Epigallocatechin gallate (EGCG) is a green tea antioxidant with adverse effects on rat liver mitochondria and hepatocytes at high doses. Here, we assessed whether low doses of EGCG would protect these systems from damage induced by tert-butyl hydroperoxide (tBHP). Rat liver mitochondria or permeabilized rat hepatocytes were pretreated with EGCG and then exposed to tBHP. Oxygen consumption, mitochondrial membrane potential (MMP), and mitochondrial retention capacity for calcium were measured. First, 50 μM EGCG or 0.25 mM tBHP alone increased State 4 Complex I-driven respiration, thus demonstrating uncoupling effects; tBHP also inhibited State 3 ADP-stimulated respiration. Then, the coexposure to 0.25 mM tBHP and 50 μM EGCG induced a trend of further decline in the respiratory control ratio beyond that observed upon tBHP exposure alone. EGCG had no effect on MMP and no effect, in concentrations up to 50 μM, on mitochondrial calcium retention capacity. tBHP led to a decline in both MMP and mitochondrial retention capacity for calcium; these effects were not changed by pretreatment with EGCG. In addition, EGCG dose-dependently enhanced hydrogen peroxide formation in a cell- and mitochondria-free medium. Conclusion. Moderate nontoxic doses of EGCG were not able to protect rat liver mitochondria and hepatocytes from tBHP-induced mitochondrial dysfunction.

• MeSH
• Hepatocytes cytology   drug effects   metabolism   MeSH
• Mitochondria, Liver drug effects   metabolism   MeSH
• Catechin analogs & derivatives   pharmacology   MeSH
• Rats MeSH
• Cells, Cultured MeSH
• Membrane Potential, Mitochondrial drug effects   MeSH
• Hydrogen Peroxide metabolism   MeSH
• Rats, Wistar MeSH
• Oxygen Consumption drug effects   MeSH
• tert-Butylhydroperoxide toxicity   MeSH
• Calcium metabolism   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• epigallocatechin gallate MeSH Browser
• Catechin MeSH
• Hydrogen Peroxide MeSH
• tert-Butylhydroperoxide MeSH
• Calcium MeSH

Oxidative stress and mitochondrial dysfunction play an important role in the pathogenesis of nonalcoholic fatty liver disease and toxic liver injury. The present study was designed to evaluate the effect of exogenous inducer of oxidative stress (tert-butyl hydroperoxide, tBHP) on nonfatty and steatotic hepatocytes isolated from the liver of rats fed by standard and high-fat diet, respectively. In control steatotic hepatocytes, we found higher generation of ROS, increased lipoperoxidation, an altered redox state of glutathione, and decreased ADP-stimulated respiration using NADH-linked substrates, as compared to intact lean hepatocytes. Fatty hepatocytes exposed to tBHP exert more severe damage, lower reduced glutathione to total glutathione ratio, and higher formation of ROS and production of malondialdehyde and are more susceptible to tBHP-induced decrease in mitochondrial membrane potential. Respiratory control ratio of complex I was significantly reduced by tBHP in both lean and steatotic hepatocytes, but reduction in NADH-dependent state 3 respiration was more severe in fatty cells. In summary, our results collectively indicate that steatotic rat hepatocytes occur under conditions of enhanced oxidative stress and are more sensitive to the exogenous source of oxidative injury. This confirms the hypothesis of steatosis being the first hit sensitizing hepatocytes to further damage.

• MeSH
• Diet, High-Fat MeSH
• Glutathione metabolism   MeSH
• Hepatocytes drug effects   metabolism   MeSH
• Rats MeSH
• Cells, Cultured MeSH
• L-Lactate Dehydrogenase metabolism   MeSH
• Malondialdehyde metabolism   MeSH
• Membrane Potential, Mitochondrial drug effects   MeSH
• Non-alcoholic Fatty Liver Disease metabolism   pathology   MeSH
• Oxidative Stress drug effects   MeSH
• Lipid Peroxidation drug effects   MeSH
• Rats, Wistar MeSH
• Reactive Oxygen Species metabolism   MeSH
• tert-Butylhydroperoxide toxicity   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Glutathione MeSH
• L-Lactate Dehydrogenase MeSH
• Malondialdehyde MeSH
• Reactive Oxygen Species MeSH
• tert-Butylhydroperoxide MeSH