Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
1998-8-13
pubmed:abstractText
Interleukin (IL)-6, a multifunctional cytokine originally described as a T cell-derived factor, is also produced by different cell types, and it influences a wide variety of physiological and pathophysiological processes. Recent studies further suggest that IL-6 has a role in down-regulating hormone production by endocrine organs and can negatively affect the steroidogenic capacity of both ovaries and testes. Thus, the aims of this investigation were to examine whether IL-6 plays a role in luteolysis and, more specifically, to determine whether luteal cells express the IL-6 gene, whether this expression is developmentally and hormonally regulated in pregnancy, and whether the corpus luteum could be a target for IL-6 action. Using semiquantitative RT-PCR, messenger RNA (mRNA) encoding both components of the IL-6 receptor [the ligand-binding subunit (IL-6 R) and the IL-6 R-associated signal transducer (gp130)] were found to be highly expressed in corpora lutea throughout pregnancy. In contrast, IL-6 mRNA expression was barely detectable from day 4 through the end of pregnancy, whereas a sharp and abrupt expression of IL-6 mRNA occurred immediately after parturition. Although the corpus luteum does not express IL-6 mRNA during most of pregnancy, it could be induced to express this gene with an in vivo injection of the bacterial endotoxin, lipopolysaccharide. In addition, when corpora lutea from day-15 pregnant rats were isolated and maintained in culture, IL-6 mRNA that was undetectable at 0 h increased in a time-related manner and reached significant levels after 4 h of incubation, followed by a similar increase in IL-6 protein secreted in the culture media. Isolation of the small and large luteal cells by elutriation indicated that both cell populations can secrete IL-6 in culture. The apparent ability of luteal cells to spontaneously express IL-6 in vitro, together with the lack of IL-6 expression during most of pregnancy, led us to examine whether the IL-6 gene is silenced throughout pregnancy by luteotropic hormones. Corpora lutea from day-15 pregnant rats were cultured in the presence of different doses of progesterone; the synthetic glucocorticoid, dexamethasone; 17beta-estradiol; and PRL. Progesterone and dexamethasone markedly inhibited IL-6 mRNA expression, whereas 17beta-estradiol had a minimal inhibitory effect, and PRL did not affect IL-6 mRNA expression. In summary, results of this investigation have revealed that the rat corpus luteum expresses the IL-6 receptor system and that luteal cells are able to secrete IL-6. However, IL-6 gene expression is silenced during most of pregnancy, probably by the high levels of progesterone locally produced in the corpus luteum. The salient finding that progesterone and glucocorticoid strongly inhibit the expression of IL-6 in the corpus luteum suggests that one important luteotropic role of progesterone and glucocorticoids could be to prevent the expression of IL-6, which might have a deleterious effect on luteal function.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0013-7227
pubmed:author
pubmed:issnType
Print
pubmed:volume
139
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3597-605
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:9681513-Animals, pubmed-meshheading:9681513-Cells, Cultured, pubmed-meshheading:9681513-Corpus Luteum, pubmed-meshheading:9681513-Dexamethasone, pubmed-meshheading:9681513-Estradiol, pubmed-meshheading:9681513-Female, pubmed-meshheading:9681513-Gene Expression Regulation, pubmed-meshheading:9681513-Glucocorticoids, pubmed-meshheading:9681513-Interleukin-6, pubmed-meshheading:9681513-Kinetics, pubmed-meshheading:9681513-Lipopolysaccharides, pubmed-meshheading:9681513-Pregnancy, pubmed-meshheading:9681513-Progesterone, pubmed-meshheading:9681513-RNA, Messenger, pubmed-meshheading:9681513-Rats, pubmed-meshheading:9681513-Rats, Sprague-Dawley, pubmed-meshheading:9681513-Receptors, Interleukin-6, pubmed-meshheading:9681513-Signal Transduction, pubmed-meshheading:9681513-Time Factors
pubmed:year
1998
pubmed:articleTitle
The expression of interleukin-6 in the pregnant rat corpus luteum and its regulation by progesterone and glucocorticoid.
pubmed:affiliation
Department of Physiology and Biophysics, College of Medicine, University of Illinois, Chicago 60612-7342, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.