Effects of Testosterone Undecanoate Treatment on Some Oxidative Stress and Histopathological Parameters in Testicular Tissue of Rabbits

Abstract

Background: Studies on Anabolic androgenic steroids (AASs), which are increasingly used by many people, such as professional athletes, bodybuilders, in an uncontrolled manner with each passing day, have indicated that they can cause oxidative stress besides many side effects. The aim of the present study is to investigate the effects of testosterone undecanoate (TU), an anabolic steroid, on histopathological and oxidative stress in testicular tissues of New Zealand rabbits.
Materials, Methods & Results: The study was conducted on 18 male New Zealand rabbits aged 5-6 weeks. The study involved three groups: the control group, the castor oil group, and the TU group, each of which included six New Zealand rabbits. While no treatment was provided to the control group, 0.2 mL castor oil was injected intramuscularly (IM) into the castor oil group and 0.2 mL TU (10 mg/kg) dissolved in castor oil was injected IM into the TU group for 6 weeks, 5 days a week. At the end of the experiment, testicular tissue samples of the animals that were euthanized under appropriate conditions were collected, and histopathological examinations and oxidative stress parameters in testicular tissue were analyzed. In the study, superoxide dismutases (SOD), glutathione (GSH), glutathione peroxidase (GPx) and catalase levels of testicular tissue in the TU injected group showed a statistically significant decrease compared to the control group (P < 0.05). When the macroscopic appearance of the testes was examined, it was found that the testes in the control and castor oil groups were macroscopically similar to each other, while the testes of the rabbits in the TU group appeared atrophic. When the mean Johnsen scores calculated in all groups were evaluated, it was observed that the control and castor oil groups were normal, while the TU group was thought to have maturation arrest. As a result of the histopathological examinations, the testicular tissue sections of the control group showed that the seminiferous tubules were regular and normal in diameter and size. When the testicular tissue sections of the castor oil group were examined, seminiferous tubules were found to be in good condition. The microscopic examination of the testicular tissues of the TU group showed atrophic changes in most of the seminiferous tubules. Besides the shrinkage in the size of these atrophic tubules, it was remarkable that the normal structure was disrupted and the cells were separated from the basal membrane and exfoliated into the lumen. Consequently, based on the findings that TU triggered oxidative stress in the testicular tissue of New Zealand rabbits and showed macroscopically and histopathologically adverse effects, it was concluded that the use of such AASs may cause significant health problems, and their use should be controlled.

Discussion: Increased production of free radicals and weakening of the antioxidant defense system can lead to oxidative stress, which results in arterial blockages, severe damage to cells, and consequently impaired spermatogenesis. If the testicular biological system fails to detoxify or repair the negative effects of free radicals, cells and tissues are severely damaged. Long-term nandrolone decanoate (a testosterone preparation) treatment has been reported to decrease kidney tissue GSH and testicular tissue SOD levels in rats and New Zealand rabbits. Similarly, injection of boldenone undecylenate, an AAS, was noted to significantly reduce SOD, GSH, and catalase levels in the testicular tissue of rats, an indicator of oxidative stress in rat testes. The present study showed a statistically significant decrease (P < 0.05) in testicular tissue SOD, GSH, GPx, and catalase levels in the group to which TU was injected and this finding was consistent with the findings of previous studies.
Keywords: rabbit, testosterone undecanoate, testis, oxidative stress.