description
Circadian entrainment is a fundamental property by which the period of the internal biological clock is entrained by recurring exogenous signals, such that the organism's endocrine and behavioral rhythms are synchronized to environmental cues. In mammals, a master clock is located in the suprachiasmatic nuclei (SCN) of the hypothalamus and may synchronize circadian oscillators in peripheral tissues. Light signal is the dominant synchronizer for master SCN clock. Downstream from the retina, glutamate and PACAP are released and trigger the activation of signal transduction cascades, including CamKII and nNOS activity, cAMP- and cGMP-dependent protein kinases, and mitogen-activated protein kinase (MAPK). Of non-photic entrainment, important phase shifting capabilities have been found for melatonin, which inhibits light-induced phase shifts through inhibition of adenylate cyclase (AC). Multiple entrainment pathways converge into CREB regulation. In turn, phosphorylated CREB activates clock gene expression

external resources
NCBI:698773
KEGG:hsa04713
PUBMED:15016477
PUBMED:12700026
PUBMED:20605968
PUBMED:15813931
PUBMED:15930378
PUBMED:12573527
PUBMED:17586087
PUBMED:20664079
PUBMED:17646042
PUBMED:17167088
PUBMED:16217123
PUBMED:11294753
PUBMED:19109992
PUBMED:10446325
PUBMED:10208575
PUBMED:11086993
PUBMED:19449447

genes
ADCY1 , ADCY2 , ADCY3 , ADCY5 , ADCY6 , ADCY7 , ADCY8 , ADCY9 , ADCYAP1R1 , CACNA1C , CACNA1D , CALM1 , CALM2 , CALM3 , CALML3 , CAMK2A , CAMK2B , CAMK2D , CAMK2G , CREB1 , FOS , GNAI1 , GNAI2 , GNAI3 , GNAO1 , GNAQ , GNAS , GNB1 , GNB2 , GNB3 , GNG3 , GNG4 , GNG5 , GNG7 , GNG10 , GNG11 , GNGT1 , GNGT2 , GRIA1 , GRIA2 , GRIA3 , GRIA4 , GRIN1 , GRIN2A , GRIN2B , GRIN2C , GRIN2D , GUCY1A2 , GUCY1A1 , GUCY1B1 , ITPR1 , ITPR3 , KCNJ3 , KCNJ5 , KCNJ6 , KCNJ9 , MTNR1A , MTNR1B , NOS1 , PER1 , PLCB2 , PLCB3 , PLCB4 , PRKACA , PRKACB , PRKACG , PRKCA , PRKCB , PRKCG , PRKG1 , PRKG2 , MAPK1 , MAPK3 , RYR1 , RYR2 , RYR3 , PER3 , PER2 , CACNA1I , CACNA1H , CACNA1G , RPS6KA5 , NOS1AP , GNB5 , PLCB1 , RASD1 , GNG13 , CALML5 , GNG2 , ADCY10 , GNG12 , GNB4 , CALML4 , GNG8 , CALML6 , ADCY4 ,