Effects of diet-induced hypercholesterolemia on testosterone-regulated protein expression in mice liver

We report here testosterone deficiency in diet-induced hypercholesterolemic mice. We attempted to compare the liver protein profiles between hypercholesterolemic and normal mice by using the technology of proteomics. Protein extractions from mice livers were separated by two-dimensional electrophoresis and the gels were analysed with image analysis software 2D Elite 4.0. The differentially expressed proteins were identified primarily by comparing with reference gel images in the SWISS 2DPAGE database and then confirmed by peptide mass fingerprinting. Sixteen differentially expressed protein spots (>2-fold) were detected and 8 of which were identified as major urinary proteins, carbonic anhydrase III, and glutathione S-transferase P2, which are known to be regulated by androgens. The expression of these three proteins was statistically lower in the livers of hypercholesterolemic mice. Meanwhile, the testosterone levels in serum, testis, and liver were lower in hypercholesterolemic mice than those in normal mice, when human chorionic gonadotrophin was injected intramuscularly. These results suggest a testosterone deficiency in diet-induced hypercholesterolemic mice.