title: Diurnal difference in CAR mRNA expression.
abstract: BACKGROUND: The constitutive androstane receptor (CAR, NR1I3) plays a key role in the transcriptional activation of genes that encode xenobiotic/steroid and drug metabolizing enzymes. RESULTS: The expression of CAR mRNA throughout the circadian rhythm is reported for the first time in phase with the clock gene Bmal1 and in antiphase with the clock-controlled gene Rev-erbalpha mRNAs, with a peak at Zeitgeber time (ZT) 20 and a trough at ZT8, and a peak/trough ratio of 2.0. The diurnal difference in CAR mRNA expression might underlie the 1.7-fold difference in the magnitude of the PB-dependent induction of CYP2B1/2 mRNA. CONCLUSION: The circadian oscillation of xenosensor gene CAR mRNA expression is partially responsible for chronopharmacokinetics and chronopharmacology in disease.
authors.affiliation: Faculty of Pharmaceutical Sciences, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan. yinouye@phar.toho-u.ac.jp
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Kanno
authors.forename: Satoshi
authors.initials: S
authors.lastname: Otsuka
authors.forename: Takuya
authors.initials: T
authors.lastname: Hiromasa
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nakahama
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Inouye