Piperonyl Butoxide Impairs Porcine Oocyte In Vitro Maturation by Suppressing the p38 MAPK Signaling Pathway and...

Piperonyl butoxide (PBO) is one of the most widely used insecticide synergists in agricultural and veterinary applications worldwide. There is increasing concern regarding the potential reproductive risks to livestock from its environmental persistence, while its reproductive toxicity in livestock species remains largely unknown. A porcine oocyte in vitro maturation (IVM) model was employed to explore how PBO exposure affects oocyte maturation and its underlying cellular mechanisms. SMART-seq-based single-cell transcriptomics was used to elucidate the molecular pathways involved. PBO exposure significantly inhibited cumulus expansion, reduced first polar body (PB1) extrusion, and caused meiotic arrest. It also disrupted gene expression associated with mitochondrial dynamics and oxidative stress, leading to pronounced mitochondrial dysfunction. Transcriptomic analysis showed significant enrichment of differentially expressed genes in autophagy, mitophagy, and MAPK signaling pathways. PBO exposure increased LC3-mitochondria colocalization and upregulated key mitophagy-related proteins, indicating excessive mitophagy. Activation of p38 MAPK by anisomycin partially rescued PBO-induced mitophagy abnormalities in porcine oocytes. These findings indicate that PBO impairs porcine oocyte maturation by suppressing the p38 MAPK signaling pathway, thereby triggering excessive mitophagy.