Expression of 5-lipoxygenase and 5-lipoxygenase-activating protein in human fetal membranes throughout pregnancy and at term

Lipoxygenase metabolites may be involved in human parturition. 5-lipoxygena se (5-LOX) catalyses the first steps in the synthesis of leukotrienes from arachidonic acid, and its activity is dependent on 5-LOX activating protein (FLAP). The expression of 5-LOX and FLAP were investigated in fetal membra nes to determine whether there are changes with gestational age or at term with the onset of labour. No significant differences were found in the expr ession of 5-LOX or FLAP mRNA in the amnion at different gestational ages or at term. in the chorion-decidua, 5-LOX mRNA expression was significantly h igher in the first trimester of pregnancy than in the second and third trim esters. At term, there was a significant increase in both 5-LOX mRNA and pr otein expression in the chorion-decidua in the time after labour, compared with the time before labour. The expression of FLAP mRNA was also significa ntly higher in the chorion-decidua in the first trimester of pregnancy comp ared with the third trimester, and at term in the time after labour compare d with the time before labour. Expression of FLAP protein was not studied, as an antibody is not currently available. These results are consistent wit h a role for 5-LOX and FLAP in the control of parturition at term, and also suggest an involvement earlier in pregnancy.