Platelet-Activating Factor: A Paracrine Factor in Preimplantation Stages of Reproduction?1

Platelet-activating factor (PAF) exerts its actions through activation of specific membrane binding sites found in a variety of tissues, including hypothalamus and endometrium. PAF has been identified in several reproductive tissues (i.e. embryo, ovary, uterus, and spermatozoon). In the uterus, PAF levels are hormonally controlled, being elevated by progesterone and prostaglandin E2 (PGE2). Antagonists of PAF interfere with sperm function, ovulation, and implantation. The available evidence suggests that PAF may be an important physiological regulator in reproduction.