In:
American Journal of Physiology-Endocrinology and Metabolism, American Physiological Society, Vol. 274, No. 2 ( 1998-02-01), p. E238-E245
Abstract:
The acute effects of thyroid hormones on glucocorticoid secretion were studied. Venous blood samples were collected from male rats after they received intravenous 3,5,3′-triiodothyronine (T 3 ) or thyroxine (T 4 ). Zona fasciculata-reticularis (ZFR) cells were treated with adrenocorticotropic hormone (ACTH), T 3 , T 4 , ACTH plus T 3 , or ACTH plus T 4 at 37°C for 2 h. Corticosterone concentrations in plasma and cell media, and also adenosine 3′,5′-cyclic monophosphate (cAMP) production in ZFR cells in the presence of 3-isobutyl-1-methylxanthine, were determined. The effects of thyroid hormones on the activities of steroidogenic enzymes of ZFR cells were measured by the amounts of intermediate steroidal products separated by thin-layer chromatography. Administration of T 3 and T 4 suppressed the basal and the ACTH-stimulated levels of plasma corticosterone. In ZFR cells, both thyroid hormones inhibited ACTH-stimulated corticosterone secretion, but the basal corticosterone was inhibited only with T 3 〉 10 −10 M or T 4 〉 10 −8 M. Likewise, T 3 or T 4 at 10 −7 M inhibited the basal- and ACTH-stimulated levels of intracellular cAMP. Physiological doses of T 3 and T 4 decreased the activities of 3β-hydroxysteroid dehydrogenase, 21-hydroxylase, and 11β-hydroxylase. These results suggest that thyroid hormones counteract ACTH in adrenal steroidogenesis through their inhibition of cAMP production in ZFR cells.
Type of Medium:
Online Resource
ISSN:
0193-1849
,
1522-1555
DOI:
10.1152/ajpendo.1998.274.2.E238
Language:
English
Publisher:
American Physiological Society
Publication Date:
1998
detail.hit.zdb_id:
1477331-4
detail.hit.zdb_id:
603841-4
SSG:
12
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