Oxidative stress is involved in the pathogenesis of Alzheimer's disease (AD), which is linked to reactive oxygen species (ROS), lipid peroxidation, and neurotoxicity. Emerging evidence suggests a role of nuclear factor (erythroid-derived 2)-like 2 (Nrf2), a major source of antioxidant response elements in AD. The molecular mechanism of oxidative stress and ferroptosis in astrocytes in AD has not yet been fully understood. Here, we aim to investigate the mechanism by which Nrf2 regulates the ferroptosis of astrocytes in AD. Postmortem frontal cortex tissues from patients with AD and nondemented controls and brain tissue from the 3xTg AD mouse model and wild-type mice (10 months old) were used. Immunofluorescence staining for Nrf2, the ROS marker NADPH oxidase 4 (NOX4), and GFAP was performed. We further induced Nrf2 deficiency in mouse astrocytes by using RNAi and assessed the changes in ROS, ferroptosis, lipid peroxidation, and mitochondrial dysfunction by using western blotting and immunofluorescence staining. We found decreased expression of Nrf2 and upregulated expression of NOX4 in the frontal cortex from patients with AD and cortex of 3xTg mice compared to control groups. We demonstrated that Nrf2 deficiency led to ferroptosis-dependent oxidative stress-induced ROS with downregulated heme oxygenase-1 and glutathione peroxidase 4 and upregulated cystine glutamate expression. Moreover, Nrf2 deficiency increased lipid peroxidation, DNA oxidation, and the mitochondrial fragmentation in mouse astrocytes. In conclusion, these results suggest that Nrf2 promotes ferroptosis of astrocytes involving oxidative stress in AD.

Alzheimer's disease (AD) is featured by abnormal &beta-amyloid (Abeta) deposition, neurofibrillary tangle formation, downstream mitochondrial dysfunction, oxidative stress, and synaptic loss. Gastrodin, a phenolic glycoside, has shown neuroprotective effect and used in the treatment of a range of brain diseases. Here we aim to assess the mechanisms and signaling pathways involved in the neuroprotective effect of gastrodin in murine neuroblastoma N2a cells expressing human Swedish mutant amyloid precursor protein (N2a/APP). The levels of pre- and postsynaptic proteins, amyloid precursor protein C-terminal fragments (APP-CTFs), levels of tau, glycogen synthase kinase-3beta (GSK-3beta), extracellular regulated kinase (ERK), and c-Jun N-terminal Kinase (JNK) were assessed by Western blotting. Flow cytometry assays for mitochondrial membrane potential (JC1) and reactive oxidative stress, as well as immunofluorescence staining for lipid peroxidation (4-hydroxynonenal) and DNA oxidation (8-hydroxy-2'-deoxyguanosine), were performed. We found that gastrodin treatment increased the levels of presynaptic SNAP25, synaptophysin, and postsynaptic PSD95, reduced phosphorylated tau protein Ser396, and APP-CTFs in N2a/APP cells. In addition, gastrodin reduced the levels of reactive oxygen species generation, lipid peroxidation, and DNA oxidation, reestablished mitochondrial membrane potential. Upregulated levels of phosphorylated-GSK-3beta, reduced levels of phosphorylated-ERK, and phosphorylated-JNK were involved the protective effect of gastrodin. In conclusion, we demonstrated a neuroprotective effect of gastrodin in N2a/APP cell line.