Melatonin and s-20098 advance circadian phase and nocturnal
regulation of core body temperature.
Kr[umlaut]auchi, Kurt, Christian Cajochen, David M[diaeresis]ori,
Peter Graw, and Anna Wirz-Justice.
Psychiatric University Clinic, Wilhelm Klein-Strasse 27, CH-4025
BASEL, Switzerland
APStracts 3:0394R, 1996.
The phase-shifting capacity and thermoregulatory effects of a single
p.o. administration at 18h of melatonin (5 mg, MEL) or S-20098, a
melatonin agonist [5 mg (S5) or 100 mg (S100)] was investigated in
eight healthy young men in a double-blind placebo crossover design.
The unmasking conditions of a shortened constant routine protocol
(mini-CR) were used to collect evening phase markers of physiological
parameters. In comparison to placebo, all three drug administrations
induced an earlier dim light melatonin onset (DLMO), an earlier
increase in distal skin temperature, and an earlier decrease in core
body temperature (CBT), heart rate and proximal skin temperature.
This indicates that administration at 18h of both melatonin and S
-20098 (more pronounced with 100mg than 5mg), induced an earlier
regulation of the endogenous circadian nocturnal decline in CBT. On
the post-treatment day a second mini-CR revealed persistent
significant phase advanced circadian rhythms as estimated by DLMO, as
well as by the mid-range crossing time of CBT and heart rate decline.
There were no significant differences between the two doses of S
-20098. The data suggest that in addition to immediate
thermoregulatory changes, a phase advance of the circadian system had
occurred, and that the phase advance could still be measured on the
post-treatment day.
Received 17 November 1995; accepted in final form 16 October
1996.
APS Manuscript Number R722-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996