右美托咪定对双重打击致大鼠急性肺损伤的影响

Effect of dexmedetomidine on acute lung injury induced by"double hit"in rats

目的评价右美托咪定对双重打击致大鼠急性肺损伤的影响。方法SPF级雄性SD大鼠40只,8周龄,体重215~225 g,采用随机数字表法分为4组(n=10):假手术组(Sham组)、双重打击致急性肺损伤组(ALI组)、双重打击致急性肺损伤+右美托咪定组(ALI+Dex组)和双重打击致急性肺损伤+右美托咪定+育亨宾组(ALI+Dex+Y组)。ALI组、ALI+Dex组和ALI+Dex+Y组通过胸部撞击-失血性休克复苏建立双重打击致急性肺损伤模型。ALI+Dex组胸部撞击后即刻静脉输注右美托咪定负荷剂量1μg·kg^-1·h^-1持续10 min,随后调整剂量至5μg·kg^-1·h^-1至实验结束,ALI+Dex+Y组分别在给予右美托咪定负荷剂量后及胸部撞击3 h后经静脉注射育亨宾0.1 mg/kg。模型制备成功后6 h处死大鼠并留取血标本,采用ELISA法检测血清TNF-α和IL-6浓度;取肺组织,计算湿重/干重(W/D)比值,并进行肺组织损伤评分;采用SABC法检测Fas、FasL和caspase-3表达水平;采用TUNEL法计算肺组织细胞凋亡指数(AI);分别采用硫代巴比妥酸法和黄嘌呤氧化酶法检测MDA含量及SOD活性。结果与Sham组比较,ALI组肺损伤评分、AI、肺组织Fas、FasL、caspase-3和MDA水平、血清TNF-α和IL-6浓度升高,肺组织SOD活性降低(P<0.05);与ALI组比较,ALI+Dex组及ALI+Dex+Y组肺损伤评分、AI、肺组织Fas、FasL、caspase-3和MDA水平、血清TNF-α和IL-6浓度降低,肺组织SOD活性升高(P<0.05);与ALI+Dex组比较,ALI+Dex+Y组肺损伤评分、AI、肺组织Fas、FasL、caspase-3和MDA水平、血清TNF-α和IL-6浓度升高,肺组织SOD活性降低(P<0.05)。结论右美托咪定可减轻双重打击致大鼠急性肺损伤,部分机制可能与激活α2肾上腺素能受体,抑制炎症反应、脂质过氧化反应及细胞凋亡有关。

Objective To evaluate the effect of dexmedetomidine on acute lung injury(ALI)induced by"double hit"in rats.Methods Forty SPF male Sprague-Dawley rats,aged 8 weeks,weighing 215-225 g,were divided into 4 groups(n=10 each)using a random number table method:sham operation group(Sham group),"double hit"-induced ALI group(ALI group),"double hit"-induced ALI plus dexmedetomidine group(ALI+Dex group)and"double hit"-induced ALI plus dexmedetomidine plus yohimbine group(ALI+Dex+Y group).ALI was induced by blunt chest trauma and hemorrhagic shock-resuscitation in pentobarbital sodium-anesthetized rats in ALI,ALI+Dex and ALI+Dex+Y groups.In group ALI+Dex,dexmedetomidine was intravenously infused for 10 min in a loading dose of 1μg·kg^-1·h^-1 starting from the time point immediately after blunt chest trauma,followed by continuous infusion of 5μg·kg^-1·h^-1 until the end of operation.Yohimbine 0.1 mg/kg was injected after giving the loading dose of dexmedetomidine and at 3 h after blunt chest trauma in ALI+Dex+Y group.Rats were sacrificed at 6 h after successful establishment of the model,blood samples were obtained for determination of concentrations of TNF-αand IL-6 in serum(by enzyme-linked immunosorbent assay),and lung tissues were obtained for determination of wet/dry weight(W/D)ratio,expression of Fas,FasL and caspase-3 in lung tissues(by SABC assay),cell apoptosis(by TUNEL),content of malondialdehyde(MDA)and activity of superoxide dismutase(SOD)and for examination of the pathological changes which were scored.The apoptosis index(AI)was calculated.Results Compared with Sham group,the lung injury score,AI,levels of Fas,FasL,caspase-3 and MDA,and concentrations of TNF-αand IL-6 in serum were significantly increased,and the SOD activity in lung tissues was decreased in ALI group(P<0.05).Compared with ALI group,the lung injury score,AI,levels of Fas,FasL,caspase-3 and MDA,and concentrations of TNF-αand IL-6 in serum were significantly decreased,and the SOD activity in lung tissues was increased in ALI+Dex and ALI+Dex+Y groups(P<0.05).Compared with group ALI+Dex,the lung injury score,AI,levels of Fas,FasL,caspase-3 and MDA,and concentrations of TNF-αand IL-6 in serum were significantly increased,and the SOD activity in lung tissues was decreased in group ALI+Dex+Y(P<0.05).Conclusion Dexmedetomidine reduces ALI induced by"double hit"in rats,and the mechanism may be partially related to activating alpha-2 adrenergic receptor and inhibiting inflammatory responses,lipid peroxidation and cell apoptosis.