Do mineral and corn oil serve as potential endocrine disruptors in the gerbil prostate?

Vegetable oils are frequently used as a vehicle in the administration of lipophilic drugs in animal tests. However, the composition of these oils may interfere with the results. One alternative to reduce this potential bias is the use of mineral oil, which is not supposed to interfere in the physiology of experimental models, since this oil is considered to be innocous. The present study shows for the first time the effects of the oral administration of corn and mineral on the prostate, demonstrating their interference in homeostasis and revealing their potential to act as endocrine disruptors. Mineral oil treatment increased the expression of AR and ERα and serum estradiol concentrations, while corn oil increased the expression of positive cells for both types of estrogen receptors. The variation in the expression of these hormone receptors resulted in morphological changes in the prostate.

Pathological lesions and global DNA methylation in rat prostate under streptozotocin-induced diabetes and melatonin supplementation.

Chronic hyperglycemia increases production of reactive oxygen species, which favors carcinogenesis. The association between diabetes and prostate cancer is controversial. Melatonin has antioxidant, anti-inflammatory, and antiproliferative properties. We investigated whether low doses of melatonin prevent the tissue alterations caused by diabetes and alter prostate histology of healthy rats. We also investigated whether experimental diabetes promoted the development of pathological lesions in the ventral prostate of rats. Melatonin was provided in drinking water (10 µg/kg/day) from age 5 weeks until the end of experiment. Diabetes was induced at 13 weeks by administration of streptozotocin (40 mg/kg, ip). Rats were euthanized at 14 or 21 weeks. Histological and stereological analyses were carried out and the incidence and density of malignant and pre-malignant lesions were assessed. Immunohistochemical assays of α-actin, cell proliferation (PCNA), Bcl-2, glutathione S-transferase (GSTPI), and DNA methylation (5-methylcytidine) were performed. Melatonin did not elicit conspicuous changes in the prostate of healthy animals; in diabetic animals there was a higher incidence of atrophy (93%), microinvasive carcinoma (10%), proliferative inflammatory atrophy, PIA (13%), prostatitis (26%), and prostate intraepithelial neoplasia, PIN (20%) associated with an increase of 40% in global DNA methylation. Melatonin attenuated epithelial and smooth muscle cell (smc) atrophy, especially at short-term diabetes-and normalized incidence of PIN (11%), inflammatory cells infiltrates, prostatitis (0%) and PIA (0%) at long-term diabetes. MLT was effective in preventing inflammatory disorders and PIN under diabetic condition. Although MLT has antioxidant action, it did not influence DNA methylation and not avoid carcinogenesis at low doses.