Relationship between METTL3-mediated m6A methylation modification and SIRT1 during sevoflurane post-conditioning-induced mitigation of cognitive impairments in a mouse model of hemorrhagic shock and resuscitation / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the relationship between methyltransferase-like 3(METTL3)-mediated RNA N6-Methyladenosine (m6A) methylation modification and silent information regulator factor 1 (SIRT1) during sevoflurane post-conditioning-induced mitigation of cognitive impairments in a mouse model of hemorrhagic shock and resuscitation(HSR).Methods:Forty clean-grade healthy male C57BL/6 mice, aged 8-10 weeks, with a body weight ranging from 22-26 g, were assigned into 5 groups ( n=8 each) using a random number table method: sham operation group, HSR group, sevoflurane post-conditioning + HSR group (SP+ HSR group), over-expression of METTL3 gene rAAV + sevoflurane post-conditioning + HSR group (METTL3+ SP+ HSR group), and over-expression of METTL3 gene rAAV negative control + sevoflurane post-conditioning + HSR group (NC+ SP+ HSR group). The HSR model was established by withdrawing 40% of the total blood volume from mice through the right carotid artery within 30 min, followed by reinfusion of the withdrawn blood over 30 min 1 h later. The SP+ HSR group underwent HSR modeling first and then inhaled sevoflurane (end-tidal concentration 2.4%) for 30 min starting from the time point immediately after blood transfusion. The Sham group and HSR group inhaled a mixture of 70% O 2 and 30% CO 2 for 30 min at the corresponding time points. In METTL3+ SP+ HSR group and NC+ SP+ HSR group, the corresponding virus 450 nl was injected into bilateral hippocampus at 4 weeks before establishing the model.Morris water maze and novel object recognition tests were conducted at 72 h after developing the model to assess the learning and memory abilities. After the end of behavioral tests, the expression of METTL3 and SIRT1 in hippocampal tissues was detected using Western blot, the expression of SIRT1 mRNA was measured using qRT-PCR, and the methylation of RNA m6A was detected using Dot blot. Results:Compared to Sham group, the escape latency was significantly prolonged at 1-6 days, the time spent in the target quadrant was shortened, the number of crossing the original platform was decreased, the novel object recognition index was decreased, the expression of METTL3 was up-regulated, the expression of SIRT1 protein and mRNA was down-regulated, and the methylation of RNA m6A was increased in HSR group( P<0.05). Compared to HSR group, the escape latency was significantly shortened at 1-6 days, the time spent in the target quadrant was prolonged, the number of crossing the original platform was increased, the novel object recognition index was increased, the expression of METTL3 was up-regulated, the expression of SIRT1 protein and mRNA was down-regulated, and the methylation of RNA m6A was increased, the novel object recognition index was increased, the expression of METTL3 was down-regulated, the expression of SIRT1 protein and mRNA was up-regulated, and the methylation of RNA m6A was decreased in SP+ HSR group( P<0.05). Compared to SP+ HSR group, the escape latency was significantly prolonged at 2-6 days, the time spent in the target quadrant was shortened, the number of crossing the original platform was decreased, the novel object recognition index was decreased, the expression of METTL3 was up-regulated, the expression of SIRT1 protein and mRNA was down-regulated, and the methylation of RNA m6A was increased in METTL3+ SP+ HSR group( P<0.05), and no significant change was found in the aforementioned indicators in NC+ SP+ HSR group ( P>0.05). Conclusions:The mechanism by which sevoflurane post-conditioning alleviates cognitive dysfunction is associated with down-regulation of METTL3 expression, reduction of RNA m6A methylation, and up-regulation of SIRT1 expression in HSR mice.