Proteomic Analysis of Mouse Testis Reveals Perfluorooctanoic Acid-Induced Reproductive Dysfunction via Direct Disturbance of Testicular Steroidogenic Machinery

Perfluorooctanoic acid (PFOA) is a ubiquitous environmental pollutant suspected of being an endocrine disruptor; however, mechanisms of male reproductive disorders induced by PFOA are poorly understood. In this study, male mice were exposed to 0, 0.31, 1.25, 5, and 20 mg PFOA/kg/day by oral gavage for 28 days. PFOA significantly damaged the seminiferous tubules and reduced testosterone and progesterone levels in the testis in a dose-dependent manner. Furthermore, PFOA exposure reduced sperm quality. We identified 93 differentially expressed proteins between the control and the 5 mg/kg/d PFOA treated mice using a quantitative proteomic approach. Among them, insulin like-factor 3 (INSL3) and cytochrome P450 cholesterol side-chain cleavage enzyme (CYP11A1) as Leydig-cell-specific markers were significantly decreased. We examined in detail the expression patterns of CYP11A1 and associated genes involved in steroidogenesis in the mouse testis. PFOA inhibited the mRNA and protein levels of CYP11A1 and the mRNA levels of 17β-hydroxysteroid dehydrogenase (17β-HSD) in a dose-dependent manner. Moreover, in vitro study showed the reduction in progesterone levels was accompanied by decreased expression of CYP11A1 in cAMP-stimulated mLTC-1 cells. Our findings indicate that PFOA exposure can impair male reproductive function, possibly by disturbing testosterone levels, and CPY11A1 may be a major steroidogenic enzyme targeted by PFOA.