Linked Life Data

16461548

Source:http://linkedlifedata.com/resource/pubmed/id/16461548

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2006-2-7
pubmed:abstractText
The aim was to determine whether follicle growth in cattle is accompanied by changes in levels of inhibin-A (inh-A), activin-A (act-A) and different Mr isoforms of follistatin (FS) in bovine follicular fluid (bFF), reflecting differential roles of these proteins during folliculogenesis. Follicles (n = 146) from 2-20 mm diameter were dissected from ovaries of approximately 40 cattle. Immunoassays were used to measure total FS, act-A, inh-A, oestradiol (E) and progesterone (P) levels; immunoblotting was used to quantify the relative abundance of different FS isoforms. Follicle growth from 2-6 mm was associated with a 6-fold increase in inh-A and 30-fold increase in act-A; FS remained uniformly high from 2-10 mm. From 6-2 mm, inh-A remained high while act-A and FS fell 3-fold and 2-fold, respectively. Act-A/FS ratio increased 20-fold from 2-6 mm before falling slightly through to 20 mm. Act-A/inh-A ratio increased 6-fold from 2-6 mm before falling 2-fold from 6 to 17-20 mm. These findings imply a marked increase in relative activin 'tone' around the stage at which dominant follicle selection occurs. When larger follicles (13-20 mm) were subdivided according to E/P ratio, those with high ( > 5) E/P ratio had lower (2-fold; P < 0.001) levels of inh-A and act-A in comparison to follicles with low ( < 5) E/P ratio, but there were no significant differences in FS, act-A/inh-A ratio or act-A/FS ratio. Thus follicle size, but not oestrogenic status, has a major influence on the intrafollicular balance between act-A and its opposing factors, inh-A and FS. Six FS isoforms were detected in bFF (apparent Mr: 65, 41, 37, 35, 33 and 31 kDa) averaging 6, 13, 24, 26, 13 and 17% respectively of total FS. During growth from 2-20 mm the proportion of total FS represented by 65, 41 and 37 kDa isoforms increased approximately 2-fold while the proportion represented by the 33 and 31 kDa isoforms decreased by 3-fold and 1.6-fold, respectively. Treatment of bovine granulosa cells in vitro with FSH and IGF alone or in combination increased total FS secretion up to 12-fold but did not affect the relative abundance of the five different FS isoforms detected. While the functional significance of the intriguing shift in FS isoform abundance in bFF during follicle development remains to be established, we have shown that a marked increase in intrafollicular activin 'tone' accompanies bovine follicle growth from 3-6 mm, corresponding to the stage at which the FSH-dependent follicle selection mechanism operates in this species.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0022-0795
pubmed:author
pubmed:issnType
Print
pubmed:volume
188
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
215-25
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Bovine follicle development is associated with divergent changes in activin-A, inhibin-A and follistatin and the relative abundance of different follistatin isoforms in follicular fluid.
pubmed:affiliation
School of Biological Sciences, The University of Reading, Whiteknights, Reading RG6 6AJ, UK.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't