右美托咪定对大鼠内毒素性急性肺损伤时细胞焦亡的影响

Effect of dexmedetomidine on pyroptosis in rats with endotoxin-induced acute lung injury

目的评价右美托咪定对大鼠内毒素性急性肺损伤(ALI)时细胞焦亡的影响。方法SPF级雄性SD大鼠60只,6周龄,体重200~220 g,采用随机数字表法分为5组(n=10):对照组(C组)、ALI组和不同剂量右美托咪定组(D1~3组)。ALI组和D1~3组腹腔注射LPS 5 mg/kg制备大鼠内毒素性ALI模型。造模后即刻,D1~3组分别腹腔注射右美托咪定12.5、25.0和50.0μg/kg,C组腹腔注射等容量生理盐水,1次/d,连续14 d。给药结束后,处死大鼠,行肺泡灌洗,收集左支气管肺泡灌洗液,采用ELISA法测定IL-1β、IL-6和TNF-α的浓度;取肺组织,测定湿重/干重(W/D)比值;行HE染色,光镜下观察肺组织病理学结果;采用Western blot法测定肺组织cleaved-caspase-1、消皮素剪切体N端(GSDMD-N)、IL-18和IL-1β的表达水平。结果与C组相比,ALI组和D1~3组肺组织W/D比值升高,肺泡灌洗液IL-1β、IL-6和TNF-α浓度升高,肺组织cleaved-caspase-1、GSDMD-N、IL-1β和IL-18表达上调(P<0.05),肺组织病理学损伤加重;与ALI组相比,D1~3组肺组织W/D比值降低,肺泡灌洗液IL-1β、IL-6和TNF-α浓度降低,肺组织cleaved-caspase-1、GSDMD-N、IL-1β和IL-18表达下调,且呈剂量依赖性(P<0.05),肺组织病理学损伤减轻。结论右美托咪定减轻大鼠内毒素性ALI的机制可能与抑制细胞焦亡,减轻炎症反应有关。

Objective To evaluate the effect of dexmedetomidine on pyroptosis in rats with endotoxin-induced acute lung injury(ALI).Methods Sixty SPF male Sprague-Dawley rats,aged 6 weeks,weighing 200-220 g,were divided into 5 groups(n=10 each)by a random number table method:control group(group C),ALI group and different doses of dexmedetomidine groups(D1-3 groups).In ALI group and D1-3 groups,LPS 5 mg/kg was intraperitoneally injected to establish endotoxin-induced ALI model.Immediately after establishing the model,dexmedetomidine 12.5,25.0 and 50.0μg/kg were intraperitoneally injected in D1-3 groups,and the equal volume of normal saline was intraperitoneally injected in group C,once a day for 14 consecutive days.After the end of administration,the rats were sacrificed,the left bronchus was lavaged,and the left bronchoalveolar lavage fluid(BALF)was collected for determination of the concentrations of interleukin-1beta(IL-1β),IL-6 and tumor necrosis factor-alpha(TNF-α)(by enzyme-linked immunosorbent assay),and the lung tissue was taken for determination of the wet/dry weight ratio(W/D ratio)and expression of cleaved-caspase-1,N-terminal of the spliceosome(GSDMD-N),IL-18 and IL-1β(by Western blot)and for microscopic examination of the pathological changes(with a light microscope).Results Compared with group C,the W/D ratio of lung tissues was significantly increased,the concentrations of IL-1β,IL-6 and TNF-αin BALF were increased,the expression of cleaved-caspase-1,GSDMD-N,IL-1βand IL-18 in lung tissues was up-regulated(P<0.05),and the pathological damage was aggravated in ALI group and D1-3 groups.Compared with group ALI,the W/D ratio of lung tissues was significantly decreased,and the concentrations of IL-1β,IL-6 and TNF-αin BALF were decreased,the expression of cleaved-caspase-1,GSDMD-N,IL-1βand IL-18 in lung tissues was down-regulated in a dose-dependent manner(P<0.05),and the pathological damage was significantly reduced in D1-3 groups.Conclusion The mechanism by which dexmedetomidine attenuates endotoxin-induced ALI may be related to inhibition of pyroptosis and reduction of inflammatory responses in rats.