Effects of the morning rise in cortisol concentration on regulation
of lipolysis in subcutaneous adipose tissue.
Samra, J. S., M. L. Clark, S. M. Humphreys, I. A. Macdonald, D. R.
Matthews, and K. N. Frayn.
Oxford Lipid Metabolism Group, Nuffield Department of Clinical
Medicine, Radcliffe Infirmary, Oxford OX2 6HE, UK, Department of
Physiology and Pharmacology, Medical School, Queen's Medical Centre,
Nottingham NG7 2UH, UK
APStracts 3:0150E, 1996.
Cortisol has a well defined circadian rhythm. The aim of the study was
to examine the effect of the morning rise in cortisol concentration
on lipolysis in adipose tissue. Ten healthy subjects were studied on
two occasions, and six of these were studied on three occasions.
During the first two occasions either a control or cortisol
suppression study was performed by using metyrapone, and on the third
occasion exogenous cortisol replacement was given in addition to
metyrapone. Lipolysis in the subcutaneous adipose tissue of the
anterior abdominal wall was studied by measurement of arterio-venous
differences. Reduction in the early morning rise in cortisol led to
significantly decreased veno-arterialized differences for non
esterified fatty acids (P < 0.05) and glycerol (P < 0.01),
attributable in part to decreased hormone-sensitive lipase (HSL: EC
3.1.1.3) action (P < 0.05) in adipose tissue. At the same time
the arterialized plasma triacylglycerol concentration increased (P
< 0.005) with a significant reduction in the adipose lipoprotein
lipase (LPL: EC 3.1.1.34) rate of action (P < 0.05). In the
replacement study values were identical to those of the control
study, showing that metyrapone had no non-specific effects on
lipolysis. We conclude that the morning rise in plasma cortisol
concentration plays an important role in the regulation of lipolysis
in adipose tissue in normal healthy adults.
Received 25 April 1996; accepted in final form 25 July 1996.
APS Manuscript Number E205-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 21 August 1996