The circadian system of c-fos deficient mice.
We examined the role of c-fos in the synchronization of circadian rhythms to environmental light cycles using a line of gene-targeted mice carrying a null mutation at this locus. Circadian locomotor rhythms in mutants had similar periods as wild-type controls but took significantly longer than controls to entrain to 12:12 light-dark cycles. Light-induced phase shifts of rhythms in constant dark were attenuated in mutants although the circadian timing of phase delays and advances was not changed. A functional retinohypothalamic projection was indicated from behavioral results and light-induced jun-B expression in the SCN. The results indicate that while c-fos activation is not an absolute requirement for rhythm generation nor photic responses, it is required for normal entrainment of the mammalian biological clock.
Honrado
G I
GI
Department of Psychology, University of Toronto, Ontario, Canada.
Johnson
R S
RS
Golombek
D A
DA
Spiegelman
B M
BM
Papaioannou
V E
VE
Ralph
M R
MR
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D007031:Hypothalamus / Q000033:anatomy & histology / Q000502:physiology; D007150:Immunohistochemistry; D008027:Light; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009154:Mutation; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics*; D051381:Rats; D012160:Retina / Q000033:anatomy & histology / Q000502:physiology; D014660:Vasoactive Intestinal Peptide / Q000096:biosynthesis; D014795:Visual Pathways / Q000033:anatomy & histology / Q000502:physiology
D016760:Proto-Oncogene Proteins c-fos; D014660:Vasoactive Intestinal Peptide