Abstract:

Objective To investigate the role of m6A methyltransferase 3（METTL3）/AMP⁃activated pro⁃ tein kinase（AMPK）pathway in sevoflurane（SEV）⁃induced cognitive impairment in mice. Methods The 6⁃day⁃ old mice were randomly divided into 4 groups（8 in each group）：Ctrl plus sh⁃NC group，SEV plus sh⁃NC group， Ctrl plus sh ⁃METTL3 group and SEV plus sh ⁃METTL3 group. Spatial memory was assessed by the Morris water maze test at postnatal days 60 to 65. The mice were then sacrificed to collect hippocampal tissues for analyzing mRNA m6A methylation by Dot blot. The dendrites in the DG subregion of hippocampus were observed by Golgi staining，and protein expressions of METTL3 and AMPK were detected by immunoblot analysis. In vitro assay was conducted to investigate the effect of up⁃regulation of METTL3 on mA level and AMPK mRNA stability in mouse hippocampal neuron cell line（HT⁃22）. Results Levels of m6A and methyltransferase METTL3 were significantly increased in the hippocampus of mice exposed to SEV（P < 0.05）. As compared with the sh⁃NC plus SEV group， the escape latency in the sh⁃METTL3 plus SEV group was significantly shortened（P < 0.05），the platform crossing time and quadrant time were significantly increased（P < 0.05），as well as the number of dendritic spines and expressions of BDNF and p⁃AMPK were significantly increased（P < 0.05）. METTL3⁃overexpressed plasmid signifi⁃ cantly increased m6A levels in HT⁃22 cells（P < 0.01），while significantly decreasedexpressions of BDNF and p⁃AMPK（P < 0.05）. METTL3 upregulation significantly reduced AMPK mRNA stability（P < 0.05）. Conclusions METTL3 knock⁃down can alleviate the cognitive impairment induced by SEV in young mice through a decrease in AMPK mRNA stability mediated by m6A.

Key words:

m6A methyltransferase 3, AMP?activated protein kinase, mouse, sevoflurane, cogni? tive function