Sex mediated lipid metabolism in human aortic smooth muscle cells

When human aortic smooth muscle cells in culture were treated with pharmacological doses of estrogen and testosterone for 48 hrs, the rate of cholesterol synthesis measured both by acetate incorporation and the 3, hydroxy 3-methylglutaryl Co enzyme A reductase (HMG-CoA) activity declined significantly as compared to control. However, the rate of cholesterol esterification increased by 132% and 45% in response to testosterone and estrogen respectively. Also, acetate incorporation into fatty acids and fatty acid synthetase enzyme activity increased by hormonal treatment but remained in the free form especially by estrogen. Testosterone treatment resulted in more esterification (p less than .025) of fatty acid than estrogen treatment. Incubation with hormones for 48 hrs resulted in enhanced uptake of 14C-labeled cholesterol along with increased accumulation of cellular cholesterol. Increased synthesis of phospholipid and triglyceride by estrogen may be responsible for excretion of cellular sterol and fat. These results indicate that sex-hormones have an important effect on the regulation of lipid metabolism in human aortic cells.