| Adrenergic regulation of beta-endorphin secretion from anterior pituitary in conscious rats: effects of thyroid state. | |
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MedLine Citation:
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PMID: 2948818 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In conscious, chronically cannulated, unrestrained rats, systemic administration of catecholamines increases the plasma levels of beta-endorphin-like immunoreactivity (beta Ei). In euthyroid rats, this effect is mediated by both alpha 1 and beta-adrenergic receptors; the rise in plasma beta Ei caused by isoproterenol is blocked by 1 mg/kg propranolol, and the similar effects of norepinephrine and phenylephrine are blocked by 0.1 mg/kg prazosin. Both types of responses are completely suppressed by a 4-h pretreatment of rats with 0.1 mg/kg dexamethasone, indicating the anterior pituitary origin of the beta Ei released. Prior sectioning of the pituitary stalk does not significantly reduce the response to either phenylephrine or isoproterenol, suggesting that both agents act directly on the pituitary. Hypothyroidism induced by surgical thyroidectomy does not influence the beta Ei response to isoproterenol, which remains sensitive to block by propranolol or suppression by dexamethasone. However, neither norepinephrine nor phenylephrine is able to increase plasma beta Ei in the hypothyroid animals. Both isoproterenol and phenylephrine remain fully effective in rats made hyperthyroid by daily injections of 40 micrograms/kg T3 for 4 days. We propose that in unstressed rats catecholamines increase plasma beta Ei by a direct action on the anterior pituitary via either alpha 1- or beta-adrenergic receptors, and that expression of the alpha 1-, but not the beta-adrenergic response is regulated by thyroid hormones. |
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Authors:
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E J Ishac; R Eskay; F Hirata; J Axelrod; G Kunos |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Endocrinology Volume: 120 ISSN: 0013-7227 ISO Abbreviation: Endocrinology Publication Date: 1987 Mar |
Date Detail:
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Created Date: 1987-03-26 Completed Date: 1987-03-26 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0375040 Medline TA: Endocrinology Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1073-8 Citation Subset: AIM; IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Dexamethasone / pharmacology Endorphins / blood, secretion* Isoproterenol / pharmacology* Male Norepinephrine / pharmacology* Phenylephrine / pharmacology* Pituitary Gland, Anterior / drug effects, secretion* Prazosin / pharmacology* Propranolol / pharmacology* Rats Rats, Inbred Strains Thyroid Gland / physiology* Thyroidectomy* beta-Endorphin |
| Chemical | |
Reg. No./Substance:
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0/Endorphins; 19216-56-9/Prazosin; 50-02-2/Dexamethasone; 51-41-2/Norepinephrine; 525-66-6/Propranolol; 59-42-7/Phenylephrine; 60617-12-1/beta-Endorphin; 7683-59-2/Isoproterenol |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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