Effects of the high-fat and high-cholesterol diet and metformin supplementation on testosterone biosynthesis regulators (StAR, CYP11A1, 3β-HSD, CYP17A1 and 17 β-HSD) in the male mice: (a) Protein expressions in each group were measured using western blot analysis, and β-actin was used for normalization; (b) relative density analysis of the protein bands. Data are expressed as means ± SD of duplicate experiments (n = 6–9 per group). * p < 0.05 as determined by one-way ANOVA followed by LSD post hoc test. NC, normal diet; HFC, high-fat and high-cholesterol diet; HFC + Met, HFC with metformin supplementation.