Melatonin decreases oxidative stress in Drosophila melanogaster exposed to manganese

In a previous study we found that manganese induces a pro-oxidant effect on Drosophila melanogaster. In the present study the effect of melatonin (MEL; 0.43 mM) in oxidative stress markers of D. melanogaster after manganese (Mn; 30 mM) intoxication was determined after 6 days of treatment. Three groups were used: 1. Mn (exposed to Mn); 2. Control (maintained in standard medium); 3. MEL 6 d (treated with MEL). In four additional groups, the effect of MEL treatment for 40 days after the intoxication was determined: a. Mn-Control (exposed to Mn and no additional treatment for 40 days); b. Mn-MEL (exposed to Mn and treated with MEL for 40 days); c. Control 40 d (maintained in standard medium for 40 days); d. MEL 40 d (treated with MEL for 40 days). After 6 days, an increase in the concentrations of H2O2, NO center dot, MDA, protein carbonyl and 8-OHdG, and the activities of SOD, CAT, NOS and GSH-Px was observed in Mn intoxicated flies. A decrease of GSH was also detected. At 40 days, in the Mn-Control group, the increase in the concentrations of H2O2, protein carbonyl and 8-OHdG and in the activities of GSH-Px, CAT and SOD was maintained. In contrast, the concentration of GSH and MDA was decreased. Similarly the concentrations of H2O2, NO center dot, GSH and the activities of SOD, CAT, GSH-Px and NOS were decreased in the Mn-MEL group compared to the MnControl. In conclusion, the prolonged treatment with MEL mitigated the oxidative stress in D. melanogaster after exposure to Mn.