IMMUNOHISTOCHEMICAL LOCALIZATION OF PEROXISOMAL ENZYMES IN DEVELOPINGRAT-KIDNEY TISSUES

We studied the developmental changes in the localization of peroxisome -specific enzymes in rat kidney tissues from embryonic Day 16 to postn atal Week 10 by immunoblot analysis and immunohistochemistry, using an tibodies for the peroxisomal enzymes catalase, D-amino acid oxidase, L -alpha-hydroxyacid oxidase (isozyme B), and enoyl-CoA hydratase/3-hydr oxyacyl-CoA dehydrogenase bifunctional protein. Peroxisomal enzymes we re detected in the neonatal kidney by immunoblot analysis and their am ount increased with kidney development. By light microscopic immunohis tochemistry, they were first localized in a few proximal tubules in th e juxtamedullary cortex of 18-day embryos. The distribution of proxima l tubules positive for them expanded towards the superficial cortex wi th development. The full thickness of the cortex became positive for t he staining by 14 days after birth. Peroxisomes could be detected by e lectron microscopy in structurally immature proximal tubules in 18-day embryos. Their size increased and the ultrastructure of subcompartmen ts became clear with continuing development of proximal tubules. These results show that peroxisomal enzymes appear in the immature proximal tubules in the kidney of embryos and that the ultrastructure of the p eroxisomes and localization of the peroxisomal enzymes develop along w ith the maturation of proximal tubules and kidney tissues.