An integrated functional genomic study of acute phenobarbital exposure in the rat.
BACKGROUND
Non-genotoxic carcinogens are notoriously difficult to identify as they do not damage DNA directly and have diverse modes of action, necessitating long term in vivo studies. The early effects of the classic rodent non-genotoxic hepatocarcinogen phenobarbital have been investigated in the Fisher rat using a combination of metabolomics and transcriptomics, to investige early stage mechanistic changes that are predictive of longer term pathology.


RESULTS
Liver and blood plasma were profiled across 14 days, and multivariate statistics used to identify perturbed pathways. Both metabolomics and transcriptomics detected changes in the liver which were dose dependent, even after one day of exposure. Integration of the two datasets associated perturbations with specific pathways. Hepatic glycogen was decreased due to a decrease in synthesis, and plasma triglycerides were decreased due to an increase in fatty acid uptake by the liver. Hepatic succinate was increased and this was associated with increased heme biosynthesis. Glutathione synthesis was also increased, presumably in response to oxidative stress. Liquid Chromatography Mass Spectrometry demonstrated a remodeling of lipid species, possibly resulting from proliferation of the smooth endoplasmic reticulum.


CONCLUSIONS
The data fusion of metabolomic and transcriptomic changes proved to be a highly sensitive approach for monitoring early stage changes in altered hepatic metabolism, oxidative stress and cytochrome P450 induction simultaneously. This approach is particularly useful in interpreting changes in metabolites such as succinate which are hubs of metabolism.
Waterman
Claire L
CL
Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
Currie
Richard A
RA
Cottrell
Lisa A
LA
Dow
Jacky
J
Wright
Jayne
J
Waterfield
Catherine J
CJ
Griffin
Julian L
JL
D000818:Animals; D016000:Cluster Analysis; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D020869:Gene Expression Profiling; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D055442:Metabolome; D015999:Multivariate Analysis; D018384:Oxidative Stress; D010634:Phenobarbital / Q000633:toxicity*; D010949:Plasma / Q000187:drug effects / Q000378:metabolism; D025341:Principal Component Analysis; D051381:Rats; D011916:Rats, Inbred F344
D003577:Cytochrome P-450 Enzyme System; D010634:Phenobarbital