Postnatal ontogenesis of clock genes in mouse suprachiasmatic nucleus and heart.
BACKGROUND
The master clock within the hypothalamic suprachiasmatic nucleus (SCN) synchronizing clocks in peripheral tissues is entrained by the environmental condition, such as the light-dark (LD) cycle. The mechanisms of circadian clockwork are similar in both SCN and peripheral tissues. The aim of the present work was to observe the profiles of clock genes expression in mouse central and peripheral tissues within postnatal day 5 (P5). The daily expression of four clock genes mRNA (Bmal1, Per2, Cry1 and Rev-erb alpha) in mouse SCN and heart was measured at P1, P3 and P5 by real-time PCR.


RESULTS
All the studied mice clock genes began to express in a circadian rhythms manner in heart and SCN at P3 and P5 respectively. Interestingly, the daily rhythmic phase of some clock genes shifted during the postnatal days. Moreover, the expressions of clock genes in heart were not synchronized with those in SCN until at P5.


CONCLUSIONS
The data showed the gradual development of clock genes in SCN and a peripheral tissue, and suggested that development of clock genes differed between in the SCN and the heart. Judging from the mRNA expression, it was possible that the central clock synchronized the peripheral clock as early as P5.
Huang
Jie
J
Department of Physiology and Pathophysiology, Shanghai Medical College Fudan University, Shanghai 200032, PR China. drhua@126.com.
Lu
Chao
C
Chen
Sifen
S
Hua
Luchun
L
Qian
Ruizhe
R
D000818:Animals; D001683:Biological Clocks / Q000235:genetics; D056926:CLOCK Proteins / Q000096:biosynthesis*; D002467:Cell Nucleus / Q000378:metabolism*; D002940:Circadian Rhythm; D017931:DNA Primers / Q000235:genetics; D005786:Gene Expression Regulation; D008027:Light; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013493:Suprachiasmatic Nucleus / Q000254:growth & development* / Q000378:metabolism*; D013997:Time Factors
D017931:DNA Primers; D012333:RNA, Messenger; D056926:CLOCK Proteins