不同营养支持途径对烧伤大鼠肠粘膜上皮细胞周期的影响

目的：探讨肠道喂养及静脉营养对烧伤早期肠粘膜上皮细胞周期的影响。方法：66只烧伤大鼠随机分为肠道喂养组（EF组）及静脉营养组（PN组），分别采用灌喂和颈外静脉输入方法给予等氮、等热卡的营养液。每组设伤后6、12、24、48、72h5个观察时相点，每时相点6只大鼠，并设正常对照（6只）。采用流式细胞技术进行空、回肠粘膜上皮细胞周期分析，以Western blot法检测肠粘膜细胞周期蛋白D1、E及细胞周期蛋白依赖性激酶（CDK）2、4的表达。结果：（1）肠粘膜上皮GO／G1期细胞百分比的变化：在空肠粘膜，伤后72h时EF组明显低于PN组（P＜0．05）；在回肠粘膜，6、12、48、72h时EF组与PN组比较，差异有显性意义（P＜0．05）；（2）伤后48．72h时EF组S期细胞百分比均显高于PN组（P＜0．05－0．01）；（3）肠粘膜细胞周期蛋白D1表达的变化：与对照值比较，EF组在伤后24h及PN组在伤后48h明显增高（P＜0．05），72h时EF组显高于PN组（P＜0．05）；（4）EF组肠粘膜细胞周期蛋白E的表达在伤后72h显高于对照值和PN组（P＜0．05）；（5）PN、EF组肠粘膜CDK2的表达与对照值比较以及PN、EF两组间比较，差异均无显性意义（P＞0．05），EF组CDK4的表达在72h明显增高（P＜0．05）。结论：烧伤后早期肠道喂养能加速肠粘膜上皮细胞周期的进程以及受损肠粘膜的修复与更新。细胞周期蛋白及CDK在其中起重要作用。

The injury and Maintenance of postburn intestinal barrier The influence of different nutritional support routes on the intestinal mucosal epithelial cell cycle in burned rats

OBJECTIVE: To explore the influence of different nutritional support routes on the intestinal mucosal epithelial cell cycle in burned rats. METHODS: Sixty-six Wistar rats inflicted with 30% TBSA III degree burns on the back were employed as the model and were randomly divided into enteral feeding group (EF) and intravenously parenteral nutrition group (PN). Equal volume of nutritional support fluid containing predetermined equal amount of calories and nitrogen was applied via feeding or intravenously infusion through external jugular vein. The indices were observed on 6, 12, 24, 48 and 72 postburn hours (PBHs) with the reference to those in 6 normal rats. The intestinal epithelial cell cycle in jejunal and ileal mucous membrane was analyzed by flow cytometry. Western blotting method was employed in the examination of the expression of cyclin D1, E and that of cyclin dependent kinase (CDK)2 and CDK4. RESULTS: (1) lntestinal mucosal epithelial G0/G1 ratio in jejunum in EF group was significantly lower than that in PN group at 72 PBHs (P < 0.05). While the ratio in ileum in EF was obviously higher than that in PN groups at 6, 12, 48 and 72 PBHs (P < 0.05). (2) The cell percentage of S phase in EF group was evidently higher than that in PN group (P < 0.05 - 0.01) at 48 and 72 PBHs. (3) Intestinal mucosal cyclin D1 expression increased significantly in EF group at 24 PBHs and in PN group at 48 PBHs (P < 0.05) and which in EF group was obviously higher than that in PN group at 72 PBHs (P < 0.05). (4) The expression of the intestinal mucosal cyclin E in EF group at 72 PBHs was evidently higher than the control value and that in PN group (P < 0.05). (5) The expression of CDK2 exhibited no obvious difference among PN,EF and control group (P < 0.05). The CDK4 expression in EF group increased obviously at 72 PBHs (P < 0.05). CONCLUSION: Early postburn enteral feeding was beneficial to the progression of intestinal mucosal epithelial cell cycle and to the repairing and renovation of injured intestinal mucosal membrane. Cyclin and CDK might be important in the modulation of the intestinal mucosal epithelial cell cycle.