Calcium dysregulation contributes to mitochondrial dysfunction and hippocampal necroptosis in TDCPP-induced cognitive impairment

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP), a widely used organophosphorus flame retardant, has been increasingly associated with adverse neurological effects; however, the mechanisms linking TDCPP exposure to hippocampal injury and cognitive impairment remain incompletely understood. In this study, we investigated whether calcium dysregulation and mitochondrial dysfunction contribute to TDCPP-induced neuronal injury. Subchronic TDCPP exposure in mice caused significant cognitive deficits and hippocampal neuronal loss, accompanied by activation of RIPK1/RIPK3/MLKL-related necroptotic signaling. In SH-SY5Y cells, TDCPP induced marked mitochondrial dysfunction, as evidenced by decreased mitochondrial membrane potential, enhanced mitochondrial permeability transition pore opening, and excessive mitochondrial fragmentation. Mechanistically, TDCPP induced intracellular Ca²⁺ overload and increased the calpain/CDK5 pathway, resulting in enhanced Drp1 phosphorylation and mitochondrial fission. Pharmacological inhibition of TRPA1 with HC-030031 markedly attenuated TDCPP-induced Ca²⁺ overload, calpain/CDK5-Drp1 pathway activation, mitochondrial dysfunction, and necroptosis-related neuronal injury. Consistently, genetic knockdown of TRPA1 produced similar protective effects against TDCPP-induced Ca²⁺ dysregulation, mitochondrial dysfunction, and necroptosis-related signaling. In contrast, Mdivi-1 treatment reduced mitochondrial fragmentation and necroptotic injury but did not substantially affect upstream Ca²⁺ dysregulation. Additionally, TDCPP exposure was accompanied by cytosolic mtDNA accumulation and increased expression of cGAS-STING pathway components and ZBP1 in the hippocampus, suggesting the involvement of mitochondrial damage-associated innate immune responses. Collectively, these findings suggest that Ca²⁺ dysregulation contributes to Drp1-associated mitochondrial dysfunction and hippocampal necroptotic injury during TDCPP-induced cognitive impairment, providing new mechanistic insight into the molecular basis of hippocampal neuronal vulnerability.