Gut microbiome contributes to 6PPD-quinone induced cognitive impairment through PI3K/Akt signaling

Studies show that N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone (6PPD-Q) accumulates in the central nervous system, but its role in cognitive impairment and underlying mechanisms remain unclear. Morris water maze assay revealed that 6-PPDQ significantly impairs cognitive function, particularly learning and memory. HE staining revealed alterations in the hippocampal DG and CA3 regions of exposed mice, including sparse cell arrangement, blurred boundaries, nuclear condensation, and a reduction in Nissl bodies. Fecal microbiota transplantation from 6-PPDQ-exposed mice to normal mice induced cognitive deficits and hippocampal pathological damage. Western Blot assay showed that 6-PPDQ exposure resulted in inhibition of PI3K/AKT signaling. Moreover, blunted PI3K/AKT signaling was observed in mice transplanted with 6-PPDQ-associated mice fecal microbiota. Further analysis of 16S rDNA assay identified a total of 30 differential bacteria at the genus level, including 8 upregulated bacteria such as g_Helicobacter and 22 downregulated bacteria such as g_Prevotellaceae_NK3B31_group. In conclusion, this study uncovers gut microbiome mediates 6PPD-Q-induced cognitive impairment through inhibiting of PI3K/Akt signaling, and provides a basis for further investigation into gut microbiome's protective effects on 6-PPDQ-induced nervous system injury.