Involvement of type i corticosteroid receptor in the effects of
ovariectomy on energy balance.
Dagnault, Anne, Yves Deshaies, and Denis Richard.
D[acute]epartement de Physiologie, Facult[acute]e de
M[acute]edecine, Universit[acute]e Laval, Qu[acute]ebec (Qu[acute]e),
G1K 7P4, CANADA
APStracts 2:0227R, 1995.
The effects of the glucocorticoid receptor (GR) antagonist, RU38486
(RU486), and the mineralocorticoid receptor (MR) antagonist, RU28318,
on energy balance were investigated in a 2 [surgery: ovariectomy
(OVX) and sham-operation] x 3 [CORTICOSTEROID antagonist: placebo,
RU28318, RU486] experimental design. Rats were treated for 28 days.
Food intake and body weight were monitored throughout the treatment
period. At the end of the treatment, rats were killed and their
carcass was analysed for energy and nitrogen contents. Energy content
was determined by adiabatic bomb calorimetry whereas nitrogen was
determined in 250-300 mg samples of dehydrated samples using the
Kjeldahl procedure. The energy as protein was subtracted from total
carcass energy in order to determine energy as fat. The gains in
energy, fat and protein were calculated by subtracting the values
obtained at the end of the treatment period from initial values
estimated from the body weights mesured at the beginning of the
experiment. A significant interaction effect of surgery and
CORTICOSTEROID antagonist was observed on body energy gain, energetic
efficiency and fat gain. Whereas body energy gain, energetic
efficiency and fat gain were larger in ovariectomized (ovx) rats than
in sham-operated animals treated with either placebo or RU486, they
were comparable in ovx and sham-operated rats treated with RU28318.
Surgery, but not CORTICOSTEROID antagonist, had a significant effect
on digestible energy intake, energy expenditure and protein gain. All
these variables were higher in ovx rats than in sham-operated
animals. Surgery also affected corticosterone levels and adrenal
weight. Both these variables were lower in ovx rats than in sham
-operated animals. By demonstrating the ability of RU28318 to
attenuate the effects of OVX on energy balance, the present study
provides evidence that MR occupation by corticosteroids facilitates
the OVX-induced changes in energy balance.
Received 12 December 1994; accepted in final form 18 July 1995.
APS Manuscript Number R701-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 August 1995.