Protective effect of catecholestrogen on lipid hydroperoxide-induced injury to cultured bovine aortic endothelial cells and on lipid peroxidation of low-density lipoprotein

When bovine aortic endothelial cells were incubated in Dulbecco's modified Eagle's medium containing 5% fetal bovine serum and 5 nmol/ml (in terms of malondialdehyde) of linoleic acid hydroperoxide, release of lactate dehydrogenase (LDH) from the cells into the medium increased over a 2-4 h incubation period, reaching a maximum level of about 80% of the total activity of LDH. In the presence of 17 beta-estradiol (E(2)) or 2-hydroxyestradiol (2-OHE(2)), the LDH release was inhibited depending on their concentration. The IC50 values of the inhibition were approximately 5 and 1 mu M, respectively. The lipid peroxide level in the cultured endothelial cells increased upon incubation with the hydroperoxide, which increase was suppressed markedly by 2-OHE(2) and slightly by E(2). Lipid peroxidation of low-density lipoprotein was inhibited markedly by 2-OHE(2) and slightly by E(2).