Thyrotropin-releasing hormone inhibits glucocorticoid secretion of rat adrenal cortex: in vivo and in vitro studies.
The bolus iv administration of TRH dose-dependently decreased ACTH-enhanced plasma corticosterone (B) concentration in rats, without affecting the basal one. The effects of TRH on steroid secretion of dispersed rat inner adrenocortical cells were investigated by HPLC. TRH significantly decreased both basal and ACTH-stimulated post-11-deoxycorticosterone (DOC) secretion (i.e. 18-hydroxy-DOC and B) and concomitantly raised DOC and progesterone release, so that the total postpregnenolone yield of our preparations was unaffected. TRH did not alter either basal or ACTH-stimulated pregnenolone production by isolated rat adrenocortical cells. It was concluded that TRH is an inhibitor of glucocorticoid secretion in rats, which electively impairs the late steps of B synthesis (i.e. 11- and 18-hydroxylation) without affecting the earlier steps, including the rate-limiting one of this process.
Department of Anatomy, University of Padua, Italy.
G
G
Neri
L K
LK
Malendowicz
P
P
Andreis
G G
GG
Nussdorfer
D015070:18-Hydroxydesoxycorticosterone / Q000378:metabolism; D000302:Adrenal Cortex / Q000187:drug effects / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003345:Corticosterone / Q000378:metabolism; D003900:Desoxycorticosterone / Q000378:metabolism; D005938:Glucocorticoids / Q000378:metabolism*; D008297:Male; D011284:Pregnenolone / Q000096:biosynthesis; D011374:Progesterone / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D015070:18-Hydroxydesoxycorticosterone; D005938:Glucocorticoids; D003900:Desoxycorticosterone; D011374:Progesterone; D013973:Thyrotropin-Releasing Hormone; D011284:Pregnenolone; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone