海马nNOS-PSD95耦合在七氟醚诱发小鼠短期记忆提取障碍中的作用

Role of hippocampal nNOS-PSD95 coupling in short-term memory retrieval disorder induced by sevoflurane in mice

目的评价海马神经型一氧化氮合酶(nNOS)-突触后致密蛋白95(PSD95)耦合在七氟醚诱发小鼠短期记忆提取障碍中的作用。方法清洁级健康成年昆明种小鼠16只,雌雄不拘,2~3月龄,体重30~35 g,按随机数字表法分为2组(n=8):七氟醚组(S组)和nNOs-PSD95解耦合剂ZL006组(Z组)。成功建立避暗记忆后,2组均吸入3.3%七氟醚及40%O22 h,麻醉前半小时S组腹腔注射生理盐水1.5 ml,Z组腹腔注射ZL0061 mg/kg。于麻醉前和麻醉结束后12 h时记录步入潜伏期和错误次数。随后处死小鼠取海马组织,采用Western blot法检测海马nNOS和PSD95的表达水平,采用免疫共沉淀法检测海马nNOS-PSD95共表达水平。结果与麻醉前比较,麻醉结束后12 h时S组步入潜伏期缩短,错误次数增多(P<0.05),Z组上述指标差异无统计学意义(P>0.05)。与S组比较,Z组麻醉结束后12 h时步入潜伏期延长,错误次数减少,nNOS-PSD95共表达下调(P<0.05),nNOS和PSD95表达差异无统计学意义(P>0.05)。结论七氟醚诱发小鼠短期记忆提取障碍的机制可能与促进海马nNOS-PSD95耦合有关。

Objective To evaluate the role of hippocampal neuronal nitric oxide synthase(nNOS)-postsynaptic dense protein 95(PSD95)coupling in short-term memory retrieval disorder induced by sevoflurane in mice.Methods Sixteen clean-grade healthy Kunming mice of both sexes,aged 2-3 months,weighing 30-35 g,were divided into 2 groups(n=8 each)according to the random number table method:sevoflurane group(S group)and nNOS-PSD95 uncoupling agent ZL006 group(Z group).After successful establishment of dark avoidance memory,3.3%sevoflurane and 40%O2 were inhaled for 2 h in both groups,and normal saline 1.5 ml was intraperitoneally injected in group S and ZL0061 mg/kg in group Z at 30 min before anesthesia.The step-through latency and error times were recorded before anesthesia and at 12 h after the end of anesthesia.The mice were then sacrificed,and hippocampal tissues were taken for determination of the expression of nNOS and PSD95(by Western blot)and co-expression of nNOS and PSD95(by immunoprecipitation).Results Compared with that before anesthesia,the step-through latency was significantly shortened,and the error times were increased at 12 h after anesthesia in group S(P<0.05),and no significant change was found in the above indicators in group Z(P>0.05).Compared with group S,the step-through latency was significantly prolonged,error times were decreased,the co-expression of nNOS and PSD95 was down-regulated(P<0.05),and no significant change was found in the expression of nNOS and PSD95 in group Z(P>0.05).Conclusion The mechanism by which sevoflurane induces short-term memory retrieval disorder may be related to promoting the coupling of nNOS to PSD95 in the hippocampus of mice.