Oxidative stress in liver of mice exposed to arsenic-contaminated water.
BACKGROUND
Oxidative stress has been implicated in the initiation of hepatic damage caused by various agents. Not much data on oxidative stress in liver in chronic arsenic exposure are available in the literature. We therefore studied this aspect in a murine model.


METHODS
BALB/c mice were given arsenic-contaminated (3.2 mg/L) or arsenic-free (< 0.01 mg/L, control) drinking water ad libitum. Batches of mice were sacrificed after 2 and 4 months, and blood samples and liver tissue were collected. Liver histology was examined and levels of hepatic reduced glutathione (GSH), malondialdehyde, and enzymes of the antioxidant defense system in the liver tissue were determined. Arsenic content in liver tissues obtained at 4 months was estimated.


RESULTS
Two-month exposure to arsenic caused significant elevation of hepatic GSH (11.4 [0.8] micrograms/mg protein) compared to control mice (9.3 [0.4]; p < 0.01). Levels of enzymes related to GSH homeostasis were also elevated. At 4 months, hepatic GSH was significantly reduced (8.4 [0.5] micrograms/mg protein) when compared to control mice (9.3 [0.4]; p < 0.01). Arsenic content in the liver tissue after 4 months of exposure was significantly higher (0.40 [0.05] microgram/g) as compared to control mice (0.04 [0.04]; p < 0.01).


CONCLUSIONS
The results suggest that the antioxidant defense system in the liver of mice is activated after exposure to arsenic for 2 months. However, prolonged exposure to arsenic probably causes overuse failure of this system, which might result in initiation of biochemical injury to the liver.
Department of Gastroenterology, Institute of Post Graduate Medical Education and Research, Calcutta.
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Santra
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Maiti
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Chowdhury
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Mazumder
D000818:Animals; D001151:Arsenic / Q000009:adverse effects* / Q000494:pharmacology; D004195:Disease Models, Animal; D005982:Glutathione Transferase / Q000378:metabolism*; D008099:Liver / Q000187:drug effects* / Q000201:enzymology*; D008111:Liver Function Tests; D051379:Mice; D008807:Mice, Inbred BALB C; D018384:Oxidative Stress; D012016:Reference Values; D014877:Water Pollution, Chemical / Q000009:adverse effects*
D005982:Glutathione Transferase; D001151:Arsenic