PMID: 2501768Jan 1, 1989Paper

Thyroid hormone modulation of TRH precursor levels in rat hypothalamus, pituitary, thyroid and blood

Peptides
M SimardJ M Hershman

Abstract

In the present study we have examined the in vivo effects of thyroid hormones and TRH on tissue and blood levels of TRH and TRH-Gly (pGlu-His-Pro-Gly), a TRH precursor. Using specific radioimmunoassays (RIAs), we measured TRH immunoreactivity (TRH-IR) and TRH-Gly-IR concentrations in blood, hypothalamus, anterior and posterior pituitary, and thyroid in euthyroid, hypothyroid and thyroxine (T4)-treated 250 g male Sprague-Dawley rats. TRH-Gly-IR and TRH-IR were detected in all of these tissues. Highly significant positive correlations between whole blood TRH-Gly-IR levels and the corresponding serum TSH values (p less than 0.01), whole blood TRH-IR versus serum TSH (p less than 0.01) and whole blood TRH-Gly-IR versus whole blood TRH-IR (p less than 0.01) are consistent with cosecretion of TRH and TRH precursor peptides into the circulation. Euthyroid rats injected with TRH IP (1 microgram/100 g b.wt.) and hypothyroid rats had 4-fold higher whole blood TRH-Gly-IR levels compared to euthyroid controls (p less than 0.0005). Injection of TRH into euthyroid rats significantly increased the TRH-Gly-IR concentration in the hypothalamus, anterior and posterior pituitary and thyroid. The increase in blood TRH-Gly-IR following intravenous ...Continue Reading

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Citations

Jan 1, 1991·Life Sciences·M MoriS Kobayashi
Jan 1, 1994·Peptides·H Houben, C Denef
Mar 18, 1999·Pharmacology, Biochemistry, and Behavior·A SattinR L Lloyd
Jun 1, 1990·International Journal of Andrology·A E PekaryS Friedman
May 27, 2008·Regulatory Peptides·David A KeireJoseph R Reeve

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