Chlorogenic Acid Mitigates Ferroptosis by Activating the Nrf2/GPX4 Pathway through Keap1 Blockade in Vascular Dementia Rats

Chlorogenic acid (CGA) is a dietary phenolic acid widely distributed in daily food and plants, but its role in vascular dementia (VaD) is still unclear. Hence, this study aimed to investigate whether CGA could rescue cognitive impairment in VaD, providing a new option for drug discovery. Novel object recognition and Morris water maze experiments revealed that CGA enhanced the learning and memory abilities in VaD rats. Nissl staining, Western blot, and transmission electron microscopy results demonstrated that CGA inhibited neuronal loss in the hippocampal CA1 region of VaD rats, increased the expression of synaptic-related markers SYP and PSD95, thickened the postsynaptic density, and suppressed mitochondrial ridge rupture in neurons. GSH detection, MDA detection, and Western blot experiments indicated that CGA alleviated hippocampal GSH reduction and MDA elevation and increased the protein levels of GPX4 and SLC7A11. Cell activity, ROS detection, lipid peroxidation detection, intracellular Fe2+ level detection, GSH detection, and Western blot revealed that CGA inhibited the increase of intracellular Fe2+, ROS, and lipid peroxidation induced by OGD in PC12 cells, mitigated GSH reduction, and increased the protein levels of GPX4, SLC7A11, SYP, and PSD95. Western blot and immunofluorescence staining showed that CGA increased the expression of pSer40-Nrf2 in the hippocampal tissue of VaD rats and PC12 cells, promoting Nrf2 nuclear translocation. Knockdown of Nrf2 prevented CGA from rescuing ferroptosis and synaptic damage induced by OGD in PC12 cells, as well as Nrf2 pathway activation. Molecular docking analysis suggested that CGA competitively bound to the Kelch domain of Keap1 with Nrf2 and then promoted Nrf2 release and activated downstream signaling pathways. In conclusion, our study suggests that CGA may activate the Nrf2 signaling pathway by disrupting the interaction between Nrf2 and Keap1 proteins, thereby inhibiting hippocampal neuronal ferroptosis and synaptic damage and ameliorating cognitive impairment in VaD. Practical Applications. Vascular dementia (VaD) stands as the second most prevalent type of dementia following Alzheimer's disease. However, there is no effective clinical treatment drug available, and its pathogenic mechanisms remain elusive. This study proposed that CGA might activate the Nrf2-GPX4 signaling pathway by competitively binding to Keap1, thereby attenuating hippocampal neuronal ferroptosis and synaptic damage and consequently ameliorating cognitive impairment in VaD. Our study may provide a novel option for drug research and development for VaD.