Journal of Neuroscience, Vol 9, 1134-1140, Copyright © 1989 by Society for Neuroscience
Receptor specificity of a glucocorticoid- and stress-induced hippocampal protein
LK Schlatter and LA Dokas
Department of Biochemistry, Medical College of Ohio, Toledo 43699.
Following treatment of rats with a subcutaneous injection of 5 mg of
corticosterone, hippocampal slices in vitro show increased labeling from
35S-methionine of a protein with an apparent molecular weight (Mr) of
35,000. Increased protein labeling is seen in response to corticosterone,
dexamethasone, and aldosterone, steroids that associate with glucocorticoid
receptors. Little or no response occurs after administration of
progesterone or estradiol. Because the injected dose of steroids is high
and responses to an injection of this magnitude may be pharmacological,
several experiments have been done to determine whether stimuli that
increase endogenous levels of corticosterone have the same effect on
labeling of the 35,000 Mr protein. One hour after various stresses
(immobilization, cold, ether, and sham-injection), when plasma levels of
corticosterone are elevated, labeling of the 35,000 Mr protein is
increased. Injection of ACTH also stimulates the synthesis of this protein
in intact animals in a manner analogous to that seen with corticosterone
injections. In addition, a dose-response curve for corticosterone with
adrenalectomized rats shows that synthesis of the protein is maximally
increased when the injected dosage causes serum levels of corticosterone to
increase to the levels seen during stress. The increase in labeling of the
35,000 Mr protein in adrenalectomized animals is only half as great as that
observed in intact animals. Injections of the type II glucocorticoid (GR)
receptor agonist, RU 28362, into adrenalectomized rats differentially
stimulates the synthesis of the 35,000 Mr protein compared with the
mineralocorticoid aldosterone, which has a higher affinity for the type I
(CR) receptor.(ABSTRACT TRUNCATED AT 250 WORDS)