电针对内毒素性急性肺损伤大鼠肺组织内质网应激的影响

Effect of electroacupuncture on endoplasmic reticulum stress in lung tissues of rats with acute lung injury induced by endotoxin

目的评价电针对内毒素性急性肺损伤大鼠肺组织内质网应激的影响。方法健康清洁级雄性sD大鼠40只，8周龄，体重180～210g，采用随机数字表法分为4组（n=10）：对照组（C组）、急性肺损伤组（AL1组）、电针组（E组）和非穴位电针组（NE组）。采用静脉注射脂多糖5mg／kg的方法制备内毒素性急性肺损伤模型。E组于模型制备前1—4d及模型制备过程中电针足三里穴及内关穴（疏密波频率2／15Hz，波宽0．2～0．6ms，刺激电流1～2mA，刺激强度以大鼠肢体出现轻微颤动为宜），刺激时间9：30-10：30，30min／次，1次／d，NE组以相同的参数电针刺激足三里穴及内关穴旁开0．5cm非经非穴处。静脉注射脂多糖后6h时，处死动物，取肺组织，行肺损伤评分，确定湿重／干重比值（W／D比值），采用TUNEL法确定肺泡上皮细胞凋亡指数（AI），采用Westernblot法检测肺组织葡萄糖调节蛋白78（GRP78）、CCAAT／增强子结合蛋白同源蛋白（CHOP）及caspase-12表达水平。结果与C组比较，其余3组肺损伤评分、W／D比值及肺泡上皮细胞AI升高，肺组织GRP78、CHOP及easpase-12表达上调（P〈0．05）；与ALI组比较，E组肺损伤评分、W／D比值及肺泡上皮细胞AI降低，肺组织GRP78、CHOP及caspase．12表达下调（尸〈0．05），NE组上述指标差异无统计学意义（P〉0．05）。结论电针减轻大鼠内毒素性急性肺损伤的机制与抑制肺组织内质网应激，减轻肺泡上皮细胞凋亡有关。

Objective To evaluate the effect of electroacupuncture on endoplasmic reticulum stress in lung tissues of rats with acute lung injury （ALI） induced by endotoxin. Methods Forty healthy patho- gen-free male Sprague-Dawley rats, aged 8 weeks, weighing 180-210 g, were divided into 4 groups （n= 10 each） using a random number table： control group （group C） , ALI group, electroacupuneture group （group E） , and eleetroaeupuncture at non-acupoint group （group NE）. Lipopolysaecharide 5 mg/kg （in 0.5 ml normal saline） was injected intravenously to establish the model of endotoxin-induced ALI. Bilateral 30 min eleetroaeupuncture stimulation of Zusanli and Neiguan aeupoints was performed with the disperse- dense wave （frequency 2/15 Hz, wave length 0.2-0.6 ms, intensity 1-2 mA） once a day （time for stim- ulation 9：30--10：30） for 4 consecutive days before and during establishment of the model in group E. Electroacupuncture was performed with the same parameters at the points 0.5 cm lateral to the aeupoints of Zusanli and Neiguan in group NE. At 6 h after lipopolysaceharide injection, the rats were sacrificed, and lungs were removed for microscopic examination and for determination of wet to dry weight ratio （W/D ratio） , apoptosis in alveolar epithelial cells and expression of glucose-regulated protein 78 （GRP78） andCCAAT/enhancer-binding protein homologous protein （CHOP） and caspase-12 in lung tissues （by Western blot）. The pathological changes of lungs were scored. Apoptosis index （AI） was calculated. Results Compared with group C, lung injury scores, W/D ratio and AI were significantly increased, and the expression of GRP78, CHOP and caspase-12 in lung tissues was up-regulated in the other three groups （P〈0.05）. Compared with group ALl, lung injury scores, W/D ratio and AI were significantly decreased, and the expression of GRP78, CHOP and caspase-12 in lung tissues was down-regulated in group E （P〈 0.05） , and no significant change was found in the parameters mentioned above in group NE （P〉0.05）. Conclusion The mechanism by which electroacupunctnre attenuates endotoxin-indueed ALl is related to inhibition of endoplasmic reticulum stress and reduction of apoptosis in alveolar epithelial cells in rats.