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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1977-6-30
pubmed:abstractText
The effect of estradiol and thyroid hormone treatment on pituitary TRH binding and TSH and PRL responses to the neurohormone was studied. A significant increase in the number of pituitary TRH binding sites was observed between 2 and 4 days after daily administration of estradiol benzoate with a plateau at 300% of control being reached at 7 days. Plasma PRL levels showed a similar early pattern of response. In animals rendered hypothyroid by a 2-month treatment with propylthiouracil or 1 month after surgical thyroidectomy, the level of pituitary TRH receptors was increased approximately 2-fold, this elevation being completely reversed by treatment with thyroid hormone. Estradiol-17beta administered with L-thyroxine partially reversed the inhibitory effect of thyroid hormone on TRH receptor levels in hypothyroid animals. The antagonism between estrogens and thyroid hormone is also apparent on the TSH response to TRH since estrogen administration can reverse the marked inhibition by thyroxine of the TSH response to TRH either partially or completely in intact and hypothyroid animals, respectively. The PRL response to TRH is 55 and 40% inhibited in hypothyroid and intact rats, respectively, by thyroid hormone when combined with estrogen treatment. The present data clearly show that estrogens and thyroid hormones can affect TSH and PRL secretion, the effect of estrogens being predominantly on PRL secretion while thyroid hormone affects mainly TSH. The close correlation observed between the level of TRH receptors and PRL and TSH responses to TRH suggests that estrogens and, to a lesser extent, thyroid hormones, exert their action by modulation of the level of receptors for the neurohormone in both thyrotrophs and mammotrophs.
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
100
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1496-504
pubmed:dateRevised
2005-11-17
pubmed:meshHeading
pubmed:year
1977
pubmed:articleTitle
Modulation of pituitary thyrotropin releasing hormone receptor levels by estrogens and thyroid hormones.
pubmed:publicationType
Journal Article