AJP - Endocrinology and Metabolism, Vol 259, Issue 3 E405-E412, Copyright © 1990 by American Physiological Society
Adrenal steroid receptor binding in spleen and thymus after stress or dexamethasone
A. H. Miller, R. L. Spencer, M. Stein and B. S. McEwen
Department of Psychiatry, Mount Sinai School of Medicine, New York, New York 10029.
Type I and II adrenal steroid receptor binding was measured in spleen and
thymus of adrenalectomized (ADX) rats and intact rats at basal levels of
corticosterone after 1 h of restraint stress or after exogenous
administration of dexamethasone (DEX). Concurrent receptor determinations
were made in the hippocampus and pituitary. Receptor binding measures in
immune tissues and pituitary were less responsive to varying levels of
endogenous hormones than binding measures in hippocampus. Compared with ADX
rats, type I binding in spleen and pituitary of intact rats at basal levels
of corticosterone was unchanged, whereas type I binding in the hippocampus
was significantly decreased. Furthermore, despite peak levels of
corticosterone, type II binding in spleen, thymus, and pituitary of
stressed rats was also unchanged, whereas type II binding in the
hippocampus of stressed animals was significantly lower. In contrast, DEX,
a well-known immunosuppressant, reduced type II binding in immune tissues
more than in the hippocampus. Because a decrease in receptor binding
measured in vitro may reflect receptor activation in vivo, these results
suggest that there may be considerable heterogeneity in the degree of
activation of adrenal steroid receptor subtypes in immune, pituitary, and
hippocampal tissue by endogenous and exogenous glucocorticoids.
