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目的探讨钙摄入量对大鼠肝脏胆固醇代谢关键酶3-羟基-3-甲基戊二酰辅酶A还原酶(HMG-CoA还原酶)、7α-羟化酶(CYP7A)的mRNA表达影响。方法雄性Wistar大鼠经14 d诱导高胆固醇血症模型后,分别喂饲不同钙含量的纯合成高脂饲料42 d。结果经14 d诱导高胆固醇模型后,高脂模型组大鼠血浆胆固醇(TC)水平为(2.57±0.57)mmol/L(n=21),是常脂常钙组(1.49±0.14)mmol/L(n=8)的1.72倍。又经42 d喂饲含有处理因素的饲料后,各组大鼠摄食量和体重无变化;高脂高钙组心脏指数和肾脏指数分别显著低于、高于其他各组(P<0.05);随着钙含量增加,实验处理组大鼠骨密度也逐渐增加;高脂常钙组TC浓度为(2.32±0.75)mmol/L,比初始时下降了6.07%;高脂中钙组抑制TC增高能力强于常脂常钙组;除高脂高钙组外,钙摄入可使大鼠肝脏HMG-CoA还原酶mRNA的表达量呈现下降趋势,CYP7A mRNA的表达量呈现增强趋势。结论适量钙摄入可通过影响HMD-CoA还原酶和CYP7A基因的表达来降低或改善血浆胆固醇水平。
Objective To investigate the effect of calcium intake on the mRNA expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) and 7α-hydroxylase (CYP7A), which are the key enzymes of hepatic cholesterol metabolism in rats. Methods Male Wistar rats were induced with hypercholesterolemia for 14 days and then fed with pure diet of high-fat diet with different calcium content for 42 days. Results After 14 days of hypercholesterolemia, the level of TC in hyperlipidemic model group was (2.57 ± 0.57) mmol / L (n = 21), and was 1.49 ± 0.14 mmol / 1.72 times of L (n = 8). After feeding for 42 days, the food intake and weight of rats in each group remained unchanged. The indexes of heart and kidney in HF group were significantly lower than those in other groups (P <0.05). With the increase of calcium content, the BMD of rats in experimental group also increased gradually. The concentration of TC in hyperlipemic normal calcium group was (2.32 ± 0.75) mmol / L, decreased by 6.07% In addition to high-fat and high-calcium group, the expression of HMG-CoA reductase mRNA in rat liver showed a decreasing trend and the expression level of CYP7A mRNA showed an increasing trend. Conclusions A moderate amount of calcium intake can reduce or improve plasma cholesterol levels by affecting the expression of HMD-CoA reductase and CYP7A genes.