Dietary regulation of 3-hydroxy-3-methylglutaryl-CoA reductase from rat intestine.

The effect of dietary cholesterol on rat intestinal 3-hydroxy-3-methylglutaryl-coenzyme A reductase (EC 1.1.1.34) varied depending upon whether animals received the dietary cholesterol with polyunsaturated or saturated fats. When cholesterol was fed with polyunsaturates, the enzyme activity in both the jejunum and ileum was significantly suppressed, whereas only the enzyme in the jejunum was significantly suppressed when cholesterol was given with saturated fats. It is concluded that dietary cholesterol has a negative feedback effect on intestinal cholesterol synthesis.