Aim: 

We previously demonstrated that high fat diets exert a modulatory effect on the experimental mammary carcinogenesis, stimulating in the case of a high corn oil diet (HCO) and inhibitory in that of a high virgin olive oil diet (HVOO). It has been suggested that high fat diets may modify sexual maturation and, therefore, mammary gland differentiation, a putative key factor on its susceptibility to transformation. We studied the effects of HVOO and HCO diets on the growth and puberty of female Sprague-Dawley rats.

Methods: 

Animals were distributed into 3 groups: the control low fat diet group; the HCO group, fed postweaning the HCO diet, and the HVOO group, fed postweaning the HVOO diet. Rats were euthanized at 24, 36, 51 and 100 days of age. We evaluated several parameters of growth and sexual maturation.

Results: 

The HCO diet increased the body weight at the end of the assay and significantly advanced the day of vaginal opening (VO) followed by HVOO and control groups. There weren't changes in the body weight at VO day. This was accompanied by modifications in mammary gland differentiation. The kisspeptin hypothalamic expression increased in HCO group by 36 days of age, in accordance with the advanced day of VO.

Conclusion: 

High fat diets, specially the HCO diet, advance initiation of puberty and induce changes in the morphology of the mammary gland. Thus, the advance in maturation can be one of the mechanisms of the modulatory effects of high fat diets on breast cancer.

This study was supported in part by grants from "Plan Nacional de I+D+I 2004-2007" (AGL2006-07691/ALI) and from "Fundación Patrimonio Comunal Olivarero 2008-2012" (FPCO2008-165396). "Agencia para el Aceite de Oliva del Ministerio de Medio Ambiente y de Medio Rural y Marino" (AAO2008-165.000).