The Protective Effects of Ecdysterone on Cognitive Impairment through Regulating Akt/GSK-3β/Nrf2 Signaling Pathway and Oxidative Stress in Cognitive Mice Model and Aβ-Induced Cell Neurotoxicity

Background: Severe neurological condition like Alzheimer's disease (AD) has a significantly negative impact on families and society, wherein there is no proven cure. As one of the principal active constituents of Achyranthes bidentata Blume, ecdysterone (ECR) has demonstrated antioxidant and cognitive dysfunction improvement effects. Nonetheless, the mechanism underlying the improvement of cognitive dysfunction by ECR remains unclear. This study sought to ascertain whether ECR may allebviate cognitive impairment by reducing oxidative stress via activation of the nuclear factor erythroid-2-related factor-2 (Nrf2) antioxidant system through Akt/GSK3 beta pathway. Methods: In terms of the experimental procedure, we determined the neuroprotective benefits of ECR in vivo via a cognitive impairment model of senescence-accelerated mouse prone 8 (SAMP8), we performed procedures such as behavioral testing, biochemical assaying, Nissl and TUNEL stainings, as well as flow cytometry, immunohistochemistry and western blotting. Furthermore, we investigated the underlying mechanistic action of ECR by activating PC12 cells with beta-amyloid peptide fragment 25-35 (A beta 25-35). Results: In vivo studies showed that ECR effectively improved cognitive impairment in SAMP8 via enhancement of learning and memory capabilities, but decreased oxidative stress, apoptosis and neuronal damage in the hippocampus. During the in vitro study, we observed that ECR dose-dependently reduced the oxidative stress and apoptosis that were induced in PC12 cells by A beta 25-35. Additionally, the use of Akt inhibitors further established the potential of ECR to control Nrf2 through activation of the Akt/GSK3 beta pathway and protect the PC12 cells from A beta 25-35 induced damage. Conclusions: These findings offer proof that ECR reduces cognitive impairment by triggering the Nrf2 antioxidant system via the Akt/GSK3 beta pathway and offer fresh information on ECR's potential as a promising therapeutic development candidate for AD.