Spectral sensitivity of photoreceptors mediating phase-shifts of circadian rhythms in retinally degenerate CBA/J (rd/rd) and normal CBA/N (+/+)mice.
Light-dark cycles are the most important time cue for the circadian system to entrain the endogenous circadian clock to the environmental 24 h cycle. Although photic entrainment of circadian rhythms is mediated by the eye in mammals, photoreceptors implicated in circadian photoreception remain unknown. In our previous study, retinally degenerate CBA/J (rd/rd) mice were found to have lower circadian photosensitivity for phase-shifting the locomotor activity rhythms than normal CBA/N(+/+) mice. In the present study, the spectral sensitivity for phase-shifting the rhythms was examined in order to characterize the photopigments involved in circadian photoreception of these mice. The spectral sensitivity of CBA/J-rd/rd mice clearly fitted to the Dartnall nomogram for a retinal(1)-based pigment with a maximum at 480 nm, while the best fitted nomogram had a maximum at 500 nm in CBA/N- +/+ mice. These results suggest that circadian photopigments involved in CBA/J-rd/rd and CBA/N- +/+ mice may be different.
Yoshimura
T
T
Department of Animal Physiology, School of Agricultural Sciences, Nagoya University, Japan.
Ebihara
S
S
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D005127:Eye Color / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D009043:Motor Activity / Q000502:physiology; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000502:physiology*; D012162:Retinal Degeneration / Q000503:physiopathology*