[Effect of Xingnao Kaiqiao acupuncture technique on m6A methylation modification in cortical area of rats with cerebral ischemia-reperfusion injury].

OBJECTIVE

To observe the effects of Xingnao Kaiqiao acupuncture technique (for regaining consciousness and opening orifice) on methylation of N6-methyladenosine (m6A), and key methyltransferases and demethylases, so as to clarify the mechanism of acupuncture on cerebral ischemia-reperfusion injury (CIRI).

METHODS

Of 68 male Sprague-Dawley rats of SPF grade, 15 rats were randomly selected as a sham-operation group, and the remaining rats were subjected to the model of middle cerebral artery occlusion using the suture ligation. CIRI was induced by ischemia for 2 h followed by reperfusion. Rats that failed to modeling or died were excluded. The rest 45 rats were randomly divided into three groups, i.e. model group, acupuncture group, and non-point acupuncture group, with 15 rats in each group. The rats in the acupuncture group were treated with acupuncture at bilateral "Neiguan" (PC6) and "Shuigou" (GV26). In the non-point acupuncture group, acupuncture was delivered at three non-points, located 3 mm below the bilateral midaxillary line and 3 mm lateral to the tip of the coccyx. One intervention was operated in these two acupuncture groups and the needles were retained for 30 min. Before modeling start and 2 h after ischemia, a laser speckle flowmeter was used to monitor the cerebral blood perfusion. In 2 h of ischemia and 24 h of reperfusion, the neurological behavioral score was evaluated. The volume of rat cerebral infarction was determined by triphenyltetrazolium chloride (TTC) staining, and the level of m6A methylation in ischemic cortical area was detected by Dot blot, and the protein and mRNA expression of the demethylase i.e. fat mass and obesity-associated protein (FTO), AlkB homolog 5 (ALKBH5) and key methyltransferases, i.e. methyltransferase-like 3 (METTL3), methyltransferase-like 14 (METTL14), and Wilms' tumor 1-associated protein (WTAP) in ischemic cortical area were detected by Western blot and real-time PCR.

RESULTS

Cerebral blood perfusion decreased by>70% after 2 h ischemia. Compared with the sham-operation group, the neurobehavioral score and the percentage of cerebral infarction volume increased in the model group (P<0.01); the level of m6A methylation in the ischemic cortical area increased (P<0.01), the protein and mRNA expression of FTO decreased (P<0.01), and that of ALKBH5, METTL3, and METTL14 increased (P<0.01, P<0.05) in the model group. When compared with the model group and the non-point acupuncture group, the acupuncture group showed a decrease in the neurobehavioral score and the percentage of cerebral infarction volume (P<0.01), the level of m6A methylation in the ischemic cortical area was reduced (P<0.01, P<0.05), and the protein and mRNA expression of FTO was elevated (P<0.01).

CONCLUSION

Xingnao Kaiqiao acupuncture technique presents its protective effect on the brain in the rats with CIRI, which is related to up-regulating the expression of FTO and modulating m6A methylation.