Cavanagh A C, Rolfe B E, Athanasas-Platsis S, Quinn K A, Morton H
Department of Surgery, University of Queensland, Royal Brisbane Hospital, Australia.
J Reprod Fertil. 1991 Nov;93(2):355-65. doi: 10.1530/jrf.0.0930355.
The effects of synthetic platelet-activating factor (PAF-acether) and mouse embryo-conditioned medium (a source of embryo-derived PAF (EPAF)) on production of early pregnancy factor (EPF) were compared. Embryo-conditioned medium, itself inactive in the EPF bioassay, stimulated ovarian production of EPF in vitro but PAF-acether did not. In vivo, embryo-conditioned medium induced EPF activity in serum of oestrous female, but not in male, mice in contrast to PAF-acether, which induced activity in serum of both male and female mice. This PAF-induced activity was transitory, declining significantly by 2 h and disappearing by 3 h after injection. Activity induced by embryo-conditioned medium was first evident at 2 h after injection, serum concentrations increasing up to 6 h after injection. By discriminating between the behaviour of PAF-acether and EPAF, these studies reinforce the conclusions of other workers that the molecule produced by the embryo is not PAF. Further investigations into the mechanism of action of PAF-acether revealed that it is a potent inducer of activity in the EPF bioassay, with an absolute requirement for platelets in the spleen cell suspension used in the assay. This platelet-derived active species was bound specifically by an anti-EPF monoclonal antibody, indicating that it is EPF-like. This is consistent with parallel studies showing that platelets are not required for induction of activity by either pregnancy serum or purified EPF. These studies were applied to the PAF-induced leukotriene-like species, which had been found by others to be active in the EPF bioassay. Pregnancy serum induced the appearance of this substance from the spleen cell suspension used in the assay; thus the leukotriene-like substance may be regarded as an effector molecule in vitro or mediator of the initiating stimulus of EPF in the bioassay.
比较了合成血小板激活因子（PAF-乙醚）和小鼠胚胎条件培养基（胚胎源性PAF（EPAF）的来源）对早期妊娠因子（EPF）产生的影响。胚胎条件培养基本身在EPF生物测定中无活性，但能刺激卵巢在体外产生EPF，而PAF-乙醚则不能。在体内，胚胎条件培养基可诱导发情期雌性小鼠血清中出现EPF活性，但雄性小鼠血清中无此活性，与之形成对比的是，PAF-乙醚可诱导雄性和雌性小鼠血清中出现活性。这种PAF诱导的活性是短暂的，注射后2小时显著下降，3小时后消失。胚胎条件培养基诱导的活性在注射后2小时首次显现，血清浓度在注射后6小时内持续升高。通过区分PAF-乙醚和EPAF的行为，这些研究强化了其他研究人员的结论，即胚胎产生的分子不是PAF。对PAF-乙醚作用机制的进一步研究表明，它是EPF生物测定中活性的强力诱导剂，在该测定中使用的脾细胞悬液中绝对需要血小板。这种血小板衍生的活性物质能与抗EPF单克隆抗体特异性结合，表明它类似EPF。这与平行研究结果一致，即妊娠血清或纯化的EPF诱导活性时不需要血小板。这些研究应用于PAF诱导的白三烯样物质，其他人发现该物质在EPF生物测定中具有活性。妊娠血清可诱导该物质从测定中使用的脾细胞悬液中出现；因此，白三烯样物质可被视为体外效应分子或生物测定中EPF起始刺激的介质。
