Triiodothyronine attenuates estradiol-induced increases in dopamine D-2 receptor number in rat anterior pituitary
Language English Country Netherlands Media print
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
8705298
DOI
10.1016/0006-8993(95)01524-8
PII: 0006-8993(95)01524-8
Knihovny.cz E-resources
- MeSH
- Pituitary Gland, Anterior drug effects metabolism MeSH
- Cyclic AMP metabolism MeSH
- Estrogen Antagonists pharmacology MeSH
- Rats MeSH
- Rats, Wistar MeSH
- Prolactin metabolism MeSH
- Receptors, Dopamine D2 drug effects metabolism MeSH
- Thyrotropin metabolism MeSH
- Thyroxine metabolism MeSH
- Triiodothyronine pharmacology MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Cyclic AMP MeSH
- Estrogen Antagonists MeSH
- Prolactin MeSH
- Receptors, Dopamine D2 MeSH
- Thyrotropin MeSH
- Thyroxine MeSH
- Triiodothyronine MeSH
Estrogens promote adenohypophyseal enlargement and tumor transformation, and thyroid hormones antagonize these effects. Hormone-induced pituitary enlargement may be mediated by alterations in pituitary dopaminergic function. The present study examined the effects of chronic (20 days) administration of estradiol benzoate (EB), triiodothyronine (T3), or EB and T3 (T3 + EB) on dopamine (D-2) receptors in rat anterior pituitary. D-2 receptor number increased after EB without altered receptor affinity. T3 alone did not affect D-2 receptor number in the anterior pituitary but significantly attenuated the effect of EB. T3 administration also inhibited EB-induced anterior pituitary hyperplasia. D-2 receptor upregulation by EB more likely could reflect a compensatory response to decreased receptor occupation. The present results suggest that D-2 receptors could play an important role in estrogen-induced adenohypophyseal tumor formation and hyperprolactinemia and that thyroid hormones may inhibit estrogen-induced pituitary tumor development via adenohypophyseal D-2 receptors.
References provided by Crossref.org
In vivo antiestrogenic activity of mifepristone in the rat
