Effects of acupuncture on iron metabolism in the hippocampus of the rats with cerebral ischemia-reperfusion injury based on the imbalance of iron homeostasis

Abstract

Objective

This study aimed to observe the effects of acupuncture on iron metabolism in the hippocampus of rats with cerebral ischemia-reperfusion injury (CIRI) and to explore the mechanism of acupuncture on neural repair in CIRI rats.

Methods

After general feeding for 3 days, 16 of 48 healthy Sprague–Dawley rats were selected according to a random number table to form a sham-occlusion group, and the models were prepared in the remaining rats. After successful modeling, the rats were randomized into model and acupuncture groups, with 16 rats in each group. The CIRI models were prepared using the modified Zea Longa suture-occlusion method. In the acupuncture group, the rats were fixed and acupuncture was delivered at “Shuigou” (GV26), “Dazhui” (GV14), and “Baihui” (GV20), and the needles were manipulated once every 15 min. In the sham-occlusion and model groups, rats were fixed without acupuncture. The intervention was performed for 30 min in each group, once every 12 h, seven times. The degree of neurological impairment was assessed by using the modified Garcia score. Cerebral blood flow (CBF) was monitored using a laser speckle blood flow imaging system. The cerebral infarction area ratio was measured using triphenyltetrazolium chloride staining. Ferric ion aggregation in brain tissue was noted using Prussian blue staining. The ferric ion and glutathione (GSH) contents of the hippocampal tissue on the ischemic side were detected using ferric ion and GSH kits. The protein expression of transferrin receptor 1 (TFR1), iron regulatory protein 2 (IRP2), and ferroportin (FPN) was detected via western blotting.

Results

(1) Before intervention, compared with the sham-occlusion group, the Garcia neurological score was significantly reduced in the model and acupuncture groups (both P < 0.01). After the intervention, compared with the sham-occlusion group, the Garcia neurological score in the model group decreased significantly (P < 0.01), and the score in the acupuncture group was elevated compared with the model group (P < 0.05). Compared to before the intervention, the Garcia neurological score increased after the intervention in the acupuncture group (P < 0.05). (2) Compared with the sham-occlusion group, in the model group, CBF was reduced, the infarct area was significantly enlarged, ferric ion aggregation increased in the hippocampus, the content of ferric ion increased, and that of GSH decreased significantly (both P < 0.01), while the protein expression of TFR1 and IRP2 was upregulated and that of FPN was downregulated (both P < 0.05). When compared with the model group, in the acupuncture group, CBF was increased, the infarct area was reduced (P < 0.01), the ferric ion aggregation was reduced in the hippocampus, the content of ferric ion decreased, and that of GSH increased significantly (P < 0.05, P < 0.01); the protein expression of TFR1 and IRP2 was downregulated and that of FPN was upregulated (both P < 0.05).

Conclusion

Acupuncture can alleviate CIRI, which may be related to the regulation of iron homeostasis-associated transferrin in the hippocampus, attenuation of ferric ion aggregation in hippocampal tissue, reduction of lipid peroxidation, and inhibition of ferroptosis.