IMMUNOHISTOCHEMICAL LOCALIZATION OF LIPOPEROXIDATION PRODUCTS IN NORMAL HUMAN PLACENTA

4-Hydroxynonenal (4-HNE) is a major propagation product of lipid perox idation that is supposed to be responsible for some of the effects ass ociated with oxidative stress in tissues. We have investigated the pos sible occurrence and distribution of 4-HNE-immunoreactivity in human n ormal placenta using immunocytochemistry. Specific immunostaining was observed in cytotrophoblast cells, syncytiotrophoblast, some cells of the villous mesenchyme and some endothelial cells of first trimester a nd term placentae. The detection of 4-HNE-immunoreactivity in placenta raises the question whether lipoperoxidation products are produced lo cally in placental cells or represent exogenous products that derive f rom maternal blood flow. Since trophoblastic cells and villous macroph ages are provided by a scavenger receptor, it is conceivable that thes e cells mag play a protective role with regard to the diffusion of lip operoxidation products from the mother to the embryo. However, since a significant degree of lipid oxidative modification does not take plac e in plasma, it is presumed that 4-HNE is a local product of placental metabolism. In line with this hypothesis, it is proposed that materna l low density lipoproteins, which are the major source of cholesterol for placental steroid synthesis, might be oxidized by villous cells du ring their traversal through the villous wall. (C) 1997 W. B. Saunders Company Ltd.