Effects of the scheduling of meal-feeding at different phases of the circadian system in rats.
This study was designed to determine whether or not a number of diverse rhythmic variables in the rat could be synchronized to meal timing. This was tested by restricting the availability of food; once during each 24-hour period an unrestricted quantity of food was made available for a 4-hour period to four different groups at different phases of the light-dark cycle, and the rhythms of the variables studied in the different groups were compared. Liver glycogen and serum glucose did synchronize to or were strongly influenced by feeding schedules; corticosterone and the several enzymes measured seemed to reflect an interaction of both the restricted feeding schedule and the light-dark cycle. The mitotic index in the corneal epithelium in all groups remained remarkably synchronized to the light-dark cycle and was altered only minimally by restricted meal timing. All groups on restricted feeding schedules gained less weight than the group fed ad libitum and maintained on a light-dark cycle. These studies caution against assuming that all body functions react in the same manner to different synchronizers; and they emphasize that one must not generalize about the synchronizing effect of meal-timing or even the light-dark cycle.
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism; D001835:Body Weight; D002940:Circadian Rhythm; D003345:Corticosterone / Q000097:blood; D004848:Epithelium / Q000378:metabolism; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D006884:Hydroxybutyrate Dehydrogenase / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008029:Lighting; D008099:Liver / Q000378:metabolism; D008112:Liver Glycogen / Q000378:metabolism; D010710:Phosphates / Q000097:blood; D051381:Rats
D001786:Blood Glucose; D001798:Blood Proteins; D008112:Liver Glycogen; D010710:Phosphates; D007770:L-Lactate Dehydrogenase; D006884:Hydroxybutyrate Dehydrogenase; D003345:Corticosterone