[Astragaloside Ⅳ alleviates cerebral ischemia-reperfusion injury in rats by activating JAK2/STAT3 pathway]

Based on the Janus kinase 2(JAK2)/signal transducer and activator of transcription 3(STAT3) pathway, the inhibitory effect and relevant mechanism of astragaloside-Ⅳ(AS-Ⅳ) on cerebral ischemia-reperfusion injury(CIRI) in rats were explored. Sixty rats were randomly divided into six groups: sham operation group, model group, low-dose AS-Ⅳ group(10 mg·kg~(-1)), medium-dose AS-Ⅳ group(20 mg·kg~(-1)), high-dose AS-Ⅳ group(30 mg·kg~(-1)), and edaravone group(3 mg·kg~(-1)), with 10 rats per group. Except for the sham operation group, the middle cerebral artery occlusion/reperfusion(MCAO/R) model was established in all other groups. Rats in the drug-administered groups were intraperitoneally injected with the corresponding drugs from 7 d before surgery to 3 d after reperfusion, while the rats in the sham operation groups were given an equal volume of normal saline. Neurological behavior scores of rats were recorded; cerebral infarct volume was measured by 2,3,5-triphenyltetrazolium chloride(TTC) staining; enzyme-linked immunosorbent assay(ELISA) was used to detect the contents of interleukin-1β(IL-1β), interleukin-6(IL-6), tumor necrosis factor-α(TNF-α), superoxide dismutase(SOD), and malondialdehyde(MDA) in serum; hematoxylin-eosin(HE) staining and Nissl staining were performed to observe the pathological changes of cerebral tissue; the ultrastructure of cells was observed by transmission electron microscope; terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling(TUNEL) was used to detect neuronal apoptosis; immunohistochemical staining was applied to determine the protein expressions of apoptotic proteins B-cell lymphoma/leukemia-2(Bcl-2), and Bcl-2 associated X(Bax); immunofluorescence staining was used to detect the protein expressions of phosphorylated(p)-JAK2 and p-STAT3; western blot was employed to detect the protein expressions of cleaved cysteine aspartate specific protease-3(cleaved caspase-3), Bax, Bcl-2, p-JAK2, JAK2, p-STAT3, and STAT3 proteins. Compared with the sham operation group, the model group showed significant increases in neurological behavior scores, cerebral infarct volume, inflammatory factors(IL-1β, IL-6, and TNF-α), and MDA, a decrease in SOD, upregulated expressions of Bax, cleaved caspase-3, p-JAK2, and p-STAT3, as well as a downregulated expression of Bcl-2. Compared with the model group, groups with each AS-Ⅳ dose can reverse the above indicator changes and promote the nuclear translocation of p-STAT3. In conclusion, AS-Ⅳ can activate the JAK2/STAT3 pathway and inhibit neuronal apoptosis, thereby improving CIRI in rats.