Synaptic rescue in an Alzheimer’s mouse model: low-temperature steam-derived black ginseng oligosaccharides remodel protein S-nitrosylation-NADPH oxidase axis

Synaptic loss and aberrant protein S-nitrosylation (SNO) are strongly linked to cognitive decline in both patients and animal models of Alzheimer's disease (AD). Our recent work in an AD mouse model has shed light on the role of oligosaccharides extracted from black ginseng (OSBG) in ameliorating cognitive impairment. However, the precise molecular mechanisms responsible for therapeutic efficacy of OSBG in AD are not well understood. In the present study, we employed an innovative SNOTRAP-based proteomic approach to quantify SNO proteins in the brain of APP/PS1 mice following OSBG intervention. The results revealed that differentially expressed SNO proteins, such as SNO-NOX1 and SNO- NOX5, confirmed by Western blot (WB), are significantly enriched in pathways related to oxidative stress, such as "Oxidative_stress activation of NADPH oxidase" and "Synaptic target recognition". OSBG treatment significantly alleviated oxidative stress via inhibition of NADPH oxidase activity in APP/PS1 mouse and PC12 cells by WB immunofluorescence (IF) assays. More importantly, upregulation of PSD-95 and SYN1 was detected in the hippocampal tissue of APP/PS1 mice after OSBG intervention, which was further validated by the corresponding mRNA expression levels. Consistently, histopathological analysis revealed the restoration of hippocampal cellular structure. Overall, our findings highlight the synapse-protective effect of OSBG in an AD model through regulating protein SNO levels and inhibiting NADPH oxidase activity, revealing a novel mechanism by which OSBG alleviated oxidative stress injury.