AJP - Endocrinology and Metabolism, Vol 267, Issue 6 E921-E926, Copyright © 1994 by American Physiological Society
Mineralocorticoid antagonist inhibits stress-induced blood pressure response after repeated daily warming
D. T. Van den Berg, W. de Jong and E. R. de Kloet
Leiden/Amsterdam Center for Drug Research, Sylvius Laboratories, Leiden University, The Netherlands.
We report here that with a direct method for measurement of cardiovascular
parameters in conscious rats, intracerebroventricular administration of the
mineralocorticoid receptor (MR) antagonist RU-28318 (100 ng) reduces the
blood pressure, heart rate, and the corticosterone response to a brief
restraint stress, provided the rats were previously subjected to a daily
30-min exposure to 32 degrees C for 2 wk. The daily exposure to warming and
restraint stress are applied identically to the training procedure required
for indirect blood pressure measurement using the tail-cuff method. The
basal arterial pressure is not affected by the MR antagonist. The effect of
the MR antagonist on the stress-induced pressor response develops with a
delay of several hours in the normotensive rats. The corticosterone
response to daily warming and stress is also attenuated by the
intracerebroventricular infusion of MR antagonist but with shorter onset
and shorter duration. The findings suggest that conditioning to daily
warming and stress imposes mineralocorticoid dependency of the pressor
response, which involves MR functioning in brain.
