Fig.4. Spatial and temporal distribution of Per1 gene expression in the SCN, throughout the L/D-cycle.

Per1 gene expression is shown for ad libitum fed animals (AL), for ad libitum fed animals that had been phase-shifted (8-hours) 5 days earlier (ALs), and for animals on a restricted-feeding protocol that had been phase-shifted 5 days earlier (RFs). Per1 gene expression was revealed by the non-radioactive immuno-in situ hybridization technique (with the help of Dr. Hugues Dardente, in the laboratory of Dr. Paul Pévet). Gray and black bars on the left side of the figures indicate light and dark portions of the L/D-cycle. Animals on restricted feeding (RF) had daily access to food from ZT4–6. The 8-h phase-advance of the L/D-cycle was realized by shutting down the light at ZT4. The RF animals had been on the RF protocol for 4 weeks before the phase-shift. From the first day of the shift, the animals were provided with food ad libitum. Starting at ZT10 on day 5 after the shift (D5) and ZT2 for the non-shifted groups, the animals of the 4 groups were maintained in constant darkness under red-dim-light until the end of the experiment. The animals of the AL, ALs, and RFs groups were perfused every 4-hours at six different time points starting at CTs14 on D5 (CTs14 indicating CT14 after the shift and corresponding to ZT6 in non-shifted time). For further details see the thesis of Stephanie Perreau-Lenz (2004).