Circadian organization of thirteen liver and six brain enzymes of the mouse.
North-C; Feuers-RJ; Scheving-LE; Pauly-JE; Tsai-TH; Casciano-DA
Am J Anat 1981 Nov; 162(3):183-199
Studies were conducted in mice to to determine the effects of circadian organization on 13 liver and six brain enzymes. Male CD2F1-mice were standardized either to 12 hours of light alternating with 12 hours of darkness or to the reversed dark/light cycle for 2 weeks. Mice in one group were 7 weeks old, while those in another group were 12 weeks old. Mice were killed at 3 hour intervals over a period of 2 days; brains and livers were removed and analyzed for enzymes. All 19 enzymes demonstrated a prominent circadian rhythm in at least one experiment. A statistically significant fit was noted by each rhythmic variable to a 24 hour cosine curve by the method of least squares. Liver enzymes showed their peak activities at the beginning of the dark cycle and initiation of the animal's activity. Brain enzymes peaked in activity at the beginning of the rest span and near the beginning of the light cycle. The beginning of the dietary intake process in the rodent normally occurs at the onset of darkness, and this may account for the clustering of the acrophases in enzyme activity at the beginning of the dark span. The phasing of each of the rhythms could be reversed within a 2 week period after reversing the environmental light/dark cycle by 180 degrees. The authors suggest this is the first study to simultaneously consider, from a chronobiological viewpoint, more than one or a few enzymes in the same animals in a single experiment.
NIOSH-Publication; NIOSH-Grant; Neurotoxic-effects; Laboratory-animals; Biological-rhythms; Circadian-rhythms; Liver-enzymes; Central-nervous-system
Anatomy University of Arkansas 4301 West Markham Little Rock, Ark 72201
Neurotoxic Disorders; Neurotoxic-effects
American Journal of Anatomy
University of Arkansas Med Scis Ltl Rock, Little Rock, Arkansas