烫伤大鼠延迟复苏后肠道防御素-5 mRNA表达变化

CHANGES IN THE EXPRESSION OF RD-5 mRNA IN THE INTESTINE OF SCALDED RATS AFTER DELAYED FLUID RESUSCITATION

目的 探讨烧伤后延迟复苏诱导肠道细菌移位是否与肠道黏膜内帕内特细胞受损、防御素产生减少有关。方法 SPF级Wistar大鼠 5 6只 ,分为 3组 :对照组 (n =8) ;早期复苏组 (n=2 4 ) ,30 %Ⅲ度烫伤后即刻复苏 ;延迟复苏组 (n =2 4 ) ,烫伤后 6h复苏。观察回肠黏膜防御素 5 (RD 5 )mRNA表达、帕内特细胞形态学改变及肠系膜淋巴结 (MLN)、肝、脾、肺细菌移位情况。结果 早期复苏组和延迟复苏组RD 5mRNA表达量在伤后 8h显著升高 ,伤后 2 4h降低 ,但仍高于正常水平 ,而伤后 72h降至正常水平以下 ;组间比较显示 ,延迟组伤后 8h值显著高于早期复苏组 ,而 72h显著低于早期复苏组 ;两组回肠帕内特细胞与对照组比较无明显形态学改变。伤后 2 4h细菌移位频率早期复苏组和延迟复苏组显著高于对照组 ,延迟复苏组显著高于早期复苏组。结论 延迟复苏后的肠黏膜损伤并不涉及帕内特细胞 ;伤后 2 4h内发生的细菌移位与RD 5mRNA表达改变关系不大 ,而 72h后RD 5mRNA降低可能对细菌移位产生影响。

Objective To investigate whether intestinal bacterial translocation in scalded rat with delayed fluid resuscitation (DFR) was partly due to the reduction of the expression of rat defensin (RD), which was the most important defensin in rat intestinal defensin family excreted by Paneth cells. Methods Fifty-six SPF rats were randomized to 3 groups: sham injury group (n=8); early resuscitation (ER) group (n=24), receiving fluid resuscitation immediately after scald (30% TBSA, third degree); delayed resuscitation group (n=24), receiving fluid resuscitation 6 hours after scald. The animals (n=6, at each time point) were sacrificed at 8, 24, 72 hours after injury. The expression of RD-5 in the terminal ileum was determined with PCR technic. Morphological changes in ileal Paneth cells were observed. Quantitative bacterial cultures of mesenteric lymph nodes (MLN), liver, spleen and lung were also done. Results In both ER group and DR group, ileal RD-5 mRNA expression level was significantly increased at 8 hours after injury, and it began to decrease at 24 hours until the end of the experiment, when the level was much lower than that of the sham group. When two experimental groups were compared, RD-5 mRNA expression level was significantly higher at 8 hours and significantly lower at 72 hours in DR group than in ER group. There were no obvious morphological changes in ileal Paneth cells in all 3 groups. Although high incidence of bacterial translocation was observed in both experimental groups, it was significantly higher in DR group than in ER group. Conclusions DFR did not cause Panth cell damage, and RD-5 changes did not contribute to bacterial translocation in 24 hours after DFR, as the increase in RD-5 mRNA might be an innate protective reaction. However, the decrease in RD-5 production at 72 hours may play a role in bacterial transloca- tion.