AJP - Endocrinology and Metabolism, Vol 252, Issue 4 E525-E529, Copyright © 1987 by American Physiological Society
Hippocampal and renal type I receptors are differentially regulated
G. Stephenson and J. Funder
Previously, we have shown that renal mineralocorticoid receptors and
hippocampal "corticosterone-perferring" sites have identical intrinsic
steroid specificity in vitro. Others have shown that the aldosterone
binding species in kidney and hippocampus have identical trypsin
fragmentation patterns on isoelectric focusing. To further explore possible
areas of identity, we determined levels of type I receptors in hippocampus,
renal outer medulla cortex, and renal inner medulla papilla from 22 min to
16 days after adrenalectomy. Available type I sites in kidney fractions
increased postadrenalectomy to plateau levels in 22 (inner medulla papilla)
or 90 min (outer medulla cortex). In contrast, available hippocampal
receptors attained maximal levels 24-48 h postadrenalectomy. Animals, 24-h
adrenalectomized, showed no differences in steroid uptake or washout
between kidney and hippocampus, determined by in vitro tracer binding 22 or
90 min after intravenous aldosterone or corticosterone. We interpret the
marked difference in receptor levels between kidney and hippocampus
postadrenalectomy as evidence for tissue-specific differences in the
control of receptor levels by endogenous steroids.
