This study aimed to explore the radioprotective effect of melatonin against acute testicular injury caused by low- and high-dose-rate radiotherapy in rats. A total of 40 12-week-old adult male rats were divided into 5 groups (n = 8). Group 1 comprised control rats who were not subjected to any procedures. A single dose of 8 Gy (Gy) radiotherapy was administered to the abdominopelvic regions of Group 2 (low-dose rate radiotherapy (LDRR) group) and Group 4 (high-dose rate radiotherapy (HDRR) group) rats at dose rates of 400 MU/min and 1400 MU/min, respectively. A single dose of 8 Gy radiotherapy was administered to Group 3 (low-dose rate radiotherapy + melatonin (LDRR + MEL) group) and Group 5 (high-dose rate radiotherapy + melatonin (HDRR + MEL) group) rats at dose rates of 400 MU/min and 1400 MU/min, respectively. Following this, 50 mg/kg/intraperitoneal melatonin was given to the rats 15 min before radiotherapy. The subjects were sacrificed 48 h after radiotherapy. Histological, immunohistochemical, immunofluorescence, and biochemical analyses of testicular tissue samples were performed. As a result of comparing the FF and FFF radiotherapy groups with the control group, a statistically significant difference was observed in histopathological, biochemical, immunohistochemical and immunofluorescent parameters (p < 0.001). An improvement in these parameters was observed in the groups where melatonin was applied along with radiotherapy (p < 0.001). Additionally, no statistically significant difference was found between FF and FFF dose rates (p > 0.05). No significant difference was observed between these low- and high-dose rates of radiotherapy in terms of testicular damage and the effect of melatonin. Further, melatonin may be useful in preventing testicular damage caused by low- and high-dose rate radiotherapy.

中文翻译：

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褪黑素给药治疗低剂量率和高剂量率放射治疗引起的睾丸损伤：一项实验研究

本研究旨在探讨褪黑素对低剂量率和高剂量率放疗引起的大鼠急性睾丸损伤的放射防护作用。总共 40 只 12 周龄成年雄性大鼠分为 5 组（n = 8）。第 1 组包括未接受任何程序的对照大鼠。对第2组（低剂量率放疗（LDRR）组）和第4组（高剂量率放疗（HDRR）组）大鼠腹盆腔区域进行单剂量8戈瑞（Gy）放疗，剂量率为400分别为 MU/分钟和 1400 MU/分钟。对第3组（低剂量率放疗+褪黑素（LDRR+MEL）组）和第5组（高剂量率放疗+褪黑素（HDRR+MEL）组）大鼠进行单剂量8 Gy放疗，剂量率为分别为 400 MU/分钟和 1400 MU/分钟。此后，在放疗前15分钟给大鼠腹膜内注射褪黑素50mg/kg。放疗后48小时处死受试者。对睾丸组织样本进行组织学、免疫组织化学、免疫荧光和生化分析。将FF和FFF放疗组与对照组进行比较，在组织病理学、生化、免疫组化和免疫荧光参数方面观察到统计学显着差异（p < 0.001）。在使用褪黑激素和放疗的组中观察到这些参数有所改善（p < 0.001）。此外，FF 和 FFF 剂量率之间没有发现统计学上的显着差异 (p > 0.05)。在睾丸损伤和褪黑激素的作用方面，低剂量和高剂量放疗之间没有观察到显着差异。此外，褪黑激素可用于预防低剂量率和高剂量率放射治疗引起的睾丸损伤。