Effects of HFPO-DA (GenX) exposure on placental glycolysis and metabolic microenvironment in pregnant rats

Hexafluoropropylene oxide dimer acid (HFPO-DA; GenX) is an environmentally persistent per- and polyfluoroalkyl substance (PFAS) alternative whose placental toxicity remains poorly understood. Pregnant Sprague-Dawley rats (n = 20, 5 dams/group) received oral HFPO-DA at 0, 1, 10, or 100 mg/kg·day from gestational day (GD) 0–19. Placental tissues collected on GD20 were analysed by targeted metabolomics, lipidomics, histopathology, immunohistochemistry (IHC), and immunofluorescence (IF). After false discovery rate (FDR) correction, three energy metabolites were significantly altered ( q  < 0.05): oxaloacetate and glutamate were downregulated, while pyruvate was dose-dependently upregulated, consistent with restricted TCA cycle entry. Lipidomics identified 148 nominally significant lipid species, with elevated ceramides and long-chain fatty acids alongside reduced triglycerides, a pattern suggestive of impaired mitochondrial β-oxidation capacity. Histopathology revealed dose-dependent villous hyperplasia, trophoblast disorganization, and vascular lesions at the high dose. Protein analysis showed decreased SDHB, increased HIF-1α and PDK1, and a non-significant rise in PDHA1, collectively consistent with a shift toward Warburg-like metabolic reprogramming. These findings suggest that gestational HFPO-DA exposure may disrupt placental energy and lipid homeostasis at supra-environmental doses, identifying placental metabolism as a potentially sensitive target of next-generation PFAS.