The anti-Alzheimer's disease effects of ganoderic acid A by inhibiting ferroptosis-lipid peroxidation via activation of the NRF2/SLC7A11/GPX4 signaling pathway

Alzheimer's disease (AD) is a degenerative disease of the central nervous system, characterized by a gradual decline in cognitive and memory abilities, social disorders, and behavioral abnormalities. Ferroptosis, an iron-dependent type of programmed cell death, is closely associated with the pathogenesis of AD. Ferroptosis is characterized by the accumulation of iron within cells, leading to increased oxidative stress, and ultimately lipid peroxidation and cell death. Ganoderic acid A (GAA), one of the major pharmacologically active components in Ganoderma lucidum, exhibits an excellent neuroprotective effect against AD. However, it is unclear whether GAA improves the symptoms of AD by inhibiting ferroptosis. This study investigated the anti-AD effects of GAA through both in vivo and in vitro experiments, and determined its molecular mechanism from the perspective of ferroptosis modulation. The results showed that GAA administration attenuated hippocampal neuronal loss, improved mitochondrial ultrastructure, and enhanced the memory and learning ability of the AD mice. In vitro assays suggested that GAA effectively protected HT22 AD cells against ferroptosis-related morphological damage, enhanced their antioxidant capacity, maintained their iron metabolism, and reduced mitochondrial dysfunction. Moreover, the immunofluorescence and western blotting results showed that the levels of NFE2 like bZIP transcription factor 2 (NRF2), glutathione peroxidase 4 (GPX4), and solute carrier family 7 member 11 (SLC7A11) both in the hippocampus of APP/PS1 mice and amyloid beta (Aβ)_25-35-induced HT22 AD cells were markedly enhanced after GAA administration. In summary, these results revealed that GAA improves AD by activating on the NRF2/SLC7A11/GPX4 axis to inhibit ferroptosis-lipid peroxidation.