Corticosteroid receptor mrna expression is unaffected by
corticosteroids in the rat kidney, heart, and colon.
Escoubet, B., C. Coureau, M. Blot-Chabaud, J. P. Bonvalet, and N.
Farman.
INSERM U246 AND 426, Institut Fdratif de Recherches, ECellules
EpithlialesEE, Facult de Mdecine X. Bichat, BP 416, 75870 PARIS Cdex
18, FRANCE
APStracts 2:0403C, 1995.
Hormones can regulate the expression of their own receptor. We have
examined whether adrenalectomy (Adx) and hormone replacement by
physiological doses of aldosterone or dexamethasone could modulate
the expression of gluco- (GR) or mineralocorticoid (MR) receptor at
the mRNA level, in the rat kidney, distal colon, and heart. Adult
rats were adrenalectomized, and received or not infusion of
aldosterone (5 [mu]g/100 g/day) or dexamethasone (10 [mu]g/100
g/day). No significant change in steady state levels of both MR and
GR mRNAs was detectable using RNAse protection assay (RPA), either
after Adx or hormone replacement. Since the kidney is heterogeneous
with regards to MR expression, RPA was adapted for measurements on
microdissected nephron segments. GR mRNA is expressed at comparable
levels all along the nephron, while MR mRNA is restricted to the
distal nephron. No effect of Adx on GR and MR mRNA levels was
detected in in any nephron segment, either aldosterone-sensitive or
insensitive. In situ hybridization confirmed the absence of
corticosteroid-dependent modulation of MR mRNA in any kidney cell
type. We conclude that variations of corticosteroid status does not
affect MR and GR mRNA steady state levels in heart, colon, and
kidney, and thus do not participate to the functional adaptations
which are known to depend on hormonal status.
Received 12 September 1995; accepted in final form 3 November
1995.
APS Manuscript Number C221-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95