Document Detail


A thyrotropin-like molecule from the pituitary of an Indian freshwater murrel: comparison of its biological activity with other thyrotropins.
MedLine Citation:
PMID:  11790339     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Murrel pituitary thyrotropin-like molecule (mTSH) was purified to homogeneity with the help of a convenient and sensitive in vitro assay system where addition of this material to the thyroid follicle incubation stimulated thyroxine (T(4)) secretion into the medium. Pituitary extract of a freshwater murrel, Channa punctatus, was solvent extracted to obtain glycoprotein enriched fraction. This was subjected to Sephadex G-100 gel filtration and eluate of void volume (peak I) showed strong TSH activity (as reflected from T(4) secretion) which was further purified by using concanavalin A-Sepharose, FPLC Mono Q and immunoaffinity chromatography. Purified mTSH gave a single band in PAGE, and SDS PAGE revealed two dissimilar subunits, alpha and beta. Addition of increasing concentrations of mTSH, Indian carp TSH (cTSH) and bovine TSH (bTSH) to in vitro murrel thyroid follicle incubations caused a linear increase in thyroxine (T(4)) release into the medium, effect was highest with mTSH and lowest with bTSH. However, in in vivo experiments, injections of increasing doses of mTSH to murrel elevated plasma T(4) level in a linear manner while bTSH gave a biphasic response. Addition of mTSH and bTSH to rat or goat thyroid epithelial cell incubations equally stimulated T(4) release into the medium, while cTSH had significantly less effect. Binding affinity (K(a)) and receptor occupancy (B(max)) of mTSH to murrel thyroid follicular membrane preparation was considerably higher in comparison to cTSH or bTSH whereas both mTSH and bTSH had nearly similar K(a) and B(max) with rat thyroid epithelial cell membrane preparation. Findings indicate that mTSH is a more potent TSH as compared to carp and bovine TSH in murrel and has equipotent biological activity as bTSH on rat and goat thyroid.
Authors:
P Roy; A Chatterjee; P P Banerjee; S Bhattacharya
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Comparative biochemistry and physiology. Toxicology & pharmacology : CBP     Volume:  125     ISSN:  1532-0456     ISO Abbreviation:  Comp. Biochem. Physiol. C Toxicol. Pharmacol.     Publication Date:  2000 Feb 
Date Detail:
Created Date:  2002-01-15     Completed Date:  2002-02-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  100959500     Medline TA:  Comp Biochem Physiol C Toxicol Pharmacol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  165-77     Citation Subset:  IM    
Affiliation:
Department of Physiology, University of Turku, Kiinamyllynkatu 10, FIN 20520, Turku, Finland.
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MeSH Terms
Descriptor/Qualifier:
Animals
Binding Sites
Chromatography / methods
Goats
Perciformes / physiology*
Pituitary Gland / physiology*
Rats
Receptors, Thyrotropin / physiology
Thyrotropin / isolation & purification*,  pharmacology*
Thyroxine / pharmacology
Chemical
Reg. No./Substance:
0/Receptors, Thyrotropin; 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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