维生素A对大鼠实验性肺气肿肺泡壁细胞增殖与凋亡的影响

Effects of vitamin A on the proliferation and apoptosis of alveolar cells of experimental emphysema in rats

目的观察维生素A对大鼠实验性肺气肿的干预作用，探讨其对肺泡壁细胞增殖和凋亡的影响。方法雄性Wistar大鼠24只，采用随机数字表法分为对照组、模型组和维生素A组，每组8只。模型组、维生素A组在实验之初采用气管内滴入2kU／kg弹性蛋白酶复制肺气肿模型，对照组气管内滴入等量生理盐水，术后第5周起进行药物干预，维生素A组每天给予100kU／kg维生素A灌胃，其他两组给予等量油剂，共进行4周。实验第8周后处死大鼠。行HE染色观察各组大鼠肺泡的病理学变化，免疫组织化学法观察增殖细胞核抗原（PCNA）的表达，末端脱氧核酸转移酶介导的dUTP缺口末端标记（TUNEL）法观察肺泡壁细胞的凋亡。统计学处理采用单因素方差分析，多组间两两比较采用LSD法。结果模型组平均肺泡数（43±11）明显低于对照组（101±15）和维生素A组（56±8）；平均肺泡面积[（3763±504）μm^2]明显高于对照组[（1919±270）μm^2]和维生素A组[（2710±276）μm^2]；增殖指数[（30．7±7．6）％]明显高于对照组[（9．9±1．8）％]，明显低于维生素A组[（45．4±5．0）％]；凋亡指数[（22．0±4．6）％]明显高于对照组[（9．8±1．7）％]和维生素A组[（17．3±3．5）％]；增殖指数／凋亡指数（1．03±0．19）与对照组（1．45±0．52）无明显差别，明显低于维生素A组（2．73±0．64）。结论维生素A能促进弹性蛋白酶诱导大鼠实验性肺气肿的肺泡壁细胞增殖并抑制其凋亡，使肺泡壁细胞增殖／凋亡的平衡向增殖倾斜，从而对大鼠实验性肺气肿起到一定的改善作用。

Objective To study the effect of vitamin A on experimental emphysema in rats, and on the proliferation and apoptosis of the alveolar cells. Methods Twenty-four Wistar rats were randomly divided into 3 groups ： a control group （ C ）, an emphysema model group （ M ） and a vitamin A treatment emphysema group （V） , with 8 rats in each group. Experimental emphysema was induced by instilling elastase into the lungs of the rats in group M and group V. Vitamin A injection via esophagus was given from the 5th week to the 8th week after elastase instillation. At the end of 8th week, the lungs of the rats were extracted and fixed. The pathological sections were observed by HE staining. The proliferating cell nuclear antigen （PCNA） was examined by immunohistochemical method. The apoptosis of the alveolar cells was observed by the method of terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling （TUNEL）. Results The mean alveolar number （MAN） in the rats of group M （43 ±11 ） was significantly lower than those in the rats of group C （101 ± 15） and group V （56 ±8）. The mean alveolar area （MAA） in the rats of group M [ （ 3763 ± 504 ） μm^2 ] was significantly higher than those in the rats of group C [ （ 1919 ± 270） μm^2] and group V [ （2710 ± 276） μm^2 ]. The proliferation index （PI） in the rats of group M [ （30. 7 ± 7.6） % ] was significantly higher than that in the rats of group C [ （ 9.9 ± 1.8 ） % ] but was significantly lower than that in the rats of group V [ （17. 3 ± 3.5）% ]. The apoptosis index （AI） in the rats of group M [ （ 22. 0 ± 4. 6） % ] was significantly higher than those in the rats of group C [ （ 9. 8 ± 1.7 ） % ] and group V [ （ 17.3 ± 3.5 ） % ]. PI/AI in the rats of group M （ 1.03 ± 0. 19 ） showed no difference compared to that in the rats of group C （ 1.45 ± 0. 52）, but was lower than that in the rats of group V （2. 73 ± 0. 64）. Conclusion Vitamin A was demonstrated to promote the proliferation of the alveolar cells and inhibit their apoptosis in experimental emphysema of rats, and hence contribute to the improvement of emphysema.