Calycosin ameliorates spinal cord injury by targeting Hsp90 to inhibit oxidative stress and apoptosis of nerve cells

Zhenbao pill is effective in protecting against spinal cord injury (SCI). We attempt to explore the characteristics of calycosin (a main monomer of Zhenbao pill) in SCI and its relative mechanism. The target of calycosin was screened using pharmacological network analysis. The SCI cell model was constructed using hydrogen peroxide (H2O2), and the animal model was developed by compressing spinal cord with a vascular clamp. Flow cytometry was conducted to test reactive oxygen species (ROS) levels and cell apoptosis. Detection of malondialdehyde (MDA) activity and Superoxide dismutase (SOD) activity were performed using relative kits. Heat shock protein 90 (HSP90) was examined using western blot and quantitative real-time PCR. Motor function tests were carried out. The hematoxylin-eosin and Nissl staining were conducted. In SCI models, ROS, MDA, and cell apoptosis were elevated, SOD and HSP90 levels were restrained, while calycosin addition reversed the above results. Besides, calycosin application or HSP90 overexpression enhanced phosphorylation of protein kinase B (Akt) but weakened that of apoptosis signal-regulating kinase 1 (ASK1) and p38, while HSP90 inhibitor 17-AAG treatment restrained the above results. Meanwhile, the injection of calycosin improved the motor function in SCI model rats. Furthermore, the pathologic results also clarified the positive effect of calycosin on SCI. HSP90 was lowly expressed in SCI models. Calycosin alleviated SCI by promoting HSP90 up-regulation and inhibiting oxidative stress and apoptosis of nerve cells. •The monomer Calycosin in the Zhenbao pill could relieve SCI.•The HSP90-Akt pathway was inhibited in SCI models.•The HSP90-ASK1-p38 pathway was promoted in SCI models.