Melatonin is effective in attenuating cisplatin-induced neurotoxicity

Cisplatin (Cis) is a chemotherapeutic agent that has many side effects. Neurotoxicity is one of the most important of these side effects. Oxidative stress and neuroinflammation are the best-known mechanisms in the pathogenesis of neurotoxicity development. In this study, we aimed to determine whether melatonin (Mel), with antioxidant and anti-inflammatory effects, is effective in preventing Cis-induced neurotoxicity. Forty-eight male Sprague-Dawley rats were divided into six groups (n = 8) as follows: control (0.9% NaCl), vehicle (5% ethanol), Cis (6 mg/kg), Cis (6 mg/kg) + vehicle (5% ethanol), Mel (20 mg/kg), and Cis (6 mg/kg) + Mel (20 mg/kg) groups. Cis was administered as a single dose on the 3rd day of the experiment while Mel was given for 5 days. All administrations were performed via intraperitoneal injection. After injections, T-maze, rotarod, and hot plate tests were performed to evaluate cognitive, motor, and sensory functions, respectively. Following sacrification oxidative stress markers, cholinergic function, and proinflammatory cytokines were studied from brain homogenates. Cis impaired cognitive function and motor performance in the Cis and Cis+Vehicle groups. The drug also increased oxidative stress in the brain. Mel significantly improved brain oxidant/antioxidant status and also decreased the overproduction of proinflammatory cytokines (superoxide dismutase activities in Cis+Vehicle and Cis+Mel groups: 104.55 ± 9.50 µU/mg protein vs. 150.13 ± 4.70 µU/mg protein, respectively, p < 0.05; tumor necrosis factor-α levels in Cis and Cis+Mel groups: 40 pg/ml vs. 20 pg/ml, respectively, p < 0.05). It seems that Mel can improve Cis neurotoxicity. For a more firm conclusion, further studies using Mel at different doses with larger groups should be performed.