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RESEARCH ARTICLE

Effects of corticotropin-releasing hormone and its antagonist on the gene expression of gonadotrophin-releasing hormone (GnRH) and GnRH receptor in the hypothalamus and anterior pituitary gland of follicular phase ewes

Magdalena Ciechanowska A B D , Magdalena Łapot A , Tadeusz Malewski C , Krystyna Mateusiak A , Tomasz Misztal A and Franciszek Przekop A
+ Author Affiliations
- Author Affiliations

A The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-110 Jabłonna, Warsaw, Poland.

B The General Karol Kaczkowski Military Institute of Hygiene and Epidemiology, Department of Pharmacology and Toxicology, Kozielska 4, 01-163 Warsaw, Poland.

C Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 3, 00-679 Warsaw, Poland.

D Corresponding author. Email: mciechanowska@wihe.waw.pl

Reproduction, Fertility and Development 23(6) 780-787 https://doi.org/10.1071/RD10341
Submitted: 17 December 2010  Accepted: 21 February 2011   Published: 7 July 2011

Abstract

There is no information in the literature regarding the effect of corticotropin-releasing hormone (CRH) on genes encoding gonadotrophin-releasing hormone (GnRH) and the GnRH receptor (GnRHR) in the hypothalamus or on GnRHR gene expression in the pituitary gland in vivo. Thus, the aim of the present study was to investigate, in follicular phase ewes, the effects of prolonged, intermittent infusion of small doses of CRH or its antagonist (α-helical CRH 9-41; CRH-A) into the third cerebral ventricle on GnRH mRNA and GnRHR mRNA levels in the hypothalamo–pituitary unit and on LH secretion. Stimulation or inhibition of CRH receptors significantly decreased or increased GnRH gene expression in the hypothalamus, respectively, and led to different responses in GnRHR gene expression in discrete hypothalamic areas. For example, CRH increased GnRHR gene expression in the preoptic area, but decreased it in the hypothalamus/stalk median eminence and in the anterior pituitary gland. In addition, CRH decreased LH secretion. Blockade of CRH receptors had the opposite effect on GnRHR gene expression. The results suggest that activation of CRH receptors in the hypothalamus of follicular phase ewes can modulate the biosynthesis and release of GnRH through complex changes in the expression of GnRH and GnRHR genes in the hypothalamo–anterior pituitary unit.

Additional keyword: LH.


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