Vitaminas e Minerais

Obesity Decreases Serum Selenium Levels in a Mammary Tumor Zucker Rat Model

Abstract

Reza Hakkak

Previously, we reported that obese Zucker rats had increased susceptibility to DMBA-induced mammary tumors compared to lean Zucker rats. In that experiment, 36% of the obese ovariectomized rats developed mammary tumors while lean ovariectomized rats developed no mammary tumors. The obese sham-operated rats developed mammary tumors (59%) compared to 30% of the lean sham-operated rats. On the other hand, several lines of evidence suggest that lower serum selenium (Se) may play an important role in increasing the risk of several types of cancers (e.g., colon, breast and prostate cancers). In the present study, we used this Zucker rat model to examine the effect of obesity on Se status, and the serum Se level was determined by graphite furnace atomic absorption spectrometry. We found that the serum Se levels did not differ by ovariectomy when comparing the combined sham-operated groups with the combined ovariectomized groups; similarly, there was little difference among the four sub-groups. However, obesity decreased the serum Se levels in the combined obese groups (480 ± 10.9 ng/ml) when compared with the combined lean groups (511 ± 10.3 ng/ml) (P<0.05). In summary, our data demonstrate for the first time that obesity decreases serum Se levels in an animal model and suggest that serum Se may play an important role mammary carcinogenesis.