Effects of caffeine on circadian phase, amplitude and period evaluated in cells in vitro and peripheral organs in vivo in PER2::LUCIFERASE mice

• Published in: British journal of pharmacology Vol. 171; no. 24; pp. 5858 - 5869
• Main Authors: Narishige, Seira, Kuwahara, Mari, Shinozaki, Ayako, Okada, Satoshi, Ikeda, Yuko, Kamagata, Mayo, Tahara, Yu, Shibata, Shigenobu
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.12.2014; BlackWell Publishing Ltd
• Subjects: Animals; Bioluminescence; Caffeine; Caffeine - pharmacology; Calcium signalling; Central Nervous System Stimulants - pharmacology; Circadian rhythm; Circadian Rhythm - drug effects; Circadian rhythms; Cyclic AMP; Fibroblasts - drug effects; Food intake; Gene Knock-In Techniques; In Vitro Techniques; Kidney - drug effects; Liver - drug effects; Luciferases - genetics; Mice; Period 2 protein; Period Circadian Proteins - drug effects; Period Circadian Proteins - genetics; Research Papers; Suprachiasmatic nucleus
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/bph.12890

Background and Purpose Caffeine is one of the most commonly used psychoactive substances. Circadian rhythms consist of the main suprachiasmatic nucleus (SCN) clocks and peripheral clocks. Although caffeine lengthens circadian rhythms and modifies phase changes in SCN‐operated rhythms, the effects on caffeine on the phase, period and amplitude of peripheral organ clocks are not known. In addition, the role of cAMP/Ca2+ signalling in effects of caffeine on rhythm has not been fully elucidated. Experimental Approach We examined whether chronic or transient application of caffeine affects circadian period/amplitude and phase by evaluating bioluminescence rhythm in PER2::LUCIFERASE knock‐in mice. Circadian rhythms were monitored in vitro using fibroblasts and ex vivo and in vivo for monitoring of peripheral clocks. Key Results Chronic application of caffeine (0.1–10 mM) increased period and amplitude in vitro. Transient application of caffeine (10 mM) near the bottom of the decreasing phase of bioluminescence rhythm caused phase advance in vitro. Caffeine (0.1%) intake caused a phase delay under light–dark or constant dark conditions, suggesting a period‐lengthening effect in vivo. Caffeine (20 mg·kg−1) at daytime or at late night‐time caused phase advance or delay in bioluminescence rhythm in the liver and kidney respectively. The complicated roles of cAMP/Ca2+ signalling may be involved in the caffeine‐induced increase of period and amplitude in vitro. Conclusions and Implications Caffeine affects circadian rhythm in mice by lengthening the period and causing a phase shift of peripheral clocks. These results suggest that caffeine intake with food/drink may help with food‐induced resetting of peripheral circadian clocks.