Linked Life Data

15797953

Source:http://linkedlifedata.com/resource/pubmed/id/15797953

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2005-5-26
pubmed:abstractText
Orexins A and B are hypothalamic peptides that originate from the proteolytic cleavage of preproorexin and act through two subtypes of receptors, named OX1-R and OX2-R. OX1-R almost exclusively binds orexin-A, whereas OX2-R is nonselective for both orexins. We previously found that orexin-A, via the OX1-R, stimulates cortisol secretion from dispersed human adrenocortical cells. In this study, we demonstrate that six of eight cortisol-secreting adenomas expressed preproorexin mRNA, and seven of 10 adenomas contained measurable amounts of orexin-A but not orexin-B. Normal adrenal cortexes neither expressed preproorexin nor contained orexins. All adenomas expressed OX1-R and OX2-R mRNAs, and real-time PCR showed that the expression of both receptors was up-regulated in adenomas, compared with normal adrenal cortex. Orexin-A concentration-dependently raised basal cortisol secretion from freshly dispersed normal and adenomatous cells, minimal and maximal effective concentrations being 10(-10) and 10(-8) m, and the peptide efficacy (percent increase elicited by 10(-8) m orexin-A) was significantly higher in adenomas than in the normal adrenal cortex. Orexin-B was ineffective, thereby indicating that orexin secretagogue action is mediated by the OX1-R. In contrast, both orexins (10(-8) m) raised the proliferative activity of cultured normal and adenomatous cells, suggesting that this effect is mediated by OX2-R or both receptor subtypes. Collectively, our findings allow us to conclude that the orexin system is overexpressed in cortisol-secreting adenomas and suggest that orexin-A may act as an autocrine-paracrine regulator of the secretory activity and growth of some of these adrenal tumors.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0021-972X
pubmed:author
pubmed:issnType
Print
pubmed:volume
90
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3544-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Preproorexin and orexin receptors are expressed in cortisol-secreting adrenocortical adenomas, and orexins stimulate in vitro cortisol secretion and growth of tumor cells.
pubmed:affiliation
Department of Human Anatomy and Physiology, Section of Anatomy, University of Padova, Via Gabelli 65, I-35121 Padova, Italy.
pubmed:publicationType
Journal Article