Cold-inducible RNA binding protein ameliorates oxygen-glucose deprivation-induced hippocampal neuron injury through anti-apoptotic and anti-oxidative pathways

Background Therapeutic hypothermia (TH) is an important treatment after cardiac arrest to mitigate cerebral ischemia-reperfusion (I/R) injury, but its underlying mechanism remains unclear. Studies have shown that cold-inducible RNA binding protein (CIRP), as a stress-response protein, plays a key role in improving neurological outcomes following TH treatment in cases of global ischemia. Objective This in vitro study aimed to investigate the role of CIRP in primary hippocampal neuronal injury induced by oxygen-glucose deprivation/reoxygenation (OGD/R) and to explore the underlying mechanisms. Materials and Methods Primary hippocampal neurons were cultured and an OGD/R model was established. After OGD/R injury, neurons were resuscitated in normal or hypothemia (32 °C) condition for 6 h. Adenovirus transfection were used to regulate the expression of CIRP. The ultrastructure of neurons was visualized by transmission electron microscope (TEM). Flow cytometry were use to detect OGD-induced neuronal apoptosis. Reverse transcription polymerase chain reaction (RT-PCR) and western blot were used to detect the expression of CIRP mRNA and protein levels. Meanwhile, the enzyme-linked immunosorbent assay (ELISA) was used to evaluate the levels of malondialdehyde (MDA), superoxide dismutase (SOD) and gutathione (GSH). Results Hypothermia treatment could induce CIRP over-expression in neurons and reverse the down-regulation of CIRP induced by OGD/R. In addition, over-expression of CIRP could reduce the release of reactive oxygen species (ROS) induced by OGD/R through reducing MDA levels and increasing the level of SOD and GSH, and alleviated OGD/R-induced neuronal apoptosis by down regulating Caspase-3 and cleaved Caspase-3 expression and up regulating Bcl-2 expression. Furthermore, CIRP silencing enhanced neuronal OGD/R-induced apoptosis and oxidative stress. Meanwhile, as expected, neurons were seriously damaged and mitochondrial membrane ruptured after OGD/R injury, which were attenuated by CIRP over-expression or TH. Conclusions Our results showed that CIRP at least partially resisted OGD/R-induced neuronal injury by exhibiting anti-apoptotic and anti-oxidative properties. To sum up, targeting CIRP may represent potential therapeutic implications in the treatment of brain I/R injury.