Quantification of mRNA levels of genes associated with testosterone metabolism in Leydig cells. The cDNA samples used in Fig. 5 were adopted. The mRNA levels of genes encoding steroidogenic acute regulatory protein (Star), peripheral-type benzodiazepine receptor (Acbd3), cytochrome P450 (CYP) 11A1 (Cyp11a1), hydroxy-delta-5-steroid dehydrogenase, 3 beta- and steroid delta-isomerase 1 (Hsd3b1), CYP17A1 (Cyp17a1), and hydroxysteroid (17-beta) dehydrogenase 3 (Hsd17b3) were measured, normalized to glyceraldehyde-3-phosphate dehydrogenase (Gapdh) mRNA, and expressed as mean ± SEM (n = 3). Statistical analysis was performed using ANOVA test with Bonferroni’s correction. *P < 0.05; NS not significant between the 2,4-D-treated and vehicle (Veh)-treated mice in the same genotype. WT wild-type mice, KO Ppara-null mice