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.