Cell cholesterol esters and high-density lipoprotein plasma levels during liver hyperplasia in choline-fed male and female rats

Sexual dimorphism exists in the response of rats to lead nitrate, liver hyp erplasia occuring earlier and being more pronounced in males. Excess dietar y choline in females shifted the growth pattern towards that of males. To d etermine whether phosphatidylcholine-induced growth modulations could be re lated to a derangement of cholesterol metabolism, liver accumulation of cho lesterol esters and plasma lipoprotein patterns were investigated. In males , lead-induced liver hyperplasia was associated with increased total choles terol hepatic content, accumulated cholesterol esters and reduced concentra tion of plasma High Density Lipoprotein (HDL) cholesterol. Females were les s responsive to the liver mitogenic signal of lead nitrate; there was no el evation of cholesterol content nor any marked accumulation of cholesterol e sters. This is consistent with the lack of change in the plasma levels of H DL cholesterol. Continuous choline feeding displaced the liver cholesterol ester pattern and plasma HDL cholesterol levels in females, and in parallel that of DNA synthesis, towards those of males. Choline was not observed to have any effect in males. These results suggest that the derangement of ph osphatidylcholine metabolism induces growth-related changes in cholesterol turnover; they are consistent with the proposal that the intracellular cont ent of cholesterol esters may have a role in regulating liver growth rates.