Role of constitutive androstane receptor in the in vivo induction of Mrp3 and CYP2B1/2 by phenobarbital.
Phenobarbital (PB) induces the hepatic organic anion transporter, Mrp3. The present study tested the hypothesis that Mrp3 induction by PB is mediated by the constitutive androstane receptor (CAR). PB induction of Mrp3 and CYP2B was examined in lean and obese Zucker rats, male and female Wistar Kyoto (WKY) rats, HepG2 and mouse CAR-expressing HepG2 (g2car-3) cells; HepG2 and g2car-3 cells also were treated with 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP). In obese Zucker rat livers, total and nuclear CAR levels were markedly lower compared with lean rat livers, which correlated with the poor induction of CYP2B1/2 by PB in obese Zucker rats. Mrp3 induction by PB also was impaired in obese Zucker rat livers. Induction of Mrp3 by PB was similar in male and female WKY rat livers, despite the fact that CAR protein levels were significantly lower in female relative to male WKY rat livers. MRP3 levels in both HepG2 and g2car-3 cells were induced to a similar extent in the two cell lines by PB but not by TCPOBOP. In contrast, CYP2B6 levels were measurable and induced by TCPOBOP only in g2car-3 cells. In conclusion, data from WKY rats and HepG2 cells suggest that CAR does not play a key role in PB induction of Mrp3. Impaired induction of Mrp3 by PB in obese Zucker rats is not due solely to CAR deficiency. Interestingly, differences in the constitutive levels of Mrp3 were observed between obese and lean Zucker rats and between male and female WKY rats.
Division of Drug Delivery and Disposition, School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599-7360, USA.
Hao
H
Xiong
Kouichi
K
Yoshinari
Kim L R
KL
Brouwer
Masahiko
M
Negishi
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis*; D015153:Blotting, Western; D018929:Cell Culture Techniques; D002851:Chromatography, High Pressure Liquid; D000090702:Constitutive Androstane Receptor; D019362:Cytochrome P-450 CYP2B1 / Q000096:biosynthesis*; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D005656:Fungal Proteins / Q000096:biosynthesis*; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D010634:Phenobarbital / Q000494:pharmacology*; D011768:Pyruvate Dehydrogenase Complex; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011921:Rats, Inbred WKY; D011924:Rats, Zucker; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012269:Ribosomal Proteins / Q000096:biosynthesis*; D013250:Steroid Hydroxylases / Q000096:biosynthesis*; D014157:Transcription Factors / Q000502:physiology*
D000090702:Constitutive Androstane Receptor; D005656:Fungal Proteins; D011768:Pyruvate Dehydrogenase Complex; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D012269:Ribosomal Proteins; D014157:Transcription Factors; C067358:MRP-3 protein, Neurospora crassa; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; D019362:Cytochrome P-450 CYP2B1; C025619:steroid 16-beta-hydroxylase; D051047:Dihydrolipoyllysine-Residue Acetyltransferase; D010634:Phenobarbital