Effects of adrenalectomy and glucocorticoid receptor antagonist, RU38486, on pituitary growth hormone-releasing hormone receptor gene expression in rats.
We examined the effects of adrenalectomy and a glucocorticoid receptor antagonist, RU38486, on pituitary GH-releasing hormone (GRH) receptor gene expression in rats. GRH receptor mRNA levels were significantly decreased in adrenalectomized rats and replacement of dexamethasone reversed the decrease to normal. GH secretion was inhibited by adrenalectomy, whereas dexamethasone replacement failed to restore the impaired GH secretion. A high dose of RU38486 had an agonistic effect on GRH receptor mRNA levels. These results suggest that endogenous glucocorticoid is necessary for normal expression of pituitary GRH receptor mRNA in rats.
First Department of Internal Medicine, Kagawa Medical University, Japan.
T
T
Ohyama
M
M
Sato
H
H
Ohye
K
K
Murao
M
M
Niimi
J
J
Takahara
D000315:Adrenalectomy; D000818:Animals; D003345:Corticosterone / Q000097:blood; D005786:Gene Expression Regulation / Q000187:drug effects*; D013006:Growth Hormone / Q000097:blood; D008297:Male; D015735:Mifepristone / Q000494:pharmacology*; D010902:Pituitary Gland / Q000737:chemistry / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors*; D018013:Receptors, Neuropeptide / Q000235:genetics*; D018017:Receptors, Pituitary Hormone-Regulating Hormone / Q000235:genetics*
D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D015735:Mifepristone; D013006:Growth Hormone; C048250:somatotropin releasing hormone receptor; D003345:Corticosterone