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Immunocytochemical localization of Δ 3 , Δ 2 ‐enoyl‐CoA isomerase in rat liver. The effects of di‐(2‐ethylhexyl)phthalate, a peroxisome proliferator
Author(s) -
Yokota Sadaki,
Hirose Akihiko,
Mizugaki Michinao
Publication year - 1989
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1111/j.1768-322x.1989.tb00850.x
Subject(s) - peroxisome , biology , phthalate , biochemistry , clofibrate , mitochondrion , staining , isomerase , microbiology and biotechnology , enzyme , chemistry , receptor , genetics , organic chemistry
Immunocytochemical localization of Δ 3 , Δ 2 ‐enoyl‐CoA isomerase (isomerase) was investigated in rat liver. Livers of di‐(2‐ethylhexyl)phthalate) (DEHP)‐treated or untreated rats were perfusion‐fixed and embedded in Epon or Lowicryl K4M. By light microscopy, reaction deposits for the enzyme were present in the cytoplasmic granules of hepatocytes and interlobular bile duct epithelium. Weak staining was noted in sinus‐lining cells. After administration of DEHP, the granular staining of the hepatocytes was markedly enhanced, whereas the staining reaction of the sinus‐lining cells decreased. The isomerase staining pattern was quite similar to that of long‐chain acyl‐CoA dehydrogenase (a mitochondrial marker), but different from that of catalase (a peroxisomal marker). Under electron microscopy, gold particles for isomerase were seen to be confined mainly to mitochondria of the hepatocytes, the bile duct epithelial cells and sinus‐lining cells. Peroxisomes were weakly labeled. After DEHP administration, the peroxisomes were markedly induced, but the mitochondria were not. Quantitative analysis showed that the induction of the peroxisomal isomerase was only 2‐fold whereas the mitochondrial isomerase was enhanced about 5‐fold, 40 times as high as the peroxisomal enzyme. The results show that the mitochondria are the main intracellular site for isomerase and the peroxisomes a minor site. The mitochondrial isomerase of the rat liver is markedly induced by peroxisome proliferators, DEHP and clofibrate.