Influence of a Time-Restricted Feeding Schedule on the Daily Rhythm of abcb1a Gene Expression and Its Function in Rat Intestine

P-glycoprotein (P-gp) is one of the ATP-binding cassette transporters and acts as an efflux pump for cytotoxic substances. P-gp mRNA expression and transporting activity show the daily rhythm and contribute to the chrono-pharmacokinetic profiles of many drugs. It is reported that the daily rhythm of abcb1a mRNA is regulated by a circadian clock-controlled output pathway. Time-restricted feeding is well known to shift the peripheral circadian phase of clock gene expression without changing the central clock function. This study was undertaken to examine the influence of a time-restricted feeding procedure during the light phase on the daily rhythms of abcb1a mRNA expression and P-gp activity. The abcb1a mRNA and P-gp activity showed a daily rhythm with a peak early in the dark phase in rat intestine under ad libitum feeding. Time-restricted feeding during the light phase shifted these rhythms to 12-h advance. The mRNA expression of clock genes (DBP and HLF, the transcript activators of abcb1a) also showed daily rhythms, and their phases were shifted by the time-restricted feeding procedure. The peak time of DBP mRNA expression was similar to that of abcb1a mRNA expression under ad libitum feeding and time-restricted feeding conditions. These results indicate that a time-restricted feeding procedure changes DBP mRNA expression, which in turn influences abcb1a mRNA expression and P-gp activity.