Light regulates Homer mRNA expression in the rat suprachiasmatic nucleus.
The hypothalamic suprachiasmatic nucleus (SCN) of the mammal is the circadian pacemaker responsible for generation of circadian rhythms. Several immediate-early genes are expressed in the SCN by light stimuli which induce phase shifts of animal activity rhythms. In the present study, we investigated whether Homer, a PDZ-like protein which is rapidly induced following synaptic activation, mRNA expression is regulated by light in rat SCN. Homer mRNA expression in the SCN of rat killed at 4 h after onset of the light and dark phases was very low. One hour light stimuli during the subjective night dramatically induced Homer mRNA expression in the ventrolateral portion of the SCN, whereas light stimuli during the subjective light phase did not. This finding implies that Homer may be involved in the photic entrainment of the circadian clock.
Park
H T
HT
Department of Anatomy, College of Medicine, Inje University, Pusan, South Korea.
Kang
E K
EK
Bae
K W
KW
D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis*; D002940:Circadian Rhythm; D003624:Darkness; D005786:Gene Expression Regulation / Q000528:radiation effects; D000072233:Homer Scaffolding Proteins; D017403:In Situ Hybridization; D008027:Light; D008297:Male; D009479:Neuropeptides / Q000096:biosynthesis*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013493:Suprachiasmatic Nucleus / Q000378:metabolism* / Q000528:radiation effects; D014158:Transcription, Genetic / Q000528:radiation effects*
D002352:Carrier Proteins; D000072233:Homer Scaffolding Proteins; D009479:Neuropeptides; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger