Linked Life Data

6723584

Source:http://linkedlifedata.com/resource/pubmed/id/6723584

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1984-7-13
pubmed:abstractText
Studies were designed to determine whether an autoregulation system exists for TSH in the rabbit. For this purpose, a species-specific RIA for rabbit TSH that does not cross-react with human (h) TSH was developed. Hypothyroid animals were studied at varying time periods up to 3 months after either surgical thyroidectomy or propylthiouracil (PTU) treatment. Highly purified hTSH was injected iv at doses of 0 (saline control), 0.1, 0.3, 1,3, and 10 micrograms into unanesthetized rabbits bearing chronically implanted Silastic catheters. Blood samples were obtained at -30, 0, 10, 20, 30, 60, 120, 180, 240, and 300 min and 24 h. Doses between 0.3 and 10 micrograms hTSH produced a prompt fall (10 min) in rabbit TSH in hypothyroid rabbits studied 8-21 days after thyroidectomy. The minimum dose of hTSH that significantly suppressed rabbit TSH was 0.3 micrograms. This dose produced a peak value of hTSH in rabbit serum of 1.3 +/- 0.1 (+/- SEM) ng/ml 10 min after injection, which translates into a bioassay potency of 2.0 microU/ml (close to the physiological level in humans). A dose-response relationship existed between the hTSH dose injected and the duration and magnitude of suppression of rabbit TSH. This response to TSH was specific; 10 micrograms hTSH produced no change in endogenous rabbit serum LH and, conversely, 10 IU hLH produced no change in rabbit serum TSH. In contrast to these striking effects in acute hypothyroid animals, hTSH produced no detectable suppression of rabbit TSH in animals that were hypothyroid for 2-3 months. The sensitivity of the autoregulatory system to the suppressive effects of exogenous hTSH decreased with increasing duration of hypothyroidism; a time-response relationship existed. We conclude that: 1) a sensitive and specific autoregulatory control system for TSH exists in the rabbit; and 2) as the duration of hypothyroidism increases, the sensitivity of the autoregulatory system to the suppressive effects of endogenous TSH changes.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0013-7227
pubmed:author
pubmed:issnType
Print
pubmed:volume
114
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2301-5
pubmed:dateRevised
2004-11-17
pubmed:meshHeading
pubmed:year
1984
pubmed:articleTitle
Autoregulatory control of thyrotropin in rabbits.
pubmed:publicationType
Journal Article