High impact information on GHRHR

• Interestingly, administration of the activator of adenylate cyclase, forskolin, decreased GHRH-R mRNA levels but had no effect on GHS-R, thus suggesting a distinct contribution of the various intracellular signals operating in somatotropes to the regulation of the expression of these receptors [1].
• Accordingly, an atypical activator of adenylate cyclase in the pig somatotrope is low-dose (10(-13) m) somatostatin, which also suppressed GHRH-R mRNA levels without altering GHS-R expression [1].
• Secretion of GH by pituitary somatotropes is primarily stimulated by the hypothalamic GHRH through the activation of a specific G protein-coupled receptor, GHRH receptor (GHRH-R) [1].
• By using a pig-rodent somatic cell hybrid panel, GHRHR was mapped to pig chromosome 18 (SSC18) with 100% concordance, and the regional assignment was SSC18q24 with 89% concordance [2].
• Primers were designed from the pig GHRHR sequence to amplify a 1.65-kb intronic fragment between exons 6 and 7 [2].

Biological context of GHRHR

• One novel receptor cDNA fragment was used to screen a porcine pituitary cDNA library and a full-length cDNA encoding a putative porcine GHRH receptor of 451 amino acids was isolated [3].
• Our mapping of pig GHRHR increases the comparative information available on the SSC18 maps and further confirms the synteny conservation between HSA7 and SSC18 [2].
• The GHRHR and IGFBP3 were found to map near to each other on human chromosome 7 (HSA7), and the pig IGFBP3 gene has been mapped to SSC18 by others [2].

Associations of GHRHR with chemical compounds

• Finally, dexamethasone did not modify GHRH-R or GHS-R expression [1].

Regulatory relationships of GHRHR

• Age-related declines in in vitro GH secretion were observed regardless of if the cells were stimulated by GHRH or by secretagogues that bypass the GHRH receptor (P < 0.001) [4].

Other interactions of GHRHR

• Age-related decreases in secretory function may be mediated by concurrent mechanisms relating to the expression of the GHRH receptor and of GH [4].

References