Tributyl phosphate disrupts neuronal autophagy: potential involvement of TLR4 in cell and rat models

Tributyl phosphate (TBP), a widely used organophosphate ester, exhibits lipophilic characteristics that enable it to cross the blood-brain barrier. Although its neurotoxicity has been confirmed, the underlying molecular pathways remain unclear. This study examined whether TLR4-associated autophagy disruption contributes to TBP-induced neuronal damage. Autophagy was activated with rapamycin (RAPA) and TLR4 was knocked down using siRNA. TBP exposure upregulated TLR4 expression and downregulated autophagy-related markers. Autophagic flux analysis assays using bafilomycin A1 further revealed that TBP impaired autophagosome biogenesis instead of lysosomal dysfunction. Autophagy activation and TLR4 knockdown each partially attenuated TBP-induced oxidative stress, inflammation, and alterations in neuroinjury markers. Moreover, inhibiting TLR4 partially reversed the decrease in autophagy levels caused by TBP. Molecular docking predicted TBP may bind to the TLR4 extracellular domain, providing a testable framework for future validation. These findings identify TLR4-regulated autophagy suppression as a candidate mechanism for TBP neurotoxicity.