Effect of electroacupuncture pretreatment on ferroptosis in neurons of rats with cerebral ischemia-reperfusion injury

Abstract

To observe the effect of electroacupuncture（EA）preconditioning on ferroptosis in rats with cerebral ischemia-reperfusion injury （CIRI）, so as to explore the neuroprotective mechanism of EA preconditioning. Male SD rats were randomly divided into sham operation, model, EA, inhibitor and inducer groups with 20 rats in each group. The CIRI model was established by modified Zea Longa occlusion of the middle cerebral artery. Before modeling, EA treatment （2 Hz/15 Hz, 1-2 mA） was applied to "Baihui"（GV20）, "Fengfu"（GV16） and "Dazhui"（GV14） for rats of the EA group, 20 min a day for 7 consecutive days. Rats of the inhibitor group were intraperitoneally injected with ferristatin-1（25 mg/kg）at a slow and uniform rate. Rats of the inducer group were intraperitoneally injected with Erastin（100 mg/kg） after 7 days of EA preconditioning, once every 2 h for a total of 4 times. The CIRI models were prepared 2 d later after the above interventions finished by thread-occlusion. The degree of neurological impairment was evaluated by modified Zea Longa score. The percentage of infarct size was calculated by TTC staining. The ultrastructure of neurons in hippocampus was observed by transmission electron microscope. The contents of ferrous ion （Fe2+）, malondialdehyde （MDA） and glutathione （GSH） in cerebral tissue and reactive oxygen species （ROS） in serum were determined by biochemical method. The changes of mitochondrial membrane potential in rats brain tissues were detected by flow cytometry. The mRNA and protein expression levels of glutathione peroxidase 4 （GPX4）, acyl-CoA synthetase long-chain family member 4 （ACSL4）, transferrin receptor （TFRC）, 15-lipoxygenase （15-LOX） and cyclooxygenase-2 （COX-2） in the ischemic hippocampal region of CIRI rats were detected by real-time quantitative PCR and Western blot, respectively. Compared with the sham operation group, the neurological impairment score, the percentage of cerebral infarction area, the contents of MDA and Fe2+ in cerebral tissue as well as ROS in serum, the protein and mRNA expression levels of ACSL4, TFRC, 15-LOX, COX-2 in hippocampal tissue were increased （P<0.01）, while the content of GSH in cerebral tissue, the protein and mRNA expression levels of GPX4 in hippocampal tissue were decreased （P<0.01）, and mitochondria in brain tissue were significantly damaged （P<0.01） in the model group. Compared with the model group, the above indexes were all reversed （P<0.05, P<0.01） in the EA group and inhibitor group. Compared with the EA group, the neurological impairment score, the percentage of cerebral infarction area, the contents of MDA and Fe2+ in cerebral tissue as well as ROS in serum, the protein and mRNA expression le-vels of ACSL4, TFRC, 15-LOX, COX-2 in hippocampal tissue were increased （P<0.05, P<0.01）, while the content of GSH in cerebral tissue, the protein and mRNA expression levels of GPX4 in hippocampal tissue were decreased （P<0.01, P<0.05）, and mitochondria in brain tissue were significantly damaged （P<0.05） in the inducer group. EA preconditioning has neuroprotective effect on CIRI rats, which may be related to inhibiting ACSL4/TFRC/15-LOX/COX-2 expression and increasing GSH/GPX4 expression.