SuanZaoRen decoction alleviates neuronal loss, synaptic damage and ferroptosis of AD via activating DJ-1/Nrf2 signaling pathway

Abstract

Ethnopharmacological relevance: SuanZaoRen Decoction (SZRD), a famous herbal prescription, and has been widely proven to have positive therapeutic effects on insomnia, depression and Alzheimer's disease (AD). However, the anti-AD molecular mechanism of SZRD remains to be further investigated.

Aim of the study: To elucidate the molecular mechanism of SZRD's improvement in AD's neuronal loss, synaptic damage and ferroptosis by regulating DJ-1/Nrf2 signaling pathway.

Materials and methods: LC-MS/MS was used to detect the active ingredients from SZRD. APP/PS1 mice was treated with SZRD and a ferroptosis inhibitor (Liproxstatin-1), respectively. Upon the completion of behavioral tests, Nissl staining, FJB staining, Golgi staining, immunofluorescence, immunohistochemistry, and transmission electron microscopy were preformed to evaluate the effects of SZRD on neuronal loss, synaptic damage, Aβ deposition. Iron staining, transmission electron microscopy, and iron assay kit was performed to estimate the effects of SZRD on ferroptosis. SOD kit, MDA kit, GSH kit, and GSH/GSSG kit were utilized to measure the oxidative stress levels in the hippocampus. The protein expression of TfR1, FTH1, FTL, FPN1, DJ-1, Nrf2, GPX4, SLC7A11, and ACSL4 were detected by Western blot.

Results: A total of 16 active ingredients were identified from SZRD extract. SZRD SZRD significantly alleviated learning and memory impairment in APP/PS1 mice. SZRD improved the hippocampal neuronal loss and degenerated neurons in APP/PS1 mice via inhibiting the Aβ deposit. SZRD mitigated the hippocampal synaptic damage in APP/PS1 mice. SZRD inhibited iron accumulation, and alleviated the oxidative stress level in the hippocampus of APP/PS1 mice. Meanwhile, SZRD could up-regulate the protein expression level of FPN1, DJ-1, Nrf2, GPX4 and SLC7A11 in the hippocampus, and inhibit TfR1, FTH1, FTL, and ACSL4 protein expression.

Conclusion: SZRD alleviated neuronal loss, synaptic damage and ferroptosis in AD via activating DJ-1/Nrf2 signaling pathway.

Keywords: Alzheimer's disease; DJ-1/Nrf2 signaling pathway; Ferroptosis; Neuronal loss; SuanZaoRen decoction; Synaptic damage.