PPARα Activation-Mediated Testosterone Reduction as the Key Adverse Outcome Pathway for Cd-Induced Male Infertility: A Novel Integrated Approach

Cadmium (Cd)-induced male infertility and its mechanisms
have been
widely studied, but systematic construction of an adverse outcome
pathway (AOP) network and identification of key AOPs remained unknown.
This study integrated network toxicology, single-cell sequencing,
NHANES research, animal experiments, and molecular modeling to construct
an AOP network and identify the key AOP for Cd-induced male infertility.
We constructed an AOP network comprising 9 AOPs and confirmed that
PPARα activation leading to testosterone reduction and subsequent
male infertility is the key AOP. Single-cell sequencing analysis showed
downregulation of testosterone synthesis genes (Cyp11a1) in Cd-exposed Leydig cells, whereas NHANES data showed a threshold
effect between blood Cd (about 1.17 μg/L) and serum testosterone,
indicating that high Cd exposure can reduce serum testosterone levels.
Subnetwork analysis prioritized PPARα activation and increased
the number of reactive oxygen species as potential critical MIEs. In vivo experiments further validated that the PPARα
inhibitor (GW6471) more effectively reversed Cd-evoked sperm count
reduction than the antioxidant N-acetylcysteine.
Taken together, these results validated PPARα activation-mediated
testosterone reduction as the key pathway for Cd-induced male infertility
and established a novel integrative paradigm for identifying key AOPs
in environmental toxicology.