Activity and expression of various isoforms of uridine diphosphate glucuronosyltransferase are differentially regulated during hepatic regeneration in rats.
OBJECTIVE
Glucuronidation pathway is very important in the detoxification of endogenous and exogenous compounds. The objective of this study was to evaluate the activity and expression of various hepatic uridine diphosphate glucuronosyltransferases (UGTs) in rats at various time points after initiation of hepatic regeneration by partial hepatectomy (PHx).


METHODS
The mRNA expression of various UGTs was evaluated using real-time polymerase chain reaction (real-time PCR) with specific primers. The in vitro activity of UGTs was evaluated using different substrates such as estradiol (UGT1A1), acetaminophen (UGT1A6/7), morphine (UGT2B1), testosterone (UGT2B1/3/6), androsterone (UGT2B2), and (-)-borneol (UGT2B12).


RESULTS
Whereas the activity and mRNA expression of UGT1A1, UGT2B1, UGT2B1/3/6, UGT2B2, and UGT2B12 were lower, the activity and mRNA expression of UGT1A6/7 were preserved during hepatic regeneration. The mRNA expression of UGT2B8 was down-regulated, whereas the mRNA expression of UGT1A5 and UGT1A8 was not altered by PHx. The mRNA expression of UGT1A2 and UGT1A3 was increased during hepatic regeneration.


CONCLUSIONS
UGT-mediated drug-metabolizing ability of the liver was altered differentially in the regenerating rat liver. Individualized dosing regimen for different UGT substrates may be needed when using such substrates of these enzymes in patients with a regenerating liver, especially during the early postoperative period. However, the glucuronide conjugating capacity of the liver in the donor of a living donor liver transplantation is expected to completely return to normal with time after surgery.
Tian
Hui
H
Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
Ou
Junhai
J
Strom
Stephen C
SC
Venkataramanan
Raman
R
D000818:Animals; D015415:Biomarkers; D017931:DNA Primers; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics / Q000502:physiology; D014453:Glucuronosyltransferase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D006498:Hepatectomy; D015850:Interleukin-6 / Q000378:metabolism; D007527:Isoenzymes / Q000096:biosynthesis / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D008115:Liver Regeneration / Q000502:physiology*; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D015415:Biomarkers; D017931:DNA Primers; D015850:Interleukin-6; D007527:Isoenzymes; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D012313:RNA; D014453:Glucuronosyltransferase