Non-photic phase resetting of Dexras1 deficient mice: a more complicated story.
Recently, it has been reported that mice deficient for Dexras1 have a diminished phase-shifting response to photic stimuli but an enhanced response to non-photic stimuli; the latter is of additional interest in that mice generally show relatively weak and unreliable responses to non-photic events. Therefore, in situations in which both photic and non-photic stimuli are present, control of circadian rhythms, relative to wild-types, should tip toward non-photic stimuli in Dexras1(-/-) mice. However, we detected no differences in an experiment in which photic and non-photic entraining agents were presented 180 degrees out of phase, i.e. were in conflict with each other. Furthermore, Dexras1(-/-) and wild-type mice did not differ in non-photic phase shifting to a pulse of confinement in a novel running wheel. Suppression of locomotion by light (masking effect) did not differ between the genotypes, indicating that the photoreceptor input to the non-image forming system is intact. The circadian phenotype of Dexras1(-/-) mice appears to be more complicated than previously thought.
Dallmann
R
R
Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA, USA. robert@dallmanns.de
Mrosovsky
N
N
D000818:Animals; D001522:Behavior, Animal; D002940:Circadian Rhythm / Q000235:genetics*; D004307:Dose-Response Relationship, Radiation; D005106:Exploratory Behavior / Q000502:physiology; D008124:Locomotion / Q000235:genetics*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D010775:Photic Stimulation / Q000379:methods; D018631:ras Proteins / Q000172:deficiency* / Q000235:genetics / Q000502:physiology
C498511:Rasd1 protein, mouse; D018631:ras Proteins