Abstract: BACKGROUND: It was found that moxibustion can inhibit the inflammatory factors in the serum of rats with cerebral ischemia/reperfusion injury, resist oxidative stress, inhibit cell apoptosis, and effectively reduce cerebral ischemia/reperfusion injury.
OBJECTIVE: To observe the effects of different moxibustion intervention time on the expression levels of nucleotide binding oligomerization domain-like protein 3 inflammasome (NLRP3), cysteine aspartase (caspase-1), apoptosis-related speck-like protein, exfoliatin-D protein, interleukin-1β and interleukin-18 in rats with cerebral ischemia/reperfusion injury, and to explore its action mechanism.
METHODS: SD rats were randomly divided into sham operation group (n=9) and operation group (n=36). The model of focal cerebral ischemia/reperfusion injury was established by middle cerebral artery occlusion in the operation group. After successful modeling, the rats in the operation group were further divided into model group, moxibustion 10-minute group, moxibustion 15-minute group and moxibustion 30-minute group, with 9 rats in each group. Rats in the moxibustion 10-minute, 15-minute and 30-minute groups were given moxibustion at “Baihui, Dazhui and Zusanli”, respectively, once a day for a total of 7 days. The neurological deficits of rats were evaluated by LONGA method. The cerebral infarction was observed by 2,3,5-triphenyltetrazolium chloride staining. The pathological changes of brain tissue were observed by hematoxylin-eosin staining. The contents of interleukin-1β and interleukin-18 in serum of rats in each group were detected by ELISA. Immunohistochemistry and western blot assay were used to detect the expression levels of NLRP3, caspase-1, apoptosis-related spot-like protein and gasdermin D in the ischemic cortex of rats in each group.
RESULTS AND CONCLUSION: Compared with the sham operation group, the neurological deficit score of the model group was significantly increased (P < 0.01). Compared with the model group, the neurological deficit score of the moxibustion groups was significantly reduced (P < 0.01). Compared with the sham operation group, the infarct volume of the model group was significantly increased (P < 0.01). Compared with the model group, the infarct volume of the moxibustion groups was significantly reduced (P < 0.01); the infarct volume of the rats was smallest in the moxibustion 30-minute group (P < 0.05). Compared with the model group, the contents of inflammatory factors interleukin-1β and interleukin-18 in the serum of rats in the moxibustion groups were decreased (P < 0.01). Compared with the moxibustion 10-minute group, the contents of inflammatory factors in the serum of rats in the moxibustion 30-minute group were significantly decreased (P < 0.05). Compared with the model group, the expression of NLRP3, apoptosis-related spot-like protein, Caspase-1 and gasdermin D protein in the ischemic cortex of the moxibustion groups was significantly decreased (P < 0.01). Compared with the moxibustion 10-minute and 15-minute groups, the expression of protein in the moxibustion 30-minute group was significantly decreased (P < 0.05). It is concluded that moxibustion at Baihui, Dazhui and Zusanli can reduce cerebral ischemia/reperfusion injury, among which moxibustion for 30 minutes has the best effect, and its mechanism may be related to the inhibition of pyroptosis mediated by NLRP3/Caspase-1 pathway. 

Key words: moxibustion, pyroptosis, cerebral ischemia/reperfusion injury, NLRP3, inflammasome, Caspase-1