in the blood of animals. The decreased emergence of RCDP and MDA in the later stages can be associated with an excess of oxidized substrates in the blood of animals of the experimental group. The revealed trend toward MG growth in animals of both groups suggests its increased synthesis in erythrocytes, which, in our opinion, should be considered a negative factor affecting the deformability of red cells. In turn, a violation of the deformability of red blood cells leads to a violation of microcapillary blood flow, which contributes to the development of hypoxic damage in different tissues. Thus, the obtained data confirm the different directions of changes in RCDP and MDA levels in the blood of animals experiencing CUMS or acute stress. Our results prove the need for further research on changes in oxidative metabolism in chronic stress disorders.