DIFFERENCES IN 27-HYDROXYCHOLESTEROL CONCENTRATIONS IN PLASMA AND LIVER OF BABOONS WITH HIGH AND LOW RESPONSES TO DIETARY-CHOLESTEROL AND FAT

Selective breeding has produced baboon progeny that have low or high r esponse in plasma low-density lipoprotein (LDL) cholesterol when fed a high cholesterol and high fat (HCHF) diet. We examined differences in bile acid metabolism between low and high responding baboons by measu ring the most abundant oxysterol in plasma and liver. Low responding b aboons had higher concentrations of plasma and liver 27-hydroxycholest erol than high responding baboons on the HCHF diet but not on the chow diet. The increased hepatic 27-hydroxycholesterol in low responders w as associated with an increase in sterol 27-hydroxylase activity as co mpared to high responders. These studies suggest that the hepatic ster ol 27-hydroxylase is induced by dietary cholesterol and this induction is much higher in low responding baboons.