Modifications of Western-type diet regarding protein, fat and sucrose levels as modulators of steroid metabolism and activity in liver. Issue 165 (January 2017) - Krawczyńska, Agata
Highlights: The Western-type diet with decreased protein content impairs the liver antioxidant system. The lower protein level in high-fat diet decreased liver T conversion to E2 and E3. Liver Esr1 mRNA level was increased when low-protein, high-fat diet was consumed. The liver Srd5a1 and Ar gene expression is positively correlated with body weight. The fat reduction in Western-type diet restores plasma proportion between T and E2. Abstract: The aim of the study was to evaluate whether the modification of the Western-type diet (high-fat, high-sucrose diet rich in saturated fatty acids) considering macronutrients content would influence hepatic metabolism and activity of steroids. For 3 weeks Wistar rat were fed the Western-type diet (21% fat, 35% sucrose, 19% protein, lard) and its modifications regarding dietary protein (10 and 19%), fat (5 and 21%) and sucrose (0 and 35%) levels. The steroid 5α-reductase type 1 ( Srd5a1 ) and androgen receptor ( Ar ) gene expression as well as testosterone (T) conversion towards 5α-reduced derivatives in liver were positively correlated with body weight gain. The Western-type diets with decreased protein content regardless of the sucrose level exerted the most negative effect on the antioxidant system decreasing catalase ( Cat ), sodium dismutase ( Sod1 ) and glutathione peroxidase ( Gpx1 ) gene expression as well as Cat and Gpx activity and total antioxidant status, simultaneously intensifying lipid peroxidation. The impaired antioxidant system was accompanied by decreased level of hepatic T metabolism towards estrogens: 17β-estradiol (E2) and estriol, and increased estrogen receptor type 1 ( Esr1 ) gene expression. Liver Esr1 mRNA level was differently correlated with T (positively) and E2 (negatively) plasma levels. Whereas the fat reduction in Western-type diet restored the plasma proportion between T and E2. In conclusion it could be stated that Western-type diet modification relating to protein, sucrose and fat content can influence hepatic steroid metabolism and activity; however the estrogens and androgens metabolism in liver would be connected with impairment of liver function or catabolic activity, respectively.