Linked Life Data

185215

Source:http://linkedlifedata.com/resource/pubmed/id/185215

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
21
pubmed:dateCreated
1977-1-3
pubmed:abstractText
Cultured dog thyroid cells were used to investigate the mechanism by which previous exposure to thyrotropin (TSH) induces refractoriness to further TSH stimulation of cellular adenosine 3'-5'-monophosphate (cAMP). Refractoriness of the cAMP response to TSH could not be overcome by exposure of the cells to supramaximal stimulatory concentrations of TSH. Although an unknown factor present in human and fetal calf serum was found to inhibit the thyroid cell cAMP response to TSH, this factor could not account for refractoriness because refractoriness could be induced in the absence of serum. Induction of thyroid refractoriness did not appear to be related to cellular concentrations of cyclic AMP, because equal refractoriness was produced by TSH alone or TSH plus the phosphodiesterase inhibitor, 3-isobutyl-1-methyl xanthine. In addition, preincubation of thyroid cells in 10(-4) M cAMP did not result in subsequent refractoriness. Recovery from the refractory process required almost 24 h. Short term (15 min) stimulation with TSH did not produce thyroid cell refractoriness, and reversal of the stimulation was obtained by thorough washing of the cells. Long term TSH stimulation (16 h), however, resulted in both supramaximal cAMP response to TSH, and inclusion of TSH together with cycloheximide did not produce refractoriness. Cyclic AMP phosphodiesterase activity in thyroid cell homogenate was unaltered by TSH or dibutyryl cyclic AMP pretreatment of the cells for up to 24 h, or cycloheximide for up to 4 h. In contrast, TSH-stimulated, but not F--stimulated, adenylate cyclase activity was reduced in thyroid cell homogenates after preincubation of the cells in TSH. Refractoriness to TSH stimulation was not associated with an alteration in the binding of 125I-TSH to cultured thyroid cells. These studies suggest that the thyroid cAMP response to TSH is modulated by an inhibitory mechanism dependent upon new protein synthesis. TSH stimulation itself increases the degree of this inhibition through a mechanism not involving cAMP.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
251
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6653-61
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1976
pubmed:articleTitle
Induction of refractoriness to thyrotropin stimulation in cultured thyroid cells. Dependence on new protein synthesis.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.