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National Institute of Environmental Health Sciences

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Your Environment. Your Health.

Publication Detail

Title: Glutathione depletion exacerbates methylenedianiline toxicity to biliary epithelial cells and hepatocytes in rats.

Authors: Kanz, Mary F; Dugas, Tammy R; Liu, Hanlin; Santa Cruz, Vicente

Published In Toxicol Sci, (2003 Aug)

Abstract: Methylenedianiline (DAPM) initially injures epithelial cells of major bile ducts, which is followed by cholestasis, cholangitis, and hepatocellular damage. This pattern of biliary injury resembles that produced by alpha-naphthylisothiocyanate (ANIT), a classic bile duct toxicant. Our goal was to determine whether prior depletion of hepatic total glutathione (GSx), a condition reported to protect against biliary tract injury by ANIT, would also protect against DAPM-induced bile duct injury. A new protocol for extensive, sustained depletion of GSx was established. We found that administration of 1-bromoheptane followed 1 h later by buthionine sulfoximine resulted in an approximately 96% depletion of hepatic GSx that persisted through 6 h without biochemical or morphological signs of hepatic injury. Treatment of rats with a minimally hepatotoxic dose of DAPM (without GSx depletion) produced at 6 h injury similar to previous studies: moderate oncosis of biliary epithelial cells (BEC), mild edema of portal triads, and increases in glutathione S-transferase (GST) activities without alterations in hepatic GSx/glutathione disulfide (GSSG), coenzyme A (CoASH)/coenzyme A-glutathione disulfide (CoASSG), or thiobarbituric acid-reactive substances (TBARS). In contrast, DAPM treatment of GSx-depleted rats produced severe oncosis of BEC, marked inflammatory and edematous alterations to portal tracts, and oncosis/apoptosis in scattered hepatocytes. The observed acceleration and enhancement of DAPM-induced liver injury by GSx depletion was associated with a concurrent sevenfold increase in hepatic CoASSG and a fourfold decrease in the ratio of CoASH to CoASSG, compounds presumably localized to mitochondria and a purported index of mitochondrial thiol/disulfide status. These results indicate that: (1) GSx depletion exacerbates BEC and hepatocellular injury induced by DAPM, and (2) the mechanism by which DAPM causes liver injury is likely different from that of the classic bile duct toxicant, ANIT.

PubMed ID: 12773769 Exiting the NIEHS site

MeSH Terms: Allergens/administration & dosage; Allergens/toxicity*; Aniline Compounds/administration & dosage; Aniline Compounds/toxicity*; Animals; Apoptosis/drug effects; Bile Ducts/drug effects*; Bile Ducts/enzymology; Bile Ducts/pathology; Buthionine Sulfoximine/pharmacology; Coenzyme A/metabolism; DNA Fragmentation/drug effects; DNA Fragmentation/physiology; Epithelial Cells/drug effects; Epithelial Cells/enzymology; Epithelial Cells/pathology; Glutathione/deficiency*; Glutathione/metabolism; Hepatocytes/drug effects*; Hepatocytes/enzymology; Hepatocytes/pathology; Hydrocarbons, Brominated/pharmacology; Male; Rats; Rats, Sprague-Dawley; Research Support, U.S. Gov't, P.H.S.; Thiobarbituric Acid Reactive Substances/metabolism

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