Inhibitory effect of prostaglandin E2 on cholesterol ester accumulation in macrophages.

The effects of prostaglandin E2 (PGE2) on the metabolism of beta-migrating very low density lipoprotein (beta-VLDL) in rat peritoneal macrophages were investigated. When cultured in vitro, macrophages apparently incorporated labelled beta-VLDL time-dependently until 12 h, when the incorporation appeared to reach a plateau. Labelled cholesterol ester in the macrophages increased rapidly until 2 h of incubation, did not change from 2 to 6 h, and then increased markedly until 28 h. Labelled free cholesterol in the macrophages increased until 12 h and then decreased until 28 h. Exogenously added PGE2 (10(-7) approximately 10(-5) M) inhibited the accumulation of labelled cholesterol ester between 6h and 28h with or without increasing the level of labelled free cholesterol. These results suggest that PGE2 prevented cholesterol ester accumulation by stimulating either hydrolysis of cholesterol ester or excretion of free cholesterol.