Melatonin: is it an effective antioxidant for pulmonary contusion?

The goal of the present study was to evaluate the antioxidant effects of melatonin on pulmonary contusion (PC) caused by isolated blunt thoracic trauma (BTT) in an experimental rat model.

A total of 49 rats were divided into three groups: control group (CG), trauma group (TG), and melatonin group (MG). PC was induced by isolated BTT for all the groups except the control group. Intraperitoneal melatonin was administered to the MG after trauma. Blood and tissue samples were collected from the groups. Malondialdehyde (MDA), total oxidant capacity and total antioxidant capacity (TAOC), arterial blood gas, and other biochemical parameters such as urea, creatinine, alanine aminotransferase (ALT), and aspartate aminotransferase were measured. Lung tissue samples were collected for histopathology.

On day 2, blood MDA and total oxidant capacity levels were lower, and TAOC levels were higher in the MG compared with the TG (P < 0.001). Blood pH, PO2, and PCO2 of the MG significantly improved on day 2 compared with the TG (P ≤ 0.001). Compared with the TG, histologic damage scores of the MG decreased on day 2 (P = 0.013). Urea, creatinine, ALT, and aspartate aminotransferase levels of the MG on day 2 were lower than TG parameters (P = 0.01, P = 0.02, P = 0.05, and P < 0.001, respectively).

Our findings demonstrate that melatonin can improve the histopathology of PC and distant organs such as liver and kidney by diminishing oxidative stress. All these findings suggest that melatonin may be an effective new therapeutic agent for PC caused by BTT.