The effect of ethanol, ethanol metabolizing enzyme inhibitors, and Vitamin E on regulating glutathione, glutathione S-transferase, and S-adenosylmethionine in mouse primary hepatocyte

Maxwell Afari Gyamfi, Yu-Jui Yvonne Wan

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21 Citations (Scopus)

Abstract

We studied changes in the antioxidant systems involved in hepatoprotection after ethanol exposure in primary culture of mouse hepatocytes. Ethanol decreased glutathione (GSH) levels and the S-adenosylmethionine (SAMe) to S-adenosylhomocysteine (SAH) ratio by 53% and 22%, respectively. Cytosolic glutathione S-transferase (GST) activity was significantly lower in ethanol exposed hepatocytes, which was accompanied by an increase in GST activity in the culture medium. When specific substrates for mu- and pi-class GST were utilized, ethanol significantly decreased the mu- and pi-class GST activity by 53% and 13%, respectively. Lipid peroxidation (LPO), assessed by the thiobarbituric acid assay, increased to 221% of control by ethanol and was potentiated by cyanamide, an aldehyde dehydrogenase inhibitor. The changes in LPO, cytosolic GST activity, GSH levels and SAMe/SAH ratio in ethanol exposed hepatocytes were completely or partially reversed by either Vitamin E or 4-methylpyrazole, an alcohol dehydrogenase (ADH) inhibitor. Retinoid X receptor α-deficient (RXRα KO) mice, which are more susceptible to ethanol-induced liver toxicity, have decreased pi-class GST (56%), mu-class GST (28%), and glutathione peroxidase (35%) activities compared with wild type. Taken together, primary hepatocyte provides a valuable model to analyze ethanol-induced oxidative stress. The inhibition of mu-class GST activity by ethanol and the decreased pi-class GST activity in RXRα KO mice implicate the importance of these isozymes in ethanol detoxification process.

Original languageEnglish (US)
Pages (from-to)53-61
Number of pages9
JournalHepatology Research
Volume35
Issue number1
DOIs
StatePublished - May 2006
Externally publishedYes

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S-Adenosylmethionine
Enzyme Inhibitors
Glutathione Transferase
Vitamin E
Glutathione
Hepatocytes
Ethanol
Glutathione S-Transferase pi
S-Adenosylhomocysteine
Lipid Peroxidation
Cyanamide
Retinoid X Receptors
Aldehyde Dehydrogenase
Alcohol Dehydrogenase
Glutathione Peroxidase
Isoenzymes
Culture Media
Oxidative Stress
Antioxidants

Keywords

  • Alcoholic liver disease
  • Ethanol
  • Glutathione S-transferase
  • Retinoid X receptor alpha
  • S-Adenosylmethionine
  • Vitamin E

