目的 探討七氟醚對(duì)幼齡大鼠學(xué)習(xí)記憶功能的影響及機(jī)制。方法 48只幼鼠隨機(jī)分為對(duì)照組、七氟醚-1 h組、七氟醚-3 h組與七氟醚-3 h＋雷帕霉素（20 mg/kg，于麻醉前連續(xù)ip 3 d）組，每組12只。麻醉當(dāng)天，對(duì)照組幼鼠吸入氧氣混合氮?dú)? h，七氟醚組以含3%七氟醚的混合氣體麻醉1 h或3 h。4周后，應(yīng)用Morris水迷宮檢測(cè)幼鼠學(xué)習(xí)與記憶功能；使用電子透射顯微鏡觀察神經(jīng)元自噬；采用BrdU免疫熒光法觀察幼鼠海馬組織中神經(jīng)元新生；Western blotting法檢測(cè)幼鼠海馬組織中NeuN、DCX、PI3K、mTOR、LC3-II/LC3-I和Beclin-1蛋白表達(dá)。結(jié)果 與對(duì)照組比較，七氟醚-3 h組幼鼠逃避潛伏期顯著增加（P<0.05），穿越平臺(tái)次數(shù)顯著減少（P<0.05），靶象限停留時(shí)間顯著減少（P<0.05）；與七氟醚-3 h組比較，雷帕霉素顯著縮短幼鼠逃避潛伏期（P<0.05），增加測(cè)試中穿越平臺(tái)次數(shù)（P<0.05）與靶象限停留時(shí)間（P<0.05）。與對(duì)照組比較，七氟醚-3 h組幼鼠齒狀回中神經(jīng)元新生顯著減少（P<0.05），神經(jīng)元新生相關(guān)蛋白NeuN與DCX表達(dá)顯著降低（P<0.05）；海馬組織中PI3K表達(dá)顯著降低（P<0.05），且mTOR蛋白表達(dá)顯著增加（P<0.05），而LC3-II/LC3-I與Beclin-1表達(dá)顯著下調(diào)（P<0.05），造成自噬小體顯著減少（P<0.05）。與七氟醚-3 h組比較，雷帕霉素顯著增加NeuN與DCX蛋白表達(dá)（P<0.05），顯著提高PI3K蛋白表達(dá)（P<0.05），顯著下調(diào)mTOR表達(dá)（P<0.05），顯著上調(diào)LC3-II/LC3-I與Beclin-1表達(dá)（P<0.05），顯著增加自噬小體的形成。結(jié)論 七氟醚通過下調(diào)PI3K，增加mTOR表達(dá)，抑制LC3-II/LC3-I與Beclin-1表達(dá)，減少自噬小體形成并抑制神經(jīng)元新生，最終誘導(dǎo)幼鼠學(xué)習(xí)和記憶功能障礙。

Objective To investigate the effect and mechanism of sevoflurane on the learning and memory function in newborn rats. Methods 48 young rats were randomly divided into control group, sevoflurane-1 h group, sevoflurane-3 h group and sevoflurane-3 h+ rapamycin group, with 12 rats in each group. Before anesthesia, rats in each group were intraperitoneally injected with saline or rapamycin (20 mg/kg) for three days. On the day of anesthesia, the newborn rats in control group were inhaled with oxygen and nitrogen for three hours, and the newborn rat in sevoflurane group were anesthetized with 3% sevoflurane for one or three h. Morris water maze was used to detect the learning and memory function of young mice after four weeks. Transmission electron microscope was applied for observation of autophagosome. In addition, Immunofluorescence and Western blotting were used to explore the expression of neuron regeneration and autophagy-related proteins in the hippocampus of newborn mice. Results Compared with control group, sevoflurane increased the escape latency of newborn rats (P < 0.05), decreased the number of crossing platforms (P < 0.05), and reduced the residence time in the target quadrant (P < 0.05). However, the intervention of rapamycin significantly reduced the escape latency of young mice (P < 0.05), increased the number of platform crossings (P < 0.05) and the target quadrant stay time (P < 0.05). In addition, sevoflurane caused decreased neurogenesis in the dentate gyrus of newborn rats, and inhibited the expression of neuron regeneration-related proteins NeuN and DCX. At the same time, sevoflurane mediated the decrease of PI3K expression in the hippocampus of newborn rats (P < 0.05), and caused an increase in mTOR protein expression (P < 0.05), while the expression of LC3-II/LC3-I and Beclin-1 was significantly down-regulated (P < 0.05), resulting in a decrease in autophagosome (P < 0.05). However, the administration of autophagy inducer rapamycin significantly increased the expression of PI3K (P < 0.05), downregulated the expression of mTOR (P<0.05), and up-regulated the expression of LC3-II/LC3-I and Beclin-1 (P < 0.05) which increased the formation of autophagosome. Conclusion Sevoflurane mediates down-regulation of PI3K, up-regulation of mTOR, inhibition of LC3-II/LC3-I and Beclin-1, to reduce formation of autophagosomes and inhibit neurogenesis, which ultimately induces learning and memory dysfunction in newborn rats.

R965.3

河北省重點(diǎn)研發(fā)計(jì)劃項(xiàng)目（182777195）