Influence of age on the control of thyrotropin secretion by thyrotropin-releasing hormone in the male rat

Neuroendocrinology
A DondaT Lemarchand-Béraud

Abstract

Alterations with age in the control of thyrotropin (TSH) secretion by thyrotropin-releasing hormone (TRH) were evaluated at the hypothalamic and pituitary levels in young (3-5 months) and old (22-24 months) male rats. In the hypothalamus, TRH was quantified in the median eminence and in the mediobasal hypothalamus; in the adenohypophysis the membrane receptors for TRH were evaluated as well as the accumulation of TRH in the gland. As for TSH, its concentration was determined in the anterior pituitary gland and in plasma. In the hypothalamus, the concentration of TRH did not differ between young and old rats in the whole mediobasal hypothalamus, but it was significantly less in the old rats at the level of the median eminence (29.9 +/- 2.8 vs. 52.2 +/- 4.3 ng/mg protein). In the adenohypophysis, the density of receptors for TRH was greater in the old than in the young rats (23.2 +/- 3.2 vs. 13.7 +/- 1.1 fmol MeTRH/mg gland)--with no change in the affinity constant--, and the amount of TRH detected was larger (10.8 +/- 1.8 vs. 2.8 +/- 0.6 pg/mg gland), illustrative of an age-related increase in TRH accumulation in the pituitary gland. The latter results are contrasting with the findings of unchanged pituitary and plasma concentra...Continue Reading

Citations

Apr 22, 2005·Reviews in Endocrine & Metabolic Disorders·Mouhammed Habra, Nicholas J Sarlis
Jun 4, 2008·Folia Histochemica Et Cytobiologica·Monika A PapiezAgata Gebarowska
May 6, 2014·Toxicology and Applied Pharmacology·Branka Šošić-JurjevićJosef Köhrle
Jan 1, 1995·Experimental Animals·M TakaokaN Goto
Dec 22, 2004·Arquivos brasileiros de endocrinologia e metabologia·Egberto G de Moura, Carmen C Pazos de Moura
Aug 24, 2019·Thyroid : Official Journal of the American Thyroid Association·Helena RakovDagmar Führer
Jan 14, 2020·Experimental and Clinical Endocrinology & Diabetes : Official Journal, German Society of Endocrinology [and] German Diabetes Association·Helena KerpDagmar Führer
Dec 20, 2020·Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology·Xiao-Tong KongLai-Xiang Xu

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