低氧因素对丙泊酚麻醉新生大鼠认知功能的影响

Effect of hypoxic factors on cognitive function in propofol-anesthetized neonatal rats

目的研究低氧因素对丙泊酚麻醉新生大鼠认知功能的影响。方法用随机数表法将新生7 d的SD大鼠分为6组,每组18只:氧气对照组(CO)、空气对照组(CA)、低氧对照组(CH)和丙泊酚氧气组(PO)、丙泊酚空气组(PA)、丙泊酚低氧组(PH)。丙泊酚组腹腔注射丙泊酚50 mg·kg^(-1),对照组腹腔注射脂肪乳5.0 mL·kg^(-1),1次/天,连续7 d。每次注射完毕后,将大鼠分别放置于轻度低氧(18%O_2)、空气(21%O_2)和氧气(50%O_2)环境中,监测血氧饱和度(SpO_2)。Mirros水迷宫实验检测各组大鼠学习记忆能力;免疫组化法检测各组海马CA1区活化型半胱氨酸天冬氨酸蛋白酶-3(Cleaved-caspase-3)表达和蛋白激酶B(Akt)、糖原合成酶激酶3β(GSK-3β)及磷酸化蛋白的表达。结果对照组(CO组、CA组、CH组)和丙泊酚组(PO组、PA组、PH组)的SpO_2分别为(98.4±0.5)%,(98.4±0.8)%,(97.5±0.6)%,(98.5±0.4)%,(82.4±1.7),(68.8±3.0)%,PA组和PH组与对照组比较,SpO_2显著降低,差异均有统计学意义(均P<0.01)。PA组、PH组与对照组比较,逃逸潜伏期延长,差异均有统计学意义(均P<0.05)。这6组的海马CA1区Cleaved-caspase-3积分光密度(IOD)值分别为103.60±46.57,83.20±38.78,123.80±78.60,591.00±316.30,1083.67±421.50,2873.60±391.49,PA组和PH组与对照组比较,IOD值明显升高,差异均有统计学意义(均P<0.05)。这6组的P-Akt/Akt灰度值比值分别为1.20±0.15,1.43±0.16,1.53±0.13,0.89±0.17,0.66±0.10,0.50±0.12,PA组和PH组与对照组比较,差异均有统计学意义(均P<0.01)。结论低氧因素显著增加丙泊酚麻醉的神经毒性,其机制可能与抑制P-Akt及GSK-3β表达增加有关。

Objective To investigate the effects of hypoxic factors on cognitive function in propofol-anesthetized neonatal rats. Methods A total of 108 seven-day old Sprague Dawley（ SD） rats were assigned into six groups： lipide mulsion solvent ＋ 50% oxygen（ CO）,lipid emulsion solvent ＋ air（ CA）,lipid emulsion solvent ＋ 18% oxygen（ CH）,propofol ＋ 50% oxygen（ PO）,propofol ＋ air（ PA）,propofol ＋ 18%oxygen（ PH）. Propofol（ 50 mg·kg^-1） or lipid emulsion solvent（ 5. 0 mL·kg^-1） was intraperiotoneally administered to seven-day-old SD rats one time each day for seven consecutive days. The pulse oxygen saturation（ SpO2） were monitored after administration. The rats were returned to the cage after recovery of right reflex. Learning and memory functions were assessed using Morris water maze at 28 days old of rats.Immunohistochemistry method was used to detect the expression of Cleaved-cysteinyl aspartate specific protease-3（ Cleaved-caspase-3） in hippocampus CA1 region. Protein kinase B phosphorylation（ P-Akt）,protein kinase B（ Akt）,glycogen synthase kinase-3β phosphorylation（ P-GSK-3β）,glycogen synthase kinase-3β（ GSK-3β）proteins were detected by Western blotting in the hippocampus at the end of exposure. Results The SpO2（ %） in control groups（ CO group, CA group, CH group） and propofol groups（ PO group,PA group,PH group） were（ 98. 4 ± 0. 5） %,（ 98. 4 ± 0. 8） %,（ 97. 5 ± 0. 6） %,（ 98. 5 ± 0. 4） %,（ 82. 4 ± 1. 7）,（ 68. 8 ± 3. 0） %,respectively;the difference betweent PA group and PH group with control groups were significantly（ all P〈0. 01）. Compared with the control groups,the escape latency of the PA group and PH group prolonged with significantly（ all P〈0. 05）. The integrated optical density（ IOD） values of Cleaved-caspase-3 of the hippocampal CA1 region in the 6 groups were103. 60 ± 46. 57,83. 20 ± 38. 78,123. 80 ± 78. 60,591. 00 ± 316. 30,1083. 67 ± 421. 50,2873. 60 ± 391. 49,respectively; the differences of the IOD values in the PA and PH groups were significantly higher than in control groups（ all P〈0. 05）. The expression of P-Akt/Akt in hippocampus of the 6 groups were 1. 20 ± 0. 15,1. 43 ± 0. 16,1. 53 ± 0. 13,0. 89 ± 0. 17,0. 66 ± 0. 10,0. 50 ± 0. 12,respectively; the expression of P-Akt/Akt in the PA and PH groups was significantly lower than in control groups（ all P〈0. 01）. Conclusion Hypoxia significantly increased the neurotoxicity of propofol anesthesia,the mechanism may be related to the inhibition of phospho-Akt and increased GSK-3 beta expression.