饲粮阴阳离子差水平对小鼠血钙浓度及胃肠道组织钙结合蛋白-D9k mRNA相对表达水平的影响

本试验在前期建立了动物胃肠道钙代谢相关基因表达水平检测体系与表达谱分析的基础上,旨在进一步确定饲粮阴阳离子差(DCAD)水平对动物血钙浓度和胃肠道组织钙结合蛋白-D9k(Ca BP-D9k)mRNA相对表达水平的影响,为揭示低DCAD水平防治动物低血钙症的作用机制提供依据。将120只昆明小鼠随机分为3组,每组40只,自配种前3 d起分别饲喂DCAD水平为+300(高DCAD水平组,HD组)、+150(对照组,CON组)、-50(低DCAD水平组,LD组)的饲粮。检测母鼠产前20 d(-20 d)、产前5 d(-5 d)、产后当天(0 d)、产后3 d(+3 d)血钙浓度和胃肠道组织Ca BP-D9k mRNA相对表达水平。结果表明,与HD组相比,LD组显著提高了围产期内0 d、+3 d小鼠血钙浓度(P0.05),显著上调了小肠肠段(十二指肠、空肠、回肠)与结肠Ca BP-D9k mRNA相对表达水平(P0.05),这一效应在-5 d、0 d表现最为显著(P0.05),并在+3 d提高了小鼠空肠与结肠的Ca BP-D9k mRNA相对表达水平(P0.05)。统计结果显示,十二指肠、空肠与结肠3个位点的Ca BP-D9k mRNA相对表达水平与DCAD水平、血钙浓度具有显著的关联性(P0.05)。由此可见,降低DCAD水平可上调动物小肠及结肠肠段Ca BP-D9k mRNA相对表达水平,同时伴随更高的血钙浓度。这可能是低DCAD水平有效维持动物围产期血钙稳恒,降低低血钙发生率的重要途径。

Effects of Dietary Cation-Anion Difference Level on Plasma Calcium Concentration and Gastrointestinal Tract Tissues Calcium Binding Proteins-D9k mRNA Relative Expression Level of Mice during the Transition Period

Based on the calcium related gene expression profile and its analysis,the study was conducted to investigate the effects of dietary cation-anion difference (DCAD) level on plasma calcium concentration and gastrointestinal tract tissues calcium binding proteins-D9k (CaBP-D9k) relative expression level of mice during the transition period,and to clarify the mechanism of low DCAD level prevent hypocalcaemia.One hundred and twenty KM mice were randomly allotted 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),respectively.Plasma calcium concentration and gastrointestinal tract tissues CaBP-D9k mRNA relative expression level were detected 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 compared with the HD group,the plasma calcium concentration of mice at 0 d and +3 d during the transition period in LD group was significantly increased (P＜0.05),and the CaBP-D9k mRNA relative expression level was significantly up-regulated in duodenum,jejunum,ileum and colon (P＜0.05),especially observed on-5 d before parturition and 0 d at parturition (P＜0.05).Also,CaBP-D9k mRNA relative expression level was significantly increased in jejunum and colon on the +3 d after parturition (P＜0.05).Moreover,there was a significant correlation between CaBP-D9k mRNA relative expression level in duodenum,jejunum and colon and plasma calcium concentration.In conclusion,low DCAD level is able to up-regulate CaBP-D9k mRNA relative expression level in small intestine and colon,accompany with greater plasma calcium concentration.This is possibly an important way of low DCAD level maintains plasma calcium homeostasis during the transition period,and reduce the occurrence rate of hypocalcemia.