Linked Life Data

12193535

Source:http://linkedlifedata.com/resource/pubmed/id/12193535

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
9
pubmed:dateCreated
2002-8-23
pubmed:abstractText
We examined the time course of action of GnRH pulse frequency on gonadotropin subunit gene transcription and assessed the roles of GnRH, follistatin (FS), and activin on differential transcription of the LHbeta and FSHbeta genes. GnRH-deficient male rats were pulsed with 25 ng GnRH either every 30 min (fast frequency) or every 240 min (slow frequency) for 1-24 h. Both GnRH frequencies increased alpha primary transcript (PT) 5-fold within 6 h, but only fast frequency GnRH increased alpha mRNA. Only fast frequency GnRH pulses affected LHbeta PT, resulting in 6- to 9-fold increases between 1-24 h. Fast frequency GnRH pulses transiently increased FSHbeta PT at 1 and 6 h (4- and 2-fold, respectively); but by 24 h FSHbeta PT had returned to control levels and was correlated to a 5- to 9-fold increase in FS mRNA. In contrast, slow GnRH pulses increased FSHbeta PT 3- and 6-fold at 8 and 24 h, respectively, which was correlated with a decline in FS mRNA. Activin mRNA did not change significantly after either GnRH frequency, but tended to fall after fast pulses. To test whether activin was required for the effects of GnRH on FSHbeta transcription, rats were treated with GnRH pulses every 240 min for 8 h +/- FS. FS treatment alone markedly decreased basal FSHbeta PT. GnRH in the presence of FS increased FSHbeta PT 8-fold but did not restore FSHbeta transcription to control or GnRH alone values. In summary, whereas alpha-subunit transcription is independent of frequency, an increase in alpha mRNA requires fast frequency GnRH pulses. Fast frequency GnRH pulses increased both LHbeta and FSHbeta transcription, but the response of FSHbeta was transient. The sustained rise in FSHbeta transcription and mRNA expression required slow frequency GnRH pulses and was correlated to low FS mRNA. Neutralization of pituitary activin by exogenous FS markedly reduced basal FSHbeta PT and mRNA but did not prevent the stimulation of FSHbeta transcription by slow frequency GnRH pulses. These studies suggest that the frequency regulation of FSHbeta transcription involves both direct actions of GnRH and indirect effects, via changes in pituitary FS expression.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0013-7227
pubmed:author
pubmed:issnType
Print
pubmed:volume
143
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3243-9
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
GnRH pulse frequency modulation of gonadotropin subunit gene transcription in normal gonadotropes-assessment by primary transcript assay provides evidence for roles of GnRH and follistatin.
pubmed:affiliation
Division of Endocrinology, Department of Internal Medicine, and the Center for Research in Reproduction, University of Virginia, Charlottesville, Virginia 22908, USA. llb3k@virginia.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.