Metabolic changes in mammary carcinogenesis induced in female rats by irradiation and DMBA administration: the effect of melatonin in chemopreventionproject

The aim of our project was to determine selected metabolic parameters in fe male Wistar:Han rats after the induction of mammary carcinogenesis by ioniz ing radiation and 7,12-dimethylbenz(a)anthracene (DMBA). The rats were irra diated continuously by 96 mGy daily doses of gamma rays for up to 15 days. After exposure DMBA was administered 3 x 10 mg/rat by gavage. During exposu re to radiation and six months after last DMBA;administration animals drank melatonin at a concentration of 100 mug/ml of tap water. Pit the end of th e trial animals were sacrificed, tumors were excised and selected parameter s of lipid and carbohydrate metabolism were determined. Melatonin did not i nfluence mammary tumor incidence, frequency and latency, but diminished tum or volume. The concentration of serum cholesterol was lower and that of tri acylglycerols was higher in tumor-bearing rats. Liver cholesterol decreased and that of phospholipids increased in tumor-bearing and non-tumor-bearing rats. The concentrations of triacylglycerols increased in the bone marrow of both groups. Administration of melatonin increased the serum glucose, ch olesterol and phospholipids levels in non-tumor-bearing rats (cholesterol) or in both tumor-bearing and non-tumor-bearing animals. Melatonin also decr eased the concentration of lipid peroxides in the bone marrow of tumor-bear ing and non-tumor-bearing rats.