In vitro evidence for chronic alcohol and high glucose mediated increased oxidative stress and hepatotoxicity.
BACKGROUND
Hyperglycemia or alcoholism can lead to impaired liver functions. Cytochrome P450 2E1 (CYP2E1) is elevated in hyperglycemia or alcoholism and plays a critical role in generating oxidative stress in the cell.


METHODS
In the present study, we have used VL-17A cells that overexpress the alcohol metabolizing enzymes [alcohol dehydrogenase (ADH) and CYP2E1] to investigate the toxicity due to ethanol (EtOH) plus high glucose. Toxicity was assessed through viability assay and amount of acetaldehyde adduct formation. Oxidative stress parameters included measuring reactive oxygen species (ROS) levels and malondialdehyde adduct formation. Apoptosis was determined through caspase-3 activity, Annexin V- Propidium iodide staining, and changes in mitochondrial membrane potential. The effects of antioxidants and specific inhibitors of ADH and CYP2E1 on cell viability and ROS levels were also studied.


RESULTS
When present together, EtOH plus high glucose-treated VL-17A cells exhibited greater oxidative stress and toxicity than other groups. Apoptosis was observed in liver cells treated with the toxins, and the EtOH plus high glucose-treated VL-17A cells exhibited apoptosis to the largest extent. A distinct and graded increase in CYP2E1 level occurred in the different groups of VL-17A cells. Further, antioxidants or inhibitors of ADH and CYP2E1 were effective in decreasing the observed oxidative stress and toxicity.


CONCLUSIONS
The combined oxidative insult due to alcohol plus high glucose leads to greater liver injury, which may prove to be a timely warning for the injurious effects of alcohol consumption in diabetics.
Life Science Division, AU-KBC Research Centre, MIT Campus of Anna University, Chromepet, Chennai, India.
Karthikeyan
K
Chandrasekaran
Kavitha
K
Swaminathan
S
S
Mathan Kumar
Dahn L
DL
Clemens
Aparajita
A
Dey
D000079:Acetaldehyde / Q000378:metabolism; D000426:Alcohol Dehydrogenase / Q000187:drug effects / Q000378:metabolism*; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000187:drug effects / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival; D002492:Central Nervous System Depressants / Q000633:toxicity*; D019392:Cytochrome P-450 CYP2E1 / Q000187:drug effects / Q000378:metabolism*; D000431:Ethanol / Q000633:toxicity*; D005947:Glucose / Q000633:toxicity*; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013549:Sweetening Agents / Q000633:toxicity*
D000975:Antioxidants; D002492:Central Nervous System Depressants; D017382:Reactive Oxygen Species; D013549:Sweetening Agents; D000431:Ethanol; D000426:Alcohol Dehydrogenase; D019392:Cytochrome P-450 CYP2E1; D053148:Caspase 3; D000079:Acetaldehyde; D005947:Glucose