Comparative effects of dimethylbenz(a)anthacene and a 15% olive-oil diet on cellular components and expression of apoptosis-related proteins in the spleen and mammary gland tumors of rats

We compared effects of a high fat diet and a carcinogen on cellular element s of the spleen and mammary gland tumors in rats. Animals were fed a 15% ol ive-oil diet and a group of them were exposed to a carcinogen, dimethylbenz (a)antracne (DMBA), in two doses of 10 mg/rat. Results of the experiments w ere evaluated after 4 months. We studied changes in the areas of different zones of the spleen related to production of B and T lymphocytes and also t he number of cells in the spleen and tumors with positive reaction to recep tors related to manifestation of apoptosis (FasL and p53) and receptors rel ated to inhibition of apoptosis (bcl-2), In the spleen, dietary fats as wel l as DMBA alone decreased the zones related to production of B lymphocytes and increased the number of T lymphocytes. The combined effect of a carcino gen and a high fat diet manifested in an increase in the number of lymphoid cells and macrophages. In tumors from rats fed a low-fat diet, an extremel y high number of lymphoid cells was seen in the border of tumors with T cel l killers as a main component of these infiltrates. In tumors from rats fed a 15% olive-oil diet, the main component of the infiltrates were macrophag es. High levels of p53(+) and bcl-2(+) cells were found in the spleen of ra ts exposed to a carcinogen. The combined effect of a carcinogen and the 15% olive-oil diet inhibited production of FasL and p53 receptors and stimulat ed synthesis of bcl-2 protein. In tumors, a carcinogen alone stimulated the high expression of FasL and p53 proteins, but in combination with the 15% olive-oil diet synthesis of these receptors decreased while production of b cl-2 protein increased sharply. This observation may serve as an additional proof of tumor-promoter effects of a high fat diet.