Work

State of the protective systems of rats during the development of experimental toxocariasis

Year: 2025

Type: article

Abstract: An important pathogenetic link of toxocariasis is the imbalance between the formation of reactive oxygen species and the capacity of the antioxidant system, which leads to intensification of lipid peroxidation, damage to biomembranes, and a decrease in the efficiency of membrane-bound enzymatic systems. In addition, parasitic invasion may cause suppression of humoral and cellular mechanisms of natural resistance and the development of an immunodeficiency state. The aim of the study was to comprehensively assess changes in the antioxidant defense system and the immune system of white rats during the development of experimental toxocariasis, in particular to determine the intensity of lipid peroxidation, the activity of enzymatic and non-enzymatic components of the antioxidant system, as well as the state of humoral and cellular mechanisms of natural resistance of the organism. The study was conducted on 20 sexually mature male white rats (150–180 g) kept under standard vivarium conditions and fed a balanced diet. The animals were divided into control and experimental groups (n = 10). Rats of the experimental group were infected with invasive Toxocara canis eggs at a dose of 30 eggs per 1 g of body weight by oral administration in a 2 % starch gel. The intensity of lipid peroxidation was assessed by the levels of lipid hydroperoxides and thiobarbituric acid–reactive substances (TBARS). The state of the antioxidant system was evaluated by measuring the activity of superoxide dismutase, catalase, glutathione peroxidase, and the content of reduced glutathione. Immunological status was assessed by determining serum bactericidal and lysozyme activities, the level of circulating immune complexes, as well as neutrophil phagocytic activity and the phagocytic index. Statistical analysis was performed using methods of variation statistics; differences were considered significant at P < 0.05. It was found that under conditions of experimental toxocariasis, oxidative stress develops in rats, manifested by a significant enhancement of lipid peroxidation processes: the level of lipid hydroperoxides increased by 74.8 % (P < 0.001), and TBARS increased by 23.4 % (P < 0.01) compared with the control group. Against the background of lipid peroxidation activation, suppression of antioxidant defense was observed: superoxide dismutase activity decreased by 20.9 % (P < 0.001), catalase activity by 33.2 % (P < 0.01), and glutathione peroxidase activity compared with the control; the content of reduced glutathione decreased to 1.98 ± 0.02 mM/L versus 2.72 ± 0.01 mM/L in control animals (P < 0.001). These data indicate depletion of both enzymatic and non-enzymatic components of the antioxidant system. Evaluation of nonspecific resistance parameters revealed the development of immunodeficient changes in infected rats. Serum bactericidal activity decreased by 6.22 % (P < 0.01), and lysozyme activity by 5.07 % (P < 0.05), reflecting weakening of humoral factors of innate immunity. At the same time, a significant increase in circulating immune complexes up to 70.38 ± 3.81 mmol/L (P < 0.01–0.001) was recorded, which is a marker of immune response tension and the immune-complex component of inflammation. Regarding cellular mechanisms of nonspecific defense, suppression of phagocytosis was observed: neutrophil phagocytic activity decreased (P < 0.01), and the phagocytic index decreased by 29.9 % (P < 0.01). Thus, experimental toxocariasis in rats is accompanied by complex disturbances of the organism’s protective systems, including the development of oxidative stress with intensified lipid peroxidation and suppression of the antioxidant system, as well as a decrease in natural resistance and weakening of humoral and cellular mechanisms of nonspecific immune defense. The obtained results deepen the understanding of toxocariasis pathogenesis and may be used to assess the severity of invasion and to substantiate approaches to immunometabolic correction in parasitic diseases.

Source: Ukrainian Journal of Veterinary and Agricultural Sciences

DOI: 10.32718/ujvas8-3.12

Authors: I. V. Tokar, V. V. Stybel, B. V. Gutyj

Institutions: Stepan Gzhytskyi National University of Veterinary Medicine and Biotechnologies Lviv, SCIVP of Veterinary Medicinal Products and Feed Additives

Language: English

Topic: Parasites and Host Interactions

Subfield: Parasitology

Field: Immunology and Microbiology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: diamond

Funder: Ministry of Education and Science of Ukraine