Research on mechanism of sevoflurane in alleviating cerebral ischemia-reperfusion injury in rats through JNK signaling pathway

Objective: To explore the specific mechanism of sevoflurane in alleviating cerebral ischemia-reperfusion injury (CIRI) in rats through the c-Jun N-terminal kinase (JNK) signaling pathway.

Materials and methods: A total of 60 male specific pathogen-free Sprague-Dawley rats were randomly divided into sham group (n=20), model group (n=20), and sevoflurane group (n=20). In the sevoflurane group, sevoflurane (2.5%) was inhaled for 60 min at 24 h before the blockage of cerebral blood supply. The CIRI model was established using the suture method in the model group and sevoflurane group, while the right common carotid artery and external carotid artery were separated and ligated only, without suture placement, in the sham group. At 24 h after reperfusion, the neurological deficit score in each group was calculated, the water content in brain tissues in each group was detected based on dry-wet weight ratio, the infarction volume of brain tissues in each group was detected via 2,3,5-triphenyltetrazolium chloride (TTC) staining, and the Apoptosis rate of brain cells in each group was detected using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Moreover, the protein levels of JNK, p-JNK, B-cell lymphoma-2 (Bcl-2), and the Bcl-2 associated X protein (Bax) in brain tissues were determined using Western blotting, and the gene expressions of Bax and Bcl-2 in brain tissues were determined through fluorescence quantitative Polymerase Chain Reaction (qPCR).

Results: It was found that the water content in brain tissues and the cerebral infarction volume were significantly increased in the model group compared with those in the sham group (p<0.01, p<0.01), while they were notably decreased in the sevoflurane group compared with those in the model group (p<0.05, p<0.01). The neurological deficit score was significantly higher in the model group than that in the sham group (p<0.01), while it was remarkably lower in the sevoflurane group than that in the model group (p<0.01). According to the results of the TUNEL assay, the model group had an evidently higher Apoptosis rate of brain cells than the sham group (p<0.01), while the sevoflurane group had a lower Apoptosis rate of brain cells than the model group (p<0.05). Besides, the results of Western blotting revealed that the model group exhibited remarkably increased protein levels of JNK, p-JNK, and Bax (p<0.05, p<0.01, p<0.01) and a remarkably decreased protein level of Bcl-2 (p<0.01) compared with the sham group. Sevoflurane group had decreased protein levels of JNK, p-JNK, and Bax (p<0.05, p<0.01, p<0.01) and an increased protein level of Bcl-2 (p<0.05) in comparison with the model group. In addition, the gene expression of Bcl-2 significantly declined (p<0.01), and that of Bax remarkably rose (p<0.01) in the model group compared with those in the sham group, while the contrary is the case in the sevoflurane group compared with those in the model group (p<0.05, p<0.01).

Conclusions: Sevoflurane can regulate the protein and gene expressions of Bax and Bcl-2 and reduce Apoptosis in CIRI by regulating the JNK signaling pathway, thereby exerting a protective effect on brain tissues and improving the symptoms of neurological deficit.