Lipid mediator production by post-implantation rat embryos in vitro

The production of inflammatory lipid mediators by post-implantation rodent embryos was examined in this study. Explanted day 10 rat embryos, either intact or after homogenization, were cultured for 3 hr in vitro and the resulting culture medium and embryonic tissue were assessed for eicosanoids and platelet-activating factor (PAF). The rank order of cyclooxygenase arachidonate products produced by intact embryos was as follows: 6-keto-PGF1 alpha much greater than congruent to PGF2 alpha congruent to TXB2. No lipoxygenase products of arachidonic acid metabolism were detected by either high performance liquid chromatography or radioimmunoassay. PAF production was detectable in embryonic cultures. Homogenization of rat embryos prior to in vitro culture enhanced eicosanoid and PAF production from 2.1-6.9 fold over intact embryos. These findings demonstrate the extent of lipid metabolism by early post-implantation rat embryos and support the concept that potent lipid mediators of inflammation generated by the conceptus may play a role in both the initiation and maintenance of pregnancy.