The role of PAF in the establishment of pregnancy

激素是调节身体正常功能的基本化学信使。生殖尤其受到激素的广泛影响。非常早期胚胎的发育及其植入子宫的过程尚不清楚。一种新的激素参与了这一过程。这种激素，称为血小板活化因子（或PAF）是特殊的激素，因为它属于一类化学物质称为磷脂。这是非常罕见的。这种激素可以以一种明显矛盾的方式起作用。它由胚胎产生，使其能够作用于胚胎，刺激胚胎生长和存活。胚胎（某些物种）然后释放其他激素，阻止PAF作用于子宫。如果子宫对PAF的反应没有受到抑制，那么PAF就会作用于子宫，阻止妊娠的进一步发展（黄体溶解）。激素通过称为受体的特殊细胞蛋白作用于细胞。胚胎和子宫中PAF的受体似乎不同，因此可能导致这两种组织触发不同的细胞反应。我们有突变的老鼠，可以停止这两类受体的功能。将研究具有这些突变的小鼠的妊娠进展和胚胎发育，作为定义PAF在妊娠中如何起作用的手段。将对胚胎进行详细研究，以确定PAF通过其受体作用在胚胎内诱导的变化的性质。其中一种受体是一种全新的分子，以前人们不知道它能够作为细胞信号装置。这项研究将描述这种潜在的新受体是否以及如何在胚胎中起作用，以便将来详细研究其在正常细胞功能中的作用。它将展示这种单一的激素如何调节子宫和胚胎在怀孕过程中的相互矛盾的作用。

Hormones are essential chemical messengers that regulate the normal functions of the body. Reproduction in particular is widely influenced by hormones. The development of the very early embryo and its implantation into the uterus is not well understood. A new class of hormone has been implicated in this process. This hormone, known as platelet-activating factor (or PAF) is special among hormones since it belongs to a class of chemicals known as phospholipids. This is quite uncommon. This hormone can act in an apparently contradictory fashion. Its production by the embryo allows it to act back on the embryo to stimulate embryo growth and survival. The embryo (of some species) then releases other hormones which prevents the PAF from acting on the uterus. If this repression of the uterine response to PAF does not occur then PAF acts on the uterus to stop further progression of the pregnancy (luteolysis). Hormones act on cells via special cell proteins known as receptors. It seems that the receptor for PAF in the embryo and the uterus are different and may therefore result in triggering different cellular responses by these 2 tissues. We have available to us mice with mutations that stop the functioning of these two likely classes of receptors. The progress of pregnancy and the development of embryos in mice with these mutations will be studied as a means of defining how PAF acts in pregnancy. The embryo will be studied in detail to determine the nature of the changes induced within the embryo by PAF acting via its receptor. One of these receptors is an entirely new class of molecules not previously understood to be able to act as a cell signalling devise. This study will describe if and how this potential new receptor acts in the embryo, allowing future detailed investigation of its role in normal cell function. It will show how this single hormone can regulate both the uterus and embryo to have contradictory roles in the establishment of pregnancy.