Effect of exercise on turnover and fate of 4-14C$-cholesterol administered intraperitoneally and orally to rats

The fate of [4-14C]-cholesterol administered intraperitoneally or orally was compared in exercised (treadmill running for 14 days) and sedentary rats. Plasma triglyceride, phospholipid and cholesterol decreased in exercised rats and this reduction lasted at least for 10 days after exercise was terminated. When rats received [4-14C]-cholesterol intraperitoneally or orally, the turnover rate of serum cholesterol was considerably higher in exercised rats at the time shortly after the administration of the label. The radioactivity remaining in the liver was consistently lower in exercised rats, whereas that in extrahepatic tissues was the same between two groups. Excretion into feces of the label as total steroids was moderately enhanced by exercise. This effect was almost entirely ascribed to the increase in output of the label shortly after the administration. These results suggest that the mechanism responsible for cholesterol lowering effect of exercise is mainly attributable to the increase in turnover of cholesterol in the hepato-plasmic system. The moderate increase in fecal output of endogenous steroids may be the reflection of the increased turnover. (author)