Interaction of corticosterone and gonadal steroids on lipid
deposition in the female rat.
Deshaies, Yves, Anne Dagnault, Jos[umlaut]ae Lalonde, and Denis
Richard.
Department of Physiology, School of Medicine, Laval University,
Qu[umlaut]abec, Qc, Canada G1K 7P4
APStracts 4:0099E, 1997.
The present study was designed to evaluate the interaction of
corticosterone (CORT) and female gonadal steroids on energy balance
and lipid metabolism. To this end, a 2x4 factorial experiment was
carried out in which two cohorts of rats differing in their ovary
status [OV status: intact (INT) and ovariectomy (OVX)] were each
divided into four groups defined by their CORT status [CORT status:
non-adrenalectomized (non-ADX), ADX without CORT replacement (placebo
subcutaneous pellet), ADX with low-dose CORT replacement, and ADX
with high-dose CORT replacement]. After three weeks of treatment and
a 12-hr fast, rats were killed and their carcasses analyzed for their
energy (lipid and protein) content. In addition, indices of
endogenous triglyceride (TRIG) production (liver TRIG content),
transport into plasma (triglyceridemia), and incorporation into fat
stores (lipoprotein lipase [LPL] activity in adipose tissue [AT])
were assessed. OV and CORT status interacted upon body weight gain,
total energy and fat gains. The interactions arose from the fact that
the twofold increase in these variables brought by OVX was abolished
by ADX, and restored by CORT replacement. Although in ADX groups
there was a dose-related restoration of total energy and fat gain by
CORT replacement in both INT and OVX cohorts, the impact thereupon of
OVX observed in the non-ADX group reappeared only in ADX animals
receiving the high dose of CORT. Protein gain was increased by OVX
solely in non-ADX rats, whereas the high dose of CORT prevented any
net protein gain, independently of the OV status. Consistent with
treatment effects on total body fat gain, OVX resulted in an increase
in liver TRIG content, AT weight, AT LPL activity, and plasma
insulin. All these effects of OVX were abolished by ADX and restored
by the high dose of CORT. Plasma TRIG were unaffected by OV status
but highly responsive to CORT status. All treatment effects were
highly correlated with cumulative food intake. This study shows that
the presence of CORT is required for OVX to exert its action upon
global energy balance and the concomitant, closely integrated
adaptations of lipid metabolism.
Received 1 January 1997; accepted in final form 15 April 1997.
APS Manuscript Number E39-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 13 May 1997