Characteristics of food-entrained circadian rhythms in rats during long-term exposure to constant light.
Rats possess a system of circadian oscillators that permit entrainment of circadian activity rhythms independently to 24 hr cycles of light-dark and food access. The nature of interactions between food- and light-entrainable oscillators was examined by observing the generation and persistence of food-entrained circadian rhythms in rats whose light-entrainable rhythms were eliminated by long-term exposure to constant light. Most of these rats showed a delayed generation of food-entrained rhythms and only one of eight animals showed persistence of food associated rhythms during a 4-day food deprivation test. Rats whose light-entrainable rhythms are eliminated by suprachiasmatic nuclei ablation show, in contrast, normal generation and persistence of food-entrained rhythms. The results suggested a disruptive influence of constant light on non-photic entrainment, possibly due to coupling forces between damped light-entrainable oscillators and the food-entrainable oscillators.
Mistlberger
R E
RE
Department of Physiology and Biophysics, Harvard Medical School, Boston, MA.
Houpt
T A
TA
Moore-Ede
M C
MC
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology / Q000528:radiation effects*; D005247:Feeding Behavior / Q000502:physiology / Q000528:radiation effects*; D005508:Food Deprivation / Q000502:physiology; D008027:Light; D008297:Male; D009043:Motor Activity / Q000502:physiology / Q000528:radiation effects; D051381:Rats; D011919:Rats, Inbred Strains