Abstract:

Objective To discuss the protective effect of TUG-891 on ischemic stoke（IS） induced by ischemia-hypoxia， and to clarify its potential mechanism. Methods A total of 60 healthy male C57BL/6 mice were randomly divided into sham operation group（ n=20）， model group ［distal middle cerebral artery occlusion（dMCAO） group， n=20］， and model+TUG-891 group （dMCAO+TUG-891 group， n=20）. After modeling， the mice were intraperitoneally injected with TUG-891 solution （35 mg·kg?1·d?1） for 3 consecutive days. Modified neurological severity score （mNSS） and rotarod test were used to evaluate the neurological function of the mice in various groups； 2，3，5-triphenyltetrazolium chloride （TTC） staining was used to observe the cerebral infarction volumes of the mice in various groups； biochemical method was used to detect the malondialdehyde （MDA） level and superoxide dismutase （SOD） activity in the supernatant of brain tissue of the mice in various groups； Hematoxylin-Eosin （HE） and NISSL staining were used to observe the pathomerphology of brain tissue of the mice in various groups； terminal deoxynucleotidyl transferase dUTP nick-end labeling （TUNEL） staining was used to detect the apoptotic indexes of neuronal cells in brain tissue of the mice in various groups； Western blotting method was used to detect the expression levels of glucose-regulated protein 78 （GRP78）， protein kinase R-like endoplasmic reticulum kinase （PERK）， phosphorylated PERK （p-PERK）， and C/EBP homologous protein （CHOP） proteins in brain tissue of the mice in various groups. Results The mNSS and rotarod test results shoued that compared with sham operation group， the mNSS of the mice in dMCAO group was significantly increased （P<0.01）， and the time on the rod was significantly decreased （P<0.01）； compared with dMCAO group， the mNSS of the mice in dMCAO+TUG-891 group was decreased （P<0.05）， and the time on the rod was increased （P<0.05）. The TTC staining results shoued that compared with sham operation group， the volume of white infarct foci in the cerebral cortex of the mice in dMCAO group was increased （P<0.01）； compared with dMCAO group， the cerebral infarction volume of the mice in dMCAO+TUG-891 group was significantly decreased （P<0.01）. The HE staining results showed that compared with sham operation group， the cortex of the mice in dMCAO group was severely damaged， manifested by disordered arrangement of neuronal cells and obvious nuclear pyknosis in the infarct area， and the morphology of cortical infarct area of the mice in dMCAO+TUG-891 group was improved； the NISSL staining results showed that the Nissl bodies in the cortical infarct area of the mice in dMCAO group became thinner， elongated， and lost more. The pathological damage of brain tissue of the mice in dMCAO+TUG-891 group was significantly improved. Compared with sham operation group， the MDA level in brain tissue of the mice in model group was significantly increased （P<0.01）， and the SOD activity was decreased （P<0.01）； compared with model group， the MDA level in brain tissue of the mice in TUG-891 group was significantly decreased （P<0.01）， and the SOD activity was significantly increased （P<0.01）. The TUNEL staining results showed that compared with sham operation group， the apoptotic index of neuronal cells in brain tissue of the mice in dMCAO group was increased （P<0.01）； compared with dMCAO group， the apoptotic index of neuronal cells in brain tissue of the mice in dMCAO+TUG-891 group was decreased （P<0.01）. Compared with sham operation group， the expression levels of GRP78， p-PERK， and CHOP proteins in brain tissue of the mice in dMCAO group were increased （P<0.05）； compared with dMCAO group， the expression levels of GRP78， p-PERK， and CHOP proteins in brain tissue of the mice in dMCAO+TUG-891 group were decreased （P<0.05）. Conclusion TUG-891 can alleviate neurological injury caused by ischemic stroke， and its mechanism may be related to the inhibition of endoplasmic reticulum stress and apoptosis.

Key words: Ischemic stroke, G protein-coupled receptor 78, TUG-891, Endoplasmic reticulum stress, Apoptosis