Fig. 1.

Caffeine and lithium lengthen circadian period of PER2::LUC expression in neuronal cells. (A) Representative detrended data for PER2::LUC neuronal cells incubated with DMSO vehicle (dashed line) or 5 mM caffeine (solid line). (B) Representative detrended data for PER2::LUC neuronal cells incubated with DMSO vehicle (dashed line) or 20 mM lithium (solid line). (C) Effects of caffeine or lithium on period of rhythmic PER2::LUC expression in neuronal cells. Distance between peaks 1 and 3 was multiplied by 0.5 to determine period length. Circadian period of PER2::LUC bioluminescence oscillations was increased by either caffeine or lithium. *P<0.01 vs. vehicle; Dunnett’s test. All values are expressed as means±SEM (n=3 per group).