Circadian rhythms of gastrointestinal function are regulated by both central and peripheral oscillators

Am J Physiol Gastrointest Liver Physiol. 2012 Aug 15;303(4):G461-73. doi: 10.1152/ajpgi.00369.2011. Epub 2012 Jun 21.

Abstract

Circadian clocks are responsible for daily rhythms in a wide array of processes, including gastrointestinal (GI) function. These are vital for normal digestive rhythms and overall health. Previous studies demonstrated circadian clocks within the cells of GI tissue. The present study examines the roles played by the suprachiasmatic nuclei (SCN), master circadian pacemaker for overt circadian rhythms, and the sympathetic nervous system in regulation of circadian GI rhythms in the mouse Mus musculus. Surgical ablation of the SCN abolishes circadian locomotor, feeding, and stool output rhythms when animals are presented with food ad libitum, while restricted feeding reestablishes these rhythms temporarily. In intact mice, chemical sympathectomy with 6-hydroxydopamine has no effect on feeding and locomotor rhythmicity in light-dark cycles or constant darkness but attenuates stool weight and stool number rhythms. Again, however, restricted feeding reestablishes rhythms in locomotor activity, feeding, and stool output rhythms. Ex vivo, intestinal tissue from PER2::LUC transgenic mice expresses circadian rhythms of luciferase bioluminescence. Chemical sympathectomy has little effect on these rhythms, but timed administration of the β-adrenergic agonist isoproterenol causes a phase-dependent shift in PERIOD2 expression rhythms. Collectively, the data suggest that the SCN are required to maintain feeding, locomotor, and stool output rhythms during ad libitum conditions, acting at least in part through daily activation of sympathetic activity. Even so, this input is not necessary for entrainment to timed feeding, which may be the province of oscillators within the intestines themselves or other components of the GI system.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic beta-Agonists / pharmacology
  • Animals
  • Biological Clocks* / drug effects
  • Biological Clocks* / genetics
  • Blotting, Western
  • Circadian Rhythm* / drug effects
  • Circadian Rhythm* / genetics
  • Defecation
  • Denervation / methods
  • Eating
  • Feeding Behavior
  • Gastrointestinal Tract / innervation*
  • Immunohistochemistry
  • Isoproterenol / pharmacology
  • Luciferases / genetics
  • Luciferases / metabolism
  • Male
  • Mice
  • Mice, 129 Strain
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Motor Activity
  • Oxidopamine / pharmacology
  • Period Circadian Proteins / genetics
  • Period Circadian Proteins / metabolism
  • Photoperiod
  • Suprachiasmatic Nucleus / physiology*
  • Suprachiasmatic Nucleus / surgery
  • Sympathectomy, Chemical
  • Sympathetic Nervous System / drug effects
  • Sympathetic Nervous System / physiology*
  • Sympatholytics / pharmacology
  • Time Factors

Substances

  • Adrenergic beta-Agonists
  • Period Circadian Proteins
  • Sympatholytics
  • Oxidopamine
  • Luciferases
  • Isoproterenol