The Central Effect of β-Endorphin and Naloxone on the Expression of GnRH Gene and GnRH Receptor (GnRH-R) Gene in the Hypothalamus, and on GnRH-R Gene in the Anterior Pituitary Gland in Follicular Phase Ewes

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.

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Implication of Dopaminergic Systems on GnRH and GnRHR Genes Expression in the Hypothalamus and GnRH-R Gene Expression in the Anterior Pituitary Gland of Anestrous Ewes

Experimental and Clinical Endocrinology & Diabetes ◽

10.1055/s-2008-1042406 ◽

2008 ◽

Vol 116 (06) ◽

pp. 357-362 ◽

Cited By ~ 6

Author(s):

M. Ciechanowska ◽

M. Łapot ◽

T. Malewski ◽

K. Mateusiak ◽

T. Misztal ◽

...

Keyword(s):

Gene Expression ◽

Pituitary Gland ◽

Anterior Pituitary ◽

Anterior Pituitary Gland ◽

R Gene ◽

Dopaminergic Systems ◽

Genes Expression

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Liver receptor homologue-1 regulates gonadotrope function

Journal of Molecular Endocrinology ◽

10.1677/jme-06-0001 ◽

2007 ◽

Vol 38 (2) ◽

pp. 207-219 ◽

Cited By ~ 12

Author(s):

Weiming Zheng ◽

Jingying Yang ◽

Qiaorong Jiang ◽

Zhibin He ◽

Lisa M Halvorson

Keyword(s):

Pituitary Gland ◽

Anterior Pituitary ◽

Nuclear Hormone Receptor ◽

Gnrh Receptor ◽

Anterior Pituitary Gland ◽

Receptor Expression ◽

Pituitary Cells ◽

Steroidogenic Factor 1 ◽

Regulate Gene Expression ◽

Mrna And Protein Expression

Over the past decade, substantial advances have been made in our understanding of the transcription factors which regulate gene expression in gonadotropes. One of the most important of these factors, steroidogenic factor-1 (SF-1; NR5A1) is critical for gonadotropin and GnRH-receptor expression. Interestingly, a closely related nuclear hormone receptor, liver receptor homologue-1 (LRH-1; NR5A2) has recently been detected in the anterior pituitary gland; however, its functional significance in this tissue has not been investigated. For the experiments reported here, we hypothesized that LRH-1 plays a previously unrecognized role in gonadotrope physiology. Towards this end, we first demonstrate LRH-1 mRNA and protein expression in both primary pituitary cells and gonadotrope-derived cell lines. We next show that LRH-1 stimulates promoter activity of the GnRH-receptor and gonadotropin subunit genes. Within the LHβ gene, this response appears to be mediated by DNA-binding and transactivation through previously characterized SF-1 cis-elements. To our knowledge, this is the first report demonstrating a functional role for LRH-1 in the gonadotrope population of the anterior pituitary gland.

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