大鼠肠黏膜上皮occludin蛋白在发育过程中的变化

Variation of occludin during development process in intestinal mucosa of rats

目的研究在不同发育阶段大鼠的肠黏膜上皮中紧密连接蛋白occludin的变化情况,探索其与肠黏膜屏障相关疾病的潜在关系。方法于SD大鼠孕18d(E18)、生后1d(P1)、生后7d(P7)、生后21d(P21)、生后28d(P28)时取出末端回肠,HE染色观察其绒毛长度;免疫印迹(Western blot)检测occludin蛋白的表达水平;免疫荧光(Immunofluorescence)观察occludin蛋白的分布以及荧光强度。结果HE染色结果显示肠绒毛长度随着发育而增长,生后21d以后则趋于稳定;免疫印迹结果显示occludin蛋白的表达水平在出生后有一过性下降,从E18的0.34±0.02降至P1的0.16±0.02,而后随年龄增长,并在P7(0.52±0.06)时超过E18水平(P<0.05);免疫荧光结果显示occludin蛋白在回肠末端主要分布于黏膜层,与E18组相比,其荧光强度在出生后(P1组)有一过性下降,之后随年龄而逐渐增加。结论大鼠末端回肠黏膜绒毛的形态和紧密连接蛋白occludin随年龄增长而逐渐发育,但在出生后短期出现一过性下降过程,可能与此期易发坏死性小肠结肠炎有关。

Objective To explore the variation of tight junctions during different developmental stages in rats and examine the potential association between TJs and intestinal mucosal disease. Methods Distal ileum was dissected from rats at embryonic day (E18), postnatal day (P1), P7, P21 and P28. HE staining was used for observing the villus length. Western blot was employed for measuring the protein level of occludin. Immunofluorescence was utilized for observing the distribution of occludin and quantifying the alterations of occludin. Results The length of intestinal villus increased with age and then stabilized after post-natal day 21. Western bolt showed a transient postnatal decrease of occludin expression from E18 (0.34±0.02) to P1 (0.16±0.02) (P<0.05). Then it increased with age. Immunofluorescent signals of occludin spread over mucosal layer and intensity of signals experienced a transient postnatal decrease and then increased with age. Conclusions The morphology of distal ileum is maturing with advancing age. However, there is a transient postnatal decrease of occludin expression and then occludin expression increases with age. It is probably associated with necrotizing enterocolitis.