缺锌对生长期大鼠小肠黏膜维生素D受体及钙结合蛋白表达水平的影响

Effect of zinc deficiency on the protein expression of vitamin D receptor and calcium binding protein in growth-stage rats duodenal mucosa

目的研究锌缺乏对生长期大鼠小肠黏膜维生素D受体(VDR)和钙结合蛋白(CaBP)表达水平的影响,探讨锌缺乏影响钙吸收的基因转录调节作用的机制。方法刚断奶的雄性大鼠随机分为缺锌组(ZD)、配饲组(PF)、对照组(ZA),每组10只。ZA组自由食用含锌29.5μg/g的正常饲料;ZD组自由食用含锌0.4μg/g的缺锌饲料;PF组食用含锌29.5μg/g的正常饲料,但进食量限制为缺锌组大鼠前一日的进食量。喂养15 d后处死,取小肠黏膜,用免疫组化及W estern-b lot方法检测小肠黏膜VDR及CaBP的表达。结果免疫组化表明ZD组大鼠小肠黏膜表达蛋白明显减少,经图像分析,在1个视野内,VDR、CaBP蛋白表达数低于PF组与ZA组,ZD组、PF组、ZA组VDR蛋白表达数分别为52、162、220;CaBP蛋白表达数分别为169、240、280,差异均有统计学意义(P<0.001)。W estern-b lot也显示ZD组VDR与CaBP蛋白表达量明显少于PF组与ZA组,差异有统计学意义(P<0.001)。结论锌缺乏通过改变VDR蛋白的表达,从而影响靶基因CaBP的表达,进而影响钙吸收,导致骨生成障碍。

Objective To study the effect of zinc deficiency on the protein expression of vitamin D receptor （VDR） and calcium binding protein（CaBP） in growth-term rats duodenal mucosa and to clarify the mechanism of zinc deficiency affecting the calcium absorption by gene transcription. Methods Thirty weaning male rats were randomly divided into three groups ： zinc deficiency （ ZD）, paired-fed （PF） and zinc adequation （ZA）. The ZA group received a diet containing 29. 5 μg/g diet ad libitum; the ZD group received a diet containing less than 0.4 μg zinc/g diet ad libitum. To eliminate the effect of zinc deficiency on appetite, the PF group received a zinc-adequate diet restricted to the quantity of food consumed the previous day by the ZD rats. After 15 days feeding, duodenal mucosa was taken to measure expression of the protein of VDR and of CaBP by immunohistochemistry and Western-blotting. Results Immunohistochemistry demonstrated that the intestinal mucosal expression of both VDR protein and CaBP protein in ZD rats significantly decreased. Analysis of the photographs showed that the number of cells expressed VDR protein in ZD rats was significantly less than that of the PF and ZA rats （ P 〈 0. 001 ）. The number of cells which expressed VDR protein in ZD, PF, and ZA groups was 52, 162, and 220, and the number of cells which expressed CaBP protein was 169, 240 and 280 （ F = 132 and 22, P 〈 0. 001 ）. Western-blotting showed similar results. Conclusions Zinc deficiency, by changing the activity of VDR, changes the protein expression of VDR, and thus affects the transcription of the target gene CaBP, resulting in the absorption of calcium that causes allo-osteogenesis.