[33] Ultrastructural localization of light-induced lipid peroxides

For analysis of transport and processing of lipid peroxides, it is necessary to be able to localize lipid peroxides at the ultrastructural level. A method that uses benzidine-reactive substances and that is able to detect lipid peroxides at the ultrastructural level in rat and mouse tissues is discussed. The method presented in the chapter offers a simple application for the ultrastructural localization of lipid peroxides that can be used to investigate the formation, decomposition, or transport of lipid peroxides. A method for the ultrastructural localization of lipid peroxides in the retina of rats and mice was developed. The availability of a method for the localization of lipid peroxides at ultrastructural levels, coupled with the effect on the retina of modifications in light exposure, offers the possibility of investigating the formation, transport, and processing of benzidine-reactive substances (BRS) during the digestion of peroxidative-damaged shed tips of rod outer segment (ROS) in the retinal pigment epithelium (RPE). The chapter discusses peroxidation of rat retinas by light exposure using three-month-old long Evans rats, which are kept in single cages under a 12-hr light/dark regimen. The procedures described here are a modification of methods developed for the localization of peroxides in pig and hamster retinas.