Linked Life Data

9614369

Source:http://linkedlifedata.com/resource/pubmed/id/9614369

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1998-6-11
pubmed:abstractText
Active immunization of ewes against inhibin (IMM) consistently increases ovulation rate but this response is not always accompanied by the expected rise in plasma FSH. Inhibin-related molecules also have local auto/paracrine effects within the ovary and the ovulatory response to IMM could be due to neutralization of one of these effects, independent of changing FSH levels. To investigate this, ovaries were collected from long-term IMM (n = 6) and control (CON; n = 8) ewes killed 48 h after progestagen withdrawal (late follicular phase) and all follicles > or = 3 mm were recovered to determine intrafollicular levels of inhibin A, activin A and follistatin by specific two-site immunoassay and oestradiol and testosterone by radioimmunoassay. Blood samples were collected to assess plasma FSH, oestradiol and inhibin antibody titres. Although plasma FSH levels were similar in IMM and CON ewes, IMM ewes had approximately 3-fold more follicles > or = 3 mm (P < 0.0001) and approximately 3-fold more oestrogenic follicle (P < 0.001) than CON ewes. Compared with CON ewes, follicles from IMM ewes had much higher concentrations of activin A (approximately 6-fold; P < 0.001) and inhibin A (approximately 3-fold; P < 0.001) but only slightly more follistatin (approximately 1.4-fold; not significant). The activin A:follistatin ratio in follicles from IMM ewes (approximately 1:1) was significantly higher (P < 0.001) than in follicles from CON ewes (approximately 0.3:1). Levels of inhibin antibody measured in follicular fluid (FF) from IMM ewes were similar to plasma levels. Given that activin A has been shown previously to up-regulate FSH receptors and aromatase activity in rat granulosa cells, the increase in intrafollicular activin A, unaccompanied by a rise in the concentration of its binding protein (follistatin), could explain how long-term IMM enhances follicle development and ovulation rate without necessarily promoting a sustained increase in FSH secretion.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0022-0795
pubmed:author
pubmed:issnType
Print
pubmed:volume
157
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
157-68
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Effects of active immunization of sheep against an amino terminal peptide of the inhibin alpha C subunit on intrafollicular levels of activin A, inhibin A and follistatin.
pubmed:affiliation
School of Animal and Microbial Sciences, University of Reading, UK.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't