Estrogen hormones reduce lipid peroxidation in cells and tissues of the central nervous system

Effects of estrogen hormones on lipid peroxidation (LPO) were examined in r at brain homogenates (RBHs), hippocampal HT 22 cells, rat primary neocortic al cultures, and human brain homogenates (HBHs). Dose-response curves indic ated half-maximal effective concentrations (EC50) of 5.5 and 5.6 mM for iro n-induced LPO in RBHs and HT 22 homogenates. Incubation of living rat prima ry neocortical cultures with iron resulted in an EC50 of 0.5 mM, whereas cu lture homogenates showed an EC50 of 1.2 mM. Estrogen hormones reduced LPO i n all systems: In RBHs, estrone inhibited iron-induced LPO to 74.1 +/- 5.8% of control levels (17 beta-estradiol: 71.3 +/- 0.1%) at a concentration of 10 mu M. In hippocampal HT 22 cell homogenates, levels of LPO were reduced to 74.8 +/- 5.5% by estrone and to 47.8 +/- 6.2% by 17 beta-estradiol. In living neocortical cultures, 17 beta-estradiol decreased iron-induced LPO t o 79.2 +/- 4.8% and increased the survival of cultured neuronal cells. Of t he other steroid compounds tested (corticosterone, progesterone, testostero ne), only progesterone decreased LPO in HT 22 cell homogenates. In HBHs, LP O was dose-dependently increased by iron concentrations from 2.7 to 6.0 mM. Incubation with estrogens resulted in a dose-dependent inhibition of LPO t o 53.8 +/- 8.6% with 10 mu M 17 beta-estradiol, whereas estrone failed to a ffect iron-induced LPO to a significant extent. Nonestrogenic steroids, inc luding hydrocortisol, did not show significant effects on LPO in HBHs.