High-dose estrogen treatment affects the levels of a protein called scavenger receptor BI (SR-BI) in rats' adrenal glands and livers. The researchers found that estrogen does not directly change SR-BI levels in these tissues. In the liver, the decrease in SR-BI is linked to increased activity of another protein called low density lipoprotein receptor (LDLR) caused by estrogen. In the adrenal glands, a hormone called adrenocorticotropic hormone (ACTH) is needed for estrogen to increase SR-BI levels. This study shows how estrogen impacts SR-BI expression in different tissues through separate mechanisms.