Bilobalide attenuates chronic restraint stress-induced neurotoxicity and cognitive impairment through glucocorticoid receptor-dependent BDNF/TrkB/PI3K/Akt signaling

Chronic stress is a major contributor to hippocampal neurotoxicity and cognitive dysfunction. However, mechanism-oriented interventions remain limited. Bilobalide is a chemically defined sesquiterpene lactone from Ginkgo biloba with reported neuroprotective activity. Nevertheless, its effect on chronic stress-induced cognitive injury and its relationship to glucocorticoid receptor (GR) signaling remain unclear. Here, we evaluated bilobalide in chronic restraint stress (CRS) mice and in corticosterone (CORT)-challenged HT22 hippocampal neurons. Bilobalide improved short-term recognition, long-term recognition, and spatial memory in CRS mice, and alleviated neuronal injury in the hippocampal CA1, CA3, and dentate gyrus regions. These effects were accompanied by reduced lipid peroxidation, recovery of antioxidant capacity, attenuation of systemic inflammatory cytokine release and hippocampal inflammatory gene expression, suppression of apoptosis-related signaling, and preservation of dendritic architecture, synaptic ultrastructure, and synaptic proteins. Bilobalide also restored hippocampal BDNF/TrkB/PI3K/Akt signaling. In vivo and in vitro fractionation/immunofluorescence experiments showed that bilobalide restrained stress-enhanced GR nuclear translocation, and GRE-reporter assays showed reduced GR transactivation. Molecular docking and cellular thermal shift assay supported cellular target engagement of GR by bilobalide. Importantly, GR knockdown blunted bilobalide-mediated rescue of oxidative injury and of BDNF/TrkB/PI3K/Akt-associated synaptic signaling in CORT-injured HT22 cells. These data indicate that bilobalide protects against chronic stress-induced hippocampal neurotoxicity and memory impairment, at least in part, by limiting maladaptive GR signaling and preserving neurotrophic-synaptic homeostasis. Bilobalide therefore merits further evaluation as a mechanistically defined lead compound for stress-associated cognitive dysfunction.