Linked Life Data

3896760

Source:http://linkedlifedata.com/resource/pubmed/id/3896760

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1985-10-21
pubmed:abstractText
A transient increase in serum progesterone concentrations (to 1 ng/ml for 1-2 days) is observed in the majority of ewes before the first estrous cycle of the breeding season. To determine whether such a brief antecedent rise in progesterone ensures initiation of a full-length cycle by the next LH surge, synthetic GnRH was administered for 3 days to 24 anestrous ewes in a pulsatile fashion designed to mimic the pattern of LH secretion during the preovulatory period of the breeding season. Six ewes received no further treatment, and 6 ewes were treated sc with Silastic implants containing progesterone for 3 days before injecting GnRH. The remaining 12 ewes were treated with additional injections of GnRH every 4 h for the next 5 days. Four of these ewes received a second increase in GnRH pulse frequency, every 2 h and hourly on the subsequent 2 days. An LH surge was stimulated by each regimen of increasing GnRH pulse frequency in all ewes; progesterone pretreatment had no effect on its time of onset, duration, or amplitude. The LH surges induced full-length luteal phases in 10 of 10 ewes when preceded by either an exogenous (n = 6) or an endogenous (n = 4) progesterone increment, but in only 8 of 18 ewes not pretreated with progesterone. These results indicate that a transient increase in progesterone ensures that an ensuing LH surge will initiate an estrous cycle and suggest that progesterone may play an important role in the endocrine mechanisms governing transitions from acyclic to cyclic states.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0013-7227
pubmed:author
pubmed:issnType
Print
pubmed:volume
117
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1530-6
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1985
pubmed:articleTitle
Importance of short luteal phases in the endocrine mechanism controlling initiation of estrous cycles in anestrous ewes.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't