Figure 5.

Circadian gene expression in liver after food-entrainment. (A) Mice kept under a LD regimen (lights on at 6 a.m., lights off at 6 p.m.) were fed exclusively during the day for seven consecutive days. On the morning of the eighth day, food was not given back, and animals were sacrificed at 4-h intervals during the following 36 h. Thus, after daytime feeding the mice were starved between 12 and 48 h before they were killed for the analysis of the various mRNAs (depicted to the left of the panels). (B) mRNA levels obtained for starved mice (panel A) were quantified and normalized to Tbp mRNA. The times at which zenith mRNA levels were reached in daytime- and nighttime-fed mice are indicated by black and white arrows, respectively (see Fig. 1). (C) Per1 and Per2 mRNA accumulation in the suprachiasmatic nucleus (SCN) of starved animals (see panel A) has been determined by in situ hybridization to coronal brain sections as described in Figure 1. Note that daytime feeding followed by starvation has no effect on circadian Per1 and Per2 mRNA accumulation in the SCN.