Influence of diabetes mellitus on free radical processes in the heart in rats with Guerin's carcinoma and characteristics of malignant lesions depending on the gender of animals

To study the intensity of lipid peroxidation (LPO) and the activity of the main antioxidant protection enzyme: superoxide dismutase (SOD) in heart tissues and tumors in rats of both genders with Guerin's carcinoma (GC) and the tumor growth against the background of diabetes mellitus (DM). Materials and methods. Our research work was carried out in 80 outbread albino male and female rats, divided into 4 groups, with 10 animals of each gender in a group. The animals of two groups, namely, an intact animal group and a group of rats treated with alloxan DM (with a 5-fold increase in glucose levels) were subcutaneously transplanted with the Guerin's carcinoma (GC) strain cells, and at the same time we used one group of the intact rats and another group of the animals with DM as the references. The content of malondialdehyde (MDA), diene conjugates (DC), and the SOD activity in the heart and the tumor tissues were determined by conventional spectrophotometric methods. Results. The most pronounced changes were found in the heart in the female rats with isolated GC and GC growing against the background of DM: a more than threefold increase in MDA, with a significant increase in DC and a multiple increase in the SOD activity as compared with the intact animals. In the GC tissue, the dependence of the severity of the increase in the MDA content on the size of the tumor was traced: the maximum increase in both parameters was observed in males with GC tumor growing against the background of DM. In the males, the volume of the subcutaneous tumor nodes was 1.8 times greater than that in the reference group and in the females with combined pathology, while in the females with combined pathology the volume of their tumors was 1.3 times less than that in the reference group, although the area of tumor lesions in them was maximum due to extensive metastasizing. Conclusion. DM has changed the specifics of oncogenesis depending on the gender of the animals. The identified gender differences in the redox status of the heart and the tumor in rats with combined pathology contribute to specifics of oncogenesis in males and females and determines their life expectancy.