ASJC Scopus subject areas

  • Gastroenterology

Cite this

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title = "The effect of ethanol, ethanol metabolizing enzyme inhibitors, and Vitamin E on regulating glutathione, glutathione S-transferase, and S-adenosylmethionine in mouse primary hepatocyte",
abstract = "We studied changes in the antioxidant systems involved in hepatoprotection after ethanol exposure in primary culture of mouse hepatocytes. Ethanol decreased glutathione (GSH) levels and the S-adenosylmethionine (SAMe) to S-adenosylhomocysteine (SAH) ratio by 53{\%} and 22{\%}, respectively. Cytosolic glutathione S-transferase (GST) activity was significantly lower in ethanol exposed hepatocytes, which was accompanied by an increase in GST activity in the culture medium. When specific substrates for mu- and pi-class GST were utilized, ethanol significantly decreased the mu- and pi-class GST activity by 53{\%} and 13{\%}, respectively. Lipid peroxidation (LPO), assessed by the thiobarbituric acid assay, increased to 221{\%} of control by ethanol and was potentiated by cyanamide, an aldehyde dehydrogenase inhibitor. The changes in LPO, cytosolic GST activity, GSH levels and SAMe/SAH ratio in ethanol exposed hepatocytes were completely or partially reversed by either Vitamin E or 4-methylpyrazole, an alcohol dehydrogenase (ADH) inhibitor. Retinoid X receptor α-deficient (RXRα KO) mice, which are more susceptible to ethanol-induced liver toxicity, have decreased pi-class GST (56{\%}), mu-class GST (28{\%}), and glutathione peroxidase (35{\%}) activities compared with wild type. Taken together, primary hepatocyte provides a valuable model to analyze ethanol-induced oxidative stress. The inhibition of mu-class GST activity by ethanol and the decreased pi-class GST activity in RXRα KO mice implicate the importance of these isozymes in ethanol detoxification process.",
keywords = "Alcoholic liver disease, Ethanol, Glutathione S-transferase, Retinoid X receptor alpha, S-Adenosylmethionine, Vitamin E",
author = "Gyamfi, {Maxwell Afari} and Wan, {Yu-Jui Yvonne}",
year = "2006",
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N2 - We studied changes in the antioxidant systems involved in hepatoprotection after ethanol exposure in primary culture of mouse hepatocytes. Ethanol decreased glutathione (GSH) levels and the S-adenosylmethionine (SAMe) to S-adenosylhomocysteine (SAH) ratio by 53% and 22%, respectively. Cytosolic glutathione S-transferase (GST) activity was significantly lower in ethanol exposed hepatocytes, which was accompanied by an increase in GST activity in the culture medium. When specific substrates for mu- and pi-class GST were utilized, ethanol significantly decreased the mu- and pi-class GST activity by 53% and 13%, respectively. Lipid peroxidation (LPO), assessed by the thiobarbituric acid assay, increased to 221% of control by ethanol and was potentiated by cyanamide, an aldehyde dehydrogenase inhibitor. The changes in LPO, cytosolic GST activity, GSH levels and SAMe/SAH ratio in ethanol exposed hepatocytes were completely or partially reversed by either Vitamin E or 4-methylpyrazole, an alcohol dehydrogenase (ADH) inhibitor. Retinoid X receptor α-deficient (RXRα KO) mice, which are more susceptible to ethanol-induced liver toxicity, have decreased pi-class GST (56%), mu-class GST (28%), and glutathione peroxidase (35%) activities compared with wild type. Taken together, primary hepatocyte provides a valuable model to analyze ethanol-induced oxidative stress. The inhibition of mu-class GST activity by ethanol and the decreased pi-class GST activity in RXRα KO mice implicate the importance of these isozymes in ethanol detoxification process.

AB - We studied changes in the antioxidant systems involved in hepatoprotection after ethanol exposure in primary culture of mouse hepatocytes. Ethanol decreased glutathione (GSH) levels and the S-adenosylmethionine (SAMe) to S-adenosylhomocysteine (SAH) ratio by 53% and 22%, respectively. Cytosolic glutathione S-transferase (GST) activity was significantly lower in ethanol exposed hepatocytes, which was accompanied by an increase in GST activity in the culture medium. When specific substrates for mu- and pi-class GST were utilized, ethanol significantly decreased the mu- and pi-class GST activity by 53% and 13%, respectively. Lipid peroxidation (LPO), assessed by the thiobarbituric acid assay, increased to 221% of control by ethanol and was potentiated by cyanamide, an aldehyde dehydrogenase inhibitor. The changes in LPO, cytosolic GST activity, GSH levels and SAMe/SAH ratio in ethanol exposed hepatocytes were completely or partially reversed by either Vitamin E or 4-methylpyrazole, an alcohol dehydrogenase (ADH) inhibitor. Retinoid X receptor α-deficient (RXRα KO) mice, which are more susceptible to ethanol-induced liver toxicity, have decreased pi-class GST (56%), mu-class GST (28%), and glutathione peroxidase (35%) activities compared with wild type. Taken together, primary hepatocyte provides a valuable model to analyze ethanol-induced oxidative stress. The inhibition of mu-class GST activity by ethanol and the decreased pi-class GST activity in RXRα KO mice implicate the importance of these isozymes in ethanol detoxification process.

KW - Alcoholic liver disease

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