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 response 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 measuring the most abundant oxysterol in plasma and liver. Low responding baboons had higher concentrations of plasma and liver 27-hydroxycholesterol than high responding baboons on the HCHF diet but not on the chow diet. The increased hepatic 27-hydroxycholesterol in low responders was associated with an increase in sterol 27-hydroxylase activity as compared to high responders. These studies suggest that the hepatic sterol 27-hydroxylase is induced by dietary cholesterol and this induction is much higher in low responding baboons.