Role of PERK‐mediated Pathway in the Effect of Mild Hypothermia after Cerebral Ischaemia/reperfusion

Background: Hypothermia is an effective method of reducing brain injury caused by a variety of neurological insults. It is aimed to elucidate whether a change in the expression of PERK-mediated pathway proteins is an indicator of the neuro-protective effect of mild hypothermia after cerebral ischaemia/reperfusion. Methods: One hundred and ninety-two male C57BL/6 mice were randomly divided into three groups: a sham group, a cerebral normothermic ischaemia/reperfusion (I/R) group and a cerebral hypothermic I/R group. A cerebral ischaemia model was established by ligating the bilateral common carotid artery for 15 min. Mice in the hypothermia group stayed in a cage that was set at 33 degrees C, sprayed with a spray of 70% ethanol, and blown with two high-speed fans. The state of neurons was assessed on micropreparations stained with haematoxylin-eosin and TUNEL. The expressions of GRP78, p-perk, p-eif2 alpha, ATF4 and CHOP were measured by western blot analysis 6, 12, 24 and 72 h after reperfusion. Results: The number of surviving cells was significantly higher in the hypothermia group than in the group without hypothermia (p <.05). The GRP78 expression in the hypothermia group was statistically higher (p <.05) than in the ischaemia/reperfusion group. Optical densities of p-perk, p-eif2 alpha and ATF4 in hippocampus CA1 neurons ischaemia were statistically significantly lower in the hypothermia group than in the ischaemia/reperfusion group (p <.05). The CHOP expression in the hypothermia group was statistically lower (p <.05) than in the ischaemia/reperfusion group. Conclusion: Mild hypothermia for 6 h promoted moderate neuroprotection by mediating the expression of GRP78, p-PERK, p-eIF2 alpha, ATF4 and CHOP.