The activity of superoxide dismutase and catalase was increased, but the activity of superoxide dismutase was increased almost 2 times than the activity of catalase. The purpose of the work was to study biochemical changes in the testicles of rats in chronic long-term hypomelatoninemia. Material and methods of research. To perform the tasks, we conducted experiments in vivo on male rats of the Wistar line weighing 180-190 g. The standard norm was 6 intact animals. In the second experimental group, 6 rats reproduced hypomelatoninemia: animals of 55 days, compared with the term spermatogenesis in rats (48 days), were kept at round-the-clock light, and on the last day they were not allowed to sleep. Euthanasia was performed under hexenal anesthesia by selecting blood from the ventricle of the heart. Animals were kept in conditions fixed in the "Standard Rules for Organizing, Equipment and Maintenance of Experimental Biological Clinics (vivarium)". When working with laboratory animals, they adhered to the rules of bioethics, moral and ethical norms described in the conclusion of the commissions (Minutes № 31, September 26, 2005). The retention of rats was consistent with the standards of typical vivarium and was based on relevant documents. Results and discussion. Due to the fact that superoxide dismutase is the major producer of H2O2 in the cells, we supposed some increasing in the concentration of H2O2 as prooxidant agent. Some researchers say that there is mitochondrial and microsomal electron-transport chain oxidation and respiratory burst of phagocytes in the testicles of the leading producers of the superoxide anion radical (output active form of oxygen). This reaction gives 8-22 times less superoxide. Conclusions. The influence of stress, inflammation, gamma irradiation, aging cause the imbalance in generating reactive oxygen species, increases the proportion of the respiratory burst damaging the cell membrane, and leads to necrosis. Intracellular generators influence on the DNA, but here comes a possible protective mechanism of melatonin as an antioxidant. At the same time, increasing of peroxidation may inhibit cell division and cause mutagenic DNA damage (demethylation of 5-methylcytosine, forming of 8-oxoguanine).
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