Corticosterone inhibition of osmotically-stimulated vasopressin
from hypothalamic-neurohypophysial explants.
Papanek, Paula E., Celia D. Sladek, and Hershel Raff.
Program in Physical Therapy, Marquette University, Milwaukee, WI
53201, Department of Physiology and Biophysics, Chicago Medical
School, N. Chicago, IL 60064, Departments of Physiology &
Medicine, The Medical College of Wisconsin 53226, and Endocrine
Research Laboratory, St. Luke's Medical Center, Milwaukee, WI
53215
APStracts 3:0283R, 1996.
Glucocorticoids inhibit and glucocorticoid deficiency increases
vasopressin (AVP) release in vivo. To determine whether the effect of
glucocorticoids is hypothalamic and mediated via a glucocorticoid
receptor, explants of the hypothalamic-neurohypophysial system were
used to measure AVP release during agonist and antagonist exposure.
Explants from adult rats, which contained AVP neurons of the
supraoptic nucleus with axonal projections terminating in the neural
lobe but excluded the paraventricular nucleus, were perifused with an
osmotic stimulus (increase of 5 mOsm/hr over 6 hr) in the absence or
presence of corticosterone (100 [mu]g/dl) or with corticosterone (100
[mu]g/dl) in the absence or presence of the glucocorticoid antagonist
RU 486 (10 [mu]M). AVP release was not increased during osmotic
stimulation in the presence of CORT and was 20-30% lower than
osmotically stimulated release observed in the absence of CORT. RU
486 reversed the inhibitory effect of corticosterone on AVP release.
No changes in AVP mRNA content were detected. These results suggest
that corticosterone inhibits osmotically stimulated AVP release by a
direct effect within the hypothalamus and/or neurohypophysis. This
effect is mediated by the glucocorticoid receptor through either
genomic or non-genomic mechanisms.
Received 26 January 1996; accepted in final form 28 June 1996.
APS Manuscript Number R53-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996