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Bioisomerization of lindane in rats
Journal of Environmental Pathology and Toxicology
|January 1, 1979
Summary
This study investigated lindane (gamma-hexachlorocyclohexane) bioisomerization in rats. Results indicate that bioisomerization does not significantly contribute to lindane metabolism, despite observed changes in liver enzymes and weight.
Area of Science:
- Environmental Toxicology
- Biochemistry
- Pharmacokinetics
Background:
- Lindane (gamma-hexachlorocyclohexane) use poses environmental concerns due to persistent, oncogenic alpha- and beta- isomers.
- A proposed mechanism for these residues is the bioisomerization of gamma-HCH to more stable isomers.
- Understanding lindane metabolism is crucial for assessing its environmental and health risks.
Purpose of the Study:
- To investigate the effect of dose and duration of gamma-hexachlorocyclohexane (lindane) exposure on its proposed bioisomerization in rats.
- To determine if lindane exposure leads to the formation of alpha- and beta-HCH isomers in vivo.
- To assess the correlation between lindane treatment and changes in liver enzyme activity and organ weights.
Main Methods:
- Weanling female Sprague-Dawley rats were fed diets containing 0, 130, 215, or 350 ppm gamma-HCH for up to 24 weeks.
- Animals were sacrificed at various time points (1-24 weeks) to analyze tissue samples for HCH isomers.
- In vitro dechlorinase activity and liver/body weight ratios were measured to assess metabolic and toxicological effects.
Main Results:
- No significant differences in food consumption or body weights were observed across treatment groups.
- In vitro dechlorinase activity increased significantly with lindane treatment duration.
- Elevated liver/body weight ratios were noted in rats fed higher doses of lindane, except at 4 weeks.
- No beta-HCH was detected; alpha-HCH levels were attributable to trace contamination, and hepatic HCH content decreased with treatment duration.
Conclusions:
- Bioisomerization of gamma-hexachlorocyclohexane (lindane) to alpha- and beta- isomers does not appear to play a significant role in its metabolism by rats.
- Observed increases in dechlorinase activity and liver weight suggest adaptive metabolic responses to lindane exposure.
- The study refutes the bioisomerization hypothesis as a major pathway for lindane residue formation in this model.