Effect of Cholesterol Feeding and Fasting on Sterol Synthesis in Seventeen Tissues of the Rat

Rates of sterol synthesis were measured in 17 tissues of the rat, and the responsiveness of these rates to cholesterol feeding and to fasting was determined. The liver and gastrointestinal tract together account for 90% of synthetic activity of the whole body. After the rats had been fed cholesterol or fasted, liver synthesis was markedly decreased, whereas synthetic rates in all other organs tested were essentially unaffected (this conclusion applies to synthesis of cholesterol and of five other digitonin-precipitable tissue sterols). Consequently, the highest rate of cholesterogenesis in the cholesterol-fed or fasted rat is found in the gastrointestinal tract.