Aschoff's rule in retinally degenerate mice.
Both retinally degenerate and wildtype mice lengthened the period of their free-running circadian rhythms and reduced the amount of wheel running when exposed to increasing levels of constant illumination, in accordance with Aschoff's rule. Decreased locomotor activity may contribute toward lengthening of period in bright light. However, the known effects of activity on free-running period are small compared to those obtained by changing illumination. This suggests that Aschoff's rule in mice is not dependent on changes in nonphotic input, but results from a direct effect of light on the circadian system. The sparing of Aschoff's rule in retinally degenerate mice is further evidence that circadian photoreception depends on mechanisms other than rods and cones.
Mrosovsky
N
N
Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada. mro@zoo.utoronto.ca
D000818:Animals; D002940:Circadian Rhythm; D008027:Light; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic / Q000502:physiology; D009043:Motor Activity / Q000502:physiology*; D010775:Photic Stimulation; D017440:Photoperiod; D012162:Retinal Degeneration / Q000503:physiopathology*; D014796:Visual Perception / Q000502:physiology