In:
Acta Endocrinologica, Oxford University Press (OUP), Vol. 124, No. 5 ( 1991-05), p. 463-469
Abstract:
The effect of the ionophore A23187 on a. the release of thyroid hormone from perifused mouse thyroid glands and b. the morphological changes in follicular epithelial cells was evaluated. A23187 at a concentration of 5 μmol/l significantly inhibited both the TSH- and the forskolin-stimulated release of T 3 and T 4 . In the presence of 3-isobutyl-1-methylxanthine or (4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone) RO 20-1724, A23187 did not affect the forskolin-stimulated release of cAMP, but did inhibit the release of T 3 and T 4 stimulated by forskolin. Light and electron microscopic evaluation of the follicular epithelial cells of mouse thyroid tissues following 1-h stimulation with forskolin showed numerous pseudopods engulfing luminal colloid of various size and the presence of reabsorbed colloid droplets in the apical cytoplasm. Quantitative electron microscopic analysis revealed that the addition of the ionophore A23187 reduced the number of reabsorbed colloid droplets to one eighth in follicular epithelial cells. These observations suggest that the increase in intracellular Ca 2+ induced by the ionophore A23187 inhibits the TSH-stimulated thyroid hormone release independently of the cAMP level, and that the suppression of thyroid hormone release may be due to an inhibition of colloid reabsorption.
Type of Medium:
Online Resource
ISSN:
0804-4643
,
1479-683X
DOI:
10.1530/acta.0.1240463
Language:
Unknown
Publisher:
Oxford University Press (OUP)
Publication Date:
1991
detail.hit.zdb_id:
1485160-X
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