“Induction of Drug-Metabolizing Enzymes in Liver Microsomes of Mice and Rats by Softwood Bedding”, 1967-09-01 (; similar):
Induction of three drug-metabolizing enzymes occurred in liver microsomes of mice and rats kept on softwood bedding of either red cedar, white pine, or ponderosa pine. This induction was reversed when animals were placed on hardwood bedding composed of a mixture of beech, birch, and maple. Differences in the capacity of various beddings to induce may partially explain divergent results of studies on drug-metabolizing enzymes. The presence of such inducing substances in the environment may influence the pharmacologic responsiveness of animals to a wide variety of drugs.
[1975 description:
Even the animal experimenter is not exempt from problems of interaction. (I am indebted to Neal Miller for the following example.) Investigators checking on how animals metabolize drugs found that results differed mysteriously from laboratory to laboratory. The most startling inconsistency of all occurred after a refurbishing of a National Institutes of Health (NIH) animal room brought in new cages and new supplies. Previously, a mouse would sleep for about 35 minutes after a standard injection of hexobarbital. In their new homes, the NIH mice came miraculously back to their feet just 16 minutes after receiving a shot of the drug. Detective work proved that red-cedar bedding made the difference, stepping up the activity of several enzymes that metabolize hexobarbital. Pine shavings had the same effect. When the softwood was replaced with birch or maple bedding like that originally used, drug response came back in line with previous experience (1967).
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