Gastroenterology

Gastroenterology

Volume 114, Issue 1, January 1998, Pages 164-174
Gastroenterology

Liver, Pancreas, and Biliary Tract
Vitamin E reduces oxidant injury to mitochondria and the hepatotoxicity of taurochenodeoxycholic acid in the rat,☆☆

Presented in part at the American Gastroenterological Association Annual Meeting, May 1994, and at the American Association for the Study of Liver Disease Annual Meeting, November 1994, and published in abstract form (Gastroenterology 1994;106:A1029 and Hepatology 1994;20:178A).
https://doi.org/10.1016/S0016-5085(98)70644-4Get rights and content

Abstract

Background & Aims: Hydrophobic bile acids have been implicated in the pathogenesis of cholestatic liver injury. The hypothesis that hydrophobic bile acid toxicity is mediated by oxidant stress in an in vivo rat model was tested in this study. Methods: A dose-response study of bolus intravenous (IV) taurochenodeoxycholic acid (TCDC) in rats was conducted. Rats were then pretreated with parenteral α-tocopherol, and its effect on IV TCDC toxicity was evaluated by liver blood tests and by assessing mitochondrial lipid peroxidation. Results: Four hours after an IV bolus of TCDC (10 μmol/100 g weight), serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels peaked, hepatic mitochondria showed evidence of increased lipid peroxidation, and serum bile acid analysis was consistent with a cholestatic injury. Liver histology at 4 hours showed hepatocellular necrosis and swelling and mild portal tract inflammation. Treatment with parenteral α-tocopherol was associated with a 60%-70% reduction in AST and ALT levels, improved histology, and a 60% reduction in mitochondrial lipid peroxidation in rats receiving TCDC. Conclusions: These data show that hepatocyte injury and oxidant damage to mitochondria caused by IV TCDC can be significantly reduced by pretreatment with the antioxidant vitamin E. These in vivo findings support the role for oxidant stress in the pathogenesis of bile acid hepatic toxicity.

GASTROENTEROLOGY 1998;114:164-174

Section snippets

Materials

All chemicals were obtained in analytical purity from the suppliers. Bovine serum albumin (fraction V) was obtained from Calbiochem (La Jolla, CA), bile acids from Sigma Chemical Co. (St. Louis, MO), digitonin from Sigma, and parenteral vitamin E (all-rac-α-tocopherol, Ephynal) from Hoffmann–LaRoche (Nutley, NJ).

Development of experimental model of IV TCDC toxicity

The first phase of this study was the development of an IV model of TCDC toxicity in the rat that produced a significant but reversible hepatic injury. For all experiments, young adult

In vivo TCDC toxicity model and mitochondrial lipid peroxidation

IV bolus injections of TCDC in rats caused a significant increase in serum AST and ALT concentrations in a dose-dependent manner (Table 1), with peak values attained 4 hours after injection.

. Dose-response of IV TCDC and hepatic toxicity

Empty CellDose of IV TCDC (μmol/100 g body wt)
Time after IV TCDC dose0 (n = 4)5 (n = 4)10 (n = 5)20 (n = 4)
0 h
 AST62 ± 173 ± 992 ± 870 ± 6
 ALT54 ± 552 ± 653 ± 364 ± 9
4 h
 AST66 ± 6121 ± 243679 ± 11051456 ± 748
 ALT51 ± 892 ± 231855 ± 7011712 ± 554
8 h
 AST59 ± 14110 ± 122233 ± 1906

Discussion

Recent investigations into the pathogenesis of cholestatic liver injury have focused on the role of hydrophobic bile acids.22, 23, 24, 25, 26, 27 In this study, we developed a novel in vivo model of bile acid toxicity that uses a single-bolus IV injection of TCDC, a conjugate of the bile acid most implicated in cholestatic liver injury.5, 6, 7 An IV dose of 10 μmol/100 g body wt in young adult male rats produced a significant but reversible injury to hepatocytes, which was maximum at 4 hours

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    Address requests for reprints to: Ronald J. Sokol, M.D., Department of Pediatrics, The Children's Hospital, Box B290, 1056 East 19th Avenue, Denver, Colorado 80218. Fax: (303) 764-8025.

    ☆☆

    Supported in part by grants RO1DK38446 and IP30DK34914 from the National Institutes of Health and the Abbey Bennett Liver Research Fund.

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