Linked Life Data

8977432

Source:http://linkedlifedata.com/resource/pubmed/id/8977432

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1997-1-23
pubmed:abstractText
Continuous sampling of hypophyseal portal blood from unrestrained sheep is providing an unprecedented means for measuring and defining the characteristics of the secretory profile of GnRH. With this method, GnRH has been shown to be released in discrete pulses lasting 5-8 min, with the amplitude of some pulses exceeding 50-fold. Although the relationship between these pulses and the accompanying pulses of LH measured in the jugular vein are unambiguous, the relationship of GnRH pulses to the release of FSH has not been well defined due to the longer clearance of FSH. In previous studies we have shown that hypophyseal portal blood, in addition to serving as a source material for hypothalamic secretions, provides a means to define secretory patterns of pituitary hormones. Because of this we hypothesized that the GnRH-FSH secretory relationship would be easier to define in hypophyseal portal than in jugular vein blood before the secretory products are subjected to dispersion and clearance in circulation. To test this possibility, we monitored hormonal patterns in blood collected at 5-min intervals for 6-12 h from the peripheral and hypophyseal portal circulation of six ovariectomized ewes from a previous study. In contrast to the nonpulsatile pattern of FSH in the peripheral blood, 93% of the GnRH pulses were associated with essentially coincident, discrete pulses of FSH in the portal plasma. Of potentially even greater interest, additional episodes of FSH release were clearly discernible between the GnRH-associated pulses of FSH. As concentrations of peripheral plasma FSH did not reach those in hypophyseal portal plasma, the inter-GnRH episodes of FSH secretion could not result from contaminating peripheral blood. In addition to the episodic mode of secretion, substantial amounts of FSH were found between FSH pulses. This basal component of FSH appeared to be the dominant mode of secretion rather than pulses. The results of this study not only confirm that GnRH pulses lead to pulsatile release of FSH, they also suggest that some other mechanism or factor may be controlling the non-GnRH-associated episodes as well as the basal components of FSH secretion.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0013-7227
pubmed:author
pubmed:issnType
Print
pubmed:volume
138
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
424-32
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Neuroendocrine control of follicle-stimulating hormone (FSH) secretion. I. Direct evidence for separate episodic and basal components of FSH secretion.
pubmed:affiliation
Reproductive Sciences Program, University of Michigan, Ann Arbor 48109-0404, USA. vasantha@umich.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.