Role of autophagy in morphine preconditioning-induced reduction of OGD/R injury in primary cortical neurons of mice and the relationship with JNK / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of autophagy in morphine preconditioning-induced reduction of oxygen-glucose deprivation and restoration (OGD/R) injury in primary cortical neurons of mice and the relationship with c-Jun N-terminal kinase (JNK).Methods:Primary cortical neurons extracted from C57BL/6 neonatal mice within 24 h after birth were divided into 9 groups ( n=24 each) using a random number table method: control group (C group), OGD/R group, morphine preconditioning group (M group), autophagy inhibitor 3-methyladenine (3-MA) group (3-MA group), 3-MA+ morphine preconditioning group (3-MA+ M group), autophagy inhibitor chloroquine group (Ch group), chloroquine + morphine preconditioning group (Ch+ M group), JNK inhibitor SP600125 group (SP group) and SP600125 + morphine preconditioning group (SP+ M group). Morphine preconditioning: morphine was added at a final concentration of 3 μmol/L before OGD/R, and the cells were incubated for 2 h in OGD/R group. In 3-MA, Ch and SP groups, 3-MA 5 mmol/L, chloroquine 50 μmol/L and SP600125 25 μmol/L were added, respectively, and the cells were incubated for 150 min. In 3-MA+ M, Ch+ M and SP+ M groups, 3-MA 5 mmol/L, chloroquine 50 μmol/L and SP600125 25 μmol/L were added, respectively, at 30 min before morphine preconditioning. Then the cells were subjected to oxygen-glucose deprivation for 1 h followed by restoration of oxygen-glucose supply for 24 h. CCK-8 assay was used to detect the neuronal viability. The expression of JNK, phosphorylated JNK (p-JNK), microtubule-associated protein 1 light chain 3 (LC3), p62, Beclin1, caspase-3, and cleaved-caspase-3 was determined by Western blot. The autophagosomes and autolysosomes were counted using LC3-double fluorescent adenovirus transfection, and the neuronal apoptosis rate was determined by TUNEL staining. Results:Compared with C group, the neuronal viability was significantly decreased, the expression of Beclin1 was up-regulated, the expression of p62 was down-regulated, and the LC3Ⅱ/LC3Ⅰ ratio, p-JNK/JNK ratio, the number of autophagosomes and autolysosomes, cleaved-caspase-3/caspase-3 ratio and neuronal apoptosis rate were increased in OGD/R group ( P<0.001). Compared with OGD/R group, the neuronal viability, p-JNK/JNK ratio, LC3Ⅱ/LC3Ⅰ ratio and the number of autophagosomes and autolysosomes were significantly increased, the expression of Beclin1 was up-regulated, and the expression of p62 was down-regulated in M group, the LC3Ⅱ/LC3Ⅰ ratio was significantly decreased, and the expression of p62 was down-regulated in 3-MA group, the LC3Ⅱ/LC3Ⅰ ratio was significantly increased, and the expression of p62 was up-regulated in Ch group ( P<0.001), and no significant change was found in the parameters mentioned above in SP600125 group ( P>0.05). Compared with M group, the neuronal viability was significantly decreased, the LC3Ⅱ/LC3Ⅰ ratio was decreased, and the expression of p62 was up-regulated in M+ 3-MA group, the neuronal viability was significantly decreased, the LC3Ⅱ/LC3Ⅰ ratio was increased, and the expression of p62 was up-regulated in M+ Ch group, and the neuronal viability, LC3Ⅱ/LC3Ⅰ ratio and p-JNK/JNK ratio were significantly decreased, the expression of p62 was up-regulated, the number of autophagosomes and autolysosomes was decreased, the expression of Beclin1 was down-regulated, and the cleaved-caspase-3/caspase-3 ratio and neuronal apoptosis rate were increased in M+ SP group ( P<0.001). Conclusions:Morphine preconditioning can attenuate OGD/R injury by activating JNK, enhancing autophagy and inhibiting apoptosis in primary cortical neurons of mice.