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Effects of bedding substrates on microsomal enzymes in rabbit liver

Dawn Ruben1, Nicole Muratore, Scott Pin

  • 1Johns Hopkins University, School of Medicine, Baltimore, MD, USA.

Journal of the American Association for Laboratory Animal Science : JAALAS
|May 10, 2007
PubMed

Insights

Pine shavings and paper bedding do not induce cytochrome P450 (CYP450) enzymes in rabbits. This study found no significant changes in CYP450 3A or 2B activity when rabbits were housed on these common substrates.

Area of Science:

  • Pharmacology
  • Toxicology
  • Animal Science

Background:

  • Softwood beddings are known to induce microsomal enzymes in rodents.
  • Limited research exists on the effects of bedding substrates on microsomal enzyme induction in rabbits.
  • Cytochrome P450 (CYP450) enzymes, particularly CYP3A and CYP2B, are crucial for drug metabolism.

Purpose of the Study:

  • To investigate whether common bedding substrates (pine shavings, recycled paper) induce CYP450 3A and 2B enzymes in rabbits.
  • To assess the impact of noncontact bedding exposure on hepatic microsomal enzyme activity in rabbits.

Main Methods:

  • Rabbits were housed on pine shavings, recycled paper, or no substrate for up to 14 days.
  • Positive controls received intraperitoneal rifampin or phenobarbital to induce CYP450 enzymes.
  • Liver microsomes were analyzed for CYP3A and CYP2B activity using specific enzyme assays.

Main Results:

  • No statistically significant induction of CYP450 3A or 2B enzymes was observed in rabbits exposed to pine shavings or paper bedding.
  • Enzyme activity levels in rabbits on bedding substrates did not reach the levels seen in positive controls.
  • Exposure to pine shavings or paper as noncontact bedding did not significantly alter key drug-metabolizing enzymes.

Conclusions:

  • Pine shavings and recycled paper, when used as noncontact bedding, do not induce CYP450 3A or 2B enzymes in rabbits.
  • These findings suggest that common bedding materials are unlikely to significantly affect rabbit drug metabolism via these specific CYP450 pathways.
  • Further research may explore longer exposure durations or different bedding types.

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