Ionizing radiation-induced testicular oxidative stress and apoptosis: the role of small GTPase RhoA

PURPOSE: The effects of ionizing radiation on living organisms are mainly known as the generation of reactive oxygen species (ROS), apoptosis, and DNA damage. Small GTPases (RhoA, Rac1, Cdc42) are known to have roles in the regulation of oxidative stress and apoptosis. The aim of this study was to investigate the role of the RhoA molecule in testicular tissue damage due to oxidative stress and apoptosis induced by ionizing radiation. MATERIAL AND METHOD: In this study, testicular tissues and blood samples obtained from our previous study were examined. In that study, rats were exposed to ionizing radiation at three different doses (0.02 Gy, 0.1 Gy, 5 Gy). Then tissue and blood samples were taken at three different times (2 hours, 24 hours, and 7 days) after irradiation. Immunohistochemical staining was performed to evaluate RhoA and cleaved caspase-3 expressions, while RhoA activity was assessed by G-LISA assay in testicular tissues. Serum malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity were analyzed to evaluate oxidative stress. RESULTS: The expression and activation of RhoA demonstrated a time-dependent increase across all levels of radiation doses. Similarly, the expression of cleaved caspase-3 also exhibited a time-dependent increase, consistent with the effects of radiation-induced damage observed in all experimental groups. After exposure to radiation, serum levels of MDA increased, while the activity of SOD decreased. CONCLUSION: Our findings suggest that RhoA may contribute to radiation-induced testicular tissue damage by increasing oxidative stress and apoptosis.