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In a rat model of night work, activity during the normal resting phase produces desynchrony in the hypothalamus.
MedLine Citation:
PMID:  21135158     Owner:  NLM     Status:  In-Process    
Internal synchrony among external cycles and internal oscillators allows adaptation of physiology to cyclic demands for homeostasis. Night work and shift work lead to a disrupted phase relationship between external time cues and internal rhythms, also losing internal coherence among oscillations. This process results in internal desynchrony (ID) in which behavioral, hormonal, and metabolic variables cycle out of phase. It is still not clear whether ID originates at a peripheral or at a central level. In order to determine the possible role of hypothalamic oscillators in ID, we explored with a rat model of "night work" daily rhythms of activity and clock gene expression in the hypothalamus. This study provides evidence that wakefulness and activity during the normal resting phase lead to a shift in the diurnal rhythms of c-Fos and induce a rhythm of PER1 in the arcuate and dorsomedial nucleus of the hypothalamus, both associated with metabolism and regulation of the sleep/wake cycle. Moreover, the number of orexin (ORX)-positive neurons and c-Fos in the perifornical area increased during the working period, suggesting a relevant switch of activity in this brain region induced by the scheduled activity; however, the colocalization of c-Fos in ORX-positive cells was not increased. In contrast, the suprachiasmatic nucleus and the paraventricular nucleus remained locked to the light/dark cycle, resulting in ID in the hypothalamus. Present data suggest that ID occurs already at the level of the first output projections from the SCN, relaying nuclei that transmit temporal signals to other brain areas and to the periphery.
Roberto Salgado-Delgado; Saderi Nadia; M Angeles-Castellanos; Ruud M Buijs; Carolina Escobar
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of biological rhythms     Volume:  25     ISSN:  1552-4531     ISO Abbreviation:  J. Biol. Rhythms     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-07     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8700115     Medline TA:  J Biol Rhythms     Country:  United States    
Other Details:
Languages:  eng     Pagination:  421-31     Citation Subset:  IM    
Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México DF, México.
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