活化α7烟碱型乙酰胆碱受体对呼吸机相关肺损伤模型大鼠的保护机制研究

Protective effect of activation of α7 nicotinic acetylcholine receptor on ventilator-induced lung injury in rats

目的评价激活α7烟碱型乙酰胆碱受体对大鼠呼吸机相关肺损伤的影响。方法采用随机数字法将32只雄性Sprague Dawley大鼠分为:对照组(C组)、机械通气组(V组)、烟碱预处理+机械通气组(N组)、甲基牛扁碱(MLA)+烟碱+机械通气组(MLA组),每组8只。C组大鼠气管插管后不进行机械通气,保留自主呼吸,其余各组大鼠机械通气2 h。N组大鼠在机械通气前30 min腹腔注射1 mg/kg的烟碱;MLA组大鼠在腹腔注射烟碱前30 min先腹腔注射1 mg/kg的MLA,其余各组大鼠腹腔注射等量等渗NaCl溶液。机械通气结束后即刻处死大鼠,计算各组大鼠肺组织湿重/干重、苏木素-伊红(HE)染色、肺组织损伤病理学评分,并采用Western-blotting检测白细胞介素1β(IL-1β)、IL-6、肿瘤坏死因子α(TNF-α)蛋白表达水平。结果 C组大鼠肺泡形态结构正常;V组大鼠肺泡形态结构破坏,大量炎症细胞浸润;N组大鼠肺泡形态结构稍破坏,少量炎症细胞浸润;MLA组大鼠肺泡形态结构破坏,肺泡萎陷,较多炎症细胞浸润。4组大鼠肺组织湿重/干重、损伤评分、IL-1β、IL-6及TNF-α蛋白表达水平比较,差异均有统计学意义(F=168.009、647.579、138.005、192.706、178.094,P均<0.05)。进一步两两比较发现,V组大鼠肺组织湿重/干重、损伤评分、IL-1β、IL-6、TNF-α蛋白表达水平均较C组更高(P均<0.05);N组大鼠湿重/干重、损伤评分、IL-1β、IL-6、TNF-α蛋白表达水平均较V组明显降低(P均<0.05);MLA组大鼠肺组织湿重/干重、损伤评分、IL-1β、IL-6、TNF-α蛋白表达水平均较N组明显升高,差异有统计学意义(P均<0.05)。结论烟碱对呼吸机相关肺损伤的大鼠模型具有保护作用,其机制与激活α7-nAChR有关。

Objective To evaluate the activation effect of α7 nicotinic acetylcholinereceptor （α7-nAChR） on ventilator-induced lung injury in rats. Methods Thirty-two male Sprague Dawley rats were randomly divided into four groups： the control group （C group）,mechanical ventilation group （V group）, nicotine pretreatment and mechanical ventilation group （N group）, and methylbovine （MLA）, nicotine and ventilation group （MLA group）, with 8 rats in each group. Rats in the C group did not undergo mechanical ventilation after tracheal intubation, while the rest were mechanically ventilated for 2 hours. Rats in the N group were intraperitoneally injected with 1 mg / kg nicotine 30 min before mechanical ventilation, rats in MLA group were injected with 1 mg / kg MLA 30 min before intraperitoneal injection of niacin, and rats in other groups were intraperitoneally injected with isotonic sodium chlorrde solution. Rats were sacrificed immediately after mechanical ventilation. The wet / dry weight of lung tissue, hematoxylin eosin （HE） staining and pathological score of lung injury were calculated. The expression levels of nterleukin-1beta （IL-1β）, IL-6, and tumor necrosis factor-alpha （TNF-α） protein were detected by Western-blotting. Results The alveolar morphology of rats was normal in the C group; alveolar morphology was destroyed, and a large number of inflammatory cells infiltrated in V group. The alveolar morphology was slightly destroyed, and a small number of inflammatory cells infiltrated in N group. The alveolar structure was destroyed, alveolus collapsed, and more inflammatory cells infiltrated in MLA group. There were significant differences in the wet / dry weight, injury score, and expressions of IL-1β, IL-6 and TNF-α protein of lung tissue among these four groups （F = 168.009, 647.579, 138.005, 192.706, 178.094; all P 〈 0.05）. Further comparison showed that the wet / dry weight, injury score, and expressions of IL-1β, IL-6 and TNF-α protein of lung tissue were significantly higher in the V group than in C group （all P 〈 0.05）, significantly lower in N group than in V group （all P 〈 0.05）, and significantly higher in MLA group than in N group （all P 〈 0.05）. Conclusion Nicotine has a protective effect on ventilator-induced lung injury in rats, and its mechanism is related to the activation of α7-nAChR.