Modification of chemical toxicity by selenium deficiency

Area of Science:

• Biochemistry
• Toxicology
• Nutritional Science

Background:

• Selenium deficiency induces significant hepatic metabolic changes in rats.
• Key alterations include decreased glutathione peroxidase and increased glutathione S-transferase activity.
• These metabolic shifts can influence the toxicity of various xenobiotics.

Purpose of the Study:

• To investigate the impact of selenium deficiency on chemical toxicity in rats.
• To elucidate the role of selenium in protecting against specific toxic compounds.
• To explore selenium's antioxidant defense mechanisms beyond glutathione peroxidase.

Main Methods:

• Rats were subjected to selenium deficiency or control diets.
• Exposure to hepatotoxicants (iodipamide, acetaminophen, aflatoxin B1) and redox cycling compounds (nitrofurantoin, diquat) was assessed.
• Measurements included glutathione peroxidase and S-transferase activities, glutathione synthesis rates, and indicators of lipid peroxidation (ethane production).

Main Results:

• Selenium deficiency reduced the toxicity of compounds binding to glutathione S-transferase (iodipamide, acetaminophen, aflatoxin B1).
• Conversely, selenium deficiency increased the toxicity of redox cycling compounds like nitrofurantoin and diquat, correlating with lipid peroxidation.
• Increased oxygen tension mitigated diquat-induced lipid peroxidation in both selenium-deficient and control rats.

Conclusions:

• Selenium deficiency has differential effects on chemical toxicity, decreasing some while exacerbating others.
• The findings suggest selenium possesses oxidant defense functions independent of glutathione peroxidase.
• Oxygen plays a protective role against diquat-induced lipid peroxidation.