Relationship between PERK pathway-mediated endoplasmic reticulum stress and reduction of cerebral ischemia-reperfusion injury by dexmedetomidine in mice / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the relationship between protein kinase RNA-like endoplasmic reticulum kinase (PERK) pathway-mediated endoplasmic reticulum stress and the reduction of cerebral ischemia-reperfusion (I/R) injury by dexmedetomidine in mice by the in vivo experiment and the cell experiment. Methods:In the in vivo experiment, 20 healthy clean-grade male mice, aged 6-8 weeks, weighing 20-30 g, were divided into 4 groups ( n=5 each) using a random number table method: sham operation group (group S), sham operation+ dexmedetomidine group (group SD), cerebral I/R group (group IR) and cerebral I/R+ dexmedetomidine group (group IRD). Cerebral I/R was established by two-vessel occlusion plus hypotension.Dexmedetomidine 25 μg/kg was intraperitoneally injected at 10 min of ischemia in group IRD and at the corresponding time point in group SD.Neurological function was assessed using modified neurological severity score at 1 h of reperfusion.The animals were then sacrificed and brain tissues were taken for determination of the expression of endoplasmic reticulum stress-related proteins such as immunoglobulin heavy chain-binding protein (BIP), eukaryotic translation initiation factor 2α (EIF-2α), phosphorylated EIF-2α (p-EIF-2α), PERK and phosphorylated PERK (p-PERK) (by Wester blot). In the cell experiment, a mouse hippocampal neuronal cell line was selected and divided into 4 groups ( n=12 each) using a random number table method: control group (group C), oxygen-glucose deprivation/restoration (OGD/R) group (group OGD/R), OGD/R+ dexmedetomidine group (group OGD/R+ D) and OGD/R+ ISRIB (PERK pathway inhibitor) group (group OGD/R+ ISRIB). Cells were exposed to 94%N 2-5%CO 2-1%O 2 and incubated in a low-glucose DMEM medium for 6 h followed by restoration to establish OGD/R model.At 30 min before OGD, dexmedetomidine (final concentration 5 mmol/L) was added in group OGD/R+ D, and ISRIB (final concentration 10 mmol/L) was added in group OGD/R+ ISRIB.After 12-h restoration was completed, the cell survival rate was detected by CCK-8 assay.At 24 of restoration, the expression of endoplasmic reticulum stress-related proteins was determined by Wester blot. Results:In the in vivo experiment, compared with group S, neurobehavioral score was significantly increased and the expression of BIP, p-EIF-2α and p-PERK in brain tissues was up-regulated in group IR ( P<0.05). Compared with group IR, neurobehavioral score was significantly decreased and the expression of BIP, p-EIF-2α and p-PERK in brain tissues was down-regulated in group IRD ( P<0.05). In the cell experiment, compared with group C, the expression of BIP, p-EIF-2α, PERK and p-PERK was significantly up-regulated, and the cell survival rate was decreased in group OGD/R ( P<0.05). Compared with group OGD/R, the expression of BIP, p-EIF-2α, PERK and p-PERK was significantly down-regulated, and the cell survival rate was increased in OGD/R+ D, OGD/R+ ISRIB groups ( P<0.05). Compared with group OGD/R+ ISRIB, the expression of PERK was significantly down-regulated ( P<0.05) and no significant change was found in the other parameters in group OGD/R+ D ( P>0.05). Conclusion:The mechanism by which dexmedetomidine reduces cerebral I/R injury may be related to inhibiting PERK pathway-mediated endoplasmic reticulum stress in mice.