Document Detail


Suppression of thyrotropin by 3,5-dimethyl-3'-isopropyl-L-thyronine in euthyroid and hypothyroid rats.
MedLine Citation:
PMID:  7408758     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effect of 3,5-dimethyl-3'-isopropyl-L-thyronine (DIMIT) a nonhalogenated thyroid hormone analog, on plasma and pituitary TSH levels was studied in euthyroid and 5-day-thyroidectomized (T-5d) rats. The minimal dose of DIMIT which suppressed basal plasma TSH for a 24-h period was 5.3 micrograms/100 g BW in the euthyroid rats and 5.2 micrograms/100 g BW in the T-5d group. The equipotent doses of T3 were 1.0 and 1.5 micrograms/100 g BW, respectively. Thus, the apparent DIMIT to T3 molar ratio ranged from 6.6 in the hypothyroid to 10 in the euthyroid group. The suppression of TRH-induced TSH release in the euthyroid rats required a high dose of DIMIT (9.2 micrograms/100 g BW), resulting in a DIMIT to T3 molar ratio of 17. Time-course studies comparing the effects of equipotent doses of DIMIT and T3 on TSH release rates in euthyroid and T-5d rats have shown a maximal suppression by 3--24 h after the administration of both T3 and DIMIT. However, the recovery from the effect was slower after T3. TSH synthesis in the T-5d group was similarly suppressed by DIMIT and T3. DIMIT has significant thyromimetic activity in euthyroid and hypothyroid rats, as evidenced by the suppresion of TSH synthesis and release.
Authors:
S Melmed; O Spira; A Gordon; J Gross; E C Jorgensen; J M Hershman
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Endocrinology     Volume:  107     ISSN:  0013-7227     ISO Abbreviation:  Endocrinology     Publication Date:  1980 Oct 
Date Detail:
Created Date:  1980-11-24     Completed Date:  1980-11-24     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0375040     Medline TA:  Endocrinology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1050-4     Citation Subset:  AIM; IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Dose-Response Relationship, Drug
Hypothyroidism / metabolism*
Male
Pituitary Gland / drug effects,  metabolism*
Rats
Thyroid Gland / physiology*
Thyronines / pharmacology*
Thyrotropin / metabolism*
Thyroxine / blood
Triiodothyronine / blood
Grant Support
ID/Acronym/Agency:
HD-7181/HD/NICHD NIH HHS
Chemical
Reg. No./Substance:
0/Thyronines; 26384-44-1/3,5-dimethyl-3'-isopropyl-L-thyronine; 6893-02-3/Triiodothyronine; 7488-70-2/Thyroxine; 9002-71-5/Thyrotropin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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