Linked Life Data

7835284

Source:http://linkedlifedata.com/resource/pubmed/id/7835284

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1995-3-2
pubmed:abstractText
The circadian variation in immunoreactive (I-) ACTH and corticosterone was studied at several stages throughout rat pregnancy and compared with those before pregnancy and during lactation. Serial blood samples were obtained from chronically cannulated, conscious rats at 2- to 3-h intervals beginning at 0800 h at diestrus of the cycle; on days 2, 6, 10, 14, 18, and 22 of pregnancy (term = day 23); and on day 4 of lactation. Plasma I-ACTH and corticosterone were determined in all samples, and indices of their circadian variation (acrophase, mesor, and amplitude) were derived by cosinor analyses within each rat. A circadian variation in corticosterone was clearly evident in all groups, with individual cosinor r2 values being consistently high. Plasma I-ACTH also exhibited distinct circadian variation up to day 14 of pregnancy, but the cosinor r2 value then fell (P < 0.05, by analysis of variance) and remained low during lactation. Mesor levels (midpoint of the derived circadian range) of I-ACTH fell (P < 0.05) by 34% to 20.6 +/- 2.4 pg/ml by day 2 of pregnancy; corticosterone also fell (P < 0.05) by 34% to 141 +/- 27 ng/ml, and both changes were due primarily to reductions in peak levels. I-ACTH mesors then remained effectively unchanged for the remainder of pregnancy, but mesor corticosterone increased progressively after day 10 to reach a maximum of 286 +/- 28 ng/ml by day 22, and this rise was due to elevations in both trough and peak corticosterone levels. Further changes occurred after parturition, with mesor I-ACTH increasing more than 2-fold between day 22 of pregnancy and day 4 of lactation, whereas mesor corticosterone declined by more than half over the same period. Plasma corticosterone and I-ACTH were positively associated within rats in all groups (P < 0.01), but the common slope of this association increased considerably after midgestation, indicative of higher corticosterone levels for a given concentration of I-ACTH. In summary, this study identifies marked changes in the hypothalamic-pituitary-adrenal axis during rat pregnancy and lactation. Although a circadian variation in corticosterone was observed throughout, that in plasma I-ACTH was evident early in pregnancy but declined after midgestation. Absolute concentrations of plasma I-ACTH and corticosterone fell in parallel early in pregnancy, but corticosterone subsequently increased without any change in I-ACTH.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0013-7227
pubmed:author
pubmed:issnType
Print
pubmed:volume
136
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
512-20
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
The hypothalamic-pituitary-adrenal axis in rat pregnancy and lactation: circadian variation and interrelationship of plasma adrenocorticotropin and corticosterone.
pubmed:affiliation
Department of Anatomy and Human Biology, University of Western Australia, Nedlands, Perth.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't