Fig. 3.

PPARβ/δ expression in the hamster SCN varies with the light condition. The PPARβ/δ expression in the SCN of hamsters maintained under either the light–dark (LD) cycle or constant darkness (DD) was compared in hamsters killed at two time points of the light and dark phase showing significant difference under the LD cycle. a The variation in the number of immunoreactive neurons between ZT06 and ZT14 was abolished under DD; b day-night variations of mRNA expression were still present under DD (i.e., between CT06 and CT18). These results indicate that the PPARβ/δ protein expression is modulated by the presence of light. The values are presented as the mean ± SEM (n = 4 or 5). a, b Significant difference between the different killing times (p < 0.05, one-way ANOVA). Above the bars representative diagram of PPARβ/δ distribution. ZT Zeitgeber time, under the LD cycle, the light/dark transition is conventionally defined as ZT12; CT circadian time, under the DD at the onset of activity is defined as CT12