The effects of treadmill exercise on hepatic cholesterogenesis and fecal steroid excretion were studied using male Wistar rats fed a commercial pellet ration. Exercise, in comparison with ad libitum or pair-feeding sedentary groups, caused the following significant changes: (i) a reduction in the concentration of plasma triglyceride, phospholipid and cholesterol; (ii) a reduction in liver weight; (iii) increases in hepatic 3-hydroxy-3-methylglutaryl-CoA reductase activity and incorporation of mevalonate into digitonin precipitable sterol; (iv) increases in excretion of neutral and acidic steroids into the feces; (v) the increase in lipoprotein lipase activity in the cardiac muscle, and (vi) the decrease in the concentration of carcass triglyceride but not of cholesterol. These data suggest that the mechanism responsible for the plasma cholesterol-lowering effect of exercise is attributable to an increase in excretion of fecal neutral and acidic steroids accompanied by an acceleration of cholesterol turnover in the body.

Rats were fed plant sterols containing campesterol and beta-sitosterol in the differerent proportions, and their distribution in serum lipoproteins and in liver subcellular fractions was determined. In serum lipoproteins, the percentage as well as the concentration of plant sterols increased with the increase in the density of lipoproteins. Thus, high density lipoprotein (HDL) contained the highest and very low density lipoprotein (VLDL), the lowest. Also, there were distinct differences in the ratio of campesterol to sitosterol among lipoproteins, it was the highest in VLDL and lowest in HDL. Quantitatively, more than 75% of campesterol and 80% of sitosterol were carried in HDL; the values were significantly different from those of cholesterol (ca. 70%) in relation to total cholesterol. The distribution of plant sterols in liver subcellular fractions was virtually the same with that of cholesterol. Both nuclei and microsomes contained approximately 40% of total plant sterols.

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