Unveiling the reproductive risks of PFOS: testicular proteome disruption and hormonal imbalance in male rats†.

Male infertility has been linked with exposure to endocrine-disrupting chemicals, including perfluoroalkyl and polyfluoroalkyl substances (PFASs). However, the underlying mechanisms remain largely unknown. This study investigated the effects of perfluorooctane sulfonate (PFOS), a prevalent PFAS, on the testicular proteome, serum testosterone levels, and testicular histology in pre-pubertal male Sprague-Dawley rats. Rats were exposed to PFOS via drinking water at concentrations of 0 μg/mL (control), 10 μg/mL (P10), and 50 μg/mL (P50) for 21 days. Serum and testicular tissue were then collected. Serum testosterone levels were measured by enzyme-linked immunosorbent assay (ELISA), and testicular proteomic composition was assessed using tandem mass tag labeling and nanoLC-MS/MS. While there were no detectable changes in testicular histology, serum testosterone levels were significantly reduced in the P50 group compared to the control (P < 0.05). Testicular proteomic analysis identified 4619 proteins, with 4559 common to all groups. Among these, 35 were upregulated and 64 downregulated in the P10 group, while 130 were upregulated and 36 were downregulated in the P50 group (P < 0.05). Functional enrichment analysis of differentially expressed proteins (DEPs) revealed significant alterations in biological processes crucial for male reproductive function, including nucleosome assembly, translation, chromatin organization, and spermatogenesis. Notably, PFOS exposure impacted the expression of proteins involved in spermatogenesis, chromatin condensation, and sperm fertility. These findings were further supported by Western blot validation of four key DEPs. This study provides evidence that PFOS exposure alters the testicular proteome and disrupts key proteins essential for male reproductive function, offering insights into the molecular mechanisms underlying PFAS-induced male infertility.