中文摘要：

本试验旨在通过研究饲粮阴阳离子差（DCAD）水平对围产期小鼠血钙浓度和胃肠道组织维生素D受体（VDR）mRNA表达水平的影响,揭示低DCAD水平防治低血钙症的作用机理。将120只围产期小鼠分为3组,每组40只,分别饲喂DCAD水平为＋300（高DCAD水平组,HD组）、＋150（对照组,CON组）、-150 mmol/kg DM（低DCAD水平组,LD组）的饲粮。在小鼠产前20 d（-20 d）、产前5 d（-5 d）、产仔当天（0 d）、产后3 d（3 d）,每组随机选取10只采血并采集胃、十二指肠、空肠、回肠、盲肠、结肠样品,测定血钙浓度与组织VDR mRNA表达水平。结果表明：在整个试验期和单个采血时间点,LD组较CON组、HD组显著提高小鼠血钙浓度（P〈0.05）。与CON组、HD组相比,在-20 d,低DCAD水平显著提高了空肠、回肠和结肠的VDR mRNA表达水平（P〈0.05）;在-5 d,低DCAD水平显著提高了空肠、结肠VDR mRNA表达水平;在0 d,低DCAD水平显著提高了十二指肠VDR mRNA表达水平（P〈0.05）;在＋3 d,低DCAD水平显著提高了十二指肠、空肠和结肠VDR mRNA表达水平（P〈0.05）。由此可见,低DCAD水平可提高围产期小鼠胃肠道组织VDR mRNA表达水平,增加血钙浓度。这可能是低DCAD水平有效防治低血钙症的作用机理。

英文摘要：

This experiment was conducted to study the effects of dietary cation-anion difference （ DCAD） level on plasma calcium concentration and gastrointestinal tract vitamin D receptor （ VDR ） mRNA expression level of mice during the transition period, and to exposit the mechanism of low DCAD level control of hypocalce-mia. One hundred and twenty mice during the transition period were randomly allocated into 3 groups with 40 mice in each group, mice in the 3 groups were fed 3 diets with DCAD level at＋300 （ high DCAD level group, HD group） , ＋150 （ control group, CON group） , and -150 （ low DCAD level group, LD group） , respec-tively. Ten mice for each group were sacrificed to collect blood sample for plasma calcium concentration analy-sis and gastrointestinal tract tissues （ stomach, duodenum, jejunum, ileum, cecum, and colon） samples for VDR mRNA expression level detection at 4 time points：day of 20 （-20 d） and 5 （-5 d） before kidding, day of kidding （ 0 d） , and day of 3 after kidding （＋3 d） . The results showed that the plasma calcium concentra-tion in LD group was higher than that in HD and CON groups for the whole and individual blood sampling time （ P〈0.05） . At-20 d, compared with HD and CON groups, the VDR mRNA expression level in jejunum, ile-um and colon in LD group was significantly increased （ P〈0.05）; at -5 d, the VDR mRNA expression level in jejunum and colon in LD group was significantly increased （ P〈0.05）; at 0 d, the VDR mRNA expression level in duodenum in LD group was significantly increased （ P〈0.05）; at ＋3 d, the VDR mRNA expression level in duodenum, jejunum and colon in LD group was significantly increased （ P〈0.05） . The results indica-ted that low DCAD level can increase VDR mRNA expression level in gastrointestinal tract of mice during the transition period, and increase plasma calcium concentration, which was probably the mechanism of low DCAD preventing hypocalcemia.