New Approach Methodologies (NAMs) reveal triphenyl phosphate (TPP) disrupts lipid metabolism in estuarine fish via PPARγ activation: A concentration-dependent transcriptomic and molecular docking study

There is an urgent need for a more efficient and ethical approach to chemical toxicity assessment. The emergence of New Approach Methodologies (NAMs) based on fish embryos transcriptomics provides a promising alternative. Triphenyl phosphate (TPP) — a pervasive contaminant in estuaries — disrupts lipid homeostasis in mammals via PPARγ activation, yet its ecotoxicological impacts on estuarine fish remain unknown. Leveraging NAMs, this study integrates concentration-dependent transcriptomics (CDT), molecular docking, and phenotypic toxicity assays to unravel effects of TPP on embryonic development and lipid metabolism in the benthic fish Mugilogobius chulae . We found that TPP induced significant lethality (LC₅₀ = 1.86 × 10 6  ng/L) and teratogenicity (EC₅₀ = 5.27 × 10 5  ng/L), suppressing spontaneous movement, heart rate, and hatching. At concentrations of 5270 ng/L and 52,700 ng/L, TPP elevated triglycerides, total cholesterol, and hepatotoxicity markers (alanine aminotransferase / aspartate aminotransferase). CDT analysis identified fatty acid metabolism pathways as the most sensitive targets, with TPP upregulating PPARγ while downregulating CD36 and ACSL5 — indicating blocked fatty acid oxidation and explaining lipid accumulation. Crucially, co-exposure with PPARγ antagonist GW9662 reversed metabolic disorders, validating the mechanistic role of PPARγ. Furthermore, molecular docking confirmed that TPP binds PPARγ with agonist-like affinity. This work establishes a NAM-based framework for deciphering the toxicity of contaminants of emerging concern in estuarine ecosystems, offering novel tools for ecological risk assessment.