17α-Hydroxyprogesterone Mediates Mo-Induced Sperm-Mediated Transgenerational Inheritance of Impaired Spermatogenesis

Growing evidence suggests that exposure to metals, such as molybdenum, contributes to significant health risks. However, very little is known about its potential male reproductive toxicity due to paternal exposure across generations. The aim of the present study was to investigate the male reproductive toxicity of paternal exposure to sodium molybdate (Na₂MoO₄) across generations and reveal the underlying mechanism. Adult F0 male C57 mice were administered sodium molybdate at doses of 0.01 and 0.1 mg/kg/day. The assessment included testicular toxicity evaluation and metabolomic profiling, followed by mechanistic studies in vivo and in vitro from F0 to F2. A large sample of case-control study including 958 subjects verified the findings. Reduced sperm counts and damages to seminiferous tubules across generations were observed in Mo-treated groups. Metabolomics analysis revealed a transgenerational elevation of 17α-hydroxyprogesterone (17α-OHP) in the testes of Mo-treated groups. Apoptosis and ferroptosis were enhanced in GC-2 cells in vitro after 17α-OHP treatment and were validated in vivo. Molecular competition experiments revealed that 17α-OHP competes for the NADPH binding site in FSP1, hindering FSP1's catalytic function, as supported by metabolomics analysis. Enzyme activity analysis found a reduction in FSP1 activity after 17α-OHP treatment, promoting ferroptosis and apoptosis in GC-2 cells in vitro. AHCY was identified as a potential target and was reduced after Mo exposure both in vivo and in vitro, accompanied by testicular DNA hypomethylation and elevated expression of key enzymes for 17α-OHP synthesis across generations, including Hsd3b and Cyp17a1. Human studies revealed that Mo exposure was associated with an increased risk of male infertility via 17α-OHP. This study innovatively elucidated the mechanisms by which paternal Mo exposure induced transgenerational male reproductive toxicity through metabolic and epigenetic alterations using human, mouse, and in vitro models.