Effects of electroacupuncture on repairing neurological damage following ischemic stroke based on miR-381-mediated SDF-1/CXCR4 signaling pathway.

OBJECTIVES: To investigate the effects of electroacupuncture (EA) on the miR-381, leucine-rich repeat C4 protein (LRRC4), and downstream stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4) signaling pathway in rat model of ischemic stroke, and to explore the mechanism by which EA improves neurological damage following ischemic stroke.

METHODS: Among 50 SPF male SD rats, 10 rats were randomly selected into a sham surgery group, and the remaining rats were used to establish the middle cerebral artery occlusion (MCAO) model. The 30 successfully modeled rats were randomly divided into a model group, an EA group, and an agonist group, with 10 rats in each group. The rats in the EA group received EA at "Baihui" (GV 20) and "Dazhui" (GV 14), with disperse-dense wave, a frequency of 2 Hz/10 Hz, and a current intensity of 1 mA, 30 min per session, once daily for a total of 14 days. The rats in the agonist group received miR-381 agonist injections into the lateral ventricle, with 10 μL per injection, every 7 days for a total of 2 injections. After intervention, ZeaLonga neurobehavioral deficit score was observed in each group. HE staining was performed to observe the morphological changes in the ischemic brain tissue of rats in each group. ELISA was used to measure the levels of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and nerve growth factor (NGF) in serum. Western blot was employed to detect the protein expression of LRRC4, SDF-1, CXCR4, and extracellular regulated protein kinase 1 (ERK1) in the ischemic brain tissue. Real-time PCR was utilized to assess the expression of miR-381 and LRRC4, SDF-1, CXCR4, ERK1 mRNA in the ischemic brain tissue.

RESULTS: After intervention, the brain tissue showed disordered cell arrangement, reduced quantity, and significant interstitial edema, with numerous vacuoles in the model group. The pathological changes mentioned above were alleviated in the brain tissue of rats in the EA group and the agonist group. Compared with the sham surgery group, the rats in the model group exhibited increased ZeaLonga neurobehavioral deficit scores, elevated levels of serum TNF-α and IL-6 ( P <0.01), and decreased serum NGF level ( P <0.01)；the protein expression of SDF-1, CXCR4 and ERK1 in ischemic brain tissue was reduced ( P <0.01), while LRRC4 protein expression was increased ( P <0.01)；the expression of miR-381, as well as SDF-1, CXCR4 and ERK1 mRNA in ischemic brain tissue was decreased ( P <0.01), while LRRC4 mRNA expression was increased ( P <0.01). Compared with the model group, the rats in the EA group and the agonist group showed decreased ZeaLonga neurobehavioral deficit scores and reduced levels of serum TNF-α and IL-6 ( P <0.05, P <0.01), and increased serum NGF levels ( P <0.05, P <0.01); the protein expression of SDF-1, CXCR4 and ERK1 in ischemic brain tissue was increased ( P <0.01), while LRRC4 protein expression was decreased ( P <0.01)；the expression of miR-381, as well as SDF-1, CXCR4 and ERK1 mRNA in ischemic brain tissue was increased ( P <0.05, P <0.01), while LRRC4 mRNA expression was decreased ( P <0.01).

CONCLUSIONS: EA at "Baihui" (GV 20) and "Dazhui" (GV 14) may promote the repair of neurological damage following ischemic stroke by up-regulating miR-381 to selectively inhibit LRRC4 expression, thereby activating the SDF-1/CXCR4 signaling pathway.