Unraveling the reproductive toxicity mechanisms of emerging environmental contaminants 6:2 and 8:2 diPAPs in male mice: an integrated transcriptome-metabolome investigation.

Epidemiological studies have shown that polyfluoroalkyl phosphate diester (diPAP) may disrupt reproductive endocrine functions, yet the underlying mechanisms have not been elucidated. Herein, adult male mice were exposed to 6:2 diPAP and 8:2 diPAP (0, 0.5, 5,50 mg/kg/day), respectively, via oral gavage for 28 days. Biochemical detection was conducted to assess the serum testosterone (T) and estradiol (E2) levels. Testicular histopathology was assessed using H&E staining, and sperm quality was evaluated via computer-assisted sperm analysis (CASA). Transcriptome sequencing and non-targeted metabolomic assays were performed on testis tissues to reveal the reproductive toxicity mechanisms. Exposure to 6:2 diPAP or 8:2 diPAP induced reproductive toxicity in adult male mice, characterized by reduced serum T levels and spermatogenic cells in the testis in the 50 mg/kg/day groups. Transcriptomic analyses revealed distinct pathway enrichments between exposure groups: 50 mg/kg/day 6:2 diPAP exhibited significant enrichment in immune system regulation, whereas 50 mg/kg/day 8:2 diPAP primarily affected pathways related to chemokine signaling and cytokine-cytokine receptor interaction signaling. Pathway analysis of metabolites showed that both compounds shared enrichment in ABC transporters, mTOR signaling, and purine metabolism. Additionally, the 8:2-diPAP uniquely altered glutathione metabolism and cysteine/methionine metabolism in male mice. Integrated analysis demonstrated significant correlations between these altered metabolites, DEGs enriched in inflammatory response pathways, and impaired seminal indices specifically within the diPAP-treated groups. In summary, our findings provide a compelling mechanistic explanation for the testicular toxicity induced by 6:2- and 8:2-diPAP exposure and contribute to developing proactive public health strategies targeting these emerging environmental contaminants.