脑摄取平衡时丙泊酚对犬脑不同区域兴奋性氨基酸转运体2mRNA的影响

Effect of propofol at uptake equilibrium on excitatory amino acid transporter-2 mRNA expression in different brain regions in dogs

目的:探讨丙泊酚对犬脑不同区域兴奋性氨基酸转运体2(EAAT2)mRNA表达的影响。方法:18只健康杂种犬,雌雄不限,12～18个月,体重10～12kg,随机分为对照组(C组)、低剂量组(L组)和高剂量组(H组),每组6只。L组15s内静脉注入丙泊酚5.5mg/kg诱导,55mg/(kg.h)恒速静注维持;H组15s内注入丙泊酚7.0mg/kg诱导,70mg/(kg.h)恒速静注维持。静注50min时取颈内动、静脉血各2mL后静注10%KCl注射液2mg/kg处死L组和H组动物。采用高效液相色谱-紫外法(HPLC-UV)检测动、静脉血浆丙泊酚浓度。C组不给予任何干预措施,快速静注10%KCl2mg/kg处死。3组均于无菌条件下解剖获取下丘脑、底丘脑、背侧丘脑、海马、脑桥、顶叶以及额叶组织,qRT-PCR方法检测脑组织EAAT2 mRNA的表达水平。结果:丙泊酚静注50min时,L组和H组丙泊酚血浆浓度(动脉-动脉,静脉-静脉比较)差异显著(P<0.01),而两组颈内动脉和静脉丙泊酚血浆浓度比较差异均无统计学意义(P>0.05)。下丘脑、海马和顶叶EAAT2 mRNA的相对表达量,在L组和H组均较C组明显升高,差异显著(P<0.05);L组和H组比较差异均无统计学意义(P>0.05)。背侧丘脑等其他脑区EAAT2 mRNA的相对表达量3组之间差异无显著性(P>0.05)。结论:丙泊酚恒速静注50min,犬脑摄取达到平衡状态;此时丙泊酚可显著上调下丘脑、海马和顶叶EAAT2 mRNA的表达,但不同剂量对其表达的影响差异无显著性。

Objective To investigate the effect of propofol at uptake quilibrium on excitatory amino acid transporter-2 （EAAT2） mRNA expression in different brain regions in dogs. Methods Eighteen healthy male and female mongrel dogs, aged 12 - 18 months and weighed 10 - 12 kg, were divided randomly into high dose group （group H）, low dose group （group L） and control group （group C）, each group with 6 dogs. Dogs in group C and group H were anesthetized with propofol at a single bolus （5.5 and 7.0 mg/kg, respectively） in 15 s followed by propofol infusion at a constant rate [55 and 70 mg/（kg ,h）, respectively]. Then, blood samples （2 mL） were taken from the internal carotid artery and jugular vein to measure plasma propofol concentration using high- performance liquid chromatography ultra-violet spectroscopy （HPLC-UV）. Each dog was sacrificed by intravenous injection of 10% KC1 2 mg/kg. The hypothalamus, subthalamus, dorsal thalamus, hippocampus, pons, parietal lobe and frontal lobe were obtained and used to determine EAAT2 mRNA expression by Quantitative Real-time PCR （qRT-PCR）. Results When propofol infusion at a constant rate for 50 min, no significant differences were founct between plasma propofol concentration in internal carotid artery and jugular vein in both group L and group H （P 〉 0.05）. EAAT2 mRNA levels in group L and group H were higher than that in group C （P 〈 0.05） in bypothalamus, hippocampus and parietal lobe, with no significant differences between group L and group H （P 〉 0.05）. No significant differences of EAAT2 mRNA expression were found among the three groups in other brain regions （P 〉 0.05）. Conclusions Brain uptake of propofol reached equilibrium at 50 minutes after propofnl infusion at a constant rate. Propofol could increase EAAT2 mRNA expression significantly at this time point in hypothalamus, hippocampus and parietal lobe, without no significant doses-dependent effects.