Linked Life Data

15639149

Source:http://linkedlifedata.com/resource/pubmed/id/15639149

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2005-1-10
pubmed:abstractText
Pituitary melanotropes release alpha-melanocyte-stimulating hormone (alpha-MSH) and acetylated beta-endorphin (NAc beta-end) during stress responses. However, effects of stressors on plasma concentrations of these hormones are highly inconsistent among fish species. Here, we show that also within a species, the common carp (Cyprinus carpio), fish sometimes respond with elevated alpha-MSH and NAc beta-end plasma levels, and at other times not. The origin of this variable response was investigated by (1) studying the effects of corticotropin-releasing hormone (CRH) on alpha-MSH and NAc beta-end release in vitro, (2) establishing where in the second messenger pathway coupled to CRH receptors melanotrope responsiveness is determined, and (3) testing modulatory actions of other hypothalamic factors (here opioid beta-endorphin). Melanotropes were in a high or low responsive state to CRH in vitro, which was especially evident when tissue was tested from fish kept at higher ambient water temperatures, and this correlates with the variability in alpha-MSH and NAc beta-end responses in vivo. Relative rates of alpha-MSH and NAc beta-end release following stimulation with CRH in vitro match plasma level changes in vivo, and this indicates that the CRH pathway does act in vivo. cAMP did not stimulate melanotropes in the low responsive state to release hormones in vitro. Thus, the mechanism that determines the cell status, occurs downstream of cAMP accumulation. Opioid beta-endorphin differentially modulated the actions of CRH, as NAc beta-end, but not alpha-MSH, release was inhibited. This response was not observed in the stress paradigms studied. We conclude that the variation in alpha-MSH and NAc beta-end stress responses in vivo correlates with many CRH responses in vitro; whether a cell is in a high or low responsive state to CRH is determined downstream of accumulation of the second messenger. We propose that melanotropes have to be in the high responsive state to be activated by CRH during stress in carp and other teleosts.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0016-6480
pubmed:author
pubmed:issnType
Print
pubmed:volume
140
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
210-21
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Plasma alpha-MSH and acetylated beta-endorphin levels following stress vary according to CRH sensitivity of the pituitary melanotropes in common carp, Cyprinus carpio.
pubmed:affiliation
Department of Animal Physiology, Faculty of Science, University of Nijmegen, Toernooiveld 1, 6525 ED, Nijmegen, The Netherlands.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't