异丙酚对在体大鼠前额叶皮质细胞外液谷氨酸和γ-氨基丁酸含量的影响

Effect of propofol on glutamate and GABA extracellular levels in rat intact prefrontal cortex

目的观察局部灌注异丙酚对大鼠前额叶皮质细胞外液中谷氨酸和γ-氨基丁酸(GABA)含量的影响。方法选用30只成年雄性大鼠随机分为实验组(n=24)和对照组(n=6),于前额叶皮质处放置微透析探头。实验组以2μl/min灌注含不同浓度异丙酚(按照异丙酚浓度分为1、3、10、30μmol/L4个亚组,每组n=6)的人工脑脊液;对照组灌流液中不含异丙酚。每10 min收集灌流液并应用反相高效液相色谱法测定其中谷氨酸和GABA浓度。结果局部灌注异丙酚1μmol/L10 min后,各时点灌流液中谷氨酸含量与基础值比较差异无统计学意义(P>0.05)。异丙酚3μmol/L局部灌注后,灌流液中谷氨酸含量于第10、20 min时降至基础值的60%(P<0.05),随后逐渐回升至基础值水平。前额叶皮质局部灌注异丙酚10μmol/L 10 min后,灌流液中谷氨酸含量于第10 min至30 min显著低于基础值(P<0.01或<0.05)。局部灌注异丙酚30μmol/L10 min后,灌流液中谷氨酸含量于第10 min至40 min均显著降低(P<0.01或<0.05)。而不同浓度的异丙酚局部灌注后,各时点灌流液中GABA含量与各基础值比较差异无统计学意义(P>0.05)。结论异丙酚可降低大鼠前额叶皮质细胞外液谷氨酸含量,而对GABA含量不产生影响。

Objective To investigate the effect of propofol locally perfused into the rat prefrontal cortex （PFC） on glutamate and GABA extracellular levels. Methods Thirty male adult rats were randomly divided into 4 groups： test groups and 1 control group （n=6 each）, with a microdialysis probe inserted into the PFC. In the test groups, artificial cerebrospinal fluid （aCSF） containing different concentrations of propofol （ 1, 3, 10 and 30μmol/L respectively） was perfused into the PFC at 2 μl/min; in the control group, only aCSF was infused. The perfusate was collected every 10 rain throughout the experiment to measure the concentrations of glutamate and GABA in the perfusate by reversed-phase high performance liquid chromatography. Results The glutamate level in the perfusate was not changed when propofol was 1 μmol/L （P 〉 0.05 ）, but it decreased significantly for 10 and 20 min when propofol was 3 μmol/L （P 〈 0.05 ）. As the concentration of propofol was further increased （ to 10 and 30 μmol/L） the depression of glutamate level would extend to 40 rain （ P 〈 0.01 or 0.05 ）. However,. the GABA level in the perfusate was not altered throughout the perfusion with different concentrations of propofol （P 〉 0.05）. Conclusion Propofol reduces the glutamate extracellular level in rat intact prefrontal cortex, but has no effect on the GABA level.