Circadian timekeeping in BALB/c and C57BL/6 inbred mouse strains

Abstract

Circadian rhythms of locomotion (wheel-running activity) in 12 inbred mouse strains were recorded for interstrain differences in tau DD, the endogenous (free-running) period of the circadian pacemaker measured in constant environmental darkness. The results indicate that 1 or more genetic loci influence the value of tau DD, and a large (50 min) difference in mean tau DD between 2 of the strains, BALB/cByJ and C57BL/6J, allowed further characterization of the origins and inheritance of the polymorphic expression of this circadian pacemaker property. The interstrain difference in mean tau DD was associated with an interstrain difference in light-induced shifts of the phase of the free-running locomotor rhythm; the BALB/c strain (with the shorter mean tau DD) displayed relatively fewer advance phase shifts. Neither the history of previous light exposure, albinism, nor elevated circulating testosterone levels could account for the interstrain difference in mean tau DD. The value of tau DD based on the circadian rhythm of drinking activity (with the running wheel removed) was longer than that based on locomotion; this discrepancy was significantly greater and more variable in BALB/c than in C57BL/6 mice, though the interstrain difference in mean tau DD could not be attributed entirely to this effect. Reciprocal F1 hybrids of BALB/c x C57BL/6 matings revealed dominance of the C57BL/6 genotype, no sex linkage, and a significant (but small) maternal effect. Examination of CXB recombinant inbred strains provided no support for the hypothesis of monogenic inheritance. Further study of inherited differences in the BALB/c and C57BL/6 strains may be a useful noninvasive experimental approach for investigation of the neurobiological substrates of circadian rhythmicity.

Feeding Cues Alter Clock Gene Oscillations and Photic Responses in the Suprachiasmatic Nuclei of Mice Exposed to a Light/Dark Cycle

“…During most of the subjective day (pZT0 -pZT6), light exposure led to negligible behavioral phase shifts in control mice. Unexpectedly, compared with other phase-response curves to light in mice (Schwartz and Zimmerman, 1990), phase advances were apparent at pZT9 in C3H mice fed ad libitum. The shape of the phase-response curve to light was dramatically changed in hypocalorie-fed mice ( p Ͻ 0.0001) (Figs.…”

Na V 1.1 channels are critical for intercellular communication in the suprachiasmatic nucleus and for normal circadian rhythms

“…A brief light pulse applied during the early subjective night is associated with a delay in the circadian pacemaker (20)(21)(22). WT mice showed a 2.8 h mean phase delay in wheel-running activity in response to a 30-min, 500-lux light pulse applied at circadian time 16 (CT16, with CT12 corresponding to the onset of locomotor activity) ( Fig.…”

Association between mammalian lifespan and circadian free-running period: the circadian resonance hypothesis revisited

“…These limitations might account for the lack of association between the phylogenetic independent contrasts in rodents (electronic supplementary material, figure S2). Nevertheless, interpretation of the results in the rodent and primate groups is aided by the concurrent relationship between tau and lifespan among strains of laboratory mice (figure 1), where highly accurate data for tau and lifespan are available (Schwartz & Zimmerman 1990). However, the contribution of strain-related pathology to lifespan cannot be excluded.…”