Circadian rhythms and the effect of glucocorticoids on expression of the clock gene period1 in canine peripheral blood mononuclear cells

Circadian rhythms have a periodicity of approximately 24 h and, in mammals, are regulated by clock genes. In this study, expression profiles of clock genes (per1, per2, clock, bmal1 and cry1) were investigated over a single 24 h period by real-time PCR in peripheral blood mononuclear cells (PBMCs) of healthy dogs and canine PBMCs treated in vitro and in vivo with glucocorticoids. Only pen 1 mRNA exhibited daily rhythms in canine PBMCs. Canine PBMCs cultured with dexamethasone in vitro had dose- and time-dependent increases in pen 1 mRNA expression. Intravenous injection of dexamethasone increased expression of pen l in canine PBMCs in vivo. Rhythmic expression of per1 in PBMCs could be used as a molecular marker for monitoring circadian rhythms and the effects of drugs on clock genes in dogs. (C) 2012 Elsevier Ltd. All rights reserved.