Thymoquinone is a protective agent that reduces the negative effects of doxorubicin in rat testis.

Background: Doxorubicin (DOX) is used for treatment of many cancer types. Thymoquinone (THQ) is a powerful antioxidant agent used for reducing side effects of several drugs. The aim of this study is to determine possible therapeutic effects of THQ on doxorubicin-induced testicular toxicity in rats. Methods: Rats were divided into five groups (n = 8): control, THQ, olive oil, DOX (a single dose of 15 mg/kg intraperitoneally (i.p.) on seventh day of the experiment), and DOX + THQ (10 mg/kg THQ per day and 15 mg/kg DOX i.p. on seventh day). Animals were euthanized, and testis tissues were evaluated histopathologically. Caspase 3 and HSP90 immunostaining were performed to determine the expression levels of these proteins among groups. Terminal deoxynucleotidyl transferase 2 '-deoxyuridine, 5 '-triphosphate nick-end labeling method was used for evaluation of apoptotic index. Moreover, serum testosterone levels and total antioxidant status (TAS) and total oxidant status (TOS) in testicular tissue were measured by ELISA assay. Results: The DOX group had histopathological deterioration compared to the control group. There was an increase in apoptotic index, caspase 3 and HSP90 expressions in the DOX group. While TAS level of the DOX group decreased, TOS level increased when compared with the other groups. Serum testosterone levels in the DOX group decreased compared to the control group. However, there was improvement in testicular tissue in DOX + THQ group compared to the DOX group. There was a decrease in apoptotic index, caspase 3, and HSP90 expressions in DOX + THQ group compared to the DOX group. Testosterone level of DOX + THQ significantly increased compared to the DOX group. Conclusion: We suggest that THQ can be used as a protective agent to reduce the toxic effects of DOX.