Butylated hydroxytoluene (BHT) induces zebrafish spinal cord defects and scoliosis by inhibiting the hedgehog pathway

Butylated hydroxytoluene (BHT) is widely employed as an antioxidant in various industries. However, concerns persist regarding its safety and environmental impact, as its toxicological mechanisms remain poorly understood. Zebrafish embryos were exposed to BHT at 3, 5, and 7 mg/L to assess developmental toxicity. BHT exposure dose-dependently induced spinal cord malformations concomitant with reduced larval motility. Mechanistically, BHT suppressed Hedgehog signaling, evidenced by dysregulation of Shha, Gli1, and Smo. Notably, pharmacological activation of the Hh pathway by SAG rescued both structural defects and gene expression anomalies, confirming Hh inhibition as the primary toxicity mechanism. These results indicate that BHT inhibits Hh signaling, disrupting floor plate function and leading to spinal curvature.