Lipopolysaccharide induces nitric oxide synthase expression and platelet-activating factor increases nitric oxide production in human fetal membranes in culture.
BACKGROUND
Platelet-activating factor and nitric oxide may be involved in the initiation of human labour as inflammatory mediators. The aim of this study was to test whether platelet-activating factor and lipopolysaccharide were able to induce nitric oxide synthase expression and stimulate the production of nitric oxide in human fetal membrane explants in culture.


METHODS
Fetal membranes were collected from Caesarean sections at term. RNA was extracted from membranes and subjected to a qualitative RT-PCR to assess the baseline expression of iNOS. Discs of fetal membranes were cultured for 24 hours in the presence of platelet-activating factor at a dose range of 0.1 nanomolar--1 micomolar or 1 microgram/ml lipopolysaccharide. Nitric oxide production was measured via nitrite ions in the culture medium and mRNA for iNOS was detected by RT-PCR.


RESULTS
Culturing the membrane discs in medium containing serum induced nitric oxide synthase expression and platelet-activating factor significantly stimulated the production of nitric oxide under these conditions. When cultured without serum inducible nitric oxide synthase expression was induced by lipopolysaccharide, but not by platelet-activating factor.


CONCLUSIONS
Platelet-activating factor may have a role in the initiation of labour, at term or preterm, via the increased local production of nitric oxide as an inflammatory mediator. In this model of intrauterine infection, lipopolysaccharide was found to induce iNOS expression by fetal membranes, and this mechanism could be involved in preterm labour.
Seyffarth
Gunter
G
Perinatal and Maternal Studies Group, University of Wolverhampton, UK.
Nelson
Paul N
PN
Dunmore
Simon J
SJ
Rodrigo
Nalinda
N
Murphy
Damian J
DJ
Carson
Ray J
RJ
D046508:Culture Techniques; D004790:Enzyme Induction / Q000187:drug effects; D005321:Extraembryonic Membranes / Q000737:chemistry / Q000187:drug effects* / Q000201:enzymology*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000276:immunology; D052247:Nitric Oxide Synthase Type II; D010972:Platelet Activating Factor / Q000494:pharmacology*
D008070:Lipopolysaccharides; D010972:Platelet Activating Factor; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II