title: Circadian properties of anticipatory activity to restricted water access in suprachiasmatic-ablated hamsters.
abstract: This study provides evidence that anticipation of daily water access in hamsters is regulated by nonphotically entrainable circadian oscillators located outside of the suprachiasmatic nuclei (SCN). Intact and SCN-ablated hamsters receiving 2 h/day water access ate large meals (representing 17-55% of daily food intake) during the 2-h access time. Two of nine SCN-intact hamsters, five of five hamsters with partial SCN ablations, and seven of nine hamsters with total SCN ablations showed anticipatory wheel-running rhythms synchronized to water access time. These anticipation rhythms usually disappeared during subsequent ad libitum water access but reappeared when the hamsters were water deprived for 2 days. When the water restriction schedule was shortened to an 18-h interval in six SCN-ablated hamsters, an 18-h activity rhythm emerged that usually did not persist during water deprivation. When the schedule was lengthened to 30-h intervals, several hamsters showed 27- to 29-h rhythms that did not stably synchronize to water access time. These results indicate that hamsters, like rats, possess a non-SCN-based water- and/or food-entrainable, self-sustaining oscillator with circadian limits to entrainment.
authors.affiliation: Department of Psychology, Simon Fraser University, Burnaby, British Columbia, Canada.
authors.forename: R E
authors.initials: RE
authors.lastname: Mistlberger
mesh_terms: D000204:Activity Cycles; D000818:Animals; D002940:Circadian Rhythm; D006224:Cricetinae; D004435:Eating; D008297:Male; D009043:Motor Activity / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000502:physiology*; D013997:Time Factors; D014868:Water Deprivation