The place of tenacin c biomarker in the early detection of radiation-induced cardiotoxicity and the evaluation of melatonin dose in the prevention of toxicity in the presence of oxidation markers

Aim: To investigate the efficacy of Tenasin-C marker in the early diagnosis of cardiac toxicity after thoracic radiotherapy (RT) in rats and to provide new data on the dose of melatonin, an antioxidant/radioprotective agent. Material and Method: A total of 45 adult male Sprague-Dawley rats (200-300 g) were used in the experiment and divided equally into five groups. The first group (control group) received 1 ml saline solution intraperitoneally. The second group underwent simulation CT scan under anesthesia. Heart volume was contoured and 3D conformal radiotherapy planning was performed. Thirty minutes after intraperitoneal administration of 1 ml saline, 12 Gy radiotherapy was administered in 1 fraction using a bolus. While the 3rd-4th and 5th groups were irradiated in the same way, melatonin was given at a dose of 100 mg/kg in the 3rd group, 50 mg/kg in the 4th group and 5 mg/kg in the 5th group 30 minutes before radiotherapy instead of saline. Eight weeks later, Tenasin C levels were analyzed between groups to detect early myocardial damage. Protein oxidation, lipid peroxidation, lipid peroxidation, glycooxidation, non-enzymatic redox homeostasis biomarkers and histologic damage in the heart were analyzed to determine the effective melatonin dose. Results: Tenasin C, which was tested as a marker of early cardiac damage, was found to be higher in the group that received RT only to the heart (Group 2) at the end of the 8-week follow-up. 5 mg/kg melatonin administration was effective in preventing protein oxidation and lipid peroxidation. The levels of advanced glycation end products were significantly lower in the low dose and medium dose melatonin groups compared to the RT group, while no difference was found in the high dose group. When antioxidant markers such as Cu, Zn superoxide dismutase activity, iron ion reducing antioxidant power and total thiol groups were evaluated, it was observed that low dose melatonin caused a significant increase in these parameters, whereas moderate melatonin and high dose melatonin administration caused an increase in superoxide dismutase activity. Semi-quantitative evaluation of hematoxylin and eosin stained heart tissues showed that the heart damage was reversed in all groups treated with melatonin. Conclusion: Tenasin C is effective in detecting cardiac damage at an early stage and it is possible to prevent or reduce cardiac damage by administering 5mg/kg melatonin to rats undergoing thoracic RT before RT.