Fos expression in the suprachiasmatic nucleus during photic entrainment of circadian rhythms in retinally damaged rats.
The protein product of the immediate-early gene c-fos is expressed rhythmically in the shell region of the suprachiasmatic nucleus (SCN), the mammalian circadian clock. Recently, we found that exposure to an entraining light pulse caused a suppression of Fos expression in the SCN shell in rats. To study the hypothesis that suppression of Fos in the shell is a correlate of photic entrainment, we used rats that were treated with the retinal neurotoxin monosodium glutamate (MSG) during the neonatal period. In spite of retinal degeneration, MSG-treated rats entrained normally and displayed light-induced suppression of Fos within the SCN shell. These results support the view that light-induced suppression of Fos within the SCN shell is a cellular correlate of photic entrainment.
Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Quebec, H4B 1R6, Canada.
Christian
C
Beaulé
Jane
J
Barry-Shaw
Shimon
S
Amir
D000818:Animals; D000831:Animals, Newborn; D002940:Circadian Rhythm / Q000502:physiology / Q000528:radiation effects*; D003714:Denervation; D015536:Down-Regulation / Q000502:physiology / Q000528:radiation effects; D005260:Female; D008027:Light; D008297:Male; D009498:Neurotoxins; D010775:Photic Stimulation / Q000379:methods; D017440:Photoperiod; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism; D012160:Retina / Q000187:drug effects / Q000502:physiology*; D012162:Retinal Degeneration / Q000139:chemically induced / Q000503:physiopathology; D012970:Sodium Glutamate; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology / Q000528:radiation effects; D014795:Visual Pathways / Q000502:physiology*
D009498:Neurotoxins; D016760:Proto-Oncogene Proteins c-fos; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor; D012970:Sodium Glutamate