Timing of Antioxidant Pretreatment With Melatonin, Vitamin C, and Vitamin E in Ischemia-Reperfusion Injury: A Rat Inferior Epigastric Island Flap Model.

Abstract

Free flap surgeries represent significant advancements in reconstructive surgery. Despite surgical progress, ischemia-reperfusion injury (IRI) due to vascular complications remains a challenge, potentially leading to flap loss. Various strategies, including surgical methods and pharmacological treatments, have been explored to mitigate IRI. Among these, antioxidant treatments have garnered interest, but research on the optimal timing of antioxidant administration is lacking. This study addresses this gap by investigating the timing of antioxidant pretreatment. In this experimental study, a 6 × 3 cm² inferior epigastric island flap was elevated in 40 male Wistar Albino rats and subjected to 8 h of ischemia followed by reperfusion. The animals were divided into five groups: a control group without ischemia-reperfusion (IR), an IR group receiving saline, and three treatment groups pretreated with melatonin (10 mg/kg), vitamin C (200 mg/kg), and vitamin E (40 mg/kg), administered 7 days preoperatively, 30 min before ischemia, or 30 min before reperfusion. Blood samples were obtained on postoperative days 1 and 7 to assess total antioxidant capacity. Flap photographs were taken and tissue biopsies were collected on postoperative day 7 for histopathological, immunohistochemical, and biochemical analyses. The mean necrosis rate was 33.5% in the IR group compared to 6.3% in the 7-day pretreatment group (I7) (p < 0.001). Histopathological evaluation showed significant improvement in inflammatory and vascular parameters in antioxidant-treated groups compared to IR (p < 0.05), while collagen organization was significantly better only in the I7 group (p = 0.0014). Immunohistochemical analysis revealed reduced eNOS, caspase-3, and IL-1β expression in antioxidant-treated groups and higher VEGF expression in the I7 group (p < 0.05). No significant differences were observed between groups in biochemical parameters. Initiating antioxidant pretreatment 7 days prior to surgery significantly enhances flap viability, highlighting the importance of timing for optimal outcomes in elective free flap procedures.