The neuroprotective role of Hsp70 in the enhancement of antioxidant defense in the neurons

Introduction. Proteins in the HSP70 class have been known for their neuroprotective properties for a long time. However, the mechanisms by which they exert their effects are not fully understood. Therefore, we aimed to determine how HSP70 contributes to optimal antioxidant protection of rat cortical neurons during cerebral ischemia/hypoxia.

Methods. We simulated neurodestruction in vitro by adding 80 μmol/L of 1-chloro-2,4-dinitrobenzene (CDNB) (a toxic amount) and 100 μmol/L of glutamate (modeling glutamate excitotoxicity) to neuronal suspensions. Brain thiol–disulfide system status was assessed by fluorimetry according to reduced glutathione and oxidized glutathione content. The spectrophotometric method was used to measure the levels of free SH groups and glutathione reductase, glutathione peroxidase, and glutathione transferase activities. A solid-phase ELISA method was used to determine the HSP70 levels.

Results. When CDNB was administered to the neurons in vitro, there was a decrease in cell viability, a depletion of cytosolic and mitochondrial GSH pools, a significant increase in ROS, and decreased HSP70 levels. Administration of HSP70 to the neurons preincubated with CDNB resulted in an increase in GSH levels and a decrease in ROS. HSP70 administration increased the functional activity of the glutathione system in the neurons.

Conclusion. HSP70, proteins with pronounced neuroprotective properties, mobilize antioxidant resources in the neurons under ischemic/hypoxic conditions, preventing the development of oxidative stress by increasing cytosolic and mitochondrial glutathione levels.