Involvement of TMAO in exacerbating arsenic-induced neurotoxicity by activating the PERK/eIF2α/ATF4 pathway

Arsenic (As), a widely recognized environmental pollutant, has been implicated in the pathogenesis of various neuropsychiatric disorders, including anxiety and depression. Trimethylamine N-oxide (TMAO), a microbiota-host co-metabolite derived from dietary quaternary amines (e.g., choline), has been associated with the progression of multiple neurological disorders. This study demonstrates that the gut microbiota-derived metabolite TMAO potentiates As-induced neurotoxicity. Using network toxicology, we identified genes targeted by As and TMAO in depression, revealing significant enrichment in pathways related to apoptosis, ferroptosis, and endoplasmic reticulum (ER) stress. In C57BL/6 mice, a high-choline diet exacerbated As-induced depressive behaviors, hippocampal damage, and astrocyte depletion, which were mediated by elevated TMAO levels. High-performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) analysis confirmed that TMAO enhanced arsenic accumulation in plasma and brain tissues. In vitro experiments further demonstrated that TMAO exacerbated As-induced oxidative stress, DNA damage, mitochondrial dysfunction, apoptosis, and ferroptosis. Mechanistically, TMAO upregulated the ER stress PERK/eIF2α/ATF4 signaling pathway in response to As exposure. Knockdown of PERK attenuated As- and TMAO-mediated apoptosis and ferroptosis in cultured cells. Collectively, these findings indicate that dietary choline exacerbates arsenic-induced depressive-like phenotypes by increasing TMAO levels and activating the PERK/eIF2α/ATF4 signaling pathway.