Shefer S, Hauser S, Lapar V, Mosbach E H
J Lipid Res. 1973 Jul;14(4):400-5.
The specific activity (concentration) of microsomal HMG CoA reductase of intestinal crypt cells was studied in rats fed sterols and bile acids, either singly or in combination. It was found that the basal activity of the reductase was not suppressed by the administration of relatively large amounts of bile acid (taurocholate or taurochenodeoxycholate). Bile acids reduced the specific activity of the reductase only in rats in which the activity of the enzyme had first been enhanced by biliary diversion or by sitosterol feeding. In addition, bile acid feeding abolished the diurnal elevation of reductase activity that normally occurs between midnight and 2 a.m. In no case did bile acids reduce enzyme activity below basal levels. A pronounced (60%) reduction of intestinal HMG CoA reductase activity was observed in rats fed cholesterol and bile acid in combination. This reduction in activity could not be ascribed to an increase in intestinal bile acid flux but was associated with an increase in sterol concentration within the intestinal crypt cells. These results indicate that dietary sterols and bile acids both play a role in the regulation of intestinal HMG CoA reductase.
对单独或联合喂食固醇和胆汁酸的大鼠肠道隐窝细胞微粒体HMG CoA还原酶的比活性（浓度）进行了研究。发现给予相对大量的胆汁酸（牛磺胆酸盐或牛磺鹅去氧胆酸盐）并不会抑制还原酶的基础活性。胆汁酸仅在通过胆汁引流或喂食谷甾醇使酶活性首先增强的大鼠中降低还原酶的比活性。此外，喂食胆汁酸消除了通常在午夜至凌晨2点之间出现的还原酶活性的昼夜升高。在任何情况下，胆汁酸都不会使酶活性降低到基础水平以下。在联合喂食胆固醇和胆汁酸的大鼠中，观察到肠道HMG CoA还原酶活性显著降低（60%）。这种活性降低不能归因于肠道胆汁酸通量的增加，而是与肠道隐窝细胞内固醇浓度的增加有关。这些结果表明，膳食固醇和胆汁酸在肠道HMG CoA还原酶的调节中均起作用。
