Melatonin attenuates lipid peroxidation and enhances circulatory antioxidants during mammary carcinogenesis in rats

The possible protective effect of Melatonin was investigated for itsantioxidant and lipid peroxidation activity against 7,12-dimethylbenz(a)anthracene (DMBA) induced mammarycarcinogenesis in female albino Wistar rats. Mammary tumor wasdeveloped to the animals by administering 5mg/kg body weight ofDMBA orally at weekly intervals for one month. Intraperitonealadministration of melatonin 5mg/ml per animals for 15 days prior tothe first oral administration of DMBA was continued for a month.After the experimental period, oxidative stress parameters wereassessed in plasma of both control and experimental groups. Asignificant increase in lipid peroxidation levels were observed incancer induced rats while the activities of enzymic and non-enzymicantioxidants were decreased in cancer-bearing animals whencompared to control animals. Administration of melatoninremarkably reduced the lipid peroxidation activity and increased theantioxidants level in drug treated animals. This result suggests thatmelatonin shows antioxidant activity and play a protective roleagainst 7, 12-dimethylbenz(a)anthracene induced breast cancer. Theinhibitory effect of melatonin on tumor cells and its lack of side–effects, indicate that melatonin should be considered as an adjuvantdrug in the treatment of neoplastic diseases.