To understand how mammalian herbivores process plant secondary compounds, w
e examined differences in expression of biutransformation enzyme mRNAs amon
g populations of wild woodrats (Neotoma lepida) and laboratory rats. We com
pared expression of mRNAs for 10 biotransforming enzymes in five families (
CYP, mEH, QOR, GST, and UGT) by using Northern blot analysis. We found sign
ificant differences in eight of 10 mRNAs tested. We suggest that the differ
ences in mRNA expression among populations of woodrats and laboratory rats
may be due to differences in the secondary compound composition of their di
ets. Our results provide background for future studies of detoxification st
rategies in mammalian herbivores that combine pharmacological techniques wi
th an ecological perspective.