Diurnal rhythmicity of human cholesterol synthesis: normal pattern
of adaptation to simulated "jet lag".
Cella, Lynn Kessler, Eve Van Cauter, Dale A. Schoeller.
Committee for Human Nutrition and Nutritional Biology and
Department of Medicine, University of Chicago, Chicago, Illinois
60637
APStracts 2:0077E, 1995.
The diurnal rhythm of cholesterol synthesis was determined by
deuterium incorporation from body water in five normolipemic men
studied during a 24-hour baseline period and on the first, second and
fourth days of a simulated 12-hour time zone shift achieved by
delaying sleep times and, starting on the second day, mealtimes.
Profiles of plasma cortisol and thyrotropin (TSH) were obtained
simultaneously. Under baseline conditions, cholesterol synthetic
rates varied from essentially zero in the morning to maximal values
around midnight. On the first shifted day, this diurnal variation was
unaltered despite sleep-wake reversal. The diurnal pattern of
cholesterol synthesis, however, was shifted 5h on second shifted day
and about 12 h on the fourth. The diurnal variation of synthetic-rate
cholesterol fractional synthesis and plasma cortisol levels were
negatively correlated on both the baseline day and the first shifted
day. A positive correlation with the TSH rhythm was found on the
first day only. During the second and fourth days, the rhythm of
cholesterol synthesis adapted faster than the rhythms of cortisol and
TSH. These findings indicate that cholesterol synthesis is not
acutely entrained by the sleep-wake cycle nor is it primarily
entrained by the circadian clock.
Received 30 November 1994; accepted in final form 6 April 1995.
APS Manuscript Number E496-4.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 April 1995.