scholarly journals Comparative analysis of the pituitary and ovarian GnRH systems in the leopard gecko: signaling crosstalk between multiple receptor subtypes in ovarian follicles

2007 ◽  
Vol 38 (2) ◽  
pp. 289-304 ◽  
Author(s):  
Tadahiro Ikemoto ◽  
Min Kyun Park
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Expression Patterns ◽  
Ovarian Follicles ◽  
Anterior Pituitary Gland ◽  
Receptor Expression ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Leopard Gecko ◽  
Multiple Receptor

GnRH regulates reproductive functions through interaction with its pituitary receptor in vertebrates. The present study demonstrated that the leopard gecko possessed two and three genes for GnRH ligands and receptors, respectively, though one of the three receptor subtypes had long been thought not to exist in reptiles. Each receptor subtype showed a distinct pharmacology. All types of ligands and receptors showed different expression patterns, and were widely expressed both inside and outside the brain. This report also shows a comparison of the pituitary and ovarian GnRH systems in the leopard gecko during and after the egg-laying season. All three receptor subtypes were expressed in both the whole pituitary and ovary; however, only one receptor subtype could be detected in the anterior pituitary gland. In situ hybridization showed spatial expression patterns of ovarian receptors, and suggested co-expression of multiple receptor subtypes in granulosa cells of larger follicles. Co-transfection of receptor subtypes showed a distinct pharmacology in COS-7 cells compared with those of single transfections. These results suggest that distinct signaling mechanisms are involved in the pituitary and ovarian GnRH systems. Seasonal and developmental variations in receptor expression in the anterior pituitary gland and ovarian follicles may contribute to the seasonal breeding of this animal.

scholarly journals Differential Expression of Melatonin Receptor Subtypes MelIa, MelIb and MelIc in Relation to Melatonin Binding in the Male Songbird Brain

2014 ◽  
Vol 85 (1) ◽  
pp. 4-14 ◽  
Author(s):  
Leonida Fusani ◽  
Manfred Gahr
Keyword(s):  
Expression Patterns ◽  
General Pattern ◽  
Passerine Bird ◽  
Brain Regions ◽  
Receptor Expression ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Melatonin Receptor ◽  
Brain Areas ◽  
Specific Expression

Previous autoradiography studies illustrated that several areas of the avian brain can bind the pineal hormone melatonin. In birds, there are three melatonin receptor (MelR) subtypes: MelIa, MelIb and MelIc. To date, their brain distribution has not been studied in any passerine bird. Therefore, we investigated mRNA distribution of MelR subtypes in adjacent sections of the brain of two songbirds, the blackcap and the zebra finch, in parallel with that of 2-[125I]-iodomelatonin (IMEL) binding sites in the same brains. The general pattern of receptor expression shown by in situ hybridization of species-specific probes matched well with that of IMEL binding. However, the expression of the three subtypes was area specific with similar patterns in the two species. Some brain areas expressed only one receptor subtype, most brain regions co-expressed either MelIa with MelIb or MelIa with MelIc, whereas few areas expressed MelIb and MelIc or all three receptor subtypes. Since many sensory areas, most thalamic areas and subareas of the neopallium, a cortex analogue, express MelR, it is likely that most sensory motor integration functions are melatonin sensitive. Further, the area-specific expression patterns suggest that the regulatory role of melatonin differs among different brain areas. Since subareas of well-defined neural circuits, such as the visual system or the song control system, are equipped with different receptor types, we hypothesize a diversity of functions for melatonin in the control of sensory integration and behavior.

scholarly journals Ghrelin Receptor Expression and Colocalization with Anterior Pituitary Hormones Using a GHSR-GFP Mouse Line

Endocrinology ◽  
2012 ◽  
Vol 153 (11) ◽  
pp. 5452-5466 ◽  
Author(s):  
Alex Reichenbach ◽  
Frederik J. Steyn ◽  
Mark W. Sleeman ◽  
Zane B. Andrews
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Anterior Pituitary Gland ◽  
Receptor Expression ◽  
Egfp Expression ◽  
Pituitary Cells ◽  
Anterior Pituitary Hormones ◽  
Anterior Pituitary Cells ◽  
Males And Females

Abstract Ghrelin is the endogenous ligand for the GH secretagogue receptor (GHSR) and robustly stimulates GH release from the anterior pituitary gland. Ghrelin also regulates the secretion of anterior pituitary hormones including TSH, LH, prolactin (PRL), and ACTH. However, the relative contribution of a direct action at the GHSR in the anterior pituitary gland vs. an indirect action at the GHSR in the hypothalamus remains undefined. We used a novel GHSR-enhanced green fluorescent protein (eGFP) reporter mouse to quantify GHSR coexpression with GH, TSH, LH, PRL, and ACTH anterior pituitary cells in males vs. females and in chow-fed or calorie-restricted (CR) mice. GHSR-eGFP-expressing cells were only observed in anterior pituitary. The number of GHSR-eGFP-expressing cells was higher in male compared with females, and CR did not affect the GHSR-eGFP cell number. Double staining revealed 77% of somatotrophs expressed GHSR-eGFP in both males and females. Nineteen percent and 12.6% of corticotrophs, 21% and 9% of lactotrophs, 18% and 19% of gonadotrophs, and 3% and 9% of males and females, respectively, expressed GHSR-eGFP. CR increased the number of TSH cells, but suppressed the number of lactotrophs and gonadotrophs, expressing GHSR-eGFP compared with controls. These studies support a robust stimulatory action of ghrelin via the GHSR on GH secretion and identify a previously unknown sexual dimorphism in the GHSR expression in the anterior pituitary. CR affects GHSR-eGFP expression on lactotrophs, gonadotrophs, and thyrotrophs, which may mediate reproductive function and energy metabolism during periods of negative energy balance. The low to moderate expression of GHSR-eGFP suggests that ghrelin plays a minor direct role on remaining anterior pituitary cells.

scholarly journals Liver receptor homologue-1 regulates gonadotrope function

2007 ◽  
Vol 38 (2) ◽  
pp. 207-219 ◽  
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.

Effects of estrogens on the characteristics of [3H]spiroperidol and [3H]RU24213 binding in rat anterior pituitary gland and brain

1979 ◽  
Vol 16 (2) ◽  
pp. 99-112 ◽  
Author(s):  
Thérèse Di Paolo ◽  
Réjean Carmichael ◽  
Fernand Labrie ◽  
Jean-Pierre Raynaud
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Anterior Pituitary Gland
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