Differential regulation of GHRH-receptor and GHS-receptor expression by long-term in vitro treatment of ovine pituitary cells with GHRP-2 and GHRH

Roh, Sang-Gun, Doconto, Maria, Feng, Dan Dan and Chen, Chen (2006) Differential regulation of GHRH-receptor and GHS-receptor expression by long-term in vitro treatment of ovine pituitary cells with GHRP-2 and GHRH. Endocrine, 30 1: 55-62. doi:10.1385/ENDO:30:1:55


Author Roh, Sang-Gun
Doconto, Maria
Feng, Dan Dan
Chen, Chen
Title Differential regulation of GHRH-receptor and GHS-receptor expression by long-term in vitro treatment of ovine pituitary cells with GHRP-2 and GHRH
Journal name Endocrine   Check publisher's open access policy
ISSN 0969-711X
1559-0100
1355-008X
Publication date 2006-08-01
Year available 2006
Sub-type Article (original research)
DOI 10.1385/ENDO:30:1:55
Volume 30
Issue 1
Start page 55
End page 62
Total pages 8
Place of publication Totowa, N. J.
Publisher Humana
Collection year 2006
Language eng
Subject 110306 Endocrinology
110201 Cardiology (incl. Cardiovascular Diseases)
111201 Cancer Cell Biology
Abstract Abstract GH secretion is regulated by GHRH and somatostatin via actions on their specific receptors in pituitary somatotropes. Ghrelin and synthetic analogs, GHRPs, also stimulate GH release via GHS-receptors (GHS-R). To examine the long-term effect of GHRH and/or GHRP on somatotropes, primary cultured ovine somatotropes were treated with GHRH (10−9 and 10−8 M) and GHRP-2 (10−8 and 10−7 M) for up to 2 d. After treatment, culture medium was collected for GH assay, and total RNA was extracted for RT-PCR analysis. To evaluate cell cultures used in this report, somatotrope-enriched pituitary cells were challenged by 6 h GHRH and dexamethasone (DEX) treatment. As expected, GHRH significantly decreased, whereas DEX increased, the levels of GHRH-R mRNA. Combined low doses of GHRH (10−9 M) and GHRP-2 (10−8 M) treatment for 24 h increased accumulated GH secretion, significantly more than that induced by high doses of GHRH (10−8 M) and GHRP-2 (10−7 M). While levels of GHRH-R mRNA increased, GHS-R mRNA levels were decreased by low doses of GHRH and GHRP-2 for 24 h. High doses of GHRH and/or GHRP-2 for 2 d did not increase GH secretion in the second day of treatment and reduced the level of GHRH-R mRNA. High doses of GHRP-2 treatment decreased the levels of both GHRH-R and GHS-R mRNA. Low doses of GHRH and/or GHRP-2 for 2 d increased the level of GHS-R mRNA without changing GHRH-R mRNA levels. Such treatment also increased ghrelin- (10−9 M) or ghrelin/GHRH (10−9 M)-induced GH secretion. These results suggest that low doses of GHRP-2 and GHRH prime somatotropes for stimulation by GHRH and ghrelin.
Keyword GHRP-2
GHRH
GH
GHRH receptor
GHS receptor
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