Scientific Publications by FDA Staff

J Pharmacol Exp Ther 2013 Jan;344(1):286-94

Mouse Liver Protein Sulfhydryl Depletion after Acetaminophen Exposure.

Yang X, Greenhaw J, Shi Q, Roberts DW, Hinson JA, Muskhelishvili L, Davis K, Salminen W

Acetaminophen (APAP)-induced liver injury is the leading cause of acute liver failure in many countries. This study determined the extent of liver protein sulfhydryl depletion not only in whole liver homogenate but also the zonal pattern of sulfhydryl depletion within the liver lobule. A single oral gavage dose of 150 or 300 mg/kg APAP in B6C3F1 mice produced increased serum alanine aminotransferase (ALT) levels, liver necrosis, and glutathione depletion in a dose-dependent manner. Free protein sulfhydryls were measured in liver protein homogenates by labeling with maleimide linked to a near infrared fluorescent dye followed by SDS-PAGE. Global free protein sulfhydryl levels were decreased significantly (48.4%) starting at 1 h after the APAP dose and maintained at this reduced level through 24 h. In order to visualize the specific hepatocytes that had reduced free protein sulfhydryl levels, frozen liver sections were labeled with maleimide linked to horseradish peroxidase. The centrilobular areas exhibited dramatic decreases in free protein sulfhydryls while the periportal regions were essentially spared. These free protein sulfhydryl-depleted regions correlated with areas exhibiting histopathological injury and APAP binding to protein. The majority of free protein sulfhydryl depletion was due to reversible oxidation since the global- and lobule-specific effects were essentially reversed when the samples were reduced with tris(2-carboxyethy)phosphine prior to maleimide labeling. These temporal and zonal pattern changes in protein sulfhydryl oxidation shed new light on the importance that changes in protein redox status might play in the pathogenesis of APAP hepatotoxicity.