TITLE:
Diurnal Variation of Nuclear Receptors in Mice with or without Fasting
AUTHORS:
Atsushi Kawase, Tetsuya Ohgami, Iho Yoshida, Yu Tsunokuni, Masahiro Iwaki
KEYWORDS:
CAR; Circadian Rhythm; Diurnal Variation; Fasting; Nuclear Receptor; PXR
JOURNAL NAME:
Pharmacology & Pharmacy,
Vol.4 No.2,
April
18,
2013
ABSTRACT: Nuclear receptors such as pregnane X
receptor (PXR) and constitutive androstane receptor (CAR) regulate the transcription
of transporter and cytochrome P450 (CYP). The diurnal variation was observed in
some transporters regulated by nuclear receptors. We investigated whether
diurnal variation in PXR and CAR exists in mice. We also examined the effect of
food intake on the diurnal rhythm of hepatic PXR and CAR using fed and fasted
mice. In liver and small intestine of fed mice, the mRNA levels of PXR and CAR
were unchanged between 7:00 AM and 7:00 PM. In contrast to fed mice, fasting
mice partly exhibited the diurnal variation in PXR, not in CAR. The mRNA levels
of PXR at 7:00 AM were significantly higher than that those at 7:00 PM in liver
of fasting mice. These results indicated the different effects of fasting in mice
on diurnal variation of PXR in each tissue.