Moxibustion preconditioning reduces inflammatory response in rats with cerebral ischemia-reperfusion injury by regulating PI3K / AKT / mTOR signaling pathway.

OBJECTIVES: To observe the effect of moxibustion preconditioning on inflammatory response in rats with cerebral ischemia reperfusion injury (CIRI), so as to explore its mechanisms underlying improving CIRI.

METHODS: Seventy-five male SD rats were randomly divided into sham operation, model, moxibustion preconditioning 3 days (Moxi 1), moxibustion preconditioning 5 days (Moxi 2) and moxibustion preconditioning 7 days (Moxi 3) groups, with 15 rats in each group. Moxibustion was applied at "Baihui"(GV20), "Dazhui"(GV14) and "Zusanli"(ST36) for 20 min once a day, totally for 3, 5 or 7 days. Thirty minutes after the last moxibustion treatment, the CIRI model was established by occlusion of the middle cerebral artery. The neurological deficit score was assessed by using Longa's method. The infarct size of the brain assessed after staining with 2% triphenyltetrazolium chloride (TTC). The morphological changes of cortical neurons were observed by HE staining. The contents of inflammatory factors interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), S-100β protein (S-100β) and neuron-specific enolase (NSE) were detected by ELISA. The expression of phosphatidylinositol-3-kinase (PI3K), p-PI3K, protein kinase B (AKT) and mammalian target of rapamycin (mTOR) proteins in the ischemic cortex tissues were detected by immunohistochemistry and Western blot.

RESULTS: Compared with the sham operation group, the neurological function score and the percentage of cerebral ischemic volume were increased ( P <0.01). The contents of serum IL-1β, TNF-α, S-100β and NSE were significantly increased ( P <0.01), while the protein expressions of PI3K, p-PI3K, AKT and mTOR in the cerebral cortex were significantly decreased ( P <0.01) in the model group. Compared with the model group, the neurological function score and the percentage of cerebral ischemic volume were significantly decreased ( P <0.01). The contents of serum IL-1β, TNF-α, S-100β and NSE were significantly decreased ( P <0.01), and the expressions of PI3K, p-PI3K, AKT and mTOR proteins in the cerebral cortex were significantly increased ( P <0.01) in three moxibustion groups. Compared with the Moxi 1 and Moxi 2 groups, the above indicators were significantly improved in rats of the Moxi 3 group ( P <0.01, P <0.05).

CONCLUSIONS: Moxibustion preconditioning can significantly improve the neurological function of rats after ischemia-reperfusion, inhibit serum inflammatory factors IL-1 β and TNF-α, inhibit brain tissue injury markers S-100β and NSE, which may be related to the activation of PI3K/AKT/mTOR signaling pathway. The protective effect of moxibustion preconditioning for 7 days on CIRI was better than that of 5 days and 3 days.