Linked Life Data

18162520

Source:http://linkedlifedata.com/resource/pubmed/id/18162520

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2008-3-24
pubmed:abstractText
There is strong evidence that kisspeptin acts to regulate GnRH secretion, but whether there is also a component of action on the gonadotropes is not clear. Using quantitative RT-PCR, we found that G protein-coupled receptor-54 mRNA is expressed in ovine pituitary cell fractions enriched for gonadotropes as well as in somatotropes and lactotropes. To test whether kisspeptin acts directly on the pituitary gonadotropes, we first examined LH release from primary ovine pituitary cell cultures treated with kisspeptin. We found that kisspeptin treatment increased the concentration of LH in culture media by 80%, compared with control, but only in pituitary cultures from ewes during the follicular phase of the estrous cycle. After this, we determined whether kisspeptin acts on the pituitary gland in vivo. Using GnRH-replaced ovariectomized hypothalamo-pituitary-disconnected ewes, we were not able to achieve any effect of kisspeptin on LH under steady-state conditions or during the period of an estrogen-induced LH surge. Finally, we collected hypophysial portal blood samples from ovariectomized ewes and measured kisspeptin levels. Low but detectable amounts of kisspeptin were found in portal plasma, but levels were similar in ovariectomized ewes that were untreated or given estrogen to elicit an LH surge. Thus, although we observed an effect of kisspeptin on LH release in vitro in some situations, similar findings were not obtained in vivo. Moreover, the low concentrations of kisspeptin in hypophysial portal blood and the lack of any change during the period of an estrogen-induced GnRH/LH surge suggest that action on the pituitary gland is not of major consequence in terms of LH release.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0013-7227
pubmed:author
pubmed:issnType
Print
pubmed:volume
149
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1951-9
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Kisspeptin is present in ovine hypophysial portal blood but does not increase during the preovulatory luteinizing hormone surge: evidence that gonadotropes are not direct targets of kisspeptin in vivo.
pubmed:affiliation
Department of Physiology, Monash University, Victoria 3880, Australia.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't