DYNAMICS OF ANTIOXIDANT ENZYME ACTIVITY AND REDUCED GLUTATHIONE LEVEL IN SUPERFICIAL CERVICAL LYMPH NODES OF RATS UNDER CONDITIONS OF INDUCED COLORECTAL CARCINOGENESIS

Abstract

Introduction. Colorectal cancer is one of the most common malignant neoplasms worldwide. The pathogenesis of the neoplastic process is characterized by disturbances in cellular redox homeostasis, accompanied by excessive reactive oxygen species production and oxidative stress. The cellular antioxidant defense system plays a key role in maintaining redox balance and protecting cells from oxidative damage. However, changes in the antioxidant system in immune organs distant from the primary tumor site remain insufficiently studied. Therefore, investigation of antioxidant parameters in superficial cervical lymph nodes may contribute to a deeper understanding of systemic responses to tumor development. The study aimed to investigate the dynamics of antioxidant enzyme activity (SOD, CAT, GPx, GR) and reduced glutathione (GSH) levels in superficial cervical lymph nodes of white rats under conditions of induced colorectal carcinogenesis. Methods. The study was performed on 98 white male outbred rats. The animals were divided into groups: I – intact animals; II – animals in which colorectal cancer was induced by injections of N,N-dimethylhydrazine hydrochloride. The induction period lasted 210 days, and the animals were euthanized every 30 days to monitor the dynamics of changes (7 time points). Enzyme activities and GSH levels in lymph node homogenates were determined spectrophotometrically using standard methods. Statistical analysis was performed using the independent two-sample Student’s t-test and one-way analysis of variance (ANOVA) with Tukey’s post hoc test. Results and discussion. Under conditions of N,N-dimethylhydrazine-induced colorectal carcinogenesis, an increase in antioxidant system parameters was observed in superficial cervical lymph nodes at early stages (days 30–90) compared to intact animals: SOD activity increased by up to 9,22 %, CAT by up to 14,02 % (p<0,05), GPx showed a moderate increase, and GSH levels were also elevated. At later stages (days 180–210), a decrease in antioxidant parameters relative to control values was detected: by day 210, SOD activity decreased by 5,53 %, CAT by 17,09 % (p<0,05), GPx by 13,33 % (p<0,05), and GSH levels by 12,14 % (p<0,05). Meanwhile, GR activity showed a decreasing trend but was not statistically significant. Conclusions. A biphasic pattern of changes in the antioxidant system was established, characterized by an initial compensatory activation followed by progressive depletion. These findings indicate impairment of antioxidant defense in lymphoid tissue during the development of the neoplastic process.