Persistence of a behavioral food-anticipatory circadian rhythm following dorsomedial hypothalamic ablation in rats

Department of Psychology, Simon Fraser University, Burnaby, British Columbia, Canada Submitted 14 December 2005 ; accepted in final form 5 January 2006 Circadian rhythms of behavior in rodents are regulated by a system of circadian oscillators, including a master light-entrainable pacemaker in the s...

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Bibliographic Details
Published in:American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2006-06, Vol.290 (6), p.R1527-R1534
Main Authors: Landry, G. J, Simon, M. M, Webb, I. C, Mistlberger, R. E
Format: Article
Language:English
Subjects:
Animals
Appetite Regulation - physiology
Behavior, Animal - physiology
Catheter Ablation
Circadian Rhythm - physiology
Dorsomedial Hypothalamic Nucleus - physiopathology
Dorsomedial Hypothalamic Nucleus - surgery
Eating - physiology
Eating - radiation effects
Food Deprivation - physiology
Hypothalamus - pathology
Hypothalamus - physiopathology
Light
Male
Rats
Rats, Sprague-Dawley
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Summary:Department of Psychology, Simon Fraser University, Burnaby, British Columbia, Canada Submitted 14 December 2005 ; accepted in final form 5 January 2006 Circadian rhythms of behavior in rodents are regulated by a system of circadian oscillators, including a master light-entrainable pacemaker in the suprachiasmatic nucleus that mediates synchrony to the day-night cycle, and food-entrainable oscillators located elsewhere that generate rhythms of food-anticipatory activity (FAA) synchronized to daily feeding schedules. Despite progress in elucidating neural and molecular mechanisms of circadian oscillators, localization of food-entrainable oscillators driving FAA remains an enduring problem. Recent evidence suggests that the dorsomedial hypothalamic nucleus (DMH) may function as a final common output for behavioral rhythms and may be critical for the expression of FAA (Gooley JJ, Schomer A, and Saper CB. Nat Neurosci 9: 398–407, 2006). To determine whether the reported loss of FAA by DMH lesions is specific to one behavioral measure or generalizes to other measures, rats received large radiofrequency lesions aimed at the DMH and were recorded in cages with movement sensors. Total and partial DMH ablation was associated with a significant attenuation of light-dark-entrained activity rhythms during ad libitum food access, because of a selective reduction in nocturnal activity. When food was restricted to a single 3-h daily meal in the middle of the lights-on period, all DMH and intact rats exhibited significant FAA. The rhythm of FAA persisted during a 48-h food deprivation test and reappeared during a 72-h deprivation test after ad libitum food access. The DMH is not the site of oscillators or entrainment pathways necessary for all manifestations of FAA, but may participate on the output side of this circadian function. food entrainment; food-anticipatory activity; food-entrainable oscillator Address for reprint requests and other correspondence: R. Mistlberger, Dept. of Psychology, Simon Fraser Univ., 8888 Univ. Drive, Burnaby, BC, Canada, V5A 1S6 (e-mail: mistlber{at}sfu.ca )
ISSN:0363-6119
1522-1490
DOI:10.1152/ajpregu.00874.2005