Entrainment of the master circadian clock by scheduled feeding.
Am J Physiol Regul Integr Comp Physiol
; 287(3): R551-5, 2004 Sep.
Article
in En
| MEDLINE
| ID: mdl-15155280
ABSTRACT
The master circadian clock, located in the mammalian suprachiasmatic nuclei (SCN), generates and coordinates circadian rhythmicity, i.e., internal organization of physiological and behavioral rhythms that cycle with a near 24-h period. Light is the most powerful synchronizer of the SCN. Although other nonphotic cues also have the potential to influence the circadian clock, their effects can be masked by photic cues. The purpose of this study was to investigate the ability of scheduled feeding to entrain the SCN in the absence of photic cues in four lines of house mouse (Mus domesticus). Mice were initially housed in 1212-h light/dark cycle with ad libitum access to food for 6 h during the light period followed by 4-6 mo of constant dark under the same feeding schedule. Wheel running behavior suggested and circadian PER2 protein expression profiles in the SCN confirmed entrainment of the master circadian clock to the onset of food availability in 100% (49/49) of the line 2 mice in contrast to only 4% (1/24) in line 3 mice. Mice from line 1 and line 4 showed intermediate levels of entrainment, 57% (8/14) and 39% (7/18), respectively. The predictability of entrainment vs. nonentrainment in line 2 and line 3 and the novel entrainment process provide a powerful tool with which to further elucidate mechanisms involved in entrainment of the SCN by scheduled feeding.
Search on Google
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Suprachiasmatic Nucleus
/
Behavior, Animal
/
Biological Clocks
/
Circadian Rhythm
/
Feeding Behavior
Type of study:
Prognostic_studies
Limits:
Animals
Language:
En
Journal:
Am J Physiol Regul Integr Comp Physiol
Journal subject:
FISIOLOGIA
Year:
2004
Document type:
Article
Affiliation country:
United States