Title: (empty line)
Author: Herr Dr. Amoneit
Last saved by: Saritas, Sevim

Influence of High Fat Diets on Puberty, Sexual Maturation 
and Breast Cancer Risk.
R. Escrich^1, R. Moral^1, M. Solanas^1, E. Vela^1, M.A. Manzanares^1, M.C. Ruíz de Villa^2, I. Costa^3 and E. Escrich^1
^1Medicine School, Universitat Autònoma de Barcelona, ^2Dep. Statistics, Universitat de Barcelona, ^3Dep. Pathology, Consorci Hospitalari Parc Taulí, Spain

Several evidences have demonstrated the importance of early-life events, including nutrition, in the susceptibility to breast cancer. We investigated the effects of high fat diets on growth and maturation, mammary gland development, and its susceptibility to transformation. Female Sprague-Dawley rats were fed a low fat (LF), high corn oil from weaning (HCO) or from induction (LF-HCO), or high extra-virgin olive oil from weaning (HEVOO) or from induction (LF-HEVOO). Animals were gavaged with 7,12-dimethylbenz(a)anthracene (DMBA) at 53 days, and euthanized at 24, 36, 51, 100 and 246 days. Results showed that the administration of the HCO diet, but not the HEVOO diet, increased the body weight evolution and the mass index of the animals. Both high fat diets increased hepatic expression of lipid metabolism genes, but only the HEVOO diet increased UCP-2 expression. The day of vaginal opening was significantly advanced in the HCO group, followed by HEVOO and LF groups. Hypothalamic Kiss1 levels tended to be higher in HCO group by 36 days. We observed little changes in the mRNA expression of hormone receptors by the effect of dietary lipids, and no significant modifications in serum hormone levels. Both high fat diets increased the number of corpus luteum in the ovaries at 51 days and induced subtle changes in the morphology of the mammary gland at post-puberty. β-casein mRNA increased over the time in the mammary glands of all groups and it correlated with glandular density at the end of the study. The HCO diet has a clear stimulating effect on mammary carcinogenesis, whereas clinical parameters of the carcinogenesis of the animals fed the HEVOO diet were more similar to those of the control LF group. Our data suggest that high corn oil and high extra-virgin olive oil exert different influence on growth and sexual maturation. Such influence may be one of the mechanisms of their differential modulatory effects on mammary tumorigenesis. Moreover these results highlight the transcendence that dietetic habits from childhood may have on mammary cancer risk.